JPH0443935B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a composition for sponge rubber containing as an essential component an ethylene-α-olefin-diolefin copolymer rubber that has excellent processability, sealability, and low-temperature properties. BACKGROUND OF THE INVENTION Most of the demand for sponge rubber is for automobile applications, specifically around doors and trunks, and for sealing against water, sound, etc. Conventionally, natural rubber, chloroprene rubber, styrene-butadiene copolymer rubber, etc. have been used as the base material for such sponge rubber, but ethylene-α has superior weather resistance, heat resistance, and light weight.
-Olefin-diolefin copolymer rubber (hereinafter sometimes simply referred to as "EPDM") has attracted attention,
Currently, it is being almost completely replaced by EPDM. Problems to be Solved by the Invention However, as the requirements for automobiles have become more sophisticated, the requirements for the sponge rubber used in them have also become more sophisticated, and it has become difficult to provide sufficiently satisfactory sponge rubber using conventional technology. It's coming. In particular, as expressway networks have been developed not only in Europe and the United States, but also in Japan, and opportunities for automobiles to travel at high speeds for long periods of time have increased, demand for lightweight sponge rubber with excellent sealing properties against noise and water has already increased. It can even be said to be a social need. Further, the characteristics of the sponge rubber must be maintained under various temperature conditions from low to high temperatures, and the sponge rubber must also be soft so that the door can be opened and closed smoothly. On the other hand, various requirements must be met in the process of manufacturing such sponge rubber. That is, it is required to have excellent processability in a Banbury mixer, roll mill, extruder, etc., to not lose its shape during vulcanization, and to have low manufacturing costs. Conventionally, for example, in Japanese Patent Publication No. 58-57450, the ethylene content is 55 to 73 mol%, the product of the maximum tensile stress and elongation at break of the copolymer rubber is 7 × 10 ³ or more,
It has been shown that EPDM with Mooney viscosity (ML ₁₊₄ , 121℃) of 65 to 120 has excellent processability and shape deformability, but even when using this copolymer rubber, the processability and cold resistance are ~ It is not possible to obtain a sponge rubber with sufficient balance in sealing performance, especially in terms of cold resistance. Sponge rubbers made of ethylene-α-olefin-ethylidenenorbornene-dicyclopentadiene quaternary copolymers with excellent foaming properties and processability have also been proposed, but they generally have a wide molecular weight distribution and therefore have poor low-temperature properties. However, there is no sponge material that is completely satisfactory in terms of strength. The present invention was made against the background of the above-mentioned conventional technical problems, and uses ethylene-α-olefin-diolefin copolymer rubber, which has excellent processability during manufacturing, is lightweight, and has excellent sealing performance and door opening/closing properties. Another object of the present invention is to provide a composition capable of obtaining a sponge rubber having excellent sponge properties and less temperature dependence. Means for Solving the Problems The present invention provides an ethylene-α-olefin-diolefin copolymer rubber that satisfies the following conditions (a) to (e).
The present invention provides a sponge rubber composition comprising 0.5 to 20 parts by weight of a blowing agent per 100 parts by weight. (a) The number of carbon atoms in α-olefin is 3 to 12, and the weight ratio of ethylene/α-olefin is 70 to 40/30.
60. (b) The diolefin consists of ethylidene norbornene and dicyclopentadiene, the amount of unsaturation in the copolymer rubber is 15 to 45 in terms of iodine value, and the iodine value ratio of ethylidene norbornene to dicyclopentadiene is 1:1 to 6: 1. (c) Mooney viscosity of copolymer rubber (ML ₁₊₈ , 120℃)
But 55-110. (d) When the copolymer rubber is dissolved in cyclohexane at 30°C, the amount of insoluble matter is 3 to 15% by weight. (e) The ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw/Mn) is 2 to 10. Ethylene-α-olefin-diolefin copolymer rubber (hereinafter sometimes simply referred to as "copolymer rubber") serving as the base material of the sponge rubber composition of the present invention
must satisfy the conditions (a) to (e) above. (a) The α-olefin used as a monomer for copolymerization of the copolymer rubber is an α-olefin having 3 to 12 carbon atoms, and specific examples include propylene, butene-1, 4-methylpentene-1, and hexene-1.
1, octene-1, etc. Preferred is propylene. These α-olefins are 1
It can be used either as a species or as a combination of two or more. In addition, the weight ratio of ethylene/α-olefin in the copolymer rubber is 70 to 40/30 to 60, preferably
65-45/35-55. That is, the ethylene content in the copolymer rubber is 70% by weight.
If it exceeds the above range, wasteful energy is required during kneading due to deterioration of fluidity, processability problems such as worsening of the raw rubber being bitten by the rolls and extruder occur, and furthermore, the cold resistance of the sponge rubber decreases. invite On the other hand, if the ethylene content is less than 40% by weight, the filler will not be sufficiently dispersed and the surface of the sponge rubber will become rough, resulting in a decrease in sealing properties and the strength of the sponge rubber falling below a practical range. (b) As the diolefin component of the copolymer rubber of the present invention, it is necessary to use ethylidenenorbornene (hereinafter sometimes simply referred to as "ENB") and dicyclopentadiene (hereinafter simply referred to as "DCPD") in combination. There is. In either case of using ENB alone or DCPD alone as the diolefin, the balance between vulcanization and foaming is disrupted, making it impossible to obtain a highly foamed and soft sponge rubber. The copolymer rubber used in the present invention is
By combining ENB and DCPD to form a quaternary EPDM, the cold resistance becomes excellent, probably because the ethylene sequence distribution is different from that of a single system. Furthermore, in the blend system of ENB-based EPDM and DCPD-based EPDM, quality control during the manufacturing process is complicated, and ENB and DCPD-based EPDM are present in the same polymer chain.
Perhaps because the vulcanization and foaming conditions are different compared to quaternary EPDM containing DCPD, problems arise with the surface texture and feel of the sponge rubber. The amount of unsaturation of the diolefin in the copolymer rubber is 15 to 45 in terms of iodine value, preferably 20 to 40, and the iodine value ratio of ENB and DCPD is 1:1 to 1.
The ratio is 6:1, preferably 2:1 to 5:1. If the total amount of unsaturation is less than 15 in terms of iodine number, the obtained sponge rubber will not be highly foamed, and the rubber will not have sufficient mechanical strength and cold resistance. On the other hand, when the iodine value exceeds 45, high foaming cannot be achieved and the desired sponge rubber cannot be obtained. Furthermore, if the iodine value ratio of ENB to DCPD is less than 1:1 or greater than 6:1, the balance between vulcanization and foaming will be disrupted, and the desired sponge rubber will not be obtained. (c) Mooney viscosity of copolymer rubber (ML ₁₊₈ , 120℃)
is 55-110, preferably 70-95. If the Mooney viscosity is less than 55, the sponge strength will be insufficient, while if it exceeds 110, the kneading properties will deteriorate. (d) When the copolymer rubber is dissolved in cyclohexane at 30°C, the amount of undissolved matter must be 3 to 15% by weight. If the cyclohexane insoluble content is less than 3% by weight, it will lead to deterioration of kneading properties, roll workability, and extrusion surface texture, while if it exceeds 15% by weight, the cold resistance of the resulting sponge rubber will deteriorate. A problem arises. These phenomena occur because the cyclohexane insoluble amount is mainly composed of crystalline components based on long chain length components of ethylene. (e) The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw/Mn) of the copolymer rubber determined from gel permeation chromatography (GPC) measured at 120°C in orthodichlorobenzene is , 2-10, preferably 3.5-8.5
It is necessary that When Mw/Mn is less than 2, processing problems such as kneading properties in a Banbury mixer and rollability in a roll mill occur. On the other hand, when Mw/Mn is greater than 10, there are no problems in processing, but the setting properties and strength of the sponge rubber deteriorate mainly due to the influence of low molecular weight components. The composition for sponge rubber of the present invention has the above-mentioned (a)
The copolymer rubber that satisfies the conditions of ~(e) is an essential component, and the composition contains various additives and other rubbers, etc., and the content of the copolymer rubber is at least 20% by weight, preferably at least 20% by weight in the composition. is 20-60% by weight. If the copolymer rubber is less than 20% by weight based on the composition, the resulting sponge rubber will no longer have the properties aimed at by the present invention. The copolymer rubber that satisfies the conditions (a) to (e) above includes at least one organometallic compound selected from groups - - of the periodic table and at least one selected from groups - - and groups of the periodic table. It is produced using a catalyst in combination with one or more transition metal compounds. As such an organometallic compound, an organoaluminum compound is suitable, and specifically, triethylaluminum, triisobutylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, sesquiethylaluminum chloride, ethylaluminum dichloride, isobutylaluminum dichloride, n-
At least one kind may be selected from octylaluminum dichloride and the like, and preferably a mixture of trialkylaluminum and sesquialkylaluminium. Further, as the transition metal compound, vanadium compounds and titanium compounds are suitable, and specifically vanadium oxytrichloride, alkoxyvanadate, mixtures of vanadium oxytrichloride and saturated aliphatic alcohols having 1 to 12 carbon atoms, It is sufficient _to select at _least one titanium compound represented by , preferably a mixture of a vanadium compound and a titanium compound. Ethylene, α-olefin, ethylidene norbornene, and dicyclopentadiene are brought into contact with each other using the catalyst described above, using n-hexane as a polymerization solvent, at a polymerization temperature of -10 to 50°C and a pressure of 0 to 10 kg/cm ² . Molecular weight can be adjusted using hydrogen gas. If the Mooney viscosity is high, it can also be finished as an oil-extended rubber. The ethylene-α-olefin-diolefin copolymer rubber used in the present invention is prepared by adding fillers, softeners, blowing agents, crosslinking agents, etc. as necessary to form a composition for sponge rubber, and then processed by a commonly used method. Therefore, foaming and crosslinking are performed to produce sponge rubber. Fillers that can be mixed include inorganic fillers such as carbon black, particulate silicic acid, calcium carbonate, magnesium carbonate, clay, and talc, and organic fillers such as fiber flock, but inorganic fillers are generally preferred. used. The amount of filler added is often in the range of 50 to 200 parts by weight per 100 parts by weight of the copolymer rubber. Examples of the softening agent include so-called process oils such as aromatic oil, naphthenic oil, and paraffin oil, which are commonly used in rubber, and vegetable oils such as coconut oil. Process oils are preferred, and paraffin oil is particularly preferred. The amount of the softener added is 30 parts by weight or more based on 100 parts by weight of the copolymer rubber. As blowing agents, inorganic blowing agents such as ammonium carbonate, sodium bicarbonate, anhydrous sodium nitrate, dinitropentamethylenetetramine, N,
N'dimethyl-N,N' dinitrosoterephthalamide, benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, p,p'-oxybis(benzenesulfonylhydrazide), 3,3'-disulfonehydrazide diphenylsulfone, azobisiso Organic blowing agents include butyronitrile and azobisformamide. Further, a urea-based, organic acid-based, or metal salt-based foaming aid can be used together with the foaming agent. The foaming aid is used together with a foaming agent having a high decomposition temperature, such as dinitropentamethylenetetramine or azodicarbonamide, and is added for the purpose of appropriately lowering and adjusting the foaming temperature. As a specific example,
Examples include Selton N (manufactured by Sankyo Kasei Co., Ltd.) and Selpere M ₃ (manufactured by Eiwa Kasei Co., Ltd.). The amount of foaming agent and foaming aid added is based on the copolymer rubber.
For 100 parts by weight, the blowing agent is in the range of 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, and the blowing aid is in the range of 0 to 20 parts by weight. As a crosslinking agent, sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur, sulfur chloride, selenium, tellurium, thiuram disulfides,
Dithiodimorpholine, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, di-tert-butyl peroxide, dicumyl peroxide tert-butylcumyl peroxide, 2,5-dimethyl-
Peroxides such as 2,5-di(tert-butylperoxy)hexane, 1,3-bis-(tert-butylperoxy-isopropyl)benzene, preferably sulfur, peroxides, especially sulfur , 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, di-tert-butyl peroxide, and dicumyl peroxide. When sulfur is used as a crosslinking agent, aldehyde ammonias such as hexamethylenetetramine, guanidines such as diphenylguanidine, di-ortho-tolylguanidine, ortho-tolyl-biguanidine, di-ortho-tolylguanidine, dicaracol boron salt, Thiocarbanilide, di-ortho-
tolylthiourea, N,N'-diethylthiourea,
Thioureas such as tetramethylthiourea, 2-mercaptoimidazoline, trimethylthiourea, mercaptobenzothiazole, N-tertiarybutyl-2-benzothiazole phenamide, N,
N'-dicyclohexyl-2-benzothiazoylsulfenamide, dibenzothiazyl disulfide, 2-(4-morpholinodithio)benzothiazole, 2-(2,4-dinitrophenyl)-mercaptobenzothiazole, N,N '-Diethylthiocarbamoyl-2-benzothiazoyl sulfide, N,N'-diisopropyl-2-benzothiazole sulfenamide, N-cyclohexyl-2
- Thiazoles such as benzothiadylsulfenamide, N-oxydiethylene-2-benzothiazolesulfenamide, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, di-
Dithiocarbamates such as zinc n-butyldithiocarbamate, zinc ethylphenyldithiocarbamate, lead ethylphenyldithiocarbamate, sodium dimethyldithiocarbamate, copper dimethyldithiocarbamate, selenium diethyldithiocarbamate, tellurium diethyldithiocarbamate, piperazine- Xanthates such as bis-(0,0'-distearyldithiophosphate), tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, dipenta One type or a combination of two or more types of thiurams such as methylenethiuram tetrasulfide can be used as the crosslinking accelerator. In addition, in crosslinking with peroxides, sulfur, p-quinonedioxime, p,p'-dibenzoylquinonedioxime, lauryl methacrylate, ethylene glycol acrylate, trimethylolpropene trimethacrylate, diaryl phthalate,
Crosslinking aids such as triallyl cyanurate can also be added. Other crosslinking accelerators, such as zinc white, magnesium oxide, litharge, red lead, white lead,
stearic acid, oleic acid, zinc stearate,
Organic amines such as Acting (manufactured by Yoshitomi Pharmaceutical Co., Ltd.), organic acids such as phthalic anhydride, and nitroso compounds such as N,N'-nitrosodiphenylamine can be added. The amount of crosslinking agent added is ethylene-α-olefin-diolefin copolymer rubber.
It is used in an amount of 0.5 to 10 parts by weight per 100 parts by weight. Further, the crosslinking accelerator is used in an amount of 0.1 to 10 parts by weight. Furthermore, anti-aging agents and other additives commonly used in rubber may be added in arbitrary proportions. Also other types of rubbers such as butyl rubber, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, and Mooney viscosity,
It can also be used in combination with ethylene-α-olefin copolymer rubbers having different copolymer compositions and molecular weight distributions. In the production of sponge rubber in the present invention,
The blending ratio, blending method, and order of blending of other rubbers, fillers, softeners, blowing agents, and crosslinking agents to be blended with the copolymer rubber are not particularly limited, but the copolymer rubber, etc. may be mixed using a Banbury mixer, etc. After mixing the rubber, filler, softener, etc., foaming agents, foaming aids, crosslinking agents, etc. are added using a roll or the like. Next, foaming and crosslinking are carried out by placing the material in a mold and increasing the temperature using the method used for normal sponge rubber production. Alternatively, sponge rubber can be produced by molding into an arbitrary shape using an extrusion molding machine and foaming and crosslinking by heating in a crosslinking tank. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the Examples unless it exceeds the scope of the claims. In the examples, various analysis methods and physical property measurement methods were conducted in accordance with the following methods. () Propylene content Measured by infrared absorption spectrum () Iodine number Measured by infrared absorption spectrum () Mooney viscosity (ML ₁₊₈ , 120℃) Preheated for 1 minute, measured for 8 minutes, measured at 120℃ () Cyclohexane insoluble amount Cut 250 mg of raw rubber without compounding agents into pieces with a side length of 1 mm or less, soak it in 100 ml of cyclohexane, and leave it in a constant temperature bath at 30°C for 48 hours. Thereafter, it is filtered through an 80-mesh stainless steel wire mesh, and the insoluble matter is vacuum dried at 105°C for 1 hour and then weighed. The value obtained by dividing this insoluble amount by the weight of the raw rubber is defined as the cyclohexane insoluble amount (wt%). In the case of oil-extended rubber, it is corrected to the weight % based on the rubber component excluding oil. () The processability of the compounded rubber in a Banbury mixer was evaluated by visually evaluating the state of the composition after being discharged from the Banbury in terms of filler mixing state, skin gloss, and cohesion. The results were shown as excellent, good, fair, poor, or poor. () The roll processability of compounded rubber is determined by rolling the unvulcanized compound with a 10-inch roll at a roll temperature of 50℃±
It was wound around a roll at 5° C. with a nip width of 2 mm, and evaluated based on the length of time required to tightly wrap it and whether or not it was wound tightly. The results are excellent, good, fair,
Indicated as poor or poor. () After the roll processability test, the surface condition of the sheet sample was evaluated based on the smoothness, gloss, etc. of the surface surface. Result is,
Indicated as excellent, good, fair, poor, or poor. () Sponge properties The samples used to measure the following sponge properties were the sponge rubbers shown in Examples. Specific gravity Measured according to the Japan Rubber Association standards and physical test method for expanded rubber. Skin, feel The skin was evaluated based on the smoothness, gloss, and non-stickiness of the sponge rubber surface. The feel was evaluated based on the elasticity and softness when the sponge rubber was bent. All results were shown as excellent, good, fair, poor, or poor. Tensile strength (TB) A No. 3 dumbbell-shaped specimen was punched out from sponge rubber and measured according to JIS K6301. Compression set: 50% in the direction of Figure 1 a-b according to JIS K6301
The compression set was measured at -20°C for 22 hours and at +70°C for 22 hours. () Mw/Mn Measured as follows according to Takeuchi, Gel Permeation Chromatograph, published by Maruzen Co., Ltd. Using standard polystyrene with a known molecular weight (manufactured by Toyo Soda Co., Ltd., monodisperse polystyrene),
Molecular weight M and its GPC (Gel Permeation)
Chromatograph) count and draw a correlation diagram calibration curve between molecular weight M and EV (Elution Volume). The concentration at this time is 0.02% by weight. The standard polystyrene calibration curve is corrected to the EPDM calibration curve using the universal method. Using the GPC measurement method, a GPC pattern of the sample is taken, and M is determined from the above. The sample preparation conditions and GPC measurement conditions at that time are as follows. Sample preparation (a) Antioxidant 2,6 in o-diclobenzene solvent
-Add and dissolve 0.08% by weight of di-tert-butyl-p-cresol. (b) Transfer the sample to an Erlenmeyer flask together with o-dichlorobenzene solvent to a concentration of 0.1% by weight. (c) Heat the Erlenmeyer flask to 120°C and stir for about 60 minutes to dissolve. (d) Subject the solution to GPC. In addition, it is automatically filtered with a 0.5μ sintered filter within the GPC device. GPC measurement conditions (a) Equipment 150C type manufactured by Waters (b) Column H type manufactured by Toyo Soda Co., Ltd. (c) Sample amount 500μ (d) Temperature 120℃ (e) Flow rate 1ml/min (f) Total number of theoretical plates of column 1×10 ⁴ to 2×10 ⁴ (measured value using acetone) Examples 1 to 4, Comparative Examples 1 to 9 Rubber compounds were made using the copolymer rubber shown in Table 1 and the formulation shown in Table 2. It was created. The preparation method is to mix the ingredients in Table 2 using a BR type Banbury mixer with a rotor rotation speed of 60 rpm.
The mixture was kneaded for 5 minutes at a temperature of 50°C, and then the components [ ] in Table 2 were kneaded for 5 minutes using a 10-inch roll maintained at 50°C. The roll rotation speed is 22/22 for the front and rear rolls.
It was hot at 28 rpm. The obtained rubber compound was formed into a molded product using a 50Φmm extruder (die temperature: 80°C), and passed through a hot air bath at 200°C for 5 minutes to obtain a sponge rubber. The nozzle attached to the extruder is shown in FIG. In addition, the characteristics of the obtained sponge rubber were
Shown in the table.

【table】

【table】

【table】

[Table] Effects of the Invention The composition for sponge rubber of the present invention provides a sponge rubber that has excellent processability during production, is lightweight, has excellent sealing properties and door opening/closing properties, and has less temperature dependence of sponge properties. , and its industrial significance is extremely large.

[Brief explanation of drawings]

FIG. 1 shows the shape of a mouthpiece to be attached to an extruder used for molding unvulcanized rubber.

Claims (1)

[Claims] 1. Ethylene-α- that satisfies the following conditions (a) to (e):
A sponge rubber composition comprising 0.5 to 20 parts by weight of a blowing agent to 100 parts by weight of olefin-diolefin copolymer rubber. (a) The number of carbon atoms in α-olefin is 3 to 12, and the weight ratio of ethylene/α-olefin is 70 to 40/30.
60. (b) The diolefin consists of ethylidene norbornene and dicyclopentadiene, the amount of unsaturation in the copolymer rubber is 15 to 45 in terms of iodine value, and the iodine value ratio of ethylidene norbornene to dicyclopentadiene is 1:1 to 6: 1. (c) Mooney viscosity of copolymer rubber (ML ₁₊₈ , 120℃)
But 55-110. (d) When the copolymer rubber is dissolved in cyclohexane at 30°C, the amount of insoluble matter is 3 to 15% by weight. (E) The ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw/Mn) is 2 to 10.