JP2000302904A - Rubber composition for sponge, and vulcanized, foamed and molded product of rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition for a sponge rubber having both excellent dimensional stability and foamability, and further to provide a vulcanized foamed and molded product. SOLUTION: This rubber composition for a sponge comprises (A) 100 pts.wt. copolymer rubber component comprising ethylene, a 3-20C α-olefin and a nonconjugated polyene, and characterized by (a) molar ratio [ethylene/α-olefin] of the ethylene to the 3-20C α-olefin regulated so as to be (40/60)-(90/10), (b) 1-50 content of the nonconjugated polyene expressed in terms of iodine value, and (c) 0.7-5 dl/g intrinsic viscosity [η] measured at 135 deg.C in decalin, and (B) 3-40 pts.wt. crystalline or amorphous synthetic resin, and is featured in the decrease of 5-40 points of Mooney viscosity at 100 deg.C after heat treatment compared to the one before the heat treatment when the heat treatment is carried out in 200 deg.C atmosphere for 10 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sponge rubber, and more particularly, to a specific crystalline or amorphous resin dispersed in an ethylene / α-olefin / non-conjugated polyene copolymer rubber in a flat state. And vulcanized and foamed at a temperature equal to or higher than the melting point of the crystalline resin or the glass transition temperature of the amorphous resin.

[0001]

BACKGROUND OF THE INVENTION Conventionally, ethylene / α-olefin copolymer rubber and ethylene / α-olefin / non-conjugated diene copolymer rubber have no unsaturated bond in the main chain.
Excellent in weather resistance, heat resistance, and ozone resistance compared to diene rubber, and widely used in rubber products such as automotive parts, industrial rubber products, electrical insulation materials, civil engineering building materials, and rubberized cloth. I have. In recent years, as each component has a higher performance and a higher function, for example, a weather strip sponge, which is one of the automotive industry components, has been complicated in shape.

In this product, a rubber unvulcanized rubber compound containing a reinforcing material, a vulcanizing agent and a foaming agent is extruded from an ethylene / α-olefin copolymer by an extruder, and vulcanized and foamed in a vulcanizing tank. I have. At this time, the extruded shape is dull due to the weight of the compound before being vulcanized after being extruded. Therefore, it is very difficult to adjust the base because the extruded shape and the shape of the sponge actually formed are significantly different. Therefore, there has been a demand for a compound having a good shape retention property.

[0003] As a formulation for improving the shape retention of the compound, it is conceivable to increase the viscosity of the compound, but the foaming property is remarkably deteriorated. Therefore, as described in Japanese Patent Publication No. 2-62582 and the like, a non-conjugated diene that generates long-chain branching during polymerization of ethylene / α-olefin copolymer rubber is copolymerized with such a demand. And the shape retention of the compound has been improved.

However, in actual sponge rubber production sites, even if such a copolymer rubber is used, the shape retention is not sufficiently improved. Unnecessary sag prevention parts are extruded on the cross section of the cross section and removed after vulcanization and foaming. For this reason, an extra material is required, and disposal of the generated waste material is a problem.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems associated with the prior art as described above, wherein a specific crystalline or non-crystalline resin is mixed with an ethylene / α-olefin / non-conjugated polyene. A sponge having excellent shape retention and foaming properties by being dispersed in a flattened state in a polymer rubber and vulcanizing and foaming at a temperature higher than the melting point of the crystalline resin or the glass transition temperature of the amorphous resin. It is intended to provide rubber.

[0006]

SUMMARY OF THE INVENTION A rubber composition for a sponge according to the present invention is an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) comprising ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated polyene. ) Is (a) a molar ratio of ethylene to an α-olefin having 3 to 20 carbon atoms [ethylene / α-olefin] is 60/40 to 90/1.
0, (b) the content of non-conjugated polyene copolymerized as the third component is 1 to 50 in terms of iodine value, and (c) the intrinsic viscosity [η] measured in decalin at 135 ° C. is 0.7 to 5 dl.
/ G, based on 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) and a crystalline or amorphous synthetic resin (B).
Is heat-treated in a 200 ° C. atmosphere for 10 minutes, and then cooled at 25 ° C. for 5 minutes. As a result, the Mooney viscosity at 100 ° C. after the heat treatment is 5-4
It is characterized by a decrease of 0 points.

The rubber composition for a sponge according to the present invention comprises the above-mentioned crystalline or amorphous synthetic resin (B),
(D) Melting point (T) measured by DSC (differential scanning calorimeter)
m) is from 100 to 190 ° C., or the glass transition temperature (T
g) is 70 to 170 ° C., and (e) the melt flow rate (230 ° C., 2.16 kg load, 10 minutes) is 1 to 5
00 or less.

The sponge rubber composition according to the present invention is characterized in that the crystalline or amorphous synthetic resin (B) is
(F) it is dispersed in the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) in a flat state,
(G) its average dispersion minor axis is 0.01 to 50 μm, (h)
The aspect ratio (major axis / minor axis) is 3 or more and 100 or less.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The rubber composition for sponge and the vulcanized rubber foam molded article thereof according to the present invention will be specifically described below.

The rubber composition for a sponge according to the present invention comprises:
It comprises an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) and a crystalline or amorphous synthetic resin (B). The composition may contain a foaming agent (C), a vulcanizing agent (D), a vulcanization accelerator, a vulcanization aid, and the like, if necessary, in addition to these components.

[0011] Ethylene / α-olefin / non-conjugated polyether
Copolymer rubber (A) The ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) used in the present invention is composed of ethylene and carbon
It is a polymer in which 20 α-olefins and a non-conjugated polyene are randomly copolymerized.

As the α-olefin, specifically, propylene, 1-butene, 1-pentene, 1-hexene,
4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1- Heptadecene, 1-octadecene, 1-nonadecene,
1-eicosene and the like. Among them, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene are preferred. That is, ethylene / propylene / non-conjugated polyene copolymer rubber, ethylene / 1-butene / non-conjugated polyene copolymer rubber, ethylene / 4-methyl-1-pentene / non-conjugated polyene copolymer rubber, ethylene / 1- Hexene / non-conjugated polyene copolymer rubber and ethylene / 1-octene / non-conjugated polyene copolymer rubber are preferably used.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) has a molar ratio of ethylene to an α-olefin having 3 to 20 carbon atoms [ethylene / α-olefin].
Is 40/60 to 90/10, preferably 60/4.
It is desirable to be in the range of 0 to 85/15. It is preferable that the ethylene content be within the above range because the low-temperature flexibility and rubber strength are good.

As the non-conjugated polyene, a cyclic or chain non-conjugated polyene is used. As the cyclic non-conjugated polyene, specifically, 5-ethylidene-2-
Examples include norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, norbornadiene, and methyltetrahydroindene. Examples of the chain non-conjugated polyene include 1,4-hexadiene and 7-methyl-
1,6-octadiene, 4-ethylidene-1,6-octadiene, 7
-Methyl-4-ethylidene-1,6-octadiene, 7-methyl-4-
Ethylidene-1,6-nonadiene, 7-ethyl-4-ethylidene-
1,6-nonadiene, 6,7-dimethyl-4-ethylidene-1,6-octadiene, 6,7-dimethyl-4-ethylidene-1,6-nonadiene, 4-ethylidene-1,6-decadiene, 7- Methyl-4-ethylidene-1,6-decadiene, 7-methyl-6-propyl-4-ethylidene-1,6-octadiene, 4-ethylidene-1,7-nonadiene, 8-methyl-4-ethylidene-1, 7-nonadiene, 4-ethylidene-1,7-undecadiene, 8-methyl-4-ethylidene-1,7
-Undecadiene, 7,8-dimethyl-4-ethylidene-1,7-nonadiene, 7,8-dimethyl-4-ethylidene-1,7-decadiene, 7,8-dimethyl-4-ethylidene-1,7-undecadiene ,
8-methyl-7-ethyl-4-ethylidene-1,7-undecadiene, 7,8-diethyl-4-ethylidene-1,7-decadiene, 9-methyl-4-ethylidene-1,8-decadiene, 8, 9-dimethyl-4-
Ethylidene-1,8-decadiene, 10-methyl-4-ethylidene-
1,9-undecadiene, 9,10-dimethyl-4-ethylidene-1,9
-Undecadienes, 11-methyl-4-ethylidene-1,10-dodecadienes, 10,11-dimethyl-4-ethylidene-1,10-dodecadienes, and the like.

These non-conjugated polyenes can be used alone or
The iodine value is preferably 1 to 50, preferably 5 to 40, and more preferably 10 to 30 in terms of iodine value. When the copolymerization amount of the non-conjugated polyene is within the above range, thermal stability at high temperature,
Sponge rubber is preferable because of good physical properties and foaming properties.

The intrinsic viscosity [η] of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) used in the present invention measured in decalin at 135 ° C. is 0.7 to 5.0.
dl / g, preferably 1.5 to 4.0 dl / g. When the intrinsic viscosity [η] is within the above range,
Workability, rubber elasticity, etc. are favorable and preferable.

In the present invention, the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) can be used alone or in combination of two or more.

Ethylene α-having the above-mentioned properties
The olefin / non-conjugated polyene copolymer rubber (A)
"New Polymer Manufacturing Process" published by the Industrial Research Institute (P
365-380) and the like, and can be prepared by a conventionally known method.

Synthetic Resin (B) The crystalline or amorphous synthetic resin (B) used in the present invention has a melting point (Tm) of 100 to 190 ° C. measured by DSC (differential scanning calorimeter) or a glass transition. The temperature (Tg) is 70-170 ° C. When the melting point (Tm) or glass transition temperature (Tg) of the crystalline or amorphous synthetic resin (B) is within the above range, foamability, compression set, and the like are good, and thus it is preferable.

Specific examples of such a crystalline or amorphous synthetic resin (B) include crystalline resins such as polyethylene, polypropylene, polybutene-1, and polyacetal. Examples of the amorphous resin include polystyrene and polycarbonate.

According to the present invention, the crystalline or non-crystalline synthetic resin (B) has a melt flow rate (230 ° C.,
2.16 kg load, 10 minutes) is 1 or more and 500 or less, more preferably 5 or more and 500 or less. It is preferable that the melt flow rate is within the above-mentioned range because the compression set and the foamability of the sponge are good.

According to the present invention, the crystalline or amorphous synthetic resin (B) is added in an amount of 3 to 40 parts by weight based on 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A). Parts, more preferably 5 to 35 parts by weight.

In the rubber composition of the present invention, the crystalline or non-crystalline synthetic resin (B) comprises ethylene.α
-It is dispersed in the olefin / non-conjugated polyene copolymer rubber (A) in a flat state. The average dispersion minor axis is 0.01 to 50 μm, and the aspect ratio (major axis / minor axis) is 3 or more and 100 or less. When the aspect ratio (major axis / minor axis) is within the above range, the compound viscosity is appropriate, the workability is good, and the effect of improving shape retention is large, which is preferable. The average dispersion diameter of the synthetic resin (B) dispersed in the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) can be determined by dyeing a piece of the elastomer with a heavy metal and using a transmission electron microscope or the like. Can be determined from a photograph taken with an electron microscope.

In the present invention, the crystalline or amorphous synthetic resin (B) dispersed in the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) has an aspect ratio (major axis / minor axis) of 3 The sponge rubber composition having a molecular weight of 100 or less is obtained by preparing a crystalline or amorphous synthetic resin (B) in an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) in a micro-dispersed and molten state. It can be obtained by applying shear and cooling.

As a specific method, for example, using a single-screw or twin-screw extruder, an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) is mixed with a molten crystalline or amorphous synthetic resin. (B) is mixed, and then the extruded strand is rapidly cooled with cooling water at a high speed, or the above (A) and (B) are melt-mixed using a closed kneader such as a Banbury mixer and discharged from the kneader. It can be obtained by, for example, a method of immediately cooling with an open roll in a state where the resin is molten.

Foaming agent (C) The foaming agent (C) used in the present invention is selected from inorganic foaming agents, nitroso foaming agents, azo foaming agents, and sulfonyl hydrazide foaming agents. These foaming agents (C) are used as a mixture of at least one or more.

Examples of the foaming agent (C) include inorganic foaming agents such as sodium hydrogencarbonate (baking soda), sodium carbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite, and the like, N, N'-dinitroso.・ Pentamethylene ・ tetramine (DPT), N, N'-dimethyl-N, N'-
Nitroso foaming agents such as dinitrosoterephthalamide,
Azo-based blowing agents such as azodicarbonamide (ADCA), azobis-isobutyronitrile (AZDN), azocyclohexylnitrile, azodiaminobenzene, barium azodicarboxylate, benzene-sulfonyl-
Hydrazide (BSH), p, p'-oxybis (benzene /
Sulfonyl hydrazide) (OBSH), toluene
Sulfonyl hydrazide (TSH), sulfonyl hydrazide foaming agents such as diphenylsulfone-3,3'-disulfonyl hydrazide, and the like can be mentioned.

These blowing agents (C) are used in an amount of 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, per 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A).
Used in parts by weight.

If necessary, a foaming aid may be used in combination with the foaming agent (C). Examples of the foaming aid that acts to lower the decomposition temperature of the foaming agent (C), accelerate the decomposition, and homogenize the bubbles include organic acids such as salicylic acid, phthalic acid, stearic acid, and oxalic acid, urea, and derivatives thereof. No.

These foaming aids are used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A).
Although it is used in a proportion of 5 parts by weight, it is desirable to appropriately determine the optimum amount according to the required physical property values.

Vulcanizing Agent (D) Specific examples of the vulcanizing agent (D) used in the present invention include sulfur, sulfur compounds and organic peroxides.

Specific examples of the sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur. Specific examples of the sulfur-based compound include sulfur chloride, sulfur dichloride, polymer polysulfide, and the like. In addition, sulfur compounds that release active sulfur at the vulcanization temperature and vulcanize, specifically, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, selenium dimethyldithiocarbamate and the like Is mentioned. Of these, sulfur is preferably used. Vulcanizing agent (D)
Is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A).

[0033] When using a sulfur compound as a vulcanization accelerator also vulcanizing agent, it is preferable to use a vulcanization accelerator. As the vulcanization accelerator,
Specifically, sulfonamides such as N-cyclohexyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, and N, N'-diisopropyl-2-benzothiazolylsulfenamide Phenamide compounds, 2-mercaptobenzothiazole, 2- (2 ', 4'-dinitrophenyl) mercaptobenzothiazole, 2- (4'-
Thiazole compounds such as morpholinodithio) benzothiazol and dibenzothiazyldisulfide; guanidine compounds such as diphenylguanidine, diorthotrileguanidine, diolsonitrileguanidine, orthonitrile biguanide and diphenylguanidine phthalate; acetaldehyde -Aniline reactant, butyraldehyde-aniline condensate, aldehyde amine or aldehyde such as hexamethylenetetramine, acetaldehyde ammonia
-Ammonia compounds, imidazoline compounds such as 2-mercaptoimidazoline, thiourea compounds such as thiocarbanilide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea, tetramethylthiuram monosulfide, tetramethylthiuram disulfide , Thiuram-based compounds such as tetraethylthiuram disulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc di-n-butyldithiocarbamate, zinc ethylphenyldithiocarbamate, butylphenyldithiocarbamate Zinc, sodium dimethyldithiocarbamate, selenium dimethyldithiocarbamate, dimethyldithiocarbamine Dithio acid salt-based compounds of tellurium, Zante such dibutyltin xanthate zinc - DOO compounds, zinc white, may be mentioned compounds such as. These vulcanization accelerators are ethylene, α-olefin,
It is 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 non-conjugated polyene copolymer rubber (A).

Organic peroxide Any organic peroxide may be used as long as it is usually used for peroxide vulcanization of rubber. Specifically, dicumyl peroxide, di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butyl hydroperoxide, t-butylcumyl peroxide, benzoyl Peroxide, 2,5-dimethyl-2,5-di (t-butylperoxin) hexyne-3,2,5-dimethyl-2,
5-di (benzoylperoxy) hexane, 2,5-dimethyl
-2,5-Mono (t-butylperoxy) -hexane, α, α '
-Bis (t-butylperoxy-m-isopropyl) benzene and the like. Among them, dicumyl peroxide, di-t-butyl peroxide and di-t-butylperoxy-3,3,5-trimethylcyclohexane are preferably used.

These organic peroxides are used alone or in combination of two or more. Organic peroxide is ethylene / α-olefin / non-conjugated polyene copolymer rubber (A)
It is used in the range of 0.0003 to 0.05 mol, preferably 0.001 to 0.03 mol per 100 g,
It is desirable to appropriately determine the optimum amount according to the required physical properties.

[0036] When using an organic peroxide as vulcanizing agent vulcanizing agent, it is preferable to use a vulcanization aid. Specific examples of the vulcanization aid include sulfur, quinone dioxime compounds such as p-quinone dioxime, methacrylate compounds such as polyethylene glycol dimethacrylate, diallyl phthalate and triallyl cyanurate. And allyl-based compounds, other maleimide-based compounds, divinylbenzene, and the like. Such a vulcanization aid is used in an amount of 0.5 to 2 mol, preferably about equimolar, per 1 mol of the organic peroxide used.

Other Compounding Agents In the present invention, ethylene / α-olefin / non-conjugated polyene copolymer rubber (A), crystalline or amorphous synthetic resin (B), foaming agent (C), vulcanizing agent In addition to (D), the types and amounts of rubber reinforcing agents, fillers, and softeners, and, if necessary, the types and amounts of antioxidants and processing aids, and the process of producing vulcanizates. Can be appropriately selected.

Rubber Reinforcing Agent The above-mentioned rubber reinforcing agent has an effect of improving mechanical properties such as tensile strength, tear strength and abrasion resistance of the vulcanized rubber. As such a rubber reinforcing agent, specifically, SR
F, GPF, FEF, MAF, HAF, ISAF, SA
Examples thereof include carbon blacks such as F, FT, and MT, and carbon blacks, silica, activated calcium carbonate, fine talc, and fine silicic acid, which have been surface-treated with a silane coupling agent.

Filler The above-mentioned filler has little effect on physical properties.
Used to increase the hardness of rubber products and reduce costs. As such a filler,
Specific examples include light calcium carbonate, heavy calcium carbonate, talc, clay and the like. The types and amounts of these rubber reinforcing agents and fillers can be appropriately selected depending on the application.
-Olefin / non-conjugated polyene copolymer rubber (A) 10
300 parts by weight or less, preferably 200 parts by weight with respect to 0 parts by weight
Not more than parts by weight.

Softener As the above-mentioned softener, a softener usually used for rubber can be used. Specifically, petroleum softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petrolatum, coal tar, core
Cooler-based softeners such as rutar pitch; fatty oil-based softeners such as castor oil, linseed oil, rapeseed oil, and coconut oil; waxes such as tall oil, sub, beeswax, carnauba wax, and lanolin And fatty acid salts such as ricinoleic acid, palmitic acid, barium stearate, calcium stearate and zinc laurate, and synthetic high molecular substances such as petroleum resins, atactic polypropylene and coumarone indene resins. Among them, a petroleum softener is preferably used, and particularly, a process oil is preferably used. The compounding amount of these softeners can be appropriately selected depending on the use of the vulcanized product, but the compounding amount is usually 150 parts by weight based on 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A). It is at most 100 parts by weight, preferably at most 100 parts by weight.

Anti- aging agent If an anti-aging agent is used, the material life can be further extended. This is similar to the case of normal rubber. As the antioxidant used in this case, specifically, phenylnaphthylamine, 4,4 ′-(α,
α'-dimethylbenzyl) diphenylamine, N, N'-di-2-
Aromatic secondary amine stabilizers such as naphthyl-p-phenylenediamine, 2,6-di-t-butyl-4-methylphenol, tetrakis- [methylene-3- (3 ′, 5′-di-t- Phenol-based stabilizers such as butyl-4′-hydroxyphenyl) propionate] methane, and thioether-based stabilizers such as bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tbutylphenyl] sulfide; Benzimidazole stabilizers such as 2-mercaptobenzimidazole, dithiocarbamate stabilizers such as nickel dibutyldithiocarbamate, quinoline stabilizers such as a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline, And the like. At least one of these antioxidants is used in combination.

Such anti-aging agents include ethylene α-
Olefin / non-conjugated polyene copolymer rubber (A) 100
It is used in a proportion of 5 parts by weight or less, preferably 3 parts by weight or less with respect to parts by weight, but it is desirable to appropriately determine an optimal amount according to required physical properties.

Processing Aids As processing aids, compounds used in normal rubber processing can be used. Specific examples include ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, zinc stearate, calcium stearate, higher fatty acids such as esters of the above acids, salts thereof, and esters thereof. . Such a processing aid is used in an amount of 10 parts by weight based on 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A).
It is used in a proportion of not more than 5 parts by weight, preferably not more than 5 parts by weight, but it is desirable to determine an optimum amount appropriately according to the required physical property values.

In the case of vulcanizing the defoamer compounded rubber, or can bubbles by moisture contained, to or different foaming degree, may be added calcium oxide as a defoaming agent. Such a defoamer,
It is used in an amount of 10 parts by weight or less, preferably 5 parts by weight or less with respect to 100 parts by weight of the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A). It is desirable to determine the amount.

Rubber composition for sponge and vulcanized rubber foam
Preparation of Molded Article The rubber composition for a sponge and the vulcanized rubber foam molded article of the present invention can be prepared, for example, by the following method. First, an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A), which is an essential component of the present invention, and a molten crystalline or amorphous synthetic resin (B) are mixed, for example, with a single-screw or twin-screw extruder. By mixing at 200 ° C. to 250 ° C. for 20 seconds to 4 minutes, and then extruding the strand at a high speed from 10 ° C. to 50 ° C.
180 ° C to 230 ° C by a method of quenching with cooling water or a closed kneader such as a Banbury mixer.
For 3 minutes to 10 minutes, and after discharging from the kneading machine, immediately after the resin is melted, the mixture is cooled with an open roll having a roll temperature of 20 ° C to 80 ° C. A mixture in which a crystalline or amorphous synthetic resin (B) is dispersed in a flat state in the united rubber (A) can be obtained.

Next, this mixture and additives such as a reinforcing material, a filler and a softening agent are kneaded at a temperature of about 80 ° C. to 180 ° C. for about 3 minutes to 10 minutes using a kneading machine such as a Banbury mixer. In this case, when the kneading temperature exceeds the melting point or the glass transition temperature of the crystalline or amorphous synthetic resin (B), the roll temperature is set to 20 ° C. to 80 ° C. immediately after the resin is melted after being discharged from the kneader. If not cooled with an open roll,
Either crystalline or amorphous synthetic resin (B) in ethylene / α-olefin / non-conjugated polyene copolymer rubber (A)
Cannot obtain a mixture in which the particles are dispersed in a flat state.

Subsequently, additives such as a vulcanizing agent, a vulcanization accelerator and a foaming agent are added to the mixture at 40 ° C. using a kneader such as an open roll.
Knead at 80 ° C. for about 3 to 30 minutes. Finally, the obtained composition is made into a ribbon or pellet according to the post-process,
A rubber composition for a sponge of the present invention is prepared.

The melting point (Tm) and the glass transition temperature (Tg) of the crystalline or amorphous synthetic resin (B) are low, and the kneading temperature in a Banbury mixer or the like is either crystalline or amorphous. If the melting point (Tm) or the glass transition temperature (Tg) of the resin is higher than the melting point (Tm), the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) and the crystalline or amorphous synthetic resin (B) are kneaded. A reinforcing material, a filler, a softener and the like may be simultaneously kneaded. In this case, if the resin is melted after being discharged from the kneader and is not immediately cooled by an open roll having a roll temperature of 20 ° C. to 80 ° C., the ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) Furthermore, a mixture in which the crystalline or amorphous synthetic resin (B) is dispersed in a flat state cannot be obtained.

The thus-prepared unvulcanized rubber compound is molded into a desired shape by an extruder or the like, and after molding, the molded product is treated with a crystalline or amorphous synthetic resin (B ) At 150 ° C. to 270 ° C., which is higher than the melting point (Tm) or the glass transition temperature (Tg), for about 1 minute to 30 minutes. Thereby, vulcanization and foaming are performed to obtain a vulcanized foam molded article of the present invention having a foaming ratio of 1.2 to 20 times.

In this case, as the vulcanizing tank, a hot air vulcanizing tank, a microwave vulcanizing tank, a glass bead fluidized bed, a molten salt vulcanizing tank, a steam vulcanizing tank, or the like can be used. These can be used alone or in combination of two or more.

The thus obtained foamed molded article of the present invention has a good balance between sealing performance and strength properties, and is suitably used for sealing materials and cushioning materials, especially for weather strip sponges for automobiles.

The reason why the rubber composition for a sponge of the present invention is excellent in shape retention and foaming property, and the foamed molded article obtained therefrom has good sealing properties and strength properties is that ethylene / α-olefin / non-conjugated. The crystalline or amorphous synthetic resin (B) dispersed in a flat state in the polyene copolymer rubber (A) exhibits a high viscosity when not vulcanized and exhibits high shape retention, It is presumed that it sometimes melts and functions as a plasticizer, and in a foam molded article, functions as a filler.

[0053]

The rubber composition for a sponge of the present invention is obtained by dispersing a specific crystalline or amorphous synthetic resin in an ethylene / α-olefin / non-conjugated polyene copolymer rubber in a flat state, By vulcanizing and foaming at a temperature equal to or higher than the melting point (Tm) of the crystalline resin or the glass transition temperature (Tg) of the amorphous resin, a sponge rubber having excellent shape retention and foaming properties can be provided. In addition, there is a possibility that it is possible to remove a part of the actual cross section called foot rubber that is unnecessary and has not been set, which was previously installed because the shape retention property was not sufficiently improved at the sponge rubber manufacturing site . Since the foamed molded article of the present invention is composed of the rubber composition for a sponge, the sealing performance and the strength characteristics are balanced.

[0054]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

The measurements in the following Examples and Comparative Examples were performed as follows. 1. Composition: Copolymer composition (ethylene / propylene ratio)
Was measured by 13C-NMR method. 2. Iodine value: determined by a titration method. 3. Intrinsic viscosity [η]: Measured in decalin at 135 ° C.

[0056]

Example 1 First, EPT [ethylene / propylene / non-conjugated polyene (= 5-ethylidene-2-norbornene) copolymer; ethylene / propylene molar ratio = 70/30, 13
Intrinsic viscosity [η] measured in decalin at 5 ° C. = 2.8 dl
/ G, iodine value 23, hereinafter abbreviated as EPT (1)] 100
The melting point (Tm) measured by a polypropylene (propylene-ethylene copolymer; DSC (differential scanning calorimeter) = 158 ° C.) and the melt flow rate (ASTM D 1238, 230 ° C., 2. 16
kg load) = 23 g / 10 min, abbreviated as PP (1)] 20
The weight part is a twin screw extruder (manufactured by Toshiba Machine Co., Ltd .: 50 mmφ)
Twin screw extruder, L / D = 45), set temperature 230 ° C,
The mixture was mixed and kneaded in a molten state at a screw rotation speed of 200 rpm, and extruded from a 3 mmφ (5 holes) die. Next, the blend (hereinafter, blend-A) was continuously cooled in a cooling water bath at 30 ° C., and pellets were obtained with a pelletizer.

This formulation-A was treated with a Mooney viscometer [SMV-201, manufactured by Shimadzu Corporation] at 125 ° C.
Using a S rotor], the value 4 minutes after preheating for 1 minute was 91. Formulation-A was then added to 200
Press molding machine set to ℃ [Kotaki Co., Ltd .: KMF
(50-450 × 450-1E)] for 10 minutes and cooled at 25 ° C. for 5 minutes. The viscosity of this formulation-A was 76 when measured by the Mooney viscometer described above.

Further, a section of Formulation-A was stained with ruthenic acid and scanned with a scanning electron microscope [T33 manufactured by JEOL Ltd .:
0A], a 10,000-fold photograph was taken, and the size of the resin in the photograph was measured with an image analyzer [LA-500 manufactured by Pierce Co., Ltd.]. As a result, the average major axis was 7.2 μm and the average minor axis was Is 0.6 μm and the aspect ratio (average major axis / average minor axis)
Was 12.

Next, 120 parts by weight of the pellet-form compound-A, 5 parts by weight of activated zinc flower (manufactured by Inoue Lime Industry Co., Ltd., trade name: Meta Z102), and stearic acid [manufactured by Kao Corporation]
2 parts by weight, surfactant [manufactured by Lion Akzo Co., Ltd .: trade name ARKARD 2HT-F] 2 parts by weight, SRF carbon black [manufactured by Asahi Carbon Co., Ltd .: trade name Asahi # 50H]
G] 90 parts by weight and a paraffin-based process oil [manufactured by Idemitsu Kosan Co., Ltd .: trade name Diana Process PS-
430] 70 parts by weight were kneaded at 135 ° C for 5 minutes using a 2.95 liter Banbury mixer [BB-4, manufactured by Kobe Steel Ltd.].

After discharge, this formulation-A was treated with a surface temperature of 50
After being wound around a 14-inch roll at a temperature of .degree. Subsequently, 2 parts by weight of 279 parts by weight of the formulation-A
-Mercaptobenzothiazole [manufactured by Sanshin Chemical Co., Ltd .: trade name Suncellar M) 0.8 parts by weight, 2- (4'-morpholinodithio) benzothiazole [Ouchi Shinko Co., Ltd.
Manufactured by: trade name Noxeller MDB] 1.2 parts by weight
Zinc n-butyldithiocarbamate [Sanshin Chemical Co., Ltd.]
2.0 parts by weight, 2-mercaptoimidazoline [manufactured by Sanshin Chemical Co., Ltd .: trade name Suncellor 22-C] 1.0 part by weight, 1.5 parts by weight of sulfur, OBSH-based blowing agent 3.5 parts by weight of [Neoserbon N1000SW manufactured by Eiwa Chemical Industry Co., Ltd.] and 5 parts by weight of a defoaming agent [Vesta 20 manufactured by Inoue Lime Industry Co., Ltd.] were added and kneaded for 8 minutes. Subsequently, the resultant was separated into a ribbon having a thickness of 5 mm and a width of 50 mm to obtain an unvulcanized rubber compound.

The unvulcanized rubber compound was subjected to a die temperature of 80 using a 60 mm extruder [L / D = 16, manufactured by Miba Co., Ltd.] equipped with a tubular die (inner diameter: 10 mm, wall thickness: 1 mm). And extruded at a cylinder temperature of 60 ° C. to form a tube. The molded body was vulcanized in a hot air vulcanization tank at 250 ° C. for 5 minutes to obtain a sponge rubber.

In order to calculate the expansion ratio, a press molding machine (KMF100-600 × 600-manufactured by Kotaki Co., Ltd.) in which the above-mentioned unvulcanized rubber compound was set at 170 ° C.
1E)] for 10 minutes to obtain a non-foamed solid rubber.

The physical properties test of the vulcanized rubber foam and the test method in the examples and comparative examples are as follows. (1) Foaming Ratio A 20 mm × 20 mm test piece was punched out of a tubular sponge rubber vulcanized with hot air and a solid rubber vulcanized with press, and the surface dirt was wiped off with alcohol. The specific gravity of the test piece was measured from the difference between the mass in the air and the mass in pure water using an automatic hydrometer [M-1 type, manufactured by Toyo Seiki Seisakusho] in an atmosphere of 25 ° C., and the expansion ratio of the sponge rubber was calculated. did. (2) Tensile test JIS K6 from tubular sponge rubber cured by hot air
251 (1993) by punching with a No. 3 type dumbbell to obtain a test piece. Using the test piece,
According to the method specified in Section 6301, a tensile test was conducted under the conditions of a measurement temperature of 25 ° C. and a tensile speed of 500 mm / min, and a tensile strength at break TB and an elongation at break EB were measured.

(3) Compression Permanent Strain Test The hot air-cured tube-shaped sponge rubber was cut into a length of 30 mm, and attached to a compression set measuring die. The specimen was compressed so that the height became half the height before applying a load, and the entire mold was placed in a gear oven at 70 ° C.
Heat treated for hours. Remove the test specimen from the compression device and
After allowing to cool for one minute, the height of the test piece was measured, and the compression set was calculated by the following formula. Compression set = (t0−t1) / (t0−t2) × 100
(%) T0: height of test piece before test t1: height after heat treatment of test piece and cooling for 30 minutes t2: height of test piece attached to measurement mold (4) shape retention Ratio The height and width of the inside of the hot-air vulcanized tubular sponge rubber were measured, and the shape retention was calculated by the following formula. Shape retention = H / W × 100 (%) H: Height inside test piece W: Width inside test piece

Table 1 shows the results.

[0066]

Example 2 100 parts by weight of EPT (1) and PP
(1) 20 parts by weight are mixed with the above-mentioned Banbury mixer in 1 part.
The mixture was mixed and kneaded in a molten state at 80 ° C. for 5 minutes, and immediately after being discharged, wound around a 14-inch roll having a surface temperature set at 50 ° C., and treated for 3 minutes to obtain Formulation-B. Thereafter, the same procedure as in Example 1 was performed. Table 1 shows the results.

[0067]

Comparative Example 1 As in Example 2, 20 parts by weight of PP (1) was mixed and kneaded in a molten state at 180 ° C. for 5 minutes with the above-mentioned Banbury mixer with respect to 100 parts by weight of EPT (1). After discharge, the mixture was allowed to stand at room temperature for 16 hours without applying external force, wound around a 14-inch roll having a surface temperature set at 50 ° C., and treated for 3 minutes to obtain Formulation-C. Thereafter, the same procedure as in Example 1 was performed. Table 1 shows the results.

[0068]

[Comparative Example 2] 100 parts by weight of EPT (1), activated zinc white [trade name Meta Z102, manufactured by Inoue Lime Industry Co., Ltd.] 5
2 parts by weight, stearic acid [manufactured by Kao Corporation] 2 parts by weight, surfactant [manufactured by Lion Akzo Co., Ltd .: trade name ARKARD 2HT-F] 2 parts by weight, SRF carbon black [manufactured by Asahi Carbon Co., Ltd .: product Name Asahi # 50HG] 11
0 parts by weight and paraffin-based process oil [manufactured by Idemitsu Kosan Co., Ltd .: trade name Diana Process PS-430]
Using a 2.95 liter Banbury mixer [BB-4, manufactured by Kobe Steel Ltd.], 70 parts by weight of
Kneaded at 35 ° C. for 5 minutes. Molding and processing of the obtained compound were performed in the same manner as in Example 1. Table 1 shows the results.

[0069]

Comparative Example 3 Comparative Example 2 was carried out in the same manner as in Comparative Example 2, except that 130 parts by weight of SRF carbon black was used instead of 110 parts by weight. Table 1 shows the results.

[0070]

Example 3 In Example 2, a melting point (Tm) measured by polybutene-1 [DSC (differential scanning calorimeter) = 123 ° C. as a crystalline resin instead of PP (1) = 123 ° C., and a melt flow rate (ASTM D1238; 230 ° C., 2.16 kg load) = 32 g / 10 min, abbreviated as PB (1)]. Table 1 shows the results.

[0071]

Example 4 In Example 2, polystyrene was used instead of PP (1) as an amorphous resin. Glass transition temperature (Tg) measured by DSC (differential scanning calorimeter) = 99 ° C., melt flow rate (ASTM D1238). , 230 ° C, 2.16
kg load) = 9 g / 10 min., abbreviated as PS (1)]. Table 1 shows the results.

[0072]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // (C08L 23/16 101: 00) F term (reference) 4F070 AA15 AA16 AC05 AC57 AC66 AE08 AE12 GA06 GC04 4F074 AA25 AA97 AA98 AB03 AB05 AG20 BA19 CA29 CC04Y CC06Y DA24 DA35 4J002 BB032 BB051 BB122 BB151 BB172 BC032 CB002 CG002 GJ02 GN00

Claims (5)

[Claims] (A) ethylene and α having 3 to 20 carbon atoms
The molar ratio with ethylene-α-olefin [ethylene / α-olefin] was measured in 40/60 to 90/10, (b) non-conjugated polyene content was measured in decalin at 135 ° C. and (c) 135 ° C. in iodine value. Ethylene and α having 3 to 20 carbon atoms, wherein the intrinsic viscosity [η] is 0.7 to 5 dl / g.
A copolymer rubber component (A) composed of an olefin and a non-conjugated polyene (A) and 100 parts by weight of a crystalline or amorphous synthetic resin (B) at 3 to 40 parts by weight;
A sponge rubber composition characterized in that, when heat-treated in an atmosphere for 10 minutes and then cooled at 25 ° C. for 5 minutes, the Mooney viscosity at 100 ° C. after heat treatment is reduced by 5 to 40 points as compared to before heat treatment. 2. A crystalline or amorphous synthetic resin (B)
However, (d) the melting point (Tm) measured by DSC (differential scanning calorimeter) is 100 to 190 ° C, or the glass transition temperature (Tg) is 70 to 170 ° C, and (e) the melt flow rate (230) ℃, 2.16 kg load, 10 minutes) is 1
The rubber composition for a sponge according to claim 1, wherein the rubber composition is at least 500. 3. A crystalline or amorphous synthetic resin (B) is dispersed in (f) an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) in a flat state,
(G) its average dispersion minor axis is 0.01 to 50 μm;
(H) The aspect ratio (major axis / minor axis) is 3 or more and 100
The rubber composition for a sponge according to any one of claims 1 to 2, wherein 4. A vulcanized rubber foam molded article obtained by vulcanizing and foaming the rubber composition according to claim 1. 5. A vulcanized rubber foam molded article according to claim 4, wherein the foamed molded article after vulcanization foaming has an expansion ratio of 1.2 to 20 times. [0001]