JP2002080660A - Vibration damping material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration damping material excellent in both heat resistance and vibration damping property as well as in molding property. SOLUTION: The vibration damping material is mainly composed of an olefinic resin, obtained by dynamically crosslinking an ethylene/propylene/diene- based rubber while melt-kneading a polypropylene with ethylene/propylene/diene- based rubber, and a tackifier. Though an olefinic resin of this kind is inferior in vibration damping property in itself, incorporation of a tackifier therewith imparts excellent vibration damping property to the resin. As this olefinic resin is thermoplastic, it does not require vulcanization nor a curing reaction and is readily moldable. For example, it can be mass-produced by an injection molding method. Moreover, it does not contain sulfur nor a vulcanizing agent such as an amine, it does not cause a trouble such as corrosion or the like of a material to which it is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping material used in automobiles, OA equipment, electric / electronic equipment, precision equipment, buildings, ships, etc., which are required to have vibration damping properties and heat resistance.

[0002]

2. Description of the Related Art In the above-mentioned fields, in recent years, with higher precision and higher performance of equipment,
Reduction of vibration and noise has become a major issue. These countermeasures are also regarded as important as one of the environmental problems.

Conventionally, rubber or gel-like materials having a low elastic modulus have been used to insulate equipment from vibration sources. However, the magnitude of the vibration at the resonance frequency (resonance magnification) becomes extremely large, and there is a concern that the device may be damaged. On the other hand, the damping material is a material that easily attenuates mechanical energy applied from the outside inside, and can suppress the above-described resonance magnification to a low level. In particular, high damping and high interest have been paid to polymer damping materials that are light in specific gravity and easy to mold.

When a stress is applied to a polymer material, the material is deformed, and when the stress is removed, the entanglement of the stretched polymer chain tends to return to its original state. This intramolecular or intermolecular motion generates frictional heat, which is dissipated to the outside, resulting in internal energy loss (attenuation). As described above, the polymer damping material is a material that converts mechanical vibration energy into heat energy and attenuates the vibration energy itself inside the material.

[0005] A value that serves as a measure of damping performance is a loss coefficient (hereinafter referred to as tan δ). This can be obtained from a storage elastic modulus (hereinafter, referred to as G ') representing a spring force and a loss elastic modulus (hereinafter, referred to as G ") representing a viscous force, and the relationship of tan δ = G" / G' is obtained. is there. In general, when observing the storage elastic modulus, the loss elastic modulus, and the temperature dependence of the loss coefficient of a polymer material, the loss coefficient shows a maximum at a secondary transition point of a polymer at which the storage elastic modulus is greatly reduced, that is, a so-called glass transition point. That is, when designing a polymer damping material, it is important that the glass transition point exists near the use temperature.

Most of conventional vibration damping materials are made of thermosetting resins such as vulcanized rubber such as butyl rubber and norbornene rubber, and synthetic rubber such as silicone rubber. However, in a vulcanized rubber, sulfur or the like as a vulcanizing agent (crosslinking agent) may remain in the material, forming a sulfide with a metal part of an electronic device or the like and corroding. In the case of silicone rubber, there is also a problem that electric contact failure occurs due to volatilization of unreacted low molecular weight siloxane.

[0007] These resins require tens of minutes to several hours for vulcanization and curing reactions during molding, and in some cases also require a secondary vulcanization step, and have a problem of poor mass productivity. Further, thermosetting resins have a disadvantage that the reaction is essentially irreversible and cannot meet the demand for material recycling.

Further, as the performance required in the above-mentioned field, not only vibration suppression but also heat resistance is required. In particular, with the recent increase in density and output of equipment,
There is a further need for vibration damping materials that can be used even at high temperatures.
Heat resistance is generally evaluated based on the set (compression set) characteristics and the presence or absence of bleed of low molecular components. In particular, low-hardness vibration damping materials for lightweight objects such as cooling fans and small motors are plasticizers. And a large amount of a softening agent, the deterioration of compression set characteristics at high temperatures and the problem of bleeding were unavoidable.

The present invention has been made in view of the above problems, and has as its object to provide a vibration damping material which is excellent in both heat resistance and vibration damping property and has good mass productivity.

[0010]

Means for Solving the Problems and Effects of the Invention The present invention according to claim 1, which has been made to solve the above problems, comprises a polypropylene (hereinafter referred to as PP) and ethylene-
While melt-kneading a propylene-diene rubber, ethylene-
It is characterized by comprising, as main components, an olefin resin obtained by dynamically cross-linking a propylene-diene rubber (hereinafter referred to as EPDM) and a tackifier.

[0011] PP may be a block copolymer or a random copolymer in addition to a homopolymer, and the copolymerized monomers are ethylene, 1-butene, 1-pentene and 1-pentene.
Hexene, 1-octene, 3-methyl-1-pentene,
4-Methyl-1-pentene and the like are used.

EPDM is a terpolymer of ethylene, propylene and some diene, and the diene component includes 1,3-cyclopentadiene, 1,4-cyclohexadiene, 1-4-hexadiene, 1,5 -Cyclooctadiene, 1,6-octadiene, 1-methyl-1,5
-Cyclooctadiene, 2-methyl-1,4-pentadiene, 3,7-dimethyl-1,6-octadiene, 5-
Methyl-1,4-hexadiene, 5-ethylidene-2-
Norbornene, 5-methylene-2-norbornene and the like can be used.

The weight ratio between PP and EPDM is appropriately selected within a range that does not impair the physical properties and moldability of the material.
If the weight ratio is not more than 20%, it is difficult to lower the hardness of the whole material. EPDM is at least partially
Preferably, it is completely crosslinked. By doing so, not only the heat resistance, weather resistance, and chemical resistance are remarkably improved, but also it becomes easy to be uniformly dispersed as a fine filler in the PP matrix.

In the case of dynamic crosslinking, a crosslinking agent suitable for EPDM is used. Examples of the type of the crosslinking agent include a peroxide type, a metal oxide type, and a thermosetting resin type. Here, the use of a sulfur type, an amine type or other corrosive crosslinking agents should be avoided. Although these olefin-based resins are essentially inferior in vibration damping properties, they have excellent vibration damping properties by adding a tackifier. Many tackifiers generally have a glass transition point higher than room temperature. In other words, if a tackifier with good compatibility with the olefin resin is selected, it is possible to freely control the low glass transition point inherent in the olefin resin and shift it to around the operating temperature as a vibration damping material. It becomes.

Examples of the tackifier include rosin, modified rosin, rosin ester, terpene resin, terpene phenol resin, aromatic hydrocarbon modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, and aromatic type Examples include petroleum resins, cumarone / indene resins, styrene resins, cyclopentadiene resins, phenol resins, and xylene resins.

These tackifiers have a molecular weight of 100 to 3
It is in the range of about 000, and exhibits a plasticizing effect on the olefin resin. Conventionally, vibration-damping materials for lightweight materials required the addition of a large amount of plasticizers and softeners to reduce hardness, but use resin-like materials that fall into the category of oligomers as described above. If so, low hardness can be achieved without deterioration of compression set characteristics at high temperature or bleeding.

[0017] The vibration damping material thus compounded is excellent in heat resistance, cold resistance, weather resistance, heat aging resistance, electrical insulation and chemical resistance as a thermoplastic resin material, and has a small specific gravity. There are features. Furthermore, since it is thermoplastic in nature and rich in moldability, it is possible to mass-produce products by, for example, injection molding. In addition, recyclability can be expected such that sprues, runners and defective products can be reused during molding. Moreover, there is no problem such as corrosion because no sulfur or amine vulcanizing agent is used.

According to a second aspect of the present invention, in the vibration damping material according to the first aspect, the tackifier is a hydrogenated terpene resin. What is hydrogenated terpene resin?
Isoprene rule the (C ₅ H ₈₎ terpene resins are polymers of terpenes based monomers _n is obtained by adding hydrogen. Heat resistance (aging) resistance, weather resistance,
Furthermore, the odor and hue have been greatly improved.

The glass transition point of the hydrogenated terpene resin is generally higher by at least 50 ° C. than the glass transition point of the olefin resin. Moreover, since the polarity is low and the compatibility with the olefin resin is good, it is possible to greatly improve the glass transition point of the entire system. Details will be shown in the experimental examples described later,
When the tackifier is a hydrogenated terpene resin, it becomes a vibration damping material exhibiting practical performance in various properties such as vibration damping properties and heat resistance.

Incidentally, contrary to this, a tackifier other than the hydrogenated terpene resin may be used. For example, when a certain type of terpene resin is used as a tackifier, the heat resistance is inferior to that of a vibration damping material using a hydrogenated terpene resin, as described later, but the vibration damping material is excellent.

According to a third aspect of the present invention, in the vibration damping material according to the first or second aspect, the weight ratio of the tackifier in the vibration damping material is 40 to 65%. And With such a compounding ratio, a particularly excellent vibration damping property is obtained while maintaining the heat resistance (also described later).

[0022]

Embodiments of the present invention will be described below with reference to the drawings. [Experimental example 1] As a dynamically crosslinked olefin resin, J
A type A durometer according to IS K 6253 standard having a durometer hardness of A55 and a 25% compression set according to JIS K 6262 standard of 30% or less at 100 ° C. for 168 hours was used.

The following three kinds of tackifiers were prepared. That is, hydrogenated terpene resin (molecular weight 70
0), terpene resin (molecular weight 800), and alicyclic petroleum resin (molecular weight 610). The olefin-based resin and the tackifier were kneaded at a weight ratio of 50:50 to prepare three types of samples. More specifically, first, the raw materials are premixed with a mixer for about 20 minutes, and an AS30 type twin screw vented extruder (L / D = 2) manufactured by Nakatani Machinery Co., Ltd.
8) and kneaded and extruded under the condition of a cylinder set temperature of 170 to 200 ° C. The obtained lump was compression-molded using a tabletop test press molding machine at a mold temperature of 200 ° C. and a pressure of 30 MPa to obtain a sheet-like sample having a thickness of 2 mm. Table 1 shows the physical property data of each sample.

[0024]

[Table 1]

For measurement of the tan δ value and the elastic modulus at room temperature (25 ° C.), a dynamic analyzer RD manufactured by Rheometrics, which is a measuring device based on a non-resonant type forced vibration method, is used.
A-II was used. A parallel plate was used for the measurement. The conditions were set at a strain amplitude of 1.0% or less, a frequency of 1 Hz, and a heating rate of 4.0 ° C./min, and the temperature dependence of G ′, G ″ and tan δ was examined in the range of −60 to 200 ° C.

For the compression set, see JIS K
Based on the 6262 standard, the permanent set at 25% compression under the conditions of 100 ° C. and 22 hours was determined. Practically, this value is desired to be 50% or less. The resonance frequency and the resonance magnification were measured by a vibration test using a vibrator. After fixing the test piece at the four corners of the jig and fixing it on a vibration table, the acceleration is kept constant and the frequency is swept from 5 to 500 Hz for 2.5 minutes to cause resonance. The vibration at this time was detected by an acceleration pickup, and a resonance curve was created based on the data to calculate a resonance magnification.

As for the loss coefficient, a resonance frequency f ₀ from the resonance curve and a frequency width Δf at which the resonance curve is reduced by 3 dB from the maximum value (resonance magnification) of the resonance curve are obtained.
δ = Δf / f ₀ . As shown in [Table 1],
Example 1 using hydrogenated terpene resin as tackifier
, The tan δ value at 25 ° C. was the largest. Further, the elastic modulus (G ') was the smallest and had low hardness. Further, the sample using the hydrogenated terpene resin had a permanent strain rate of 39.25% under a condition of 100 ° C. and 22 hours under 25% compression.
It has an excellent heat resistance of 9%. [Table 1]
Although it was not shown in the above, it showed a very excellent value of 44.8% in the compression set test of 168 hours.

Also, as a result of the vibration test, the resonance magnification was 2.2 dB, and the loss coefficient was 1.72, which was a very high performance value. On the other hand, in Example 2 using the terpene resin, the tan δ value and the elastic modulus at 25 ° C., and the resonance magnification and the loss coefficient in the vibration test showed excellent values close to those of the hydrogenated terpene resin. However, the permanent set at 25% compression at 100 ° C. for 22 hours or 168 hours is slightly inferior to that of the hydrogenated terpene resin.

In Comparative Example 1 using an alicyclic petroleum resin, the vibration damping property also showed an excellent value. However, there is a problem that the elastic modulus is as high as 4.0 MPa and the hardness is increased. Further, it was difficult to pull the strand during kneading and extrusion, and there was a concern about kneading workability and compatibility of the material itself.

EXPERIMENTAL EXAMPLE 2 In the case of using a hydrogenated terpene resin as a tackifier, the weight ratio in the vibration damping material was changed to 0, 20, 40, 50, and 65%, and the same as in Experimental Example 1. A sheet-like sample was obtained by a suitable method. Table 2 shows the physical property data of each sample. Here, Example 3 is the value of the olefin-based resin itself without the addition of the hydrogenated terpene resin.

[0031]

[Table 2]

As shown in Table 2, when the weight ratio of the hydrogenated terpene resin is 40% or more, both the resonance magnification and the loss coefficient exhibit excellent values. If the weight ratio is 65% or less, the compression set under the conditions of 100 ° C. for 22 hours is also about 50% or less, and the material has both vibration damping property and heat resistance.

For the materials of Examples 1, 3, and 6, the glass transition point was measured using a differential scanning calorimeter manufactured by TA Instruments. The measurement was performed at a heating rate of 2 ° C / min
The measurement was performed by observing relaxation of physical properties under the conditions described above and detecting heat flow at the transition temperature. According to this, the glass transition point of the olefin resin of Example 3 itself was -4.
It was found that although the temperature was 2.3 ° C., the temperature was significantly shifted to −8.5 ° C. by 50% by weight of the hydrogenated terpene resin of Example 1, and to 27.4 ° C. by 65% by weight of Example 6.

The phase structure of the material of Example 1 was observed using a transmission electron microscope (TEM) manufactured by Hitachi in order to confirm compatibility. After embedding the sample, a thin section of about 100 nm thickness was prepared in a frozen state and stained with RuO ₄ .
The phase structure was photographed at an accelerating voltage of 200 kV at a magnification of up to 300,000. As a result, the continuous phase is composed of the EPDM phase, the hydrogenated terpene resin is finely and uniformly dispersed in the EPDM phase in a size of about 50 nm, and the crystallized PP phase is about 2 nm.
A dispersed structure having a size of about 5 μm was formed (see FIG. 1). A lamellar structure is observed in the crystallized PP phase, and it can be seen that the hydrogenated terpene resin is partially incorporated between the lamellas.

As described above, according to the vibration-damping material of the present invention, it was possible to obtain excellent heat-damping properties despite excellent heat-resistance. This vibration damping material contains a tackifying resin that acts as a polymeric plasticizer, which improves the fluidity at the time of melting, so that the material is rich in moldability. For example, products can be mass-produced by injection molding. Further, since there is no need to add a large amount of a plasticizer or a softening agent, there is little problem of change with time, such as settling and bleeding of low molecular components. Furthermore, since the material is essentially thermoplastic, a vulcanization or curing step is not required, and it has recyclability. Further, since no sulfur or amine vulcanizing agent is used, there is no problem that the object to be applied is corroded.

Therefore, it can be widely used as a vibration damping material for equipment in the following fields. In other words, automobiles, office automation equipment, electrical and electronic equipment, precision equipment, medical care,
Sports, architecture, ships, railways, industrial machinery, aerospace, etc. The embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments and can be implemented in various embodiments.

For example, olefin resins and tackifiers other than those described above may be used. Moreover, you may mix | blend the following fillers as needed. For example, as an amorphous filler, heavy calcium carbonate, light calcium carbonate, natural silica, synthetic silica, kaolin, clay, titanium oxide, barium sulfate, zinc oxide (zinc white), aluminum hydroxide, aluminum oxide (alumina), water Magnesium oxide, as plate-like filler, talc, mica, glass flake, synthetic hydrotalcite, needle-like filler, wollastonite, potassium titanate, basic magnesium sulfate, sepiolite, zonotlite, aluminum borate, as spherical filler, Glass beads, silica beads, glass (silica) balloons, and functional fillers such as metallic conductive fillers, non-metallic conductive fillers, carbon-based conductive fillers, magnetic fillers, piezoelectric, pyroelectric fillers, slidable fillers, In addition, fibrous Organic as chromatography, inorganic, also a metal of various fibers can be blended.

Other additives include a plasticizer,
Softener, stabilizer, antioxidant, ultraviolet absorber, foaming agent,
Improvements in properties can be expected by using flame retardants, antistatic agents, lubricants, coloring agents, antibacterial agents, surface treatment agents, polymer modifiers, and the like. There is also no particular limitation on the method of mixing and kneading these materials. For example, a mixing roll, a Banbury mixer, a pressure kneader, or a high-shear mixer can be used as a batch-type kneading apparatus, and a single-screw extruder, a twin-screw extruder, a KCK extrusion-kneader, or the like may be used as a continuous kneading apparatus. .

[Brief description of the drawings]

FIG. 1 is a transmission electron micrograph of a vibration damping material of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C09J 123/10 C09J 123/10 4J040 123/16 123/16 201/00 201/00 C09K 3/00 C09K 3 / 00 P E04B 1/98 E04B 1/98 B F16F 1/36 F16F 1/36 C 15/08 15/08 D (72) Inventor Ryo Takagi 24-24-15 Chiyoda, Naka-ku, Nagoya City, Aichi Prefecture Kitagawa Kogyo Inside (72) Inventor Teruaki Yuoka 2-24-15 Chiyoda, Naka-ku, Nagoya-shi, Aichi F-term (reference) in Kitagawa Industry Co., Ltd. 2E001 DD05 DF07 DG01 FA24 GA24 HD11 JD02 LA16 3J048 AA01 AC01 AC05 AD05 BA11 DA01 EA13 EA38 3J059 AA08 AB01 BA63 GA01 GA21 GA41 4F070 AA15 AA16 AC74 AC96 AE11 FA03 FA08 FA17 FB06 FC05 GA05 GA06 GB08 4J002 AF02Y BA00Y BA01Y BB12W BB14W BB15W BB15X BC02Y BK00Y BP02W CE00 0 4J040 BA191 BA192 BA201 BA202 DA091 DA092 DA122 DB021 DB022 DK011 DK012 DK021 DK022 DN031 DN032 EB021 EB022 EB081 EB082 JA09 KA26 LA06 LA08 NA02 NA05 NA12 NA15 NA16 NA19

Claims (3)

[Claims] An olefin resin obtained by dynamically cross-linking an ethylene-propylene-diene rubber while melt-kneading a polypropylene and an ethylene-propylene-diene rubber, and a tackifier as a main component. Damping material. 2. The vibration damping material according to claim 1, wherein the tackifier is a hydrogenated terpene resin. 3. The damping material according to claim 1, wherein the weight ratio of the tackifier in the damping material is 40.
A vibration damping material characterized by being 65% or less.