JPS60212452A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE:A composition, obtained by incorporating a specific crystalline ethylene-propylene copolymer with a specific ethylene-propylene copolymer rubber, talc having a specific particle diameter and barium sulfate, and having improved coating performance and high rigidity, molding fluidity and impact resistance. CONSTITUTION:A polypropylene resin composition obtained by incorporating (A) 40-85pts.wt. crystalline ethylene-propylene copolymer having 5-20wt% ethylene content and >=5 melt flow index at 230 deg.C with (B) 10-30pts.wt. ethylene-propylene copolymer rubber having 40-60wt% propylene content and 15-80 Mooney viscosity at 100 deg.C, (C) 2.5-27.5pts.wt. talc having <=6mum average particle diameter and (D) 2.5-27.5pts.wt. barium sulfate having <=1.0mum average particle diameter to give 5-30pts.wt., based on 100pts.wt. total of the components (A), (B), (C) and (D), components (C) and (D).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polypropylene resin composition having excellent paintability, high rigidity, high molding fluidity, and high impact resistance.

Conventionally, polypropylene resin has been widely used in various fields because of its excellent physical properties such as low specific gravity, high rigidity, and chemical resistance, but it has the drawback of poor impact resistance at low temperatures. Therefore, copolymerization with ethylene is carried out,
Impact resistance has been improved by incorporating thermoplastic elastomers such as ethylene-propylene copolymer rubber.

Furthermore, it is widely practiced to add inorganic fillers to polypropylene resins to improve their properties such as rigidity, heat resistance, dimensional stability, and paintability.

Currently, it is common practice to add various thermoplastic elastomers and inorganic fillers to polypropylene resin to obtain polypropylene resin compositions with well-balanced physical properties such as rigidity, paintability, and impact resistance. These materials require contradictory physical properties such as high rigidity, high heat resistance, ease of painting, high molding fluidity, and high impact resistance, and each of these properties is increasingly required to have a high degree of physical property. The various methods currently proposed for these purposes show sufficient physical properties for some of the requirements, but have inferior physical properties for others that are not required by the current market. This is insufficient to meet a high level of physical property balance.

In addition, in order to satisfy various physical properties, it is necessary to increase the amount of rubber components, fillers, etc. added, or use special fillers, etc., which inevitably leads to high prices.

The present invention solves these drawbacks and uses a specific crystalline ethylene-propylene copolymer, an ethylene-propylene copolymer rubber with a specific composition and viscosity, and talc and barium sulfate with specific particle sizes. By blending in a specific amount, an inexpensive polypropylene resin composition having excellent paintability, high rigidity, high molding fluidity, and high impact resistance is provided.

That is, the present invention consists of the following components a) to d), a)
+ b) + c) + d) c) for 100 parts by weight
+d) is 5 to 30 parts by weight of a crystalline polypropylene resin composition.

a) 40 to 85 parts by weight of a crystalline ethylene/propylene copolymer having an ethylene content of 5 to 20% by weight and a melt flow index of 5 or more at 23o0c; b) A propylene content of 40 to 60% by weight at 100°C.
10 to 30 parts by weight of ethylene-propylene copolymer rubber having a Mooney viscosity of 15 to 8 degrees C) Talc having an average particle size of 6 μ4 or less 2.5 to 8 μm
5 to 27.5 parts by weight The resin composition of the present invention has excellent paintability, high rigidity, high molding fluidity, and high impact resistance, and is inexpensive, so it is used for automobile bumpers, fenders, Suitable for use in large molded items such as side molds.

The ethylene/propylene copolymer used in the present invention has an ethylene content of 5 to 20% by weight and a melt flow index of 5 or more at 230°C. If the ethylene content is less than 5 parts by weight, the paintability of the resulting molded product will decrease, and if it remains at 20% by weight, the flexural modulus of the molded product will decrease.

Moreover, if the melt flow index is less than 5, the melt flow index of the obtained polypropylene composition becomes small and the molding fluidity decreases, which is not preferable.

The ethylene-propylene copolymer rubber used in the present invention has a propylene content of 40 to 60 parts by weight and 1
The Mooney viscosity at 00°C is 15 to 80. If the propylene content is less than 40% by weight, the appearance and low-temperature impact resistance of the molded product will deteriorate, and if it exceeds 60% by weight, the flexural modulus and paintability of the resulting molded product will deteriorate, which is not preferred. Furthermore, when an ethylene-propylene copolymer rubber having a Mooney viscosity of less than 15 or more than 80 is added to the crystalline ethylene-propylene copolymer, the particle size of the dispersed ethylene-propylene copolymer rubber may be small or If it becomes too large, the physical properties of the obtained molded product will be unbalanced, which is not preferable.

Further, in the present invention, the amount of the ethylene-propylene copolymer rubber blended is 10 to 30 parts by weight per 100 parts by weight of the polypropylene resin composition, and if it is less than io parts by weight, the impact resistance of the resulting composition will be affected. Paintability decreased, and 30
If the amount exceeds 1 part by weight, molding fluidity and flexural modulus will decrease, which is not preferable.

In the present invention, it is essential to use talc of a specific particle size and barium sulfate in combination.

The talc used in the present invention preferably has an average particle size of 6 μm or less, particularly 5' μm or less.

When talc with an average particle size exceeding 6 μm is used, the impact resistance of the resulting polypropylene resin composition is undesirably reduced.

This talc may or may not be surface-treated. The surface treatment can generally be carried out using a treatment agent such as a silane coupling agent or a fatty acid metal salt organic titanate type. Surface treatment is effective in further improving the effects of the present invention.

Moreover, the barium sulfate used in the present invention has an average particle size of 1.0 μm.
It is barium sulfate with a molecular weight of 11 or less, and is preferably sedimentable due to its surface characteristics. If barium sulfate having an average particle size exceeding 1.0 μm 1 is used, the impact resistance of the resulting polypropylene resin composition decreases, which is not preferable. This barium sulfate can also be used after surface treatment in the same manner as Merck, and in that case, the same effects as above can be obtained.

Regarding the particle size of these inorganic optical fibers, there are commonly used diameters such as directional diameter, directional area equal diameter, equal area diameter, and 5tokes diameter, and various types such as those found in chemical industry handbooks. It is measured using the following measurement method. The average particle size in the present invention is an equal area diameter determined by a light transmission method, and the measurement constant is determined using, for example, a light transmission particle size distribution analyzer model number 5KO2000 manufactured by Seishin Enterprise Co., Ltd., and the 50 coefficient of the particle size cumulative distribution. particle size (generally DlrO
(referred to as ) is used.

The total addition amount of these talc and barium sulfate is in the range of 5 to 30 parts by weight per 100 parts by weight of the polypropylene resin composition, and if the total addition amount of talc and barium sulfate is less than 5 parts by weight, the obtained This is not preferable because the rigidity of the resulting composition does not improve much, and if it is added in excess of 30 parts by weight, the impact resistance and paintability of the resulting composition decreases, especially when the water content of talc and barium sulfate in the resin is reduced. This causes blistering between the resin layer and the paint film, resulting in poor hot water resistance,
Moisture resistance decreases, which is not preferable.

The amount of each of talc and barium sulfate added is 2.5 to 27.5 parts by weight per 100 parts by weight of the polypropylene resin composition.
If the amount of talc added is less than 2.5 parts by weight, the stiffness of the resulting composition will not improve much, and if the amount of barium sulfate added is less than 2.5 parts by weight, the impact resistance will decrease. becomes large, which is not preferable in either case.

The components used in the polypropylene composition of the present invention are mixed using a single-screw extruder commonly used in the art.
This is carried out using a twin-screw pressing machine such as CM or CIM.

Antioxidants that are generally added to polypropylene resin, within a range that does not significantly impair the effects of the present invention,
Heat stabilizers, ultraviolet absorbers, ultraviolet stabilizers, flame retardants, nucleating agents, organic/inorganic pigments, etc. may be used alone or in combination.

The resin composition obtained by such a method can be molded into a predetermined molded article by a commonly used molding method such as an injection molding method, an extrusion molding method, or a compression molding method. Moreover, these molded articles can be used after being painted by the method described in Examples 1 and 2.

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

Melt flow index is AST~I D7-123
8. The flexural modulus was measured according to the method described in AS'vlJ D-790, and the Izod impact value was measured according to the method described in AS'PMD-256.

Example-1 Ethylene content: 7.0 parts by weight, Melt Flow Intex 17.5 crystalline ethylene/propylene propylene copolymer (hereinafter referred to as PP-A): 58 parts by weight, propylene content: 52 parts by weight %, Mooney viscosity at 100°C 37.5 17 parts by weight of theal ethylene propylene copolymer rubber (hereinafter referred to as EPR-A), average particle size 1
．． 15 parts by weight of 3 μm talc and an average particle size of 0.6 μm
To 10 parts by weight of precipitated barium sulfate, further add 2,6-T
-butyl-4-methylphenol 0.05 parts by weight, tetrakis[methylene-3-(35-di-t-butyl-4-
Hydroxyphenyl)propionate comethane o, 13% by weight, 0.1 part by weight of calcium stearate, and P-1-
After adding 0.07 parts by weight of butylbenzoic acid aluminum salt, it was mixed in a henol mixer, and then
Pelletization was performed at °C. The obtained pellets were molded into predetermined test pieces using an injection molding machine, and various physical properties were measured.

Furthermore, paintability was planned using the following method.

The test piece obtained using an injection molding machine was treated with trichloroethane vapor for 30 to 60 seconds, and a two-component acrylic-chlorinated polypropylene base coat was applied to a film thickness of 10 μm, and then A liquid-type acrylic-urethane top coat was applied to a film thickness of 25 μm.
After drying at ℃ for 30 minutes, it was left to stand at room temperature for 24 hours to obtain a paintability test piece. On the coating film of this test piece, cut 100 base lines of 1 vertical line and 1 mm horizontally with a cutter, and adhere cellophane tape. Then, the cellophane tape was suddenly peeled off, and depending on the proportion of the base grains of the remaining paint film,
Initial adhesion was evaluated (base grain peeling test). moreover,
After the paintability test piece was immersed in 40°C warm water for 240 hours, the condition of the coating surface was observed, and then the above-mentioned substrate peeling test was conducted to evaluate hot water resistance.

On the other hand, with the pellet obtained above, the temperature was 30°C and the humidity was 90°C.
After leaving it for one week in the atmosphere of
A flat plate of 160 mm x 80 mm x 2 mrn thick was molded, and the surface condition of the molded product was observed to evaluate the hygroscopicity of the composition.

These evaluation results are shown in Table-1.

Example-2 In Example-1, the amount of PP-A used was 50 parts by weight,
The amount of EPR-A used was 25% by weight, and instead of applying a two-component acrylic-chlorinated polypropylene undercoat paint, low-temperature plasma treatment was applied under the following conditions to evaluate the paintability. The test was conducted in the same manner as in Example-1 except that the test was carried out in the same manner as in Example-1. The results obtained are shown in Table-1.

Plasma processing equipment: Toshiba microwave plasma processing equipment TMZ-2026M Plasma treatment method: Gas: Oxygen, gas pressure: 1.0’rorr.

Crab output 1500W, processing time: 30 seconds Example-3 In Example-1, instead of EPR, -A, the propylene content was 48% by weight, and the Mooney viscosity at 100°C was 60
Ethylene-propylene copolymer rubber (hereinafter referred to as EP
It is expressed as R-B. ) was used, but the test was conducted in the same manner as in Example-1. The results obtained are shown in Table-1.

Examples-4 and 5 In Example-1, the PP-A, EPR-A,
A test was conducted in the same manner as in Example 1 except that the amounts of talc and barium sulfate added were changed to the ratios shown in Table 1.

The results obtained are shown in Table-1.

Example-6 In Example-1, an ethylene-propylene block copolymer (hereinafter referred to as PP-B) having an ethylene content of 12 folds and a melt flow index of 8.8 was used in place of PP-A. The rest was tested in the same manner as in Example-1.

The results obtained are shown in Table-1.

Comparative Example-1 In Example-1, an ethylene-propylene random copolymer (hereinafter referred to as PL) having a double band of ethylene content and a melt flow index of 8.0 was used instead of PP-A.
-C. ) was used, but the test was conducted in the same manner as in Example-1. The results obtained are shown in Table-1.

Comparative Example-2 In Example-1, instead of EPR-A, the propylene content was 27% by weight and the Mooney viscosity at 100°C was 70.
Ethylene-propylene copolymer rubber (hereinafter referred to as EP
It is expressed as R-C. ) was used, but the test was conducted in the same manner as in Example-1. The results obtained are shown in Table-1.

Comparative Examples-3 to 8 In Example-1, the PP-A, EPR-A,
A test was conducted in the same manner as in Example 1 except that the amounts of talc and barium sulfate used were changed to the ratios shown in Table 1. The results obtained are shown in Table-1.

Comparative Example-9 A test was carried out in the same manner as in Example-1 except that talc having an average particle size of 7 μm was used.

The results obtained are shown in Table-1.

Claims (1)

[Claims] Selected from the following a) d) components a) 10 b) + c) + d)
A polypropylene resin composition in which c)-1-d) is 5 to 30 parts by weight per 100 parts by weight. a) Crystalline ethylene-propylene copolymer having an ethylene content of 5 to 30 parts by weight and a melt flow index of 5 or more at 230° C. 40 to 85 parts by weight b) A propylene content of 40 to 600 to 60 parts by weight 0°
10 to 30 parts by weight of ethylene-propylene copolymer rubber having a Mooney viscosity of 15 to 80 at C) Talc having an average particle size of 6 μm or less 2.5 to 27.
5 parts by weight d) Norium sulfate having an average particle size of 1.0 μm or less.
5-27.51 Europe