JPH02199146A - Polypropylene resin composition for injection molding - Google Patents

Abstract

PURPOSE:To obtain the title composition to which a melt index(MI) suitable for injection molding can be imparted without lowering its normal-temperature impact resistance by adding an amorphous polyolefin to a base composition formed by adding talc to a polymer blend of a crystalline polypropylene with an ethylene/propylene rubber. CONSTITUTION:100 pts.wt. polymer component (a blend formed by blending polypropylene with an ethylene/propylene rubber in a weight ratio of 9/1-5/5) is mixed with 2-15 pts.wt. inorganic filler (entirely or mainly consists of talc of a mean particle diameter of 0.4-4mum) and 2-15 pts.wt., desirably 5-10 pts.wt. amorphous poly(alpha-olefin) (of a melt viscosity of 1000-10000cp, desirably 1000-3000cp) to obtain a polypropylene resin composition for injection molding desirable for large and long products requiring high impact resistance, especially automobile bumpers, moldings and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a polypropylene resin composition for injection molding. In particular, it is suitable as an injection molding material for large or long products such as automobile pambas and malls, and products that require impact resistance.

In addition, in the following explanation, rP PJ is polypropylene,
rEPRJ is an ethylene propylene rubber-based polymer, r
MIJ is the respective abbreviation for Melt Index.

Moreover, the compounding unit is a weight unit unless otherwise specified. The value of Ml is based on JIS K 7210 (Method A, conditions: test temperature 230°C, test load 2.16kgf), and the unit g/10 minutes is omitted.The value of impact resistance is based on JIS Izot gI specified in 7110! It is based on the test method.

<Prior art> Automotive molded products such as the above-mentioned Bamba use a polymer component whose main component is a polymer blend of crystalline PP mixed with EPR for the purpose of reducing weight and improving impact resistance. For the purpose of improving rigidity, it was manufactured by injection molding using a pp resin composition for injection molding having a basic composition containing an appropriate amount of an inorganic filler such as talc.

<Problems to be Solved by the Invention> However, during the above injection molding, the required strength of the product, especially impact resistance at room temperature (for example, impact resistance at room temperature of 50
kgf-cm/rats or more),
As crystalline PP, it is necessary to use one with a low melt index (Ml value (for example, one with an Ml value of less than 20), that is, one with a high molecular weight.
The MI of the PP resin composition (molding material) containing an inorganic filler and an inorganic filler was also smaller than a value suitable for injection molding (usually 10 to 20), causing problems in moldability.

In other words, with normal injection pressure (300 kg/cm"), short shots (filling defects) occur due to poor material flow, and if the injection pressure is set too high to avoid short shots, a large amount of paris will be generated. This tendency, which is likely to occur, is particularly noticeable in the case of large-sized molded products in which the distance from the injection gate to the final part of the material flow is long.

In view of the above, an object of the present invention is to provide a PP resin composition for injection molding which has an Ml suitable for injection molding without causing a large decrease in various physical properties, especially a large decrease in room temperature impact resistance. do.

Means for Solving the Problems> In order to solve the above problems, the present inventors have made extensive efforts in development and have come up with a PP resin composition for injection molding having the following structure.

An average particle size of 0.5 for 100 parts of a polymer component whose entire or main component is a polymer blend consisting of crystalline PP and EPR in a blending ratio of the former/latter = 971 to 515.
It has a basic composition in which 5 to 20 parts of an inorganic filler whose entire or main component is talc of ~4 μm is blended, and 2 to 20 parts of amorphous poly-α-olefin is added to 100 parts of the polymer component.
A PP resin composition for injection molding containing 15 parts.

<Detailed explanation of means> The PP resin composition for injection molding of the present invention has a basic composition consisting of the following polymer component (1) and the inorganic filler (2), and the following amorphous (3). This product contains poly-α-olefin.

(1) Polymer component: Crystalline pp and EPR are former/latter = 9/1 to 515 (
Preferably, the total or main component is a polymer blend having a blending ratio of 8/2 to 6/4.

If the amount of EPR is less than the above, it will not be possible to improve the low-temperature impact resistance of the product, and if it is in excess, the product will have a practical strength (for example, tensile strength of 140 kgf).
101' or more) is difficult to obtain and is therefore undesirable.

Here, the crystalline PP includes a propylene homopolymer and a propylene-ethylene copolymer, but preferably a propylene-ethylene copolymer with an ethylene content of 5 to 10%,
Desirable from the standpoint of obtaining low temperature resistance** and practical strength.
Further, it is desirable that the Ml of the crystalline PP is in the range of 10 to 30. If it is less than 10, problems tend to occur in moldability, and if it exceeds 30, problems tend to occur in room temperature impact resistance.

EPR may be either an ethylene propylene polymer or an ethylene propylene terpolymer, where E
The Mooney viscosity range of PR is 1O~30ML, and
(100°C) is desirable.

If it is less than 10, low-temperature impact resistance is likely to be adversely affected;
If it exceeds this amount, the compatibility with crystalline PP decreases, and molding defects are likely to occur.

In addition, this polymer component includes high-density polyethylene,
From the viewpoint of improving impact strength, etc., it can be blended in an appropriate amount (usually 1 to 10 wt% in the polymer component).

(2) Inorganic filler: All or the main component is talc with an average particle size of 0.5 to 4 μm (preferably 1 to 3 μm). If the main component is an inorganic filler other than talc, the rigidity will decrease.

Examples of inorganic fillers that can be added as subcomponents include calcium carbonate and mica. Also, the particle size is 0
．． If it is less than 5 μm, poor dispersion is likely to occur due to agglomeration phenomenon, and if it exceeds 4 μm, surface smoothness deteriorates, resulting in poor molding.

The amount of talc to be blended is 5 to 20 parts per 100 parts of the polymer component. If it is less than 5 parts, it will be difficult to obtain practical strength in the molded product, and if it exceeds 20 parts, impact resistance will be adversely affected.

(3) Amorphous poly-α-olefin: Here, amorphous poly-α-olefin refers to amorphous PP, amorphous propylene-ethylene copolymer, amorphous propylene-ethylene copolymer,
1-butene copolymer and the like can be mentioned. The range of melt viscosity of this amorphous polyα-olefin is 1000 to 10
000cP (preferably 1000~3000c
P ) is desirable.If it is less than 1000 cP, impact resistance is likely to be adversely affected and it becomes difficult to obtain practical strength, and if it exceeds 10000 cP, it is difficult to obtain the Ml adjustment effect.

In addition, this amorphous poly-α-olefin functions as an Ml adjuster, and its blending amount is determined to meet the target Ml
(2 to 15 parts per 100 parts of polymer component depending on fl)
parts (preferably 5 to 10 parts), less than 2 parts,
The effect of preparing Ml cannot be obtained, and if it exceeds 15 parts, impact resistance tends to be adversely affected and it becomes difficult to obtain practical strength.

The PP resin composition having the above-mentioned constituent requirements is prepared by adding auxiliary materials such as stabilizers (thermal stabilizers, ultraviolet absorbers, light stabilizers, etc.) and mold release agents as necessary, and then using a mixer/kneader.・Mix, knead, and granulate each in a granulator to make an injection molding material (see Figure 1).

Then, using the molding material, products such as the above-mentioned bangers and side moldings are injection molded.

<Actions and effects of the invention> The PP resin composition for injection molding of the present invention comprises crystalline PP and E
talc with an average particle size of 0.5 to 4 μm is added to 100 parts of a polymer component consisting entirely or mainly of a polymer blend with a blending ratio of former/latter = 9/1 to 515. By having a basic composition in which 5 to 20 parts of an inorganic filler as a component are blended, and 2 to 15 parts of amorphous poly-α-olefin are blended with respect to 100 parts of the polymer component, as described below. As shown in Examples, the molded product has a Ml that can be passed through injection molding without causing a large decrease in various physical properties, particularly in room temperature impact resistance.

Therefore, as in the past, due to inappropriate Ml value,
During injection molding, short shots (filling defects) or large amounts of flakes should be avoided.
will almost disappear.

<Examples> Examples carried out to confirm the effects of the present invention will be described below along with comparative examples.

A molding material is prepared by mixing, kneading, and granulating the materials according to the formulations of each Example and Comparative Example shown in Table 1 using the general-purpose method shown in FIG.

The Ml of the thus obtained molding material was measured, and the molding material was molded into the product cavity of a Banba mold (mold temperature: 23°C) using an injection molding machine at an injection pressure of 300 kg/cm' and a nozzle temperature of 220°C. was injected and molded.

The various physical properties indicated were then measured for each of the obtained molded articles. Tensile elongation and tensile strength are respectively JIS
K 7113 (test piece = No. 1 type, tensile speed: 50I/
■In). Moreover, the moldability was determined visually as to the presence or absence of short shots or sink marks, and the results were expressed as "absent - 0", "present" as "×".

The measurement results are shown in Table 1. Even when the Ml value is suitable for molding, the physical properties of each example do not deteriorate significantly, especially the impact resistance at room temperature hardly decreases (Examples 1 and 2).
(Comparison with Comparative Example 1), whereas Comparative Examples 2 and 3 using crystalline PP with a high Ml value both showed a significant decrease in room temperature impact resistance. It can be seen that in the case of PP (Comparative Example 3), it is difficult to adjust the Ml of the composition, that is, to improve the moldability.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing a general-purpose manufacturing method for a molding material having the composition of the present invention. Patent application Toyoda Gosei Co., Ltd. Uat Polyb EIJ815HK Mitsubishi Noblen QC-2C uBIJ Rib 0J830HV Showlex 56002H JSREP911P Talc LMR100 ＾PAO83＾15 Ube Industries Mitsubishi Oil Chemical Ube Industries Showa Denko Japan Synthetic Rubber Fuji Talc Ube Kosan pyrene-ethylene Polymer 89&〃
-〃 A-electroethylene 1-discharge polymer polymer Viscosity: 15ML4 average diameter
1.8μ■ - Melt viscosity 15OOcP Voluntary Written amendment of amendment procedure 1, Indication of the case 1999 Patent Application No. 018835 2, Name of the invention Polypropylene resin composition for injection molding 3, Person making the amendment Relationship with the case Patent Applicant address: Toyoda Gosei Co., Ltd. 4, agent address: Sakae 2-chome, Naka-ku, Nagoya, Aichi Prefecture 460 it#k
TG phone number Nagoya (052) 221-7856
(Yogi>-Detailed explanation column 6, contents of amendment (1) Page 11 of the specification is amended as shown in the attached sheet.

Claims (1)

[Scope of Claims] Polymer component 100 whose entire or main component is a polymer blend consisting of crystalline polypropylene and ethylene propylene rubber-based polymer in a blending ratio of the former/latter (weight ratio) = 9/1 to 5/5. Based on parts by weight, the average particle size is 0.
It has a basic composition in which 5 to 20 parts by weight of an inorganic filler whose entire or main component is talc of 5 to 4 μm is blended, and 2 to 15 parts by weight of amorphous polyα-olefin per 100 parts by weight of the polymer component. A polypropylene resin composition for injection molding, comprising: parts by weight.