JP3191593B2 - Ethylene-α-olefin-non-conjugated diene copolymer rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to ethylene which has a high foaming property at the time of foaming, is excellent in workability, shape retention, compression set, etc., and is suitable for a wide range of uses including sealing materials for automobiles, and particularly suitable for sponge rubber. -Α-olefin-non-conjugated diene copolymer rubber composition.

[0002]

2. Description of the Related Art Ethylene-.alpha.-olefin-non-conjugated diene copolymer rubber is excellent in various properties such as heat resistance, ozone resistance and weather resistance, and is sponge rubber, especially for automobile door seals, roof side rails and trunks. It is widely used as a sealing material such as a seal. However, as the performance of automobiles increases, the performance of sponge rubber composed of ethylene-α-olefin-non-conjugated diene copolymer rubber is required to have a high level. For example, noise such as engine noise generated at the time of high-speed driving of a car, wind noise around a door, and the like, such as leakage into a room and rain leakage, largely depend on the sealing performance of sponge rubber around a door. Sponge rubber requires extremely high sealing performance. In addition, when the door of a car is closed, the sponge rubber is left in a compressed state for a long time, so the “sludge” due to compression
It is considered important that the compression set (generally represented by the compression set as an index) is small. Therefore, the demands on the sealing performance and low "sagging" of sponge rubber are becoming increasingly severe. In recent years, since the cross-sectional shape of sponge rubber for automotive sealing materials has become more complicated, when sponge rubber is manufactured by the usual continuous cross-linking method, the sponge deforms due to its own weight before completion of cross-linking and foaming. As a result, there is a problem that the desired shape cannot be maintained. Therefore, a sponge rubber having excellent shape retention as an index of the shape collapse is required. Further, in order to respond to the demand for cost reduction of sponge rubber, sponge rubber is highly foamed, that is, while having a small foaming specific gravity, it has excellent overall characteristics including the sealing performance, low “set” property, shape retention property and the like. There is a new demand for sponge rubber. Furthermore, in addition to the above-mentioned various properties, it is excellent in workability such as kneading workability, roll workability, extruding workability, etc. In particular, the "gel" due to shear strain and heat history at the time of kneading work and extrusion work is removed. It is necessary that the sponge is not easily formed, and that the sponge surface is good, in order to reduce poor appearance of the product. Under such circumstances, various ethylene-α-olefin-non-conjugated diene copolymer rubber compositions having a bimodal molecular weight distribution composed of a low molecular weight component and a high molecular weight component have been proposed. However, in such a rubber composition, the number of factors that have a significant effect on the properties of the composition and the sponge rubber obtained therefrom is large, and these factors are complicatedly correlated. In fact, it is extremely difficult to select and combine. For example, JP-A-61-278540 discloses that
Ethylene / α-olefin weight ratio of 40/60 to 70 /
30, the content of low molecular weight components is 5 to 50% by weight,
A rubber composition having a viscosity (ML _{1 + 8} , 120 ° C.) of 50 to 110 is disclosed.
Although the general roll processability and extrusion processability are good, they are not satisfactory particularly from the viewpoint of suppressing the generation of "gel". Japanese Patent Application Laid-Open No. 4-80245 discloses ethylene / α-
The olefin weight ratio is 40 / 60-73 / 27, the iodine value is 10-36, the weight ratio between the low molecular weight component and the high molecular weight component is 51 / 49-80 / 20, and the low molecular weight component and the high molecular weight component are similar. A rubber composition having a prime value ratio of 1.1 / 1 to 4/1 and a Mooney viscosity (ML _{1 + 4 at} 121 ° C.) of 50 to 100 is disclosed. However, it is difficult to achieve a high degree of foaming, and the sponge properties are not sufficient. Furthermore, 2-6
No. 2582 discloses ethylene, α-olefin, 5-
Consisting of ethylidene-2-norbornene (ENB) and 5-vinyl-2-norbornene (VNB), ENB /
A copolymer rubber having a VNB molar ratio of 1/1 to 20/1 and a total content of ENB and VNB of 2 to 40 in elementary value like a copolymer, and having a specific molecular weight and a molecular weight distribution. Although sponge rubber having a particularly smooth surface is obtained, the copolymer rubber has a large compression set when highly foamed, and a "gel" during kneading or extrusion. There is a disadvantage that it is easy to occur. That is, in the conventional rubber composition for sponge, it has high foaming property, and furthermore, kneading processability, extrusion processability, shape retention during crosslinking / foaming,
The problem of comprehensively improving compression set and the like remains unsolved.

[0003]

DISCLOSURE OF THE INVENTION The present invention has a high foaming property at the time of foaming, and is excellent in workability. In particular, it is possible to suppress the formation of "gel" at the time of kneading processing and extrusion processing, and furthermore, when the foaming rate is high. It is an object of the present invention to provide an ethylene-α-olefin-non-conjugated diene copolymer rubber composition having excellent shape retention during crosslinking and foaming, and excellent compression set.

[0004]

The present invention comprises a low molecular weight component and a high molecular weight component, wherein the non-conjugated diene is ethylidene.
Norbornene as an essential component, and the following (1) to (6)
An ethylene-α-olefin-non-conjugated diene copolymer rubber composition satisfying the following conditions: (1) the ethylene / α-olefin weight ratio is 40 / 60-
70/30; (2) the iodine value of the low molecular weight component is 37 to 65, and the iodine value of the high molecular weight component is 10 to 55; (3) the iodine value ratio between the low molecular weight component and the high molecular weight component is 1 (4) iodine value is 15 to 45; (5) content of low molecular weight component is 5 to 50% by weight based on the total amount of low molecular weight component and high molecular weight component; 6) Mooney viscosity (ML _{1 + 8} , 120 ° C) 50 to 15
0 is the gist.

Hereinafter, the present invention will be described in detail. This will clarify the objects, configurations and effects of the present invention. Ethylene-α-olefin-non-conjugated diene copolymer rubber set
Composition as the present invention ethylene -α- olefin - non-conjugated diene copolymer rubber composition (hereinafter, referred to as "copolymer rubber composition".)
Wherein both the low molecular weight component and the high molecular weight component consist of an ethylene-α-olefin-non-conjugated diene copolymer. As the α-olefin in the ethylene-α-olefin-nonconjugated diene copolymer, for example, the carbon number of 3 to
12 α-olefins, specifically, propylene, butene-1, 3-methylbutene-1, pentene-1, 3-methylpentene-1, 4-methylpentene-1, 3-ethylpentene-1, hexene-1 , Octene-1, decene-
1, dodecene-1 and the like, and propylene is particularly preferred. These α-olefins can be used alone or in combination of two or more. The non-conjugated diene in the ethylene-α-olefin-non-conjugated diene copolymer contains ethylidene norbornene as an essential component and, in some cases, dicyclopentadiene as a copolymer component. When the non-conjugated diene in the ethylene-α-olefin-non-conjugated diene copolymer is dicyclopentadiene alone, the balance between the crosslinkability and the foaming property of the composition is lost, and a high foaming degree and a soft sponge rubber are obtained. It becomes difficult. Ethylene in copolymer rubber composition
The α-olefin weight ratio is from 40/60 to 70/30, preferably from 45/55 to 65/35. In this case, if the ethylene / α-olefin weight ratio is less than 40/60, the dispersion of the filler in the composition becomes insufficient and the sponge surface skin is damaged, and the strength of the sponge rubber also decreases. If it exceeds, the fluidity decreases and a large amount of energy is required at the time of kneading, and the material rubber is not sufficiently bitten by a roll or an extruder at the time of processing, which causes a problem in workability, and furthermore, the sponge rubber has Heat resistance also decreases. In the copolymer rubber composition, it is preferable that both the low molecular weight component and the high molecular weight component have the aforementioned ethylene / α-olefin weight ratio. In this case, the ethylene / α-olefin weight ratio in each component may be the same or different. In some cases, as long as the copolymer rubber composition satisfies the ethylene / α-olefin weight ratio condition, at least one of the low molecular weight component and the high molecular weight component may have an ethylene / α-olefin weight ratio outside the above range. it can. Next, the iodine value of the low molecular weight component is 3
It is 7-65, preferably 37-55, and the iodine value of the high molecular weight component is 10-55, preferably 10-40. In this case, if the element number is less than 37, such as a low molecular weight component, the compression set of the sponge rubber is impaired, and if it exceeds 65, it is difficult to highly foam. On the other hand, if the high molecular weight component has an element number of less than 10, the shape retention during crosslinking / foaming and the compression set of the sponge rubber are impaired, while if it exceeds 55, it is difficult to achieve high foaming. The iodine value ratio between the low molecular weight component and the high molecular weight component is
1.1 / 1 to 4/1, preferably 1.5 / 1 to 3.5 /
It is one. In this case, if the element number ratio is less than 1.1 / 1, a "gel" tends to be formed during processing, and the compression set of the sponge rubber is impaired. The shape retention at the time decreases. The iodine value of the copolymer rubber composition is 15 to 45, preferably 2
0 to 40. In this case, if the iodine value is less than 15,
High foaming becomes difficult, and the mechanical strength, cold resistance and the like of the sponge rubber are also reduced. On the other hand, even if it exceeds 45, high foaming becomes difficult. Next, the content of the low molecular weight component is 5 to 50% by weight, preferably 10 to 40% by weight, based on the total amount of the low molecular weight component and the high molecular weight component.
In this case, if the content of the low molecular weight component is less than 5% by weight, kneading processability, roll workability, extrusion processability, high foaming property, sponge rubber surface skin, etc. are deteriorated. Shape retention during foaming and sponge surface skin are impaired. These phenomena are due to the fact that low molecular weight components in the copolymer rubber composition greatly affect the viscosity of the composition during processing and foaming. Next, the Mooney viscosity (ML _{1 + 8} , 120 ° C.) of the copolymer rubber composition is 50 to 150, preferably 60 to 100. In this case, if the Mooney viscosity is less than 50, the shape retention at the time of crosslinking / foaming and the strength of the sponge rubber decrease, while if it exceeds 150, the kneading processability and the extrusion processability decrease. In the present invention, the Mooney viscosity of the low molecular weight component and the Mooney viscosity of the high molecular weight component are appropriately selected from the Mooney viscosity of the other component in accordance with the Mooney viscosity of one of the components, and are combined. The difference of (ML _{1 + 8} , 120 ° C.) is usually 20 or more, preferably 30 or more. The low molecular weight component and the high molecular weight component constituting the copolymer rubber composition of the present invention can be used alone or in combination of two or more.

[0006] Ethylene-α-olefin-non-conjugated diene
Production of copolymer Ethylene-α-olefin used in the present invention
The non-conjugated diene copolymer is prepared by a usual polymerization method using a medium / low pressure method, for example, in a suitable solvent, a Ziegler-Natta catalyst comprising a transition metal compound and an organometallic compound, for example, at least one solvent-soluble vanadium compound. In the presence of a catalyst comprising at least one organoaluminum compound, ethylene and an α-olefin are polymerized with a non-conjugated diene containing ethylidene norbornene as an essential component while supplying hydrogen as a molecular weight regulator as required. It can be manufactured by a method. The polymerization at that time can be carried out by a gas phase method (fluidized bed or stirred bed) or a liquid phase method (slurry method or solution method). As the solvent-soluble vanadium compound, VOCl ₃ , VCl ₄ , VOCl ₃
Alternatively, a reaction product of at least one of VCl ₄ and an alcohol is preferred. In this case, as the alcohol,
For example, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, t-butanol, n-hexanol, n-octanol, 2-ethylhexanol, n-decanol, n-decanol
Dodecanol and the like, in particular, having 3 to 8 carbon atoms
Are preferred. Examples of the organoaluminum compound include, for example, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, ethylaluminum sesquichloride, butylaluminum sesquichloride, ethylaluminum dichloride, butylaluminum Examples thereof include methylaluminoxane, which is a reaction product of dichloride and trimethylaluminum with water.Especially, ethylaluminum sesquichloride, butylaluminum sesquichloride, a mixture of ethylaluminum sesquichloride and triisobutylaluminum, triisobutylaluminum and butyl Mixtures with aluminum sesquichloride are preferred. Further, as the solvent, usually,
Hydrocarbon solvents are used; preferred hydrocarbon solvents are n
-Pentane, n-hexane, n-heptane, n-octane, isooctane, cyclohexane and the like. These hydrocarbon solvents can be used alone or in combination of two or more.

Preparation of Copolymer Rubber Composition The copolymer rubber composition of the present invention is prepared by blending the above-mentioned low molecular weight component and high molecular weight component as essential components and, if necessary, various additives described below. can do. In preparing the copolymer rubber composition, a usual kneader such as a Banbury mixer, a roll mixer, or an extruder can be used. In this case, the low molecular weight component and the high molecular weight component are mixed and supplied in advance. As a method of mixing the low molecular weight component and the high molecular weight component in advance, for example, (a) a method of mixing the solution of each component and then removing the solvent, and (b) using two polymerization tanks connected in series, Either one of the components is manufactured in the first polymerization tank, the polymerization product is supplied to the second polymerization tank, the other component is manufactured in the second polymerization tank, and then the solvent is removed. Can be. The copolymer rubber composition of the present invention is prepared by blending a filler, a softening agent, a crosslinking agent, a foaming agent, and the like, if necessary, to form a rubber compound, for example, by performing crosslinking and foaming by a commonly used method, Manufactured into sponge rubber. As the filler, for example, SRF, FEF, HAF, ISAF, S
Carbon blacks such as AF, FT, and MT; and inorganic fillers such as fine silica particles, calcium carbonate, magnesium carbonate, clay, and talc. These fillers can be used alone or in combination of two or more. The amount of the filler is usually 50 to 100 parts by weight of the total of the low molecular weight component and the high molecular weight component.
200 parts by weight. Further, as the softening agent, an aromatic oil usually used for rubber, naphthenic oil,
Process oils such as paraffin oil; vegetable oils such as coconut oil; Of these softeners, process oils are preferred, and paraffin oil is particularly preferred. These softeners can be used alone or in combination of two or more. The compounding amount of the softener is usually at least 30 parts by weight based on 100 parts by weight of the total of the low molecular weight component and the high molecular weight component. Examples of the crosslinking agent include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur; inorganic vulcanizing agents such as sulfur chloride, selenium, and tellurium; morpholine disulfides, alkylphenol disulfides, thiuram disulfides, Sulfur-containing organic compounds such as dithiocarbamic acids; 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 1,
Organic peroxides such as 3-bis (t-butylperoxy-isopropyl) benzene and the like can be mentioned. These crosslinking agents can be used alone or in combination of two or more. The amount of the cross-linking agent varies depending on the type of the cross-linking agent. For example, in the case of sulfur, the amount is usually 0.1 to 100 parts by weight in total of the low molecular weight component and the high molecular weight component.
It is 1 to 10 parts by weight, preferably 0.5 to 5 parts by weight.
When sulfur is used as a cross-linking agent, a vulcanization accelerator and a vulcanization accelerator may be further added as necessary. Examples of such a vulcanization accelerator include aldehyde ammonias such as hexamethylenetetramine and acetaldehyde ammonia; diphenylguanidine, di (o-tolyl)
Guanidines such as guanidine and o-tolyl-biguanide; thiocarbanilide, di (o-tolyl) thiourea,
Thioureas such as N, N'-diethylthiourea, tetramethylthiourea, trimethylthiourea, dilaurylthiourea; mercaptobenzothiazole, dibenzothiazole disulfide, 2- (4-morpholinothio) benzothiazole, 2- (2,4- Benzothiazoles such as dinitrophenyl) mercaptobenzothiazole and N, N '-(diethylthiocarbamoylthio) benzothiazole; Nt-butyl-2-benzothiazylsulfenamide, N, N'-dicyclohexyl-2- Sulfenamides such as benzothiazylsulfenamide, N, N'-diisopropyl-2-benzothiazylsulfenamide, N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide, tetraethylthiuram Thiurams such as disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide; zinc dimethylthiocarbamate, zinc diethylthiocarbamate, zinc di-n-butylthiocarbamate, ethylphenyldithiocarbamate Thiocarbamate salts such as zinc, sodium dimethyldithiocarbamate, copper dimethyldithiocarbamate, tellurium dimethylthiocarbamate and iron dimethylthiocarbamate;
Xanthates such as zinc butylthioxanthogenate and zinc isopropylxanthogenate can be mentioned. These vulcanization accelerators can be used alone or in combination of two or more. The compounding amount of the vulcanization accelerator is usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the total of the low molecular weight component and the high molecular weight component. Further, as the vulcanization accelerating aid, for example, magnesium oxide, zinc white, litharge,
Metal oxides such as red lead and white lead; organic acids such as stearic acid, oleic acid, and zinc stearate; and the like; zinc white and stearic acid are particularly preferable. These vulcanization accelerators can be used alone or in combination of two or more. The compounding amount of the vulcanization accelerator is based on 100 parts by weight of the total of the low molecular weight component and the high molecular weight component.
Usually, it is 0.5 to 20 parts by weight. When organic peroxides are used as the cross-linking agent, a cross-linking aid can be further added as necessary. Examples of such a crosslinking aid include sulfur and sulfur compounds such as sulfur and dipentamethylenethiuram tetrasulfide; polyethylene dimethacrylate, divinylbenzene, diallyl phthalate, triallyl cyanurate, metaphenylene bismaleimide, toluylene bismaleimide and the like. And oxime compounds such as p-quinone oxime and p, p'-benzoylquinone oxime. These crosslinking assistants can be used alone or in combination of two or more. Examples of the blowing agent include inorganic blowing agents such as ammonium carbonate, sodium bicarbonate, and anhydrous sodium nitrate; dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-dinitrosoterephthalamide, benzenesulfonyl. Organic foaming agents such as hydrazide, p, p'-oxybis (benzenesulfonyl hydrazide), 3,3'-disulfone hydrazide diphenyl sulfone, azoisobutyronitrile, azobisformamide and the like can be mentioned. These foaming agents can be used alone or in combination of two or more. Further, a foaming aid such as a urea-based, organic acid-based, or metal salt-based foaming agent can be used together with the foaming agent. The amount of the foaming agent and the foaming aid varies depending on the kind and the desired degree of foaming, but the foaming agent is usually added in an amount of 0.1 part by weight based on 100 parts by weight of the total of the low molecular weight component and the high molecular weight component.
It is 5 to 20 parts by weight, preferably 1 to 15 parts by weight, and the foaming aid is usually 1 to 20 parts by weight. further,
In the copolymer rubber composition of the present invention, if desired, a reinforcing material,
Hygroscopic agent, plasticizer, antioxidant, antioxidant, heat stabilizer,
Other additives such as ultraviolet absorbers, lubricants, release agents, flame retardants, antistatic agents, dyes and pigments, fungicides can be compounded,
Polymers other than those described above, for example, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, acrylic rubber, ethylene-α-olefin copolymer, other ethylene-α-olefin- Non-conjugated diene copolymers, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene and the like can also be blended. The method of compounding and the order of compounding each component in producing the sponge rubber are not particularly limited, and a kneader or an extruder can also be a known one.In particular, using a Banbury mixer, After kneading a molecular weight component, a high molecular weight component, a filler, a softener, and the like, it is preferable to knead a crosslinking agent, a foaming agent, and the like using a roll mixer. In addition, when compounding using an extruder, it is also possible to knead a part of the compounded components in advance using a Banbury mixer or the like and then supply them to the extruder, and then supply the remaining compounded components separately to the extruder and knead them. The components can be supplied to an extruder and kneaded. In such compounding, the compounding components other than the low molecular weight component, the high molecular weight component, the filler, the softener, the crosslinking agent and the foaming agent can be added at an appropriate kneading stage. Then, according to the procedure used in the production of ordinary sponge rubber, for example, a method of crosslinking and foaming the rubber compound by heating in a mold of a known crosslinking and foaming apparatus, or an extruder for the rubber compound. A desired sponge rubber can be produced by a method of forming the desired sponge rubber into a desired shape and then heating in a crosslinking tank. The heating temperature and the heating time at the time of crosslinking / foaming vary depending on the type of the crosslinking agent and the foaming agent, the degree of foaming, and the like. Is usually 2
１５15 minutes, preferably 3-10 minutes.

[0008]

The present invention will be described below more specifically with reference to examples and comparative examples. However, the present invention is not limited to these embodiments. Each measurement and evaluation in Examples and Comparative Examples was performed in the following manner. [1] Ethylene / propylene weight ratio Measured by infrared absorption spectroscopy. [2] Iodine value Measured by an infrared absorption spectrum method. [3] Mooney viscosity (ML _{1 + 8} , 120 ° C.) The viscosity was measured at a measuring temperature of 120 ° C., a residual heat time of 1 minute, and a time of 8 minutes until the viscosity was read. [4] Roll workability Compound (ii) of each Example and Comparative Example was treated at a temperature of 5
The film was wound around a 10-inch roll at 0 ± 5 ° C. with a nip width of 2 mm, and evaluated according to the following four grades based on the wound state shown in FIG. 1 and the time required for firm winding. Excellent: good: bad: not acceptable In FIG. 2, 1 is a rear roll, 2 is a front roll, and 3 is a compound (ii). [5] Extrusion processability (Garbe die rating) It was evaluated based on ASTM-D2230. [6] Shape Retention (%) A molded product obtained by extruding the compound (ii) of each Example and Comparative Example using a die having the shape shown in FIG. 2 was left horizontally in an atmosphere of 220 ° C. for 7 minutes. After that, it is cross-linked / foamed and left at room temperature.
The ratio was evaluated by the ratio (La / Lb) × 100 with b. [7] Gelation time About compound (i) of each Example and a comparative example,
Using a stress relaxation measurement device (JSR Elastograph, manufactured by Nippon Synthetic Rubber Co., Ltd., Japanese Patent Publication No. 5-25059), the gelation time is determined by the torque rise start time measured at 130 ° C. and a shear strain rate of 20 per second. And The longer the gelation time, the harder it is to form a "gel". [8] Physical properties of sponge Specific gravity Measured in accordance with the Japan Rubber Association Standards / Expansion Rubber Physical Test Method. Conform to compression set JIS K6301, the molded product was extruded using a die having a shape shown in FIG. 2, multiplied by the vertical direction to 50% of the compressive strain in FIG. 2, the compressive strain after 200 hours at 70 ° C. It was measured. Surface Skin Based on the smoothness of the surface of the sponge rubber, gloss, the presence or absence of adhesion, and the like, it was visually evaluated according to the following three grades. A: Normal: Not possible

Examples 1 to 7 and Comparative Examples 1 to 6 A mixture of a low molecular weight component and a high molecular weight component (hereinafter referred to as "rubber") shown in Table 1 (Examples 1 to 7) and Table 2 (Comparative Examples 1 to 6) Table 3 (Examples 1 to 7).
And the component [I] shown in Table 4 (Comparative Examples 1 to 6) were blended,
Using a BR type Banbury mixer (internal volume 1.7 liters), the mixture was kneaded at 130 rpm for 80 seconds at a rotation speed of 80 rpm to obtain a compound (i). To this compound (i), the components [II] shown in Table 3 (Examples 1 to 7) and Table 4 (Comparative Examples 1 to 6) were blended, and a 10-inch roll mixer kept at 50 ° C. was used. The mixture was kneaded for 5 minutes with the number of rotations of the front roll (rpm) / the number of rotations of the rear roll (rpm) = 24/22 to obtain a compound (ii). Then, the garbage die (ASTM-D233) was placed in a 50 mm extruder.
0), cylinder temperature 60 ° C,
The compound (ii) was extruded at a die temperature of 80 ° C. and a screw rotation speed of 30 rpm, and the extrudability was evaluated. A die having the shape shown in FIG. 2 was attached to a 50 mm extruder, the cylinder temperature was set at 60 ° C., the die temperature was set at 80 ° C., and the screw rotation speed was set at 30 rpm. 5 in hot air bath
The mixture was heated for one minute to perform crosslinking and foaming, thereby obtaining a sponge rubber. Table 3 (Examples 1 to 7) and Table 4 (Comparative Examples 1 to 7) show the evaluation results for each compound and sponge rubber.
It is shown in 6). As a result, the copolymer rubber composition of the present invention is:
It has high foaming properties, low sponge specific gravity, and excellent roll processability and extrusion processability, especially hard to generate "gel",
In addition, the sponge rubber has excellent shape retention at the time of crosslinking and foaming, and has a small compression set and a good surface texture. On the other hand, in Comparative Example 1, the Mooney viscosity (ML
_{(1 + 8} , 120 ° C.), it is inferior in roll processability and sponge surface skin, and has insufficient foaming and extrudability. In Comparative Example 2, the ethylene / propylene weight ratio was large and the Mooney viscosity (ML _{1 + 8} , 120 ° C.) was low. Further, Comparative Example 3 is particularly inferior in compression set because of a low element number like a rubber mixture. Further, Comparative Example 4 has a high element value like a rubber mixture, so it is easy to gel, and it is difficult to make the foam highly foamed. Also,
Comparative Example 5 has a low iodine value of the low molecular weight component and a low iodine ratio of the low molecular weight component and the high molecular weight component, and therefore easily gelates, and has insufficient foaming properties, roll processability, and extrudability. It is. Furthermore, Comparative Example 6 has a particularly low shape retention because of a large element number ratio between the low molecular weight component and the high molecular weight component.

[0010]

[Table 1]

[0011]

[Table 2]

In Tables 3 and 4, (* 1) to (* 11)
Is as follows. (* 1) Asahi Carbon Co., Ltd. Asahi 50HG (* 2) Asahi Carbon Co., Ltd. Asahi F200 (* 3) Idemitsu Kosan Co., Ltd. Diana Process Oil PW
-380 (* 4) Vesta PP manufactured by Inoue Lime Industry Co., Ltd. (* 5) Mercaptobenzothiazole (* 6) Zinc dimethyldithiocarbamate (* 7) Zinc di-n-butyldithiocarbamate (* 8) Dipentamethylenethiuram Tetrasulfide (* 9) Tetraethylthiuram disulfide (* 10) 4,4'-dithio-bis-dimorpholine (* 11) p, p'-oxybis (benzenesulfonylhydrazide)

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

The copolymer rubber composition of the present invention has a high foaming property at the time of foaming, is excellent in kneading processability, roll processability, and extruding processability, hardly generates a "gel", and has a high foaming property. When formed, it has excellent shape retention at the time of crosslinking and foaming, small compression set, good sponge surface texture, and excellent balance of properties. Therefore, the copolymer rubber composition of the present invention can be very suitably used as a sealing material for automobile door seals, roof side rails, trunk seals and the like, especially as a sponge rubber, and also for other transportation means. , Sealing materials for civil engineering and construction, general machinery
It is useful for a wide range of applications, including sealing materials for equipment, wire coating, and extruded products.

[Brief description of the drawings]

FIG. 1 is a view for explaining a wrapped state of a compound (ii) during roll processing.

FIG. 2 is a view showing the shape of a die used for evaluation of shape retention and compression set.

[Explanation of symbols]

 1 Back roll 2 Front roll 3 Compound (ii)

──────────────────────────────────────────────────の Continued on the front page (72) Fumio Tsutsumi, Inventor 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Yoji Mori 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (56) References JP-A-61-278540 (JP, A) JP-A-3-136825 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 23 / 16

Claims (1)

(57) [Claims] 1. A non-conjugated diene comprising ethylidene norbornene as an essential component, comprising a low molecular weight component and a high molecular weight component.
And an ethylene-α-olefin-non-conjugated diene copolymer rubber composition satisfying the following conditions (1) to (6). (1) Ethylene / α-olefin weight ratio is 40 / 60-
70/30; (2) the iodine value of the low molecular weight component is 37 to 65, and the iodine value of the high molecular weight component is 10 to 55; (3) the iodine value ratio between the low molecular weight component and the high molecular weight component is 1 (4) iodine value is 15 to 45; (5) content of low molecular weight component is 5 to 50% by weight based on the total amount of low molecular weight component and high molecular weight component; 6) Mooney viscosity (ML _{1 + 8} , 120 ° C) 50 to 15
0.