JPS62280267A - Polypropylene resin composition having improved coatability - Google Patents

Abstract

PURPOSE:To obtain a resin compsn. which has excellent coatability and scarcely causes lowering in flexural modulus, by mixing a mixture of PP and an ethylene/alpha-olefin copolymer with an unsaturated dicarboxylic acid and an org. radical generating agent and heat-treating the mixture. CONSTITUTION:A resin compsn. is obtd. by mixing 100pts.wt. mixture composed of 80-60wt% polypropylene (A) and 20-40wt% ethylene/alpha-olefin copolymer (B) with 0.5-2pts.wt. unsaturated dicarboxylic acid and/or anhydride (C) and 0.01-0.2pt.wt. org. radical generating agent (D) in a molar ratio of C/D of 15-85 and heat-treating the mixture. Polypropylene having an MFR (230 deg.C, load: 2,160g) of 0.5-15g/10min is preferred. The ethylene/alpha-olefin copolymer having a Mooney viscosity of 5-90 is preferred.

Description

Detailed Description of the Invention 6. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a polypropylene resin composition with improved paintability useful for interior and exterior parts of automobiles, exterior parts of electrical equipment, etc. This invention relates to a polypropylene resin composition that exhibits excellent paintability when applied with a top coat without using a primer.

[Conventional technology]

Conventionally, polypropylene resin has excellent mechanical properties, chemical resistance, and good moldability, so it has been used in large quantities for a very wide range of applications, but it has the disadvantage of poor adhesion with paints and poor paintability. has.

As a method of improving the paintability of polypropylene resin, a method is known in which polypropylene resin is heat-treated with an unsaturated compound having a carboxy/L4, hydroxyl group, or epoxy group in the presence of an organic radical generator (Japanese Patent Laid-Open No. 58
-154732, JP-A-58-173135, JP-A-5
8-191706, JP-A-6O-99148).

However, these methods of improving paintability have the disadvantage that mechanical properties, such as flexural modulus, which are the advantages of polypropylene resin, are reduced, and are not necessarily practical.

[Problems to be solved by the present invention]

The present invention was made in the background of the above-mentioned conventional technology, and it is an object of the present invention to significantly improve the coating properties without substantially impairing the high flexural modulus of polypropylene resin.

[Means to solve the problem]

In view of the above-mentioned conventional technical problems, the present inventors conducted intensive research to suppress the decrease in the flexural modulus of polypropylene resin as much as possible and to significantly improve the paintability.
~60 parts by weight, (B) 20 to 40 parts by weight of ethylene-α-olefin, A copolymer, (C) 0.5 to 2 parts by weight of unsaturated dicarboxylic acid and/or its anhydride, and (D) organic radical. Within the range of 0.01 to 0.2 parts by weight of the generator and (C
) / (D) in a molar ratio of 15 to 85, and a polypropylene resin composition obtained by heat-treating a mixture of (g), (B), (C), and (D) has the advantages of polypropylene resin. The inventors of the present invention have discovered that the mechanical strength, especially the flexural modulus, shows little decline and exhibits excellent paintability.

The polypropylene (8) used in the present invention is a crystalline polypropylene homopolymer and/or a crystalline block copolymer containing 1 to 25% by weight of ethylene. Preferably, MFR (260°C 2.5%) is used. 16C1 load) 0.5 to 1!M/10 minutes.MFR is 0.
If the MFR is less than 5, the resulting composition may have poor molding processability, which is undesirable. If the MFR exceeds 15, the fluidity of the resulting composition may become too high, making molding difficult.

On the other hand, the α-olefin used as a copolymerization monomer in the ethylene-α-olefin copolymer of the present invention is an α-olefin having 6 to 12 carbon atoms,
Specific examples include propylene, phthene-1,4-methyl-
Examples include pentene-1, hexene-1, octene-1, etc., and propylene is preferred.

These α-olefins can be used alone or in combination of two or more.

Further, the ethylene-α-olefin copolymer includes those copolymerized with non-conjugated dienes, but those without copolymerization with non-conjugated dienes are preferred.

The weight fraction of ethylene, α-olefin, and non-conjugated diene compound used as necessary in the ethylene-α-olefin copolymer used in the present invention is preferably ethylene/α-olefin/non-conjugated diene compound. Conjugated diene compound =
0.2-0.810.2-0810-0.1, more preferably o, 25-0.7510.25-0.7510-0
．． It is 05. If the weight fraction of ethylene is less than 0.2, it is difficult to obtain excellent coating properties, and if it exceeds 0.8, ethylene-α-
Olefin copolymers are easily decomposed by organic radical generators, and good flexural modulus may not be obtained.

Furthermore, the Mooney viscosity (JISK6300ML,...
100℃) is preferably 5-90, more preferably 20-90
It is 70.

If the Mooney viscosity is less than 5, the mechanical strength represented by the flexural modulus of the resulting polypropylene resin composition may be insufficient, while if it exceeds 90, the processability may deteriorate, such as a decrease in water flow during injection molding. may worsen.

(C) Unsaturated dicarboxylic acid and/or used in the present invention
-! or its anhydride, such as α, β-unsaturated dicarboxylic acid and/or its anhydride, such as maleic acid, itaconic acid, citraconic acid, nadic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, nadic anhydride. Among them, maleic anhydride is particularly preferred.

Furthermore, as an organic radical generator used in the present invention (2), 2,5-dimethyl-2,5-di(t-butylperoxy)hequinine-3,2,5-dimethyl-2,5-di(t-
butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)benzene, 2,2'-bis(t-butylperoxy)-p-diisopropylbenzene, dicumyl peroxide, di-t- Butyl peroxide, t-butyl benzoate, 1,1-bis(1°-butylperoxy)-3,3,5-to! J methylcyclohexane, 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, azobisin butyronitrile, etc., preferably 2,5-dimethyl-2
, 5-di(t-butylperoxy)hexane, 1.6-
They are bis(1,-butylperoxyimprobyl)benzene and 2,2'-bis(t-butylperoxy)-p-isopropylbenzene.

The composition of the present invention is made of such polypropylene 80-6
0 parts by weight, preferably 5 to 65 parts by weight, (B
) 20 to 40 parts by weight, preferably 25 to 35 parts by weight of ethylene-α-oleph, in copolymer, (C') 0.5 to 2 parts of unsaturated dicarboxylic acid and/or its acid anhydride, preferably 1 to 1.5 parts by weight of (D) organic radical generator 0.01 to 0.2 parts by weight, preferably 0.05 to 0
, 15 parts by weight at 170°C to 300°C, preferably 180°C to 250°C, for 0.2 to 60 minutes, preferably 0.5 to 2G using a kneader or extruder such as a Banbury or kneader. It can be obtained by heat treatment for 1 minute.

The ratio of each component of the present invention used during the heat treatment is such that when polypropylene exceeds 80 parts by weight (ethylene-
If the α-olefin copolymer is less than 20 parts by weight, the impact resistance will decrease, which is undesirable, and if it is less than 60 parts by weight, the
ethylene.

-If the amount of the α-olefin copolymer exceeds 40 parts by weight, the flexural modulus decreases too much, which is not preferable.

The amount of unsaturated dicarboxylic acid and/or its acid anhydride used per 100 parts by weight of these polymer components is 0.5 parts by weight.
If it is less than 2 parts by weight, the adhesion with the coating film will deteriorate, which is not preferable, and if it exceeds 2 parts by weight, it may not be possible to obtain a smooth painted surface, which is not preferable.

Also used. If the amount of the organic radical generator is less than 11 parts by weight of O, C, the addition of the unsaturated dicarboxylic acid and/or its acid anhydride may be insufficient, and adhesion to the coating film may be poor, which is not preferable. If it exceeds 0.2 parts by weight, the flexural modulus decreases, which is not preferable. and the unsaturated dicarboxylic acid and/or its acid anhydride/organic radical generator (molar ratio) is 15 to 85, more preferably 20 to 70.
A composition with the best balance in paintability and flexural modulus can be obtained within this range.

If (C) / (D) is less than 15, 0.5 to 2 of (C)
Due to the range of parts by weight, the casing of (D) becomes very large, and the polymer component, especially polypropylene, decomposes too much, resulting in a significant decrease in the flexural modulus, and (C)/(D) becomes 85.
If it exceeds ■), in the range of 0.01 to 0.2 parts by weight (
C) remains in multiple layers, resulting in a decrease in paintability.

Furthermore, in terms of conditions for heat treatment, the heat treatment temperature is 1
If the temperature is lower than 70°C, the polypropylene may not completely melt, so mixing may not be sufficient and a uniform composition may not be obtained, which is undesirable. If the temperature exceeds 600°C, thermal deterioration progresses, which is undesirable. The heat treatment time generally needs to be changed depending on the machine used, the heat treatment temperature, and the decomposition temperature of the organic radical generator, but it is generally 0.
If it is less than 3 minutes, mixing and dispersion is often insufficient, which is undesirable; if it exceeds 30 minutes, there is a strong possibility that mechanical cutting of molecules or thermal deterioration will proceed, which is undesirable.

Before and after heat treatment, the polypropylene resin composition obtained in this manner contains conventional auxiliary additive components such as antioxidants, heat stabilizers, ultraviolet absorbers, colorants, etc., as well as carbon dioxide. Fillers such as calci, rum, kaolin, Merck, asbestos, glass fibers, carbon fibers, aromatic polyamide fibers, etc. can also be added.

As a method of coating the composition of the present invention, the surface of the composition is etched with vapor of trichloroethane, trichlene, etc., and various commercially available paints are applied using an apparatus such as an air gun. Particularly suitable coatings for the compositions of the invention are polyurethane-based coatings.

The polypropylene resin composition of the present invention is useful for interior and exterior materials of automobiles, such as bumpers, spoilers, bodies, inner panel covers, motorcycle exterior materials, and electrical appliance exterior materials.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples.

Note that the physical properties in this example were measured by the following method.

1) A sheet of thickness 2 obtained by beer strength injection molding was degreased with ethanol and then treated with trichloroethane vapor. Polyurethane paint (paint R263, curing agent R23
0 (manufactured by Nippon B Chemical ■) to a thickness of 45 ± 10 μm, and after baking the coated material at 90°C for 4 minutes, it was left for over 48 hours. Peeling angle: 90', pulling speed: 5 Qmm/min
Beer strength was measured.

2) Flexural modulus It was carried out according to JIS K-7203.

3) Izod impact strength Tested according to JIS K-7110. (■ With notch) Note that NB in Table 1 means non-break.

Example 1 Polypropylene (Noblen BC-4. manufactured by Mitsubishi Yuka ■,
MFR=6.4, hereinafter abbreviated as PP-1) 70 parts by weight, ethylene propylene rubber (JSREPO2P, manufactured by Japan Synthetic Rubber ■, Mooney viscosity (MLN+4, 100°C)
= 24, propylene content = 26% by weight) 30 parts by weight,
Maleic anhydride (reagent grade, crushed with a milk wasp) 1
Parts by weight, 1,3-bis(t-butylperoxyisopropyl)benzene (Parriki Dox 14. Kayaku Nouri ■
0.1 part by weight (maleic anhydride/Parlyx 14 (mole ratio) = 34) was mixed in advance and the temperature was set at 190°C (C,: 160T: ).

C2: 170°C, 03-C8 and D 190°C-t=knit Melt mixing was performed using a two-screw directional rotating extruder (PCMτ45, Ikegai Ironworks) at a screw rotation speed of 5 Orpm and an average residence time of 1 minute. After drying and injection molding the resulting composition, physical property tests were conducted. The results are shown in Table-1. This example showed excellent beer strength and impact resistance, and relatively good flexural modulus.

Comparative Example 1 In Example 1, the ratio of PP-1/EP 02P was changed to 85/
A composition was obtained in the same manner as in Example 1 except that 15 was changed,
Physical property tests were conducted. The results are shown in Table-1. Impact resistance is extremely poor due to the large amount of polypropylene used.

Comparative Example 2 In Example 1, the ratio of PP-1/EPO2P was 55/4.
A composition was obtained in the same manner as in Example 1 except that the composition was changed to No. 5, and a characteristic test was conducted. The results are shown in Table-1. The flexural modulus of elasticity decreases sharply due to the large amount of ethylene propylene rubber used.

Example 2 In Example 1, 0.05 parts by weight of Parr Dox 14 (maleic anhydride/Parr Dox 14 (molar ratio) = 6
A composition was obtained in the same manner as in Example 1, except that step 9) was changed, and a physical property test was conducted.

The results are shown in Table-1. It exhibits excellent beer strength and impact resistance, and also has good flexural modulus.

Comparative Example 6 In Example 1, 0.3 parts by weight of Parryoku Dox 14 (
Maleic anhydride/Purrydosox 14 (mole ratio) = 11
) A composition was obtained in the same manner as in Example 1, except that the composition was changed, and physical property tests were conducted.

The results are shown in Table-1. If the amount of organic radical generator is too large, the flexural modulus decreases drastically.

Example 3 70 parts by weight of polypropylene (manufactured by Mitsui Noblen BJHH-G Mitsui Toatsu Chemical Co., Ltd., MFF, 10.0, hereinafter abbreviated as PP-2), ethylene propylene rubber (JSRFP)
30 parts by weight of 02P Japanese synthetic rubber, 1 part by weight of maleic anhydride (special grade reagent, crushed with a milk wasp), 2.5 parts by weight
-Dimethyl-2,5-di(t-butylperoxy)hexane (manufactured by Kayahexa AD Chemical Nouri ■) 0.1 part by weight (maleic anhydride/Kayahexa AD (molar ratio) = 30)
were mixed in advance and the temperature was set at 200°C (C+: 160
℃, C2180℃.

C3 to C8 and D: 200° C. set) Using a two-screw directional rotating extruder (PCM-45 manufactured by Ikegai Iron Works), melt mixing was carried out at a screw rotation speed of 5 Q rpm and an average residence time of 1 minute. After drying and injection molding the resulting composition, physical property tests were conducted.

The results are shown in Table-1. This example shows excellent beer strength and impact resistance, and relatively good flexural modulus.

Comparative Example 4 A composition was obtained in the same manner as in Example 3, except that the amount of maleic anhydride was changed to 3 parts by weight (maleic anhydride/Kayahexa AD (molar ratio) = 89), and the physical properties were tested. carried out. The results are shown in Table-1. Too much maleic anhydride leads to poor beer strength and poor coating film smoothness.

Comparative Example 5 In Example 3, using 1100 parts by weight of PP-2, 6 parts by weight of maleic anhydride, and 0.3 parts by weight of Kayahexa AD (maleic anhydride/Kayahexa AD (molar ratio) = 30) used in Example 3. Melt mixing was carried out under the same conditions using the same extruder. The resulting composition with a maleic anhydride content of 1.5% by weight (
30 parts by weight of the expanded GP-○ in Table 1 and 70 parts by weight of the polypropylene used in Example 3 were further melt-mixed under the same conditions using the extruder described above. The physical properties of the composition thus obtained were tested.

The results are shown in Table-1. Even if only ethylene propylene rubber is made into anhydrous maleate, beer strength is extremely low.

Example 4 In Example 6, ethylene propylene rubber was JSREP
07F (manufactured by Japan Synthetic Rubber ■, Mooney viscosity (ML1+)
4.1.00℃)=70. Propylene content = 27% by weight
) A composition was obtained in the same manner as in Example 3, except that the composition was changed, and physical property tests were conducted. The results are shown in Table-2. It exhibits excellent beer strength and impact resistance, and also has good flexural modulus.

Example 5 In Example B, ethylene propylene rubber was processed by JSREP.
ll (manufactured by Japan Synthetic Rubber ■, Mooney viscosity (MLl +
4, 100℃)=40. Propylene content = 49% by weight
) and polypropylene were previously melt-mixed in a ratio of 3=7 and the composition was prepared in the same manner as in Example 3, except that the resulting mixture was used, and a physical property test was conducted. The results are shown in Table-2. It exhibits excellent beer strength and impact resistance, and also has good flexural modulus.

Comparative Example 6 A composition was obtained in the same manner as in Example 3, except that maleic anhydride was changed to 0.2 parts by weight (maleic anhydride/Kayahexa AD (molar ratio) = 6), and physical property tests were carried out. carried out. The results are shown in Table-2. The amount of maleic anhydride is too small and good beer strength cannot be obtained.

Example 6 A composition was obtained in the same manner as in Example 3, except that 10 parts by weight of Merck (manufactured by Merck SW Nippon Talc ■) was added to the polymers and chemicals used in Example 5, and the physical properties were tested. carried out. The results are shown in Table-2. Even when used in combination with fillers such as talc, beer exhibits excellent strength and impact resistance, and the use of fillers improves the flexural modulus.

Comparative Example 7 A composition was obtained in the same manner as in Example 1 except that no chemicals other than polypropylene and ethylene propylene rubber were used in Example 1, and physical property tests were conducted. The results are shown in Table-2. In the unmodified composition the beer strength is almost zero.

Example 7 In Example 1, ethylene propylene rubber was JSREP
OIP (manufactured by Japan Synthetic Rubber ■, Mooney viscosity (ML1+)
4.100℃)=19. Propylene content = 22% by weight)
A composition was obtained in the same manner as in Example 1 except that the composition was changed to , and physical property tests were conducted. The results are shown in Table-2.

Comparative Example 8 Ethylene propylene rubber 100 used in Example 1
Parts by weight, 1 part by weight of maleic anhydride, 2,5-dimethyl-
A composition containing 0.5% by weight of maleic anhydride obtained in the same manner as in Example 1 using 0.2 parts by weight of 2,5-di(t-butylperoxy)hexane (Table 2 shows MAH-modified EP −
(abbreviated as ■) was obtained. 60 parts by weight of the obtained composition and 70 parts by weight of acid-modified polypropylene (MODICP-300F manufactured by Mitsubishi Yuka Corporation, modification amount 0.1% by weight) were further melt-mixed under the same conditions using the extruder described above. The physical properties of the composition thus obtained were tested. The results are shown in Table-2. When separately acid-modified ethylene propylene rubber components and polypropylene components are mixed, the flexural modulus is extremely low.

Comparative Examples 9-10 In Example B, 2-hydroxyethyl acrylate (abbreviated as HEA in Table-1) or glycidyl methacrylate (abbreviated as GMA in Table-1) was used instead of maleic anhydride.
A composition was obtained in the same manner as in Example 3 except that 2 parts by weight of was used, and physical property tests were conducted. The results are shown in Ju-2. 2
-Hydroxyethyl acrylate or glycidyl methacrylate has an extremely low P--D strength.

〔Effect of the invention〕

According to the present invention, the paintability can be significantly improved without impairing the high flexural modulus that polypropylene resin inherently has, and the impact resistance is also good.

The polypropylene resin composition of the present invention is used for automobile interior and exterior materials,
For example, it is useful for bumpers, spoilers, bodies, inner panels, fenders for automobiles, helmets, and exterior materials for electrical appliances, and is particularly useful for painting with urethane paints, especially for painting top coats without primer treatment. This is particularly useful.

Claims (4)

[Claims] (1) (A) 80 to 60% by weight of polypropylene and (
B) 0.5 to 2 parts by weight of (C) an unsaturated dicarboxylic acid and/or its anhydride, and (D) 100 parts by weight of a mixture consisting of 20 to 40% by weight of an ethylene-α-olefin copolymer. The organic radical generator is added in an amount of 0.01 to 0.
Used within the range of 2 parts by weight and (C)/(D) in a molar ratio of 1
Polypropylene resin composition with improved paintability obtained by heat treating a mixture of 5 to 85 (2) MFR of polypropylene of (A) is 0.5 to 15
g/10 minutes (measurement conditions: 230°C, load: 2160g) The polypropylene resin composition according to claim (1) (3) The ethylene-α-olefin copolymer of (B) is an ethylene-propylene copolymer with a propylene content of 20 to 80% by weight and a Mooney viscosity of 5 to 9 (ML_
1_+_4 (100°C) value)
Polypropylene resin composition described in sections 1) and (2) (4) The polypropylene resin composition according to claims (1) to (3), wherein the unsaturated dicarboxylic acid and/or its anhydride (C) is maleic acid and/or maleic anhydride.