JPH01150A - Resin composition for automobile bumpers - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a resin composition for automobile bumpers.

More specifically, the present invention relates to a resin composition suitable for manufacturing an automobile bumper that has excellent impact resistance, rigidity, and paintability, and can be easily molded without generating voids or 70-marks.

[Prior Art] Crystalline polypropylene has excellent properties in terms of rigidity, heat resistance, gloss, etc., but it has poor impact resistance, especially resistance to low temperatures. The disadvantage is that the properties and paintability +'= are inferior. Therefore, its application to fields that require impact resistance and paintability, such as automobile bumpers, has been limited.

In order to improve these drawbacks of conventional crystalline polypropylene, a method has been proposed in which a rubbery substance such as polyethylene, polyisobutylene, polybutadiene, or amorphous ethylene/propylene co-i' is mixed with crystalline polypropylene. ing. 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.

For example, Japanese Patent Application Laid-open No. 57-55952 discloses that the ethylene content is 5 to 10% by weight, the melt flow rate (MFR
) is 2 to Jog/10 minutes, a crystalline ethylene/propylene block copolymer with an intrinsic viscosity of 2.0 to 3,5
A polypropylene composition for forming a bumper comprising an amorphous ethylene-propylene copolymer of dl/H and talc is disclosed, and JP-A-57-159841 discloses a polypropylene composition to which high-density polyethylene is added. Disclosed. However, JP-A-57-5595
In the polypropylene composition disclosed in Publication No. 2, the ethylene content of the ethylene/propylene block copolymer, which is the main component, is as low as 5 to iomH%, and the melt flow rate is as low as 2 to 10 g/10 min. There were problems in that the impact resistance was not sufficient and the moldability was also poor. On the other hand, the polypropylene composition disclosed in Tokusho No. 57-159841 has ethylene as the main component.
The attempt was made to improve the insufficient impact resistance of propylene block copolymers due to their low ethylene content by adding high-density polyethylene. As a result, there were problems such as poor paintability of the molded product. In order to solve such problems, the present applicant has disclosed
In Publication No. 838, (a) the ethylene content is from 15 to
35 mol% and melt flow rate 10-60g7
10 minutes propylene-ethylene block copolymer 50~
70% by weight1. rb) ethylene/a-olefin random copolymer with an ethylene content of 60 to 85 mol%, a melt flow rate of 0.1 to 2 g/10 min, and a crystallinity of 10 or less according to X#X, and 25 to 40% by weight; (e) A polypropylene composition comprising 3 to 20 1% by weight of talc is disclosed. This polypropylene composition has excellent impact resistance, rigidity, and paintability, but the ethylene component (b)
The content of a-olefin random copolymer is 25 to 40
Because of the high weight percentage, moldability is difficult, and when molded into an automobile bumper, voids or 70-marks may occur, and the appearance of the molded product is not necessarily satisfactory.

Problems to be Solved by the Invention The present invention provides an automobile bumper that has excellent impact resistance, rigidity, and paintability, and can be easily molded without producing voids or 70-marks! ! It relates to a resin composition suitable for manufacturing.

[Means for Solving the Problems 1] The above object, according to the present invention, provides (A) a crystalline propylene-ethylene block copolymer having an ethylene unit content of 10 to 30 mol% and a melt flow rate of 10 to 30 g/10 min; Coalescing (component A) 60 to 85 overlapping parts, where the above component A is (A-III) 50 to 80% by weight of a propylene polymer component having an isotactic index of 90 or more (component A-1), ( A-II) Propylene-ethylene copolymer component having an ethylene unit content of 40 to 60 mol% and an intrinsic viscosity of less than 2.0 L4.0 dl/g (A-III portion) 16
more than 20% by weight, (A-ITI) propylene unit content of 10 mol% or less, and an intrinsic viscosity of 1.0 to 10.0 dl/g
3 to 20% by weight of the ethylene copolymer component (A-III component), and the above A-1 component and A-II component A-m
The weight percent of the components is based on the total weight of these three components; (B) the ethylene unit content is from 60 to 85 mole percent;
Melt flow rate 0.1 to 5, Og/10
5 to 20 parts by weight of an amorphous ethylene/a-olefin random copolymer component (component B) with a crystallinity of 15% or less and (C) an average particle size of 0.1 to consisting of 8 to 15 parts by weight of 5 μ of talc or calcium carbonate I & Min (C component), where the parts by weight of A component, B component and ct component are selected such that their total sum is 100 parts by weight. This is achieved by a resin composition for automobile bumpers having a melt flow rate of 10 g/10 minutes or more.

The present invention will be explained in detail below.

The resin composition for an automobile bumper according to the present invention essentially comprises (A) a one-component propylene/ethylene block copolymer (
(A component), (B) an amorphous ethylene/α-olefin random copolymer component (B component), and (C) a talc or calcium carbonate component (C component).

In the present invention, the amount of component A is 60 to 85 parts by weight, preferably 70 to 80 parts by weight, based on 100 parts by weight of the total weight of components A, B, and C.

Crystalline propylene/ethylene block copolymer component (A
If the amount of component) is less than 60 parts by weight, the rigidity will be poor, while if it exceeds 85 parts by weight, the paintability and wJgl resistance will be poor.

In the present invention, the amount of component B is 5 to 20 parts by weight, preferably 8 to 15 parts by weight, based on 100 parts by weight of the total weight of components A, B, and IC.

If the amount of the amorphous ethylene/α-olefin random copolymer component (component B) exceeds 20 parts by weight, the rigidity will be poor;
If the amount is less than 1 part by weight, impact resistance and paintability are insufficient.

In the present invention, component C is 8 to 15 parts by weight, based on 100 parts by weight of the total weight of component A, component B, and component C.

If the amount of talc or calcium carbonate component (component C) is less than 8 parts by weight, the stiffness improvement effect will not be sufficient, while if it exceeds 15 parts by weight, the product will become brittle and the impact resistance will decrease.

The melt flow rate (MFR) of the resin composition for automobile bumpers of the present invention is 10 to 30 g/l.

It is preferable to adjust the amount to 15 to 25 g/10 minutes.

The melt flow rates described herein are AS
Measured according to TMD 1238 conditions.

In the present invention, component A is a block copolymer of propylene and ethylene.

In the present invention, AI & min has an ethylene unit content fi (ratio of repeating units in ethylene) of 10 to 30 mol%, preferably 18 to 28 mol%, and a melt flow rate (MFR) of 10 to 3. 0g/10
min, preferably 15 to 25 g/10 min.

In the present invention, component A essentially consists of (A-III) a propylene polymer component (component A-1), (A-It) a propylene-ethylene copolymer component (A-If acid component, and (A-If acid component). III) Ethylene copolymer component (A-1
[Ingredients].

In the present invention, the A-1 component is 50 to 80% by weight, preferably 60 to 80% by weight, based on the total weight of the A-1 component, the A-n component, and the A-[[51] component.

In the present invention, the A-II component is more than 16% by weight but less than 20% by weight based on the total weight of the A-1 component, A-n component and A-II1 component.

In the present invention, A-II1 component is A-1 component, A-n
It is 3 to 20% by weight, preferably 5 to 12 parts by weight, based on the total weight of the components and uA-II1 component.

In the present invention, A-1 is defined as Aitsu Takuchi 7 index (
I index) is 90 or more, preferably 95 or more.

Here, the intactic index is the triad toughness fraction measured by CIj-NMR method.

This propylene polymer component (component A-1) is a propylene homopolymer or a propylene/ethylene copolymer whose main component is propylene in which 2 mol% or less, preferably 1 mol% or less of ethylene is randomly copolymerized. be. .

In the present invention, the A-n component has an ethylene Jit content of 40 to 60 mol%, preferably 40 to 50 mol%, and an intrinsic viscosity of 2.0 to 4°0 dl/g, preferably 2.5 to 60 mol%. 3.5 di/g.

The intrinsic viscosity here is measured at 135°C in decalin solvent.

When the intrinsic viscosity is less than 2.0 dl/g, voids are likely to occur in the resin composition. On the other hand, the intrinsic viscosity is 4゜0cll
/g, the moldability of the resulting resin composition deteriorates and 70-marks are likely to occur.

In the present invention, component A-III has a propylene unit content of 10 mol% or less, preferably 5 mol% or less, and an intrinsic viscosity of 1.0 to 10.0 dl/g, preferably 2.0 mol% or less.
~4.5 dl/g.

In the present invention, component n is a random copolymer of ethylene and α-olefin.

Specific examples of the a-olefin include, for example.

Pyrene, 1-butene, 1-hexene, 4-methyl-1-
Examples include pentene. Further, the copolymer component (BI&MIN) may contain a small amount of diene monomer, such as round dicyclopentanoene, ethylidene norporine, 1,4-hexadiene, etc., copolymerized therein.

In the present invention, component n has an ethylene unit content of 60 to 85 mol%, preferably 75 to 82 mol%, and a melt flow rate of 0.1 to 5,0.710 minutes, preferably 0.2 to 3.

0 g/10 minutes, and the crystallinity by XuA is 15% or less, preferably 5% or less.

An n-component with an ethylene unit content exceeding 85 mol% and an n-component with a crystallinity exceeding 15% have poor compatibility with the A component, cause poor appearance of the product, and are less effective in improving impact resistance. . On the other hand, if 81 minutes with an ethylene unit content of less than 60 mol % is used, the effect of improving impact resistance in the cryogenic temperature region becomes small.

When the melt flow rate of Bt & min exceeds 5 g/10 min, the impact resistance of the resin composition is not significantly improved.

In the present invention, the C component has an average particle size of 0.1 to 5 μm.
, preferably 1 to 4μ.

If the average particle size exceeds 5μ, the mechanical strength, particularly the impact strength, of the resulting resin composition may decrease, while if the average particle size is less than 0.1μ, poor dispersion may occur during kneading. The stiffness improvement effect is also small. The talc or calcium carbonate component (component C) may be untreated, but in order to improve its affinity with the crystalline propylene/ethylene block copolymer component (component A), organic titanate-based cups are used. It may be treated with a ring agent, a silane coupling agent, a carboxylic acid-modified polyolefin, etc., or used in combination with them.

The above-mentioned crystalline propylene/ethylene block copolymer component (component A) is produced by, for example, polymerizing olefins in the presence of a stereoregular catalyst, preferably a catalyst consisting of a supported transition metal component and an organoaluminum compound. It is a so-called non-polymer blend type copolymer obtained by polymerization in a system, and a specific method for producing such a crystalline propylene/ethylene block copolymer (component A) is disclosed in Vf 1979 98045. This method is disclosed in Japanese Patent Publication No. 57-26613 and the like.

The crystalline propylene/ethylene block copolymer component (component A) used in the present invention is not necessarily limited to one type of polymer obtained by polymerizing in one polymerization reaction system,
It may be a mixture of two or more propylene/ethylene block copolymers polymerized separately, 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 a value measured by 13C-NMR method.

The amorphous ethylene/a-olefin random copolymer component (component B) is usually produced using a combination catalyst of a vananoum compound and an organic aluminum compound. Specifically, for example, hexane is used as a solvent, pananonium oxytrichloride is added thereto, then ethylene and α-olefin are mixed to dissolve and saturate the gas, and then ethylaluminum sesquichloride is dissolved in hexane in advance. The production process is carried out by adding a diluted solution and carrying out polymerization.

The talc or calcium carbonate component (component C) used in the present invention is usually commercially available as an inorganic filler.

The composition of the present invention comprises a crystalline propylene/ethylene block copolymer component (component A), an ethylene/a-olefin random copolymer component (component B), and a talc component (component B).
component C) within the above range, for example, using a Henschel mixer, V
- After mixing with 7' astragalus, ribbon blender, tumbler blender, etc., single screw extruder, multi-screw extruder, niegu,
It is obtained by melt-kneading using a Banbury mixer or the like. Among them, multi-screw extruders, Nigoo, and Banbury mixers.
By using equipment with excellent kneading performance such as the above, 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 or dyes, the compositions of the invention may contain other inorganic or organic fillers 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.

The automotive bumper resin composition of the present invention has excellent melt flowability, that is, excellent processability, and the bumper obtained by injection molding has excellent impact resistance, low-temperature impact resistance, rigidity, and dimensional stability. It also has excellent paintability! 1ib
Suitable for ItL bumpers.

The present invention will be specifically described below using examples.

The crystalline propylene/ethylene block copolymer component (component A) used in the Examples and Comparative Examples described later was
Record in the table. A1, A2, and A3 in Table 1 are within the range of the A component of the present invention, but A4 to A5 is outside the range of the A component of the present invention.

Table 2 shows the amorphous ethylene/α-olefin random copolymer components (component B) used in the Examples and Comparative Examples described below.
B3 is within the range of B I & 5) of the present invention.
is outside the range of

Table 3 lists the talc or calcium carbonate components (component C) used in the Examples and Comparative Examples described below. Third
01 and (/C2 in the table are within the range of the C component of the present invention, but C3 is outside the range of the C component of the present invention.

Pt52 Table: Amorphous ethylene α-olefin Langum copolymer component (B component) used in Examples and Comparative Examples Table 3: Talc and calcium carbonate components (C component) used in Examples and Comparative Examples Example 1 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.

Ingredients listed below A1 listed in Table 1 74 parts by weight 8 listed in Table 2
1 12 parts by weight 01 listed in Table 3
After mixing 14 parts by weight of 1 part by weight of carbon black using a Henschel mixer, the mixture was granulated using a twin-screw extrusion fi (IJPcM30 manufactured by Ikegai Iron Works Co., Ltd.) at a resin temperature of 220°C to obtain a granular resin composition.

The melt flow rate of the obtained resin composition was determined by ASTM
Measured according to D 1238L.

K (Kuri-1 A component listed in Table 1, Table 2 and Table m3, Btu
A granular resin composition was obtained in the same manner as in Example 1 except that Component C was used in the formulation shown in Table 4.

The melt flow rate of the obtained resin composition was determined by ASTM
Determined according to D 1238L.

The same procedure as in Example 1 was used except that the A component, B component, and Crlt component listed in Tables 1, 2, and 3 were used according to the prescription listed in Table 5. A granular resin composition was obtained.

The melt flow rate of the obtained resin composition was determined by ASTM
Determined according to D 1238L.

The melt flow rates determined in the above Examples and Comparative Examples are listed in Table m4 and Table 5, respectively. Examples 1 to 5 and Comparative Example 1 A test piece was prepared by molding the granular resin composition obtained in steps 4 to 4 using an injection molding machine (L5220E manufactured by Next Summer Machinery Co., Ltd.) at a clamping force of 200 tons and a resin temperature of 200°C.

The initial bending modulus, tensile strength, isot impact strength and falling weight impact strength (FD) of this test piece were measured according to the following methods.

Initial bending modulus: ASTM D? 90 (kg)
/c2) Tensile strength: ASTM D 638 (kg/c
m2) Izot impact strength: ASTM D 256 (
kg0CII/ClII) Falling weight impact strength knee 120X (kg・
Darts weighing 3 kg and having a tip diameter of % inch were dropped against a 130 x 3 square plate at different heights, and the energy value at which 50% of the samples were destroyed was determined.

The measurement results are shown in Tables 6 and 7.

The resin compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were molded with a mold clamping force of 25 using a bumper molding machine (manufactured by Kobe M).
00), resin temperature 200℃, injection pressure 800kg/
The bumper shown in FIG. 1 was obtained by molding under the following conditions: am'' (primary), 500 kg/es2 (secondary), and an injection speed of 241/sec.

The bumper is 1500mm wide and deep! 300mm.

Height 300-1, front thickness 3.5 wheels, @ part thickness 3
, 5 mm.

The obtained bumper was examined for the presence or absence of 70-marks and the presence or absence of voids. The results are shown in Tables 8 and 9.

Here, the 70-mark refers to a pattern such as a waveform appearing on the surface of a molded product (bumper), and the void refers to a space created inside the bumper (a spatial head where no resin composition exists).

On the surface of the bumper where voids have occurred, there are usually four approximately circular or oval parts called "sink marks". "Sink"
This area is usually clearly visible even after the bumper is painted.

A cross-section of the bumper with voids and sink marks is shown in FIG.

[Effects of the Invention 1 According to the present invention, the present invention has excellent impact resistance, rigidity, and coating properties;
A resin composition suitable for manufacturing automobile bumpers that can be easily molded without generating voids or 70-marks is obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the bumper. FIG. 2 is a cross-sectional view of a bumper with voids and sink marks. 1... Void 2... Sink mark 3... Date patent applicant: 1 person other than Nissan Automobile Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1. (A) 60 to 85 parts by weight of a crystalline propylene-ethylene block copolymer (component A) having an ethylene unit content of 10 to 30 mol% and a melt flow rate of 10 to 30 g/10 min. , where the above component A is (A-I) 50 to 80% by weight of a propylene polymer component (A-I component) having an isotactic index of 90 or more.
(A-II) A propylene-ethylene copolymer component (A-II component) having an ethylene unit content of 40 to 60 mol% and an intrinsic viscosity of 2.0 to 4.0 dl/g (A-II component) exceeding 16% by weight and 20% by weight and (A-III) an ethylene copolymer component (A-III component) having a propylene unit content of 10 mol% or less and an intrinsic viscosity of 1.0 to 10.0 dl/g (A-III component) 3 to 20% by weight, The above A-I component, A-II component and A-II
The weight percent of component I is based on the total weight of these three components. Amorphous ethylene α with a degree of oxidation of 15% or less
- 5 to 20 parts by weight of an olefin random copolymer component (component B), and (C) 8 to 15 parts by weight of a talc or calcium carbonate component (component C) with an average particle size of 0.1 to 5μ, A resin composition for an automobile bumper having a melt flow rate of 10 g/10 minutes or more, wherein the parts by weight of component A, component B, and component C are selected such that the total weight part is 100 parts by weight.