JP2857198B2 - Rubber composition for heat-resistant and vibration-proof rubber material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rubber composition for a heat-resistant and vibration-proof rubber material, and more particularly, to an ethylene-propylene-diene copolymer rubber (hereinafter sometimes referred to as “EPDM”). ) And carbon black, and a rubber composition for a heat-resistant and vibration-proof rubber material which can provide a vulcanized rubber having excellent dynamic fatigue resistance and heat resistance.

Technical background of the invention The anti-vibration rubber is characterized by having both a so-called support function necessary for mounting the supported body on the foundation and a so-called anti-vibration function for preventing transmission of vibration and impact. However, in order to obtain a sufficient support function, mechanical strength characteristics are an important factor in the design of a vibration-proof rubber.

Therefore, in most cases, the vibration-proof rubber is generally used to suppress vibration of a heavy object, and as a prerequisite, a mechanical strength characteristic for supporting the heavy object is required first, rather than a vibration damping characteristic. Therefore, as the matrix of the currently used anti-vibration rubber material, most are natural rubber (NR) having excellent mechanical strength characteristics or a blend thereof. For example, engine mounts for automobiles require not only the mechanical strength characteristics that support the engine, but also the comfort of riding, so natural rubber (NR) with excellent mechanical strength characteristics and styrene with a large vibration damping effect Matrices blended with butadiene rubber (SBR) are also widely used.

However, with the recent improvement in the performance of automobiles, there is a demand for improved heat resistance of vibration-proof rubber materials, and the natural rubber (NR) -based materials used above cannot meet the demand. It is the present situation.

Therefore, ethylene-propylene-diene copolymer rubber (EPDM), which is excellent in heat resistance, weather resistance, and ozone resistance, has attracted attention, and research on vibration-proof rubber materials using EPDM has recently been active.

However, conventional EPDM is practically superior to natural rubber (NR) materials in terms of heat resistance, but its mechanical strength characteristics, such as dynamic fatigue resistance, are much lower than those of NR materials. EPDM-based anti-vibration rubber which can be used has not existed conventionally.

As described above, the reason that conventional EPDM is inferior in mechanical strength properties to NR-based materials is that EPDM is inferior in dispersibility and affinity of carbon black as compared to diene-based rubbers such as NR. Is mentioned. This suggests that carbon black dispersed in a blend of EPDM and a highly unsaturated rubber always contains a large amount of highly unsaturated rubber [J.
E.Callan, WMHess, GEScott "Rubber Chemical Technology (Rubber
Chem.Technol.) ", 44 , 814 (1971)].

By the way, a vulcanized rubber made of EPDM, unlike a vulcanized rubber made of an NR-based material having stretched crystallinity, shows excellent mechanical strength properties only when EPDM is mixed with carbon black. In other words, depending on the characteristics of carbon black,
The strength of the mechanical properties of vulcanized rubber using EPDM is determined.

Further, when EPDM is used for dynamic applications such as engine mounts of automobiles, it is necessary to increase the molecular weight of EPDM, so that the dispersibility of carbon black tends to be further deteriorated. Therefore, the emergence of rubber compositions for heat-resistant anti-vibration rubber materials using carbon black that can be well dispersed in high molecular weight EPDM suitable for dynamic applications and that can improve mechanical strength characteristics More wanted. Furthermore, EPDM has poor crack growth resistance as compared with NR-based materials, so it not only has good dispersibility and imparts excellent mechanical strength properties to EPDM, but also has excellent crack growth resistance. The appearance of a rubber composition for a heat-resistant and vibration-proof rubber material using carbon black capable of imparting properties has been desired.

Japanese Patent Application Laid-Open No. Sho 62-104850 discloses a rubber composition having both high reinforcement and low heat build-up, a nitrogen adsorption specific surface area (N ₂ SA) of 35 to 75 m ² / g, and a DBP oil absorption of 100.
The carbon black in the characteristic region of ml / 100g or more, and the half-width (ΔDst) of the aggregate distribution by centrifugal sedimentation method and D
The value of the parameter (ΔDst · DBP) ^1/2 · (N ₂ SA) ^-1 consisting of BP oil absorption and nitrogen adsorption specific surface area (N ₂ SA) is 3.5
Carbon black having a ratio D peak / D ₅₀ of 0.95 or more, which is the ratio of the most frequent occurrence diameter (D peak) to the average aggregate diameter (D ₅₀ ) of the aggregation distribution by the centrifugal sedimentation method,
A rubber composition comprising 30 to 200 parts by weight per 100 parts by weight is disclosed.

Object of the Invention The present invention is intended to solve the problems associated with the prior art as described above, and provides a vulcanized rubber excellent in mechanical strength characteristics and heat resistance represented by dynamic fatigue resistance. It is an object of the present invention to provide a rubber composition for a heat-resistant vibration-proof rubber material, especially a vibration-proof rubber composition for an automobile such as an engine mount vibration-proof rubber composition.

SUMMARY OF THE INVENTION The rubber composition for a heat-resistant and vibration-proof rubber material according to the present invention comprises the following carbon black (B) 20 to 100 parts by weight of ethylene-propylene-diene copolymer rubber (A) shown below. It is characterized by containing 120 parts by weight.

Ethylene-propylene-diene copolymer rubber (A): ethylene content is 60 to 75 mol%, intrinsic viscosity [η] measured in decalin at 135 ° C is 3.3 to 5.0 dl / g,
When the iodine value is 10 to 35 and ω _γ (= ω ₂ / ω ₁ ), which is an index of workability and physical properties, determined by a dynamic viscoelasticity test,
High molecular weight ethylene-propylene-diene copolymer rubber in the range of 30 to 130.

Carbon black (B): The iodine adsorption amount (IA) is 35 to 50 mg / g, and the dibutyl phthalate oil absorption (DBPA) exceeds 120 ml / 100 g and 140 ml / 10
Within the range of less than 0g, ΔDBPA (= DBPA-24M4DBPA)
The most frequent value (Dst) of the Stokes relative diameter of the carbon black aggregate in the range of more than 40 ml / 100 g and less than 50 ml / 100 g and centrifugal sedimentation analysis is: Dst ≧ {(DBPA) ² − (IA) ² } ^1/2 +80 ... Soft carbon black satisfying the relationship of (I).

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the rubber composition for a heat-resistant and vibration-proof rubber material according to the present invention will be specifically described.

The rubber composition for a heat-resistant and vibration-proof rubber material according to the present invention comprises a specific ethylene-propylene-diene copolymer rubber (A) and a specific carbon black (B).

Ethylene-propylene-diene copolymer rubber (A) The ethylene-propylene-diene copolymer rubber (A) used in the present invention comprises ethylene, propylene and a non-conjugated diene.

As the non-conjugated diene, specifically, a chain non-conjugated diene such as 1,4-hexadiene, ethylidene norbornene (ENB), norbornadiene, methylene norbornene, dicyclopentadiene, 2-methylnorbornadiene, 5-vinyl- Cyclic non-conjugated dienes such as 2-norbornene; Among them, ENB is particularly preferably used.

In the present invention, EPDM having excellent heat resistance is used as a main component of the rubber composition for a heat and vibration proof rubber material.

The ethylene-propylene-diene copolymer rubber (A) used in the present invention has an intrinsic viscosity [η] of 3.5 to 5.0 dl / g, preferably 3.7 to 4.2 dl / g, measured at 135 ° C. in decalin. It is in. A high molecular weight EPDM having an intrinsic viscosity [η] within the above range can provide a rubber composition having excellent dynamic fatigue resistance.

Further, the ethylene-propylene-diene copolymer rubber (A) used in the present invention has an iodine value of 10 to 35, preferably 15 to 30. EPDM with an iodine value within the above range is used as an index when evaluating the self-holding property of rubber when a heavy object is placed, and the compression set (compression set is generally large in iodine value) And a rubber composition having an excellent balance between crack growth resistance (the crack growth resistance is generally better as the iodine value is smaller).

Further, the ethylene-propylene used in the present invention
The diene copolymer rubber (A) has an ethylene content of 60 to 75.
Mol%, preferably in the range of 65-72 mol%. EPDM having an ethylene content within the above range can provide a rubber composition having excellent low-temperature flexibility enough to withstand use in cold regions while maintaining the mechanical strength of the polymer.

In the present invention, EPDM as described above is desirable as the rubber matrix.

The present inventors have proposed a dynamic viscoelasticity test (strain rate 10%, temperature 190 ° C., sample table) to specify EPDM having excellent dynamic fatigue resistance.
Parallel plate, frequency; 1.58 × 10 ^-2 rad / S to 5 × 10 ² r
ad / S) in, the horizontal axis represents frequency and the vertical axis represents the complex modulus G ^*, G * ⁼ the corresponding frequency is omega ₂ to 1E6, also a frequency corresponding to G ^{* =} 1E5 as omega ₁ ω _r
= Ω ₂ / ω _1, and the index of ω _r is used to express the state of workability and physical properties of EPDM. This index ω _r
Is closely related to the side chain and entanglement of EPDM, the composition distribution, and the molecular weight distribution. By using this index, the state of processability and physical properties can be well expressed. Ethylene-propylene-diene copolymer rubber (A) according to the present invention
Among them, ethylene-propylene-diene copolymer rubber (EPDM) having ω _r in the range of 30 to 130 is particularly excellent in kneadability with carbon black and mechanical strength characteristics.

In the present invention, a so-called oil-extended type ethylene-propylene-diene copolymer rubber obtained by mixing a softener (extending oil) as described later in the above-described ethylene-propylene-diene copolymer rubber is used. It is preferable in operation for use.

In the present invention, the softener is used in an amount of 10 to 120 parts by weight, preferably 30 to 80 parts by weight, based on 100 parts by weight of the ethylene-propylene-diene copolymer rubber.

Carbon black (B) The carbon black (B) used in the present invention has an iodine adsorption amount (IA) of 35 to 50 mg / g, preferably 42 to 50 mg / g.
Within the range.

If the iodine adsorption amount (IA) of the carbon black is less than 35 mg / g, the mechanical strength characteristics such as tensile strength tend to decrease, which is not preferable. On the other hand, the iodine adsorption amount (I
If A) exceeds 50 mg / g, the dispersibility and extrusion characteristics of carbon black tend to decrease when a large amount of carbon black is added to the rubber component, which is not preferable.

The carbon black (B) used in the present invention
Has a dibutyl phthalate oil absorption (DBPA) in the range of more than 120 ml / 100 g and less than 140 ml / 100 g.

Dibutyl phthalate oil absorption of carbon black (DBP
A) of less than 120 ml / 100 g is not preferred because mechanical strength characteristics such as tensile strength tend to decrease. On the other hand, if the dibutyl phthalate oil absorption (DBPA) is 140 ml / 100 g or more, the rebound resilience and compression set characteristics tend to decrease, such being undesirable.

Further, the carbon black (B) used in the present invention
Means that △ DBPA (difference between the value of DBPA and the value of DBPA after 4 times compression processing, DBPA-24M4DBPA) is in the range of more than 40 ml / 100 g and less than 50 ml / 100 g, and the carbon black aggregate by centrifugal sedimentation analysis Most frequent value of the Stokes equivalent diameter (Dst)
Satisfies the following relationship: Dst ≧ ｛(DBPA) ² − (IA) ² ｝ ^1/2 +80 (I)

The above △ DBPA indicates the value of the structure that is easily broken when subjected to shearing force in the structure of carbon black, and the numerical value of △ DBPA exceeding 40 ml / 100 g and less than 50 ml / 100 g is the value of general carbon black. Higher than

If the most frequent value (Dst) of the Stokes equivalent diameter of the carbon black aggregate is smaller than the right side of the above formula (I), when a large amount of carbon black is blended with the rubber component, the dispersibility, rebound resilience, etc. Is unfavorable because the characteristics tend to decrease.

Iodine adsorption (IA), dibutyl phthalate oil absorption (D
BPA) and ΔDBPA are within the above ranges, and the carbon black having the most frequent value (Dst) of the Stokes equivalent diameter of the carbon black aggregate satisfying the relationship of the above formula (I) is a large amount. Even when blended,
A rubber composition exhibiting excellent dispersibility in a rubber composition and having excellent tensile properties such as tensile stress, rebound resilience, compression set properties, and extrusion properties can be provided.

The carbon black (B) used in the present invention has an iodine adsorption amount (IA) as compared with the soft furnace carbon black proposed in Japanese Patent Application No. 63-161349 (Japanese Patent Application Laid-Open No. Hei. On the big side,
ΔDBPA is within the above range and Dst satisfies the relationship of the above formula (I), so that even when compounded in a large amount, it shows excellent dispersibility, rebound resilience, compression It is presumed that a rubber composition having excellent strain characteristics is provided.

In the present invention, while satisfying each of the above-described characteristic values, the degree of dispersion of carbon black in the rubber composition measured by the ASTM D2663-87B method during rubber compounding is preferably 95% or more, and more preferably 97% or more. Carbon black is desirable. This means that the degree of dispersion is
This is because when 95% or more of the carbon black according to the present invention is blended with the rubber, properties such as crack growth resistance, rebound resilience, compression set, and tensile strength can be more effectively exhibited.

The physicochemical properties of the carbon black (B) used in the present invention are measured as follows.

(1) Iodine adsorption amount (IA) It is measured according to JIS K 6221 (1982) 6.1.1.

(2) DBP oil absorption A method [mechanical method] (DBPA) Measured according to JIS K 6221 (1982) 6.1.2.

(3) 24M4DBP oil absorption (24M4DBPA) Measured according to ASTM D 3493-86.

(4) Average particle size (dn) 0.2 mg of carbon black was added to 1 ml of chloroform.
Disperse with an ultrasonic cleaner for minutes. This dispersion sample was fixed on a carbon support membrane, and was directly magnified by an electron microscope at a magnification of 2000.
At a magnification of 0x and a final magnification of 60000x, the diameters of 2,000 or more carbon black particles were randomly measured from the obtained photo, and the measured values were averaged from a histogram created by dividing the measured values into 48 sections. (Dn) is calculated.

Here, di: the diameter of the histogram corresponding to the i-th ni: number (5) Method of analyzing carbon black aggregate (aggregate) size by sedimentation analysis Equipment used Disk centrifuge (photo sedimentometer) (DCF) (England) Joyce Loebl Manufacture method In a 30% aqueous methanol solution to which a certain amount of surfactant is added, add 0.02 to 0.06% by weight of carbon black,
Sonicate to completely disperse. After injecting 20 to 30 ml of a settling solution (spin solution) of a 25 V / V% glycerin aqueous solution into a disk rotating at 6000 rpm, 0.02 to 0.03 ml of the above dispersion is injected.

The recorder is operated simultaneously with the addition of the dispersion liquid, and the amount of carbon black aggregate passing through one point near the outer periphery of the rotating disk by settling is optically measured, and the amount is recorded as a histogram with respect to time.

The sedimentation time is converted into a Stokes equivalent diameter by the following equation (a general type of Stokes equation), and a histogram of the Stokes equivalent diameter of the carbon black aggregate and its frequency is obtained.

In the above equation, d is the Stokes equivalent diameter of the carbon black aggregate passing through the optical measurement point of the rotating disk at the time t at the start of sedimentation.

The constant K is the amount and viscosity of the spin solution at the time of measurement and the density difference from carbon black (the true density of carbon black is 1.
86 g / ml) and a constant determined by the rotating disk. For example, when 22.5 ml of a 25 V / V% glycerin aqueous solution is used as a spin solution and the disk rotation speed is 6000 rpm at a measurement temperature of 20 ° C., the K value is 752.0, and d is nm,
t is displayed in minutes.

Definition of Dst In the histogram of the Stokes equivalent diameter of the aggregate obtained by the above measurement operation, the Stokes equivalent diameter that gives the most frequent (actually, the maximum absorbance because an optical measurement is performed) is Dst (Mode) Called,
It is a measure of the average size of the carbon black aggregate.

△ in the histogram of the Stokes equivalent diameter defined above D _50, Ds
Two Stokes diameters having a frequency of 1/2 of t are D ₁ and D ₂
If (D ₂ > D ₁ ), ΔD ₅₀ is defined by (D ₂ −D ₁ ) [nm].

In the histogram of the Stokes equivalent diameter defined above S (aggregate size distribution index), the aggregate size distribution index S is calculated by the following formula from the values of Dst and D _2.

S = 0.84932 × log (D ₂ / Dst) This S is a measure of the distribution width of a relatively large aggregate size.

In the present invention, the carbon black (B) is used in an amount of 20 to 120 parts by weight, preferably 30 to 70 parts by weight, based on 100 parts by weight of the ethylene-propylene-diene copolymer rubber (A). By using the carbon black (B) in an amount within the above range, a rubber composition capable of providing a vulcanized rubber having excellent dynamic fatigue resistance can be obtained.

Production of vulcanized rubber In order to obtain a vulcanized rubber from the rubber composition for a heat-resistant and vibration-proof rubber material according to the present invention, as in the case of vulcanizing a general rubber, an unvulcanized compounded rubber is obtained by a method described later. (Rubber composition for heat-resistant and vibration-proof rubber material) is prepared once, and then the compounded rubber is molded into an intended shape and then vulcanized.

When producing a vulcanized rubber from the rubber composition for a heat and vibration proof rubber material according to the present invention, depending on the intended use of the vulcanized rubber and the performance based thereon, in addition to the above components (A) and (B), The type and amount of the softening agent, the type and amount of the vulcanizing agent, vulcanization accelerator, vulcanization aid and other compounds constituting the vulcanization system, and the process for producing the vulcanized rubber are appropriately selected. Is done.

As the softener, a softener used for rubber is usually used.Specifically, process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt,
Petroleum softeners such as petrolatum; coal tar softeners such as coal tar and coal tar pitch; fatty oil softeners such as castor oil, linseed oil, rapeseed oil, and coconut oil; tall oil;
Sub; waxes such as beeswax, carnauba wax, lanolin;
Ricinoleic acid, palmitic acid, barium stearate,
Fatty acids and fatty acid salts such as calcium stearate and zinc laurate; synthetic polymer substances such as petroleum resin, atactic polypropylene, and coumarone indene resin are used. Among them, petroleum softeners are preferably used,
Particularly, process oil is preferably used.

In the present invention, the softening agent is 10 to 1 to 100 parts by weight of the ethylene-propylene-diene copolymer rubber.
It is used in an amount of 20 parts by weight, preferably 30 to 80 parts by weight.

When a vulcanized rubber is produced from the rubber composition for a heat and vibration proof rubber material according to the present invention, the following sulfur compound is used as a vulcanizing agent. Specific examples of the sulfur compound include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide,
Tetramethylthiuram disulfide, selenium dimethyldithiocarbamate and the like are used, and among them, sulfur is preferably used.

The sulfur compound is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the ethylene-propylene-diene copolymer rubber (A).

When producing a vulcanized rubber from the rubber composition for a heat and vibration proof rubber material according to the present invention, it is preferable to use a vulcanizing agent and a vulcanization accelerator in combination. As the vulcanization accelerator, specifically, N
-Cyclohexyl-2-benzothiazole-sulfenamide, N-oxydiethylene-2-benzothiazole-sulfenamide, N, N-diisopropyl-2-benzothiazole-sulfenamide, 2-mercaptobenzothiazole, 2- ( 2,4-dinitrophenyl) mercaptobenzothiazole, 2- (2,6-diethyl-4-morpholinothio) benzothiazole, dibenzothiazyl-
Thiazole compounds such as disulfides; guanidine compounds such as diphenylguanidine, triphenylguanidine, diorthotolylguanidine, orthotolyl by guanide, diphenylanidin phthalate; acetaldehyde-aniline reactant, butyraldehyde-aniline condensate, hexa Aldehyde-amine or aldehyde-ammonia compounds such as methylenetetramine and acetaldehyde-ammonia reactants; imidazoline compounds such as 2-mercaptoimidazoline; thiocarbanilide;
Thiourea compounds such as diethylthiourea, dibutylthiourea, trimethylthiourea and diorthotolylthiourea; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide and the like Thiuram-based compounds; zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc di-n-butyldithiocarbamate, zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, selenium dimethyldithiocarbamate, tellurium diethyldithiocarbamate, and the like Dithionate compounds; xanthate compounds such as zinc dibutylxanthate; Other compounds, such as zinc oxide is used.

The vulcanization accelerator is 0.1 to 20 parts by weight based on 100 parts by weight of the ethylene-propylene-diene copolymer rubber (A),
Preferably it is used in an amount of 0.2 to 10 parts by weight.

The unvulcanized compounded rubber is prepared by the following method.
That is, using a mixer such as a Banbury mixer, the components (A) and (B) and the softener were heated to 80 to 170 ° C.
The mixture is kneaded at a temperature of 3 to 10 minutes, and then, using a roll such as an open roll, a vulcanizing agent and, if necessary, a vulcanization accelerator or a vulcanization aid are further mixed, and a roll temperature of 40 to 80 ° C. After kneading for 5 to 30 minutes, the kneaded product is extruded to prepare a ribbon-shaped or sheet-shaped compounded rubber.

The compounded rubber thus prepared is molded by a molding machine, for example, an injection molding machine, a transfer molding machine, a compression molding machine or the like. As a heating method, steam, electricity, or the like can be used.

EFFECT OF THE INVENTION The rubber composition for a heat-resistant and vibration-proof rubber material according to the present invention comprises a specific ethylene-propylene-diene copolymer rubber (A) and a specific carbon black (B) in a specific ratio. Therefore, there is an effect that a vulcanized rubber having excellent mechanical strength characteristics represented by dynamic fatigue resistance and excellent heat resistance can be provided.

Since the rubber composition for a heat-resistant and vibration-proof rubber material according to the present invention has the above-mentioned effects, it has been considered that the rubber composition cannot be used unless natural rubber or a blend thereof is used. It is suitable as an anti-vibration rubber material for automobiles such as hangers. Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In addition, the evaluation test method of the vulcanized sheet in Examples and Comparative Examples is as follows.

(1) Tensile test A vulcanized rubber sheet was punched out to obtain a No. 3 type dumbbell test piece described in JIS K 6301.
According to the method defined in K 6301 3 Section, measurement temperature 25 ° C., subjected to tensile test at a tensile rate of 500 mm / min condition was measured strength T _B and elongation E _B tension.

(2) Heat aging resistance The heat aging resistance is evaluated by the following changes in tensile strength retention, elongation retention, and JIS A hardness according to 6.5 of JIS K 6301-1975.

(I) A dumbbell No. 1 type tensile test piece of JIS K 6301 was punched out from the longitudinal direction of the sheet, the test piece was left at 120 ° C. for 72 hours, returned to room temperature, and subjected to a tensile test at a speed of 200 mm / min. Tensile strength (T Baged) and elongation (E Bage)
Measure d). On the other hand, the tensile strength (T Borig) and elongation (E Borig) of the sample before thermal aging are measured in advance, and the retention of tensile strength and the retention of elongation are calculated.

Tensile strength retention [%] = (T Baged / T Borig) x 100 Elongation retention [%] = (E Baged / E Borig) x 100 (ii) Changes in JIS A hardness (JIS K 6301) A here _{H = H 2 -H 1, a} H is the change in JIS a hardness, H ₁ hardness before vulcanization, H
₂ indicates hardness after vulcanization.

(3) Dynamic Fatigue Test (Monsanto Fatigue Test) A vulcanized rubber sheet was punched out to obtain a No. 3 type dumbbell test piece described in JIS K 6301. The strain was subjected to extension fatigue under the conditions of a measurement temperature of 40 ° C. and a rotation speed of 300 rpm, and the average value of the number of times of dumbbell cutting was used as an index of dynamic fatigue resistance.

(4) Crack growth test Crack growth due to bending was measured using a dematcher type tester (rotational speed: 300 rpm) according to ASTM D813.
The speed at which the vulcanized rubber test specimen was cut by 10 mm at 40 ° C. for each of the books was represented by an average value.

(5) Low-temperature impact embrittlement test The embrittlement temperature Tb was measured according to JIS K6301.

(6) Exothermic test According to ASTM D 623, an exothermic test was performed using a Goodrich flexometer under the conditions of a load of 15 lb and a stroke of 6.9 mm, and the rising temperature (change temperature) T ₂ − T ₁ = ΔT was measured. The number of test pieces used for the measurement was two, and the experiment starting temperature was 37 ° C.

(7) Compression set test was carried out according to JIS K 6301.

(8) Kneading exotherm test The exothermic temperature at the time of kneading EPDM and carbon black was read from a thermometer provided in the kneading machine.

Comparative Example 1 First, using an 8 inch roll, the surface temperature of the open roll was 50 ° C. for the front roll, 50 ° C. for the rear roll, and the rotation speed was 16 rpm for the front roll and 18 rpm for the rear roll. Intrinsic viscosity [η] 2.8 dl / g, iodine value 22.
0, ethylene content 68.0 mol%, of omega _gamma 110 ethylene - propylene - diene copolymer rubber (hereinafter abbreviated as EPDM-1)
Was masticated for 2 minutes.

Next, 1 part by weight of stearic acid and 5 parts by weight of Zinc Hua No. 1 were added to 100 parts by weight of masticated EPDM-1 and kneaded, and further, FEF-HS carbon black [manufactured by Nippon Steel Chemical Co., Ltd. Niteron # 10] and 60 parts by weight of process oil [P-300 manufactured by Fujikosan Co., Ltd.] were added and kneaded.

Then, sulfur [Hosoi Chemical Industry Co., Ltd.]
0.8% by weight and Noxeller P as a vulcanization accelerator
Z [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.] 1.5 parts by weight, trade name Noxeller TT [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.] 1.5 parts by weight and trade name Noxeller M [manufactured by Ouchi Shinko Chemical Industry Co., Ltd.] 0.
After adding and kneading 5 parts by weight, the mixture is dispensed into a sheet and 160 ° C.
For 20 minutes to obtain a vulcanized sheet having a thickness of 2 mm, and a physical property test was performed on the vulcanized sheet. However, for the test piece for crack growth resistance test, the press time was set to 22 minutes.

 Table 1 shows the results.

Comparative Example 2 In Comparative Example 1, the limiting viscosity [η] measured in decalin at 135 ° C. was 3.9 dl / g, and the iodine value was 24.
0, ethylene content 69.0 mol of ethylene omega _gamma 125 - propylene - diene copolymer rubber except for using (hereinafter, abbreviated as EPDM-2) is in the same manner as in Comparative Example 1, the thickness of 2mm the vulcanized sheet And a physical property test was conducted.

 Table 1 shows the results.

Comparative Example 3 In Comparative Example 1, the limiting viscosity [η] measured in decalin at 135 ° C. was 3.8 dl / g, and the iodine value was 40.
0, ethylene content 68.5 mol of ethylene omega _gamma 140 - propylene - diene copolymer rubber except for using (hereinafter, abbreviated as EPDM-3) is in the same manner as in Comparative Example 1, the thickness of 2mm the vulcanized sheet And a physical property test was conducted.

 Table 1 shows the results.

Comparative Example 4 In Comparative Example 1, the limiting viscosity [η] measured in decalin at 135 ° C. was 3.9 dl / g, and the iodine value was 23.
0, ethylene content 78.0 mol, omega _gamma 120 ethylene - propylene - diene copolymer rubber except for using (hereinafter, abbreviated as EPDM-4) is in the same manner as in Comparative Example 1, the thickness of 2mm the vulcanized sheet And a physical property test was conducted.

 Table 1 shows the results.

From Table 1, the following is understood.

In the vulcanized sheet of Comparative Example 1, the intrinsic viscosity [η] of EPDM-1 was smaller than the intrinsic viscosity [η] of EPDM-2 of Comparative Example 2. % Is poor in dynamic fatigue resistance.

In the vulcanized sheet of Comparative Example 3, since the iodine value of EPDM-3 was larger than the iodine value of EPDM-2 of Comparative Example 2, the crack growth resistance was poor compared to the vulcanized sheet of Comparative Example 2. Poor trauma resistance.

The vulcanized sheet of Comparative Example 4 is excellent in mechanical strength as compared with the vulcanized sheet of Comparative Example 2, but has a low low-temperature impact embrittlement temperature, and thus has poor low-temperature characteristics. It cannot be used for products that can be used.

The vulcanized rubber sheet of Comparative Example 2 using EPDM-2 has an excellent balance of mechanical strength, dynamic fatigue resistance and low-temperature properties, but can be replaced with the natural rubber or the blend thereof as the object of the present invention. Not as good as possible.

Examples 1 to 3 and Comparative Examples 5 to 9 [Production Examples 1 to 7 of Carbon Black] FIG. 1 is a longitudinal sectional front view of one example of a production apparatus suitable for producing carbon black according to the present invention, and FIG. Is AA
FIG. 3 is a cross-sectional view as viewed in the direction of the arrow, and FIG. 3 is a cross-sectional view as viewed in the direction of the arrow BB.

This manufacturing apparatus is disclosed in Japanese Patent Application Laid-Open No. Sho 60-223865 (applicant:
It has the same configuration as the device described in Asahi Carbon Co., Ltd.).

1 and 2, a venturi 3 is coaxially connected to the downstream side of the combustion gas filling chamber 2, and then a reaction chamber 4, a reaction continuation and rapid cooling chamber 5 and a flue 6 are formed. Are linked. The combustion gas filling chamber 2 has an insertion port provided through the center of the front end wall, and includes a water cooling jacket 7 for a feedstock introducing device (not shown) and fixing fittings 8, 8 '.
Is attached. In the first half of the combustion gas filling chamber 2, two oxygen-containing gas introduction ports 9,
9 'are provided, and two fuel fluid inlets 10, 10' are separately provided from the outer periphery of the side wall in these vertical spaces. These oxygen-containing gas inlets 9, 9 'are provided with fuel combustion devices 11, 11' at their central axis positions.

Cooling water press-in sprayers a to
g is installed, and the expansion and contraction of the reaction chamber area can be freely set by selecting these sprayers a to g.

As shown in FIG. 1 and FIG.
In the first half, inlets such as 12, 12 ', 12 "and 12 are arranged in parallel and tangentially so that the swirling direction of the oxygen-containing gas and / or the fuel fluid can be changed ( With respect to the turning direction of the inlets 9, 9 ', the inlet 12-1
2 ″ is forward direction, inlet 12-12 is reverse direction).

The amount of oxygen-containing gas and fuel fluid introduced from the 9, 9 'and 10, 10' inlets into the combustion gas filling chamber 2;
Of the oxygen-containing gas introduced from the inlets 13 to 13 and the swirling direction thereof, the operation positions of the cooling water injection sprayers a to g provided in the reaction continuation and rapid cooling chamber 5, and further, the introduction of the base oil. By appropriately selecting the pressure and the introduction position, soft furnace carbon blacks having different physicochemical property values were produced.

In addition, about the control of DBPA, the usual adjusting agent (alkali metal compound) was used suitably other than the turning direction of 12-12. The properties of the feedstock are as shown in Table 2, and
Fuel oil C was used as a fuel fluid. Table 3 shows the production conditions and physicochemical properties of carbon black.

The carbon blacks of Production Examples 1 to 3 are the carbon blacks used in the present invention, and the carbon blacks of Production Examples 1 to 3 are used in Examples 1 to 3, respectively.

The carbon black of Production Example 4 was Dst, the carbon black of Production Example 5 was DBPA, the carbon black of Production Example 6 was ΔDBPA, and the carbon black of Production Example 7 was IA. The carbon blacks of Production Examples 4 to 7 are used in Comparative Examples 5 to 8, respectively.

The carbon black listed as Comparative Example 9 in Table 3 is a typical soft high-structure carbon black, FEF grade carbon black “Asahi Carbon Co., Ltd.
Product name Asahi # 60H].

In Comparative Example 1, EPDM-2 was used instead of EPDM-1, and the carbon black shown in Table 3 was used instead of FEF-HS carbon. A vulcanized sheet was obtained and a physical property test was performed.

 Table 4 shows the results.

Control Example 70 parts by weight of natural rubber (NR) [RSS 1] and styrene
30 parts by weight of butadiene rubber (SBR) [trade name: Tuffden 1530, manufactured by Asahi Kasei Corporation], 1 part by weight of stearic acid,
Comparative Example 1 5 parts by weight of Zinc Hua No. 1, 50 parts by weight of FEF carbon black [Asahi Carbon Co., Ltd., 60H] and 40 parts by weight of process oil [P-300, manufactured by Fujikosan Co., Ltd.] Kneading was carried out in the same manner as described above.

To the kneaded material thus obtained, 1 part by weight of sulfur and a vulcanization accelerator [Noxeller, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.]
[CZ] was added and kneaded with a roll, then separated into sheets and pressed at 150 ° C. for 20 minutes to obtain a vulcanized sheet having a thickness of 2 mm, and subjected to a physical property test. However, for the test piece for crack growth resistance test, the press time was set to 22 minutes.

 Table 4 shows the results.

From Tables 3 and 4, the following (1) to (4) are understood.

(1) In the vulcanized rubber sheets of Examples 1 to 3, Comparative Examples 5 to
Despite using a carbon black having a larger particle diameter than the carbon black of No. 8, that is, a carbon black having a small iodine adsorption amount (IA), an important modulus M100 as a characteristic of the vibration damping rubber material is the same as that of Comparative Examples 5 to 8. Compared to vulcanized rubber sheets, they are large and have excellent mechanical strength.

(2) The carbon black of Example 3 has substantially the same particle size and structure as the carbon black of Comparative Example 1, but the dispersibility of the carbon black can be improved by controlling the aggregate of the carbon black. it can. The carbon black of Example 3 having excellent dispersibility lowers the heat generation temperature during kneading and gives a good kneading compound.

When the carbon black specified in the present invention is used, a vulcanized rubber sheet having a stress-elongation curve (SS curve) having a large modulus M100 and a small modulus M300 can be obtained. That is, a vulcanized rubber sheet having crack growth resistance equivalent to that of natural rubber and excellent in dynamic fatigue resistance can be obtained.

(4) When the carbon blacks of Examples 1 to 3 having excellent dispersibility are used, the heat generation temperature due to repeated fatigue is small,
Example 3 shows almost the same value as the control example using the blend of NR and SBR.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional front view of one example of a production apparatus suitable for producing carbon black according to the present invention, FIG. 2 is a cross-sectional view taken along the line AA, and FIG. The figure is a cross-sectional view taken along the line BB. 1 ... carbon black production equipment 2 ... combustion gas filling chamber 3 ... venturi section 4 ... reaction chamber 5 ... reaction continuation and rapid cooling chamber 6 ... flue 7 ... water cooling jacket 8, 8 '... fixed Metal fittings 9, 9 '... gas inlet 10, 10' ... fuel fluid inlet 11, 11 '... fuel combustion device 12, 12', 12 ", 12 ... inlet 13,13 ... inlet a ~ G ... cooling water press-in sprayer

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Mishima 3 Chigusa Beach, Ichihara City, Chiba Prefecture Inside Mitsui Oil Chemical Industry Co., Ltd. (72) Inventor Seisaku Kato 18-18 Shimokonocho, Niitsu City, Niigata Prefecture (72 ) Inventor Akira Yamaya 1-4-4, Matsuzono, Niigata City, Niigata Prefecture (72) Inventor Jiro Koyaku 330 Kinumagawa Rubber Industry Co., Ltd. 330, Naganumacho, Chiba City, Chiba Prefecture (72) Inventor Norihiro Harada Chiba Prefecture, Chiba 330, Nagasaki-cho, Kinugawa Rubber Industry Co., Ltd. (56) References JP-A-3-227375 (JP, A) JP-A-2-11664 (JP, A) JP-A-57-94030 (JP, A) CARBON BLACK Yearbook 1987, Carbon Black Association, July 1, 1987, no. 37, p. 63 CARBON BLACK Yearbook 1985, Carbon Black Association, July 1, 1985, No. 35, p. 52 CARBON BLACK Yearbook 1979, Carbon Black Association, July 1979, p. 50 (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 23/00-23/36 C08K 3/04 C09C 1/44-1/60

Claims (3)

(57) [Claims] The present invention is characterized in that 20 to 120 parts by weight of carbon black (B) shown below is contained with respect to 100 parts by weight of ethylene-propylene-diene copolymer rubber (A) shown below. Rubber composition for heat-resistant anti-vibration rubber material; Ethylene-propylene-diene copolymer rubber (A): Ethylene content is 60 to 75 mol%, intrinsic viscosity [η] measured in decalin at 135 ° C. is 3.3 to 5.0 dl / g, iodine value is 10 to 35, and ω _γ (= ω ₂ / ω ₁ ), which is an index of workability and physical properties, obtained by a dynamic viscoelasticity test is 30.
High molecular weight ethylene-propylene- in the range of ~ 130
Diene copolymer rubber carbon black (B): Iodine adsorption (IA) is 35-50 mg / g, dibutyl phthalate oil absorption (DBPA) exceeds 120 ml / 100 g and 140 ml / 100 g
ΔDBPA (= DBPA-24M4DBPA) is less than 40
The most frequent value (Dst) of the Stokes-equivalent diameter of the carbon black aggregate in the range of more than 50 ml / 100 g and less than 50 ml / 100 g, and Dst ≧ {(DBPA) ² − (IA) ² } ^1/2 +80 ... Soft carbon black satisfying the relationship of (I). 2. An oil-extended type ethylene-ethylene copolymer containing a softener, wherein the ethylene-propylene-diene copolymer rubber (A) is a rubber.
The rubber composition for a heat and vibration proof rubber material according to claim 1, wherein the rubber composition is a propylene-diene copolymer rubber. 3. The method according to claim 1, wherein the carbon black (B) is ASTM D2.
The heat-resistant and vibration-proof rubber according to claim 1 or 2, wherein the carbon black is a soft carbon black having a degree of dispersion of 95% or more in the rubber composition as measured by the 663-87B method. Rubber composition for materials.