JPS6124417B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a foam using an ethylene-α-olefin-diolefin copolymer rubber. Foamed products using ethylene-α-olefin-diolefin copolymer rubber as a rubber component take advantage of the copolymer rubber's excellent ozone resistance, heat resistance, weather resistance, etc., and can be used as sealing materials for automobiles and for civil engineering and construction. Used for sealing materials, etc. Foams used for these purposes are produced by first mixing the copolymer rubber, a softener, a filler, etc. using a mixer such as a Banbury mixer (the mixture obtained in this step is hereinafter referred to as compound A). ), furthermore,
A foaming agent and a vulcanizing agent are added to Compound A to prepare a foam compound (hereinafter, the compound obtained in this step will be referred to as Compound B). At this time, a compound for foam (compound B) is prepared in order to blend a vulcanizing agent and a blowing agent into rubber at a low temperature of 40 to 80°C without causing reactions such as foaming or vulcanization. In this case, a roll such as an open roll is usually used. Compound B thus obtained is vulcanized and foamed into a product by using a mold or by molding it into a certain shape and then heating it in a vulcanization system by free expansion without using a mold. . This method of manufacturing a foam by free expansion without using a mold involves continuously molding compound B into a certain shape using an extruder, and then introducing it into a vulcanization tank. Since it is possible to produce a large amount of foam with a certain shape and a certain quality per unit time, it is an excellent manufacturing process that can provide sealing materials for automobiles and sealing materials for civil engineering and construction at low cost. The present invention relates to ethylene-α-olefin-
The present invention relates to a method of producing a foam using a diolefin copolymer rubber as a rubber component of a material for a foam, particularly by free expansion. There are various proposals regarding methods for producing foams using ethylene-α-olefin-diolefin copolymer rubber. However, conventional methods, particularly methods for producing foams by free expansion, have various problems. For example, Japanese Patent Publication No. 52-26541 discloses an ethylene-α-olefin containing 25 to 85 mol% of ethylene units and a Mooney viscosity of 10 to 30.
This method uses diolefin copolymer rubber as the rubber component of sponge rubber, and there are no particular technical problems in production if a large amount of softener is not used. Due to the large amount of rubber used, the product foam is relatively expensive. On the other hand, when using a large amount of softener, use compound A.
The green strength (hereinafter abbreviated as GS) of Compound B was extremely reduced, resulting in the compound sagging during processing, poor winding on rolls, and free expansion during the vulcanization/foaming process, causing the foam to deteriorate. In the case of manufacturing, since the strength of the molded product made from Compound B is low, when the molded product is heated in a vulcanization tank at, for example, 180 to 260°C to vulcanize and foam, the vulcanization and foaming may be difficult. It has the disadvantage that it deforms due to its own weight before it is completed, that is, it loses its shape and cannot maintain its intended shape. On the other hand, in order to obtain Compound B with a high GS that does not cause deformation during the vulcanization and foaming process due to free expansion, it is necessary to use an ethylene-α-olefin-diolefin copolymer rubber with an extremely high Mooney viscosity. Ethylene-α-olefin-diolefin copolymer rubber has low fluidity not only in winter, so it requires wasted energy in the process of obtaining Compound A, and the resulting Compound A also has low fluidity and is difficult to use in the rolling process. Compound A deteriorates in workability, such as poor biting into the roll. Of course, it is possible to improve the biting into the roll by increasing the amount of softener blended, but
Compound A and Compound B have poor roll winding due to a decrease in GS, and deformation occurs during vulcanization and foaming due to free expansion, and furthermore, the strength of the obtained foam is weak. Ethylene-α- containing 75 mol% or more of ethylene units with increased strength due to the crystallinity of the ethylene chain
There is also a method of using olefin-diolefin copolymer rubber, but with this method, the strength of Compound A and Compound B at room temperature is certainly strong, but the ethylene chains melt at the roll temperature during roll processing, and the The winding is not improved. Although the drawback of deformation during vulcanization and foaming due to free expansion is somewhat improved, it is still insufficient. Furthermore, the fluidity of such ethylene-α-olefin-diolefin copolymer rubber decreases when exposed to low temperatures such as in winter, which increases the load on the mixer during the process of manufacturing compound A.
Mixing requires wasteful energy, and when the obtained compound A is rolled, there are problems in workability, such as poor biting into the roll. The purpose of the present invention is to provide a method for solving these drawbacks, that is, a method for producing a foam from an ethylene-α-olefin-diolefin copolymer rubber blended with a softener if necessary, which also solves processing problems. Instead, it is an object of the present invention to provide a method for manufacturing a foam without causing deformation even when vulcanization and foaming are performed by free expansion. Therefore, the present inventor investigated the relationship between the composition of the ethylene-α-olefin-diolefin copolymer rubber used as the rubber component of the foam material, the Mooney viscosity, etc., and the GS of Compound A and Compound B, and furthermore, the relationship between these and the GS of Compound A and Compound B. As a result of deep investigation into the relationship between processability and deformation during free expansion, we found that ethylene-α-olefin-diolefin copolymer rubber A with an ethylene unit content of 73 mol% or more and ethylene-α-olefin copolymer rubber A with an ethylene unit content of 73 mol% or less -Olefin-diolefin copolymer rubber B is mixed in a solution state at a weight ratio of 75/25 to 5/95, and the average composition of the mixture is 55 to 73 mol% of ethylene units, and Mooney viscosity (ML _1+4). , 121℃)
The inventors have discovered that the above-mentioned problems can be solved by using copolymer rubber C adjusted to have a coefficient of 65 to 120 as the rubber component of the foam material, leading to the present invention. In the present invention, ethylene-α-olefin-diolefin copolymer rubber A (hereinafter referred to as copolymer rubber A) has an ethylene unit content of 73 mol% or more and ethylene-α-olefin-diolefin copolymer rubber B has an ethylene unit content of 73 mol% or less. (Hereinafter abbreviated as copolymer rubber B.)
are mixed in a solution in the specified proportions, and the average composition of the mixture is 55 to 73 mol% of ethylene units.
Contains and Mooney viscosity (ML ₁₊₄ , 121℃)
It is essential to use a copolymer rubber C adjusted to have a molecular weight of 65 to 120, and the ethylene unit content is 55 to 73 mol% and the Mooney viscosity (ML ₁₊₄ , 121°C) is 55 to 73 mol%. Ethylene-.alpha.-olefin-diolefin copolymer rubber having a molecular weight of 65 to 120 generally has poor processability and also suffers from deformation during free expansion. In addition, the weight ratio of copolymer rubber A with an ethylene unit content of 73 mol% or more and copolymer rubber B with an ethylene unit content of 73 mol% or less is 75/
Even if a mechanical mixture of 25 to 5/95 is used as a rubber component for foam materials, not only will the problem of workability and deformation be solved, but the produced foam will There are significant quality deviations in density and strength. The copolymer rubber A used in the present invention is a copolymer rubber composed of ethylene, α-olefin, and diolefin containing 73 mol% or more, preferably 75 to 90 mol%, of ethylene units. The α-olefins include propylene, 1-butene, 1-
Pentene-1,4-methyl-1-pentene, 1-
Examples include hexene and 1-octene, among which propylene and 1-butene are preferred, with propylene being particularly preferred. The content of α-olefin units in copolymer rubber A is 27 mol% or less, preferably 4 to 27 mol%.
Diolefins include isoprene, butadiene,
1,4-pentadiene, 1,4-hexadiene,
Examples include divinylbenzene, dicyclopentadiene, methylene norbornene, ethylidene norbornene, among which dicyclopentadiene, 1,4-hexadiene and ethylidene norbornene are preferably used, and ethylidene norbornene is particularly preferably used. The content of diolefin units in copolymer rubber A is 0.5 to 10 mol%
The content is preferably 1.0 to 5 mol%, particularly preferably 1.0 to 5 mol%. The content of diolefin in terms of iodine value is preferably 4 to 75, particularly preferably 8 to 40. In addition, the Mooney viscosity (ML ₁₊₄ , 121℃) of copolymer rubber A is 10 or more.
Preferably it is 300. On the other hand, copolymer rubber B has 73 mol% of ethylene units.
Hereinafter, a copolymer rubber consisting of ethylene, α-olefin and diolefin, preferably containing 50 to 70 mol%. The α-olefin and diolefin used in copolymer rubber B are the same as those for copolymer rubber A, and the content of α-olefin units in copolymer rubber B is 17 mol% or more. It is preferably 50 to 50 mol%. Further, the content of diolefin units is preferably 0.5 to 10 mol%, particularly 1.0 mol%.
It is preferably from 5 mol % to 5 mol %. If the content of diolefin is expressed by iodine value, it is 4 to 4.
75 is preferred, and 8 to 40 is particularly preferred. Also, Mooney viscosity of copolymer rubber B (ML ₁₊₄ , 121℃)
is preferably 10 to 300. Copolymer rubber A and copolymer rubber B used in the present invention are produced by a known method. That is, in a medium, ethylene,
It is produced by supplying α-olefin, diolefin, and, if necessary, hydrogen gas as a molecular weight regulator. Examples of the medium include pentane, hexane, heptane, octane,
Aliphatic hydrocarbons such as kerosene, cycloaliphatic hydrogens such as cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, chlorobenzene, carbon tetrachloride, tetrachloroethylene, trichlorethylene, ethyl chloride, Halogenated hydrocarbons such as methylene chloride and dichloroethane can be used alone or in combination. Furthermore, the α-olefin used in the copolymerization reaction can be used in large excess as a reaction medium. Examples of soluble vanadium compounds include vanadium tetrachloride, vanadyl trichloride, vanadium triacetylacetonate, vanadyl diacetylacetonate, vanadyl trialkoxide VO(OR) ₃ (where R represents an aliphatic hydrocarbon group), Halogenated vanadyl alkoxide VO (OR) _o X _3-o (where R is an aliphatic hydrocarbon group, X is a halogen atom, and 0
<n<3. ) can be used alone or in combination. On the other hand, organic aluminum compounds include compounds represented by the general formula R _n AlX _3-n (where R is an aliphatic hydrocarbon group, X is a halogen, and 1≦m≦3), such as triethylaluminum. ,
Diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, and the like can be used alone or in combination. Copolymer rubber C of the present invention is obtained by mixing copolymer rubber A and copolymer rubber B in a solution in a weight ratio of 75/25 to 5/95, preferably 60/40 to 15/85. 55 ethylene units as average composition
Contains 60 to 73 mol%, preferably 60 to 70 mol%, and has a Mooney viscosity (ML ₁₊₄ , 121°C) of 65 to 73 mol%.
120, preferably 65 to 110. The α-olefin unit content of the copolymer rubber C is 27 to 45 mol%, preferably 30 to 40 mol%, and the diolefin unit content is 0.5 to 10 mol%, preferably 1 to 5 mol%. The diolefin unit content in terms of iodine value is 4 to 75, preferably 8 to 75.
It is 40. In the present invention, the rubber solution for mixing copolymer rubber A and copolymer rubber B is such that copolymer rubber A and copolymer rubber B are dissolved in a solvent in a weight ratio of 75/25 to 5/95. However, the first method for preparing such a rubber solution is to use copolymer rubber A.
An example of the method is to dissolve copolymer rubber A and copolymer B in a predetermined ratio in a solvent that can dissolve both of copolymer rubber A and copolymer rubber B. Examples of solvents that can dissolve copolymer rubber A and copolymer rubber B include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, and kerosene; alicyclic carbonates such as cyclopentane and cyclohexane; Hydrogen: Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene, cymene, mesitylene; Chlorobenzene, dichlorobenzene, trichlorobenzene, bromobenzene, dibromobenzene, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene and mixtures thereof. A rubber solution is obtained by mixing these solvents with copolymer rubber A and copolymer rubber B, and heating and stirring as necessary. Of course, solutions containing copolymer rubber A or copolymer rubber B may be prepared separately and then mixed. Even if ethylene-α-olefin-diolefin copolymer rubbers with different ethylene compositions are mixed, the additivity of the ethylene composition is achieved, and ethylene-α-olefin-diolefin copolymer rubbers with different Mooney viscosities are mixed. Since the Mooney viscosity correlation diagram for the mixed system can be obtained in advance, it is possible to determine in what proportions copolymer rubber A and copolymer rubber B should be used in order to obtain copolymer rubber C having the intended composition and Mooney viscosity. The strength can be easily known in advance. Of course, the proportion of copolymer rubber A and copolymer rubber B used must not exceed a polymerization ratio of 75/25 to 5/95. Copolymer rubber A as a second method for preparing a rubber solution
Alternatively, a method may be mentioned in which copolymer rubber B is prepared by the above-described manufacturing method to prepare a polymer solution containing each copolymer rubber and then mixed. In this case, a polymerization solution containing one of the copolymer rubbers is prepared in a reactor, the polymerization solution is stored in another reactor, and then a polymerization solution containing the other copolymer rubber is prepared in the same reactor. After preparing the respective polymerization solutions, it is possible to mix each polymerization solution, or alternatively, after preparing each polymerization solution containing copolymer rubber A or copolymer rubber B in two reactors installed in parallel, each polymerization solution may be mixed. The polymerization solution may be mixed. In addition, when using this method, each polymerization solution may be mixed when the catalyst in each polymerization solution containing copolymer rubber A or copolymer rubber B is in an active state, or water, methanol, The respective polymerization solutions may be mixed after the catalyst is deactivated or removed by adding a deactivating agent such as ethanol or other polar solvent. When preparing a rubber solution using this method, the ratio of mixing the polymerization solution containing copolymer rubber A and the polymerization solution of copolymer rubber B in each polymerization solution is determined so as to match the composition of copolymer rubber C and the Mooney viscosity. Since it is extremely easy to know the concentration of the copolymer rubber, the composition of each copolymer rubber, and the Mooney viscosity, they can be easily determined in the same manner as in the first method. As a third method for preparing a rubber solution, a polymer solution containing either copolymer rubber A or copolymer rubber B is first prepared by the method for producing ethylene-α-olefin-diolefin copolymer rubber using the Ziegler catalyst described above. A method of preparing a rubber solution containing copolymer rubber A and copolymer rubber B in a predetermined ratio by producing the other copolymer rubber by subsequently changing the polymerization conditions. In this case, a rubber solution can be prepared by polymerizing copolymer rubber A and copolymer rubber B in the same reactor, or the two reactors can be arranged in series and one of the After preparing a polymerization solution containing copolymer rubber A or copolymer rubber B in a reactor, the polymerization solution is introduced into the other reactor and polymerization is carried out to produce the other copolymer rubber. A rubber solution can also be prepared. In this case, since the polymerization conditions that determine the composition, Mooney viscosity, and concentration of copolymer rubber A or copolymer rubber B in the polymerization solution can be easily known in advance, the rubber solution for obtaining copolymer rubber C can be easily known in advance. It is easy to prepare. Among these methods of preparing rubber solutions, the second method and the third method are preferred. The total amount of copolymer rubber A and copolymer rubber B present in the rubber solution is preferably 20 to 100 g per solution. In the present invention, copolymer rubber C is obtained by removing a catalyst and the like from a rubber solution containing copolymer rubber A and copolymer rubber B, if necessary, and then removing the solvent. A conventional known method can be used to remove the solvent. For example, acetone, methanol,
Examples include a method of adding a precipitating agent such as ethanol to precipitate the copolymer rubber C, followed by solid-liquid separation, and a method of steam distillation. After removing the solvent by such a method, the copolymer rubber C is dried by a known method such as vacuum drying or hot air drying.
can be obtained. In order to produce a foam using the copolymer rubber C as described above, a commonly used method can be employed. That is, compound A is prepared by mixing copolymer rubber C, a softener, a filler, etc. using a mixer such as a Banbury mixer, and then a blowing agent, a vulcanizing agent, etc. are added to compound A using rolls such as an oven roll. Mix to prepare Compound B. This compound B is molded using an extruder or the like, and then heated in a vulcanization tank using a mold, or by free expansion using hot air, a fluidized bed, a molten salt bath, microwaves, or other means. Alternatively, Compound B is directly molded and heated by hot press to complete vulcanization and foaming, and a product as a foam is manufactured. The GS of compound A is 10% due to processing requirements such as biting into the roll and wrapping around the roll.
The types and amounts of copolymer rubber C and compounding agents are adjusted so that the amount is Kg/cm ² or more, preferably 10 to 40 Kg/cm ² . In addition, when vulcanizing and foaming is performed by free expansion, in order to prevent the shape from deforming, compound B is added.
The types and amounts of copolymer rubber C and compounding agents are adjusted so that the GS is 10 Kg/cm ² or more, preferably 10 to 40 Kg/cm ² . In the process of the invention, the proportion of copolymer rubber C in the foaming compound (compound B) is from 20 to 65% by weight, preferably from 25 to 55% by weight. As the softener, softeners normally used for rubber are used, such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petroleum softeners such as vaseline; coal tar, coal tar pitch, etc. Coal tar-based softeners; fatty oil-based softeners such as castor oil, linseed oil, rapeseed oil, and coconut oil; tall oil; sub-waxes such as beeswax, carnauba wax, and lanolin; ricinoleic acid, palmitic acid, and barium stearate , aliphatic acids and fatty acid salts such as calcium stearate and zinc laurate; synthetic polymeric substances such as petroleum resins, atactic polypropylene, and coumaron indene resins. Among these, petroleum-based softeners are preferably used, and process oils are particularly preferred. These softeners are used in an amount of 10 parts by weight or more, preferably 30 to 150 parts by weight, per 100 parts by weight of the copolymer rubber C. If too large amounts are used, the GS of Compound A and Compound B will decrease, leading to poor winding on rolls, loss of shape during vulcanization and foaming with free expansion, and decreased strength of the foam. Quality requirements will no longer be met. If the amount is less than 10 parts by weight, the fluidity of Compound A will decrease and it will be difficult to bite into the roll. As a vulcanizing agent, sulfur; sulfur compounds such as sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate; magnesium oxide, zinc white,
Metal compounds such as red lead; dicumyl peroxide,
2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-
Di(benzoylperoxy)hexane, 2,5-
Dimethyl-2,5-di(tert-butylperoxy)
Organic peroxides such as hexene-3, di-tert-butyl peroxide, di-tert-butyl peroxy-3,3,5-trimethylcyclohexane, and tert-butyl hydroperoxide can be mentioned. Among them, sulfur and organic peroxides are preferably used, especially sulfur, dicumyl peroxide, ditert-butyl peroxide, ditert-butyl peroxide-3, 3, and 5.
-Trimethylcyclohexane is preferred. Sulfur is usually per 100 parts by weight of copolymer rubber C.
It is used in a proportion of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight. The organic peroxide is usually used in an amount of 0.1 to 15 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the copolymer rubber C. Further, a vulcanization accelerator is used in combination with a vulcanizing agent, if necessary. As a vulcanization accelerator, 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・
Thiazoles such as 6-diethyl-4-morpholinothio)benzothiazole and dibenzothiazyl hyphon disulfide; diphenylguanidine, triphenylguanidine, diorthotolylguanidine, orthotolyl biguanide, diphenylguanidine phthalate, etc. Guanidine series;
Aldehyde amines or aldehyde-ammonia systems such as acetaldehyde-aniline reactants, butyraldehyde-aniline condensates, hexamethylenetetramine, acetaldehyde ammonia; 2
- Imidazolines such as mercaptoimidazoline; thioureas such as thiocarbanilide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide Thiuram series such as Rufid, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide; zinc dimethyldithiocarbamate, zinc diethylthiocarbamate, zinc di-n-butyldithiocarbamate, zinc ethylphenyldithiocarbamate, butyl Zinc phenyldithiocarbamate, sodium dimethyldithiocarbamate, selenium dimethyldithiocarbamate,
Examples include dithioate salts such as tellurium diethyldithiocarbamate; xanthate salts such as zinc dibutylxanthate. These vulcanization accelerators are used in an amount of 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the copolymer rubber C. In addition, when crosslinking with peroxide, sulfur, P
- Quinone dioxime series such as quinone dioxime;
Crosslinking aids such as methacrylate type such as polyethylene glycol dimethacrylate; allyl type such as diallyl phthalate and triallyl cyanurate; other maleimide type; and divinylbenzene may be used. Fillers include SRF, GPF, FET, HAT,
Carbon black commonly used in rubber such as ISAF, SAF, FT, and MT; inorganic fillers such as finely divided silicic acid, calcium carbonate, talc, and clay are preferably used. As blowing agents, inorganic blowing agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite;
Nitroso compounds such as N'-dimethyl N, N'-dinitroso terephthalamide, N, N'-dinitroso pentamethylene, tetramine; azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene, barium・Azo compounds such as azodicarboxylate; benzene sulfonyl hydrazide,
Toluene sulfonyl hydrazide, P.P'-oxybis(benzenesulfonyl hydrazide),
Sulfonyl hydrazide compounds such as diphenylsulfone-3,3'-disulfonyl hydrazide;
Examples include azide compounds such as calcium azide, 4,4'-diphenyl disulfonyl azide, para-toluene malhonyl azide, and the like. The blowing agent is blended in an amount of 0.5 to 30 parts by weight, preferably 1 to 15 parts by weight, per 100 parts by weight of the rubber component. Further, a foaming aid may be used in combination with a foaming agent if necessary. A foaming aid is an additive that functions to lower the decomposition temperature of a foaming agent, promote decomposition, and make cells uniform. Examples of foaming aids include organic acids such as salicylic acid, phthalic acid, stearic acid, and oxalic acid; urea and its derivatives. Antiaging agents, thickeners, and other additives may also be used in the formulation of the present invention. Further, other types of rubber may be mixed together with the copolymer rubber C of the present invention as a rubber component of the foam. According to the method of the present invention described in detail above, problems in producing foam from ethylene-α-olefin-diolefin copolymer rubber, using a softener if necessary, can be solved, especially when vulcanization is achieved by free expansion.・The problem of deformation of the foam shape due to deformation during foaming is solved, and it also prevents the foam from biting into the roll.
Processing problems such as wrapping around rolls have also been resolved.
It is possible to provide an inexpensive and high-performance sealing material. In particular, the method of the present invention is excellent as a method for producing foams by free expansion. Therefore, the present invention has great industrial value. This will be explained in detail below using Examples. Preparation of copolymer rubber Using vanadium oxytrichloride and ethylaluminum sesquichloride as polymerization catalysts and hexane as a polymerization solvent, ethylene, propylene, ethylidene norbornene, and a molecular weight regulator were fed into a polymerization vessel, and the mixture shown in Table 1 was prepared. A polymerization solution containing copolymer rubber A (A ₁ to _{A 6} ) and a polymerization solution containing copolymer rubber B (B ₁ to _{B 7} ) were obtained.
The concentration of each polymerization solution was adjusted to 30 g/ml by appropriately adding hexane after the polymerization was completed.
Table 1 shows the TS (maximum tensile stress: Kg/cm ² ) and EB (elongation at break: %) of each copolymer rubber. The TS and EB of each copolymer rubber in the present invention were measured as follows. Based on the tensile test method of JIS K 6301 using the 1 mm thick test piece shown in Figure 2 of the attached drawings,
Measurement is carried out at a temperature of 25°C and a tensile speed of 500 mm/min, and the maximum tensile stress until breakage is defined as the maximum tensile strength TS. In addition, the elongation at break EB is calculated by dividing the distance at the break point between the two marked lines, which are the line connecting 9 and 11 and the line connecting 10 and 12 of the test piece, by the distance between the two marked lines before tensioning. Then, multiply this value by 100. The test piece used here was made by placing approximately 10 g of raw rubber containing no compounding agents into a heat press at 160°C, leaving it at a pressure of 50 kg/ ^cm2 for 10 minutes, and then immediately immersing it in a large amount of water at 20°C. Leave it for 10 minutes, then remove it from the water.
Thickness 1.0 obtained after being left in an atmosphere at 25℃ for 1 hour
The dumbbell-shaped specimen shown in FIG. 2 was punched out from a sheet of 2.0 mm in diameter. This dumbbell-shaped test piece is 1 and 4 in Figure 2.
(5 and 8) 50mm, 1 and 5 (4 and 8) 12mm, 9 and 10 (11 and 12) 10mm, 9 and 11 (10 and 12) is 4mm
and 2 and 9 (3 and 10, 6 and 11, 7 and 1
The curve connecting 2) is a circular arc with a radius of 6 mm.

[Table] Example 1 Polymerization solution 12 containing copolymer rubber A ₁ prepared by the above method and polymerization solution containing copolymer rubber B ₁
28 into a tank equipped with 50 stirring blades.
After mixing for 30 minutes, hexane was removed by steam distillation, water and copolymer rubber C were separated, and the copolymer rubber was heated at 120°C under reduced pressure under a stream of nitrogen gas for 4 hours.
66 mol% ethylene units, by drying for hours
Iodine number 25, Mooney viscosity (ML ₁₊₄ , 121℃)
83, 1200 g of copolymer rubber C in which copolymer rubber A ₁ and copolymer rubber B ₁ were present in a weight ratio of 30/70 was obtained. Using 1100 g of this copolymer rubber C, a 4.3 Banbury mixer (OOC type,
Copolymer rubber C, process oil, zinc white, stearic acid and SRF
After compound A was prepared by kneading carbon black for 6 minutes, it was divided into two parts and left in an atmosphere of 30°C and 5°C for 1 day. Each Compound A, sulfur, vulcanization accelerator, and blowing agent were mixed in the proportions shown in Table 2 using an 8 x 20 inch open roll at a roll temperature of 40°C for 15 minutes.
Compound B was prepared by kneading for a minute.

【table】

[Table] At this time, the manner in which Compound A was bitten into the roll and the manner in which it was wound was observed, and the results are shown in Table 3. Next, Compound B was prepared at 60 °C with the die and barrel temperature controlled at 60 °C and the screw temperature at 40 °C.
Moldings were prepared in a mmφ extruder and then continuously introduced into a hot air bath controlled at 220°C and heated for 5 minutes to cause vulcanization and foaming, with cross-sections as shown in the accompanying drawings, Figure 1. A foam with a shape of In this tubular part, the wall thicknesses 1 and 2, 3 and 6 are 2 mm, the inner diameters 2 and 3, 4 and 5 are 16 mm unless the shape is deformed, and the interval between 7 and 8 is 20 mm. The apparent specific gravity of the foam was measured in accordance with the method specified in the Physical Test Methods for Expanded Rubber by the Japan Rubber Institute Standards (SRIS). Also, from the obtained foam
A dumbbell-shaped test piece was punched out and tensile speed was 500mm/min at 25℃ according to the method specified in JIS K6301.
The maximum tensile stress measured up to the point of breakage was determined and used as the tensile strength. Also, in Figure 1, foam 4 and 5
Measure the distance D between 2 and 3 and the distance H between 2 and 3 (D/
H)×100 (%) was defined as the shape retention rate, which was used as a guideline for shape loss. The above results are shown in Table 3. Comparative Examples 1 to 4 Except for mixing the polymer solution containing copolymer rubber A ₁ and the polymer solution containing copolymer rubber B ₁ in Example 1 so that the weight ratio of each copolymer rubber is as shown in Table 3. Table 3 shows the results obtained by performing the same operations as in Example 1. Comparative Example 5 330 _g of copolymer rubber A ₁ obtained in Example 1 by removing hexane and drying the polymer solution containing copolymer rubber A 1 and the polymer solution containing copolymer rubber B ₁ separately without mixing them. , Copolymer rubber B ₁ 770g was prepared in Example 1.
When the same operation as in the example was performed except that copolymer rubber C was used instead of copolymer rubber C, there was no variation in the measured values of the GS of compounds A and B, as well as the specific gravity, tensile strength, and shape retention of the sponge rubber. It was intense. The range of the variation is shown in Table 3.

[Table] Examples 2 to 8, Comparative Examples 6 to 9 In Example 1, each polymerization solution in Table 1 was adjusted to have the proportions of copolymer rubber A and copolymer rubber B listed in Tables 4 and 5. The same operations as in Example 1 were performed except for the use. The results are shown in Table 4.

【table】

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of foams manufactured in Examples and Comparative Examples, and FIG. 2 is a cross-sectional view of foams manufactured in Examples and Comparative Examples.
FIG. 2 is a plan view of a test piece used for measuring TS and EB.

Claims (1)

[Claims] 1 Ethylene-α-olefin-diolefin copolymer rubber A having an ethylene unit content of 73 mol% or more and ethylene-α-olefin-diolefin copolymer rubber B having an ethylene unit content of 73 mol% or less
Mixed in a solution state at a weight ratio of 75/25 to 5/95, the average composition of the mixture is 55 to 73 mol% of ethylene units, and the Mooney viscosity (ML ₁₊₄ , 121°C) is 65 to 120. A method for producing a foam, characterized in that copolymer rubber C adjusted to have the following properties is used as a rubber component of a foam material.