JPS6343942A - Resin composition for automobile bumper - Google Patents

Abstract

PURPOSE:To provide the title compsn. which has excellent melt flow characteristics and gives a bumper having excellent impact resistance, rigidity, dimensional stability and coatability, consisting of a specified crystalline propylene/ethylene block copolymer, a non-crystalline ethylene/alpha-olefin random copolymer and talc. CONSTITUTION:74-88wt% PP component (a) is blended with 10-16wt% ethylene/propylene random copolymer component (b) having an ethylene unit content of 40-50mol% and an intrinsic viscosity of 1.5-3dl/g (in decalin at 135 deg.C) and 2-10wt% PE component (c) having a propylene unit content of not higher than 10mol% to obtain a crystalline propylene/ethylene block copolymer component (A) having an ethylene unit content of 5-14mol% and an MFR of 25-60g/10min. 50-70pts.wt. component A is blended with 15-40pts.wt. non- crystalline ethylene-alpha-olefin random copolymer (B) having an ethylene content of 60-85mol%, an MFR of 0.1-5g/10min and an X-ray crystallinity of not higher than 20% and 1-25pts.wt. talc (c) having an average particle size of 0.5-5mu in such a proportion that the total amount is 100pts.wt., thus obtaining the title compsn. having an MFR of not lower than 15g/10min.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin composition for automobile bumpers that has excellent impact resistance, rigidity, moldability, and paintability.

[Prior Art 1 Crystalline polypropylene has excellent properties in terms of rigidity, heat resistance, gloss, etc., but it has poor impact strength and paintability.
When used in automobile bumpers, polyethylene, polyisobutylene, polybutanoene, amorphous ethylene, etc.
A method of mixing a rubbery substance such as a propylene copolymer has been proposed.

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 a non-charging agent such as talc.

As such a method, for example, crystalline ethylene with an ethylene content of 5 to 10% by weight and an MFR of 2 to 10 g/10 min.
Propylene block copolymer, intrinsic viscosity 2.0-3
, 5 dl/g of a polypropylene composition for bumpers consisting of an amorphous ethylene-propylene copolymer and talc (
Special I period No. 57-55952 No. 1ll) or polypropylene compositions further containing high-density polyethylene (Japanese Patent Laid-Open No. 57-159841) have been proposed, but the former composition is the main component. The ethylene content of the ethylene-propylene block copolymer is low, and the MF
Since R is also small, it has the drawbacks of insufficient impact resistance and poor moldability. On the other hand, in the latter composition, the insufficient impact resistance due to the low ethylene content of the ethylene-propylene block copolymer, which is the main component, was improved by adding high-density polyethylene. Such post-addition of high-density polyethylene often causes poor dispersion, which may lead to a decrease in the paintability of the molded product. At present, it is difficult to obtain polypropylene compositions for automobile bumpers that have well-balanced moldability and other 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 Propylene/ethylene block copolymer, ethylene/α
- It has been found that a resin composition comprising an olefin languum copolymer and talc can achieve the objects 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
25 parts by weight (where (A), (B))
and the total amount of each component (C) is selected to be 100 parts by weight), and the melt flow rate (MFR) of the component (A) is 25
60g/10min, ethylene unit content 5 to 1
4 mol%, and component (A) is the following (A-1), (A-2) and (
Each component of A-3), (A-1): Polypropylene component, (A-2): Ethylene unit content is 40 to 50 mol%, and the intrinsic viscosity measured at 135°C in decalin solvent is 1.5 to 50%. 3 dl/g of an ethylene-propylene random copolymer component, (A-3): a polyethylene component containing propylene units of filo mol% or less, and the proportions of these are 74 to 88, respectively.
% by weight, from 10 to 16% by weight, and from V2 to 10% by weight.

[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 1 to 13 mol%, melt 70-
rate (MFR: ASTM D1238, condition L) of 25 to 60E/10 minutes, preferably 30 to 45
g/10 min block copolymer. And this copolymer component (A) is polypropylene component (A-1) 74
to 88% by weight, preferably 80 to 86% by weight, ethylene/propylene random copolymer component (A-2) 10
polyethylene component (A-3) with an outermost pyrene unit content of 10 mol% or less, preferably 5 mol% or less, 2 to 10% by weight, preferably 3 to 6 mol%. Consists of %.

The isotactic index (II) of the polypropylene component (A-1) is preferably 95% or more.

Here, the isotactic index is the tri-7 tacticity fraction measured by C''-NMR method. This polypropylene component (1 to -1) is a propylene homopolymer or 2 mol% or less, preferably 1 It is a propylene/ethylene copolymer whose main component is propylene in which less than mol% of ethylene is randomly copolymerized.

Ethylene/propylene random copolymer component (A-2)
has an ethylene unit content of 40 to 50 mol 96, preferably 42 to 46 mol %, in decalin solvent at 135°C.
The intrinsic viscosity measured at [rll is 1°5 to 3 cl
l/g, preferably 2 to 3417 g of copolymer.

The intrinsic viscosity ['7] of the polyethylene component (A-3) is usually 2 to 5417 g, preferably 3 to 4.5 dl/g.

The above propylene/ethylene block copolymer component (A
) is a so-called non-polymer blend type obtained by polymerizing olefins in one polymerization reaction system in the presence of a stereoregular catalyst, preferably a catalyst consisting of a supported transition metal component and an organoaluminum compound. A method for producing such a propylene/ethylene block copolymer (A) is described in JP-A-52-9804.
For details, see Publication No. 5 and Special Publication No. 57'2G (Publication No. 313).

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 range.

The ethylene content in the present invention is a value measured by C-NMR method.

The amorphous ethylene/a-olefin random copolymer component (B) used in the present invention has an ethylene content of usually 60 to 85 mol%, particularly 75 to 82 mol%, and a melt 70-rate (MFR: ASTM D 1238
, L) is usually 0.1 to 5 g/10 min, especially 0.
Crystallinity by 2 to 4 g/10 min and X#a is 20
% or less, particularly preferably 10% or less. Those with an ethylene content of more than 85 mol% and 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. Poor quality, melt 70-rate 5
If it exceeds g/10 minutes, the effect of improving impact resistance tends to be poor.

Specific examples of the a-olefin include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and the like. The copolymer component (B) may also be copolymerized with a small amount of tsene monomer, such as dicyclopentanoene, ethylidenenorbornene, 1°4-hexanoene, etc.

The ethylene/a-olefin random copolymer component (
B) is usually prepared using a combination catalyst of a vanadium compound and an organoaluminum compound.

Specifically, for example, hexane is used as a solvent, vanadium oxytrichloride is added to this, and then ethylene and α-
It can be produced by dissolving and saturating a mixed gas of olefins, adding a solution of ethylaluminum sesquichloride dissolved in hexane in advance, and performing polymerization.

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 R 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), etc. It may be treated with a ring agent, a carboxylic acid-modified polyolefin, etc., or may be used in combination with them.

The resin composition of the present invention includes the propylene/ethylene block copolymer component (Δ): 50 to 75 parts by weight, preferably 55 to 65 parts by weight, the ethylene/α-olefin random copolymer component (B); 15 to 40 parts by weight, preferably 20 to 30 parts by weight, and a talc component (
C); 1 to 25 parts by weight, preferably 10 to 20 parts by weight
Consisting of 1n parts. Here (A), (B) and (
C) The blending amounts are selected so that the total amount of each component is 100 parts by weight.

Further, the MFR of the resin composition for automobile bumpers of the present invention is I
It is preferable to adjust the amount of Sg/10 minutes or more, particularly 15 to 30 g/710 minutes.

When the amount of the propylene/ethylene block copolymer component (A) is less than 50 parts by weight, the rigidity is poor;
If it exceeds 50%, the 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), the ethylene/a-olefin random copolymer component (B) and the talc component (C) are mixed in the above ranges, for example, using a Henschel mixer, ■-Plender,
After mixing with ribbon pre-goo, tumbler pre-goo, etc.
It can be obtained by melt-kneading in a single pongee extrusion, multi-pongee extrusion, Nigoo, Banbury mixer or the like. Among them, by using equipment with excellent cross-talk performance such as a multi-screw extruder, Negoo mixer, or Banbury mixer, a high quality mullium fat 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 may be added within a range that does not impair the object of the present invention.

[Industrial Utility 1] 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 It! It has excellent impact resistance, low-temperature impact resistance, rigidity, and dimensional stability, as well as excellent paintability, so it is suitable for use in automobile bumpers.

[Examples] Next, the present invention will be explained 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 Propylene/ethylene block copolymer FE listed in Table 1
B-160 parts by weight, ethylene content 82 mol%, MFRo
, 7 g/10 minutes, 25 parts by weight of ethylene-propylene random copolymer (hereinafter abbreviated as EPR) with a crystallinity of 5%, 15 parts by weight of talc, 1 part by weight of carbon black, and a heat-resistant stabilizer (trade name: Yoshinox BHT). Yoshitomi Pharmaceutical■
Manufactured by: 0.1 part by weight, Irganox 1010 Musashi/i
f Iggy f Jl: 0.1 layer IL part) in a Henschel mixer, then twin-screw extrusion n (Werner &
Pfleidcrer ZSK53L) was used to granulate the resin at a resin temperature of 220° C. to obtain a composition.

Next, the composition was molded into an injection molding machine (Dyna Nolter 5J-4
5C, mold clamping force 140TON @ name 8! A test piece was molded at a resin temperature of 200℃ using a mold manufactured by Seisakusho, and a mock bumper mold (length 460m, width 120mm, height 56mm, wheels, 1 piece on the back of the bumper and 4 lips) was prepared. Thick?
83-wheel) to another injection molding machine (N400 mold clamping force 400T)
The resin temperature was set at 200℃,
Injection pressure 800 kg/am” (primary), 500 kg
/ cm' (secondary) and an injection speed of 24 mm/see, a mock bumper was molded and its appearance (presence or absence of 70-marks) was inspected. The test results are shown in Table 2. Evaluations other than appearance were performed by the following methods.

MFR: ASTM D 1238L (g
/10 minutes) Examples 2-3 and Comparative Examples 1-2 Propylene/ethylene block copolymer PE listed in Table 1
The ponds using B-II to PEB-V, the EPR of Example 1, and talc in the proportions shown in Table 2 were prepared in the same manner as in Example 1. The results are shown in Table 2.

Claims (1)

[Claims] (1) 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), and the melt flow rate (MFR) of component (A) is 25
60g/10min, ethylene unit content 5 to 1
4 mol%, and component (A) is the following (A-1), (A-2) and (
Each component of A-3), (A-1): polypropylene component, (A-2): ethylene unit content is 40 to 50 mol%
, an ethylene-propylene random copolymer component with an intrinsic viscosity of 1.5 to 3 dl/g measured at 135°C in a decalin solvent, (A-3): a polyethylene component with a propylene unit content of 10 mol% or less, and these percentages range from 74 to 88, respectively.
% by weight, 10 to 16% by weight, and 2 to 10% by weight.