JPH06299010A - Polyethylene polymer alloy - Google Patents

Abstract

PURPOSE:To improve the impact resistance and surface hardness by incorporating specified polymers for improving vibration damping into a crystalline polyethylene. CONSTITUTION:100 pts.wt. crystalline polyethylene having a degree of crystallization of at least 40% and an MI (190 deg.C) of 1-50g/10min is mixed with polymers for improving vibration damping comprising 5-200 pts.wt. crystalline polybutylene having an MI (190 deg.C) of 0.1-10g/10min and 1-100 pts.wt. crystalline polypropylene having an MFR (230 deg.C) of 10-70g/10min.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyethylene-based polymer alloy (PE-based polymer alloy). In particular, the present invention is suitable for vibration-damping resin molded products that require impact resistance and surface hardness.

Examples of the vibration-damping resin molded article include engine exterior covers such as engine undercovers, fender liners, and dust covers around the engine of automobiles, as well as home appliance cabinets and building material parts.

The following is a list of abbreviations used in this specification, and the meanings of the terms are defined.

PE ... Polyethylene PP ... Polypropylene MI (melt index) ... When the force of 211.82 N is applied at 190 ° C., g of the amount of resin extruded from the orifice of diameter 2.1 mm φ × 8 mm L (see JIS K 7210) .

MFR (melt flow rate) ... 230 ° C.
MI in.

[0006]

2. Description of the Related Art The vibration-damping resin molded product used for the undercarriage of automobiles as described above is
Since it is hit by flying stones, impact resistance and surface hardness are required in addition to vibration damping performance.

Since crystalline PE is inexpensive and has a relatively low density, it is widely used as a material for hard plastic moldings for automobiles.

[0008] When crystalline polybutylene is blended with crystalline PE, the loss factor of the molded product is improved.

However, the compounding of the polybutylene decreases the impact resistance and surface hardness of the molded product.

In view of the above, it is an object of the present invention to provide a PE-based polymer alloy capable of improving impact resistance and hardness, without lowering the vibration damping property.

[0011]

Means for Solving the Problems The inventors of the present invention have earnestly made efforts to solve the above problems, and as a result, have conceived a PE polymer alloy having the following constitution.

A PE polymer alloy in which crystalline polybutylene is blended with crystalline PE as a vibration damping improving polymer is characterized in that crystalline PP is added and mixed as an impact strength improving polymer.

[0013]

[Detailed Description of Means] Next, a detailed description will be given of each configuration of the above means. In the following description, composition ratios and blending units are weight units unless otherwise specified.

(1) The crystalline PE means a crystallinity of 40%
The above is the high density PE (density 0.941 to 0.965,
HD), medium density PE (0.926 to 0.940, MD), low density PE (0.910 to 0.925, LD), linear low density PE (0.9
10-0.925, LLD) and mixtures thereof can be used. Usually, it is desirable to use high-density PE as a base from the viewpoint of shape retention (strength).

This crystalline PE usually has MI = 1 to 5
0 g / 10 minutes (190 ° C) (desirably 2 to 30 g / 1
Use 0 minute). If the MI is less than 1 g / 10 minutes, the moldability and the appearance of the molded product are likely to deteriorate.
If it exceeds 0 g / 10 minutes, the impact resistance tends to be adversely affected.

(2) The crystalline polybutylene has a crystallinity of 30% or more, and a butene-1 homopolymer, an ethylene / butene-1 copolymer, and a mixture thereof can be used. . An ethylene / butene-1 copolymer having an ethylene content of 0.5 to 20% (desirably 1 to 10%) is used in order to improve the compatibility with the crystalline PE and the crystalline PP. It is desirable to do.

Further, the crystalline polybutylene is usually MI
= 0.1 to 10 g / 10 minutes (190 ° C) (preferably 0.2 to 5 g / 10 minutes). If the MI is less than 0.1 g / 10 minutes, the moldability and the appearance of the molded product are likely to deteriorate, and if it exceeds 10 g / 10 minutes, the impact resistance is likely to be adversely affected.

The mixing ratio of the crystalline polybutylene in the polymer alloy is usually 5 to 200 parts, preferably 1 part.
0 to 150 parts. If it is less than 5 parts, the effect of improving the vibration damping property of the molded product is difficult to be exerted, and if it exceeds 200 parts, the molded product has sufficient impact resistance and the necessity of blending PP described below is eliminated.

(3) The crystalline PP has a crystallinity of 3
It means 0% or more, and a propylene homopolymer, an ethylene / propylene block copolymer, an ethylene / propylene random copolymer, and a mixture thereof can be used. In order to improve the miscibility (compatibility) with crystalline PE and crystalline PP, the ethylene content is from 1 to 1.
20% (preferably 2-10%) ethylene butene-
It is desirable to use one copolymer.

The crystalline PP usually has MFR = 10.
~ 70 g / 10 minutes (230 ° C) (preferably 30 to 60)
g / 10 minutes). The above MFR is 10g /
If it is less than 10 minutes, the molding processability and the appearance of the molded product are apt to deteriorate, and if it exceeds 70 g / 10 minutes, the impact resistance is liable to be adversely affected.

The mixing ratio of the crystalline PP in the polymer alloy is usually 1 to 100 parts, preferably 2 to 80 parts. If it is less than 5 parts, the effect of improving the impact resistance of the molded product is difficult to be exerted, and if it exceeds 100 parts, the physical properties of PE itself are impaired and molding at low temperature (170 ° C.) becomes difficult.

(3) From the viewpoint of further improving the impact resistance, this polymer alloy contains an amorphous (crystalline degree of 10% or less) ethylene-α olefin copolymer in an appropriate amount, usually crystalline PE100. It is desirable to mix 0 to 10 parts with respect to parts. Examples of the α-olefin include propylene, butene-1, pentene-1, hexene-1 and the like.

(4) The polymer alloy can be prepared by using a conventional kneader such as a single-screw extruder, a twin-screw extruder, a kneader, a Brabender or a Banbury mixer. Usually, each polymer component is mixed in a predetermined ratio by a tumbler blender, a Henshur mixer, a ribbon mixer, etc., and then kneaded by an extruder or the like to obtain a pellet-shaped molding material. Using the material, vibration damping resin moldings such as engine undercovers, fender liners, and dust covers are manufactured by injection molding or the like.

It should be noted that the polymer alloy includes an antioxidant, an ultraviolet absorber, a lubricant, an antistatic agent, a nucleating agent, a pigment, a flame retardant,
You may mix additives, such as a filler and a processing aid.

[0025]

As described above, the PE-based polymer alloy of the present invention is a PE-based polymer alloy in which crystalline polybutylene is blended as a vibration-damping-improving polymer in crystalline PE, and is crystallized as an impact-strength-improving polymer. Sex PP
By adding and mixing, as shown in the examples below, compared with PE-based polymer alloy containing only crystalline polybutylene, the vibration damping performance is improved (rather improved) and the impact resistance is improved. In addition, hardness can usually be increased.

Therefore, the PE polymer alloy of the present invention is suitable as a molding material for vibration damping resin molded articles such as automobile engine undercovers, fender liners, dust covers and the like which are hit by flying stones and the like.

[0027]

EXAMPLES Examples and comparative examples according to the present invention will be described below.

A. Preparation of test pieces The mixture of each compounding recipe shown in Tables 1 and 2 was used with a twin-screw extruder (L / D of each screw = 27, φ = 30 mm).
Melt kneading was performed to prepare a pellet molding material.

The specifications of the polymers used in the examples and comparative examples are as follows.

(1) Crystalline PE: High density PE ... MI = 9 g / 10 minutes Medium density PE ... MI = 20 g / 10 minutes Linear low density PE ... MI = 15 g / 10 minutes (2) Polybutylene: Polybutene (A ) ... MI = 1.0 g / 10 minutes, ethylene-butene-1 copolymer having an ethylene content of 2.9%.

Polybutene (B) ... MI = 0.2 g / 1
Ethylene / butene-1 copolymer having an ethylene content of 9.1% for 0 minutes.

(3) PP: PP (A) ... MFR = 45 g / 10 minutes, ethylene / propylene copolymer having an ethylene content of 7.1%.

PP (B) ... MFR = 50 g / 10 minutes,
Ethylene / propylene copolymer having an ethylene content of 4.3%.

PP (C) ... MFR = 40 g / 10 minutes,
Ethylene homopolymer having an ethylene content of 0%.

A test piece was molded using an injection molding machine using the above pellet material. The injection conditions were a cylinder temperature of 220 ° C and a mold temperature of 40 ° C.

B. Test method For each test piece, the tests of the following items were performed.

(1) Izod Impact Value at Room Temperature According to ASTM D256, a test piece with a molded notch was tested at an ambient temperature of 23 ° C.

(2) Low Temperature Izod Impact Value A test piece with a molded notch was tested according to ASTM D256 at an ambient temperature of -30 ° C.

(3) Rockwell hardness It was performed according to JIS K7202.

(4) Flexural Modulus A test was conducted according to ASTM D790.

(5) Loss coefficient A square flat plate having a length of 150 mm and a width of 150 mm and a thickness of 3 mm was prepared by injection molding.
The transfer function was measured by vibrating at 1G. Then, the loss coefficient η was calculated from the primary resonance point by the half-width method.

C. Test Results and Evaluation From the test results shown in Tables 1 and 2, the polymer alloy was obtained by adding crystalline PP, crystalline polybutylene, and crystalline PP.
In addition to the fact that each of the examples of the three-component system in which is added, the impact resistance is significantly improved as compared with the respective comparative examples of the two-component system containing only crystalline PE and crystalline polybutylene, It can be seen that the hardness does not decrease, but rather improves, and the hardness generally increases.

Further, when a copolymer with ethylene is used as the crystalline PP (Example 6), the impact resistance is superior to that when a homopolymer is used (Example 7). I understand.

As a reference example, Table 2 shows the physical property data of each PE alone.

[0045]

[Table 1]

[0046]

[Table 2]

Claims (1)

[Claims] 1. A polyethylene-based polymer alloy in which crystalline polybutylene is blended with crystalline polyethylene as a vibration damping property improving polymer, wherein crystalline polypropylene is added and mixed as an impact strength improving polymer. Polymer alloy.