WO2008023852A1

WO2008023852A1 - Damping member and method for producing the same

Info

Publication number: WO2008023852A1
Application number: PCT/JP2007/067084
Authority: WO
Inventors: Masaaki Takagi; Keisuke Nakamura; Masamichi Komatuzaki
Original assignee: Yukigaya Kagaku Kogyo Kabushiki Kaisha
Priority date: 2006-08-25
Filing date: 2007-08-27
Publication date: 2008-02-28
Also published as: CN101506541A; CN101506541B; JPWO2008023852A1

Abstract

Disclosed is a damping member which is excellent in vibration damping property and durability such as heat resistance, light resistance and hydrolysis resistance. Also disclosed is a method for producing such a damping member. Specifically disclosed is a damping member made of a polyurethane resin which is composed of a polyisocyanate compound and a polycarbonate polyol compound. This damping member may be particularly used for a speaker edge or a sound absorbing material within an engine cover.

Description

Specification

Title of invention

Damping material and its manufacturing method

Technical field

The present invention relates to a vibration damping material and a method for producing the same, and particularly to a vibration damping material and a polyurethane resin foam having a carbonate bond and a foam made of a polyurethane resin having a carbonate bond. It relates to the manufacturing method. Background art

Conventionally, ether-based polyurethane resins having an ether bond in the molecular structure and ester-based polyurethane resins having an ester bond in the molecular structure are known, and these forms are used as vibration damping materials.

In addition, as a damping material for foam made of polyurethane resin, as a cushioning material, anti-vibration material, vibration damping material, sound absorbing material, and coupling member, it can be attached to, or brought into close contact with, various vibration suppression materials. Installed, connected, combined, etc. to prevent installation and unnecessary vibration. It is also installed in a space to absorb unnecessary and unpleasant vibrations.

These are used for building materials, various electrical equipment, prime movers, electric motors, home appliances, audio equipment, vehicles, sound absorbing materials in engine covers, speaker edges, and so on.

As these conventional examples, Japanese Patent Laid-Open No. 2 0 0 3-2 8 6 3 2 5, Japanese Patent Application Laid-Open No. 7-6 2 0 5 1, Japanese Patent Application Laid-Open No. And those described in Japanese Patent No. 3 0 0 6 4 1 8.

However, these conventional damping materials made of polyurethane resin cannot be said to have sufficient damping performance, and a material with a large damping effect is required in a smaller amount.

Also, the durability is not sufficient. If it is made of ether-based polyurethane resin, it will deteriorate due to heat and ultraviolet rays. As a result, it deteriorates during use outdoors or in high-temperature environments and cannot be used. Another problem is that it turns yellow when used with gases such as N O X, known as gas yellowing.

In addition, if it is made of ester-based polyurethane resin, such durability is relatively good, but it is hydrolyzable and decomposes under high humidity conditions and cannot be used at all. This hydrolyzability is a phenomenon in which a polymer is degraded by water, and it deteriorates in contact with water, in a humid or high humidity environment. It appears as a decrease in strength, discoloration, and a decrease in volume. It can even collapse if it is severely degraded.

The speaker edge described above is a member that connects the diaphragm and the frame in speakers used in various audio equipment, etc., and attenuates unnecessary vibration of the diaphragm while supporting the diaphragm. is there. Speaker edges are required to be lightweight, high-strength, highly vibration-damping and free from reverse resonance. Some ether-based polyurethane resins are used for this speaker edge application, but the sound quality of the speaker is not sufficient. This is because the damping characteristics are not sufficient, the output deviation due to reverse resonance in the midrange is large, and the frequency characteristics do not become flat. On the other hand, ester polyurethane resins have relatively little output deviation due to reverse resonance, good vibration damping, and good sound quality, but they have the above-mentioned hydrolysis and are used for a long time even in general indoor environments. Is not possible and not practical. For this reason, it has been proposed to use a mixture of an ester polyurethane resin and an ether polyurethane resin. However, if sufficient hydrolysis resistance is desired, the ether polyurethane resin will occupy most of the sound quality. In particular, it will be the characteristics of an ether polyurethane resin.

The present invention eliminates such conventional drawbacks, and is a polyurethane foam and vibration damping material having excellent vibration damping properties and excellent durability such as yellowing resistance, heat resistance, light resistance, hydrolysis, etc. And it aims at providing the manufacturing method. Disclosure of the invention

As a result of examining various polyurethane resins, the present invention has found that a polyurethane resin having a carbonate bond in the molecule has an excellent durability, and further, as a result of intensive research, it is light in weight, high in strength and has a high loss factor. It came to complete this invention excellent as a vibrating material. That is, the present invention is a vibration damping material characterized by comprising a polyurethane resin having a carbonate bond.

The invention of claim 2 is characterized in that in the vibration damping material of the invention of claim 1, the polyurethane resin has a foam structure. The invention of claim 3 is characterized in that the vibration damping material of claim 1 has a foam structure in which polyurethane resin is compressed. The invention of claim 4 is characterized in that in the vibration damping material of the invention of claim 1, the polyurethane resin has a foam structure that is heat-compressed. In the invention of claim 5, the damping material of the invention of claim 1, 2, 3 or 4 In the above, the loss coefficient of the polyurethane resin is 0.1 or more and 0.7 or less. The invention of claim 6 is characterized in that the damping material of claims 1 to 5 is a speaker edge material. Further, the invention of claim 7 is the method for producing a vibration damping material of claim 4, wherein the polyurethane resin is heat compression molded.

According to each invention, it is possible to provide a vibration damping material with excellent vibration damping properties, hydrolysis resistance, light deterioration resistance, and gas discoloration properties. It became possible. In addition, stable performance can be maintained over a long period of time, which has a significant effect on maintaining the performance of the built-in equipment. In addition, according to the manufacturing method of the invention of claim 7, it is possible to obtain such an excellent vibration damping material and a foam with good workability of the material. In particular, according to the invention of claim 6, it is possible to provide a speaker having high sound quality and durability.

Brief Description of Drawings

FIG. 1 is a graph showing the output characteristics of a speaker when the material of Example 4 of the present invention is used for a speaker edge.

FIG. 2 is a graph showing the output characteristics of the speaker when the material of Comparative Example 1 is used for the speaker edge.

Fig. 3 is a graph showing the output characteristics of the speaker when the material of Comparative Example 2 is used for the speaker edge. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below.

In the present invention, the polyurethane resin is a reaction product of a polyol compound and a polyisocyanate compound, and is a resin having a urethane bond in the molecule. The polyurethane resin having a carbonate bond of the present invention is a resin having a carbonate bond (-0-0-C0-0-) in addition to a urethane bond in the molecule of the polyurethane resin.

The carbonate bond in the molecule of the polyurethane resin having a carbonate bond can be produced by using a polyol compound having a carbonate bond in the molecule of the polyol compound used as a raw material of the resin.

The polyol compound is a compound having an average of at least two hydroxyl groups in one molecule, such as a polymer diol compound having two hydroxyl groups in the molecule and a polymer triol compound having three hydroxyl groups. In the present invention, the polyol compound includes poly -Use the Bonate polyol compound. As the polymer polyol compound, in addition to the polycarbonate polyol compound, a polyether polyol compound and / or a polyester polyol compound can be used in combination. Furthermore, various additives described later are added and used as a polyol composition.

Examples of the polycarbonate small polyol compound include a polycarbonate diol compound having two hydroxyl groups in one molecule, a polycarbonate triol compound having three or more hydroxyl groups in one molecule, and a polycarbonate tetraol compound. It is done. A polycarbonate polyol compound is formed by polymerizing from a monomer at a carbonate bond. A diol compound can be used as the monomer. As a method for producing a carbonate bond using a diol compound, for example, it can be synthesized by transesterifying a diol compound and a carbonate ester compound. ·

As the monomer for forming the polycarbonate polyol compound, various diols can be used, aliphatic diols having aliphatic hydrocarbons as the skeleton can be used, and aliphatic diols having branched hydrocarbons as the skeleton can be preferably used. The aliphatic diol having a branched hydrocarbon as a skeleton can impart a branched hydrocarbon structure to the polycarbonate polyol compound to be produced, and can reduce the viscosity of the polycarbonate polyol compound. As a result, stable production can be achieved by foam molding described later.

Examples of such a monomer include aliphatic diols having 4 or more carbon atoms. A preferred monomer is an aliphatic diol having 5 to 16 carbon atoms, and more preferred is an aliphatic diol having 6 to 12 carbon atoms. Examples of these diols include: methyl-1,4 monopentanediol, methyl-1,5-pentanediol, methyl 1,6 monohexanediol, methyl-1,7 heptanediol, methylol 1, Examples include 8-octanediol, methyl-1,9-nanonediol, methyl-1,10-decanediol, and methyl-1,11-undecanediol. In addition, a linear aliphatic diol can be used in combination, and the resulting polycarbonate polyol has a branched portion and a non-branched portion, which can increase the loss factor of the resulting polyurethane resin. I can do it.

The average molecular weight of the polycarbonate polyol compound is preferably 5 0 0 to 5 0 0 0, If the polycarbonate polyol compound is in these ranges, a urethane resin having excellent vibration damping properties can be obtained, and a liquid polyol compound can be obtained. The average number of hydroxyl groups in the polycarbonate polyol compound is 2 or more per molecule, preferably 2 or more and 4 or less. Particularly preferably, it is 2 or more and 3 or less. These can be used alone or in combination of several kinds.

A preferred combination in the case of using a combination of polycarbonate polyol compounds having different numbers of hydroxyl groups is a combination of a diol compound having two hydroxyl groups and a triol compound having three hydroxyl groups. In this combination, the weight ratio of diol compound: triol compound is from 10:90 to 50:50, more preferably from 15:85 to 40:60. Combining within this range will improve the vibration damping performance. When the triol compound exceeds 90, the resulting resin loses flexibility and the loss factor becomes small, resulting in poor vibration damping. When the triol compound is less than 50, the loss coefficient increases, but the strength decreases and the mechanical strength is insufficient. If this is outside the above range, the use of each product is limited.

In the present invention, a polyether polyol compound can be used as the polymer polyol compound in addition to the polycarbonate polyol compound.

Polyether polyol compounds can be used within the range that does not impair vibration damping, hydrolyzability, heat resistance, yellowing and light resistance, and within 100 parts by weight of polymer polyol compound More preferably, it is within 80 parts by weight, more preferably within 60 parts by weight. There is no particular lower limit to the use of the polyether polyol compound.

When using a polyether polyol compound in combination with a polymer polyol compound having a different number of hydroxyl groups, the weight ratio of the diol compound having two hydroxyl groups and the triol compound having three hydroxyl groups is diol compound: triol. The compound is preferably 10:90 force to 50:50, more preferably 15:85 force to 30:70. Combining within this range will improve the vibration damping performance.

The vibration damping material comprising the polyurethane resin of the present invention can be produced using a foaming agent, a catalyst, and a foam stabilizer in addition to the polyisocyanate compound and the polymer polyol compound.

The blowing agent generates a gas that becomes the pores of the foam. As the foaming agent, water, hydrocarbon, halogenated alkane, halogenated methane or a mixture thereof is preferable. Water Advantageously, it is used in an amount of 0.5 to 10, preferably 1 to 5 parts per 100 parts by weight of the polyol compound. Hydrocarbons and halogenated alkanes are advantageously used in amounts of 5 to 75 parts per 100 parts by weight of the polyol compound. In particular, water is preferable because it can produce a foam having an open cell structure, can have a higher loss factor than a foam having a closed cell structure, and does not swell or tear when thermoforming described later.

The catalyst promotes the reaction between the polyol compound and the isocyanate compound. As the catalyst, known metal catalysts and amine catalysts used for the production of polyurethane foam are used. As the metal catalyst, a tin compound, a zinc compound, an aluminum compound, a titanium compound and the like are preferable. Amine-based catalysts include tertiary amines, diazabicycloalkenes and salts thereof, and these can be used in combination. Specific examples of the catalyst include dibutyltin laurate, dibutyl-rutin laurate, triethylamine, dimethylcyclohexylamine and the like. The catalyst is preferably used in the range of 0.01 to 3 parts by weight of catalyst with respect to 100 parts by weight of the polyol compound. The foam stabilizer adjusts the size, continuity and independence of the foam in the foam produced. As the foam stabilizer, known ones used for the production of polyurethane foams can be used. Examples thereof include polydimethylsiloxane-polyalkyleneoxide block polymer and vinylsilane-polyalkylene polyol polymer.

The polyol composition containing the polycarbonate polyol compound is preferably in a liquid state, and the polymer polyol composition in which various auxiliary agents described below are mixed has a foam molding temperature. It is liquid at C to 60 ° C, more preferably at 25 ° C to 50 ° C, and even more preferably at 30 ° C to 45 ° C. This is suitable for the foaming method described later.

The vibration damping material of the present invention can be produced by adding various additives. As additives, plasticizers, colorants, pigments, fillers, antioxidants, ultraviolet absorbers, and the like can be used. These can be added to and mixed with the polyisocyanate compound and the polyol composition, respectively.

The polyisocyanate compound in this invention has an average of at least two isocyanate groups per molecule. The polyisocyanate compound is an aromatic polyisocyanate compound in which an isocyanate group is bonded to a carbon atom of an aromatic hydrocarbon compound, or an aliphatic polyisocyanate bonded to a carbon atom of an aliphatic hydrocarbon compound. Nate compounds can be used. Examples of preferred aromatic polyisocyanate compounds include

2, 4_ or 2, 6-toluene diisocyanate, diphenylmethane diisocyanate (hereinafter abbreviated as “MDI”), p-phenylene diisocyanate, polymethylene poly (polyethylenepolyiso) Cyanate (hereinafter abbreviated as “polymeric MDI”), and mixtures thereof. In addition, M D I and M D I prepolymers or quasi-prepolymer derivatives thereof can also be used.

Aliphatic polyisocyanate compounds include hydrogenated derivatives of aromatic isocyanates, hexane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and cyclohexane diisocyanate. .

The polyisocyanate compound can be a polymerized polyisocyanate compound, a polymerized diisocyanate compound, a polymerized triisocyanate having an average of at least three isocyanate groups per molecule. A compound etc. can be used.

The polyisocyanate compound is 0.7 to 5 equivalents, preferably 0.8 to 1.5 equivalents, more preferably 0.9 to 5 to 1 equivalent to 1 equivalent of active hydrogen groups in the polymer polyol compound. 2. React at a rate of 2 equivalents. In addition, when water is used for the foaming agent described later, the ratio of the isocyanate group of the polyisocyanate compound is 0.7 to 5 equivalents, preferably 0.8 to 1.5 equivalents with respect to 1 equivalent of the active hydrogen group of water. Increase the amount to use.

The polyurethane foam used in the vibration damping material of the present invention is a polyol composition in which a polymer polyol compound is mixed with a foaming agent, a catalyst, and a foam stabilizer, and this polyol composition is mixed with a polyisocyanate compound. At the same time, gas is generated and foamed. For mixing, the polyisocyanate compound and the polyol composition are 20 ° C to 60 ° C, more preferably 25 ° C to 50 ° C, and even more preferably 30 ° C to 45 ° C. It is preferable to mix at ° C. If the temperature is high, the reaction is fast and stable production cannot be achieved, and if the temperature is low, the liquid has a high viscosity and it is difficult to mix uniformly, and a foam with a uniform cell structure cannot be produced.

Mixing is preferably performed uniformly, and uniform bubbles can be obtained. Mixing is preferably performed in as short a time as possible, and it is within 30 seconds, preferably within 10 seconds, more preferably within 5 seconds, from mixing the two liquids to casting. A method in which two liquids of a polyisocyanate compound and a polyol composition are continuously supplied to a mixing chamber, mixed and discharged is preferable. As such a method, there is a stirring and mixing method, and a mixing chamber equipped with a stirring blade rotating at high speed can be used. It is preferable to rotate the stirring blade at a high speed from the viewpoint of quick and uniform mixing, preferably 2 00 0 r or more, more preferably 3 0 0 0 rp ni or more, more preferably 5 0 00 rpm or more. is there.

Another more preferable method is high-pressure collision mixing. High-pressure collision mixing is a method in which two liquids are supplied at high pressure and collided at high speed in a mixing chamber in a high-pressure mixer. By mixing by this method, a highly viscous liquid can be mixed, and the selection of materials that can be used is expanded. In addition, uniform mixing can be achieved in a short time, and a foam having a uniform cell structure can be obtained.

By producing in this way, the foam of the present invention can have an apparent specific gravity of 0. Ol gZ cm ^{3 to} 0.3 g Z cm ³ . Also, the tensile strength can be 2 N / cm ² to 30 ONZ cm ² . Thereby, the tensile strength per apparent weight can be set to 2550 to 10 ° 0NZcm ² / g, and more preferably 450 to 600 cm ² Zg. As a result, a lightweight and high-strength damping material can be manufactured. Even with a high loss factor, the mechanical strength becomes insufficient when the tensile strength per apparent weight is less than 25 ON / cm ² / g. Speaker edges are not preferable because the diaphragm cannot be supported at the center of the speaker.

Since the vibration damping material of the present invention is manufactured from a polyisocyanate compound and a polycarbonate polyol compound, the hydrolysis resistance is good, and the strength retention after the hydrolysis test can be made 70% or more. More preferably, it can be 80% or more. In the hydrolysis test, an environmental test is performed in which the sample is left suspended in an environmental test chamber maintained at a temperature of 70 ° C and humidity of 90% for 8 weeks, and the tensile strength before and after the environmental test is measured to calculate the retention rate. To do.

The urethane foam of the vibration damping material of the present invention can be used after being thermoformed. Thermoforming is a molding method in which polyurethane foam is compressed and molded in a heated mold, and the foam can be made dense or a curved surface can be molded. If possible, it is advantageous in terms of thermal energy to form at low temperature if possible, and can be formed in a short time. The damping material urethane foam of the present invention has a molding temperature of 220 ° C. or lower, more preferably 20 ° C. or lower. The lower limit is not limited, but it is 1700C or higher.

The damping material thus molded can have an apparent specific gravity of 0.2 to 1. Og / ctn ³ . As a result, the damping material can be molded in three dimensions, the shape of the required damping material can be designed freely, and used for applications such as speaker wedges that efficiently absorb vibrations in complex shapes. Can do.

Since the vibration damping material of the present invention is configured as described above, it has excellent vibration damping properties. Although the damping performance varies depending on the frequency to be damped, the damping material of the present invention has excellent damping performance from 10 Hz to 1 MHz, particularly from 2 O Hz to 10 O KHz. Damping performance can be estimated by a loss factor (tan S value by dynamic viscoelasticity measuring device of JIS K 6 3 94), and the damping factor of this invention has a loss factor of 0.1 It becomes 0.7 and vibration damping is good. Furthermore, the present invention aims at a vibration control effect of an audible sound, and the loss coefficient at room temperature in the frequency band of 100 Hz to 100 Hz is 0.1 to 0.7, more preferably 0. It can be set from 2 to 0.5 and is excellent in sound quality when used as a speaker edge.

The speaker edge material of the present invention can achieve a larger loss factor at a lighter weight than the conventional speaker edge material, and at the same time has a high mechanical strength. A speaker using one edge of such a speaker has good sound quality. This is because the unnecessary vibration of the diaphragm of the speaker is effectively damped and the linearity is improved due to its light weight. In addition, because the mechanical strength is sufficient, it is possible to make it lighter. C In addition, the output is flat in the frequency band of 100 Hz to 100 Hz, which is important for hearing. can do.

Example

In Example 1, the following two solutions were prepared.

A liquid

Polyisocyanate

TDI 40 parts by weight

Liquid B (Polymer polyol composition)

Polymer polyol

Polycarbonate diol 10 parts by weight

Polycarbonate triol 90 parts by weight

Foaming agent (water)

Silicone foam stabilizer

Catalyst 0. 1 part by weight of colorant

The polymer polyol, foaming agent, foam stabilizer, and catalyst were mixed to make B liquid.

A liquid and B liquid are set to 40 ° C, respectively, and the flow ratio of A liquid: B liquid is 4: 10 in a continuous mixer with rotating stirring blades rotating at 500 rpm. And mixed and stirred. Then, after mixing, it was poured into a mold and foamed to obtain a polyurethane foam. The obtained polyurethane foam had a specific gravity of 0.1, was soft and rubbery. When this foam was compressed to a thickness of 1/5 with a hot plate at a constant temperature, it was molded at a hot plate temperature of 190 ° C or higher. At this time, the thermoforming temperature was 190 ° C.

Examples 2 to 8 were as follows.

A polyol diol and a polycarbonate triol of the polyol composition of the liquid B were prepared in the same manner as in Example 1 with the mixing ratio shown in Table 1.

Comparative Example 1 was as follows.

The polycarbonate diol and polycarbonate triol in the above examples were replaced with polyether triol to obtain 100 parts by weight of polyether polyol. Mixing and stirring, casting, and molding were performed in the same manner as in Example 1 above.

The obtained polyurethane foam had a specific gravity of 0.1, was soft and rubbery.

Comparative Example 2 was as follows.

The polycarbonate diol and the polycarbonate triol in the above examples were replaced with polyester polyol to obtain 100 parts by weight of polyester polyol. Mixing, stirring, casting and molding were performed in the same manner as in Example 1 above.

The vibration damping materials of the above examples and comparative examples were tested for thermoformability, strength, damping properties (loss factor), and durability (hydrolyzability, light accelerated degradation test). The results are shown in Table 1.

table 1

The polyurethane foam prepared in the above example was cut to a thickness of 8 nun and the thickness was 0.

A single edge of a speaker with an S-shaped cross section was created by thermoforming it into a ring shape of 9 mm and an outer diameter of 18 O mni. A cone-type speaker with a diameter of 18 cm and an impedance of 6 Ω was created with this speaker edge. This speaker was mounted in a JIS C 5 3 2 standard sealed box, driven by an amplifier, and its sound quality was evaluated and confirmed as follows. The results are shown in Table 1 above.

A clean sound quality like listening to the original sound ◎

Sound quality that is as good as listening to the original sound, but with a slightly thin sound

Thin and poor sound quality, partially exaggerated sound quality △

The output frequency characteristics of this speaker were measured according to JIS C 5 5 3 2. As a result, in Example 4, as shown in FIG. 1, from 100 Hz to L 0 00 Hz, the output sound pressure deviation was within 4 dB, and there was no sharp valley and no reverse resonance. In Comparative Example 1, as shown in FIG. 2, there are peaks and valleys with an output deviation of 12.5 dB from 300 Hz to 700 Hz, and reverse resonance occurs. In Comparative Example 2, as shown in FIG. 3, there are peaks and valleys with an output deviation of 9 dB from 300 Hz to 700 Hz, and reverse resonance occurs. The speaker using the damping material of the present invention has excellent sound quality that faithfully reproduces the original sound because the output is flat in the frequency range of 100 Hz to 100 Hz, which characterizes the sound quality. It is a speaker and is particularly suitable for a mid-low range speaker.

In Examples 1 to 8, the damping coefficient is 0.1 or more and the damping performance is good.

In addition, the strength maintenance rate is high for durability such as UV light inferiority and hydrolyzability.

Of these, Example 7 uses a large amount of diol and is excellent in vibration damping properties, but is too flexible and inferior in strength, so its usage is limited. In Example 8, the use of triol is 100, which is hard and lacks flexibility, and its usage is limited.

On the other hand, both of Comparative Examples 1 and 2 have good vibration damping properties but poor durability.

Thermoformability

Each foam was cut into a thickness of 10 mm and compressed with a hot plate heated to a constant temperature so that the thickness became 1 Z 5 (2 mm) for 60 seconds to obtain the lowest temperature at which thermoforming was possible. The results are shown in Table 1. The vibration damping urethane foam of the present invention can be thermoformed at a lower temperature than conventional urethane foam and has excellent thermoformability.

Measuring method The measuring method used in this invention is as follows.

Thermoformability: Thermoformability was tested using the same sample as the hydrolyzability test. Each foam was cut into a thickness of 10 mm and compressed with a hot plate for 60 seconds so that the thickness became 1 Z5, and the lowest temperature at which thermoforming was possible was determined.

Specific gravity: Apparent specific gravity calculated by cutting out a rectangular parallelepiped and calculating the weight and length of each side.

Tensile strength, elongation: J I S K 6 2 5 1 Breaking strength of dumbbell-shaped type 1.

Tensile strength per apparent weight Determined by the following equation.

(Formula) Tensile strength per apparent weight = Tensile strength (N / ctti ² ) / Apparent specific gravity (g / _C m ³ ) Light accelerated degradation test: JISK 7 3 5 0-2 Irradiation test with xenon lamp.

A T L A S Company SUNT E S T X L S + Irradiation for 1 0 0 0 hours. The retention of tensile strength before and after irradiation was obtained from the following formula. In addition, the loss factor after the test was measured.

(Formula) Retention rate = (Tensile strength after test) / (Tensile strength before test)

Hydrolyzability: Each foam was cut to 5 mm thickness and suspended in an environmental test room at 70 ° C. 90% RH for 8 weeks. The tensile strength was measured before and after this environmental test, and the retention rate was determined by the above formula.

Loss coefficient: tan S value by dynamic viscoelasticity measuring device of JISK 6 3 9 4 In Examples and Comparative Examples, the foam was thermoformed with a hot plate so as to have a thickness of 1/5 (2 mm). Frequency 1 ΚΗζ. Temperature 25 ° C.

Industrial applicability

The damping material of the present invention is a buffer material, vibration preventing material, vibration attenuating material, sound absorbing material, or bonding material, which is attached to, closely attached to, connected to, or connected to various members to suppress vibration. For example, it can be used to suppress unnecessary and unpleasant vibrations. It is also installed in a space to absorb unnecessary and unpleasant vibrations. It can be used for building materials, various electrical equipment, prime movers, electric motors, home appliances, acoustic equipment, vehicles, sound absorbing materials in engine covers, and a single edge.

Claims

The scope of the claims

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