JPS6323218B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber composition for automobile exterior parts comprising a specific ethylene/α-olefin copolymer rubber, a softener and a filler if necessary, and a specific proportion thereof. Recently, with the aim of reducing the weight of automobiles, automobile exterior parts such as bumpers, bumper fillers, bumper rub strips, bumper side guards, overriders, and side protection moldings have been made of plastic, but they are not commonly used. The material is polyurethane, polypropylene, polyolefin such as polyethylene, etc. Although polyurethane has excellent performance, it is expensive, polypropylene has poor impact resistance and brittleness, and polyolefins generally have molding problems that cause sink marks when manufacturing large, thick-walled products such as the above-mentioned automobile exterior parts. Furthermore, there was a problem that the product could easily deform or creep due to external force, making it impossible to maintain the original shape of the product. Weather resistance is a material that can solve these drawbacks.
Impact embrittlement resistance, resilience against deformation caused by external forces,
It is also possible to use vulcanized products of ethylene-propylene copolymer rubber or ethylene-propylene-polyene copolymer rubber, which have excellent rubber properties and do not cause sink marks during molding. The copolymer rubber vulcanizate has a strength, especially tensile stress at break, of 70 kg/cm ² or more, which is the value required for automotive exterior parts, because it is necessary to incorporate a large amount of reinforcing filler such as carbon black. Its use was limited to being used as a protective material for metal bumpers due to extremely poor workability during the process of manufacturing automotive exterior parts and the low surface hardness of the vulcanizate. . However, the present inventor has taken advantage of the advantages of ethylene-propylene copolymer rubber vulcanizates, which have excellent weather resistance, impact embrittlement resistance, and resilience against deformation caused by external forces. As a result of our investigation to find a material that is excellent in carbon The vulcanizate from an ethylene/α-olefin copolymer rubber consisting of α-olefins having a number of 4 to 10 has a molar ratio of ethylene units to α-olefin units (ethylene/α-olefin).
It has significantly higher strength than the vulcanized product of ethylene/propylene copolymer rubber in terms of 80/20 to 95/5, and the amount of softener added to 100 parts by weight of the above-mentioned specific ethylene/α-olefin copolymer is X
When the amount of filler is Y parts by weight,
Vulcanized products made from rubber compositions that satisfy 0≦X+Y≦300 and 0≦X≦75 can easily have a strength at break of 70 kg/cm ² or more, have high hardness, and have rubber-like properties. The present invention was developed based on the knowledge that this material functions satisfactorily as a material for automobile exterior parts. That is, the present invention has a molar ratio of ethylene units to α-olefin units having 4 to 10 carbon atoms (ethylene/α-olefin) of 80/20 to 95/5, and an intrinsic viscosity [η] of 0.6 to 6.0 dl/g. ethylene·
An automobile exterior comprising 100 parts by weight of α-olefin copolymer rubber, X parts by weight of a softener, Y parts by weight of a filler, and a vulcanizing agent, and satisfying 0≦X+Y≦300 and 0≦X≦75. Provides a rubber composition for parts. Automotive exterior parts are manufactured from the composition of the present invention with good workability, and the vulcanizate that is the raw material for the automotive exterior parts has a tensile stress at break of 70 to 400 Kg/cm ² and a hardness [JIS
A) It has practically sufficient strength and hardness of 65 to 100, and has excellent impact embrittlement resistance, resilience against deformation due to external force, weather resistance, and heat resistance, so the automobile exterior manufactured from the composition of the present invention The parts function satisfactorily for practical purposes. In addition, the specific ethylene/α-olefin copolymer rubber of the present invention can be produced by the usual method for producing ethylene/propylene copolymer rubber, and is therefore inexpensive, so the composition of the present invention is not expensive. do not have. The configuration of the present invention will be explained in detail below. The α-olefin which is a component of the ethylene/α-olefin copolymer rubber used in the present invention is an α-olefin having 4 to 10 carbon atoms. Specifically, 1-butene, 1-pentene, 1-hexene, 4-
Examples include methyl-1-pentene, 1-octene, 1-decene, and mixtures thereof, with 1-butene being particularly preferred. And the molar ratio of ethylene units to α-olefin units (ethylene/α-olefin) is 80/20 to 95/5, preferably
Examples include 83/17 to 95/5, more preferably 85/15 to 95/5. In the present invention, this α-
The number of carbon atoms in the olefin and the molar ratio of ethylene to α-olefin are the most important structural requirements, and the use of propylene as the α-olefin is excluded from the present invention because of its insufficient strength. If the molar ratio is larger than 95/5 and there are many ethylene units, the vulcanizate will have a marked tendency to be permanently deformed by external force, and if it is smaller than 80/20, the strength and hardness of the vulcanizate will be insufficient for practical use, so the above range is required. Other copolymer rubbers are excluded from the present invention. The intrinsic viscosity [η] of the ethylene/α-olefin copolymer rubber of the present invention is 0.6 to 6.0 dl/g as a value measured by a multipoint method at 135°C in decalin,
Preferably 0.8 to 4.0 dl/g, more preferably
It is 1.0 to 3.0 dl/g. If [η] is less than 0.6 dl/g, the strength of the vulcanizate will be low, and if it is greater than 6.0 dl/g, the process of manufacturing automotive exterior parts described below, for example, the roll processing process of preparing unvulcanized compounded rubber. Problems arise in the production of automobile exterior parts, such as a decrease in roll workability during the process of forming automobile exterior parts from compounded rubber and a deterioration in moldability due to a decrease in fluidity during the process of molding automobile exterior parts from compounded rubber. The ethylene/α-olefin copolymer rubber of the present invention does not exclude those that do not contain a polyene component, but those that contain a polyene component are preferred. The amount of the polyene component is expressed as an iodine value of 4 to 50, preferably 8 to 40, more preferably 8 to 30.
It is. Particularly when a sulfur compound is used as a vulcanizing agent, a polyene component is essential. Specifically, the polyene component is 1,4-hexadiene,
Chain non-conjugated dienes such as 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, cyclohexadiene, dicyclopentadiene , methyltetrahydroindene,
5-vinylnorbornene, 5-ethylidene-2-
norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene,
Cyclic non-conjugated dienes such as 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-
Diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 1,3,7-octatriene, 1,4,9-
Trienes such as decatriene can be exemplified as a representative example. Suitable polyenes are cyclic non-conjugated dienes and 1,4-hexadiene, especially dicyclopentadiene or 5-ethylidene-2-
It is norbornene. The ethylene/α-olefin copolymer rubber of the present invention can be produced by a conventional method for producing ethylene/propylene copolymer rubber. That is, a Ziegler catalyst such as a soluble vanadium compound and an organoaluminium compound is used in the medium, and ethylene, an α-olefin having 4 to 10 carbon atoms, polyene as necessary, and hydrogen gas as a molecular weight regulator are supplied. Manufactured by. Examples of media include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, and kerosene, alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, chlorobenzene, and tetrachloride. Carbon, halogenated hydrocarbons such as tetrachloroethylene, trichlorethylene, ethyl chloride, methylene chloride, and dichloroethane can be used alone or in combination. 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 (here R is an aliphatic hydrocarbon group,
X represents a halogen atom, and 0<n<3. ) can be used alone or in combination. On the other hand, organoaluminum compounds have the general formula R _n AlX _3-n (where R is an aliphatic hydrocarbon group,
X represents halogen, and 1≦m≦3. )
Compounds represented by, for example, triethylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, etc. can be used alone or in combination. In the present invention, 0≦X+Y≦300 and 0≦X≦, where the amount of the softener is X parts by weight and the amount of filler is Y parts by weight with respect to 100 parts by weight of the copolymer rubber of the present invention. 75, preferably 0≦X+Y≦250 and 0≦X≦50. 0≦X+Y
Even if ≦300, if 75<X and the blending amount of the softener is relatively large, the softener bleeds out to the surface of the vulcanizate from the composition of the present invention, and a decrease in strength is also observed, so it is not suitable for automobile exteriors. If it is not suitable as a material for parts, and if 300 < Not suitable as a rubber composition for parts.
In addition, even if X+Y=0, that is, no softener or filler is blended at all, an automobile exterior part with high strength, high hardness, and rubber-like properties can be produced, and it is one of the preferred compositions of the present invention. . Softeners that can be used in the present invention include those commonly used for rubber, such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petroleum softeners such as petrolatum, coal tar, and coal tar pitch. Coal tar softeners such as castor oil, linseed oil, rapeseed oil,
Fatty oil-based softeners such as coconut oil, tall oil; sub;
Waxes such as beeswax, carnauba wax, and lanolin; Fatty acids and fatty acid salts such as ricinoleic acid, palmitic acid, barium stearate, calcium stearate, and zinc laurate; Synthetic polymers such as petroleum resin, atactic polypropylene, and coumaron indene resin. Can list substances.
Among these, petroleum-based softeners are preferably used, and process oils are particularly preferred. Fillers used in the present invention include SRF,
Inorganic fillers such as carbon black, finely divided silicic acid, calcium carbonate, talc, and clay, which are commonly used in rubbers such as GPF, FET, HAT, ISAF, SAF, FT, and MT, are preferably used. Normally inexpensive non-reinforcing fillers such as calcium carbonate, talc, and clay have the disadvantage of reducing the strength of the vulcanizate when blended, but in the present invention, even such fillers satisfy the above formula. It can be used sufficiently within this range. Vulcanizing agents used in the present invention include sulfur, sulfur compounds such as sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate; 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-butyl peroxy-3,3,
Organic peroxides such as 5-trimethylcyclohexane and tert-butyl hydroperoxide can be mentioned. Among these, it is preferable to use sulfur-based compounds, and the use of sulfur is particularly preferable for producing automotive exterior parts with high strength and high hardness. The amount of the sulfur compound to be used is 0.2 to 5 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the copolymer rubber of the present invention. When an organic peroxide is used as a vulcanizing agent, it is used in an amount of 3 x 10 ^-4 to 5 x 10 ^-2 mol parts, preferably 1.5 x 10 ^-3 to 2.5 x 10 molar parts, based on 100 parts by weight of the copolymer rubber of the present invention. -Use ² molar parts. When using a sulfur compound as a vulcanizing agent, it is preferable to use a vulcanization accelerator in combination. As the 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-(2,6-diethyl-4-morpholinothio)benzothiazole, dibenzo Thiazole series such as thiazole disulfide; diphenylguanidine, triphenylguanidine, diorthotolylguanidine, orthotolyl biguanide, diphenylguanidine.
Guanidine systems such as phthalates; aldehyde amines or aldehyde-ammonia systems such as acetaldehyde-aniline reactants, butyraldehyde-aniline condensates, hexamethylenetetramine, and acetaldehyde ammonia; imidazoline systems such as 2-mercaptoimidazoline; thiocarbanilide, diethylthiourea, Thiourea series such as dibutylthiourea, trimethylthiourea, diorthotolylthiourea; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, bentamethylenethiuram tetra Thiuram series such as sulfides;
Zinc dimethylthiocarbamate, zinc diethylthiocarbamate, zinc di-n-butyldithiocarbamate, zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, selenium dimethyldithiocarbamate, tellurium diethyldithiocarbamate, etc. Examples include dithioate salts; xanthate salts such as zinc dibutylxanthate; and zinc white. These vulcanization accelerators are 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, per 100 parts by weight of the copolymer rubber.
Used in parts by weight. Further, when an organic peroxide is used as a vulcanizing agent, it is preferable to use a vulcanizing aid in combination. Examples of the vulcanization aid include sulfur, quinone dioxime type such as p-quinone dioxime, methacrylate type such as polyethylene glycol dimethacrylate, allyl type such as diallyl phthalate and triallyl cyanurate, and other maleimide type divinylbenzene. Ru. These vulcanization aids are used in an amount of 1/2 to 2 moles, preferably about 1 mole, per mole of the organic peroxide used. In the present invention, other anti-aging agents, colorants,
Lubricants, thickeners, conventional EPDM, EPM, polyolefin resins, diene rubbers, etc. may be blended as long as the strength, hardness, and rubber properties of the automotive exterior parts of the present invention are not lost. In order to manufacture automobile exterior parts from the composition of the present invention, the same method as in the case of using conventional ethylene-propylene copolymer rubber can be arbitrarily selected. That is, after kneading the copolymer rubber of the present invention, a softener, an inorganic filler, and/or carbon black at a temperature of 80 to 150°C for about 4 to 10 minutes using a mixer such as a Banbury mixer, the mixture is kneaded with a roll such as an oven roll. roll temperature using
At a temperature of 60 to 100°C, add a vulcanizing agent and, if necessary, a vulcanization accelerator or vulcanization aid.
The mixture is kneaded for 20 minutes and then dispensed from a roll to prepare a sheet or ribbon of unvulcanized rubber compound. Furthermore, a pelletized unvulcanized rubber compound may be prepared by supplying this compounded rubber to a granulator heated to 80 to 100° C. and setting the residence time to 0.5 to 5 minutes. These unvulcanized compounded rubbers are molded into the shape of the product using an extruder, and simultaneously with the molding or heated in a vulcanization tank for 1 to 60 minutes, or A final product is obtained by molding the unvulcanized compounded rubber using a hot press and simultaneously heating it at the temperature and for the time period. Furthermore, injection molding is preferably used to manufacture automotive exterior parts other than long products such as bumper rub strips and side protection moldings. In this case, the time required for one cycle can be arbitrarily adjusted by the combination and amount of the vulcanizing agent, vulcanization accelerator, or vulcanization aid, but it is preferably 0.5 to 5 minutes per cycle, and the barrel of the injection molding machine Temperature 60~100℃, mold temperature 170~
A temperature of 250°C is recommended. In the case of injection molding, the unvulcanized compounded rubber preferably has a ribbon-like or pellet-like shape. The composition of the present invention can also be used to manufacture sheets, hoses, gaskets, packings, etc., but the vulcanizate must have a hardness of JIS A of 65 or higher and a tensile stress at break of 70 kg/cm ² or higher. The composition of the present invention is most suitable for manufacturing automobile exterior parts. Examples will be specifically described below. Examples 1 to 5, Comparative Examples 1 to 3 The ethylene/α-olefin/5-ethylidene-2-norbornene copolymer rubber, zinc white, vulcanization accelerator, stearic acid as a lubricant, and sulfur listed in Table 2 were used for each. Using an 8-inch oven roll at the ratio listed in Table 1 at a roll surface temperature of 70°C.
The mixture was kneaded for 10 minutes to prepare 1000 g of unvulcanized compounded rubber. After leaving this compounded rubber at room temperature for 24 hours, it was injected into a mold kept at 200°C using an injection molding machine (RJ-75B; Meiki Seisakusho) at a barrel temperature of 70°C, and vulcanization time was 1 minute. That is, molding and vulcanization were performed in one cycle time of 1 minute to produce a sheet of 150 mm x 110 mm x 2 mm. After leaving this sheet in a constant temperature room at 25℃ for 24 hours, it was subjected to a vulcanized rubber test to determine its hardness, tensile stress at break, and
TB (Kg/cm ² ), tensile elongation at break EB (%), and permanent elongation PS (%) were measured. Table 2 shows each result.
It was shown to. Each measurement method is as follows. Hardness: Six of the above sheets were stacked and measured using a type A tester according to the method described in JIS K6301 Physical Testing of Vulcanized Rubber Section 5.2 Spring Type Hardness Test. TB and EB: A No. 3 dumbbell test piece specified in JIS K6301 was punched out from the sheet, and the test piece was subjected to TB at a tensile speed of 500 mm/min at 25°C according to the method specified in JIS Section 3. and EB were measured.

[Table] Rufid

[Table] Example 6, Comparative Examples 4, 5, 6 Ethylene/α-olefin/5-ethylidene-2-norbornene copolymer rubber listed in Table 3, zinc white, vulcanization accelerator, stearic acid, sulfur, and light carbonic acid 10 calcium each in the proportions listed in Table 3.
Roll surface temperature 80℃ due to inch open roll
The mixture was kneaded for 20 minutes to prepare 1000 g of unvulcanized rubber compound. This compounded rubber was left at room temperature for 24 hours, then heated and vulcanized for 30 minutes using a heat press heated to 160°C to produce a sheet of 130 mm x 110 mm x 2 mm, and left in a constant temperature room at 25° C for 24 hours. Thereafter, the same vulcanized rubber test as in Example 1 was conducted. The results are shown in Table 3.

【table】

[Table] As is clear from the physical property values shown in the above examples, the properties of the vulcanized rubber of the present invention are as follows:
It is found that it is extremely suitable for use as automobile exterior parts such as bumper fillers, bumper rub strips, bumper side guards, overriders, and side protection moldings.

Claims (1)

[Claims] 1. The molar ratio of ethylene units to α-olefin units having 4 to 10 carbon atoms (ethylene/α-olefin) is 80/20 to 95/5, and the intrinsic viscosity [η] is
Consisting of 0.6 to 6.0 dl/g of ethylene, 100 parts by weight of α-olefin copolymer rubber, X parts by weight of a softener, Y parts by weight of a filler, and a vulcanizing agent, and 0≦X+Y≦300 and 0≦X≦75 A rubber composition for automobile exterior parts that satisfies the following. 2. The composition according to item 1, wherein the ethylene/α-olefin copolymer rubber has a molar ratio of ethylene units to α-olefin units (ethylene/α-olefin) of 83/17 to 95/5. . 3. The composition according to item 1 or 2, wherein the ethylene/α-olefin copolymer rubber has an intrinsic viscosity [η] of 0.8 to 4.0 dl/g. 4. The composition according to items 1 to 3, wherein the ethylene/α-olefin copolymer rubber contains a polyene component with an iodine value of 4 to 50. 5. The composition according to items 1 to 4, wherein the α-olefin is 1-butene. 6. The composition according to items 1 to 5, wherein the vulcanizate has a JISA hardness of 65 or more and a tensile stress at break of 70 Kg/cm ² or more. 7. The composition according to items 1 to 6, wherein the automobile exterior part is a bumper, a bumper filler, a bumper rub strip, a bumper side guard, an overrider, or a side protection molding.