JPH0262582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sponge. For more details,
This invention relates to a sponge manufactured by vulcanizing and foaming ethylene/α-olefin/polyene copolymer rubber. Sponges manufactured by vulcanizing and foaming ethylene/α-olefin/polyene copolymer rubber such as ethylene/propylene/polyene copolymer rubber generally have excellent weather resistance, ozone resistance, and heat aging resistance. Because of these properties, it has come to be widely used as sealing materials for automobiles, sealing materials for civil engineering and construction, etc. The copolymer rubber used to manufacture such sponges must have good roll processability and extrusion moldability, high vulcanization speed, excellent strength of the product sponge rubber, and smooth surface texture of the sponge. is desired. However, none of the commercially available copolymer rubbers has all of these desired properties. For example, ethylene, a typical copolymer rubber,
Although propylene/5-ethylidene-2-norbornene copolymer rubber has the advantages of high vulcanization speed and high strength of sponge rubber, it has poor roll processability and extrusion processability.
It is difficult to obtain a sponge with high smoothness after vulcanization and foaming. Ethylene-propylene-dicyclopentadiene copolymer rubber, which is another typical copolymer rubber, has the advantage of excellent roll processability and extrusion processability, but has a low vulcanization rate and is difficult to cure and foam. In this case, foaming precedes
The disadvantage is that the sponge surface has low smoothness. Attempts to simultaneously copolymerize two or more types of polyene components have been made for a relatively early period of time in order to improve the various properties of such copolymerized rubbers. has not been reached yet. For example, even when 5-ethylidene-2-norbornene and dicyclopentadiene are used together as polyenes (Japanese Patent Publication No. 7713/1983), extrusion processability, vulcanization speed, and vulcanization physical properties are well balanced. Therefore, depending on the content ratio of each of these polyene components, any of the above properties does not exhibit values that are fully satisfied. In view of the current situation, the present inventors conducted various studies in order to obtain a material that has excellent extrusion moldability and vulcanizability, and also has excellent rubber strength and surface smoothness when molded into a sponge. It has been found that it is extremely effective to use a specific new copolymer rubber as described above. Therefore, the present invention relates to a sponge, the sponge is composed of ethylene/α-olefin and polyene, (a) the copolymerization molar ratio of ethylene and α-olefin is from 55/45 to 95/5, and ( b) The polyene is 5-ethylidene-2-norbornene (ENB) and 5-vinyl-2-norbornene (VNB), and the copolymerization molar ratio (ENB/VNB) is 1 to 20, (c ) The amount of copolymerization of these polyene components is 2 to 40 in terms of iodine value, and (d) the intrinsic viscosity [η] is 1.0 to 6.0 dl/g (135°C, in delican) Ethylene, α-olefin, Manufactured by vulcanizing and foaming polyene copolymer rubber. This new copolymer rubber contains ethylene, α-olefin, 5-ethylene-2-norbornene and 5
- It is a random copolymer of vinyl-2-norbornene, and is produced by the method described in JP-A-58-191705. α-olefin generally has 3 to 10 carbon atoms.
α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-
1-pentene, 1-octene, 1-decene, etc.
Preferably propylene or 1-butene is used, preferably at least one of propylene or 1-butene. The copolymerization molar ratio of ethylene and these α-olefins is about 55/45 to 95/5, preferably about 60/40 to
It is within the range of 85/15. If the ethylene content is higher than this, the elastic properties of the sponge will be inferior, while if the ethylene content is lower than this, other physical properties of the sponge, such as mechanical strength, will be inferior. . This copolymerization molar ratio is
Absorbance by infrared spectrophotometer or ^C13 NMR
It can be determined by measuring the intensity with a spectrometer. The copolymerization molar ratio of 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene (hereinafter referred to as polyene copolymerization molar ratio) is within the range of about 1 to 20, preferably about 2 to 10. If the content of 5-ethylidene-2-norbornene is lower than this, the physical properties of the sponge, such as mechanical strength, will be poor, while if the content is higher than this, the physical properties of the sponge, such as roll processability, extrusion processability, etc. will be poor. It becomes like this. The copolymerization molar ratio of these polyene components is
Measurement of intensity with a ^C13 NMR spectrometer,
Alternatively, it can be measured by analyzing the content of unreacted polyene components in the copolymerization reaction solution using a gas chromatograph. These polyene components are copolymerized to have an iodine value of about 2 to 40, preferably about 5 to 30. The intrinsic viscosity [η] of the copolymer rubber used is
Approximately 1.0 to 6.0 dl/g, measured in decalin at 135°C,
Preferably it is within the range of about 1.2 to 4.0 dl/g. If the intrinsic viscosity is smaller than this, the roll processability will be poor and the rubber strength will not be sufficient. If the intrinsic viscosity is larger than this, the extrusion surface will be poor when extruded, for example, and the processability will be poor. Deteriorate. Moreover, this copolymer rubber exhibits a large weight average molecular weight <M> _W (as measured by light scattering method) in comparison to its intrinsic viscosity. Expressing this in another way, the intrinsic viscosity of the copolymer rubber used in the present invention is [η],
The intrinsic viscosity of a linear ethylene/propylene copolymer (ethylene content 70 mol%) with a Q value (weight average molecular weight/number average molecular weight by gas permeation chromatography) of 2.5 is [η] (7.2 × 10 ^-4 <M 〉 Calculated from ^0.67 _W )
When defining [η]/[η]=g* η,
This value is in the range of about 0.2-0.9, preferably about 0.4-0.8. The standard linear ethylene/propylene copolymer described above is produced by copolymerizing ethylene and propylene in n-hexane in the presence of a catalyst consisting of ethylaluminum sesquihalide and vanadium oxychloride. Therefore, it can be easily obtained. As mentioned above, in a copolymer rubber having a value of g*η smaller than 1, it is thought that a crosslinked structure exists in addition to the short chain branching caused by α-olefin, which is a copolymerization component with ethylene. However, since this copolymer rubber is soluble in boiling n-hexane, it cannot be considered a highly crosslinked product. Since it has such a structure, it is presumed that the copolymer rubber has good processability. In addition, the Q value of the copolymer rubber used is generally in the range of about 2 to 6, and a value of about 5 or less provides particularly good sponge strength, and in particular, a value of about 5 or less provides excellent sponge strength and processability. The range is approximately 2.5 to 5. Sponge is generally made by mixing copolymer rubber, filler, softening agent, etc. using a mixer such as a Banbury mixer, and then adding a vulcanizing agent and a blowing agent to approximately 40 to 80 ml using a roll. An unvulcanized, unfoamed rubber compound is prepared by additional mixing at a temperature of °C, and then heated using a mold or in a vulcanization tank that allows free expansion after being molded into a certain shape. It is manufactured by vulcanization and foaming. Fillers include SRF, GPF, FEF, HAF,
Either reinforcing fillers such as carbon black such as ISAF, SAF, FT, MT and finely divided silicic acid, or non-reinforcing fillers such as light calcium carbonate, heavy calcium carbonate, talc and clay can be used. These fillers are generally used in an amount of about 20 to 200 parts by weight per 100 parts by weight of the copolymer rubber. Examples of softeners include process oils, lubricating oils, paraffin, liquid paraffin, petroleum-based substances such as petroleum asphalt and petrolatum, coal tars such as coal tar and coal tar pitch, castor oil, linseed oil, rapeseed oil, Fatty oils such as coconut oil, tall oil, waxes such as beeswax, carnauba wax, and lanolin, ricinol,
Fatty acids or metal salts thereof such as palmitic acid, barium stearate, calcium stearate, and zinc laurate, synthetic polymer substances such as petroleum resins, atactic polypropylene, and coumaron indene resins are used. Among these softeners, petroleum-based substances are preferred, and process oils are particularly preferred. Softener is copolymer rubber 100
About 10 parts by weight or more, preferably about 30 parts by weight
It is commonly used in a proportion of 150 parts by weight. Furthermore, sulfur compounds or organic peroxides are generally used as the vulcanizing agent. As the sulfur compound, for example, sulfur, sulfur monochloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate, etc. are used, and the use of sulfur is particularly preferred. These sulfur compounds are used in an amount of about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight, per 100 parts by weight of the copolymer rubber. When using a sulfur compound as a vulcanizing agent, it is preferable to use a vulcanization accelerator in combination. Examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazole-sulfenamide, N-oxydiethylene-2-benzothiazole-sulfenamide, N,N-diisopropyl-2-benzothiazole-sulfenamide, and 2-mercabutene. Benzothiazole, 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole,
Thiazole systems such as dibenzothiazole-disulfide; guanidine systems such as diphenylguanidine, triphenylguanidine, diorthotolylguanidine, orthotolyl biguanide, diphenylguanidine, and phthalate; acetaldehyde-aniline condensation products, butyraldehyde-aniline condensation products , hexamethylenetetramine, aldehyde-amines or aldehyde-ammonia systems such as acetaldehyde-ammonia;
Imidazolines such as 2-mercaptoimidazoline; thioureas such as thiocarbanilide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram Thiuram series such as disulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide; zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, di-n-
Dithioate salts such as zinc butyl dithiocarbamate, zinc ethyl phenyl dithiocarbamate, zinc butylphenyl dithiocarbamate, sodium dimethyl dithiocarbamate, selenium dimethyl dithiocarbamate, tellurium diethyldithiocarbamate; xanthate series such as zinc dibutyl xanthate; others Examples include zinc carbonate, stearic acid, and zinc stearate. These vulcanization accelerators are used in an amount of about 0.1 to 20 parts by weight, preferably about 0.2 to 10 parts by weight, per 100 parts by weight of the copolymer rubber. Examples of organic peroxides include 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)hexyne-3, di-tert-butyl peroxide, di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butyl hydroperoxide, etc. are used. In particular, dicumyl peroxide/di-tert-butyl peroxide and di-tert-butyl peroxide-3,3,5-trimethylcyclohexane are preferably used. These organic peroxides are
It is used in an amount of about 0.1 to 10 parts by weight, preferably about 0.5 to 8 parts by weight, per 100 parts by weight of copolymer rubber. When using organic peroxides as vulcanizing agents,
It is preferable to use a vulcanization aid in combination. As a vulcanization aid,
For example, sulfur, quinone dioxime systems such as p-quinone dioxime, methacrylate systems such as polyethylene glycol dimethacrylate, allyl systems such as diallyl phthalate and triallyl cyanurate, other maleimide systems, and divinylbenzene are used. Such a vulcanization aid is used in a proportion of about 0.5 to 2 moles, preferably about 1 mole, per mole of organic peroxide used. As blowing agents, inorganic blowing agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, and ammonium nitrite;
Nitroso compounds such as N,N'-dimethyl-N,N'-dinitrosoterephthalamide, N,N'-dinitrosopentamethylenetetramine, azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene , azo compounds such as barium azodicarboxylate, sulfonyl hydrazide compounds such as benzenesulfonylhydrazide, toluenesulfonylhydrazide, p,p'-oxybis(benzenesulfonylhydrazide), diphenylsulfone-3,3'-disulfonylhydrazide, calcium Azide, 4,4'-diphenyldisulfonyl azide, p
-Azide compounds such as toluenesulfonyl azide are used. These blowing agents are used in an amount of about 0.5 to 30 parts by weight, preferably about 1 to 15 parts by weight, per 100 parts by weight of the copolymer rubber. Further, if necessary, a foaming aid can be used in combination with these foaming agents. As foaming aids that lower the decomposition temperature of the foaming agent, promote decomposition, and homogenize bubbles, organic acids such as salicylic acid, phthalic acid, stearic acid, and oxalic acid, urea or its derivatives, etc. are used. . In addition to these, anti-aging agents, thickeners, and other additives may be added as appropriate. The sponge according to the present invention, which is manufactured with good extrusion moldability and vulcanizability, has excellent rubber strength and surface smoothness, so it can be used for various purposes by effectively utilizing these properties. , for example, insulation materials for covering copper pipes through which heat medium passes through air conditioners, insulation materials for covering water pipes, door weather strips for automobile parts, and various sealing materials such as trunk seals. Preferably used for cushioning materials, soundproofing materials, etc. Next, the present invention will be explained with reference to examples. Example 1 Ethylene-propylene-5-ethylidene-2-norbornene produced by the method described in Japanese Patent Application No. 57-74613. 5-vinyl-2-norbornene copolymer rubber (ethylene content 97.5 mol%,
Iodine value 22.5, polyene copolymerization molar ratio 8, [η]
2.83 dl/g, Q value 2.8, g* η0.78), various compounding agents were blended in the following proportions. Copolymer rubber 100 parts by weight Process oil (Kyodo Oil Products Sonics)
P200） 60 SRF Carbon Black (Tokai Carbon Product Seast S) 100 parts by weight Sulfur 2 Vulcanization accelerator (2-mercaptobenzothiazole) 1.5 〃 (Tetramethylthiuram tetrasulfide) 0.8 〃 (Dipentamethylenethiuram tetrasulfide) (Teryllium diethyldithiocarbamate) Foaming agent [p,p'-oxybis(benzenesulfonyl hydrazide)] 3 Zinc oxide 5 Stearic acid 2 When blending, first, copolymer rubber, process oil, zinc oxide , stearic acid, and SRF carbon black were kneaded for 6 minutes in a 4.3 Banbury mixer (Model OOC, manufactured by Kobe Steel, Ltd.), and left in an atmosphere of 30° C. or lower for 1 day. Next, sulfur, a vulcanization aid, and a foaming agent were added to this kneaded product, and the mixture was kneaded for 10 minutes using a 14-inch open roll. The roll processability of the compounded rubber at this time was evaluated according to the evaluation criteria shown in FIG. Rating: E: Excellent 〃G: Good 〃F: Fair 〃P: Poor Next, the temperature of the die and barrel of this compounded rubber was controlled at 60℃, and the screw temperature was controlled at 40℃.
Extrusion is performed using a 60mm diameter extruder, and the molded product is then continued.
The mixture was continuously introduced into a hot air bath controlled at 220° C. and heated for 5 minutes to cause vulcanization and foaming, thereby forming a tubular foam whose cross-sectional end view is shown in FIG. 2. The tubular foam thus obtained has a wall thickness of 2 mm in the tubular portion, an inner diameter of 16 mm if the shape is not deformed, and a width of the flat plate portion of 20 mm. About this foam,
The apparent specific gravity (D) was measured according to the method specified in the expanded rubber physical test method of the Japan Rubber Association standard. In addition, a No. 3 dumbbell-shaped test piece was punched out in the length direction of the tubular part of this foam, and tested at a tensile rate of 500 mm/min at 25°C according to the method specified in JIS K-6301.
Under these conditions, the maximum tensile stress until breakage was determined and measured as tensile strength (TS). Furthermore, as a guide to the vulcanization speed of the compounded rubber, the compounded rubber sheet before vulcanization and foaming was used, and an oscillating disk rheometer (manufactured by Toyo Seiki) was used.
Time to reach 90% of effective torque (T ₉₀ )
I asked for In addition, the smoothness of the surface skin of the sponge,
Evaluation was made according to the following evaluation criteria. Rating 5: There are no irregularities on the surface, and the gloss is good. 〃4: There are almost no irregularities on the surface, and there is no gloss. 〃3: There are slight irregularities on the surface, and there is no gloss. 〃2: There are irregularities on the surface, and there is no gloss. None 〃1: Large irregularities on the surface and no gloss at all Example 2 Another copolymer rubber produced in the same manner as in Example 1 (ethylene content 68.0 mol%, iodine value 23.0, polyene copolymerization molar ratio) 6.7, [η]2.86
dl/g, Q value 3.0, g* η0.65) was used. Example 3 Another copolymer rubber produced in the same manner as in Example 1 (ethylene content 67.8 mol%, iodine value 24.3, polyene copolymerization molar ratio 4, [η] 2.80)
dl/g, Q value 4.6, g* η0.55) was used. Comparative Example 1 In Example 1, another copolymer rubber (ethylene content 68.3 mol%, iodine value 22.3, polyene copolymerization molar ratio 0.8, [η] 2.85 dl/g, Q value 7.5, g* η
0.20) was used. Comparative Example 2 In Example 1, ethylene/propylene/5-ethylidene-2-norbornene copolymer rubber (ethylene content 67.0 mol%, iodine value 22.0, [η] 2.75 dl/g, Q value 2.6, g* η
0.93) was used. Comparative Example 3 In Example 1, ethylene-propylene-dicyclobentazine copolymer rubber (ethylene content 68.5 mol%, iodine value 35.0,
[η] 2.90 dl/g, Q value 5.7, g* η0.36) were used. In the above Examples 2 to 3 and Comparative Examples 1 to 3,
Measurements and evaluations similar to those in Example 1 were performed. The results for both Example 1 and Example 1 are shown in the following table. 【table】

[Brief explanation of drawings]

FIG. 1 shows evaluation criteria for roll processability of compounded rubber. Moreover, FIG. 2 is a cross-sectional end view of a tubular foam as a sample for various measurements and evaluations. Explanation of symbols: 1, 1'...Roll, 2...Rubber being rolled.

Claims (1)

[Scope of Claims] 1 Consists of ethylene/α-olefin and polyene, (a) the copolymerization molar ratio of ethylene and α-olefin is 55/45 to 95/5, (b) the polyene is 5- ethylidene-2-norbornene (ENB) and 5-vinyl-2-norbornene (VNB), the copolymerization molar ratio (ENB/VNB) of 1 to 20; (c) copolymerization of these polyene components; Vulcanized ethylene/α-olefin/polyene copolymer rubber with an iodine value of 2 to 40, and (d) an intrinsic viscosity [η] of 1.0 to 6.0 dl/g (135°C, in delican). , a sponge manufactured by foaming. 2. The sponge according to claim 1, wherein a copolymer rubber having a Q value representing the ratio of weight average molecular weight to number average molecular weight is 6 or less.