JPH10298354A - Highly damping material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject material having a large energy absorbability, capable of showing an excellent noise absorbability, vibration damping property, vibration resistance, impact absorbability, vibration-deducing property, and ageing stability, and useful for noise barriers, etc., by dispersing a dielectric substance in a specific rubber material or elastomer material. SOLUTION: This highly damping material is obtained by dispersing (A) an organic low molecular dielectric substance or ferrodielectric substance (e.g. a crosslinking accelerator) in (B) a rubber material or elastomer material having polar side chains (e.g. chlorinated polyethylene, a polyvinyl chloride-based thermoplastic elastomer). The material is obtained e.g. by kneading the component A with the component B, thermally molding the kneaded product at a temperature of 100-250 deg.C and subsequently forming a constrained layer on the surface of the obtained material. Thereby, the crystallization of the component A can be prevented, and the deterioration of the damping property with time can effectively be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-attenuation material and a method for manufacturing the same, and more particularly, to vibration and noise applied to a sound insulation wall of an acoustic room, a sound insulation partition of a building structure, a sound insulation wall of a vehicle, and the like. The present invention relates to a high damping material as a vibration damping material and a soundproofing material, and a manufacturing method for increasing the durability thereof.

[0002]

2. Description of the Related Art A polymer material as a high damping material of this type can be regarded as a Voigt model which is a typical viscoelastic body shown in FIG. According to the Voigt model, the mass is modeled as the mass of the polymer material, the spring is modeled as an elastic component, and the dashpot is modeled as a viscous component.

[0003] If a minute material portion of a polymer material is captured by this model, the polymer material is formed by connecting the model innumerably. Complex sinusoidal strain (ε ^* ) for minute parts of material
Which results in a complex sinusoidal stress (σ ^* ). By taking these ratios, the complex elastic modulus (E ^* )
Is given by the following equation: Complex elastic modulus (E ^* ) = complex sinusoidal stress (σ ^* ) / complex sinusoidal strain (ε ^* )

The real part of the complex elastic modulus (E ^* ) is defined as the storage elastic modulus (E ') related to the elastic properties of the material, and the imaginary part is the loss related to the viscous properties of the material. The modulus of elasticity (E ") is defined, and by taking these ratios, the loss coefficient (tan δ) is given by the following equation: loss coefficient (tan δ) = loss elastic modulus (E ″) / storage elastic modulus (E ′). The loss coefficient (tan δ) is one of the factors that determine the damping and soundproofing characteristics. The higher this value is, the more the mechanical energy is absorbed or released as electric or thermal energy.
It is known that it has excellent sound absorption characteristics and vibration damping characteristics.

In such a technical background, as a polymer material having a high damping property, for example, a filler (mica) is added to a base polymer composed of a polymer alloy or a polymer compound having a polymer network structure (IPN technology). Etc.) and a composite material processed by adding a plasticizer are known. Various rubbers, elastomers, resin materials, etc. are used as the base polymer, and the damping mechanism is such that the entanglement between the main chain and the side chain once occurs when the stress generated when strain is given by sound waves or vibration is removed. Unraveled objects exhibit the behavior of returning to their original state.However, this kind of movement is caused repeatedly to generate friction between molecules, and the mechanical energy due to the sound waves and vibration is converted to heat energy to attenuate the vibration. It is.

As a material having a high damping characteristic, another two-layer structure in which polyvinylidene fluoride (PVDF) is processed into a film shape and aluminum is deposited on the surface thereof as a polymer-based piezoelectric material is the Tokyo Institute of Technology. Has already been studied by Masao Sumita and others, and research toward realization has been done by each company. According to this film, when a sound wave passes through this film, a part of the vibration energy of the sound wave is converted into electric energy by a piezoelectric effect,
By connecting an electrical resistor to the film, electrical energy is converted to thermal energy and the sound waves are attenuated, thereby attenuating vibration.

[0007]

However, the above-mentioned polymer-based composite material has a drawback that the loss factor (tan δ) is low. The value of various rubber materials (hard rubber, nitrile rubber, urethane rubber, filled rubber) is 0.3
About 1.0, polymer resin materials (polystyrene, polyisobutylene, sulfide rubber, polyvinyl chloride, vulcanized, polymethyl methacrylate, plasticized polyvinyl chloride,
(Polyester, polytetrafluoroethylene) has a value of about 1.0 to 2.0.

The mechanism for converting mechanical energy into thermal energy by friction between molecules to attenuate vibrations includes the bonding force and shape of the polymer chain, the structure of the main chain and the side chain, the crosslinking density, The damping capacity is limited due to the effect of the agent.

Further, according to the above-mentioned piezoelectric material, the resistance, inductance or negative capacitance is controlled by using an external circuit or applied by using an active control circuit so that electric energy is converted into heat energy. It is necessary to control the viscoelasticity by the feedback voltage, the phase difference between the detected stress and strain, and the applied voltage. Therefore, when the piezoelectric material is applied as a soundproofing / damping material, various electric elements are required, and the operation thereof must be controlled.

On the other hand, in order to realize a better soundproofing / damping function, in the case of solid-borne sound, a high loss factor (tan δ) is obtained by suppressing the sound radiated from a vibrating object.
If a thin film material capable of responding to a strain of about 10 ^-6 is realized by absorbing the sound generated in the low frequency region in the case of gas-borne sound, a more excellent high-attenuation material will be realized. It has been found that it can be obtained.

The problem to be solved by the present invention is that it has a large amount of energy absorption, is excellent in sound absorbing characteristics, vibration damping characteristics, vibration damping characteristics, shock absorbing characteristics, etc., and avoids deterioration of damping performance due to aging. An object of the present invention is to provide a high-damping material having excellent durability and a method of manufacturing the same.

[0012]

According to the present invention, there is provided a high-attenuation material comprising a low-molecular organic dielectric substance or a ferroelectric substance, a rubber material or an elastomer material having polar side chains. The main point is that they are dispersed in the same manner.

As the material of the "organic low molecular weight dielectric substance or ferroelectric substance", a crosslinking accelerator (for example, sulfenamide type, thiourea type, thiuram type, thiazole type, guanidine type, aldehyde-ammonia type) Aldehyde-amine-based, dithiocarbamate-based, xanthate-based, and mixing accelerators). In addition, the dipole moment (μ) is 1 Deb
y or more organic low molecular weight dielectric substances (eg, ethylene carbonate, propylene carbonate, formamide, dimethylformamide (DMF), N-methylformamide (NMF),
N-methylacetamide (NMAC)), liquid crystals exhibiting an electrodynamic effect (shear-flow organic polarization) (for example, Schiff base compounds), rubber aging inhibitors, resin stabilizers, and ultraviolet absorbers.

On the other hand, rubber-based materials having polar side chains include modified natural rubber, grafted natural rubber, cyclized natural rubber, chlorinated natural rubber, chloroprene rubber (CR), and acritonitrile-butadiene rubber (NBR). , Carboxylated nitrile rubber, nitrile rubber / vinyl chloride resin blend, nitrile rubber / EPDM rubber blend, brominated butyl rubber, chlorinated butyl rubber, ethylene-vinyl acetate rubber (EVA), acrylic rubber (ACM, ANM), ethylene-acryl rubber, Chlorosulfonated polyethylene,
Examples thereof include chlorinated polyethylene, epichlorohydrin rubber, epichlorohydrin-ethylene oxide rubber, methyl silicone rubber, vinyl-methyl silicone rubber, phenyl-methyl silicone rubber, fluorinated silicone rubber, and fluororubber.

Examples of the elastomer-based material having a polar side chain include polyvinyl chloride-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, and polyamide-based thermoplastic elastomer.

As a dispersion state, a dielectric substance may be directly blended with a rubber material or an elastomer material, but these materials are kneaded with each other and bonded (pendant) to a side chain by a crosslinking reaction or the like. Even better.

In this case, it is desirable that the volume ratio of the organic low molecular weight dielectric substance or the ferroelectric substance to the rubber material or elastomer material having a polar side chain is 0.3 or more. In this case, if the amount of chlorine, molecular weight, and amount of crystal are adjusted, the mechanical resonance frequency (Wn) and the electric resonance frequency (W
e) and the loss factor (tan δ)
To infinity. Then, the obtained high damping material is apparently solid, but the physical properties are completely viscous.

It is preferable that the organic low molecular weight dielectric substance or the ferroelectric substance is dispersed in the rubber material or the elastomer material in an amorphous state. When the organic low molecular weight dielectric substance or the ferroelectric substance is crystallized, the damping performance is greatly reduced.

Further, the present invention provides a step of kneading an organic low-molecular-weight dielectric substance or a ferroelectric substance with a rubber material or an elastomer material having a polar side chain; The gist of the present invention is to provide a step of heat-forming at a temperature of 250 ° C. and to provide a constraining layer of a silicon material on the surface of the material having undergone the heat-forming step.

Through such a heat treatment step and by providing a constraining layer of a silicon material on the surface of the material, crystallization of the organic low-molecular-weight dielectric substance or ferroelectric substance is prevented, and attenuation due to aging is prevented. Performance degradation will also be avoided.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. First, the following Table 1 shows a list of the material compositions of the samples (samples) subjected to the present invention.
As the polymer material, resin-based chlorinated polyethylene (CPE), rubber-based acrylonitrile-butadiene rubber (NBR), nitrile rubber (NR), and chloroprene rubber (CR) are used. As described above, two kinds of N, N-dicyclohexylbenzothiazyl-2-sulfenamide (Sancellar DZ) and N, N'-dibutylthiourea (Sancellar BUR) were adopted as dielectric substances "A" and "B", respectively.

[0022]

[Table 1]

Samples 1 to 6 of the product of the present invention are all manufactured as follows. That is, chlorinated polyethylene (C
PE) or the like and a predetermined dielectric substance ("A" or "B") are kneaded and compounded, and the kneaded material is heated and molded in a predetermined mold at 100 to 250C for about 10 minutes. It is. Temperature conditions are below the melting point of the polymer material,
Above the melting point of the dielectric material is employed. As a result, this material has a non-crystalline structure, and needle-like crystals have disappeared. Then, a silicone resin film is adhered to the surface of the material immediately after the sheet is formed (heat-formed), thereby suppressing the material from crystallizing from the surface.

Table 2 below shows the peak value of the loss coefficient (tan δ) and the peak temperature of the product of the present invention (Samples 1 to 6 shown in Table 1) in comparison with the single product. . First, samples 1 and 2 of the product of the present invention and chlorinated polyethylene (C
As can be seen from the comparison with the PE alone, the peak value of the loss factor (tan δ) is increased by blending the dielectric substance (in this case, the dielectric substance “A”). The peak value of Sample 1 is about twice as large as that of the single product, and that of Sample 2 is about 2.5 times that of the single product. In addition, the peak temperature of Sample 1 was 22 ° C. compared to 0 ° C. for the single product.
° C and the temperature of Sample 2 were increased to 24 ° C, indicating that a good loss factor (tan δ) was obtained at room temperature. Furthermore, although the peak value of Sample 3 is not so high, it exhibits a very broad distribution peak as described later, and thus can be used in a wide temperature range.

[0025]

[Table 2]

Also, in comparison between the single product of acritonitrile-butadiene rubber (NBR) and the compound containing a dielectric substance (Sample 4 of the present invention), the loss coefficient was increased by adding the dielectric substance to the rubber material. It can be seen that the peak value of (tan δ) has increased. The peak value of tan δ was 2.2 for the single product, whereas the peak value of sample 4 was 3.
It is about 1.4 times that of 1.

Also, nitrile rubber (NR) alone (tan)
δ = 0.8, peak temperature of 20 ° C.) and a compound obtained by adding a dielectric substance thereto (Sample 5 of the present invention).
It can also be seen that the peak value of the loss coefficient (tan δ) is increased by blending the dielectric material with the rubber material. In this case, the peak value of Sample 5 is 2.4, which is about three times that of the single product. In addition, chloroprene rubber (C
R) Single product (tan δ = 1.2, peak temperature -30 ° C)
And a mixture thereof with a dielectric substance (Sample 6 of the present invention)
Also in comparison with the above, the peak value of the loss coefficient (tan δ) is increased by adding the dielectric substance to the rubber material, but the peak value is 2.2, which is slightly lower.

FIG. 1 shows the temperature (° C.) on the horizontal axis and the loss factor (tan δ) on the vertical axis, and shows the results for each sample 1 and 2 of the product of the present invention.
3 is a graph showing temperature-tan δ characteristics for Nos. 3 to 6. As shown in FIG. 1, the loss coefficient (t
The temperature (° C.) at which the peak value of an.delta.) differs for each sample, and the peak value of the loss coefficient (tan.delta.) also differs for each sample. Therefore, it is effective to use different materials according to required characteristics. In particular, Sample 3 has a characteristic of exhibiting a very broad distribution peak.

For example, in a refrigerated environment, samples 4 to
6 is a suitable high-attenuation material, and in a room temperature environment, samples 1, 3, and 4 are suitable high-attenuation materials, and a sound insulation wall of an acoustic room, a sound insulation partition of a building structure, a sound insulation wall of a vehicle. And so on.
In particular, the peak value of the loss coefficient (tan δ) of the sample 3 is low, but since the value is stable over a wide temperature range of about 20 to 50 ° C., the temperature is higher than room temperature, for example, a vehicle. It can be said that it is a high damping material suitable for use in drive control units of various industrial equipment.

From the above, Samples 1 to 5 of the present invention were obtained.
As a result of comprehensive evaluation of Sample No. 6, Sample 1 was marked with “◎” (very good), Sample 2 was marked with “◎” (very good), Sample 3
Is “◎” (very good), sample 4 is “◎” (very good), sample 5 is “△” (slightly poor due to weak side chain polarity), and sample 6 is “○” (good). ) Was evaluated.

FIG. 2 shows the filling amount (Phr) of the dielectric substance “A” on the horizontal axis, and the tan δ peak value and ta value on the vertical axis.
The peak temperature of nδ is taken. The tan δ value and the tan δ peak temperature both increase with increasing dielectric material loading. About 100-150
At Phr, the tan δ value saturates and shows a value of about 3.5. The peak temperature of tan δ is also around 20 ° C., which is around room temperature.

FIG. 3 shows the temperature on the horizontal axis and the tan δ value of the sample in which the dielectric material “A” was mixed with the polymer material on the vertical axis. This is a comparison of the tan δ values of the samples that have passed through. As shown in this figure, in the sample two weeks after the heat molding, the peak value was about 2.4 immediately after the heat molding, but decreased to about 1.8. Such a decrease in the peak value is because the dielectric substance contained in the molding material gradually grows from the surface to the inside of the molding material, and the crystallization proceeds. Therefore, in order to avoid the progress of the crystallization, a constraining layer made of a silicon material is provided by attaching a silicon resin film or the like. As a result, crystallization from such a surface is avoided, and a decrease in tan δ with time is suppressed.

The product of the present invention described above (samples 1, 2, 4 to 6)
In order to increase the excluded volume and improve the dielectric properties, dioctyl phthalate (DOP) and tricresyl phosphate (TC
A plasticizer such as P) may be added. Then, the mechanical resonance point (Wn) and the electric resonance point (We) can be easily adjusted, and the crystal growth of the dielectric substance “A” is further prevented, so that the deterioration of the damping performance is avoided.

The present invention is not limited to the above-described embodiment at all, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, since the temperatures at which the samples 1 to 6 exhibit the maximum loss coefficients are various, by combining the temperature ranges at which the maximum loss coefficients exhibit different values, the loss coefficient value is increased over a wide temperature range. Can be maintained.

[0035]

According to the high attenuation material of the present invention, the volume ratio of the organic low molecular weight dielectric substance or the ferroelectric substance to the rubber material or elastomer material having polar side chains is 0.3%.
Since it was dispersed in the amorphous state at the above ratio,
The value of the loss coefficient (tan δ) is increased and the amount of energy absorption is large, so that sound absorption characteristics, vibration suppression characteristics, vibration proof characteristics, shock absorption characteristics, and the like are excellent. According to the method for producing a high attenuation material of the present invention, a mixture of a rubber material or an elastomer material having a polar side chain with an organic low-molecular-weight dielectric substance or a ferroelectric substance having undergone a kneading step is heated to 100 to 250 ° C. , The needle-shaped crystals disappear, and a constrained layer of a silicon material is provided on the surface of the material that has undergone the heat-forming step, so that crystal growth is prevented. As a result, the deterioration of the damping performance is avoided and the durability becomes excellent.

[Brief description of the drawings]

FIG. 1 is a diagram showing a temperature-tan δ characteristic of a high attenuation material according to the present invention.

FIG. 2 is a diagram showing a relationship between a dielectric substance filling amount-a loss coefficient peak value and a dielectric substance filling amount-tan δ peak temperature.

FIG. 3 is a diagram showing a change with time of a loss coefficient due to crystal growth.

FIG. 4 is a diagram showing a mechanical model of a polymer material.

Claims (4)

[Claims] 1. A high-damping material comprising an organic low-molecular-weight dielectric substance or a ferroelectric substance dispersed in a rubber material or elastomer material having polar side chains. 2. The method according to claim 1, wherein a volume ratio of the organic low molecular weight dielectric substance or the ferroelectric substance to a rubber material or an elastomer material having a polar side chain is 0.3 or more. The high attenuation material as described. 3. The high attenuation material according to claim 1, wherein the organic low molecular weight dielectric substance or the ferroelectric substance is dispersed in the rubber material or the elastomer material in an amorphous state. . 4. A step of kneading an organic low molecular weight dielectric substance or a ferroelectric substance with a rubber material or an elastomer material having a polar side chain, and subjecting the material having undergone the kneading step to 100 to 250 ° C. A method for producing a high attenuation material, comprising: a step of performing thermoforming at a temperature; and a step of providing a constraining layer of a silicon material on a surface of the material that has undergone the thermoforming step.