JPS62153334A - Composite polypropylene composition for automobile bumper - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in heat distortion resistance, impact resistance, etc., by mixing specified two crystalline ethylene/propylene block copolymer with specified two amorphous ethylene/propylene random copolymer and talc. CONSTITUTION:20-40 wt. % crystalline ethylene/propylene block copolyemr (A) of an ethylene content of 4-10 wt. %, a boiling n-heptane-insoluble portion in the polypropylene component >= 95 wt. % and a MFR of 40-65 is mixed with 10-30 wt. % block copolymer (B) which is the same as component A except that it has a MFR of 10-35, 12-20 wt. % amophous ethylene/propylene random copolymer of a Mooney viscosity of 20-25 ML1+4, 4-12 wt. % random copolymer (D) which is the same as component C except that it has a Mooney viscosity of 40-80 ML1+4 and 12-15 wt. % talc (E) having an average particle diameter <= 3mum so that the total of components A and B may be 57-62 wt. % and the total of components C and D may be 20-25 wt. %.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is characterized by heat deformation resistance, impact resistance, appearance, dimensional stability,
This invention relates to a composite polypropylene composition for bumpers that has excellent moldability and paintability.

(Prior art) Recently, Japanese Patent Application Laid-Open No. 57-15984 has been used as a material for automobile bumpers.
As described in Publication No. 1, polypropylene compositions have been attracting attention, and crystalline ethylene-propylene block copolymers (hereinafter referred to as block copolymers) are combined with amorphous ethylene-propylene random copolymers (hereinafter referred to as block copolymers). A composite obtained by blending a random copolymer (referred to as a random copolymer) and talc is known.

(Problems to be Solved by the Invention) However, in order to ensure low-temperature impact properties, these conventionally proposed compositions have a Mooney viscosity of ML. 4 (100
Since 25% by weight or more of a random copolymer with a temperature of 50°C or more is used, moldability and surface gloss are improved.
There are problems. In other words, because the difference in fluidity between the block copolymer and random copolymer that is the base polymer is too large, 70-marks often appear on the surface of the bumper molded product, and the fluidity of the material itself is also insufficient. It wasn't. In addition, if a random copolymer with a Mooney viscosity of 50 or more is used, the gloss of the molded product will be significantly reduced, so bumpers that are not painted or that are only partially painted will have an unfavorable appearance and will have a poor commercial value. There was a problem of lowering the

For this purpose, a random copolymer with a Mooney viscosity of 20 to 50 is used, and a block copolymer (melt flow rate) is used.
(MPR) (g/10 min, 230℃2.16k
Although it has been proposed to use a material with g) of 10 to 30, this also does not have sufficient fluidity. This is because although it has superior fluidity compared to the above-mentioned ones, extremely good fluidity has recently been required.

Therefore, the VFR as a block copolymer is 40'
It has been proposed to improve the fluidity by using a material with a molecular weight of ~65, but this material not only has insufficient flexural modulus or low-temperature impact due to its small molecular weight, but also has a high resistance to random copolymers and block There is a problem in that the above-mentioned 70-mark occurs because the difference in fluidity of the copolymers is too large.

In this regard, the inventors previously proposed a composite polypropylene composition for bumpers with good physical properties by combining two specific types of block copolymers. However, recently, there has been a growing demand for polypropylene components in coatings, and it has become necessary to further improve the coating properties of compositions.

(Means for Solving the Problems) The inventors have developed a material that has high Izotz impact strength at low temperatures, excellent heat deformation resistance, dimensional stability, good moldability and glossy appearance, and is especially easy to paint. Through various trials to develop polypropylene compositions for bumpers with further improved properties, we have developed block copolymers consisting of a combination of two or more specific types, and random copolymers consisting of a combination of two or more specific types. This invention was achieved by blending a specific talc in a specific ratio.

That is, this invention provides: (A) an ethylene content of 4 to 10% by weight, a boiling n-heptane insoluble content of the polypropylene component of 95% by weight or more, and MF
Crystalline ethylene-propylene block copolymer 20-4 of R40-65 (g/10 min, 230°C 2.16 kg)
(B) Ethylene content 4-10% by weight, polypropylene component insoluble in boiling n-heptane 95% by weight or more!
, IFR10-35 (g/min, 230℃2.16kg)
Crystalline ethylene-propylene block copolymer 10~
30% by weight, (C) Mooney viscosity 20-25ML+, 4 (10
0°C) 20-30% by weight amorphous ethylene-propylene random copolymer containing 12-20% by weight of propylene, (
D) Mooney viscosity 40-80ML, (100°C)
4-12% by weight of an amorphous ethylene-propylene random copolymer with a propylene content of 20-30% by weight, (E) 12-15% by weight of talc with an average particle size of 3 μm or less,
The above <A) ~ (θ)j! Including 2 minutes, (Δ), (B)
(The total amount of the 7:7 crystalline ethylene-propylene copolymer is 57 to 62% by weight, and the total amount of the amorphous ethylene-propylene random copolymers of (C) and (D) is 20 to 2% by weight.
5% by weight of a composite polypropylene composition for automobile bumpers.

The polypropylene composition of the present invention has an isot impact strength of 6 kg/cm2 or more at -40°C, a flexural modulus of 12.000 kg/cm2 or more at room temperature,
Gloss rate 60% or more, linear expansion coefficient 70 x 10. -6/
Below, the coating film beading strength regarding the paintability described below is 1.0 kg/cm2 or more, and! , I F R
is 15 g/10 minutes or more (2.16 kg at 230°C), and maintains the impact resistance and paintability of conventional polypropylene bumper materials, while maintaining rigidity, heat deformation resistance, appearance (gloss rate), and dimensional stability. A bumper with significantly improved moldability can be formed with good moldability.

The present invention will be explained below based on the configuration.

The block copolymer used in the polypropylene composition of this invention is the boiling point of the polypropylene component! It is selected from those having an n-heptane insoluble content of 95% by weight or more, more preferably 97% by weight or more. If it is less than 95% by weight, the flexural modulus of the molded article formed from the polypropylene composition of the present invention will be less than 12.000 kg/cm 2 and the heat deformability of the bumper molded article will be insufficient. Further, the block copolymer used in this invention is the following A,
It is constituted by a specific combination of B.

A: Ethylene content 4-10% by weight, MFR40-65
(g/10 minutes, 230℃2.16kg) 20-40% by weight, B: Ethylene content 4-10% by weight, MFRIO~
35 (g/10 minutes, 230℃2.16kg) 15~
30% by weight.

Details regarding component A are as follows.

(a) If the ethylene content is less than 4% by weight, low-temperature impact is insufficient.

(b) If the ethylene content exceeds 10% by weight, the flexural modulus is insufficient. - (C) When MFR is less than 40, the moldability of the molding material is insufficient.

(d) When MFR exceeds 65, flexural modulus and low-temperature impact are insufficient.

(e) If the amount added is less than 20% by weight, moldability is insufficient.

(f) If the amount added exceeds 40% by weight, the flexural modulus and low-temperature impact are insufficient, and flow marks are likely to appear on the surface of the molded product.

Details regarding component B are as follows.

(a) If the ethylene content is less than 4% by weight, low-temperature impact is insufficient.

(5) If the ethylene content exceeds 10% by weight, the flexural modulus is insufficient.

(C) When FA PR is less than 10, fluidity is insufficient.

(d) When MFR exceeds 35, flexural modulus and low temperature impact are insufficient.

(e) If the amount added is less than 10% by weight, the flexural modulus and low-temperature impact are insufficient, and flow marks are likely to appear on the molded product.

(f) If the amount added exceeds 30% by weight, fluidity will be insufficient.

Further, details of the random copolymer of component C used in this invention are as follows.

(a) When the Mooney viscosity exceeds 25, fluidity is insufficient and flow marks are likely to appear on the molded product.

(b) If the Mooney viscosity is less than 20, low-temperature impact, coating film peeling strength, and scratch resistance are insufficient.

(C) When the propylene content is less than 20% by weight, low-temperature impact is insufficient.

(d) If the propylene content exceeds 30% by weight, the flexural modulus and fluidity will be insufficient.

(e) If the amount added is less than 12% by weight, a large amount of component D must be added to maintain low-temperature impact properties, resulting in poor fluidity and the tendency to form flow marks on the surface of the molded product. , the gloss is also insufficient.

(f) If the amount added exceeds 20% by weight, the amount of component D added will be small and the peeling strength of the coating film will be insufficient.

Details regarding component D are as follows.

(a) When the Mooney viscosity exceeds 80, fluidity is insufficient and flow marks are likely to appear on the molded product, resulting in insufficient surface gloss.

(b) If the Mooney viscosity is less than 40, the peeling strength and scratch resistance of the coating film will be insufficient.

(C) If the propylene content is less than 20% by weight, low-temperature impact is insufficient.

(d) If the propylene content exceeds 30% by weight, the flexural modulus and fluidity will be insufficient.

(e) If the amount added is less than 4% by weight, low-temperature impact and coating film peeling strength will be insufficient.

(f) When the amount added exceeds 12% by weight, fluidity and flexural modulus are insufficient. 70-marks tend to appear on the surface of the molded product, and gloss is also poor.

Furthermore, the total amount of C and D added should be 20 to 25% by weight, but the reason for this is that if it is less than 20% by weight, the impact resistance and peeling strength of the coating film will be insufficient, and if it exceeds 25% by weight, This is because liquidity becomes insufficient.

The amounts of C and D to be added are determined by appropriately dividing them within this range of 20 to 25% by weight. Therefore, if C is increased, D is decreased, and vice versa. Within this range, D plays a role in coating film peeling strength, but the amount of D is 12% by weight.
If it exceeds this, the fluidity as a molding material will decrease, and flow marks will likely occur on the surface due to separation during flow.

In addition, in the experiments conducted by the inventors, the contribution to low-temperature impact properties is C,
D was equivalent. That is, C is A because it has a fluidity intermediate between A, B, and D, and has good compatibility with D.

It contributes to increasing impact resistance while preventing separation of B and D during flow.

Further, details of the talc as the E component used in this invention are as follows.

(a) If the average particle size exceeds 3 μm, low-temperature impact is insufficient.

(b) If the amount added is less than 12% by weight, the flexural modulus and linear expansion coefficient will be insufficient.

(C) If the amount added exceeds 15% by weight, low-temperature impact and fluidity will be insufficient.

Therefore, the composition of the present invention, as a random copolymer, has different Mooney viscosities and a combination of two interpolations to prevent a decrease in fluidity and improve low-temperature impact resistance. The combination of copolymers improves fluidity and prevents flow marks while maintaining low-temperature impact resistance and flexural modulus, and the addition of talc improves flexural modulus and improves linear expansion coefficient. This is to make the size smaller.

The total amount of additives A and B is 57 to 62% by weight, which is within such a range based on the amount of other additives C-E. It is not something that is fixed in advance and determines the composition.

Talc may be used untreated, but in order to improve its adhesion and dispersibility with resin, it can be treated with various organic silane coupling agents, fatty acids and their salts, esters, silicone oil, etc. You may use one whose surface has been coated.

In the polypropylene composition of the present invention, pigments, dyes, antioxidants, ultraviolet absorbers, ultraviolet stabilizers, antistatic agents, nucleating agents, lubricants, etc. that are generally used in polypropylene compositions may be used as appropriate. can. As a lubricant, 0.5~
When 1% by weight is used, not only the fluidity but also the flexural modulus is improved. This is considered to be because the oxidized groups improve the dispersion of talc. If the lubricant is less than 0.5% by weight, the effect will be insufficient, and if it exceeds 1% by weight, the low temperature impact will be reduced.

Furthermore, the composition of the present invention has an MFR (g/10 min, 1
Surface gloss can be improved by adding 10 to 20 high density polyethylene in an amount of 3.5% by weight or less. Details of this high density polyethylene are as follows.

(a) MFR (2.16 kg at 190° C.) is less than 10. Thermal fluidity decreases.

(b) When MFR exceeds 20, low temperature impact and surface hardness decrease.

(C) If the amount added exceeds 3.5% by weight, coating film strength, surface hardness, and flexural modulus will decrease.

The polypropylene composition of this invention can be used in Panbali mixer,
Desired physical properties can be obtained by kneading with a batch kneader such as a kneader or a continuous kneader such as a twin-screw extruder. - With an axial kneader, shearing is generally insufficient and good dispersion cannot be obtained, so it is considered difficult to obtain desired physical properties.

Further, the test piece for measuring the physical property values of the present invention can be obtained by directly obtaining a pond by injection molding, a flat plate, etc. by injection molding, and cutting it out from the flat plate.

(Examples) The present invention will be described below based on Examples and Comparative Examples. The various measurement methods used on the opposite side are as follows.

(a) Linear expansion coefficient AST'', measured in accordance with ID 696 (measurement temperature 23°C to 80°C).

(B)! , 1PR Measured in accordance with JIS K 6758.

(c) Flexural modulus (three-point bending modulus) Measured in accordance with JIS K 7'203 (measurement temperature 23°C) (d) Izod impact strength Measured in accordance with JIS K 7110 (measured temperature -
(40℃) (e) Gloss rate Measured in accordance with JIS Z 8741 (reflection angle 60℃)
°) (f) Visually evaluate the flow marks on the external molded product (bumper) (
○...Excellent, Δ...Good, ×...Poor).

(g) Paintability Paintability was evaluated by measuring the peeling strength of the paint film. The peeling strength of the paint film was determined by the following method.

After cleaning the surface of the test piece by contacting the test piece with trichloroethane vapor for 30 seconds, a 1.2-component acrylic-chlorinated polypropylene undercoat paint (Nippon B Chemical Co., Ltd.) was applied.
(manufactured by) to a film thickness of 40 to 50 μm,
After drying at 120 °C for 10 minutes, leave it at room temperature for 10 minutes, and then apply a two-component acrylic-urethane top coat (manufactured by Nippon Bee Chemical) to a film thickness of 30 to 40 μm.
After drying at 120° C. for 20 minutes, the coated product was left at room temperature for 48 hours.

Two parallel incisions are made in the coating film of this φ product with an interval of lam using an NT cutter. Part of the edge of the coating film cut with a width of 1 cm was peeled off in advance, the test piece was fixed on the fixed side of the tensile tester, and a part of it was peeled off on the movable side.・The coating film was fixed. , 10m in the direction of 180°
The peeling strength of the coating film at a width of 1 cm was determined by pulling at a speed of m/min.

Example 1 A block copolymer of the above-mentioned A component (MFR40-65) was used as Te A1 (manufactured by Sumitomo Chemical Q@, AX568,
MFR60) was selected, and Bl (AY-56 manufactured by Sumitomo Chemical ■) was selected as a block copolymer of component B (MFRIO~35).
4. Select C component (Mooney viscosity 20~
25) as a random copolymer of C1 (Japanese Synthetic Rubber ■
Co., Ltd., EPO2, Mooney viscosity 24), and as a random copolymer of component B (Mooney viscosity 40-100),
1 (Japanese Synthetic Rubber Seimi PO7 Mooney viscosity 70),
Select B2 (Mooney viscosity 45) and add talc Tl (
manufactured by Fuji Talc, LMS200, average particle size 1.8 μm),
CB (manufactured by Asahi Su-Maru) was selected as carbon black.

After weighing AI to 33% by weight, B1 to 27% by weight, C1 to 15% by weight, Dl to 9% by weight, TI to 14% by weight, and CB to 1% by weight to give a total weight of 2.7 kg. Mixed using a Henschel mixer. This mixture was put into a Pambari mixer and thoroughly kneaded, and then made into pellets using a single screw extruder. This was designated as Pl. Pi was injection molded to obtain a test piece for evaluating physical properties and a flat plate for painting, and the above-mentioned MFR was measured. In addition, as mentioned above, physical properties,
Paintability was evaluated. The results obtained are shown in Table 1.

Example 2 The composition shown in Example 1 was added with polypropylene wax PI! as a lubricant. I (manufactured by Sanyo Chemical, Viscoal TS-2
00) was added externally in an amount of 0.5% by weight. This was treated in the same manner as in Example 1. This was designated as P2. The properties of P2 were evaluated as described above, and the results are shown in Table 1.

Example 3 In the composition shown in Example 1, a silane coupling agent SC (manufactured by Nippon Nijika, Al10) was used as a surface treatment agent for talc.
0), 0.2% by weight of antioxidant AD (Ilkanox 1010, manufactured by Nippon Ciba-Gaigi), 1% by weight of ultraviolet absorber UA (Chinu Bin 326, manufactured by Nippon Ciba-Gaigi).
0.1% by weight, 0.3% by weight of ultraviolet stabilizer US (Tinuvin 622LD, manufactured by Nippon Ciba-Geigi), 0.3% by weight of antistatic agent AB (manufactured by Lion, Enadicol),
Each was added externally. This was treated in the same manner as in Example 1. This was designated as P3. The characteristics of P3 are shown in Table 1.

Examples 4 to 6 The composition shown in Table 1, except that high-density polyethylene E was used! , +690 (manufactured by Chisso Petrochemical Co., Ltd., MFR13) by the method shown in Example 1 to obtain P4 to P6.

The characteristics of P4 to P6 were evaluated and shown in Table 1.

Example 7.8 The block copolymer of component A was A2 (manufactured by Idemitsu Petrochemicals, J5053HMFR50), and the block copolymer of component B was 82 (J3053HM, manufactured by Idemitsu Petrochemicals).
FR30), T2 as talc (Asada Seifun, MMR
The average particle size was 1 μm) and the composition shown in Table 1 was used in the same manner as in Example 1 to obtain P7. Obtained P8. P7 and P
The characteristics of each sample were evaluated and shown in Table 1.

Example 9 The block copolymer of A is A3 (K7050 MFR50, manufactured by Chisso Petrochemicals), and the block copolymer of B is B3 (K7073 MF, manufactured by Chisso Petrochemicals).
R25), C2 as a random copolymer (manufactured by Japan Synthetic Rubber, IEPOI Mooney viscosity 21), T3 as talc
(MPloo manufactured by Fuji Talc, average particle size 2.8 μm
) and the composition shown in Table 1 in the same manner as in Example 1 to obtain P9.

The characteristics of this P9 were evaluated and shown in Table 1.

Example 10 A4 (manufactured by Mitsubishi Yuka Co., Ltd.) as the block copolymer of A
BCO5CMFR30) and B4 (BCO3CMFR30 manufactured by Mitsubishi Yuka Co., Ltd.) as a block copolymer of B were used and treated in the same manner as in Example 1 with the composition shown in Table 1 to obtain Plo.

The characteristics of this PIO were evaluated and shown in Table 1.

Comparative Examples 1 to 7 The composition shown in Table 1 was treated in the same manner as in Example 1, and the pH
P17 was obtained. However, as the block copolymer 85 manufactured by Nichisei, K7030, MFR9 manufactured by Chisso Petrochemicals was used. Table 1 shows the results of evaluating each characteristic at pH ~ P17.

(Effect of the invention) As explained above, the composition of the present invention has a specific A
A block copolymer of component B is used in combination in a specific ratio, a random copolymer of component C and D is used in combination in a specific ratio, and talc of 3 μm or less as component E is used in a combination of 12 to 15 μm. As is clear from the Examples and Comparative Examples, by calculating the weight percentage, the desired characteristic values were obtained in VFR, flexural modulus, Izot impact strength, gloss rate, appearance, and paintability, and a well-balanced product was obtained. The effect is that the bumper can be formed with good moldability.

Claims (1)

[Claims] 1. (A) Ethylene content: 4 to 10% by weight, polypropylene component insoluble in boiling n-heptane of 95% by weight or more, melt flow rate (MFR): 40 to 65 (g/10 minutes);
230°C (2.16 kg) crystalline ethylene-propylene block copolymer 20-40% by weight, (B) ethylene content 4-10% by weight, boiling n-heptane insoluble content of polypropylene component 95% by weight or more, MFR 10- 35 (g/
(C) Mooney viscosity 20-25 ML_1_+_4 (100°C) amorphous ethylene-propylene content 20-30% by weight Propylene random copolymer 12-20% by weight, (D) Mooney viscosity 40-80ML_1_+_4 (100°C) Propylene content 20-30% by weight amorphous ethylene-propylene random copolymer 4-12% by weight, (E) It contains 12 to 15% by weight of talc with an average particle size of 3 μm or less, the above components (A) to (E), and the total amount of the crystalline ethylene-propylene copolymer of (A) and (B) is 57 to 6% by weight.
2% by weight, and the total amount of the amorphous ethylene-propylene random copolymer of (C) and (D) is 20 to 25% by weight.
A composite polypropylene composition for automobile bumpers, characterized in that: