JP3383030B2 - Resin automobile bumper - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin bumper made of resin having high rigidity and high impact resistance, which can be easily and easily coated. More specifically, the present invention relates to an automobile bumper made of an olefinic resin that exhibits excellent coating adhesion even if the surface treatment such as cleaning with a halogen-based organic solvent in the pretreatment step, primer coating, plasma treatment, etc. is not performed in coating. .

[0002]

2. Description of the Related Art Conventionally, when coating the surface of a resin automobile bumper, in a vapor of a halogen-based organic solvent in order to remove the hand marks, mold release agent, and rust inhibitor adhered to the bumper surface in the previous step. Exposed to and washed. Then, this cleaning not only fulfills its purpose, but also dissolves the low crystallinity portion of the bumper surface layer and the elastomer to form fine irregularities, and also serves an important function of improving the adhesion of the coating material.
In addition, since the olefin resin has no polar group in its structure and does not show adhesion with a paint having polarity, it is generally applied by applying a primer or by applying the surface polarity generated by plasma treatment. .

[0003]

The above-mentioned coating methods have their respective problems. That is, in coating an automobile bumper made of an olefin resin, the halogen-based organic solvent used in the cleaning step is regarded as a major factor that destroys the ozone layer by escaping to the atmosphere.
It is a decision that production and use will be abolished at the end of 5 years. Therefore, there is a sign that some water-based cleaning will be put to practical use as a representative of the next-generation cleaning process that is harmless to the environment and low in pollution, but material technology with sufficient paint adhesion is required even for such new methods. Has been. Further, in the method of applying a primer, the organic solvent in the primer escapes to the atmosphere and causes photochemical smog and the like, which poses the same environmental pollution problem as the halogen-based organic solvent. Therefore, there is also a need here for a material technology that does not require a primer and can directly and practically adhere the paint. Furthermore, the plasma treatment method is activated in a plasma atmosphere, and since the introduced polar groups and radicals reach a depth of several angstroms below the surface of the material, the activity will be lost due to handling, and it will not adhere to the molding die. Lubricating oils, mold release agents, etc. are detrimental factors for activation, which causes instability of the adhesion of the paint.
There is a problem with lack of credibility. Therefore, as an alternative, it is required to provide the material itself with an activity effective for the adhesion of the paint. As described above, the coating of resin-made automobile bumpers, whose material itself does not have coatability, is currently
Each has environmental and technical problems.

On the other hand, as a modification technique of an olefin resin capable of effectively adhering a coating material to the material itself, several techniques of graft modification with an unsaturated carboxylic acid or an anhydride thereof have been reported. For example, although there are many reports of graft-modifying an elastomer component, when the elastomer component is graft-modified to an amount within a range capable of exhibiting paint adhesion performance, a gel component is inevitably generated, and a molding obtained by molding this graft-modified composition is obtained. The surface of the body is not smooth, and the appearance of the painted surface is poor, which makes it unsuitable for the surface appearance of automobile bumpers. Furthermore, there arises a problem that the low temperature impact strength required for the bumper also decreases. The same applies when the resin component and the elastomer component are simultaneously graft-modified. There are also many reports of graft-modifying only the resin component.
In each of JP-A-76041 and JP-A-4-154850, a tackifying component is further required, and in this case, there is a problem in releasing a large-sized molding such as a bumper. Further, Japanese Patent Application Laid-Open No. 61-40345 discloses only the modifying effect of one kind of polyethylene. Furthermore, JP-A-48-20
824, JP-A-58-49736, JP-A-61-8.
The compositions disclosed in Japanese Patent No. 9239 and Japanese Patent Application Laid-Open No. 5-59231 have insufficient adhesion depending on the type of coating material, and the coating film can be easily formed even under a light collision required for a bumper. Since it peels off, there is still a problem in terms of reliability.

[0005]

[Means for Solving the Problems]

[Summary of the Invention] As a result of intensive studies conducted by the present inventors in view of the above problems, the use of a specific resin composition makes it possible to directly attach a coating material to an automobile bumper, and Molding workability that allows molding, rigidity (bending elasticity) that can be mounted on an automobile and withstand a light collision in practical use
With the knowledge that low temperature impact resistance (Izod impact) can be designed, the present invention has been completed. That is, the resin automobile bumper of the present invention, as a material component,
The following components (a), (b), (c), (d) and (e)
10 to 50% by weight of component (a), 2 to 20% by weight of component (b), 5 to 40% by weight of component (c), 20 to 40% by weight of component (d), and component (e) ) Is 15 to 25% by weight and the total amount of each component is 100% by weight, and the physical properties of the material are such that the bending elastic modulus is 1400 MPa or more at 23 ° C., and the Izod impact strength is 5 kJ / at 30 ° C. It is molded from an olefin resin composition having m ² or more and an MFR value of 5 g / 10 minutes or more. Component (a): 0.03 to 1.2% by weight of at least one compound selected from unsaturated carboxylic acids or their derivatives
Low-concentration modified olefin resin component (b) contained: High-concentration modified olefin resin component (c) containing 3 to 12% by weight of at least one compound selected from unsaturated carboxylic acids or derivatives thereof: unmodified olefin resin Resin component (d): Elastomer component (e): Filler

[Detailed Description of the Invention] [I] Olefin Resin Composition (1) Constituent Components The olefin resin composition used in the resin automobile bumper of the present invention comprises the following components (a) to (e). ) Is basically composed of. (a) Component (a): Low-concentration modified olefin resin Containing 0.03 to 1.2% by weight of at least one compound selected from unsaturated carboxylic acids and their derivatives used as the component (a) of the present invention. The low-concentration modified olefin-based resin (hereinafter, simply referred to as "low-concentration modified olefin-based resin") is an olefin-based resin in which at least one compound selected from unsaturated carboxylic acids and derivatives thereof is 0.03 to 1.2% by weight, preferably 0.06-1
Graft-copolymerized within the range of% by weight. When the graft amount is outside the above range, only the effect of the present invention is extremely low.

The olefin resin used here is an α-olefin represented by ethylene, propylene, butene-1,3-methylbutene-1, pentene-1,4-methylpentene-1, hexene-1 and the like. Examples thereof include a homopolymer, a mutual copolymer of these α-olefins, a copolymer of the above α-olefin and an organic silicon compound, or a graft polymer onto the olefin resin. These polymers have a flexural modulus of 1,000 to 30,0 measured according to JIS-K7203.
00 kg / cm ² , preferably 2,000 to 20,000
0 kg / cm ² , particularly preferably 3,000 to 15,0
It is the one of 00 kg / cm ² . The melt flow rate (MFR) of the polymer is not particularly limited, but the value measured according to ASTM-D1238 is usually 0.001 to 200 g / 10 minutes, preferably 0.01 to
Optimally, it is within the range of 100 g / 10 minutes. Examples of the olefin resin include polyethylene resins such as so-called low-pressure polyethylene, medium-pressure polyethylene, high-pressure polyethylene, and linear low-density polyethylene,
Stereoregular polypropylene, Stereoregular polybutene-
1, stereoregular poly α-, such as stereoregular poly 3-methylbutene-1 and stereoregular poly 4-methylpentene-1
An olefin resin can be mentioned. Among these olefin resins, stereoregular polypropylene (hereinafter simply referred to as "propylene resin") is preferable.

As the propylene resin, a propylene homopolymer or a propylene component is 70 mol%.
As described above, preferably a copolymer of propylene and the α-olefin consisting of 80 mol% or more and having a flexural modulus of elasticity of 3,000 to 25,000 kg / measured according to JIS-K7203. cm ^2, and preferably 8,000~20,000kg / cm ^2, particularly preferably those of 9,000~18,000kg / cm ^2. The melt flow rate (MFR) of the polymer is not particularly limited, but the value measured according to ASTM-D1238 is usually 0.001 to 50 g / 10.
Most preferably, it is within the range of 0.01 to 10 g / 10 min. Among these propylene-based resins, propylene homopolymers and propylene / ethylene copolymers are preferable, and propylene homopolymers and propylene / ethylene random copolymers are particularly preferable. These propylene-based resins can be used alone or as a mixture of a plurality of types of the above-mentioned resins, and usually, they can be appropriately selected and used from commercially available resins.

The unsaturated carboxylic acid or its derivative used here is acrylic acid, methacrylic acid, 3-butenoic acid, crotonic acid, pentenoic acid, heptenoic acid, octenoic acid, nonenoic acid, decenoic acid, undecenoic acid, maleic acid. Unsaturated carboxylic acids such as acids, itaconic acid, citraconic acid, tetrahydrophthalic acid, norbornene-5,6-dicarboxylic acid, or anhydrides and esters, amides, imides, metal salts, etc. of these unsaturated carboxylic acids Can be mentioned. Of these, acrylic acid, methacrylic acid, maleic acid, or their anhydrides and derivatives are preferable, and maleic anhydride is particularly preferable.

The method for producing the low-concentration modified olefin resin used as the component (a) of the present invention is not particularly limited. For example, at least one selected from the above-mentioned propylene resin and unsaturated carboxylic acid or its derivative. The compound (1) is produced by a method of producing a compound by graft-reacting with an organic peroxide in the presence of a suitable solvent or under heating and melting.

Organic Peroxides Specific examples of organic peroxides used in the production include di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide and 2,5-
Dialkyl peroxides such as dimethyl-2,5-bis (t-butylperoxy) hexane; acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, 2 , 4
-Diacyl peroxides such as dichlorobenzoyl peroxide; t-butyloxyacetate, t-butylperoxybutyrate, t-butylperoxy-2-
Ethyl hexanoate, t-butyl peroxylaurylate, t-butyl peroxybenzoate, di-t-butyl peroxyisophthalate, 2,5-dimethyl-
Peroxyesters such as 2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxydiisopropyl carbonate, cumylperoxyoctate; 1,1-bis (t
-Butylperoxy) -3,5,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, 2,2-bis (t -Butyl peroxy) butane and the like; and t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5
And hydroperoxides such as dimethyl-2,5-dihydroperoxide. Among these, diacyl peroxides and peroxyesters are preferable, and diacyl peroxides are particularly preferable. This organic peroxide is used in an amount of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, particularly preferably 0.1 to 1 part by weight, based on 100 parts by weight of the olefin resin. To be

A monomer copolymerizable with at least one compound selected from the above unsaturated carboxylic acids or their derivatives may be used in the low concentration modified olefin resin as long as the characteristics of the present invention are not impaired. It is possible. Specific examples include vinyl aromatic compounds such as styrene, α-methylstyrene and vinyltoluene; nitrile compounds such as acrylonitrile and methacrylonitrile; vinylpyridines such as 2-vinylpyridine and 4-vinylpyridine; methyl vinyl ether, 2- Vinyl ethers such as chloroethyl vinyl ether; vinyl halides such as vinyl chloride and vinyl bromide; halogenated vinyl such as nato; vinyl esters such as vinyl acetate.

(B) Component (b): Highly Concentrated Modified Olefin Resin Containing 3 to 12% by weight of at least one compound selected from the unsaturated carboxylic acids used as the component (b) of the present invention or derivatives thereof. The high-concentration modified olefin-based resin (hereinafter abbreviated as “high-concentration modified olefin-based resin”) is an olefin-based resin containing at least one compound selected from unsaturated carboxylic acids and derivatives thereof.
It is a graft-copolymerized within the range of -12 wt%, preferably 5-10 wt%. If the graft amount is outside the above range, the effect of the present invention is very low. The olefin resin used here may be the same as the above-mentioned component (a), but among these olefin resins, a propylene resin is preferable, and the melt flow (MFR) of the resin is ASTM.
The value measured according to -D1238 is usually 0.001 to
Optimally, it is within the range of 50 g / 10 minutes, preferably 0.01 to 10 g / 10 minutes. Among these propylene-based resins, propylene homopolymers and propylene-ethylene copolymers are preferable, and propylene homopolymers and propylene / ethylene random copolymers are particularly preferable. These propylene-based resins can be used alone or as a mixture of a plurality of types of the above-mentioned resins, and usually, they can be appropriately selected and used from commercially available resins.

The unsaturated carboxylic acid or its derivative used here is acrylic acid, methacrylic acid, 3-butenoic acid, crotonic acid, pentenoic acid, heptenoic acid, octenoic acid, nonenoic acid, decenoic acid, undecenoic acid, maleic acid. Unsaturated carboxylic acids such as acids, itaconic acid, citraconic acid, tetrahydrophthalic acid, norbornene-5,6-dicarboxylic acid, or anhydrides and esters, amides, imides, metal salts, etc. of these unsaturated carboxylic acids Can be mentioned. Of these, acrylic acid, methacrylic acid, maleic acid, or their anhydrides and derivatives are preferable, and maleic anhydride is particularly preferable.

The method for producing the high-concentration modified olefin resin used as the component (b) of the present invention is not particularly limited. For example, at least one selected from the above-mentioned propylene resin and unsaturated carboxylic acid or its derivative. A compound of the above, in the presence of a suitable solvent, or under heating and melting, a method of producing by grafting a combined use of an organic peroxide, the propylene-based resin is pyrolyzed, to the generated molecular terminal It is produced by a method of adding an unsaturated carboxylic acid, or at least one compound selected from an anhydride thereof and a derivative thereof, to a low molecular weight propylene resin having a double bond, using an azo radical initiator.

Specific examples of the above-mentioned organic peroxide used in the production include those similar to the above-mentioned organic peroxides. Among these, dialkyl peroxides, dialkyl peroxides and It is preferable to use peroxyesters, and it is particularly preferable to use dialkyl peroxides and peroxyesters. Further, specific examples of the azo radical initiator include azobisisobutyronitrile,
2,2′-azobis- (2-amidinopropane) dibasic acid, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2, 2'-azobis (4-methoxy-
2,4-dimethylvaleronitrile) and the like, preferably azobisisobutyronitrile and 1,1
′ -Azobis (cyclohexane-1-carbonitrile)
Is. The organic peroxide or azo radical initiator was added in an amount of 0.
01 to 20 parts by weight, preferably 0.05 to 15 parts by weight,
It is particularly preferably used in the range of 0.1 to 10 parts by weight.

It is also possible to use a monomer copolymerizable with at least one compound selected from the above-mentioned unsaturated carboxylic acids or their derivatives within the range that does not impair the characteristics of the present invention, as the highly concentrated modified olefin resin. Is.
Specific examples thereof include the same as the above-mentioned monomers.

(C) Component (c): unmodified olefin resin The unmodified olefin resin used here may be the same as the olefin resin used in the above component (a), but this olefin Among the resins, a propylene resin is preferable, and the melt flow rate (MFR) of the resin is usually 0.01 to 200 g / 10 minutes, preferably 0.1, as measured according to ASTM-D1238. Optimal is in the range of up to 100 g / 10 minutes. Further, among these unmodified propylene-based resins,
A copolymer of propylene and another α-olefin is preferable, and a copolymer of ethylene is particularly preferable. The copolymer may be a random copolymer or a block copolymer, but a block copolymer is particularly preferable.

(D) Component (d): Elastomer The elastomer used as the component (d) of the present invention is a polymer that exhibits rubber elasticity at room temperature and is selected from natural rubber and synthetic rubber. Specific examples of the synthetic rubber include styrene elastomer, butadiene rubber, isoprene rubber, olefin elastomer, acrylonitrile / butadiene copolymer rubber, chloroprene rubber, butyl rubber, urethane elastomer, silicone elastomer, fluorine elastomer and acrylic elastomer. Is mentioned. Among these, styrene-based elastomers and olefin-based elastomers, urethane-based elastomers, silicon-based elastomers, and acrylic-based elastomers are preferable, and styrene-based elastomers and olefin-based elastomers are particularly preferable, and specific examples thereof are shown below.

Styrenic Elastomer Examples of the styrenic elastomer include styrene and α-
An elastomeric random or block copolymer of a styrene compound such as methylstyrene and a conjugated diene such as 1,3-butadiene or isoprene, and a hydrogenated product of these copolymers. Among these styrene elastomers, a block copolymer of a styrene compound and a conjugated diene is preferable, and these block copolymers are linear and radial. For example, the general formula is represented by the following formula. General formula (AB) _{n + 1} , A- (BA) _n , B- (AB)
_{n + 1,} or _{A'- [(BA) n]} m ( in the above formula, the polymer block A consisting of styrene compound, A'chemical species which is bound to the m (BA) n block, B is a conjugated diene polymer block, and n is 1
~ Integer of 20, m is an integer of 2 or more, A block and A '
The ratio of the above in the whole molecule is 1 to 50% by weight. ) The average molecular weight of these copolymers is 10,000 to 1,000.
50,000, preferably 50,000 to 250,000
Is.

Specific examples of these styrene elastomers include styrene / butadiene random copolymers, styrene / isoprene random copolymers, styrene / butadiene / styrene triblock copolymers, styrene / isoprene / styrene triblock copolymers. , Polystyrene block-terminated styrene-butadiene radial block copolymer, polystyrene block-terminated styrene-isoprene radial block copolymer, styrene-butadiene multiblock copolymer, styrene-isoprene multiblock copolymer, etc. Examples thereof include styrene / conjugated diene block copolymers and products obtained by hydrogenating these. Among these styrene-based elastomers, preferred is hydrogenated styrene.
It is a conjugated diene block copolymer.

Olefin-based elastomer As the olefin-based elastomer, a copolymer of α-olefins such as ethylene, propylene, butene-1, and hexene-1, a copolymer of these with a non-conjugated diene, or hexene-1 A homopolymer of a higher α-olefin such as
Mooney viscosity ML _{1 + 4} measured at 0 ° C is usually 1 to 20
0, preferably 5 to 150, particularly preferably 7 to 100
It is in the range of. Among these olefin elastomers, ethylene elastomers are particularly preferable in terms of quality and stability. Specifically, ethylene / propylene copolymer rubber (EPM), ethylene / butene-1 copolymer rubber, ethylene / propylene / butene-1 copolymer rubber, ethylene / propylene / non-conjugated diene copolymer rubber (EPD).
M), ethylene / butene-1 / non-conjugated diene copolymer rubber, ethylene / propylene / butene-1 / non-conjugated diene copolymer rubber and the like. As specific examples of the non-conjugated diene, dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, dicyclooctadiene, methylenenorbornene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5-methylene-2
-Norbornene, 5-methyl-1,4-hexadiene,
Examples thereof include 7-methyl-1,6-octadiene. Among these elastomer components, an olefin elastomer is particularly preferably used because the surface roughness of the molded body is unlikely to occur.

(E) Component (e): Filler As the filler used as the component (e) of the present invention, either an inorganic filler or an organic filler can be used, and the shape thereof is plate-like, spherical, It may be fibrous or amorphous. Specifically, natural silica such as quartz, synthetic silica produced by a wet method or a dry method, kaolin, mica, talc, natural silicate such as asbestos, calcium silicate, synthetic silicate such as aluminum silicate, magnesium hydroxide, Metal hydroxide such as aluminum hydroxide, metal oxide such as alumina and titania, metal powder such as calcium carbonate, aluminum and bronze, wood powder, carbon black, glass fiber, carbon fiber, aramid fiber, fiber such as alumina fiber Substances, polymeric liquid crystal substances, potassium titanate whiskers, magnesium sulfate whiskers, aluminum borate whiskers, calcium carbonate whiskers, magnesium borate whiskers, zinc oxide whiskers, silicon carbide whiskers, silicon nitride whiskers, sapphire whiskers, beryllia whiskers, etc. Whiskers are listed It is. Among these, mica, talc, calcium carbonate, potassium titanate whiskers, magnesium sulfate whiskers, aluminum borate whiskers, calcium carbonate whiskers and glass fibers are preferable.
Particularly preferred are mica, talc, potassium titanate whiskers and magnesium sulfate whiskers.

These filler components may be surface-treated with a surfactant, a coupling agent or the like. Also,
The filler components may be used alone or in combination of two or more. Various fillers can be appropriately selected and used from the market. In addition, regarding each of the components (a), (b), (c), (d) and (e) constituting the resin composition of the present invention, the combination of the components described above as being preferable is the optimum one. Needless to say.

(F) Component (f): Additional component In the resin composition of the present invention, the above components (a) to (e) are included.
In addition to the essential components described above, the following additional components (optional components) can be included as long as the effects of the present invention are not significantly impaired. Examples of the additional components include additives, specifically, plasticizers such as paraffin oil or fluidity improvers, olefin liquid rubbers, softeners such as conjugated diene liquid rubbers, and colorants. , Antioxidants, neutralizing agents, light stabilizers, ultraviolet absorbers, antistatic agents, lubricants, dispersion aids, molecular weight modifiers, cross-linking agents, nucleating agents, flame retardants Etc. can be mentioned.

(2) Amount ratio The proportion of the above-mentioned components constituting the olefin resin composition of the present invention is as follows. Component (a): low-concentration modified olefin-based resin 10-50% by weight, preferably 30-45% by weight, low-concentration modified olefin-based resin Component (b): high-concentration modified olefin-based resin 2 to 20% by weight, preferably 8 to 15% by weight, component (c): unmodified olefin resin 5 to 40% by weight, preferably 15 to 30% by weight of unmodified olefin resin, component (d): elastomer 20-40 wt% elastomer, preferably 25-3
5% by weight, component (e): filler 15 to 25% by weight, preferably 18 to 23% by weight of filler, and the olefin resin composition of the present invention comprises the above component (a),
It is composed of (b), (c), (d) and (e) and has a composition in the range of 100% by weight in total.

Furthermore, the total content of at least one compound selected from unsaturated carboxylic acids and derivatives thereof in the olefin resin composition when these components are blended in the above-mentioned amount ratio is usually 0.1. ~ 1.5% by weight, especially 0.5 ~
It is preferably in the range of 1.2% by weight.

When the blending ratio of each component in the olefin resin composition is out of the above range, the following problems occur. When the low-concentration modified olefin resin as the component (a) is less than the above range, the adhesive strength of the paint is lowered. On the other hand, if the amount exceeds the above range, the effect proportional to the amount of the modified olefin resin added is not obtained, and the problem of peeling of the surface layer occurs during bumper molding. When the content of the high-concentration modified olefin resin as the component (b) is less than the above range, the adhesive strength of the paint is lowered. On the other hand, even if it exceeds the above range, the effect proportional to the added amount of the modified olefin resin is not obtained, and the low temperature impact resistance required for the bumper is lowered,
It deteriorates the bumper surface after painting. When the amount of the unmodified olefin resin as the component (c) is less than the above range, the fluidity is too good at the time of molding the bumper, burrs are likely to occur, and the surface layer may be peeled off. On the other hand, if it exceeds the above range, the paint adhesion does not reach the level required for the bumper. When the content of the elastomer as the component (d) is less than the above range, the adhesive strength of the coating composition is lowered. On the other hand, if it exceeds the above range, the elastic modulus decreases, and the rigidity required for the bumper becomes insufficient. When the content of the filler of the component (e) is less than the above range, the elastic modulus is lowered and the rigidity required for the bumper is insufficient. On the other hand, when the amount exceeds the above range, there are problems that the moldability of the composition is deteriorated, the large-scale moldability of the bumper is impaired, and the low temperature impact resistance is also lowered.

When the total content of at least one compound selected from unsaturated carboxylic acids or derivatives thereof in the olefin resin composition is less than the above range, the adhesive strength of the coating tends to be low. On the other hand, if the amount exceeds the above range, the physical properties of the composition are deteriorated, and the moldability of the bumper, the peeling of the surface layer, and the like tend to occur to deteriorate the surface appearance and the like required for the bumper.

(3) Composition (Production of Olefin Resin Composition) The olefin resin composition of the present invention is produced by mixing and kneading the above-mentioned respective components. The order of mixing these respective constituents is not particularly limited, and a method of simultaneously mixing the above constituents, any two or several components are mixed and kneaded in advance, and then the remaining components are mixed and mixed.
Any method such as a kneading method may be adopted. mixture·
As a kneading method, a conventionally known kneader such as a Brabender plastograph, a single or twin screw extruder, a strong screw type kneader, a Banbury mixer, a kneader and a roll can also be used.

(4) Olefin Resin Composition (Physical Properties of Material) An olefin resin composition is produced by mixing and kneading the above. Since the olefin resin composition is used as a material for the resin automobile bumper of the present invention,
The blending amounts of the components (a), (b), (c), (d) and (e) are adjusted so that the physical properties of the olefin resin composition show the following physical properties. The flexural modulus at 23 ° C. is 1,400 MPa or more, preferably 1,500 to 1,800 MPa, the Izod impact strength is −30 ° C., 5 kJ / m ² or more, preferably 6 to 9 kJ / m ² , and the MFR value is 5 g / 10 minutes or more, preferably 7 to 16
g / 10 minutes,

If the flexural modulus or the Izod impact strength of the physical properties of the olefin resin composition is less than the above range, the collision performance as a bumper will be insufficient, and thus the resin automobile bumper will not be qualified. Also, MFR
When the value is less than the above range, there is a problem in moldability of the bumper. The flexural modulus is measured according to JIS-K72.
It is the value measured by 03. The measurement of the Izod impact strength is a value measured according to JIS-K7110. Furthermore, the measurement of the MFR is based on JIS-
It is the value measured by K6758.

[II] Bumper molding method In order to manufacture an automobile bumper using the above-mentioned olefin resin composition, any known method such as injection molding, compression molding, vacuum molding, extrusion molding (sheet molding, blow molding), etc. The molding method of can also be applied. In particular, the characteristics of the olefin resin composition used as the material of the present invention can be effectively exhibited even in a bumper formed into a complicated shape by injection molding. The automobile bumper molded from the olefin resin composition of the present invention is directly as it is,
In other words, it is possible to apply coating without performing vapor cleaning with a halogen-based organic solvent that may cause environmental damage, and without performing surface modification treatment such as primer coating or plasma treatment, and good paint adhesion is achieved. It has the characteristic of obtaining sex. However, for the purpose of cleaning and removing hand dust and machine oil adhered to the surface of the molded product inevitably in the steps from the bumper molding of the olefin resin composition to the coating, cleaning with a cleaning liquid that does not contain a halogen-based organic solvent is not recommended. There is no difference. Examples of the cleaning liquid containing no halogen-based organic solvent include solvent-type cleaning liquid, emulsion-type cleaning liquid, and water-based cleaning liquid. Specific examples of the solvent-type cleaning liquid include aliphatic hydrocarbons such as kerosene and d-limonene, aromatic hydrocarbons such as toluene and xylene, and alcohols such as methanol, ethanol and isopropyl alcohol. Examples of the emulsion-type cleaning liquid include those in which a solvent such as kerosene, d-limonene, silicon, or toluene is emulsified and dispersed in water with a surfactant. As the aqueous cleaning solution, an alkaline cleaning solution in which an alkaline component such as sodium hydroxide, potassium hydroxide, sodium silicate, and sodium carbonate is used in combination with a surfactant, an acidic cleaning solution in which an acid component such as phosphoric acid is used in combination with a surfactant, and a nonionic Type neutral cleaning solution using surface-active agent
Examples of the water include pure water and warm water.

[III] Coating When coating an automobile bumper molded from the olefin resin composition of the present invention, a surface modification step such as primer coating or plasma treatment may be omitted from the conventional coating step. it can. That is, the paint can be directly applied directly to the automobile bumper obtained by molding and processing the resin composition. As a coating means, there are spray coating, spray coating, roller coating and the like, but any method can be adopted. As the paint that can be used in the painting step, generally used organic solvent-based paints and water-based paints such as water-soluble resin paints, water-dispersible resin paints and water-based emulsion paints can be used. Specific examples thereof include paints in which these resin components or cross-linking components are acrylic, epoxy, polyester, alkyd, urethane, melamine, and the like.
Among these, preferred paints are acrylic paints, urethane paints and melamine paints, and particularly preferred are melamine paints.

[0035]

EXAMPLES The present invention will be specifically described with reference to Examples and Comparative Examples below. The molding conditions, the coating method and the test method for obtaining the test piece for measuring physical properties and the actual bumper from the compositions produced in the following Examples and Comparative Examples are as shown below. The coating performances in these Examples and Comparative Examples were measured by a cross-cut peeling method of the coating film actually applied to the bumper, and the physical properties were measured by making JIS-specified test pieces.

(1) Molding conditions Bumper molding Molding machine: Japan Steel Works, mold clamping force 4,000 tons Molding temperature: 220 ° C Bumper specifications: Thickness 3.6 mm Width 1,640 mm Depth 630 mm Height 450 mm Test piece molding machine : Toshiba IS170 molding temperature: 220 ° C

(2) Bumper coating method coating: Kansai Paint Co., Ltd., one-component organic solvent-based melamine cross-linking type Rugabake, top coating and clear coating Content: Top coating (30 μm) + clear (10
μm) (wet-on-wet) Paint baking conditions with air spray gun: 140 ° C x 20 minutes

(3) Test Method Paint Adhesiveness Cross-cutting test: Using a single-edged razor, 11 vertical and horizontal parallel lines perpendicular to the surface of the test piece are drawn at 2 mm intervals to make 100 cross-cuts. On top of that, cellophane tape (JIS-Z1
522) was sufficiently pressure-bonded and kept at about 30 ° C. with the coating film surface, and was peeled off at once in a short distance. The state of the part surrounded by the cross-cuts was observed, and the number of cross-cuts not peeled was recorded. Test place: Physical property measurement of bumper top surface MFR: JIS-K6758 conformity, 230 ° C Izod impact strength: JIS-K7110 conformity, (processing notch) -30 ° C measurement bending elastic modulus: JIS-K7203 conformity, width 10 mm, thickness 4 mm The components shown in Table 1 were blended and melt-kneaded at a temperature of 200 ° C. by a twin-screw extruder to obtain pellets.

(4) Raw materials The raw materials used as the compounding ingredients in Table 1 are as follows. (a) Low concentration modified olefin resin [LMPP]: Component (a) LMPP Maleic anhydride content of 0.
Maleic acid graft polypropylene with 7% by weight and MFR of 45 g / 10 minutes. (Production method) Propylene homopolymer 1 having a flexural modulus of 12,000 kg / cm ² and an MFR of 0.8 g / 10 min.
8 g of maleic anhydride and 8 g of benzoyl peroxide were dry blended per kg, and melt-kneaded in a twin-screw extruder set to a preset temperature of 200 ° C. and a rotation speed of 300 rpm. Obtained product (low concentration modified olefin resin [LM
The maleic acid content of PP]) was 0.7% by weight.

(B) High concentration modified olefin resin [HMP
P]: Component (b) HMPP Maleic anhydride-grafted polypropylene having a maleic anhydride content of 7% by weight, produced as described below. (Manufacturing method) In an autoclave having a capacity of 1 liter, the flexural modulus was 12,000 kg / cm ² , and the MFR was 0.
100 g of a propylene homopolymer of 8 g / 10 min is dissolved in 350 g of xylene at 130 ° C. The reaction was carried out while dropping a solution of maleic anhydride 8 g and t-butylcumyl peroxide 6.4 g in xylene 50 g for 2 hours. After the reaction was completed, the mixture was allowed to cool and then acetone 200 g
Was added to the inside of the system to precipitate a product, which was separated by filtration and dried to obtain 106 g of a product. The maleic acid content of the obtained product is 7
% By weight. MFR was too high to measure.

(C) Medium concentration modified olefin resin [MMP
P]: MMPP for Comparative Example Maleic acid-grafted polypropylene having a maleic anhydride content of 2% by weight and an MFR of 600 g / 10 min, produced as described below. (Production method) Propylene homopolymer 1 having a flexural modulus of 12,000 kg / cm ² and an MFR of 0.8 g / 10 min.
24 g of maleic anhydride and 8 g of t-butylperoxybenzoate were dry blended per kg, and the temperature was set to 20.
Melt kneading was performed in a twin-screw extruder set at 0 ° C. and a rotation speed of 300 rpm. The maleic acid content of the obtained product was 2% by weight.

(D) Unmodified olefin resin [BPP]: component (c) ethylene content 4% by weight, flexural modulus 13,500 k
Block polypropylene having a g / cm ² and an MFR of 10 g / 10 minutes.

(E) Elastomer [EPM]: Component (d) Ethylene having a Mooney viscosity L _{1 + 4} (100 ° C.) of 52, a propylene content of 27% by weight and a specific gravity of 0.86.
Propylene copolymer rubber.

(F) Filler: Component (e) Talc The specific surface area is 39,000 cm ² / g and the average particle size is 1.
Talc of 8 to 2.2 μm.

(5) Experimental Examples Examples 1 to 5 and Comparative Examples 1 to 3 Using the above raw materials, the various components shown in Table 1 were blended and melted and kneaded at a temperature of 200 ° C. by a twin-screw extruder. Into pellets. Then, the pellets under the above molding conditions,
A resin-made automobile bumper was prepared by the coating method, and measured and evaluated by the above-mentioned test method. The results are shown in Table 1.

[0046]

[Table 1]

[0047]

The olefin resin is modified with at least one compound selected from unsaturated carboxylic acids or their derivatives, and a low-concentration modified olefin resin and a high-concentration modified olefin resin are used. The resin automobile bumper of the present invention molded from an olefin resin composition in which an olefin resin, an elastomer, and a filler are blended does not require cleaning with a halogen organic solvent, primer coating, or surface modification such as plasma treatment. However, since it can exhibit excellent paint adhesion, it is possible to directly apply paint, has excellent moldability, and has rigidity (flexural elasticity) that can withstand light collisions and low temperature impact resistance ( Since it has an Izod impact), it is extremely useful industrially.

─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Takashi Sugimoto 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Yuka Co., Ltd. Yokkaichi Research Institute (72) Inventor Shoji Yoshino 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Yuka Corporation Yokkaichi Research Institute (72) Inventor Kenji Asai 1 Toho-cho, Yokkaichi-shi, Mie Prefecture Yokkaichi Research Institute (72) Inventor Go Hiramatsu 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Yuka Co., Ltd. Yokkaichi Research Institute (56) Reference JP-A-4-96957 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 23 / 00-23 / 36

Claims (3)

(57) [Claims] 1. The following component (a) as a material component:
Including component (a), including (b), (c), (d) and (e)
10 to 50% by weight, component (b) to 2 to 20% by weight, component (c) to 5 to 40% by weight, component (d) to 20 to 40% by weight, component (e) to 15 to 25% by weight. The composition is such that the total amount of each of the components is 100% by weight, and the physical properties of the material are a bending elastic modulus of 1400 MPa or more at 23 ° C, an Izod impact strength of 5 kJ / m ² or more at -30 ° C, and an MFR value of A resin-made automobile bumper molded from an olefin resin composition of 5 g / 10 minutes or more. Component (a): 0.03 to 1.2% by weight of at least one compound selected from unsaturated carboxylic acids or their derivatives
Low-concentration modified olefin resin component (b) contained: High-concentration modified olefin resin component (c) containing 3 to 12% by weight of at least one compound selected from unsaturated carboxylic acids or derivatives thereof: unmodified olefin resin Resin component (d): Elastomer component (e): Filler 2. The total content of at least one compound selected from unsaturated carboxylic acids or their derivatives is 0.1 to 1.
The resin automobile bumper according to claim 1, which is in a range of 5% by weight. 3. The resin automobile bumper according to claim 1, wherein the surface is directly coated with a melamine paint.