JP2003128850A - High attenuation polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymer of high damping capacity having a sufficiently high stiffness and damping characteristics. SOLUTION: This polymer of high damping capacity is composed of 1-48 vol.% of plate-like graphite and the balance of polyethylene. As a preferred example, it contains 0.5-48 vol.% of at least one kind of filler composed of a glass fiber, glass bead, mica, a whisker and a carbon fiber. Furthermore, the plate-like graphite has 3-120 μm of a copper coated layer. In either case, it provides a preferable embodiment that can achieve the purposed of the invention more effectively.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polymer composite material (PMC: Polymer Ma) having high rigidity and high vibration damping performance.
trix composite), and more particularly to a polyethylene-based high damping polymer.

[0002]

2. Description of the Related Art Recently, polymer composite materials (PMC) have been used in various fields from the viewpoint of weight reduction. In particular, the entry into the fields of the automobile and aerospace industries is remarkable. Typical PMCs are ABS resin, polyamide (PA), polyethylene terephthalate (PE
Polymers such as T) and polybutyl terephthalate (PBT) are used as a mother phase, and fillers such as glass fibers, glass beads, mica, whiskers and carbon fibers are used for the reinforcing phase.

The performance required for such a PMC is generally high rigidity, high damping ability, wear resistance, weather resistance, etc., but in the fields of automobiles, acoustics and home appliances, high rigidity and high damping are provided. Efficiency, recyclability, and cost reduction are even more important. In particular, there is a demand for a high-rigidity / high-damping polymer that further improves the vibration damping characteristic of polymers.

[0004]

As described above, a PMC having a certain degree of high rigidity and vibration damping property has been developed. However, as a vibration damping material used in the fields of automobiles, acoustics and home electric appliances, the rigidity is high. Neither the vibration damping property nor the vibration damping property was still insufficient.

The object of the present invention is to solve the above problems,
The present invention aims to provide a high damping polymer having sufficiently high rigidity and vibration damping property.

[0006]

The high damping polymer of the present invention is characterized in that the plate graphite is 1 to 48% by volume and the balance is polyethylene.

In the present invention, by containing a predetermined amount of plate-like graphite, the local interlayer slip of the plate-like graphite as a filler and the stress relaxation mechanism of the polymer existing between the fillers adhered to the polymer work. The polymer has a high damping capacity. Further, this action and effect are remarkably exhibited by applying the present invention to a polyethylene-based polymer, and it is possible to obtain an unprecedented effect that it has excellent damping ability characteristics even in vibration in a low amplitude region.

As a preferred specific example, 0.5 to 48% by volume of a filler composed of at least one kind of glass fiber, glass beads, mica, whiskers and carbon fiber is contained, and the plate graphite is contained in an amount of 3 to 120.
A copper coating layer of μm has been provided. In either case, the present invention can be achieved more effectively, which is a preferred embodiment.

[0009]

The high damping polymer of the present invention is characterized in that its composition is composed of 1 to 48% by volume of plate-like graphite and the balance polyethylene. here,
The reason why the plate-like graphite as the filler is limited to 1 to 48% by volume is that if it is less than 1% by volume, the function of the damping mechanism is insufficient, and if it exceeds 48% by volume, the formability deteriorates. Further, the plate-like graphite is not particularly limited in its size as long as it is a plate-like graphite, but from the common sense, for example, the aspect ratio (diameter / thickness) is 10
Preference is given to using from 10 ⁶ graphite.

As a preferred embodiment, the high damping polymer having the above composition contains 0.5 to 48% by volume of a filler made of at least one of glass fiber, glass beads, mica, whiskers and carbon fiber. . These fillers are more effective in achieving high rigidity and high damping capacity. Here, the addition amount is 0.5 to 4
The content of 8% by volume is preferable because if it is less than 0.5% by volume, the function of the damping mechanism is insufficient, and if it exceeds 48% by volume, the formability deteriorates.

Further, as another example of the preferred embodiment, a plate-like graphite is provided with a copper coating layer of 3 to 120 μm.
By providing a copper coating layer, when mixing plate graphite into polyethylene, it is possible to prevent the shape from becoming smaller due to mutual wear and the like, and a stress relaxation effect is exhibited between the fillers, resulting in higher damping capacity. This is because it can be obtained. Here, it is preferable to set the thickness of the copper coating layer to 3 to 120 μm, because if it is less than 3 μm, it is difficult to prevent the destruction of the coating layer due to abrasion, and if it exceeds 120 μm, it is caused by interlayer slip of graphite. This is because the stress transmission becomes insufficient.

In the high damping polymer of the present invention having the above-mentioned constitution, in order to achieve high rigidity and high damping ability of the polymer material, the filler shape is plate-like, and the adhesiveness with the matrix phase is large. The two elements of are important. The damping mechanism is considered as follows.

FIG. 1 is a schematic diagram showing the state of the filler dispersed in the mother phase. In FIG. 1, (a) shows the case where the content of the filler in the matrix is small, and (b) shows the case where the content is large. When the content of the filler is low, the filler is simply dispersed in the matrix phase, so the damping capacity depends only on the shape of the filler and the polymer on the filler surface is in an unconstrained state, but shear deformation This causes the conversion of vibrational energy into thermal energy. The damping capacity in this case does not become so large.

However, when the content of the filler is increased, the polymer is bound between the two plates, so that the energy loss due to the shear deformation of the polymer becomes extremely large. Further, as shown in FIG. 2, there are cases where (a) the adhesion between the filler and the mother phase is excellent, and (b) where the adhesion between the filler and the mother phase is poor. The better the adhesiveness, the larger the stress transmission, and the greater the damping capacity. Further, it is considered that energy loss due to shear deformation of the polymer alone is not sufficient to obtain a larger damping capacity. In the present invention, by using plate-shaped graphite,
In addition to shear deformation of polymer, energy loss due to slip deformation between graphite layers also contributes to high damping capacity.

An actual example will be described below. First,
Plate-shaped graphite was prepared. The size of the plate-like graphite was the size of the plate-like portion of 180 × 180 μm and 350 × 350 μm, and the thickness was 20 μm. The surface of the plate-like graphite was coated with aminosilane and epoxy resin in order to improve the adhesion to the base material. The amount of plate-like graphite added to polyethylene is 0, 0.5, 1, 1
It was set to 9 kinds of 0, 20, 30, 40, 48 and 60 volume%. Then, plate-like graphite and polyethylene were mixed, and the mixture was injection-molded. The conditions of injection molding were a cylinder temperature of 250 ° C., a mold temperature of 80 ° C., and a processing pressure of 4.9 × 10 ^{−2 to} 0.15 GPa.

The shape of each injection molded body is 100 × 60
It was × 10 mm. By processing this, the total length is 100 m
m, the gripping part is a 6 × 6 mm prism, and the measuring part has a diameter of 7 mm
Thus, a twist test piece of a round bar having a length of 20 mm was obtained. The damping capacity and the rigidity of the obtained torsion test pieces having different amounts of graphite added were measured. The damping ability and the rigidity were measured using a torsion pendulum type measuring device, and the damping ability was calculated from a free damping waveform. 1 x 10
Table 1 below shows the results of obtaining the values of the damping capacity of the strain- ³ under strain amplitude.

[0017]

[Table 1]

From the results shown in Table 1, it is understood that high damping capacity and high rigidity can be obtained when the addition amount of the plate-like graphite is 1 to 48% by volume.

Next, the strain amplitude dependence of the damping capacity was determined for a torsion test piece in which the addition amount of plate-like graphite was 20% by volume. The strain amplitude dependency of the damping capacity was measured in the range of the maximum surface shear strain amplitude of 1 × 10 ^{−5 to} 9 × 10 ⁻³ . The results are shown in Fig. 3.

FIG. 3 shows pure Mg, a general-purpose material, for comparison.
Mg alloy (AZ63A), a typical Mg-based damping alloy
K1X1 alloy (alloy developed by Weissmann et al., USA)
And an MCM alloy (an alloy developed by the present inventors,
MCM-D is a die casting alloy, MCM-C is cast
Alloy), flake graphite cast iron (FC20), polymer material
6-nylon (PA), which has the largest damping capacity,
LBT-free PBT (polybutylene terephthalate),
PC (Polycarbonate), PET (Polyethylene Tele)
Phthalate) and PE (polyethylene), and ceramic
Mix Si _ThreeN_FourData are also shown. Also, 20
PBT containing volume% glass flakes (PBT-GF4
015) and PET containing 20% by volume of glass flakes
(PET-GF4015) is also shown for reference. Na
The poly containing 20% by volume of plate graphite of the present invention
Ethylene was described as PE-G20.

From the results shown in FIG. 3, the PE-G20 of the present invention is an ideal high damping material having the largest damping ability among polymer materials and having extremely large damping ability in the low strain amplitude region. I know there is.

[0022]

As is apparent from the above description, according to the present invention, since a predetermined amount of plate-like graphite is contained, the plate-like graphite as a filler has a local inter-layer slip and a close contact with the polymer. The polymer has a high damping capacity due to the stress relaxation mechanism of the polymer existing between the fillers. Further, this action and effect are remarkably exhibited by applying the present invention to a polyethylene-based polymer, and it is possible to obtain an unprecedented effect that it has excellent damping ability characteristics even in vibration in a low amplitude region.

[Brief description of drawings]

FIG. 1 (a) and (b) are schematic diagrams showing a dispersed state of a filler in a mother phase.

2 (a) and (b) are schematic diagrams showing the adhesiveness between a filler and a mother phase, respectively. FIG.

FIG. 3 is a graph showing strain amplitude dependence of damping capacity in the high damping polymer of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Fuyasu             2641 Yamazaki, Noda, Chiba Prefecture Tokyo University of Science, Science and Engineering             Faculty of Mechanical Engineering F term (reference) 3J048 AA01 BA23 BD01 BD04 EA01                 4J002 BB031 DA026 DJ057 DL007                       FA016 FA047 FA067 FA087                       FD017 GT00

Claims (3)

[Claims] 1. A high damping polymer, characterized in that the plate-like graphite is 1 to 48% by volume and the balance is polyethylene. 2. The high damping polymer according to claim 1, containing 0.5 to 48% by volume of a filler comprising at least one kind of glass fiber, glass beads, mica, whiskers and carbon fiber. 3. The plate graphite has a thickness of 3 to 120 μm.
The high damping polymer according to claim 1 or 2, further comprising a copper coating layer.