JP3028700B2 - Polyethylene polymer alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene polymer alloy (PE polymer alloy). In particular, the present invention is suitable for a vibration-damping resin molded product requiring impact resistance and surface hardness.

[0002] Examples of the vibration damping resin molded product include automotive exterior components such as an engine under cover, a fender liner, and a dust cover around an automobile engine, as well as household electric appliance cabinets and building material parts.

[0003] 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): the number of g of resin flow extruded from an orifice having a diameter of 2.1 mm φ × 8 mm L when subjected to a force of 211.82 N at 190 ° C. (see JIS K7210).

MFR (melt flow rate): 230 ° C.
MI.

[0006]

2. Description of the Related Art Vibration damping resin molded products used for undercars of automobiles as described above are:
Since a stepping stone or the like is hit, impact resistance and surface hardness are required in addition to vibration damping performance.

[0007] Since crystalline PE is inexpensive and has a relatively low density, it is widely used as a material for molded articles of hard plastics for automobiles.

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

However, the blending of the above polybutylene lowers the impact resistance and surface hardness of the molded article.

[0010] In view of the above, an object of the present invention is to provide a PE polymer alloy capable of improving impact resistance and further improving hardness without a reduction in vibration damping properties.

[0011]

Means for Solving the Problems The inventors of the present invention have made intensive efforts for development in order to solve the above-mentioned problems, and as a result, have found a PE-based polymer alloy having the following structure.

[0012] A vibration damping resin composition containing 5-200 parts by weight of crystalline polybutylene per 100 parts by weight of crystalline PE
In the polyethylene-based polymer alloy for molded products, the
Crystalline polybutylene having an ethylene content of 0.5 to 20%;
Tylene / butene-1 copolymer, and crystalline polypropylene is based on 100 parts by weight of crystalline polyethylene.
It is characterized in that 1 to 100 parts by weight are added and mixed.

[0013]

[Detailed Description of Means] Next, each component of the above means will be described in detail. In the following description, composition ratios and blending units are weight units unless otherwise specified.

(1) The above-mentioned crystalline PE refers to a crystallinity of 40%.
Higher density PE (density 0.941 ~ 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. Usually, it is desirable to use high-density PE as a base from the viewpoint of shape retention (strength) and the like.

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

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

Also, crystalline polybutylene is usually MI
= 0.1 to 10 g / 10 min (190 ° C) (preferably 0.2 to 5 g / 10 min) is used. When the MI is less than 0.1 g / 10 min, the moldability and the appearance of the molded article are liable to deteriorate, and when it exceeds 10 g / 10 min, the impact resistance is likely to be adversely affected.

The proportion of the crystalline polybutylene in the polymer alloy is usually 5 to 200 parts, preferably 1 to 200 parts.
0 to 150 parts. If the amount is less than 5 parts, the effect of improving the vibration damping properties of the molded article is hardly exhibited. If the amount exceeds 200 parts, the molded article has sufficient impact resistance, and the necessity of blending PP described later is eliminated.

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

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

Here, the compounding ratio of the crystalline PP in the polymer alloy is usually 1 to 100 parts, preferably 2 to 80 parts.
Department. If it is less than 1 part, it is difficult to improve the impact resistance of the molded article. 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 (a crystallinity of 10% or less) ethylene-α-olefin copolymer in an appropriate amount, usually crystalline PE100. It is desirable to mix 0 to 10 parts per part. Here, examples of the α-olefin include propylene, butene-1, pentene-1, and hexene-1.

(4) The above-mentioned polymer alloy can be prepared using a conventional kneader such as a single screw extruder, a twin screw extruder, a kneader, a Brabender, a Banbury mixer and the like. Usually, the respective polymer components are mixed at a predetermined ratio by a tumbler type blender, a Hensle mixer, a ribbon mixer, or the like, and then kneaded by an extruder or the like to obtain a pellet-shaped molding material. Using the material, a vibration damping resin molded product such as an engine under cover, a fender liner, and a dust cover is manufactured by injection molding or the like.

In addition, an antioxidant, an ultraviolet absorber, a lubricant, an antistatic agent, a nucleating agent, a pigment, a flame retardant,
Additives such as extenders and processing aids may be mixed.

[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 with a crystalline polybutylene as a vibration-damping-improving polymer. Sex PP
By adding and mixing, as shown in the examples below, compared with a PE-based polymer alloy containing only crystalline polybutylene, the vibration damping performance is not lowered (rather, it is improved), and the impact resistance is improved. In addition, usually, the hardness can be increased.

Therefore, the PE-based polymer alloy of the present invention is suitable as a molding material for a vibration-damping resin molded product such as an engine undercover, a fender liner, and a dust cover of a vehicle hit by a stepping stone or the like.

[0027]

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

A. Preparation of Test Specimens The mixture of each formulation shown in Tables 1 and 2 was prepared using a twin-screw extruder (L / D of each screw = 27, φ = 30 mm)
A pellet molding material was prepared by melt-kneading.

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

Polybutene (B): MI = 0.2 g / 1
0 minute, ethylene / butene-1 copolymer having an ethylene content of 9.1%.

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

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

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

Using the above pellet material, a test piece was molded by an injection molding machine. The injection conditions were as follows: cylinder temperature: 220 ° C., mold temperature: 40 ° C.

B. Test Method Each test piece was tested for the following items.

(1) Room Temperature Izod Impact Value A test was conducted on a test piece with a molded notch at an ambient temperature of 23 ° C. in accordance with ASTM D256.

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

(3) Rockwell hardness The hardness was measured according to JIS K7202.

(4) Flexural Modulus A test was performed in accordance with ASTM D790.

(5) Loss Coefficient A square plate having a length of 150 mm and a width of 3 mm and a thickness of 3 mm was prepared by injection molding.
Vibration was performed at 1 G, and the transfer function was measured. 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 converted to crystalline PP and crystalline polybutylene, and further to crystalline PP.
In each of the three-component examples in which is added, the impact resistance is significantly improved as compared with the respective two-component comparative examples in which only crystalline PE and crystalline polybutylene are used. It can be seen that is not reduced, but rather improved, and that the hardness is also generally increased.

When a copolymer with ethylene was used as the crystalline PP (Example 6), the impact resistance was superior to that when a homopolymer was used (Example 7). You can see that.

Table 2 shows physical data of each PE alone as a reference example.

[0045]

[Table 1]

[0046]

[Table 2]

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-296530 (JP, A) JP-A-55-137144 (JP, A) JP-A-53-140347 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) C08L 23/04

Claims (1)

(57) [Claims] 1. To 100 parts by weight of crystalline polyethylene
Crystalline polybutylene 5-200 parts by weight is blended Te braking
In a polyethylene polymer alloy for a vibration- absorbing resin molded product, the crystalline polybutylene has an ethylene content of 0.5 to 20%.
Ethylene-butene-1 copolymer, and the crystalline polypropylene is the crystalline polyethylene 100
A polyethylene-based polymer alloy, which is added and mixed in an amount of 1 to 100 parts by weight based on parts by weight .