JP2004082421A - Vibration-damping sheet and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration-damping sheet, thin, lightweight and easily handled, which solves the problems of the conventional technologies by foaming an acrylic emulsion, coating a nonwoven fabric with the acrylic emulsion and laminating the porous resin layer on the nonwoven fabric. <P>SOLUTION: This method for manufacturing a vibration-damping sheet, in which a porous resin layer consisting of the acrylic emulsion and having open cells is laminated on the nonwoven fabric, is characterized by practicing a foaming process of the acrylic emulsion with a foaming ratio of 3-10 times and impregnating and coating processes of the acrylic emulsion to the nonwoven fabric and thereby laminating the nonwoven fabrics with the porous resin layer having the open cells. <P>COPYRIGHT: (C)2004,JPO

Description

【００３５】
実施例１，２は、ｔａｎδの値も大きく、ｔａｎδが０．６以上の温度領域も約４０℃広く良好な制振特性を有していることを示している。一方、比較例１，２は、ｔａｎδも低く、温度領域も無く制振性能は不十分である。
【００３６】
【発明の効果】
本発明の制振シートは、発泡したアクリル樹脂を用いたもので、軽量で優れた制振性、衝撃吸収性を発揮することができ、また連続気泡のため吸音効果もあり、かつ容易に加工でき、取り扱い、施工の簡便性も確保できる。
【図面の簡単な説明】
【図１】本発明の実施態様に係わるアクリルフォーム制振材の断面図である。
【図２】本発明のアクリルフォーム制振材の電子顕微鏡断面図である。
【符号の説明】
１　アクリルフォーム
２　不織布
３　アクリルフォーム含浸層
４　アクリルフォーム制振シート[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is used for reducing vibrations and noises generated in houses, condominiums, residential buildings such as office buildings, automobiles, railway vehicles, various vehicles such as ships, home appliances, OA devices, and the like, and The present invention relates to a vibration damping sheet that is lightweight and easy to handle.
[0002]
[Prior art]
Floors and sinks of houses, condominiums, office buildings, etc., and home appliances, such as components mounted near refrigerator compressors and washing machine motors, use damping materials to maintain quietness. Have been. This vibration damping material is required to be mounted on a portion where vibration is generated, to control the generated vibration, or not to transmit the vibration to the surroundings. Therefore, it is required that the vibration can be effectively controlled according to the frequency of the generated vibration.
As these damping materials, those containing asphalt or rubber and high specific gravity aggregate have been generally proposed. However, since these conventional damping materials are heavy, they are processed at the time of use such as handling and cutting. Was very poor. In addition, since there was no cushioning property, the shock absorption was poor.
There is known a vibration damping and soundproofing material formed by laminating a nonwoven fabric, a soundproofing layer, and an open-cell foam layer (Japanese Patent Application Laid-Open No. 8-323907). The soundproof layer is composed of a high specific gravity filler and a binder component containing unvulcanized rubber as a main component, and the open-cell foam layer is composed of a flexible polyurethane foam.
BACKGROUND ART A vibration damping sound insulating sheet obtained by adding a gas to an aqueous slurry composed of an emulsion of a synthetic resin such as an acrylic resin or a rubber component and a high specific gravity filler and then applying the gas to a synthetic fiber nonwoven fabric is known ( JP-A-11-105158). However, since the gas contained in the aqueous slurry is for stabilizing the compressibility and cutability of the vibration damping and sound insulating sheet, the content is small, and the bubbles in the vibration damping sound insulating sheet are closed cells. .
[0003]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems of the prior art by foaming and coating an acrylic emulsion on a nonwoven fabric and laminating the porous resin layer on the nonwoven fabric, thereby providing a thin, lightweight, and easy-to-handle vibration damping sheet. is there.
[0004]
[Means for Solving the Problems]
The first invention relates to a vibration damping sheet comprising an acrylic emulsion and a porous resin layer having open cells laminated on a nonwoven fabric.
[0005]
The second invention relates to the vibration damping sheet according to the first invention, which has an expansion ratio of 3 to 10 times.
[0006]
The third invention relates to the vibration damping sheet according to the first invention or the second invention, wherein the thickness of the impregnated layer is at least 0.2 mm.
[0007]
According to a fourth aspect of the present invention, a porous resin layer having open cells is laminated on a nonwoven fabric by performing a foaming step of an acrylic emulsion having an expansion ratio of 3 to 10 times and an impregnation and application step of the acrylic emulsion on the nonwoven fabric. The present invention relates to a method for producing a vibration damping sheet.
[0008]
The fifth invention relates to a method for producing a vibration-damping sheet according to the fourth invention, wherein the foamed acrylic emulsion is impregnated and applied to a nonwoven fabric, and then dried at 60 to 160 ° C.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Acrylic emulsion The acrylic emulsion used in the present invention is obtained by emulsion polymerization of a monomer mixture containing an acrylic monomer as a main monomer.
Preferred acrylic monomers include acrylic acid, methacrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Having an alkyl group having 1 to 22 carbon atoms, such as cyclohexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, and perfluoroalkyl (meth) acrylate There are methacrylate, acrylamide, hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate.
[0010]
Other monomers can be copolymerized within a range that does not impair the performance of the acrylic polymer. Other monomers include, for example, unsaturated monobasic acids such as ethylene, crotonic acid, vinyl acetic acid, acryloxypropionic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, cyclohexanedicarboxylic acid, and the like. Unsaturated dibasic acid, unsaturated anhydride such as maleic anhydride, tetrahydrophthalic anhydride, vinyl propionate, styrene, butadiene, isoprene, allylsulfonic acid, styrenesulfonic acid, vinylsulfonic acid, allylphosphonic acid, vinyl Examples include phosphonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and vinyl acetate.
[0011]
Among the above-mentioned monomers, the following monomers have no carboxyl group but are hydrophilic monomers (monomers having a solubility in water at 20 ° C. of more than 2% by weight).
That is, methyl acrylate, (meth) acrylamide, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, allylsulfonic acid, styrenesulfonic acid, vinylsulfonic acid, allylphosphonic acid, vinylphosphonic acid, 2-acrylamide -2-methylpropanesulfonic acid and vinyl acetate.
[0012]
Emulsion polymerization can be performed by a known method. For example, a method in which the monomer is charged in an aqueous medium and polymerized, a method in which the monomer is continuously or intermittently dropped and polymerized in an aqueous medium, or a method in which water is added to the monomer and the monomer is added. For example, a method of preparing an emulsion and continuously or intermittently dropping it into an aqueous medium to carry out polymerization may be mentioned.
[0013]
The emulsifier used in the emulsion polymerization may be a commonly used emulsifier, for example, sodium alkyl benzene sulfonate, sodium alkyl sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl sulfate, sodium dialkyl sulfosuccinate, naphthalene sulfone Examples include anionic surfactants such as an acid formalin condensate and nonionic surfactants such as polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyethylene glycol fatty acid ester and sorbitan fatty acid ester.
[0014]
In the emulsion polymerization, a known polymerization initiator can be used, and there is no particular limitation on the method of adding the polymerization initiator, and a method of adding the polymerization initiator at a time at the start of the polymerization, a method of sequentially adding the polymerization initiator, and a method of starting the polymerization with the monomer mixture A method in which the agent is dissolved and added dropwise can be used. Further, two or more of these methods may be used in combination.
[0015]
As the polymerization initiator, any of a water-soluble polymerization initiator and an oil-soluble polymerization initiator can be used. For example, organic peroxides such as benzoyl peroxide, tert-butyl peroxide and dicumyl peroxide; azo compounds such as azobisisobutyronitrile, azobis (2-methylbutyronitrile), and azobiscyanovaleric acid; Inorganic peroxides such as sodium sulfate, potassium persulfate, and ammonium persulfate; and redox-based polymerization initiators comprising these peroxides and reducing agents such as sulfites, ascorbic acid, and erythorbic acid salts.
[0016]
If necessary, various mercaptans, α-methylstyrene, alkyl halides and the like can be used as a chain transfer agent.
[0017]
Since a foam having excellent durability can be formed by the reaction between the carboxyl group in the acrylic emulsion and the cross-linking agent, it is desirable to add a cross-linking agent having reactivity with the carboxyl group in the emulsion polymerization.
Preferred crosslinking agents include those obtained by solubilizing oxides of polyvalent metals such as zinc and calcium with an alkali (eg, aqueous ammonia, ammonium bicarbonate, ammonium carbonate, etc.). The preferred amount of the crosslinking agent is such that the ion equivalent of the polyvalent metal is 10 to 90% based on the carboxyl groups in the acrylic emulsion. If the ion equivalent of the polyvalent metal is less than 10%, the durability is reduced, while if it exceeds 90%, the storage stability of the acrylic emulsion may be reduced.
The preferred glass transition temperature of the emulsion is from -10 to 40C. If the glass transition temperature is too low, the surface of the vibration damping sheet becomes sticky at room temperature, and if the glass transition temperature is too high, the flexibility of the vibration damping sheet surface may be impaired at room temperature.
[0018]
The emulsion used in the present invention includes components generally used in addition to the aqueous resin dispersion, such as an oil, a humectant, an ultraviolet absorber, a chelating agent, and a pH adjuster, as long as the effects of the present invention are not impaired. , A preservative, a thickener, a dye, a pigment, a fragrance and the like can be appropriately compounded.
[0019]
Preferred pigments include organic pigments such as R-221, R-226, B-404 and Y-401; and inorganic pigments such as titanium dioxide, brown iron oxide, red iron oxide, mica titanium and bismuth oxychloride.
[0020]
Examples of the pigment dispersant include anionic surfactants such as sodium polyoxyethylene alkylphenyl ether phosphate, cationic surfactants such as stearyltrimethylammonium chloride, amphoteric surfactants such as sodium β-laurylaminopropionate, and monodispersants. There are nonionic surfactants such as ethylene glycol stearate.
[0021]
Further, as a thickener, an organic thickener such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyethylene oxide, methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, cationized guar gum, cationized cellulose, and an inorganic bentonite type Thickeners, thickeners such as montmorillonite, sounite, hydrite, hectorite and saponite, and hydrated oxides such as boehmite can be used.
[0022]
The emulsion in the present invention needs to be foamed so as to have open cells. Preferred azo compounds are azodicarbonamide (ADCA), azobisisobutyronitonyl (AIBN), and barium azodicarboxylate (Ba / AC), N, N'-dinitrosopentamethylene terolamine (DPT) as a nitroso compound, 4,4'-oxybis (benzenesulfonyl hydrazide) (OBSH), hydrazodicarbonamide (HDCA), and carbazide compound as a hydrazine derivative , Azide compounds, terolazole compounds, bicarbonates, carbonates and the like.
Further, various surfactants may be used as a foaming agent or a foaming assistant. Examples thereof include anionic surfactants such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and sodium alkyldiphenyletherdisulfonate, and polyoxyethylene alkyl esters.
Examples of foaming agents added for the purpose of stabilizing bubbles include ammonium sterate, alkylsulfosuccinate, and quaternary alkylammonium chloride.
[0023]
The preferred expansion ratio is 3 to 10 times. If the expansion ratio is small, it is difficult to form continuous cells, and the bubbles are deformed, whereby the ability to absorb vibration energy is reduced and the shock absorption is deteriorated. On the other hand, when the expansion ratio is too large, the foam is easily broken, and the strength of the bubbles is reduced. In addition, since these bubbles are continuous bubbles, they are also effective in sound absorption.
[0024]
-Nonwoven fabric The nonwoven fabric in the present invention is a substrate on which the above-mentioned acrylic emulsion is impregnated and applied, and is preferably made of synthetic fibers.
Preferred synthetic fibers include polyester, polyethylene, nylon and polypropylene.
Preferred nonwoven fabric manufacturing methods include spunbonding, spunlace, meltblowing, carding, flash spinning, tow opening, and burst fiber methods.
Preferred areal weight of the nonwoven fabric ^{is 30g / m 2 ~300g / m 2} .
[0025]
-Damping sheet The damping sheet of the present invention is formed by laminating a porous resin layer made of the above-mentioned acrylic emulsion and having open cells on a nonwoven fabric.
An aggregate can be contained in the vibration damping sheet of the present invention. The aggregate is not particularly limited, but usually inorganic fine powder such as calcium carbonate, talc, mica, barium sulfate, clay, diatomaceous earth, gypsum, slag, glass powder, and microballoons are used. These aggregates can be used as a mixture of two or more.
A preferable ratio of the aggregate is 2 to 15 parts per 100 parts by mass of the solid content of the acrylic emulsion.
[0026]
The vibration damping sheet of the present invention can be manufactured, for example, as follows. First, an acrylic emulsion, a foaming agent, a crosslinking agent, and, if necessary, an aggregate are mixed, and foamed by a mixer or the like. The preferred expansion ratio is 3 to 10 times. Then, the foamed acrylic emulsion mixture is uniformly impregnated and applied to the nonwoven fabric. At this time, the nonwoven fabric is impregnated with the acrylic emulsion to form an impregnated layer. This sheet is placed in a dryer and dried at 60 to 160 ° C. to obtain a vibration damping sheet having open cells. When the drying temperature is lower than 60 ° C, cross-linking hardly proceeds, and when it is higher than 160 ° C, organic substances may be decomposed.
Preferred impregnation and the coating amount of the emulsion is 200~1500g / ^{m 2.}
[0027]
【Example】
Hereinafter, the present invention will be described with reference to Examples and Comparative Examples of the present invention. The evaluation of the vibration damping sheet was performed according to the following method.
[0028]
Evaluation of Damping Sheet The tan δ of the damping sheet was measured at a frequency of 1 Hz using a viscoelasticity measuring machine (Toyo Seiki Seisakusho; Rheograph). Here, tan δ was calculated from the longitudinal elastic modulus (E ′, E ″). The tan δ was evaluated based on the magnitude of tan δ and the width of the temperature range where tan δ was 0.8 or more.
[0029]
Reference example of acrylic emulsion << Reference example 1 >>
(1) 4.5 parts by mass of acrylonitrile (hereinafter abbreviated as part), 65 parts of ethyl acrylate, 10 parts of methyl methacrylate, 15.5 parts of butyl acrylate, 3.5 parts of acrylamide and 1.5 parts of itaconic acid Then, 0.2 parts of sodium dodecylbenzenesulfonate as an emulsifier for polymerization and 20 parts of deionized water were mixed to prepare a monomer mixture.
(2) 45 parts of deionized water and 15 parts of the monomer mixture prepared in (1) were added to a flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen inlet tube, and the mixture was heated to 60 ° C. under a nitrogen atmosphere. Then, 0.5 part of a 10% aqueous solution of ammonium persulfate and then 0.5 part of a 10% aqueous solution of Rongalite (trade name: formaldehyde sodium sulfoxylate dihydrate) were added, and then the mixture was added in (1) above. The remaining 120 parts of the prepared monomer mixture was added dropwise over 3 hours. At the same time, 5 parts of a 2% aqueous solution of ammonium persulfate was dropped in another system over 3 hours. Thereafter, the reaction was continued at the same temperature for another 2 hours to complete the polymerization. At the end of the polymerization, 8 parts of deionized water and 2 parts of a 25% aqueous solution of ammonia were added, and an acrylic emulsion having a solid concentration of about 55% was added. Got. The glass transition point of the polymer in the acrylic emulsion was -2 ° C.
[0030]
Example 1
For 100 parts of the acrylic emulsion of Reference Example 1 (solid content concentration: 50%), 40 parts of a blowing agent (NOPCO DC-100A manufactured by San Nopco), 2 parts of a zinc crosslinking agent, and a dispersant (T-40 manufactured by Toagosei) Was mixed with 15 parts of a resin microballoon as an aggregate, and the mixture was adjusted to a foaming ratio of 5 times with a mixer. This foamed acrylic emulsion was applied to a nonwoven fabric, and dried with a dryer at 100 ° C. to form a sheet. The coating amount was 400 g / m ² as an acrylic resin. A cross section of the obtained acrylic foam damping sheet by an electron microscope is shown in FIG. 1, and the evaluation results are shown in Table 1. When water was allowed to flow on the acrylic foam damping sheet, the water passed through the sheet. Acrylic foam The cells of the acrylic foam damping sheet were open cells.
[0031]
Example 2
A vibration damping sheet was produced in the same manner as in Example 1. The amount of the acrylic foam resin impregnated was 800 g / m ² . Table 1 shows the evaluation results of the obtained acrylic foam damping sheets.
[0032]
Comparative Example 1
As a comparative example, a vibration damping sheet was produced under the same method and conditions as in Example 1. However, the expansion ratio was 1.5 times. Table 1 shows the evaluation results of the obtained acrylic foam damping sheets.
[0033]
Comparative Example 2
An acrylic foam sheet formed from an acrylic foam and a nonwoven fabric were adhered with an adhesive to produce an acrylic foam vibration-damping sheet having no impregnated layer. The amount of the acrylic resin was 400 g / m ² . Table 1 shows the evaluation results of the obtained acrylic foam damping sheets.
[0034]
[Table 1]

[0035]
Examples 1 and 2 show that the value of tan δ is large and that the temperature range where tan δ is 0.6 or more is about 40 ° C. wider and has good vibration damping characteristics. On the other hand, in Comparative Examples 1 and 2, tan δ was low, there was no temperature range, and the vibration damping performance was insufficient.
[0036]
【The invention's effect】
The vibration damping sheet of the present invention is made of foamed acrylic resin, is lightweight, can exhibit excellent vibration damping properties and shock absorption properties, and has a sound absorbing effect due to open cells, and is easily processed. Simplicity of handling and construction can be ensured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an acrylic foam damping material according to an embodiment of the present invention.
FIG. 2 is an electron microscope sectional view of the acrylic foam damping material of the present invention.
[Explanation of symbols]
1 Acrylic foam 2 Non-woven fabric 3 Acrylic foam impregnated layer 4 Acrylic foam damping sheet

Claims (5)

A vibration damping sheet in which a porous resin layer made of an acrylic emulsion and having open cells is laminated on a nonwoven fabric. The vibration damping sheet according to claim 1, wherein the expansion ratio is 3 to 10 times. The damping sheet according to claim 1 or 2, wherein the thickness of the impregnated layer is at least 0.2 mm. A porous resin layer having open cells is laminated on a nonwoven fabric by performing a foaming step of an acrylic emulsion having an expansion ratio of 3 to 10 times and an impregnation and application step of the acrylic emulsion on the nonwoven fabric. Sheet manufacturing method. The method for producing a vibration damping sheet according to claim 4, wherein the foamed acrylic emulsion is impregnated and applied to the nonwoven fabric, and then dried at 60 to 160C.

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