JPH01271451A - Resin composition for automobile exterior furnishing - Google Patents

Abstract

PURPOSE:To obtain a resin composition improved in high-temperature rigidity and paintability by mixing a heat-resistant high-rigidity propylene/ethylene block copolymer in which the streoregularity of the propylene homopolymer part is high with two amorphous EP copolymers and calcium carbonate particles and talc particles of specified particle diameters. CONSTITUTION:A resin composition for automobile exterior furnishings is prepared by mixing a high-rigidity propylene/ethylene block copolymer (A) (ethylene content of 2-15wt.%, 1.00>=P>=0.015 logMFR+0.955(wherein P is the isotactic pentad fraction of the propylene homopolymer part and MFR is its melt flow rate)] with 5-20wt.% amorphous ethylene/propylene copolymer (B) Mooney viscosity ML1+4 (100 deg.C) <=30), 5-20wt.% amorphous ethylene/propylene copolymer (C) (Mooney viscosity ML1+4 (100 deg.C) of 50-100), 10-15wt.% talc (D) (mean particle diameter <=3mum) and 5-20wt.% calcium carbonate (E) (mean particle diameter <=5/m). It is necessary that the total of components B and C is 10-30wt.%, and the total of components of D and E is at most 30wt.%.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a resin composition for automobile exterior parts, and more specifically, to a resin composition based on high-rigidity block polypropylene, to which two types of non-containing resin compositions having a specific Mooney viscosity are applied. The present invention relates to a resin composition containing a crystalline ethylene-propylene copolymer, calcium carbonate having a specific particle size, and talc in predetermined amounts.

By molding this resin composition using a known method, the rigidity (
It is possible to obtain automobile exterior parts such as automobile bumpers, fascias, fenders, etc., which are excellent in bending elastic modulus), high temperature rigidity (heat sag), and paintability, and also have a good molded product appearance (flow mark, tiger cub mark).

(Prior Art) In recent years, polypropylene resin compositions have been used as constituent materials for automobile bumpers. Among them, resin compositions for automobile exterior parts with excellent impact resistance and rigidity are currently available.
Japanese Patent Publication No. 61-43650 and Japanese Patent Publication No. 60-3186
A polypropylene resin composition for automobile bumpers, which is a mixture of crystalline polypropylene, a non-grade ethylene-propylene copolymer, and talc, as disclosed in Japanese Patent No. 8, has been put into practical use.

(Problems to be Solved by the Invention) However, the flexural modulus of the molded product molded using the resin composition is 10,000 to 12,000 kgf/cm.
”, and it cannot be said that rigidity, especially high-temperature rigidity, is still sufficient. Automotive exterior parts need to have increased tension rigidity in order not to impair the sense of security of the vehicle.Tension rigidity greatly depends on the shape of the part. It depends, but the bending modulus is 1
It is necessary to increase it to 5,000 kgf/cm" or more.

Further, when some of the exterior parts of an automobile are made of resin, unless the steel plate is painted at the same time, the productability of the vehicle will be significantly impaired. In other words, unless the same paint is used for the steel plate, the paint color will change over time and it will likely appear as if a different paint has been applied over time. Therefore, online simultaneous painting of automobile exterior panels is desired, but currently, the coating conditions for automobile exterior panels are acrylic melamine paint, and the baking temperature is as high as 140-'C, so conventional resin compositions cannot be used. It was said that online painting was difficult for materials due to their low heat resistance. This baking is done at a temperature of 14
In order to be able to coat resin without producing defective products at 0°C, taking into account productivity, the heat sag value must be at least 3.
It needs to be no larger than the body, preferably no larger than two cabinets.

In addition, it goes without saying that automotive exterior parts must have excellent impact resistance from the standpoint of vehicle safety. The plastic strain energy is required to be at least 12 units.

In order to solve these problems, it is necessary to use a propylene resin with even better heat resistance and to fill the resin with an inorganic filler such as talc. However, if we try to solve this problem by changing only the amount of talc filled, a flow mark in the form of a tiger cub mark will appear on the surface of the molded product, and since this tiger cub mark will not disappear even after painting, the commercial value of the molded product will increase. This is not preferable because it lowers the

(Means for Solving the Problems) As a result of intensive research in order to solve these problems, the present inventors have found that, in place of the conventional crystalline propylene-ethylene block copolymer, the stereoregularity of the propylene homopolymer moiety is We use a high-rigidity propylene-ethylene block copolymer that has improved heat resistance by increasing its properties, and then we add two types of non-grade ethylene-propylene copolymers with a specific Mooney viscosity and a specific particle size. By incorporating predetermined amounts of each of calcium carbonate and talc, we have created an automotive exterior part that has superior high-temperature rigidity and paintability, and has a better appearance as a molded product, compared to automotive exterior parts such as resin bumpers that have been put into practical use to date. The present invention was completed by discovering that a resin composition for use in the present invention can be obtained.

More specifically, the resin composition for automobile exterior parts of the present invention has an ethylene content of 2 to 15% by weight, an isotactic pentad fraction (P) of a propylene homopolymer portion, and a melt flow rate (MFR). For a highly rigid propylene-ethylene block copolymer in which the relationship is expressed by the following formula 1, % (), Mooney viscosity ML, .

(100°C) 5 to 20% by weight of non-quality ethylene-propylene copolymer of 30 or less, ■Mooney viscosity tag. 4 (1
00℃) 50 to 100% amorphous ethylene-propylene copolymer 5 to 20% by weight, ■ 10 to 15% by weight of talc with an average particle size of 3 microns or less, and ■ 5 to 20% of calcium carbonate with an average particle size of 5 microns or less. % by weight, the total amount of the components (1) and (2) is 10 to 30% by weight, and the total amount of the components (2) and (2) is 30% by weight or less.

The high-rigidity propylene-ethylene block copolymer used as a base in the resin composition for automobile exterior parts of the present invention is blended in place of the conventional crystalline propylene-ethylene block copolymer for the purpose of improving rigidity, particularly high-temperature rigidity.

The highly rigid propylene-ethylene block copolymer has an ethylene content of 2 to 15% by weight and an isotactic pentad fraction (P) of the propylene homopolymer portion.
The relationship between and melt flow rate (MFR) is 1.00≧P≧0.015ffiog MFR+0.9
55...CI). In the above formula, the isotactic pentad fraction (P) is defined as the macromolecules by Zambelli (A) et al.
6925 (1973), that is, the isotactic fraction in the pentad units in the polypropylene molecular chain. In other words, the fraction is It means the fraction of propylene monomer units in which five consecutive monomer units are isotactic bonded.The method for determining peak assignment in the measurement using NMR described above is Macron+olecules 86.
87 (1975). A 270 MHz FT-NMR device was used for NMR measurements in the Examples described below.
The signal detection limit was improved to 0.001 in terms of isotactic pentad fraction by 000 integrated measurements. When a propylene-ethylene block copolymer with the fraction (P) of less than 0.955 is used,
The bending elastic modulus of the obtained molded product cannot be expected to have a sufficient improvement effect compared to the impact resistance improvement effect, and the heat sag (140'C), which is the target value for high temperature rigidity of exterior parts, is larger than 3 mm, and online The amount of deformation during painting becomes large, which is not preferable. Such a copolymer and its manufacturing method are described, for example, in Japanese Patent Application Laid-Open No. 58-201816. The highly rigid propylene-ethylene block copolymer used in the present invention described in the same publication has various strengths and heat distortion temperatures higher than conventional propylene homopolymers or crystalline propylene-ethylene block copolymers. is excellent.

However, the isotactic pentad fraction of the highly rigid propylene-ethylene block copolymer used in the present invention (
Regarding P), even if the above formula is not satisfied by itself, even if a mixture of two or more types is used, it is sufficient that the physical properties of the mixture satisfy the above formula.

Furthermore, the melt flow rate of the highly rigid propylene-ethylene block copolymer is preferably 1 to 50 g/10 m1n; if it is less than 1 g/10 sin, the molding processability will decrease, and if it exceeds 50 g/10 m1n, the molded product will have poor durability. This is not preferable because impact resistance decreases.

For the amorphous ethylene-propylene copolymer used in the present invention, two types having a gap in Mooney viscosity ML+, a (100°C) are blended in predetermined amounts.

One of them has a viscosity of 30 or less (hereinafter referred to as EPR).
-A), which is blended in a predetermined amount for the purpose of improving impact resistance and gloss, and the other has a viscosity of 50 to 100 (hereinafter referred to as EPR-B), which improves impact resistance. and is blended with the purpose of improving paintability. Incorporation of a non-quality ethylene-propylene copolymer having a viscosity outside the above Mooney viscosity range into a composition brings about the following drawbacks. That is, the viscosity is 30
If the ratio exceeds 50 but is less than 50, the balance between the glossiness and paintability of the molded article will be lost, and one or the other will tend to drop significantly.

On the other hand, if the viscosity exceeds 100, the compatibility with the high-rigidity propylene-ethylene block copolymer will deteriorate, making uniform mixing and dispersion difficult, and tiger cub marks are likely to occur, which is not preferable.

The amount of EPR-A used in the present invention is 5 to 20% by weight.
and preferably 8 to 18% by weight. If the amount of EPR-B is less than 5%, it is not preferable because the amount of EPR-B increases and the gloss rate decreases.
On the other hand, if it is added in excess of 0% by weight, f! This is not preferable because the amount of PR-8 to be blended decreases, resulting in a decrease in paintability. Further, the blending amount of EPR-H is 5 to 20% by weight, preferably 5 to 10% by weight. If the amount of EPR-8 is less than 5% by weight, the effect of improving paintability is small;
If the amount exceeds 20% by weight, the gloss of the molded product will decrease, the paint clarity will be poor, and tiger cub marks will likely occur, which is not preferred.

The total amount of EPR-A and EPR-8 having the two types of Mooney viscosities used in the present invention is 10 to 30% by weight, preferably 15 to 25% by weight.

If the total blending amount of BPR-A and EPR-B is less than 10% by weight, the impact resistance improvement effect will be small, and if the blending amount exceeds 30% by weight, a tiger cub mark will appear, so it is preferable.
It's not right.

Further, a predetermined amount of talc having an average particle diameter of 3 microns or less, preferably 2.5 microns or less is added to the composition of the present invention for the purpose of improving rigidity. If talc exceeding 3 microns is blended, it is not preferable because it reduces impact resistance, especially surface impact resistance (high-speed surface impact). In addition, the amount of talc added is 1
0 to 15% by weight, the amount of talc added is 10% by weight
If it is less than 15.000 kgf/cm, the stiffness improvement effect is not sufficient, and the flexural modulus, which is the target value of this resin composition, is 15.000 kgf/cm.
It is difficult to exceed 15% by weight, and if it is added in excess of 15% by weight, a tiger cub mark may be observed and the impact resistance will be reduced, which is undesirable. It is also useful for reducing the size and increasing dimensional stability.

Calcium carbonate used in the present invention is blended in a predetermined amount for the purpose of improving rigidity without reducing impact resistance or deteriorating the appearance of the molded product.

In other words, as mentioned above, talc is useful for improving the rigidity of molded products, but a high content of talc can worsen the appearance of molded products and reduce impact resistance.
It is undesirable to mix more than 1% by weight, whereas calcium carbonate can improve the rigidity without deteriorating the appearance of the molded product or reducing the impact resistance. Further, the average particle size of the calcium carbonate is 5 microns or less, preferably 3 microns or less. If calcium carbonate exceeding 5 microns is blended, it is not preferable because it lowers the impact resistance. Further, the amount of calcium carbonate added is 5 to 20% by weight, preferably 10-20% by weight.
It is 15% by weight. If the amount of calcium carbonate is less than 5% by weight, the stiffness improvement effect is insufficient, and if it is more than 20% by weight, the total amount of talc and calcium carbonate as an inorganic filler amount exceeds 30% by weight. This is not preferable because it deteriorates the appearance of the molded product.

The total blending amount of talc and calcium carbonate used in the present invention is 30% by weight or less, and if it is blended in excess of this, a tiger cub mark will appear on the molded product, which is undesirable.

In the composition of the present invention, antioxidants, antistatic agents, colorants, ultraviolet absorbers, slip agents, nucleating agents, plasticizers, etc. may be added as necessary to the extent that the effects of the present invention are not impaired. One or more types of additives such as additives, extender oil species additives for EPDFI, etc. can be blended.

The method for producing the composition of the present invention includes a highly rigid propylene-ethylene block copolymer, an amorphous ethylene-propylene copolymer, talc with an average particle size of 3 microns or less, and calcium carbonate with an average particle size of 5 microns or less. After stirring and mixing a predetermined amount and a predetermined amount of one or more of the above-mentioned various additives using a ribbon blender, tumbler mixer, Hensel mixer (trade name), super mixer, etc., the mixture is rolled and extruded using a Banbury mixer 1. The melting temperature is 150°C to 300'C, preferably 180°C to 250'C.
A method of melt-kneading and pelletizing at °C can be exemplified.

The thus obtained resin composition for automobile exterior parts of the present invention can be used to produce various molded products by various molding methods such as injection molding, extrusion molding, vacuum forming, and pressure forming.

(Example) Hereinafter, the present invention will be specifically explained using production examples, examples, and comparative examples of a highly rigid propylene-ethylene block copolymer (A), but the present invention is not limited thereto.

The ingredients and evaluation methods used in Examples and Comparative Examples are as follows.

Group I1 Production method of highly rigid propylene-ethylene block copolymer (A) (1) Preparation of catalyst 600 gml of n-hexane, 0.50 mol of diethylaluminum monochloride (DI!AC), 1.20 mol of diisoamyl ether. The mixture was mixed at 25° C. for 5 minutes and reacted at the same temperature to obtain a reaction product liquid (V) (molar ratio of diisoamyl ether/DEAC of 2.4). 4.0 mol of titanium tetrachloride was placed in a reactor purged with nitrogen, heated to 35°C, and the entire amount of the reaction product solution (V) was added dropwise to this over 180 minutes, kept at the same temperature for 30 minutes, and heated to 35°C. The temperature was raised to ℃ and reacted for another hour, cooled to room temperature (20℃), the supernatant liquid was removed, and n-hexane 4000+/! The operation of adding and removing the supernatant liquid by decantation was repeated four times to obtain 190 g of solid product (II). The total amount of this solid product (n) is 3000 mJ of n-hexane! 160 g of diisoamyl ether at 20"C in suspension in
and 350 g of titanium tetrachloride at room temperature for about 1 minute.
The reaction was carried out at 5°C for 1 hour. After the reaction was completed, it was cooled to room temperature, and the supernatant liquid was removed with decanethisilane.
000s+f of n-hexane was added, stirred for 10 minutes, allowed to stand, and the supernatant liquid removed. After repeating this operation five times, the mixture was dried under reduced pressure to obtain a solid product (I[[).

(2) Preparation of preactivated catalyst After purging a stainless steel reactor with inclined vanes with a volume of 201 cm with nitrogen gas, 152 g of n-hexane and 42 g of diethyl aluminum monochloride were produced as solid products (DI).
After adding 30 g of hydrogen at room temperature, 15N2 of hydrogen was added and the reaction was carried out for 5 minutes at a propylene partial pressure of 5 kg/cya"G. Unreacted propylene, hydrogen and n-hexane were removed under reduced pressure, and the preactivated catalyst (Vl) was obtained in powder form (82.0 g of propylene reacted per Ig of solid product (III)).

(3) Polymerization method 250E of n-hexane was dried in a stainless steel polymerization vessel with an internal volume of 400 Il and equipped with a turbine-type stirring blade, which was purged with nitrogen gas, followed by 1 portion of diethylaluminum monochloride.
0 g, 10 g of the preactivated catalyst (VI) and P-
) 11.0 g of methyl ruylate was charged, and hydrogen was further added to maintain a concentration of 11 mol % in the gas phase. Then, after raising the temperature inside the vessel to 70°C, propylene was supplied into the vessel, and the pressure inside the vessel was increased to 10kg/cw"G.Then, the temperature was raised to 70°C, and the pressure was 10kg/cae.
After continuing polymerization for 4 hours while maintaining the temperature at A propylene homopolymer powder was obtained.

After releasing unreacted bu-robylene, the temperature inside the polymerization vessel was maintained at 60°C and the pressure was 0.1 kg/c@''G, and the supply ratio of ethylene was 33% by weight as the raw material for the second stage polymerization. Ethylene and propylene were continuously supplied for 2 hours so that the total amount of ethylene supplied was 5.4 kg.After polymerization for 2 hours, the supply of ethylene and propylene was stopped, and unreacted ethylene and propylene were Then, 251 ml of methanol was supplied into the polymerization vessel, and the temperature was raised to 75°C. After 30 minutes, 100 g of a 20% by weight aqueous sodium hydroxide solution was added, and the mixture was stirred for 20 minutes, and pure water was added. After adding 1001, the remaining propylene was discharged.After the aqueous layer was extracted, pure water of 1001 was further added, stirred and washed with water for 10 minutes, the aqueous layer was extracted, and the highly rigid propylene-ethylene block copolymer (A)
The -n-hexane slurry was extracted, the slurry was filtered, and the filtrate was dried to obtain a white highly rigid propylene-ethylene block copolymer (A) powder.

(Ingredients) (1) Highly rigid propylene-ethylene block copolymer (
A), manufactured by Chisso Petrochemical ■, ethylene content 8% by weight,
Highly rigid propylene-ethylene block copolymer (2) with an isotactic pentad fraction of 0.980 and a melt flow rate of 25 g/10n+in! Properties Propylene-ethylene block copolymer (B), manufactured by Chisso Petrochemical ■, crystalline propylene with ethylene content of 12% by weight, isotactic pentad fraction of 0.947, and melt flow rate of 5 g/10 sin. Ethylene block copolymer (3) Amorphous ethylene-propylene copolymer 11! PR-A, manufactured by Japan Synthetic Rubber ■, propylene content 50% by weight, Mooney viscosity MLI-4 (100°C
)27(4) Amorphous ethylene-propylene copolymer EP
R-8, manufactured by Japan Synthetic Rubber ■, propylene content 21% by weight, Mooney viscosity MLI +4 (100°C) 70 (5
) Talc (C) Average particle size 2.5 microns (6) Talc (D) Average particle size 4.5 microns (7) Calcium carbonate average particle size 1.8 microns (evaluation method) (1) Melt flow rate (g) /lo minute); JI
Based on S K6758 (2) Bending modulus (3-point bending modulus) (kgf/c
m2); JIS K? Compliant with 203 (3) High-speed surface impact test A high-speed surface impact test involves punching out the surface of a fixed test piece while maintaining a constant speed, and measuring the energy required at the time of destruction using a sensor built into the test piece. , the energy after the elastic region is calculated as plastic strain energy.

Measurement conditions: Sustainability speed: 5 m/sec Refill diameter: approx. 1.6 cm (5/8 inch) Spherical holder diameter: Approx. 5 cm (2 inch) circular test piece wall thickness
3mm thickness measurement temperature -20°C (4) Molded product appearance l520OB injection molding machine (manufactured by Toshiba Machine), mold:
Injection molding was carried out under the following molding conditions: 400 x 80 x 3 mm flat plate molding temperature: 230°C, mold temperature: 30°C, gate diameter: 1.5 mm, and the appearance of the resulting flat plate was visually judged, and the flow mark (tiger cub mark) was determined. ) was not noticeable, the molded product was considered to have a good appearance.

Evaluation criteria O: Tiger cub mark is not conspicuous ×: Tiger cub mark is conspicuous (5) Heat drooping property (+nm) Using a test piece of 150 x 25 x 3 mm, 140
The amount of sag was measured at a hang distance of 50 millimeters under conditions of °C.

(6) Paintability (kg f/CI) Paintability was evaluated by measuring the coating film beer strength. That is, the surface of the test piece was cleaned by contacting the test piece with trichloroethane vapor for 30 seconds, and then a two-component acrylic-chlorinated polypropylene undercoat (manufactured by Nippon Bee Chemical) was applied to the film thickness. It was coated to a thickness of 30 to 40 microns, dried at 120°C for 10 minutes, and then left at room temperature for 10 minutes. After that, a two-component acrylic-urethane top coat (manufactured by Nippon Bee Chemical) was applied to a film thickness of 30 to 40 microns.
After drying for a minute with Cl2O, the coated product was left at room temperature for 48 hours.

Two incisions are made in the coating film of this coated product at an interval of 1 cm using an NT cutter. The edge of the coating film cut with IC1 width was partially peeled off in advance, and it was pulled in a 180 degree direction at a speed of 10a/a+in using a tensile tester to measure the peeling strength of the coating film at a width of 1cm.

1-4' 1-6 As Example 1, the above-mentioned high-rigidity propylene-ethylene copolymer ASEPR-^, II! PR-B and Talc C
and calcium carbonate were stirred and mixed for 3 minutes using a Hensel mixer (trade name) at the blending ratios listed in Table 1 below, followed by melt-kneading, extrusion, and pelletization.

In Example 2, in addition to what was blended in Example 1, crystalline propylene-ethylene block copolymer B was blended. At this time, the P fraction value of Example 2 is 0.975,
The calculated value of the bisection ratio obtained from the relational expression (1) is 0.974, which satisfies the relational expression (1). Examples 3 and 4 were carried out in accordance with Example 1 using the blending ratios shown in Table 1.

Similarly, in Comparative Examples 1 to 6, in Comparative Example 1, the high-rigidity propylene-ethylene block copolymer was not blended,
A normal crystalline propylene-ethylene block copolymer was blended, and in Comparative Example 2, only EPR-B was blended, and in Comparative Example 3, only talc was blended as EPR with EPR-A as an inorganic filler. In addition, in Comparative Example 6, talc D
The formulation was carried out in accordance with Kaba Example.

MF using the pellets obtained in each example and each comparative example.
Measurement of H and predetermined test pieces were molded by injection molding at a molding temperature of 230° C. and a mold temperature of 40° C., and flexural modulus, high-speed impact test, and thermal sag were measured. Furthermore, a molded article was formed using the obtained pellet, and the appearance and paintability of the obtained molded article were evaluated. The results are summarized in Table 1.

(Effects of the Invention) As is clear from Table 1, molded products using the composition of the present invention have higher rigidity, especially high temperature rigidity, and coating strength, compared to resin compositions for automobile exterior parts that are currently in practical use. Excellent film adhesion and molded product appearance. On the other hand, Comparative Example 1, in which a crystalline propylene-ethylene block copolymer with a low P fraction value was blended, was able to maintain the flexural modulus of 15,000 kgf/cm or more, which is the target value of the present invention. It is not possible to do so, and the thermal sagging property is also 3- or higher, which is not preferable.In Comparative Example 2, in which only EPR-B, which has a high Mooney viscosity, was blended,
Flow marks are observed on the exterior of the molded product and are visible even after painting, which is undesirable because it significantly reduces the product value. Comparative Example 3, in which only EPR-A and talc were blended, is not preferred because it is inferior in rigidity and coating adhesion, which are the objectives of improving the resin composition. In addition, in Comparative Example 4.6, in which the amount of talc added exceeds 15% by weight or the average particle size exceeds 3 microns, the appearance of the molded product deteriorates and the impact resistance decreases. Therefore, none of them are practical as materials for automobile exterior parts. Furthermore, in Comparative Example 5, in which the amount of talc added is less than 10% by weight, the rigidity is low and the thermal sagging property is also greater than the target value of 3,000 yen, making online painting impossible and impractical.

Patent applicant: Nissan Motor Co., Ltd.

Claims (1)

[Claims] 1. [1] Isotactic pentad fraction (P
) and melt flow rate (MRF) are expressed by the following formula: 1.00≧P
≧0.015logMFR+0.955...(I) A high-rigidity propylene-ethylene block copolymer having the relationship expressed by: [2] Mooney viscosity ML_1_+_4 (100°C) 30
5 to 20% by weight of the following amorphous ethylene-propylene copolymer, [3] Mooney viscosity ML_1_+_4 (100°C) 50
~100 amorphous ethylene-propylene copolymer 5-2
0% by weight, [4] 10-15% by weight of talc with an average particle size of 3 microns or less, and [5] 5-5% of calcium carbonate with an average particle size of 5 microns or less.
20% by weight, the total amount of components [2] and [3] is 10 to 30% by weight, and the total amount of components [4] and [5] is 30% by weight or less. Resin compositions for automotive exterior parts.