JPH0912783A - Matte exterior automotive trim material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an exterior automotive trim material, excellent in vulcanizing properties such as mechanical strength and appearance and having a low surface glossiness and a uniform matte surface even if the trim is a vulcanized rubber molding prepared by mold forming such as compression, casting or injection molding. SOLUTION: This matte exterior automotive trim material comprises a vulcanized rubber molding prepared by vulcanization molding a rubber composition. The rubber composition contains (A) 100 pts.wt. at least one rubber selected from natural rubber and synthetic rubbers and (B) 5-80 pts.wt. synthetic resin. The synthetic resin (B) has (i) >=120 deg.C melting point measured according to differential scanning colorimetry (DSC), (ii) >=300,000 viscosity-average molecular weight and (iii) 1-50μm average particle diameter. The trim material can be used for applications such as weather strips or door glass runs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matte automobile exterior material having a low surface gloss (gloss) and comprising a vulcanized rubber molding having a so-called matte surface and having an excellent appearance.

[0002]

BACKGROUND OF THE INVENTION In automobiles, many rubber parts are used for various purposes other than tires. These rubber parts for automobiles are classified into parts such as anti-vibration rubber, belts and hoses, which are difficult to see on a daily basis, and parts which are easily noticed, such as glass run channels and weather strips.
Of these, parts such as weather strips are required to have an excellent function of blocking water, dust, and noise from the outside of the vehicle, but in recent years, high appearance design has also been desired. It was

Taking a weatherstrip as an example, this part is obtained by extruding a straight portion of the weatherstrip and
Since the connection part and the terminal part are vulcanized and bonded by molding such as compression molding, injection molding, and injection molding, the parts having different molding methods have different textures. That is, there is a problem that the surface of the extruded straight part of the weather strip has a low gloss and the surface of the molded part has a high gloss.

Therefore, in order to improve the appearance of the weather strip, the surface glossiness of the extruded portion is increased to the same surface glossiness as that of the die formed portion, or the surface glossiness of the die formed portion is lowered. It is then necessary to have the same surface gloss as that of the extruded part.

Conventionally, as a rubber compounding recipe for increasing the surface glossiness of the extruded part, there is a composition in which carbon black having a small particle size and a high structure is compounded. However, there is a problem that the surface gloss of the extruded part obtained from the rubber composition according to this formulation decreases with time due to bleeding or the like.

Next, as a method of lowering the surface glossiness of the molding portion, there is a method of matte-finishing the surface of the mold to make it matte. However, in the molding, when the matting mold is repeatedly used, the surface of the mold gradually becomes smooth due to contamination, and when it is transferred, the surface of the obtained molded part becomes smooth. Therefore, when polishing is performed to clean the mold surface, the product dimensions may not match, or it may not be possible to obtain the same matte surface as the original one. In addition, when the surface of the mold forming part is matted by secondary processing such as scraping the surface of the mold forming part or immersing it in a highly corrosive solvent to roughen the surface of the mold forming part, the process is There is a problem that it becomes complicated.

Therefore, even in the case of molding, by developing a rubber composition capable of providing a vulcanized rubber molded product having a low surface gloss and a uniform matte surface, a low surface gloss can be obtained. It has been desired to introduce a matte automobile exterior material having an excellent appearance, which is composed of a vulcanized rubber molded body prepared by molding having a uniform matte surface.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and is excellent in vulcanization physical properties such as mechanical strength characteristics, and further, compression molding, injection molding,
With the object of providing a matte automobile exterior material having a low surface gloss, a uniform matte surface, and an excellent appearance even in a vulcanized rubber molded body prepared by molding such as injection molding. There is.

[0009]

SUMMARY OF THE INVENTION A matte automobile exterior material according to the present invention is an automobile exterior material comprising a vulcanized rubber molded body obtained by vulcanizing and molding a rubber composition, wherein the rubber composition is [I] natural rubber and synthetic material. 100 parts by weight of at least one kind of rubber (A) selected from rubber and 5 to 80 parts by weight of [II] synthetic resin (B), the synthetic resin (B) is (i) measured by DSC. The melting point is 120 ° C. or higher, and (ii) the viscosity average molecular weight is 30.
50,000 or more, and (iii) the average particle size is 1 to 50
It is characterized in that it is μm.

In the above rubber composition, the rubber (A) and the synthetic resin (B) are mixed at a temperature lower than the melting point of the synthetic resin (B). The vulcanized rubber molded body to be a matte automobile exterior material according to the present invention is obtained by vulcanizing the above rubber composition at a temperature equal to or higher than the melting point of the synthetic resin (B), and has a surface gloss of 40% or less. .

The matte automobile exterior material according to the present invention is mainly a vulcanized rubber molding obtained by mold vulcanization molding (compression molding, injection molding, injection molding) of the above rubber composition.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The matte automobile exterior material according to the present invention will be specifically described below. The matte automobile exterior material according to the present invention comprises a vulcanized rubber molded body formed of the following rubber composition.

The rubber composition used in the present invention comprises at least one rubber (A) selected from natural rubber and synthetic rubber, and a synthetic resin (B). Rubber (A) The rubber (A) used in the present invention is a natural rubber (NR) and a synthetic rubber.

Specific examples of the synthetic rubber include polyisoprene rubber and styrene-butadiene copolymer rubber (SB
R), butadiene rubber (BR), chloroprene rubber, isoprene / isobutylene copolymer rubber, acrylonitrile / butadiene copolymer rubber, ethylene / propylene copolymer rubber (EPR), ethylene / propylene / diene copolymer rubber (EPDM) ), Acrylic rubber, urethane rubber, silicone rubber, fluororubber, and modified rubbers thereof, chlorosulfonated polyethylene, halogenated polyethylene and the like.

Of these, polyolefin-based rubbers such as EPR and EPDM are preferably used for applications of exterior materials requiring weather resistance. Synthetic Resin (B) Specific examples of the synthetic resin (B) used in the present invention include polyolefins such as polyethylene, polypropylene, polybutene-1, poly-4-phenylbutene-1; polyvinyl methyl ether, polyvinyl isobutyl ether. And the like; polyamides such as nylon-12 and nylon-7, and the like. Of these, polyethylene and polypropylene are preferably used.

The synthetic resin (B) used in the present invention is D
The melting point measured by SC (Differential Scanning Calorimeter) is 120 ° C. or higher. A synthetic resin having a melting point of less than 120 ° C. melts when mixed using a practical kneader such as a Banbury mixer, and there is a risk that the compounded rubber cannot be processed after being cooled. Further, the vulcanized rubber molded body obtained by using the synthetic resin having a melting point of less than 120 ° C. has deteriorated properties at high temperature, for example, thermal characteristics such as increased compression set. Therefore, in the present invention, a synthetic resin having a melting point lower than the temperature for vulcanization at a temperature of 120 ° C. or higher is used.

The synthetic resin (B) used in the present invention has an average molecular weight (viscosity average molecular weight) of 300,000 or more, preferably 50 by the viscosity method (ASTM D2857).
50,000 or more, more preferably 1,000,000
That is all.

By using such an ultrahigh molecular weight synthetic resin, a uniform surface state can be obtained without flattening or flowing of the synthetic resin in the flow direction of the compounded rubber during vulcanization. Therefore, the higher the molecular weight of the synthetic resin, the more preferable.

Further, the synthetic resin (B) used in the present invention
The Coulter Multisizer II (Coulter Electron
ics, manufactured by Inc.) having an average particle size of 1 to 50 μm.
m, preferably 1-40 μm, more preferably 1-3
5 μm.

By using the synthetic resin (B) having such an average particle diameter, the unevenness of the surface of the vulcanized rubber molded product becomes fine and an excellent matte state can be obtained.
In the present invention, the synthetic resin (B) is the rubber (A) 10
5 to 80 parts by weight, preferably 10 to 0 parts by weight
70 parts by weight, more preferably 20 to 60 parts by weight.

If the amount of the synthetic resin (B) mixed and dispersed in the rubber (A) is less than 5 parts by weight, a vulcanized rubber molding having a matte surface cannot be obtained. Further, if the amount of the synthetic resin (B) exceeds 80 parts by weight, the processability of the compounded rubber (unvulcanized) and the mechanical properties of the vulcanized rubber molded product are deteriorated, which is not preferable.

Other Components The rubber composition used in the present invention contains a rubber (A) and a synthetic resin (B) depending on the intended use and performance of the vulcanizate.
In addition, rubber reinforcing agents, fillers, types of softening agents and their amounts, vulcanizing agents, vulcanization accelerators, types of compounds constituting the vulcanization system such as vulcanization aids and their amounts, Type of anti-aging agent, processing aid and its compounding amount, and if necessary, type and compounding amount of compound for foaming such as foaming agent, foaming auxiliary agent, defoaming agent, and step of producing vulcanized product Can be appropriately selected.

The total amount of the rubber (A) and the synthetic resin (B) in the vulcanized product can be appropriately selected depending on the intended performance of the vulcanized product and the intended use, but is usually 20% by weight or more, preferably 25% by weight. It is more than weight%. [Rubber Reinforcing Agent and Filler] The rubber reinforcing agent has an effect of enhancing mechanical properties such as tensile strength, tear strength, and abrasion resistance of the vulcanized rubber.

Specific examples of such a rubber reinforcing agent include SRF, GPF, FEF, MAF, HAF and ISA.
Carbon blacks such as F, SAF, FT and MT, these carbon blacks that have been surface-treated with a silane coupling agent, silica, activated calcium carbonate,
Examples include fine powder talc and fine powder silicic acid.

The above-mentioned filler is used for the purpose of increasing the hardness of the rubber product and reducing the cost without affecting the physical properties so much. Specific examples of such a filler include light calcium carbonate, heavy calcium carbonate, talc, clay and the like.

The types and blending amounts of these rubber reinforcing agents and fillers can be appropriately selected depending on the intended use, but these blending amounts are usually up to 300 parts by weight, relative to 100 parts by weight of rubber (A), It is preferably up to 200 parts by weight. [Softening Agent] As the softening agent, a softening agent usually used for rubber can be used.

Specifically, petroleum-based softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, and petrolatum; coal tar-based softeners such as coal tar and coal tar pitch; castor oil, linseed oil, Fat oil softeners such as rapeseed oil and 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, zinc laurate; synthetic polymers such as petroleum resin, atactic polypropylene and coumarone indene resin A substance etc. can be mentioned. Among them, a petroleum softener is preferably used, and particularly, a process oil is preferably used.

The blending amount of these softening agents can be appropriately selected depending on the use of the vulcanized product, but the blending amount is usually 150 parts by weight at the maximum, preferably 100 parts by weight at most with respect to 100 parts by weight of the rubber (A). Parts by weight. [Vulcanizing Agent, Vulcanization Accelerator, and Vulcanization Aid] When the rubber composition used in the present invention is vulcanized, a vulcanizing agent is added to the rubber composition.

Vulcanizing agents include sulfur, sulfur compounds and organic peroxides. Specific examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur and the like.

Specific examples of the sulfur compound include sulfur chloride, sulfur dichloride, and polymer polysulfide. Further, it is also possible to use a sulfur compound which releases active sulfur at the vulcanization temperature and vulcanizes, such as morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, and selenium dimethyldithiocarbamate. You can Of these, sulfur is preferably used.

Sulfur or sulfur compounds are rubber (A)
It is used in a proportion of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight. Further, when sulfur or a sulfur compound is used as a vulcanizing agent, it is preferable to use a vulcanization accelerator together.

Specific examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazole sulfenamide and N-
Sulfenamide compounds such as oxydiethylene-2-benzothiazole sulfenamide and N, N-diisopropyl-2-benzothiazole sulfenamide; 2-mercaptobenzothiazole, 2- (2 ', 4'-dinitrophenyl) Thiazole compounds such as mercaptobenzothiazole, 2- (4'-morpholinodithio) benzothiazole and dibenzothiazyl disulfide; diphenylguanidine, diorthotolylguanidine, diorsonitrile guanidine,
Guanidine compounds such as orthonitrile biguanide, diphenylguanidine phthalate; acetaldehyde-
Aniline reaction product, butyraldehyde-aniline condensate,
Aldehydeamines such as hexamethylenetetramine and acetaldehyde ammonia, or aldehyde-ammonia compounds; imidazoline compounds such as 2-mercaptoimidazoline; thiourea compounds such as thiocarbanilide, diethylthiourea, dibutylthiourea, trimethylthiourea, and diorthotolylthiourea. Compounds; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide, and other thiuram compounds; zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate,
Zinc di-n-butyldithiocarbamate, zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate,
Examples thereof include dithioate-based compounds such as selenium dimethyldithiocarbamate and tellurium dimethyldithiocarbamate; xanthate-based compounds such as zinc dibutylxanthate; compounds such as zinc white.

These vulcanization accelerators are rubber (A) 100
0.1 to 20 parts by weight, preferably 0.
It is used in a proportion of 2 to 10 parts by weight. The organic peroxide may be any one commonly used for peroxide vulcanization of rubber. Specifically, dicumyl peroxide, di-t-
Butyl peroxide, di-t-butyl peroxy-3,3,5
-Trimethylcyclohexane, t-butyl hydroperoxide, t-butylcumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxine) 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-butylperoxide and di-t-butylperoxy-3,3,5-trimethylcyclohexane are preferably used. These organic peroxides are used alone or in combination of two or more.

The organic peroxide is 0.0003 to 0.05 mol, preferably 0.0 to 100 g of the rubber (A).
It is used in a proportion of 01 to 0.03 mol, but it is desirable to appropriately determine the optimum amount according to the required physical property values.

When an organic peroxide is used as a vulcanizing agent, it is preferable to use a vulcanizing auxiliary together. Specific examples of the vulcanization aid include sulfur; quinone dioxime compounds such as p-quinone dioxime; methacrylate compounds such as polyethylene glycol dimethacrylate; allyl compounds such as diallyl phthalate and triallyl cyanurate; Other maleimide compounds include divinylbenzene.

Such a vulcanization aid is used in an amount of 0.5 to 2 moles, preferably about equimolar, relative to 1 mole of the organic peroxide used. [Anti-aging agent] If an anti-aging agent is used, the material life can be further extended. This is the same as in the case of normal rubber.

The antiaging agent used in the present invention includes
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- Butyl-4'-hydroxyphenyl) propionate] methane and other phenolic stabilizers; bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-t-butylphenyl] sulfide and other thioether stabilizers Benzimidazole stabilizers such as 2-mercaptobenzimidazole; dithiocarbamate stabilizers such as nickel dibutyldithiocarbamate; quinoline stabilizers such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline And so on. These antioxidants may be used alone or in combination of two or more.

Such an antiaging agent is used as the rubber (A) 10
It is used in an amount of 5 parts by weight or less, preferably 3 parts by weight or less with respect to 0 parts by weight, and it is desirable to appropriately determine the optimum amount according to the required physical property values. [Processing Aid] As the above-mentioned processing aid, compounds used in ordinary processing of rubber can be used. Specifically, higher fatty acids such as ricinoleic acid, stearic acid, palmitic acid and lauric acid, higher fatty acid salts such as barium stearate, zinc stearate and calcium stearate, ricinoleic acid ester, stearic acid ester, palmitic acid ester and lauric acid. Examples include higher fatty acid esters such as acid esters.

Such a processing aid is usually rubber (A) 1
It is used in an amount of 10 parts by weight or less, preferably 5 parts by weight or less with respect to 00 parts by weight, but it is desirable to appropriately determine an optimal amount according to required physical properties. [Foaming Agent and Foaming Aid] The rubber composition according to the present invention is
As described above, it can be obtained by blending a foaming agent and a foaming auxiliary agent that are usually used in rubber, if necessary, and molding, foaming, and vulcanizing.

Specific examples of the foaming agent include inorganic foaming agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate and ammonium nitrite; N, N '.
-Dimethyl-N, N'-dinitrosoterephthalamide, N, N'-
Nitroso compounds such as dinitrosopentamethylenetetramine; azo compounds such as azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene, barium azodicarboxylate;
Benzylsulfonylhydrazide, toluenesulfonylhydrazide, p, p'-oxybis (benzenesulfonylhydrazide), diphenylsulfone-3,3'-disulfonylhydrazide and other sulfonylhydrazide compounds; calcium azide, 4,4-diphenyldisulfonylazide, p -Azide compounds such as toluene sulphonyl azide and the like can be mentioned.

These foaming agents are used in an amount of 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the rubber (A).
Used in parts by weight. If necessary, the foaming auxiliary agent used in combination with the foaming agent acts to lower the decomposition temperature of the foaming agent, promote decomposition, uniformize bubbles, and the like. Examples of such a foaming aid include organic acids such as salicylic acid, phthalic acid, stearic acid and oxalic acid, urea and derivatives thereof.

These foaming aids are added in an amount of 0.01 to 10 parts by weight, preferably 0.1% by weight, based on 100 parts by weight of the rubber (A).
It is used in a proportion of 1 to 5 parts by weight, but it is desirable to appropriately determine the optimum amount according to the required physical property values. [Defoaming agent] When vulcanizing the compounded rubber, bubbles may be formed or the degree of foaming may be different due to the water content. In order to prevent these, calcium oxide may be added as a defoaming agent.

Such a defoaming agent is usually used in the rubber (A) 10
It is used in a proportion of 20 parts by weight or less, preferably 10 parts by weight or less with respect to 0 parts by weight, but it is desirable to appropriately determine the optimum amount according to the required physical property values.

Preparation of Rubber Composition The rubber composition used in the present invention comprises a rubber (A), a synthetic resin (B) and the above-mentioned vulcanizing agent, vulcanization accelerator and vulcanization aid which are optionally used. , A rubber reinforcing agent, a filler, a softening agent, an antiaging agent, a processing aid, a foaming agent, a foaming aid, a defoaming agent and the like, can be prepared by a general method for preparing a rubber compound. it can.

In the present invention, the synthetic resin (B) is mixed and dispersed at a temperature lower than its melting point, that is, the synthetic resin (B) is dispersed in the compounded rubber without forming a continuous phase. is important.

When the synthetic resin (B) is mixed with the rubber (A) at a temperature above the melting point, the synthetic resin (B) forms a continuous phase or is compatible with the rubber (A), and as a result, once. The viscosity of the compounded rubber cooled to the melting point or less increases remarkably. Therefore, this compounded rubber becomes difficult to roll at a temperature below the melting point, that is, below 120 ° C.,
It becomes impossible to actually mold it.

Therefore, the rubber composition (unvulcanized compounded rubber) used in the present invention is prepared, for example, by the following method. That is, rubber (A) and additives such as a filler and a softening agent are kneaded at a temperature of 80 to 170 ° C. for 3 to 10 minutes with an internal mixer such as a Banbury mixer, a kneader, and an intermix, and then an open roll is used. Using a roll such as the above or a kneader, the synthetic resin (B), the vulcanizing agent, and if necessary, the vulcanization accelerator or vulcanization aid and the foaming agent are additionally mixed at a temperature of less than 120 ° C. It can be prepared by kneading at a roll temperature of 40 to 80 ° C. for 5 to 30 minutes and then dispensing.

When the kneading temperature in the internal mixer is low, the synthetic resin (B), the vulcanizing agent, the vulcanization accelerator, the foaming agent and the like are simultaneously kneaded together with the polymer, the filler, the softening agent and the like. May be.

Automotive Exterior Materials (Vulcanized Rubber Molded Articles) The matte automotive exterior materials (vulcanized rubber molded articles) according to the present invention can be prepared from the above-mentioned rubber composition at the time of normally vulcanizing general rubber. Similarly, an unvulcanized compounded rubber may be once prepared by the method described above, and then the compounded rubber may be molded into an intended shape and then vulcanized.

The unvulcanized compounded rubber prepared as described above can be molded and vulcanized by various molding methods. Molds such as compression molding (press molding), injection molding and injection molding can be used. By molding, the characteristics can be most exerted when molding and vulcanizing.

That is, in the case of compression molding, a pre-weighed unvulcanized compounded rubber is put into a mold, and after the mold is closed, 120 to 2
By heating at a temperature of 70 ° C. for 30 seconds to 120 minutes, the target vulcanized rubber molded body can be obtained.

In the case of injection molding, pre-weighed unvulcanized compounded rubber is put in a pot and put in a mold by a piston for 1 to 20 minutes.
Inject in seconds. After injection, at a temperature of 120-270 ° C., 30
The desired vulcanized rubber molded product is obtained by heating for seconds to 120 minutes.

In the case of injection molding, a ribbon-shaped or pellet-shaped compounded rubber is fed to the pot by a screw in a preset amount. Subsequently, the preheated compounded rubber is fed into the mold by a plunger in 1 to 20 seconds and heated in the same manner as in the above injection molding to obtain the desired vulcanized rubber molded body.

In the present invention, in the case of these mold moldings, the synthetic resin (B) is melted during the vulcanization to give the rubber (A).
The volume expansion becomes larger than that of the other compounding agents and it is important to return to the original volume when cooled after molding.

The vulcanized rubber molded product prepared as described above, that is, the matte automobile exterior material according to the present invention, has a surface gloss of 40% or less. A method for measuring this surface gloss will be described later in Examples.

[0056]

The matte automobile exterior material according to the present invention is a vulcanized rubber molding obtained by vulcanizing and molding a rubber composition containing a rubber (A) and a specific synthetic resin (B) in a specific ratio. As it consists of a body, it has excellent vulcanization properties such as mechanical strength.
Even a vulcanized rubber molded body prepared by mold molding such as compression molding, transfer molding, and injection molding has a uniform matte surface with low surface gloss and is excellent in appearance.

The matte automobile exterior material according to the present invention having the above effects can be used for weather strips, door grass runs and the like. In particular, it can be suitably used for these molding applications, for example, corner strips and end portions of weather strips, door glass runs, and the like.

The present invention will be described below with reference to examples.
The present invention is not limited to these examples. The synthetic resins used in the examples are shown in Table 1.

The tensile test, hardness test, compression set test and gloss measurement test performed on the vulcanizates obtained in Examples and Comparative Examples are as follows. (Test Method) (1) Tensile Test A test piece was obtained by punching a vulcanized rubber sheet having a length of 135 mm, a width of 120 mm and a thickness of 2 mm with a No. 3 type dumbbell described in JIS K6301 (1989).

Using this test piece, the same JIS K 6301 was used.
According to the method specified in Section 3, the measurement temperature is 25 ° C,
A tensile test was carried out under the condition of a tensile speed of 500 mm / min to measure the stress at tensile break (T _B ) and the elongation at tensile break (E _B ). (2) Hardness test In the hardness test, six vulcanized rubber sheets each having a thickness of 2 mm are stacked,
The spring hardness HS (JIS-A hardness) was measured according to JIS K 6301 (1989). (3) Compression set test A vulcanized rubber block having a diameter of 29 mm and a height of 12.7 mm was attached to a compression device according to the method described in JIS K 6301 (1989) Item 10, and the test piece height was increased. Was compressed to 3/4 of the height before applying a load, and the whole mold was heat-treated in a gear oven at 70 ° C. for 22 hours.

After the heat treatment, the test piece was taken out of the compression apparatus and allowed to cool for 30 minutes, the height of the test piece was measured, and the compression set was calculated by the following formula. Compression set [%] = [(t _O −t ₁ ) / (t _O −
t ₂ )] × 100 t _O : Height of the test piece before the test t ₁ : Height after heat treatment of the test piece and allowing it to cool for 30 minutes t ₂ : Height of the test piece attached to the measurement mold (4) Gloss measurement test The surface glossiness of the vulcanized rubber is measured by a gloss meter [gloss checker IG-310, incident angle 60 °, light reception angle 60 °:
HORIBA, Ltd.] was applied to the surface of the vulcanized rubber sheet for measurement.

[0062]

[Comparative Example 1] Ethylene / propylene / 5-ethylidene-2-
Norbornene terpolymer [trade name: Mitsui EPT402
1, Mitsui Petrochemical Industry Co., Ltd.] 100 parts by weight, zinc white 5 parts by weight, stearic acid 1 part by weight, polyethylene glycol # 4000 1 part by weight, FEF carbon black [trade name: Seast SO, Tokai] 65 parts by weight of Carbon Co., Ltd. and 40 parts by weight of paraffin-based process oil [trade name: Diana Process PW-380, manufactured by Idemitsu Kosan Co., Ltd.] were kneaded with a Banbury mixer of 1.7 liter capacity for 5 minutes. .

Furthermore, after wrapping this composition on an 8-inch roll having a surface temperature of 50 ° C., 212 parts by weight of this composition was used to prepare N-cyclohexyl-2-benzothiazolylsulfenamide [trade name: Sancellar CM]. , Sanshin Chemical Industry Co., Ltd., vulcanization accelerator] 1.5 parts by weight, zinc dimethyldithiocarbamate [trade name: Sancella PZ, Sanshin Chemical Industry Co., Ltd., vulcanization accelerator] 0.2 parts by weight Part, zinc di-n-butyldithiocarbamate [Product name: Sancellar BZ,
Sanshin Chemical Industry Co., Ltd., vulcanization accelerator] 0.5 parts by weight, sulfur [vulcanization agent] 2.0 parts by weight, and defoaming agent [trade name:
Vestar 18, manufactured by Inoue Lime Co., Ltd.] 4 parts by weight were added and kneaded for 8 minutes, and the resulting mixture was allowed to cool.

From this blend, using a press molding machine, 18
Vulcanization was performed at 0 ° C. for 5 minutes to prepare a rubber sheet having a thickness of 2 mm. Also, the rubber block for compression set test,
It was prepared by vulcanizing at 180 degrees for 10 minutes.

The vulcanized product obtained as described above was subjected to a tensile test, a hardness test, a compression set test and a gloss measurement test by the above methods. Table 2 shows the results.

[0066]

Example 1 In Comparative Example 1, before adding the vulcanizing agent and the vulcanization accelerator, polyethylene [melting point: 136 ° C., viscosity average molecular weight: 1,700,000, average particle diameter: 30 μm, synthetic resin (1)] ] The same procedure as in Comparative Example 1 was repeated except that 20 parts by weight of a roll was added.

The results are shown in Table 2. Next, the unvulcanized rubber compound shown in Table 2 obtained in Example 1 was molded and vulcanized by a known method (injection molding) to prepare an automobile exterior material. As a result, a matte automobile exterior material was obtained.

[0068]

Example 2 The procedure of Example 1 was repeated, except that the addition amount of the synthetic resin (1) was changed to 40 parts by weight.

The results are shown in Table 2. Next, the unvulcanized rubber compound shown in Table 2 obtained in Example 2 was molded and vulcanized by a known method (injection molding) to prepare an automobile exterior material. As a result, a matte automobile exterior material was obtained.

[0070]

Comparative Example 2 In Comparative Example 1, the synthetic resin (1) was added with a Banbury mixer and kneaded in the same manner as in Comparative Example 1 to obtain 1
The 45 ° C. formulation was discharged. This compound has a surface temperature of 5
It was wrapped around an 8 inch roll at 0 ° C., but as the formulation cooled, it set rapidly and could not be rolled.

[0071]

Example 3 In Example 2, instead of the synthetic resin (1), polyethylene [melting point: 136 ° C., viscosity average molecular weight:
1,800,000, average particle diameter: 25 μm, and the same procedure as in Example 2 was performed except that the synthetic resin (2) was used.

The results are shown in Table 2. Next, the unvulcanized rubber compound shown in Table 2 obtained in Example 3 was used for molding and vulcanization by a known method (injection molding) to prepare an automobile exterior material. As a result, a matte automobile exterior material was obtained.

[0073]

Comparative Example 3 In Example 2, instead of the synthetic resin (1), polyethylene [melting point: 136 ° C., viscosity average molecular weight:
The same procedure as in Example 2 was performed except that the synthetic resin (3)] was used.

The results are shown in Table 2.

[0075]

Example 4 Polypropylene [melting point: 156 ° C., viscosity average molecular weight: 450,000, average particle size: 36 μm, synthetic resin (4)] was used in place of synthetic resin (1) in Example 2. The same procedure as in Example 2 was performed.

The results are shown in Table 2. Next, the unvulcanized rubber compound shown in Table 2 obtained in Example 4 was molded and vulcanized by a known method (injection molding) to prepare an automobile exterior material. As a result, a matte automobile exterior material was obtained.

[0077]

[Table 1]

[0078]

[Table 2]

From the results shown in Table 2, it is understood that when the synthetic resin is added at a temperature lower than the melting point and vulcanized, the surface gloss of the rubber sheet is reduced without lowering the tensile strength (Examples 1 to 4). ).

Further, when the synthetic resin is kneaded at a temperature equal to or higher than the melting point, the workability is poor, and when the particle size of the synthetic resin is large, the effect of reducing the gloss is small (Comparative Example 2,
3).

[0081]

Comparative Example 4 100 parts by weight of styrene-butadiene rubber [trade name: Nippon Pole 1502, manufactured by Nippon Zeon Co., Ltd.], 5 parts by weight of zinc white, 1 part by weight of stearic acid,
80 parts by weight of FEF carbon black [Product name: Asahi # 60G, manufactured by Asahi Carbon Co., Ltd.] and naphthene-based process oil [Product name: Sansen 4240, Nippon San Oil Co., Ltd.]
60 parts by weight and phenyl-1-naphthylamine [trade name: Nocrac PA, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.]
5 parts by weight were kneaded with a 1.7 liter Banbury mixer for 5 minutes.

Further, after wrapping the composition on an 8-inch roll having a surface temperature of 50 ° C., the composition 247.5
1.2 parts by weight of dibenzothiazyl disulfide [trade name: Sancellar DM, manufactured by Sanshin Chemical Industry Co., Ltd., vulcanization accelerator], N, N'-di-o-tolylguanidine [trade name] : Sancella DT, manufactured by Sanshin Chemical Industry Co., Ltd., vulcanization accelerator] 0.2 parts by weight, and sulfur [vulcanization agent] 1.
75 parts by weight were added and kneaded for 8 minutes, and the obtained compound was allowed to cool.

From this blend, using a press molding machine, 16
Vulcanization was performed at 0 ° C. for 20 minutes to prepare a rubber sheet having a thickness of 2 mm. A rubber block for compression set test was prepared by vulcanizing at 160 degrees for 30 minutes.

The vulcanizates obtained as described above were subjected to a tensile test, a hardness test, a compression set test and a gloss measurement test by the above methods. Table 3 shows the results.

[0085]

Example 5 The procedure of Comparative Example 1 was repeated except that 30 parts by weight of polyethylene [synthetic resin (1)] was added by a roll before adding the vulcanizing agent and the vulcanization accelerator.

The results are shown in Table 3. Next, the unvulcanized rubber compound shown in Table 3 obtained in Example 5 was molded and vulcanized by a known method (transfer molding) to prepare an automobile exterior material. As a result, a matte automobile exterior material was obtained.

[0087]

Comparative Example 5 100 parts by weight of natural rubber (NR), 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, and FEF carbon black [trade name: Asahi # 60G, Asahi Carbon Co., Ltd.
50 parts by weight, naphthene-based process oil [Product name: Sansen 4240, manufactured by Nippon San Oil Co., Ltd.], 20 parts by weight, phenyl-1-naphthylamine [Product name: Nocrac PA, Ouchi Shinko Chemical Co., Ltd. 1) and 1 part by weight were kneaded with a 1.7 liter capacity Banbury mixer for 5 minutes.

Further, after wrapping this composition on an 8-inch roll having a surface temperature of 50 ° C., 177 parts by weight of this composition was treated with 2-mercaptobenzothiazole [trade name: Sancellar M, Sanshin Chemical Co., Ltd.]. Vulcanization accelerator manufactured by Kogyo Co., Ltd.]
7 parts by weight, N, N'-di-o-tolylguanidine [Product name: Sancellar DT, Sanshin Chemical Industry Co., Ltd., vulcanization accelerator]
0.1 parts by weight, tetramethylthiuram monosulfide [trade name: Sancellar TS, manufactured by Sanshin Chemical Industry Co., Ltd., vulcanization accelerator] 0.1 parts by weight, and sulfur [vulcanization agent] 2.
5 parts by weight was added and kneading was performed for 8 minutes, and the obtained compound was allowed to cool.

From this blend, using a press molding machine, 15
Vulcanization was performed at 0 ° C. for 20 minutes to prepare a rubber sheet having a thickness of 2 mm. A rubber block for a compression set test was prepared by vulcanizing at 150 ° C for 30 minutes.

The vulcanized product obtained as described above was subjected to a tensile test, a hardness test, a compression set test and a gloss measurement test by the above methods. Table 3 shows the results.

[0091]

Example 6 The procedure of Comparative Example 5 was repeated, except that 30 parts by weight of polyethylene [synthetic resin (1)] was added by a roll before adding the vulcanizing agent and the vulcanization accelerator.

The results are shown in Table 3. Next, the unvulcanized rubber compound shown in Table 3 obtained in Example 6 was molded and vulcanized by a known method (injection molding) to prepare an automobile exterior material. As a result, a matte automobile exterior material was obtained.

[0093]

[Comparative Example 6] Isoprene / isobutylene rubber [Product name:
Butyl 268, manufactured by Japan Synthetic Rubber Co., Ltd.] 100 parts by weight, zinc white 5 parts by weight, stearic acid 2 parts by weight,
HAF carbon black [Product name: Asahi # 70, manufactured by Asahi Carbon Co., Ltd.] 50 parts by weight, and naphthenic process oil [Product name: Sansen 4240, manufactured by Nippon San Oil Co., Ltd.]
25 parts by weight were kneaded with a 1.7 liter Banbury mixer for 5 minutes.

Furthermore, after wrapping this compound on an 8-inch roll having a surface temperature of 50 ° C., 181 parts by weight of this compound was mixed with dibenzothiazyl disulfide [trade name: Sancellar DM, Sanshin Chemical Industry Co., Ltd.]. Made, vulcanization accelerator]
1.0 part by weight, tellurium diethyldithiocarbamate [trade name: Sancella TE-G, manufactured by Sanshin Chemical Industry Co., Ltd.]
1.9 parts by weight and 1.5 parts by weight of sulfur [vulcanizing agent] were added, and the mixture was kneaded for 8 minutes, and the obtained compound was allowed to cool.

From this blend, using a press molding machine, 16
Vulcanization was performed at 0 ° C. for 20 minutes to prepare a rubber sheet having a thickness of 2 mm. A rubber block for compression set test was prepared by vulcanizing at 160 degrees for 30 minutes.

The vulcanized product obtained as described above was subjected to a tensile test, a hardness test, a compression set test and a gloss measurement test by the above methods. Table 3 shows the results.

[0097]

Example 7 The procedure of Comparative Example 6 was repeated, except that 30 parts by weight of polyethylene [synthetic resin (1)] was added by a roll before adding the vulcanizing agent and the vulcanization accelerator.

The results are shown in Table 3. Next, the unvulcanized rubber compound shown in Table 3 obtained in Example 7 was used for molding and vulcanization by a known method (injection molding) to prepare an automobile exterior material. As a result, a matte automobile exterior material was obtained.

[0099]

[Table 3]

From the results shown in Table 3, it can be seen that, when the synthetic resin is added at a temperature lower than the melting point and vulcanized at a temperature higher than the melting point, the gloss is lowered in various rubbers (Examples 5 to 5
7).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaneko Matsudaira 2-2-8, Shino-cho, Nishi-ku, Hiroshima City, Hiroshima Prefecture Nishikawa Rubber Industry Co., Ltd.

Claims (4)

[Claims] 1. An automobile exterior material comprising a vulcanized rubber molded body obtained by vulcanizing and molding a rubber composition, wherein the rubber composition is [I] at least one rubber (A) selected from natural rubber and synthetic rubber. ) 100 parts by weight and [II] synthetic resin (B) 5 to 80 parts by weight, the synthetic resin (B) has a melting point of 120 ° C. or higher (i) measured by DSC, ii) Viscosity average molecular weight is 30
50,000 or more, and (iii) the average particle size is 1 to 50
Matte automobile exterior material characterized by being μm. 2. The gloss according to claim 1, wherein the rubber composition is obtained by mixing the rubber (A) and the synthetic resin (B) at a temperature lower than the melting point of the synthetic resin (B). Erasing exterior material. 3. The vulcanized rubber molded body is obtained by vulcanizing a rubber composition at a temperature equal to or higher than the melting point of the synthetic resin (B) and has a surface gloss of 40% or less. Item 1
Or the matte automobile exterior material according to 2. 4. The rubber composition is molded by vulcanization molding (compression molding,
A matte automobile exterior material according to any one of claims 1 to 3, which is a vulcanized rubber molded body obtained by injection molding or injection molding.