JP3191592B2 - 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 necessary that the material has excellent workability such as kneading workability, roll workability, and extruding workability, and particularly that a “gel” is hardly generated during kneading and extrusion. Existence and good extruded surface texture are also strictly required to reduce poor appearance of sponge rubber products. Under these circumstances, for example, JP-A-3-20339 discloses that the ethylene / α-olefin-nonconjugated diene copolymer rubber has an ethylene / α-olefin weight ratio of 73/27 to 40/60 and a Mooney viscosity ( ML _{1 + 4 (} 121 ° C.) is 135 to 200, and the non-conjugated diene content is 10 to 36 in terms of the prime value like a copolymer rubber. However, in such a method, since the molecular weight is high, the compound has a high viscosity and the foaming is difficult to achieve high foaming with a normal blending amount of carbon black and oil. Moreover, in order to achieve high foaming, a large amount of oil needs to be added, so that there is a disadvantage that shape retention is reduced. On the other hand, in a rubber composition comprising an ethylene-α-olefin-non-conjugated diene copolymer rubber, a method of improving a compression set particularly by combining a high molecular weight copolymer rubber component and a low molecular weight rubber component has also been attempted. For example, in Japanese Patent Application Laid-Open No. 4-80245, ethylene / α is composed of a low molecular weight copolymer and a high molecular weight copolymer.
-An olefin weight ratio of 73/27 to 40/60, an amount at which the diolefin content is 10 to 36 in iodine value, and an iodine value ratio of the low molecular weight copolymer to the high molecular weight copolymer of 1. Muni-viscosity (ML _{1 +} 41, which is 1/1 to 4/1)
(21 ° C.) 50 to 100. However, the rubber composition has a relatively small compression set and is excellent in extrusion processability and shape retention, but has a problem that it is difficult to achieve a high degree of foaming.
Furthermore, Japanese Patent Publication No. 2-62582 discloses ethylene, α
-Olefin, 5-ethylidene-2-norbornene (E
NB) and 5-vinyl-2-norbornene (VNB)
The ENB / VNB molar ratio is 1/1 to 20/1,
A copolymer rubber having a specific molecular weight and a specific molecular weight distribution in which the total content of ENB and VNB is 2 to 40 in elementary value like a copolymer is disclosed. However,
The copolymer rubber can give sponge rubber having a particularly smooth surface, but has a drawback that a "gel" is apt to be generated during kneading or extrusion. In other words, conventional sponge rubbers and sponge rubber compositions have high foaming properties, and generally improve kneading workability, extrusion workability, shape retention during crosslinking / foaming, compression set, etc. The challenge remains to be solved.

[0003]

SUMMARY OF THE INVENTION The present invention has a high foaming property at the time of foaming and a "gel" during kneading and extrusion.
Can be suppressed, and when highly foamed, ethylene is excellent in shape retention during cross-linking and foaming, and excellent compression set.
An object of the present invention is to provide an α-olefin-non-conjugated diene copolymer rubber composition.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, by combining a specific low molecular weight component copolymer and a high molecular weight component copolymer, the above problems have been solved. And found that an ethylene-α-olefin-non-conjugated diene copolymer rubber composition extremely useful as a sponge rubber was obtained, and completed the present invention. The present invention relates to (A) an ethylene / α-olefin weight ratio of 40/60 to
70/30, and the non-conjugated diene has an iodine value of 10 to 5
The amount of ethylidene norbornene is 0 and the amount of dicyclopentadiene is 0 to 20 in iodine number; the difference in iodine number between ethylidene norbornene and dicyclopentadiene is 10 to 40; (ML _{1 + 4} ,
(100 ° C.) 10-150, an ethylene-α-olefin-non-conjugated diene copolymer, and (B) an ethylene / α-olefin weight ratio of 50 / 50-
90/10, and the non-conjugated diene has an iodine value of 2 to 20.
1 in ethylidene norbornene and iodine value
It comprises dicyclopentadiene in an amount of from 0 to 40, has an element number ratio of ethylidene norbornene and dicyclopentadiene of 1/4 to 1/1, and has a Muni-viscosity (ML).
_{1 + 4} , 100 ° C.) is 100-500.
It contains an olefin-non-conjugated diene copolymer, the component (A) and the component (B) have an element number ratio of 0.5 to 1.1, and the component (A) has a Mooney viscosity of the component (B). weight of rather smaller than the Mooney viscosity and the components (a) and (B)
An ethylene-α-olefin-non-conjugated diene copolymer rubber composition characterized in that the quantitative ratio is 30/70 to 70/30 .

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 The ethylene-α-olefin-non-conjugated diene copolymer rubber composition of the present invention (hereinafter, referred to as “copolymer rubber composition”).
Is a low molecular weight component copolymer (A) ethylene-α-
An olefin-non-conjugated diene copolymer (hereinafter, referred to as “component (A)”) and (B) an ethylene-α-olefin-non-conjugated diene copolymer (hereinafter, referred to as “component (A)”) forming a high molecular weight component copolymer (B) ”). In the components (A) and (B), examples of the α-olefin include α-olefins having 3 to 12 carbon atoms, 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 component (A) and the component (B) consists of ethylidene norbornene and dicyclopentadiene.

[0006] Component (A) an ethylene / alpha-olefin weight ratio of component (A) is 40 / 60-70 / 30, preferably 45 /
55-65 / 35. In this case, if the weight ratio of ethylene / α-olefin is less than 40/60, the dispersion of the filler in the composition becomes insufficient and sponge surface skin is impaired, and the strength of sponge rubber also decreases.
If it exceeds 300, the compression set of the sponge rubber at low temperature is impaired. Further, the copolymerization amount of ethylidene norbornene in the component (A) is 1 unit in element number as in the component (A).
The amount is from 0 to 50, preferably from 15 to 45. In this case, if the copolymerization amount of ethylidene norbornene is less than 10 in iodine value, the compression set of the sponge rubber is impaired, and the crosslinking speed is reduced. On the other hand, if the iodine value exceeds 50, "gel" is likely to occur during kneading and extrusion, and the balance between the crosslinking speed and the foaming speed is disturbed, resulting in high foaming. It becomes difficult and the cost increases. In addition, component (A)
The copolymerization amount of dicyclopentadiene in the above is an amount such that the element number becomes 0 to 20 as in the component (A), preferably 0 to 20.
The amount is 15. In this case, when the copolymerization amount of dicyclopentadiene exceeds 20 in iodine value, the extrudability decreases. The difference in iodine value between ethylidene norbornene and dicyclopentadiene in the component (A) is 1
0 to 40. In this case, when the difference in the element numbers is less than 10, the extrudability is deteriorated. On the other hand, when it exceeds 40, the shape retention during crosslinking / foaming is impaired. Further, the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the component (A) is 10 to 10.
150, preferably 30-100. In this case, if the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the component (A) is less than 10, the shape retaining property is deteriorated at the time of crosslinking / foaming, and the sponge surface is deteriorated due to outgassing. Fifteen
If it exceeds 0, it will be difficult to achieve high foaming, and the kneading processability and the extrusion processability will also decrease. In the present invention, the component (A) can be used alone or in combination of two or more.

Component (B) Next, the ethylene / α-olefin weight ratio in component (B) is 50/50 to 90/10, preferably 6/50.
0/40 to 85/15. In this case, ethylene / α
If the olefin weight ratio is less than 50/50, the extrudability decreases, while if it exceeds 90/10, the compression set of the sponge rubber, especially at low temperatures, is impaired. The copolymerization amount of ethylidene norbornene in the component (B) is as follows:
The amount is such that the element value is 2 to 20, preferably 5 to 20, as in the component (B). In this case, if the copolymerization amount of ethylidene norbornene is less than 2 in iodine value, the compression set of the sponge rubber is impaired, and the crosslinking speed is reduced, resulting in deterioration of the sponge surface skin due to outgassing. If the prime value exceeds 20, "gel" is liable to occur during kneading and extrusion. In addition, the copolymerization amount of dicyclopentadiene in the component (B) is determined based on the amount of the component (B)
And an amount giving a prime value of 10 to 40, preferably 10 to 3
It is an amount that becomes zero. In this case, if the copolymerization amount of dicyclopentadiene is less than 10 in iodine value, the shape retention at the time of crosslinking / foaming decreases, while if the iodine value exceeds 40, the extrusion processability decreases. The iodine value ratio between ethylidene norbornene and dicyclopentadiene in the component (B) is 1/4 to 1/1. In this case, if the element number ratio is less than 1/4, the extrudability is reduced, while the ratio is 1/1.
When it exceeds, "gel" tends to be generated during kneading and extrusion. Further, the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the component (B) is from 100 to 500, preferably from 120 to 400. In this case, when the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the component (B) is less than 100,
When cross-linking / foaming, the sponge surface deteriorates due to a decrease in shape retention and outgassing, and the compression set of sponge rubber is impaired. On the other hand, when the sponge rubber exceeds 500, it becomes difficult to highly foam, and kneading processing is also performed. And extrusion processability also decrease. In the present invention, the component (B) can be used alone or in combination of two or more.

Production of Component (A) and Component (B) Component (A) and component (B) can be prepared by a conventional polymerization method using a medium / low pressure method, for example, by adding a transition metal compound and an organometallic compound in an appropriate solvent. A Ziegler-Natta catalyst consisting of, for example, ethylene, α-olefin, ethylidene norbornene and dicyclopentadiene in the presence of a catalyst consisting of at least one solvent-soluble vanadium compound and at least one organoaluminum compound. It can be produced by a method of performing polymerization while supplying hydrogen as a molecular weight regulator. 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). Examples of the solvent-soluble vanadium _{compound, VOCl 3, VCl 4, VOCl} 3 or the reaction product of at least one alcohol of VCl ₄ is preferred. In this case, examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol,
Examples thereof include t-butanol, n-hexanol, n-octanol, 2-ethylhexanol, n-decanol and n-dodecanol, and alcohols having 3 to 8 carbon atoms are particularly preferable. 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. As the solvent, a hydrocarbon solvent is usually used, and a preferred hydrocarbon solvent is 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.

Copolymer Rubber Composition The copolymer rubber composition of the present invention contains the above-mentioned components (A) and (B) as essential components and, if necessary, contains various additives described below. . In the copolymer rubber composition of the present invention, the iodine ratio of the component (A) to the component (B) is 0.5 to 1.1, preferably 0.9 to 1.05. In this case, when the element value ratio is out of the above range, it is difficult to secure a balance among high foaming properties, extrudability, shape retention during crosslinking and foaming, compression set of sponge rubber, and the like. Further, the Mooney viscosity (ML _{1 + 4} , 1) of the component (A)
00 ° C.) is the Mooney viscosity (ML _{1 + 4} , 10) of component (B).
0 ° C). In this case, when the Mooney viscosity of the component (A) is equal to or higher than the Mooney viscosity of the component (B), a "gel" is easily generated during kneading and extrusion. The weight ratio of the components (A) and (B) is preferably 30 / 70-70 / 30. In this case, if the weight ratio is less than 30/70, high foaming becomes difficult, and the kneading processability and the extruding processability tend to decrease. Retention is impaired, and the low elongation stress of sponge rubber tends to decrease. In preparing the copolymer rubber composition, a conventional kneader such as a Banbury mixer, a roll mixer, or an extruder can be used. In this case, the components (A) and (B) are mixed separately or in advance. Can be supplied. As a method of previously mixing the component (A) and the component (B), for example, (a) a method of melt-kneading the component (A) and the component (B), (b) a solution of the component (A) and a component (A) (C) a method of removing the solvent after mixing with the solution of (B), using two polymerization tanks connected in series,
Either component (A) or component (B) was produced in the first polymerization vessel, the polymerization product was supplied to the second polymerization vessel, and the other component was produced in the second polymerization vessel. Thereafter, a method of removing the solvent can be used.

The copolymer rubber composition of the present invention is prepared by mixing a filler, a softening agent, a cross-linking agent, a foaming agent and the like, if necessary, into a rubber compound. Go on and manufacture into sponge rubber. As the filler, for example, SRF, FEF, HAF, ISA
Carbon blacks such as F, SAF, FT, and MT; particulate silica, calcium carbonate, magnesium carbonate, clay,
An inorganic filler such as talc can be used. 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 in total of the component (A) and the component (B).
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 blending amount of the softener is determined based on the component (A)
With respect to 100 parts by weight of the total of
0 to 150 parts by weight. Further, as the crosslinking agent,
For example, sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur; inorganic vulcanizing agents such as sulfur chloride, selenium, and tellurium; sulfur-containing organic compounds such as morpholine disulfides, alkylphenol disulfides, thiuram disulfides, and dithiocarbamic acids 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, di-tert-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 crosslinking agent varies depending on the type of the crosslinking agent. For example, in the case of sulfur, 0.1 to 100 parts by weight of the total of the component (A) and the component (B) is usually 0.1 to 100 parts by weight.
It is 10 parts by weight, preferably 0.5 to 5 parts by weight. When using sulfur as a cross-linking agent, if necessary, a vulcanization accelerator,
A vulcanization accelerator may be further added. Examples of such a vulcanization accelerator include aldehyde ammonias such as hexamethylenetetramine and acetaldehyde ammonia; guanidines such as diphenylguanidine, di (o-tolyl) guanidine, o-tolyl-biguanide; thiocarbanilide and di (o- Tolyl) thiourea, N,
N′-diethylthiourea, tetramethylthiourea,
Thioureas such as trimethylthiourea and dilaurylthiourea; mercaptobenzothiazole, dibenzothiazole disulfide, 2- (4-morpholinothio) benzothiazole, 2- (2,4-dinitrophenyl) mercaptobenzothiazole, N, N'- Benzothiazoles such as (diethylthiocarbamoylthio) benzothiazole; Nt-butyl-2-benzothiazylsulfenamide, N, N'-dicyclohexyl-2-benzothiazylsulfenamide, N, N'- Diisopropyl-
Sulfenamides such as 2-benzothiazylsulfenamide and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, dipenta Thiurams such as methylenethiuram tetrasulfide; zinc dimethylthiocarbamate, zinc diethylthiocarbamate, zinc di-n-butylthiocarbamate, zinc ethylphenyldithiocarbamate, sodium dimethyldithiocarbamate, copper dimethyldithiocarbamate, dimethylthiocarbamine Thiocarbamate salts such as tellurium acid and iron dimethylthiocarbamate; xanthos such as zinc butylthioxanthate and zinc isopropylxanthate Phosphate salts and the like can be mentioned. These vulcanization accelerators can be used alone or in combination of two or more. The amount of the vulcanization accelerator is usually 0.1 to 20 parts by weight, preferably 0.2 to 20 parts by weight, based on 100 parts by weight of the total of the component (A) and the component (B).
10 parts by weight. Further, as the vulcanization accelerator,
Examples thereof include metal oxides such as magnesium oxide, zinc white, litharge, lead red and white lead; and organic acids such as stearic acid, oleic acid, zinc stearate and the like, and 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 accelerating aid is usually 0.5 to 100 parts by weight of the total of the component (A) and the component (B).
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 hydrazide, p, p'-oxybis (benzenesulfonyl hydrazide), 3,3 '
-Organic blowing agents such as disulfone hydrazide diphenyl sulfone, azoisobutyronitrile, azobisformamide and the like. 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 auxiliary varies depending on the type and the desired degree of foaming. However, the amount of the foaming agent is usually 0 to 100 parts by weight of the total of the components (A) and (B). 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight.
-20 parts by weight. Further, in the copolymer rubber composition of the present invention, if desired, a reinforcing material, a moisture absorbent, a plasticizer, an antioxidant, an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant, a release agent, a flame retardant, Other additives such as antistatic agents, dyes and pigments, fungicides and the like can be blended, and 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 copolymer, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, Polypropylene or the like may be blended. The compounding method and the compounding order of each component when producing the sponge rubber are not particularly limited, and a kneader or an extruder can also use a known one.
In particular, it is preferable to knead the components (A) and (B), the filler, the softener and the like using a Banbury mixer, and then knead the crosslinking agent and the foaming agent 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 components (A) and (B), 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 rubber compound
The desired sponge rubber is manufactured by a method of crosslinking and foaming by heating in a mold of a foaming device, or a method of forming a rubber compound into a desired shape using an extruder and then heating the compound in a crosslinking tank. be able to. The heating temperature and heating time at the time of crosslinking and foaming vary depending on the type of the crosslinking agent and the foaming agent, the degree of foaming, and the like.
The temperature is 0 ° C, preferably 180 to 250 ° C, and the heating time is usually 2 to 15 minutes, preferably 3 to 10 minutes.

[0011]

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 according to the following procedures. (1) Ethylene / propylene weight ratio Measured by an infrared absorption spectrum method. (2) Iodine value Measured by an infrared absorption spectrum method. (3) Mooney viscosity (ML _{1 + 4} , 100 ° C.) Measurement was performed at a measurement temperature of 100 ° C., a residual heat time of 1 minute, and a time of 4 minutes until the viscosity was read. (4) Extrusion processability (Garve die rating) The extrudability was evaluated based on the ASTM-D2230A method. (5) Shape Retention Shape Retention (%) A molded product obtained by extruding an uncrosslinked rubber compound using a die having the shape shown in FIG. 1 was allowed to stand horizontally at 220 ° C. for 7 minutes, and then crosslinked. After foaming and leaving at room temperature, the ratio of the vertical dimension La to the horizontal dimension Lb at room temperature (La / Lb) ×
100, the shape retention (%) was evaluated. Residual stress ratio R (t = 1 sec) Compound (i) obtained by blending component [I] of Table 2 with a mixture of component (A) and component (B) shown in Table 1,
Using a sample molded to a thickness of 6 mm and a diameter of 13 mm, 100 ° C
In the above, a compressive strain rate of 20% was applied, and a stress residual rate R (t = 1 sec) after 1 second was measured. Stress residual ratio R (t = 1se
The larger the value of c), the better the shape retention. (6) Gelation time The compound (i) was subjected to a stress relaxation measurement device (JSR Elastograph, manufactured by Japan Synthetic Rubber Co., Ltd., Japanese Patent Publication No. 5-25059) at 130 ° C. and a shear strain rate of 20 per second. The gelation time was defined as the temperature at which the torque started to increase measured in the above section. The longer the gel time,
Indicates that it is difficult to generate a "gel". (7) Sponge physical properties Specific gravity Measured in accordance with the Japan Rubber Association Standard Standards / Physical test method for expanded rubber. Compression set In accordance with JIS K6301, a molded product extruded using a die having the shape shown in FIG. 1 is subjected to a compression strain of 50% in the longitudinal direction of FIG. 1, and the compression strain after 70 hours at 70 ° C. It was measured. Surface Skin Based on the smoothness, gloss, and the presence or absence of adhesion of the surface of the sponge rubber, the evaluation was visually made into three grades of excellent: 、, normal: Δ, and poor: ×.

Examples 1-2 and Comparative Examples 1-3 A mixture of the component (A) and the component (B) shown in Table 1 was blended with the component [I] shown in Table 2 to obtain a BR type Banbury mixer. (Content: 1.7 liters) and rotation speed 80r
The mixture was kneaded at 130 ° C. for 200 seconds to obtain a compound (i). For this compound (i), Table 2
Using a 10-inch roll mixer maintained at 50 ° C., the component [II] shown in
Thereafter, the mixture was kneaded for 5 minutes with the number of rotations of the roll (rpm) = 24/22 to obtain a compound (ii). Then 50mm
The extruder was equipped with a garbage die (according to ASTM-D2330), and the cylinder temperature was 60 ° C and the die temperature was 80.
The compound (ii) was extruded at a temperature of 30 ° C. and a screw rotation speed of 30 rpm, and the extrudability was evaluated.
Also, a die having the shape shown in FIG. 1 was attached to a 50 mm extruder,
After extruding the compound (ii) at a cylinder temperature of 60 ° C., a die temperature of 80 ° C., and a screw rotation speed of 30 rpm, the mixture was heated in a hot-air bath at 250 ° C. for 3 minutes to perform crosslinking and foaming. I got the rubber. Table 2 shows the evaluation results for each compound and sponge rubber.
Shown in As a result, the copolymer rubber composition of the present invention has high foaming properties, low sponge specific gravity, and extrudability,
The sponge rubber is excellent in shape retention and hard to gel, and the sponge rubber has a small compression set and a good surface skin. On the other hand, Comparative Example 1 had a high sponge specific gravity because the copolymerization amount of ethylidene norbornene of the component (B) and the iodine value ratio of ethylidene norbornene to dicyclopentadiene were out of the range of the present invention. It is easy to form, the shape retention is low, and the extrusion processability is insufficient. In Comparative Example 2, the sponge specific gravity was large, the shape retention was low, and the compression set of the sponge rubber was low because the element ratios of the component (A) and the component (B) were out of the range of the present invention. It is large and the extrusion processability is insufficient. further,
Comparative Example 3 shows that the Mooney viscosity of the component (B) (ML _{1 + 4} , 10
(0 ° C.) is out of the range of the present invention, so that the shape retention is low, the compression set of the sponge rubber is large, and the surface of the sponge surface is insufficient.

[0013]

[Table 1]

[0014]

[Table 2]

In Table 2, (* 1) to (* 11) are 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 (* 5) Mercaptobenzothiazole (* 6) Zinc dimethyldithiocarbamate (* 7) Zinc di-n-butyldithiocarbamate (* 8) Dipentamethylenethiuram Tetrasulfide (* 9) Tetraethylthiuram disulfide (* 10) Morpholine disulfide (* 11) p, p'-oxybis (benzenesulfonylhydrazide)

[0016]

The copolymer rubber composition of the present invention has a high foaming property at the time of foaming, and is excellent in kneading processability and extruding processability.
In addition, when it is difficult to generate a “gel”, and when highly foamed,
It has excellent shape retention during cross-linking and foaming, low compression set, good sponge surface texture, and an excellent balance of properties. Therefore, the copolymer rubber composition of the present invention,
In particular, it can be very suitably used as a sponge rubber, as a sealing material for automobile door seals, roof side rails, trunk seals, etc., as well as other transportation sealing materials, civil engineering and building sealing materials, general machinery and equipment. It is useful for a wide range of applications including sealing materials for wires, wire coating, extruded products, etc.

[Brief description of the drawings]

FIG. 1 is a view showing the shape of a die used for evaluation of shape retention and compression set.

──────────────────────────────────────────────────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. (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 23/16

Claims (1)

(57) [Claims] (A) an ethylene / α-olefin weight ratio of 40/60 to 70/30, an amount of ethylidene norbornene in which an unconjugated diene has an iodine value of 10 to 50, and an amount of 0 to 0 in an iodine value; 20 in the amount of dicyclopentadiene, and the difference in the element number between ethylidene norbornene and dicyclopentadiene is 10 to 40;
An ethylene-α-olefin-nonconjugated diene copolymer having a viscosity (ML _{1 + 4} , 100 ° C.) of 10 to 150, and (B) an ethylene / α-olefin weight ratio of 50/50 to
90/10, and the non-conjugated diene has an iodine value of 2 to 20.
1 in ethylidene norbornene and iodine value
It comprises dicyclopentadiene in an amount of from 0 to 40, has an element number ratio of ethylidene norbornene and dicyclopentadiene of 1/4 to 1/1, and has a Muni-viscosity (ML).
_{1 + 4} , 100 ° C.) is 100-500.
It contains an olefin-non-conjugated diene copolymer, the component (A) and the component (B) have an element number ratio of 0.5 to 1.1, and the component (A) has a Mooney viscosity of the component (B). weight of rather smaller than the Mooney viscosity and the components (a) and (B)
An ethylene-α-olefin-non-conjugated diene copolymer rubber composition having a quantitative ratio of 30/70 to 70/30 .