JPH0725987B2 - Paintability-improved polypropylene resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polypropylene resin composition having excellent coating properties and weather resistance after plasma treatment.

[Conventional technology]

Polypropylene resins have excellent chemical properties, physical properties, and moldability, and are lightweight and relatively inexpensive, so they are widely used for various industrial parts including automobile parts.
Especially, in recent years, its use in automobile bumpers has been remarkable.

Conventionally, bumpers for automobiles have generally been unpainted or fully coated, but partially unpainted parts that are partially unpainted are becoming more popular due to design requirements. For this reason, polypropylene resins have been required to have good weatherability as well as good coating properties.

As a method of coating the polypropylene resin bumper,
Previously, the following methods were common. That is, a method of cleaning the bumper surface with a halogen-based organic solvent, followed by primer coating and then topcoating has been carried out.

Nowadays, in order to reduce costs and improve productivity, after cleaning the bumper surface with a halogen-based organic solvent, plasma treatment is performed instead of primer coating, and a method of top-coating is widely used. It's coming.

However, if the bumper washed with the organic solvent is immediately put into the plasma treatment tank, the organic solvent vapor volatilized from the bumper surface hinders the generation of plasma, so that the effective plasma treatment cannot be performed. Therefore, the organic solvent on the bumper surface was removed under a high temperature atmosphere before the plasma treatment.

[Problems to be Solved by the Present Invention]

In order to improve weather resistance and light stability, various kinds of antioxidants, light stabilizers and the like have been conventionally blended in polypropylene resins. After molding this polypropylene resin into a bumper, washing with a solvent and drying in a high temperature atmosphere, these antioxidants, light stabilizers and the like sometimes bleed out on the surface.

For this reason, there has been a problem that the coatability is not improved even if the bumper is plasma-treated.

An object of the present invention is to solve such problems and to provide a polypropylene resin composition which is excellent in weather resistance and in coatability after plasma treatment.

[Technical means for solving problems]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a crystalline ethylene-propylene block copolymer ... 45-88% by weight Thermoplastic elastomer whose main chain is substantially saturated ... 10-35% by weight Inorganic filler ... -In 100 parts by weight of the composition consisting of 2 to 25% by weight, (a) nitrogen-free hindered phenol-based oxidation: 0.03-0.6 parts by weight (b) nitrogen-containing hindered phenol-based antioxidant- .. 0.03 to 0.6 part by weight (c) Benzotriazole type ultraviolet absorber ... 0.03 to 0.5 part by weight (d) Hindered amine type light stabilizer having a molecular weight of 500 or more or less than 500 having no NH bond.・ 0.05
To 1.0 part by weight of the polypropylene resin composition.

The polypropylene resin composition of the present invention uses a nitrogen-containing hindered phenolic antioxidant as an antioxidant in combination with a nitrogen-free hindered phenolic antioxidant, and a light stabilizer having a molecular weight of By using a hindered amine having a molecular weight of 500 or more or having a N-H bond and a molecular weight of less than 500, both weather resistance and coatability after plasma treatment are achieved.

The proportion of each component in the polypropylene resin composition of the present invention is as follows.

Crystalline ethylene-propylene block copolymer, thermoplastic elastomer, and the total amount of inorganic filler 100 wt%, crystalline ethylene-propylene content is 45 ~ 88 wt%, thermoplastic elastomer content 10 ~ 35. The weight% and the content of the inorganic filler are 2 to 25% by weight.

When the content of the crystalline ethylene-propylene block copolymer is less than 45% by weight, the flowability of the polypropylene resin composition is deteriorated and molding becomes difficult. On the other hand, if it exceeds 88% by weight, a molded product having a good balance of rigidity and impact resistance cannot be obtained.

If the content of the thermoplastic elastomer is less than 10% by weight, the impact resistance of the molded product will be poor. On the other hand, if the content of the thermoplastic elastomer exceeds 35% by weight, a molded product having sufficient rigidity cannot be obtained.

When the content of the inorganic filler is less than 2% by weight, there is a problem that the rigidity of the molded product is reduced, and when it exceeds 25% by weight,
The impact resistance of the molded product decreases.

The contents of nitrogen-free hindered phenol antioxidants, nitrogen-containing hindered phenol antioxidants, benzotriazole ultraviolet absorbers, and hindered amine light stabilizers are as shown below.

That is, (a) a nitrogen-free hindered phenolic antioxidant: 0.03 to 0.6 part by weight, based on 100% by weight of the total amount of the ethylene-propylene block copolymer, the thermoplastic elastomer, and the inorganic filler. b) Nitrogen-containing hindered phenol-based antioxidant: 0.03 to 0.6 part by weight (c) Benzotriazole-based UV absorber: 0.03 to 0.5 part by weight (d) Hindered amine-based light stabilizer: 0.05 to 1.0 Make sure to use parts by weight.

If the content of nitrogen-free hindered phenolic antioxidants, nitrogen-containing hindered phenolic antioxidants, benzotriazole ultraviolet absorbers, or hindered amine light stabilizers is less than the above range, weather resistance Run out. On the other hand, if the content is more than the above, these antioxidants and the like may bleed out and the coating property may be deteriorated.

Next, each component of the composition of the present invention will be described.

The crystalline ethylene-propylene block copolymer has an ethylene content of 5 to 25% by weight and an MFR (melt flow rate) of 10 to 70 g / 10 minutes.

When the ethylene content is less than 5% by weight, the impact resistance of the molded product obtained by molding the polypropylene resin composition of the present invention is lowered, which is not preferable. On the other hand, when the ethylene content exceeds 25% by weight, the rigidity of the molded product decreases.

When the MFR is less than 10 g / 10 minutes, the moldability is deteriorated and the appearance of the molded product is likely to be defective. On the other hand, when it exceeds 70 g / 10 minutes, the dispersibility of the thermoplastic elastomer and the like deteriorates and the impact resistance decreases.

From the viewpoint of weather resistance, it is necessary that the main chain of the thermoplastic elastomer is substantially saturated. Specifically, ethylene-propylene copolymer rubber, ethylene-propylene-
Examples thereof include hydrogenated products such as diene terpolymer rubber, ethylene-butene copolymer rubber, styrene-butadiene or styrene-isoprene block or random copolymer rubber.

The inorganic filler is, for example, talc, calcium carbonate, calcium oxide, calcium hydroxide, magnesium carbonate, magnesium hydroxide, magnesium oxide, aluminum hydroxide, magnesium sulfate, barium sulfate, glass powder,
Examples include clay, dolomite, mica, silica, alumina, potassium titanate, wollastonite, fibrous magnesium oxysulfate, and glass fiber. These inorganic fillers may be used alone or in combination of two or more kinds. Particularly preferable inorganic fillers are talc, calcium carbonate, barium sulfate and fibrous magnesium oxysulfate.

The average particle diameter (spherical or tabular) or average fiber diameter (needle-like or fibrous) of the inorganic filler is 5 μm or less, preferably 4 μm or less. And the particle diameter and fiber diameter are 8μ
The content of m or more is preferably 1% by weight or less. If the average particle diameter or the average fiber diameter exceeds 5 μm, the impact resistance of the molded product decreases, which is not preferable.

Examples of nitrogen-free hindered phenol antioxidants include 2,6-di-t-butyl-4-methylphenol and octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl). ) Propionate, pentaerythrityl-tetrakis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate], 3,9-bis [1,1-dimethyl-2- {β- (3-t
-Butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl] -2,4,8,10-tetraoxaspiro (5,5) undecane, triethylene glycol-bis [3- (3-t-butyl) -5-Methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate.

Examples of the nitrogen-containing hindered phenolic antioxidant include (a) 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -S-triazine-2,4,6. − (1H, 3
H, 5H) trione, (b) 2,4-bis- (n-octylthio) -6- (4-
Hydroxy-3,5-di-t-butylanilino) -1,3,5-
Triazine, nitrogen-containing hindered phenolic antioxidants such as triazine, amide-based antioxidants such as N, N'-hexamethylene-bis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) And nitrogen hindered phenolic antioxidants, N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, and the like.

Of these, the triazine type is most preferable.

Examples of the benzotriazole-based ultraviolet absorber include 2- (3-t-butyl-5-methyl-2-hydroxyphenyl-5-chlorobenzotriazole 2,2-methylene-bis [4- (1,1,3,3 -Tetramethylbutyl) -6- (2H-benzotriazol-2-yl)
Phenol, 2- (3,5-di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2 [2-hydroxy-3,5-bis- (α, α) -Dimethylbenzyl) phenyl] -2H-benzotriazole, and the like.

The hindered amine light stabilizer needs to have a molecular weight of 500 or more, or a molecular weight of less than 500 that does not have an NH bond in the molecule. Examples of such hindered amine light stabilizers include the following.

As the one having a molecular weight of 500 or more, dimethyl succinate-1- (2-hydroxyethyl) -4
-Hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, 1,2,3,4-butanetetracarboxylic acid-2,2,6,6-tetramethyl-4-piperidinol tridecyl alcohol Condensate 1,2,3,4-butanetetracarboxylic acid-1,2,2,6,6-tetramethyl-4-piperidinol tridecyl alcohol condensate Poly [[{6- (1,1,3 , 3, -Tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl} {(2,2,6,6
-Tetramethyl-4-piperidyl) imino}] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl)
Imino}], 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n butylmalonate bis (1,2,2,6,6, pentamethyl-4-piperidyl), tetrakis ( 2,2,6,6-Tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, Tetrakis (1,2,2,6,6-tetramethyl-4-piperidyl) 1,2 , 3,4-Butane tetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl)
Sebacate, 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4-
[3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, and the like.

Further, as a compound having a N-H bond in the molecule and a molecular weight of less than 500, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4, 5) Undecane-2,4-
Examples include dione and the like.

As long as the effect of the present invention is not significantly impaired, an antioxidant, a heat stabilizer, which is usually added to polypropylene resins,
An ultraviolet absorber, a flame retardant, a nucleating agent, an organic / inorganic pigment, etc. may be added.

The composition of the present invention can be produced according to a conventional method. Powder or pellets of crystalline ethylene-propylene block copolymer, thermoplastic elastomer or inorganic filler, and nitrogen-free hindered phenolic antioxidant, nitrogen-containing hindered phenolic antioxidant, benzotriazole ultraviolet light An absorber, a hindered amine light stabilizer, etc. are blended and blended with a Henschel mixer or the like. This can be melt-kneaded with a single-screw extruder or a twin-screw extruder to obtain the composition of the present invention. Further, instead of the uniaxial extruder, a roll or a Banbury mixer may be used for melt kneading.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to examples.

Abbreviations of nitrogen-containing hindered phenolic antioxidants and the like used in this example are as follows.

(1) Nitrogen-free hindered phenolic antioxidant AO-1 ・ ・ ・ ・ 2,6-di-t-butyl-4-methylphenol AO-2 ・ ・ ・ ・ octadecyl-3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate AO-3 ... Pentaerythrityl-tetrakis [3-
(3,5-Di-t-butyl-4-hydroxyphenyl) propionate] (2) Nitrogen-containing hindered phenolic antioxidant NAO-1 ・ ・ ・ 1,3,5-tris (3,5-di- t-butyl-
4-hydroxybenzyl) -S-triazine-2,4,6-
(1H, 3H, 5H) Trione NAO-2 ... 2,4-bis (n-octylthio) -6-
(4-Hydroxy-3,5-di-t-butylanilino)-
1,3,5-Triazine (3) Benzotriazole type UV absorber UV-1 ・ ・ ・ ・ 2- (3-t-butyl-5-methyl-2)
-Hydroxyphenyl) -5-chlorobenzotriazole UV-2 ...- 2,2-methylene-bis [4- (1,1,3,3-
Tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] (4) Hindered amine light stabilizer HALS-1 with a molecular weight of 500 or more or a molecular weight of less than 500 that does not have an N—H bond. HALS-1 ... Amber Acid dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate HALS-2 ・ ・ ・ bis (1,2,2,6,6-pentamethyl- 4-
Piperidyl) sebacate HALS-3 ・ ・ ・ 1,2,3,4-butanetetracarboxylic acid-1,
2,2,6,6-Tetramethyl-4-piperidinol tridecyl alcohol condensate HALS-4 ... 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3, 8-Triazaspiro [4,5] undecane-2,4-dione (5) Other hindered amine light stabilizers HALS-5 ・ ・ ・ bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate HALS -6 ... 4-Benzoyloxy-2,2,6,6-tetramethylpiperidine Example 1 (1) Crystalline ethylene-propylene block copolymer (PP-1) (a) Ethylene content 7.5% by weight ( b) MFR 20g / 10 minutes ···· 65 wt% (2) Ethylene-propylene copolymer rubber (EPR-1) (a) Ethylene content 75 wt% (b) Mooney viscosity (ML _{1 + 4} 100 ° C) 20・ ・ ・ ・ 25% by weight (3) Talc (average particle size 2.5 μm) ・ ・ ・ ・ 10% by weight (4) Above (1), (2), and (3 N-containing hindered phenolic antioxidant AO-2 ··· 0.2 parts by weight Nitrogen-containing hindered phenolic antioxidant NAO-1 ··· 0.2 parts by weight per 100 parts by weight Triazole UV absorber UV-1 ・ ・ ・ ・ 0.2 parts by weight Hindered amine light stabilizer HALS-1 ・ ・ ・ ・ 0.3 parts by weight Carbon black (pigment) ・ ・ 0.1 parts by weight Magnesium stearate ・ ・ 0.2 parts by weight Then, after mixing with a Henschel mixer, it was melt-kneaded and pelletized with a twin-screw extruder set at 230 ° C. to obtain a polypropylene resin composition.

This polypropylene resin composition was injection-molded to obtain a test piece for measuring physical properties and a flat test piece of 50 mm × 90 mm × 2 mm.

The flat test piece was exposed to a saturated vapor of 1,1,1-trichloroethane for 30 seconds to clean the surface. It was then placed in an oven set at 90 ° C for 10 minutes to dry.

Next, plasma treatment was performed. The conditions of plasma treatment were as follows.

・ Vacuum 1.0 Torr ・ Microwave output 0.05kw ・ Treatment time 0.3 sec ・ Gas flow rate 600cc / min ・ Treatment gas Air After plasma treatment, 2-component urethane topcoat paint was applied to a film thickness of 40 μm . This is 3 at 120 ℃
It was dried for 0 minutes and then left at room temperature for 48 hours to obtain a coated article.

The paintability of this coated product was evaluated as follows.
It was First of all, apply a cutter knife to the coating of this test piece.
I made a notch in a grid and divided it into 100 sections. This
Each section is 1 mm square. Serote from above
The Paste this cellophane Paint when peeled off
The stripped parcels were counted.

Regarding paintability, ○ when there is no section where the paint is peeled off, △, 1 when 1 to 10 of 100 sections are peeled off
The case of peeling more than one frame was evaluated as x.

Furthermore, the weather resistance was evaluated using the test piece that had been only plasma-treated. The weather resistance was evaluated using a sunshine weatherometer and the black panel temperature was 83 ° C.
Under the conditions described above, the time required for cracks to be confirmed at 50 times magnification was measured.

For the measurement of physical properties, a flexural modulus and Izod impact strength were measured using a test piece for measuring physical properties. Flexural modulus is ASTM D-7
90. Izod impact strength was measured according to ASTM D-258.

Table 1 shows the results of coating properties and physical property measurements.

Example 2 HALS-2 in place of HALS-1 in the hindered amine light stabilizer
A composition was prepared and molded into a test piece in the same manner as in Example 1 except that was used, and the paintability and weather resistance were evaluated. The results are shown in Table 1. However, the flexural modulus and Izod impact strength were not measured.

Example 3 HALS-3 in place of HALS-1 in the hindered amine light stabilizer
A composition was prepared and molded into a test piece in the same manner as in Example 1 except that was used, and the paintability and weather resistance were evaluated. The results are shown in Table 1. However, the flexural modulus and Izod impact strength were not measured.

Example 4 Instead of UV-1 in the benzotriazole type ultraviolet absorber
A composition was prepared and molded into a test piece in the same manner as in Example 1 except that 0.1 part by weight of UV-2 was used, and the paintability and weather resistance were evaluated. However, the flexural modulus and Izod impact strength were not measured.

Example 5 NAO-2 was used in place of NAO-1 as the nitrogen-containing hindered phenol antioxidant, and H was used as the hindered amine light stabilizer.
A composition was prepared in the same manner as in Example 1 except that HALS-2 was used in place of ALS-1, molded into a test piece, and the paintability and weather resistance were evaluated. However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Example 6 AO as a hindered phenolic antioxidant containing no nitrogen
Instead of using 0.2 parts by weight of -2, 0.05 parts by weight of AO-1 and AO-
2 and 0.1 parts by weight of AO-3 were used, and the composition was prepared in the same manner as in Example 1 except that the proportion of the hindered amine light stabilizer HALS-1 was increased to 0.6 parts by weight, and the composition was molded into a test piece. And the weather resistance was evaluated. However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Example 7 A composition was prepared in the same manner as in Example 3 except that the proportion of the nitrogen-containing hindered phenolic antioxidant NAO-1 was reduced to 0.1 part by weight, and the composition was molded into a test piece to improve paintability and weather resistance. evaluated. However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Example 8 A composition was prepared in the same manner as in Example 2 except that the proportion of the hindered amine light stabilizer HALS-2 was increased to 0.6 parts by weight, and the composition was molded into a test piece and evaluated for paintability and weather resistance. However, the flexural modulus and Izod impact strength were not measured.
The results are shown in Table 1.

Example 9 A composition was prepared in the same manner as in Example 1 except that the proportion of UV-1 was reduced to 0.1 parts by weight and the proportion of HALS-1 was increased to 0.4 parts by weight.
It was molded into a test piece and the paintability and weather resistance were evaluated.
However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Example 10 A crystalline ethylene-propylene block copolymer, PP-1
PP-2 with ethylene content 7.5% by weight, MFR 30g / 10min
Was used. HALS-3 was used in place of HALS-1 as the hindered amine light stabilizer. A composition was prepared in the same manner as in Example 4 except for the above, molded into a test piece, and the flexural modulus, Iz
The od impact strength was measured and the paintability and weather resistance were evaluated. The results are shown in Table 1.

Example 11 A crystalline ethylene-propylene block copolymer, PP-2
PP-1 in place of styrene-butadiene block copolymer rubber as a thermoplastic elastomer (SEB
S) was used to prepare a composition in the same manner as in Example 10,
It was molded into a test piece, the flexural modulus and Izod impact strength were measured, and the paintability and weather resistance were evaluated. The results are shown in Table 1.

Example 12 The proportion of the crystalline ethylene-propylene block copolymer was
62% by weight, the proportion of ethylene-propylene copolymer rubber
The inorganic filler was talc and fibrous magnesium oxysulfate (MOS) at 5% by weight, respectively. The types and proportions of the hindered phenolic antioxidants and the like were the same as in Examples 10 and 11.

The bending elastic modulus and Izod impact strength were measured, and the results of evaluation of paintability and weather resistance are shown in Table 1.

Example 13 The proportion of thermoplastic elastomer was reduced to 22% by weight and the proportion of talc was reduced to 5% by weight. Then, the proportion of the crystalline ethylene-propylene block copolymer was increased to 73% by weight. Table 1 shows the results of molding this composition into test pieces, measuring flexural modulus and Izod impact strength, and evaluating coatability and weather resistance.

Example 14 Instead of HALS-1, HALS was used as a hindered amine light stabilizer.
A composition was prepared and molded into a test piece in the same manner as in Example 1 except that No. -4 was used, and the paintability and weather resistance were evaluated. The results are shown in Table 1. However, the flexural modulus and Izod impact strength were not measured.

Comparative Example 1 The composition was prepared and molded into a test piece in the same manner as in Example 1 except that the proportion of the hindered amine light stabilizer HALS-1 was increased to 1.1 parts by weight, and the paintability and weather resistance were evaluated.
However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Comparative Example 2 A composition was prepared, molded into a test piece, and the paintability and weather resistance were evaluated in the same manner as in Example 3 except that the proportion of the benzotriazole-based ultraviolet absorber UV-1 was increased to 0.7 parts by weight.
However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Comparative Example 3 The composition was prepared and molded into a test piece in the same manner as in Example 3 except that the ratio of the nitrogen-containing hindered phenolic antioxidant NAO-1 was increased to 1.2 parts by weight, and the paintability and weather resistance were obtained. The sex was evaluated. However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Comparative Example 4 The composition was prepared and molded into a test piece in the same manner as in Example 9 except that the benzotriazole-based ultraviolet absorber was not added, and the paintability and weather resistance were evaluated. However,
The flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Comparative Example 5 Except that the nitrogen-containing hindered phenolic antioxidant was not added and the amount of the UV absorber UV-1 was increased to 0.2 parts by weight.
In the same manner as in Example 9, the composition was prepared and molded into a test piece, and the paintability and weather resistance were evaluated. However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.
Shown in.

Comparative Example 6 A composition was prepared and a test piece was prepared in the same manner as in Example 1 except that a nitrogen-free hindered phenolic antioxidant was not added, and paintability and weather resistance were evaluated. However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.

Comparative Example 7 Except that no hindered amine light stabilizer was added,
In the same manner as in Example 4, the composition was prepared and molded into a test piece, and the paintability and weather resistance were evaluated. However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.
Shown in.

Comparative Example 8 Except that HALS-5 was used in place of HALS-1 as the light stabilizer,
In the same manner as in Example 4, the composition was prepared and molded into a test piece, and the paintability and weather resistance were evaluated. However, the flexural modulus and Izod impact strength were not measured. The results are shown in Table 1.
Shown in.

Comparative Example 9 In the same manner as in Example 4 except that 0.2 part by weight of HALS-6 was used instead of HALS-1 as the light stabilizer, the composition was prepared and molded into a test piece, and the coating property and The weather resistance was evaluated. However, the flexural modulus and Izod impact strength were not measured.
The results are shown in Table 1.

Comparative Example 10 The ratio of the crystalline ethylene-propylene block copolymer was
It was increased to 87% by weight and the proportion of thermoplastic elastomer was reduced to 5% by weight. The paintability and weather resistance of this composition were evaluated, and the flexural modulus and Izod impact strength were measured. The results are shown in Table 1.

Comparative Example 11 A composition containing no inorganic filler was prepared, and the paintability and weather resistance were evaluated, and the flexural modulus and Izod impact strength were measured. The results are shown in Table 1.

From these examples and comparative examples, the following was found.

Hindered phenolic antioxidants that do not contain nitrogen,
A composition lacking any of a nitrogen-containing hindered phenolic antioxidant, a benzotriazole ultraviolet absorber, and a hindered amine light stabilizer has poor weather resistance.

When the hindered amine light stabilizer does not satisfy the conditions specified in the present application, the composition is inferior in coatability and the adhesion of the coat is poor even after the plasma treatment.

Hindered phenolic antioxidants that do not contain nitrogen,
Even in the case of a composition containing all of a nitrogen-containing hindered phenolic antioxidant, a benzotriazole ultraviolet absorber, and a hindered amine light stabilizer, if these ratios are within the range specified in the present application, weather resistance and Difficulty in paintability.

[Operation and effect of the present invention]

The polypropylene resin composition of the present invention uses a nitrogen-containing hindered phenolic antioxidant together with a nitrogen-containing hindered phenolic antioxidant as an antioxidant. The light stabilizer has a molecular weight of 50 or more, a hindered amine having a molecular weight of 500 or more, or a molecular weight of 50 having no NH bond.
It uses less than 0 hindered amines. Therefore, in the composition of the present invention, the hindered amine light stabilizer or the like hardly bleeds out on the surface. Therefore, the subsequent plasma treatment is effectively performed, and the paintability can be significantly improved.

Therefore, the composition of the present invention can sufficiently satisfy the requirements for compatibility between weather resistance and paintability, which have been recently required for bumper materials.

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Claims (1)

[Claims] 1. A crystalline ethylene-propylene block copolymer: 45 to 88% by weight A thermoplastic elastomer whose main chain is substantially saturated 10 to 35% by weight Inorganic filler: -In addition to 100 parts by weight of the composition consisting of 2 to 25% by weight, (a) a nitrogen-free hindered phenolic antioxidant ... 0.03 to 0.6 part by weight (b) a nitrogen-containing hindered phenolic antioxidant Agent: 0.03 to 0.6 part by weight (c) Benzotriazole type ultraviolet absorber: 0.03 to 0.5 part by weight (d) Hindered amine light stabilizer having a molecular weight of 500 or more or a molecular weight of less than 500 having no NH bond. ... 0.05
A polypropylene resin composition containing about 1.0 part by weight.