JPH11207772A - Manufacture of automobile injection molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sufficiently the mechanical physical value without using a large extruder while avoiding the complication of the manufacturing process. SOLUTION: A pellet-shaped mix kneaded resin formed by mix kneading a first ethylene-propylene polymer of 50-100 g/10 minutes melt flow rate (230 deg.C, load: 2.16 kgf.) and 80-99 wt.% propylene content with a second ethylene- propylene polymer of 1-20 g/10 minutes melt flow rate and 30-60 wt.% propylene content and a master batch formed by mixing a mix kneaded resin and a 2-6 μm average diameter filler at the ratio of 100:50-80 wt.% are provided. The resins of two kinds thus formed are introduced into a hopper 6 of an injection molding machine 5 and injection molded while being heat melted. The blend ratio of the first polymer with the second polymer is set at 60-90:10-40 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to injection molded articles for automobiles such as door trims and pillar trims, and more particularly, ethylene-propylene polymer containing filler (PP) as a molding resin.
The present invention relates to an improvement in a resin composition of an injection molded article for an automobile using the same.

[0002]

2. Description of the Related Art Conventionally, polypropylene is often used in injection molded articles for automobiles such as door trims and pillar trims. Polypropylene is superior in heat resistance and stress cracking resistance to high-density polyethylene, which is widely used, but has low low-temperature impact resistance. For this reason, conventionally, door trim and pillar trim are manufactured using an ethylene-propylene polymer obtained by polymerizing polyethylene on polypropylene.

FIGS. 2 and 3 show such a manufacturing method. In the prior art shown in FIG. 2, first, an ethylene-propylene polymer (hereinafter, referred to as an EPP polymer) in the form of pellets is charged into an inlet hopper 11 of a twin-screw extruder 10, heated and melted, and then discharged from a hopper 12 at an outlet. Filler-like talc (fine-grained talc) is added and dispersed to produce talc-containing EPP polymer pellets, which are charged into a hopper 6 of an injection molding machine 5, heated and melted, and injection-molded into a mold 7. Thus, a predetermined molded product is manufactured.

[0004]

However, in the resin member manufactured by the conventional method, although the mechanical property value and the impact value are not less than a certain value, the mixing of the filler talc and the EPP polymer is biaxial. A large extruder such as a screw must be used, and the man-hours for kneading are high and the cost is high. Therefore, as shown in FIG. 3, an EPP polymer having a very high fluidity including a filler (a master batch containing a filler) is pelletized, and the mechanical properties of the pelletized master batch and the interior material are determined. Conventionally, a PP resin to be discharged is put into a hopper 6 of an injection molding machine 5, heated and melted while mixing the two in the injection molding machine 5 and injection molded into a mold 7 to produce a predetermined molded product. Using technology.

However, according to the prior art, a resin molded product can be produced at low cost by using only the injection molding machine 5 without using a large-sized extruder. , The dispersion of the filler is poor and the mechanical properties are low. In view of the drawbacks of the prior art, the present invention has sufficient mechanical properties without using a large-sized extruder and while avoiding complicated production steps.
In particular, it is an object of the present invention to provide a method of manufacturing an injection molded product for an automobile such as a door trim and a pillar trim having an improved low-temperature impact value.

[0006]

In order to solve the above-mentioned problems, the present invention has a melt flow rate of 50 to 100 g / m.
A first ethylene-propylene polymer having a propylene content of 10 to 20 minutes (230 ° C., load: 2.16 Kgf) and a propylene content of 80 to 99% by weight, and a melt flow rate of 1 to 20 g /
10 minutes and the second having a propylene content of 30 to 60% by weight.
A kneaded resin body formed by kneading an ethylene-propylene polymer with an extruder and a filler having an average particle size of 2 to 6 μm are kneaded at a ratio of 100: 50 to 80% by weight. An injection-molded article for automobiles, comprising preparing a pelletized master batch, charging these two types of resin bodies into a hopper 6 of an injection molding machine 5 and performing injection molding while heating and melting. We propose a manufacturing method.
The mixing ratio of the first polymer and the second polymer is 60 to
It is good to set to 90:10 to 40% by weight. In general, talc is preferably used for the filler, and its particle size is preferably set to an average particle size of 2 to 6 μm. Bare particle size 2μm
Below, the dispersion of the filler is not sufficient, and when it is 6 μm or more, the mechanical properties are reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only. The present invention will be described in comparison with the prior art. First, the melt flow rate was 30 g / 10 min (23
A third ethylene-propylene polymer having a temperature of 0 ° C., a load of 2.16 Kgf) and a propylene content of 90% by weight;
Second pellet-shaped kneading formed by kneading a third ethylene-propylene polymer having a melt flow rate of 10 g / 10 min and a propylene content of 25% by weight with a single-screw extruder 1 as shown in FIG. Conventionally, a resin body (hereinafter referred to as PP) is put into a hopper 6 of an injection molding machine 5, heated and melted while mixing the two in the injection molding machine 5, and injection molded into a mold 7 to produce a door trim. Technology 2.

Next, a master batch prepared by kneading the second kneaded resin body PP and a filler having an average particle diameter of 2 to 3 μm at a ratio of 100: 75% by weight and preparing a pellet is prepared. As shown in FIG. 3, a door trim is manufactured by putting the resin body into a hopper 6 of an injection molding machine 5 and performing injection molding while heating and melting the resin body.

On the other hand, in the present invention, the melt flow rate is 50 to 100 g / 10 minutes (230 ° C., load: 2.1
6 kgf) and the propylene content is 80 to 99% by weight.
A first ethylene-propylene polymer (hereinafter referred to as PPa) and a second ethylene-propylene polymer (hereinafter referred to as PPb) having a melt flow rate of 1 to 20 g / 10 min and a propylene content of 30 to 60% by weight. As shown in FIG. 1, a first kneaded resin body formed by kneading with a single-screw extruder 1, a first kneaded resin body and an average particle diameter of 2
A master batch prepared by kneading a filler having a size of about 3 μm at a ratio of 100: 75% by weight and preparing a pellet is prepared, and these two types of resin bodies are put into a hopper 6 of an injection molding machine 5 and heated and melted. In this example, a door trim was manufactured by injection molding while performing injection molding. In Example 1, PPa and PPb were used.
Is 80:20, and in Example 2, PPa and PP
b: 90:10, and for Example 3, PPa and P
The ratio of Pb was set to 60:40, respectively.

As a comparative example, the ratio of PPa to PPb is 80:
The first kneaded resin body set to 20 and the second kneaded resin body (PP) used in the prior art were mixed with an average particle size of 2
A master batch prepared by kneading a filler having a size of about 3 μm at a ratio of 100: 75% by weight and preparing a pellet is prepared, and these two types of resin bodies are put into a hopper 6 of an injection molding machine 5 and heated and melted. While the door trim was manufactured by injection molding, the product was used.

The prior arts 1 and 2 and the first to third embodiments.
Specific gravity and Izod impact value (KJ
/ M ² ), heat distortion temperature H.I. D. T (° C.) and flexural modulus (MPa) were examined. FIG. 4 shows the results.

First, for the prior art 2 having no filler, the Izod impact value (KJ / m ² ), the heat distortion temperature D. Although both T (° C.) and flexural modulus (MPa) show preferable numerical values, the molded product has no gloss and no favorable appearance quality was obtained because no filler was contained.

[0013] In addition, the prior art 1 provided good appearance quality due to the inclusion of the filler, but the Izod impact value was 17 (KJ / m ² ), which was the same as that of the prior art 2 (17).
(KJ / m ² )). This is the same in Comparative Example 1 in which a masterbatch is formed by using the second kneaded resin body (PP) used in the conventional technique,
The Izod impact value is also 20 (KJ / m ² ), and the thermal deformation temperature is also 126 (° C.), which is lower as in the prior art 1.

On the other hand, in Examples 1 to 3, the Izod impact value was 23 to 27 (KJ / m ² ) and the heat deformation temperature was 12
8-134 (° C), flexural modulus 1800-1910
(MPa) and the same physical property values as in the prior art 2 in which no filler was added. The mixing ratio of the first polymer and the second polymer is 60 to 90:10 to 4
It is good to set to 0% by weight. In general, talc is preferably used for the filler, and its particle size is preferably set to an average particle size of 2 to 6 μm. When the particle size is less than 2 μm, the filler is not sufficiently dispersed, and when the particle size is more than 6 μm, the mechanical properties decrease.

Next, in the first embodiment, master batches in which the particle diameter of the filler to be kneaded with the first kneaded resin body was changed between 2 and 10 were prepared, and the first kneaded resin body and the master batch were prepared. Each of these master batches is molded into a resin body by an injection molding machine 5.
The Izod impact value was measured for a door trim manufactured by injection molding while being heated and melted in the hopper 6, and the results are summarized in a graph with the filler particle diameter as the horizontal axis as shown in FIG. I tried. Further, as is apparent from this figure, it was understood that the mechanical properties decreased when the particle diameter was 6 μm or more, and that the filler was not sufficiently dispersed when the particle diameter was 2 μm or less.

[0016]

As described above, according to the present invention, door trims and pillar trims having sufficient mechanical properties, particularly low-temperature impact values, without using a large-sized extruder and avoiding complicated production steps. And the like can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an extrusion / injection manufacturing process to which the present invention is applied.

FIG. 2 is a schematic view showing an extrusion / injection manufacturing process to which a first prior art is applied.

FIG. 3 is a schematic view showing an extrusion / injection manufacturing process to which a second prior art is applied.

FIG. 4 shows specific gravity, Izod impact value (KJ / m ² ) for the prior arts 1 and 2, Examples 1 to 3 and Comparative Example, respectively.
Heat deformation temperature H. D. It is a table | surface figure which shows the result of having investigated T (degreeC) and bending elastic modulus (MPa), respectively.

FIG. 5 is a graph showing a relationship between an Izod impact value and a filler particle size.

[Explanation of symbols]

 1,10 Extrusion molding machine 5 Injection molding machine

Claims (2)

[Claims] 1. A melt flow rate of 50 to 100 g /
A first ethylene-propylene polymer having a propylene content of 10 to 20 minutes (230 ° C., load: 2.16 Kgf) and a propylene content of 80 to 99% by weight, and a melt flow rate of 1 to 20 g /
10 minutes and the second having a propylene content of 30 to 60% by weight.
A kneaded resin body formed by kneading an ethylene-propylene polymer with an extruder and a filler having an average particle size of 2 to 6 μm are kneaded at a ratio of 100: 50 to 80% by weight. A pelletized master batch is prepared, and these two types of resin bodies are put into a hopper of an injection molding machine, and injection molding is performed while heating and melting. Method. 2. The production of an injection molded article for an automobile according to claim 1, wherein the compounding ratio of the first polymer and the second polymer is set in a range of 60 to 90:10 to 40% by weight. Method.