JPS6375054A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having high and balanced rigidity and impact resistance and excellent coatability and surface scratch resistance and suitable as an exterior trim part of automobile, by compounding a polypropylene resin with specific amounts of talc subjected to a specific surface- treatment, barium sulfate and calcium carbonate having respective specific particle diameters. CONSTITUTION:The objective composition is produced by compounding (A) 40-80wt% crystalline ethylene-propylene block copolymer having an ethylene content of 3-30wt% and a melt flow index (230 deg.C) of >=4g/10min with (B) 30-10wt% ethylene-propylene copolymer rubber and/or ethylene-propylene-diene terpolymer rubber having a propylene content of 10-90wt% and a Mooney viscosity of 15-80 at 100 deg.C, (C) 2-25wt% talc which is surface-treated in a (semi)dry pulverizer (e.g. jet-stream pulverizer), (D) 2-25wt% barium sulfate having an average particle diameter of <=1mum and (E) 1-10wt% calcium carbonate having an average particle diameter of <=5mum (the sum of the components C, D and E is 5-35wt%).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polypropylene resin composition that has a good physical property balance of high rigidity and high impact resistance, excellent paintability, and good surface scratch resistance.

[Conventional technology]

Conventionally, polypropylene resin has been widely used in various fields due to its excellent physical properties such as low specific gravity, high rigidity, and chemical resistance, but #Ii at low temperatures? It had the disadvantage of being inferior in gender. Therefore, copolymerization with ethylene is carried out, and ethylene-propylene copolymer rubber (hereinafter referred to as EPR) is used.
Impact resistance has been improved by blending thermoplastic elastomers such as ethylene-propylene-diene terpolymer rubber (hereinafter referred to as EPDM).

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. Currently, various proposals for these purposes show sufficient physical property values for some of the requirements, but are inferior in other physical properties, and do not have the advanced physical property balance required by the current market. The present inventors have previously developed a specific crystalline ethylene-propylene copolymer, an EPR with a specific composition and viscosity, and a particle size that improves these drawbacks. By blending specified amounts of talc and barium sulfate, we proposed a polypropylene resin composition that has excellent paintability, high rigidity, high molding fluidity, and high impact resistance (Japanese Patent Application Laid-Open No. 1983-1989).
-212452, Japanese Patent Application No. 80-222824)
.

However, when these compositions are applied to parts such as the exterior panels of automobiles, and are left unpainted or partially painted, they have the disadvantage that the unpainted surface has poor surface scratch resistance. was.

[Problems to be solved by the present invention]

An object of the present invention is to provide a polypropylene resin composition that has good surface scratch resistance, excellent paintability, high rigidity, high molding fluidity, and high impact resistance.

[Means to solve the problem]

Therefore, as a result of intensive studies, the present inventors discovered that by using talc surface-treated by a specific method, barium sulfate and calcium carbonate with defined particle sizes, and further adding a defined amount of a nucleating agent. The present invention was based on the discovery that the addition of these compounds significantly improves surface scratch resistance.

That is, the resin composition of the present invention is a) Ethylene content is 3 to 30% by weight, ■ is 48/l.

111n or more crystalline ethylene-propylene block copolymer 40-sob amount%b) EPR and/or 1◆ having a propylene content of 10-90% by weight and a Mooney viscosity of 100° C. (ML) of 15-80 4 is 30-10% by weight of EPDM C) 2-25% by weight of talc surface-treated with a surface treatment agent in a dry or semi-dry pulverizer 2-25% by weight of barium sulfate having a mean particle size of IJLII or less; and e) 1 to 1 calcium carbonate having an average particle size of 5- or less.
0% by weight, and the total amount of the talc, barium sulfate and calcium carbonate is 5 to 35% by weight of the resin composition. This resin composition can further contain 0.5% by weight or less of a nucleating agent.

In the present invention, the pulverizer for producing component b) is preferably a jet stream type pulverizer, and more preferably a fluidized bed type jet pulverizer is used as the jet stream type pulverizer.

Component a) used in the invention has an ethylene content of 3 to 30
It is a crystalline ethylene-propylene block copolymer with weight % and Ml of 4 g/10 min or more. If the ethylene content is less than 3% by weight, the impact resistance and paintability of the resulting composition will decrease, and if it exceeds 30'jflK1%, the rigidity will decrease and such polypropylene resins will have poor productivity. ML is 43/lGm, which is undesirable in any case since the cost of the resulting composition is high.
If it is less than in, the fluidity of the resulting composition will decrease, which is not preferable.

Component b) used in the invention is propylene 100
°C content 10-80% by weight, Mooney viscosity (ML)
EPR, EPDM, and mixtures thereof, in which l◆4 is 15 to 80. When a propylene content of less than 10% by weight is used, the impact resistance of the resulting composition decreases, and 90% by weight
If a material exceeding this value is used, the appearance of the molded product will deteriorate, and
It is difficult to handle and is therefore impractical.

If EPR or EPDM, which has 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 rubber component becomes too small or too large, resulting in problems with the resulting molded product. In addition to worsening the balance of physical properties, if it is less than 15, the paintability of the obtained composition and the appearance of the molded product will deteriorate, and if it exceeds 80, the fluidity of the composition will decrease and the moldability will deteriorate. The case is also unfavorable.

Note that the diene that is the third component of EPDM includes ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, and the like.

Component C) used in the present invention is talc that is surface-treated by being ground with a surface-treating agent in a dry or semi-dry mill, or surface-treated with a surface-treating agent in the mill. Such talc can be used with surface treatment agents such as organic silane-based and titanium-based coupling agents, various surfactants, silicone oils, various silane compounds, metal soaps, higher alcohols, polyolefins, and unsaturated carboxylic acid-modified polyolefins. It can be obtained by premixing it with talc or feeding it separately to a pulverizer, and performing surface treatment at the same time as pulverization. Here, the ratio of the inorganic filler to the surface treatment agent is usually preferably about 0.01 to 5 parts by weight per 100 parts by weight of the inorganic filler, that is, 0.01 parts by weight in order to increase the surface treatment effect. On the other hand, from the viewpoint of improving the balance of physical properties such as rigidity, impact resistance, heat resistance, and surface properties of the resulting resin composition, the amount is preferably 5 parts by weight or less, and if it exceeds 5 parts by weight, the rigidity In any case, this is not preferable because not only the impact resistance and the like may deteriorate, but also the cost increases.

The above-mentioned pulverizer may be one that can perform fine pulverization or fine pulverization in a dry or semi-dry manner, such as a micron mill, a jet stream pulverizer, a ball mill, a micronizer, a turbo mill atomizer, etc. However, from the viewpoint of grinding efficiency, grinding time, and workability, jet air flow grinders such as micronizer type, reductionizer type, impact type, opposed type, and fluidized bed type are preferable. Particularly preferred is a fluidized bed jet mill.

By using such talc, not only the surface scratch resistance of the surface of the obtained molded article is greatly improved, but also the impact resistance is greatly improved.

Component d) of the present invention is barium sulfate with an average particle size of 1.0 μ or less, and from its surface properties, it is preferably sedimentable. It is not preferable to use barium sulfate having an average particle diameter of more than 1.0 mm because the impact resistance of the resulting composition decreases.

Component e) of the invention is calcium carbonate with an average particle size of 5- or less. If calcium carbonate exceeds 1.5, the impact resistance of the resulting composition will decrease, the surface scratch resistance of the product will deteriorate, and the appearance will also deteriorate, which is undesirable. It may be either high quality or light, and these can be surface treated using the same method as the aforementioned talc or other methods.
By performing surface treatment, effects similar to those obtained with talc can be obtained.

The average particle diameter of these inorganic fillers is the isoplane grain diameter determined by the light transmission method, and the value determined as the particle diameter at 50% of the cumulative particle size distribution (generally referred to as D5°). use

The reason why the blending ratios of these components a) to e) are specified as described above is as follows. The amount of component a) is 40
If the amount of component b) is less than 10% by weight, the physical property balance of rigidity and impact resistance of the resulting composition will decrease, and if it exceeds 80% by weight, the impact resistance will decrease, which is undesirable in either case.The amount of component b) is 10% by weight. If the amount of component C) is less than 2% by weight, the impact resistance and paintability of the resulting composition will decrease, and if it exceeds 30% by weight, the rigidity will decrease, so both are undesirable.If the amount of component C) is less than 2% by weight, the resulting composition If the amount exceeds 25% by weight, the impact resistance will decrease and the surface appearance of the product will deteriorate. If the amount of component d) is less than 2% by weight, the impact resistance of the resulting composition will decrease and the surface appearance of the product will deteriorate; if the amount exceeds 25% by weight, there will be no improvement in impact resistance, surface appearance, and rigidity. If the amount of component e) is less than 1% by weight, the resulting product will have poor surface scratch resistance, and if it exceeds 10% by weight, the product will have poor surface scratch resistance. In addition to deteriorating the appearance, impact resistance also decreases, and both cases are unfavorable.

If the total amount of components C), d) and e) is less than 5% by weight, the resulting composition will have low rigidity and poor surface scratch resistance;
If it is added in an amount exceeding 5% by weight, the impact resistance of the composition will decrease, the appearance of the product will deteriorate, and the paintability will decrease.In particular, the water content of talc, barium sulfate and calcium carbonate in the resin will cause the resin layer to deteriorate. This is undesirable because it causes blistering between the paint and the paint film, resulting in a decrease in hot water resistance and humidity.

By adding 0.5 parts by weight or less of a nucleating agent to 100 parts by weight of the resin composition consisting of components a) to e), the rigidity and surface scratch resistance of the composition can be further improved. The amount of these nucleating agents added may be 0.5 parts by weight or less; adding more than this is not preferable because the above-mentioned improvement effect will be small and the cost will be high.

Examples of these nucleating agents are benzoic acid, toluic acid, p
Metal salts of aromatic monocarboxylic acids such as -tert-butylbenzoic acid, 1,3,2,4-di(benzylidene)sorbitol, 1,3,2,4-di(p-ethylbenzylidene)sorbitol Examples include metal salts of aromatic phosphoric acid compounds such as dibenzylidene sorbitol such as dibenzylidene sorbitol, sodium bis(4-tert-butylphenyl) phosphate, sodium methylenebis(2,4-di-tert-butylphenol) phosphate, etc. ．． These nucleating agents can be used alone or in combination of two or more.

In the present invention, anti-breathing agents, lubricants, ultraviolet absorbers,
Various additives such as ultraviolet stabilizers, heat stabilizers, antistatic agents, and organic or inorganic pigments may be added singly or in combination. Examples of these various additives include those commonly added to polyolefin resins, and they may be used within a range that does not significantly impair the effects of the present invention. Further, if necessary, resins other than the polyolefin resin used in the present invention and inorganic fillers other than components c), d), and e) can also be used in combination.

The resin composition of the present invention is usually obtained by premixing each component in a mixer such as a Henschel mixer, and then melt-kneading and pelletizing in a single-screw or twin-screw extruder. It can be molded into a product by a molding method such as extrusion molding, injection molding, rotational molding, or compression molding.

〔Effect of the invention〕

The polypropylene resin composition according to the present invention has a physical property balance of high rigidity and high impact resistance, has excellent paintability and moldability, and has good surface scratch resistance. Suitable for exterior parts such as side moldings, bumpers, etc.

〔Example〕

The present invention will be specifically explained below with reference to Examples and Comparative Examples. In the following description, Ml is ASTM O-1
238, bending modulus is ASTM D-790, bending strength is ASTM D-790, Izod impact strength is ASTM
TM D-256, heat distortion temperature ASTM D-84
Measured according to 8.

Surface scratch resistance was visually determined by the following method.

Sample 80 x 180 x 2 mat grained flat plate (colored with 1 part by weight of red carbon black = 5:1 pigment) Grain shape Elliptical shape with convex area of 3 + sm2 depth approximately 0.
1mm Measurement method Using a pencil scratch test device specified in JIS-K 5401, a 100 yen cupronickel coin was attached instead of a pencil, and the surface of the sample was scratched with a load 1 of 1.50 kg, and the extent of the scratch was measured. I judged it.

Judgment criteria ■: No scratches at all O: //
Δ: Almost not observed Δ: // Slightly observed ×: Approved Paintability was evaluated by measuring peel strength and hot water resistance using test pieces obtained by the following two coating methods. Ta.

An 80 x 240 x 2 am flat plate obtained using an injection molding machine was used as a test piece, and a two-component acrylic-chlorinated polypropylene undercoat was applied to it to a film thickness of 15 mm. After drying at 90°C for 30 minutes, apply a two-component urethane top coat to a film thickness of 100.
It was dried at 80° C. for 40 minutes and further left at room temperature for 48 hours to obtain a paintability test piece (test piece-8).

Test piece B was obtained in the same manner as coating method A, except that instead of applying an undercoat, plasma treatment was performed under the following conditions.

Plasma treatment conditions: Mounting head: Toshiba microwave blast treatment device TMZ-
2028M Processing gas: Oxygen processing time: 30 seconds Gas pressure crab 1. OTorr Gas flow rate: 480cc/win Micro-liquid crab 1500W 肚正ゑ1 Each of the test specimens A and B obtained by the above method was cut with a cutter knife to a width of 1.0cm, and an Instron tensile tester was used to test the specimens. ) The 180°C peel strength of the coating film was measured by pulling at a speed of em/+in.

Test pieces A and B obtained by the above method were immersed in warm water at 40° C. for 240 hours, and then the state of the coating film surface was observed.

O: No blistering of the coating film, etc. Δ: L/ Slightly present ×: // Considerably present The components used in the Examples and Comparative Examples are as follows.

Ryoko Table-1 Dennorpornene, iodine i value 15.0 or "L" D Table-3 Talc-A 100 parts by weight of talc having a normal particle size distribution of 10 μs in terms of average particle diameter, and 1 part by weight of dimethylpolysiloxysilazane.
．． 0 parts by weight were separately supplied to a fluidized bed counterjet mill 400 AFC type crusher manufactured by Albine AG, West Germany, and subjected to crushing surface treatment under the following conditions to obtain surface treated talc (Talc-A). .

Processing conditions Wind 1 11320m”/Hr Grinding pressure
fli kg/c (using compressed air) Classifier rotation speed 4000 rP layer Talc-B Talc-A using N,N-bis(2-hydroxyethyl)laurylamine instead of dimethylpolysiloxane silazane.

Talc-C Only pulverized without using any surface treatment agent.

Talc-D Dimethylpolysiloxysilazane t, oii part and talc-
Mixed with 100 parts by weight of C in a Henschel mixer.

[Precipitated barium sulfate production with a flat average particle size of 0.8 - Examples 1 to 9 The above components a) to e) were distributed in the proportions shown in Table 5,
0.05 part by weight of 2,6-tert-butyl-4-methylphenol, 0.1 part by weight of calcium stearate and tetrakis[methylene-3-(3,5-tert-butyl-4-methylphenol) -Hydroxyphenyl)propione-837220, 1 part by weight was added and mixed in a Henschel mixer, and then pelletized at 210°C using a 40 mmφ-screw extruder.

The obtained pellets were molded into predetermined test specimens at 210° C. using an injection molding machine, and the physical properties of each specimen were measured.

The results are shown in Table-5.

Examples 10 and 11 pt@rt-butylbenzoic acid aluminum salt (nucleating agent-A) and 1,3-2,4-di(p-ethylbenzylidene) sorbitol (nucleating agent-B) as nucleating agents )
The test was conducted in the same manner as in Example 1, except that the ingredients were blended in the proportions shown in Example 5. The results obtained are shown in Table-5.

Example 12 A test was conducted in the same manner as in Example 1, except that 10 parts by weight of EpR-A was replaced with 10 parts by weight of EPDM-A.

The results are shown in Table-5.

Comparative Examples 1 to 11 The types and amounts of components a) to e) were set to the proportions shown in Table 6, and tests were conducted in the same manner as in Example 1, and the obtained results are shown in Table 6.

Claims (1)

[Claims] 1.a) Ethylene content is 3 to 30% by weight, melt flow index (MI) at 230°C is 4g/10m
b) Crystalline ethylene-propylene block copolymer with a polypropylene content of 10 to 90% by weight and a Mooney viscosity at 100°C (ML^1^0^0^°C_1_+_4) of 15 to 80% by weight. 80 ethylene-propylene copolymer rubber and/or ethylene-propylene-diene terpolymer rubber 30 to 10% by weight c) Talc 2 surface-treated with a surface treatment agent in a dry to semi-dry grinder ~25% by weight d) Average particle size 1μ
m) 2 to 25% by weight of barium sulfate, and e) 1 to 1% of calcium carbonate, with an average particle size of 5 μm or less.
0% by weight of the polypropylene resin composition, wherein the total amount of the talc, barium sulfate and calcium carbonate is 5 to 35% by weight of the resin composition. 2. The resin composition according to claim 1, wherein the pulverizer is a jet stream type pulverizer. 3. The resin composition according to claim 2, wherein the jet stream type pulverizer is a fluidized bed type jet pulverizer. 4. The composition according to claim 1, which contains a nucleating agent in an amount of 0.5% by weight or less of the resin composition.