JPH0463100B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a resin composition for automobile bumpers that has excellent impact resistance, rigidity, moldability, and paintability. [Prior Art] Crystalline polypropylene has excellent properties in terms of rigidity, heat resistance, gloss, etc., but it has poor impact strength and paintability, so when used for automobile bumpers,
A method has been proposed in which a rubber-like substance such as polyethylene, polyisobutylene, polybutadiene, or amorphous ethylene/propylene copolymer is mixed with this. In order to improve the decrease in rigidity caused by the addition of these rubbery substances, it has also been proposed to add and mix inorganic fillers such as talc. As such a method, for example, when the ethylene content is 5
~10 parts by weight, crystalline ethylene-propylene block copolymer with MFR of 2-10 g/10 minutes, amorphous ethylene-propylene copolymer with intrinsic viscosity of 2.0-3.5 dl/g, and polypropylene composition for talc or bumper. (Japanese Unexamined Patent Publication No. 57-55952) or a polypropylene composition further containing high-density polyethylene (Japanese Unexamined Patent Publication No. 57-159841) have been proposed; however, the former composition is the main component. Since the ethylene content of the ethylene-propylene block copolymer is low and the MFR is also low, it has the drawbacks of insufficient impact resistance and poor moldability. On the other hand, the latter composition was designed to improve the insufficient impact resistance due to the low ethylene content of the ethylene-propylene block copolymer, which is the main component, by adding high-density polyethylene. Such post-addition of high-density polyethylene often causes poor dispersion, and as a result, there is a risk that the paintability of the molded product will deteriorate. At present, it is difficult to obtain polypropylene compositions for automobile bumpers that have well-balanced properties. [Means Adopted to Solve the Problem] In view of the above circumstances, the present inventor conducted various studies in order to obtain a polypropylene composition for automobile bumpers that has a well-balanced impact resistance, rigidity, paintability, moldability, etc., and found a specific It has been found that a resin composition comprising a propylene/ethylene block copolymer, an ethylene/α-olefin indum copolymer, and talc can achieve the object of the present invention, and the present invention has been completed. That is, according to the present invention, crystalline propylene/ethylene block copolymer component (A); 50 to 75 parts by weight; amorphous ethylene/α-olefin random copolymer component (B); 15 to 40 parts by weight. and talc component
(C): 1 to 25 parts by weight (here, the total amount of each component (A), (B), and (C) is selected to be 100 parts by weight); a melt of the above (A) component; The flow rate (MFR) is
25 to 60 g/10 minutes, the ethylene unit content is 5 to 14 mol%, and the (A) component is each component (A-1), (A-2) and (A-3), (A-1 ): Polypropylene component, (A-2): Ethylene unit content is 42 to 46 mol%,
The intrinsic viscosity measured at 135°C in Delican solvent is
Consists of 1.5 to 3 dl/g of ethylene/propylene random copolymer component, (A-3): polyethylene component with propylene unit content of 10 mol% or less, and the proportions of these are 74 to 3 dl/g, respectively.
88% by weight, 10 to 14% by weight, and 2 to 10
% by weight, and the ethylene content of the component (B) is 60 to 85 mol%. [Aspects of the invention] The crystalline propylene/ethylene block copolymer component (A) used in the present invention has an ethylene unit content of 5
to 14 mol%, preferably 9 to 13 mol%, melt flow rate (MFR: ASTM D1238, condition L) 25 to 60 g/10 min, preferably 30 to 13 mol%.
45g/10min block copolymer. This copolymer component (A) is a polypropylene component (A-
1) 74 to 88% by weight, preferably 80 to 86% by weight, ethylene-propylene random copolymer component (A-2) 11 to 14% by weight, propylene unit content 10
mol% or less, preferably 5 mol% or less of polyethylene component (A-3) 2 to 10% by weight, preferably 3
~6% by weight. The isotactic index (II) of the polypropylene component (A-1) is preferably 95% or more. Here, the isotactic index is C ¹³ −
This is the triad tacticity fraction measured by NMR method. This polypropylene component (A-
1) is a propylene homopolymer or 2 mol% or less,
Preferably, it is a propylene/ethylene copolymer whose main component is propylene in which 1 mol % or less of ethylene is randomly copolymerized. The ethylene unit content of the ethylene/propylene random copolymer component (A-2) is 42 to 46 mol%, and the intrinsic viscosity [η] measured at 135°C in a decalin solvent is 1.5 to 3 dl/g, preferably 2 to 3 dl/g.
3 dl/g copolymer. Intrinsic viscosity of polyethylene component (A-3) [η]
is usually 2 to 5 dl/g, preferably 3 to 4.5 dl/g. The propylene/ethylene block copolymer component (A) is produced by polymerizing olefins in one polymerization reaction system in the presence of a stereoregular catalyst, preferably a catalyst comprising a supported transition metal component and an organoaluminum compound. It is a so-called non-polymer blend type copolymer obtained by this method, and a specific method for producing such a propylene/ethylene block copolymer (A) is described in JP-A-52-98045 and JP-B-Sho 57-26613. Familiar with issues and publications. The propylene/ethylene block copolymer component (A) used in the present invention is not necessarily limited to one type of polymer obtained by polymerizing in one polymerization reaction system, but rather two or more types of propylene/ethylene block copolymer components polymerized separately.
It may be a mixture of ethylene block copolymers, but in that case the ethylene unit content and MFR of the mixture must be within the above ranges. The ethylene content in the present invention is ¹³ C-NMR
This is the value measured by the method. The amorphous ethylene/α-olefin random copolymer component (B) used in the present invention has an ethylene content of
60 to 85 mol%, especially 75 to 82 mol%,
Melt flow rate (MFR: ASTM D 1238,
It is preferred that L) is usually 0.1 to 5 g/10 min, particularly 0.2 to 4 g/10 min, and the crystallinity by X-rays is 20% or less, especially 10% or less. Those with an ethylene content of more than 85 mol% and those with a degree of crystallinity of more than 20% have little impact resistance improvement effect, and those with an ethylene content of less than 60 mol% have poor melt fluidity and are difficult to mold. If the melt flow rate exceeds 5 g/10 minutes, the effect of improving impact resistance tends to be poor. Specific examples of the α-olefin include propylene, 1-butene, 1-hexene, and 4-olefin.
Examples include methyl-1-pentene. The copolymer component (B) also contains a small amount of diene monomer, such as dicyclopentadiene, ethylidene norbornene,
1,4-hexadiene or the like may be copolymerized. The ethylene/α-olefin random copolymer component (B) is usually produced using a combined catalyst of a vanadium compound and an organoaluminium compound.
Specifically, for example, using hexane as a solvent,
Vanadium oxytrichloride is added to this, then a mixed gas of ethylene and α-olefin is dissolved and saturated, and then a solution of ethylaluminum sesquichloride dissolved in hexane is added to carry out polymerization. Can be manufactured. The talc component (C) used in the present invention is usually commercially available as an inorganic filler, and preferably has an average particle size of 0.5 to 5μ, more preferably 1 to 4μ. If the average particle size exceeds 5μ, the mechanical strength may decrease, while if the average particle size is less than 0.5μ, poor dispersion may occur during kneading. The talc component (C) may be untreated, but in order to improve its affinity with the propylene/ethylene block copolymer component (A), organic titanate coupling agents, silane coupling agents, It may be treated with carboxylic acid-modified polyolefin or the like or used in combination with them. The resin composition of the present invention comprises the propylene/ethylene block copolymer component (A); 50 to 75 parts by weight, preferably 55 to 65 parts by weight, ethylene/α
-Olefin-in-radham copolymer component (B); 15 to 40
parts by weight, preferably 20 to 30 parts by weight, and talc component (C); 1 to 25 parts by weight, preferably 10 to 30 parts by weight;
Consisting of 20 parts by weight. Here, the blending amounts are selected so that the total amount of each component (A), (B), and (C) is 100 parts by weight. Moreover, the resin composition for automobile bumpers of the present invention
The MFR is preferably adjusted to 15 g/10 minutes or more, particularly 15 to 30 g/10 minutes. Propylene/ethylene block copolymer component (A)
If the amount is less than 50 parts by weight, the rigidity is poor;
If it exceeds 75 parts by weight, paintability and impact resistance will be poor. If the amount of talc component (C) is less than 1 part by weight, the rigidity will not be improved, while if it exceeds 25 parts by weight, the product will become brittle and the impact resistance will decrease. In the composition of the present invention, the crystalline propylene/ethylene block copolymer component (A) is composed of the ethylene/α-olefin random copolymer component (B) and the talc component.
(C) in the above range, for example, using a Henschel mixer, V
- After mixing with a blender, ribbon blender, tumbler blender, etc., use a single screw extruder, multi-screw extruder,
It is obtained by melt-kneading with a kneader, Banbury mixer, etc. Among them, by using equipment with excellent kneading performance such as a multi-screw extruder, kneader, Banbury mixer, etc., a high quality resin composition for automobile bumpers in which each component is more uniformly dispersed can be obtained. In addition to antioxidants, UV absorbers, lubricants, nucleating agents, antistatic agents, flame retardants, pigments, dyes or talc, the compositions of the present invention may contain other inorganic or organic compounds at any stage of their mixing. Various fillers such as fillers and reinforcing agents can be blended within the range that does not impair the purpose of the present invention. [Industrial Utility] The resin composition for automobile bumpers of the present invention has excellent melt flowability, that is, excellent processability, and the bumper obtained by injection molding has good impact resistance, low-temperature impact resistance, and rigidity. It has excellent dimensional stability and also excellent paintability, so it is suitable for use in automobile bumpers. [Examples] Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded. Example 1 60 parts by weight of propylene/ethylene block copolymer PB-I listed in Table 1, ethylene content 82 mol%,
MFRO0.7g/10min, ethylene with crystallinity 5%.
Propylene random copolymer (hereinafter abbreviated as EPR)
25 parts by weight and 15 parts by weight of talc, 1 part by weight of carbon black and a heat-resistant stabilizer (trade name Yoshinox BHT manufactured by Yoshitomi Pharmaceutical Co., Ltd.: 0.1 part by weight, Irganox 1010 manufactured by Musashino Gaiki Co., Ltd.: 0.1 part by weight). After mixing with a Henschel mixer, the mixture was granulated using a twin-screw extruder (ZSK53L manufactured by Werner & Pfleiderer) at a resin temperature of 220°C to obtain a composition. Next, the composition was molded into an injection molding machine (Dynamelter).
A test piece was molded at a resin temperature of 200℃ using SJ-45C, mold clamping force 1410TON (manufactured by Meiki Seisakusho Co., Ltd.), and a separate mock bumper mold (length 460mm x width 120mm) was used.
mm
400TON (manufactured by Japan Steel Works, Ltd.)) to control the resin temperature.
200℃, injection pressure 800Kg/cm ² (primary), 500Kg/cm ²
(Secondary) A mock bumper was molded under conditions of an injection speed of 24 mm/sec, and its appearance (presence or absence of flow marks) was inspected. The test results are shown in Table 2. Evaluations other than appearance were performed in the following manner. MFR: ASTM D 1238L (g/10 min) Initial bending modulus: ASTM D 790 (Kg/cm ² ) Izot impact strength: ASMT D 256-30℃
(Kg・cm/cm) Low temperature embrittlement temperature: ASTM D 746 (°C) Examples 2 to 3 and Comparative Examples 1 to 2 Propylene/ethylene block copolymers PEB- to PEB-V listed in Table 1, Example 1 The same procedure as in Example 1 was conducted except that EPR and talc were used in the proportions shown in Table 2. The results are shown in Table 2.

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Claims (1)

[Claims] 1. Crystalline propylene/ethylene block copolymer component (A); 50 to 75 parts by weight, amorphous ethylene/ethylene block copolymer component (A);
It consists of α-olefin random copolymer component (B); 15 to 40 parts by weight and talc component (C); 1 to 25 parts by weight (here, the total of each component (A), (B), and (C)). (The amount is selected to be 100 parts by weight), and the melt flow rate (MFR) of component (A) above is
25 to 60 g/10 minutes, the ethylene unit content is 5 to 14 mol%, and component (A) is each of the following components (A-1), (A-2), and (A-3), (A- 1): Polypropylene component, (A-2): Ethylene unit content is 42 to 46 mol%,
The intrinsic viscosity measured at 135°C in Delican solvent is
Consists of 1.5 to 3 dl/g of ethylene/propylene random copolymer component, (A-3): polyethylene component with propylene unit content of 10 mol% or less, and the proportions of these are 74 to 3 dl/g, respectively.
88% by weight, 11 to 14% by weight, and 2 to 10% by weight, and the ethylene content of the component (B) is 60 to 85% by mole, a resin composition for an automobile bumper.