JP5893944B2 - Damping material, damping method and damping material control method - Google Patents

Description

  The present invention relates to a vibration damping material, a vibration damping method, and a vibration damping material control method for reducing vibration generated in a building or a road.

  In various fields such as buildings, roads, acoustic equipment, and transportation equipment such as automobiles, damping materials for damping (reducing) vibration are used. The damping material is used to dampen various vibrations depending on the application. In particular, in order to dampen vibrations at a low frequency, it is necessary to select a material having a large weight according to the weight rule. For example, a sheet formed of asphalt, metal, gypsum, or the like having high viscosity and specific gravity is known as a damping material for attenuating vibration at a low frequency. However, workability (handleability) and usage modes are limited in a high-weight vibration damping material such as asphalt. Therefore, although further improvement is desired, it has been difficult to achieve both lightness and vibration damping properties.

  For example, in Japanese Patent Application Laid-Open No. 2011-1692 (Patent Document 1), asphalt is provided on the upper and lower surfaces of a base material using a fiber woven fabric as a base material between a base layer made of an asphalt mixture and a surface layer made of an asphalt mixture. A vibration reduction pavement in which laminated sheets are laid is disclosed. In this document, the fiber-based nonwoven fabric is used to ensure the strength of the sheet due to tensile properties, and examples of the fiber-based woven fabric include synthetic fiber nonwoven fabrics such as polyester fibers and glass fiber nonwoven fabrics, and glass fiber nonwoven fabrics are preferred. Have been described.

  However, the fiber-based nonwoven fabric does not have sufficient vibration damping properties, and particularly has low vibration damping properties for low frequency vibrations. Furthermore, since form retainability is low, handling property is low and uses are limited.

  On the other hand, International Publication WO2007 / 116676 (Patent Document 2) discloses a non-woven fiber structure having a non-woven fiber structure by heat-treating a non-woven fiber assembly containing wet heat adhesive fibers with high-temperature steam, and in the thickness direction. A hard molded body in which wet-heat adhesive fibers are fused with a uniform adhesion rate is manufactured. This document describes that the hard molded body can be used as a building material board.

Japanese Patent Application Laid-Open No. 2010-229809 (Patent Document 3) includes a non-woven fiber structure including a wet heat adhesive fiber and a fiber fixed to the wet heat adhesive fiber by fusing. Further, there is disclosed a sound insulation panel in which the nonwoven fiber structure has a fiber adhesion rate of 3 to 85% and an apparent density of 0.03 to 0.7 g / cm ³ . In this document, the sound insulation panel can achieve excellent sound absorption performance over a wide frequency range, and by adjusting the thickness ratio, density, etc. between the nonwoven fiber structure and the face material, it is 100 to 5000 Hz (especially 250 to It is described that it is effective also for a low frequency band sound of 1500 Hz).

  However, these documents do not describe the vibration and damping performance and the control method thereof.

In International Publication WO2011 / 111608 (Patent Document 4), a buffer formed of a nonwoven fiber structure in which fibers are fixed between a floor base material and a floor finish layer by fusion of wet heat adhesive fibers. In a sound insulation floor structure in which an intermediate layer containing a material is interposed, a sound insulation floor structure in which the cushioning material and a damping material containing asphalt are laminated is disclosed. This document describes that the apparent density of the nonwoven fiber structure can be selected from the range of 0.02 to 0.5 g / cm ³ , and if the density is too small, the sound insulation of floor impact sound is improved. However, while the feeling of walking is reduced and flooring is likely to occur, if the density is too large, the nonwoven fibrous structure is too hard to easily propagate vibration, and the sound insulation of floor impact sound may be reduced. Have been described.

  However, even in this document, a vibration damping material is used for sound insulation of floor impact sound, but the vibration damping property has not been evaluated, and the laminated structure of the non-woven fiber structure and the vibration damping material and the sound insulation property. Is not described, and the relationship between the laminate and the vibration damping property is not described. Furthermore, the density of the non-woven fiber structure is only described as having an appropriate density for sound insulation.

JP 2011-1692 A (Claim 1, paragraph [0036], Example) International Publication No. WO2007 / 116676 (Claims, Examples) JP 2010-229809 A (Claim 1, paragraph [0099]) International Publication WO2011 / 111608 (Claims, paragraphs [0049] to [0051], FIG. 7)

  Accordingly, an object of the present invention is to provide a method capable of easily controlling the damping performance of a lightweight damping material formed of a non-woven fiber structure.

  Another object of the present invention is to provide a method capable of easily controlling the damping performance according to the vibration of the target frequency.

  Still another object of the present invention is to provide a method capable of easily controlling workability and handleability simultaneously with vibration damping.

  Another object of the present invention is to provide a vibration damping material and a vibration damping method capable of achieving both light weight and vibration damping properties.

  Still another object of the present invention is to provide a vibration damping material and a vibration damping method capable of reducing vibration at a low frequency and improving durability even though it is excellent in workability and handleability and is lightweight. There is.

  As a result of intensive studies, the present inventors have found that a non-woven fiber structure in which fibers are fixed by fusion of wet heat adhesive fibers is lightweight, excellent in vibration damping properties, and has a natural frequency. Based on the facts, it was found that the damping performance of the damping material can be easily controlled, and the present invention has been completed.

That is, the vibration damping material control method of the present invention includes a wet heat-adhesive fiber, and the damping property of the vibration damping material formed of a nonwoven fiber structure to which the fiber is fixed by fusion of the wet heat adhesive fiber. In which the natural frequency of the non-woven fiber structure is used as an index to control a frequency range for exhibiting damping properties. In this control method, the natural frequency may be adjusted based on the bulk density. Furthermore, in addition to controlling the damping performance, the spring elasticity of the damping material may also be controlled by adjusting the equivalent spring constant based on the bulk density. In the control method of the present invention, the non-woven fiber structure may have a bulk density of about ³⁰ to 200 kg / m ³ . The equivalent spring constant per unit area of the nonwoven fiber structure may be about 1 × 10 ⁶ to 200 × 10 ⁶ (N / m) / m ² . The control method of the present invention may be a method for attenuating vibrations having a frequency of 500 Hz or less. In the control method of the present invention, the non-woven fiber structure may be plate-shaped or sheet-shaped, and the fiber adhesion rate in the thickness direction may be uniform. An average fineness of the wet heat adhesive fiber may be about 1 to 10 dtex.

  The present invention also includes a vibration damping method that uses a vibration damping material including a wet heat adhesive fiber and is formed of a nonwoven fiber structure to which the fiber is fixed by fusion of the wet heat adhesive fiber. It is. This vibration damping method may be a vibration damping method that attenuates vibrations having a frequency of 500 Hz or less.

  The present invention includes a heat-adhesive fiber, a non-woven fiber structure in which the fiber is fixed by fusion of the wet-heat adhesive fiber, and has a controllable natural frequency based on the bulk density. A vibration material is also included. This damping material may have a natural frequency of about 10 to 500 Hz.

  In the present invention, it is possible to easily control the damping performance of a lightweight damping material formed of a nonwoven fiber structure. In particular, by adjusting the bulk density of the non-woven structure, it is possible not only to easily control the damping performance according to the vibration of the target frequency, but also to control the spring elasticity, and at the same time the damping performance and workability In addition, the handleability can be easily controlled.

  In addition, the vibration damping material formed from a non-woven fibrous structure contains wet heat adhesive fibers, and the fibers are fixed by fusion of the wet heat adhesive fibers. it can. In particular, it is possible to reduce vibration at a low frequency despite being excellent in workability and handleability and being lightweight. Furthermore, durability can also be improved compared with the lightweight damping material formed with the conventional nonwoven fabric and the foaming body.

FIG. 1 is a graph showing acceleration response magnification with respect to vibration frequency in the vibration damping material of the present invention and the conventional nonwoven fabric. FIG. 2 is a graph showing the natural frequency with respect to the bulk density of the damping material having a thickness of 4 mm in the example. FIG. 3 is a graph showing the natural frequency with respect to the bulk density of the damping material having a thickness of 8 mm in the example. FIG. 4 is a graph showing the natural frequency with respect to the bulk density of the damping material having a thickness of 12 mm in the example. FIG. 5 is a graph showing an equivalent spring constant per unit area with respect to the bulk density of a damping material having a thickness of 4 mm in the example. FIG. 6 is a graph showing an equivalent spring constant per unit area with respect to the bulk density of the damping material having a thickness of 8 mm in the example. FIG. 7 is a graph showing an equivalent spring constant per unit area with respect to the bulk density of a damping material having a thickness of 12 mm in the example. FIG. 8 is a graph showing the natural frequency with respect to the average fineness of the damping material in the example. FIG. 9 is a graph showing an equivalent spring constant per unit area with respect to the average fineness of the damping material in the example.

[Damping material]
The vibration damping material of the present invention is formed of a non-woven fiber structure containing wet heat adhesive fibers and having the fibers fixed by fusion of the wet heat adhesive fibers.

In the non-woven fiber structure, the wet heat adhesive fiber is composed of at least a wet heat adhesive resin. The wet heat adhesive resin only needs to be able to flow or easily deform at a temperature that can be easily realized by high-temperature steam and to exhibit an adhesive function. Specifically, a thermoplastic resin that is softened with hot water (for example, about 80 to 120 ° C., particularly about 95 to 100 ° C.) and can be self-adhered or bonded to other fibers, such as an ethylene-vinyl alcohol copolymer. And vinyl alcohol polymers, polylactic acid resins such as polylactic acid, and (meth) acrylic copolymers containing (meth) acrylamide units. Further, it may be an elastomer that can be easily flowed or deformed by high-temperature steam and can be bonded. These wet heat adhesive resins can be used alone or in combination of two or more. Of these, vinyl alcohol polymers containing α-C _2-10 olefin units such as ethylene and propylene, particularly ethylene-vinyl alcohol copolymers are preferred.

  In the ethylene-vinyl alcohol copolymer, the ethylene unit content (copolymerization ratio) is, for example, 5 to 65 mol% (for example, 10 to 65 mol%), preferably 20 to 55 mol%, and more preferably. It is about 30-50 mol%. When the ethylene unit is within this range, a unique property of having wet heat adhesiveness but not hot water solubility is obtained. If the proportion of the ethylene units is too small, the ethylene-vinyl alcohol copolymer easily swells or gels with low-temperature steam (water), and its form is likely to change only once wetted with water. On the other hand, when the ratio of the ethylene unit is too large, the hygroscopicity is lowered, and fiber fusion due to wet heat is difficult to be exhibited, so that it is difficult to ensure practical strength. When the ratio of the ethylene unit is particularly in the range of 30 to 50 mol%, the processability to a shape such as a sheet or a plate is particularly excellent.

  The saponification degree of the vinyl alcohol unit in the ethylene-vinyl alcohol copolymer is, for example, about 90 to 99.99 mol%, preferably 95 to 99.98 mol%, more preferably 96 to 99.97 mol. %. When the saponification degree is too small, the thermal stability is lowered, and the stability is lowered by thermal decomposition or gelation. On the other hand, if the degree of saponification is too large, it is difficult to produce the fiber itself.

  Although the viscosity average degree of polymerization of an ethylene-vinyl alcohol-type copolymer can be selected as needed, it is 200-2500, for example, Preferably it is 300-2000, More preferably, it is about 400-1500. When the degree of polymerization is within this range, the balance between spinnability and wet heat adhesion is excellent.

  The cross-sectional shape (cross-sectional shape perpendicular to the longitudinal direction of the fiber) of wet heat adhesive fibers is limited to general solid cross-sectional shapes such as round cross-sections and irregular cross-sections (flat, elliptical, polygonal, etc.) It may not be a hollow cross section. The wet heat adhesive fiber may be a composite fiber composed of a plurality of resins including at least a wet heat adhesive resin. The composite fiber only needs to have a wet heat adhesive resin on at least a part of the fiber surface, but it is preferable to have a wet heat adhesive resin continuous in the length direction on the fiber surface from the viewpoint of adhesiveness. The coverage of the wet heat adhesive resin is, for example, 50% or more, preferably 80% or more, and more preferably 90% or more.

  Examples of the cross-sectional structure of the composite fiber in which the wet heat adhesive resin occupies the surface include a core-sheath type, a sea-island type, a side-by-side type, a multi-layer bonding type, a radial bonding type, and a random composite type. Among these cross-sectional structures, a core-sheath structure in which the wet heat adhesive resin covers the entire surface of the fiber (that is, the sheath portion is made of the wet heat adhesive resin because it is a structure with high adhesiveness. A core-sheath structure) is preferred. The core-sheath structure may be a fiber in which a wet heat adhesive resin is coated on the surface of a fiber composed of another fiber-forming polymer.

  In the case of a composite fiber, wet heat adhesive resins may be combined with each other, but may be combined with non-wet heat adhesive resins. Non-wet heat adhesive resins include water-insoluble or hydrophobic resins such as polyolefin resins, (meth) acrylic resins, vinyl chloride resins, styrene resins, polyester resins, polyamide resins, polycarbonate resins, Examples include polyurethane resins and thermoplastic elastomers. These non-wet heat adhesive resins can be used alone or in combination of two or more.

  Among these non-wet heat adhesive resins, from the viewpoint of heat resistance and dimensional stability, resins having a melting point higher than that of wet heat adhesive resins (particularly ethylene-vinyl alcohol copolymers), such as polypropylene resins and polyester resins. Resins and polyamide resins, particularly polyester resins and polyamide resins are preferred from the standpoint of excellent balance between heat resistance and fiber-forming properties.

  In the case of a composite fiber composed of a wet heat adhesive resin and a non-wet heat adhesive resin (fiber-forming polymer), the ratio (mass ratio) of both can be selected according to the structure (for example, core-sheath structure). The wet heat adhesive resin is not particularly limited as long as it exists on the surface. For example, wet heat adhesive resin / non-wet heat adhesive resin = 90/10 to 10/90, preferably 80/20 to 15/85, more preferably It is about 60/40 to 20/80. If the proportion of wet heat adhesive resin is too large, it will be difficult to ensure the strength of the fiber, and if the proportion of wet heat adhesive resin is too small, it will be difficult to have the wet heat adhesive resin continuously in the length direction of the fiber surface. Thus, the wet heat adhesiveness is lowered. This tendency is the same when the wet heat adhesive resin is coated on the surface of the non-wet heat adhesive fiber.

  The average fineness of the wet heat adhesive fibers can be selected, for example, from the range of about 0.01 to 100 dtex, for example, 0.1 to 50 dtex, preferably 1 to 10 dtex, more preferably 2 to 5 dtex (particularly 2.5 to 4 dtex). When the average fineness is within this range, the balance between vibration damping properties and mechanical properties is excellent.

  The average fiber length of the wet heat adhesive fibers can be selected from a range of, for example, about 10 to 100 mm, preferably 20 to 80 mm, and more preferably about 25 to 75 mm. When the average fiber length is within this range, the fibers are sufficiently entangled, so that the mechanical strength of the fiber structure is improved.

  The crimp rate of the wet heat adhesive fiber is, for example, 1 to 50%, preferably 3 to 40%, and more preferably about 5 to 30%. The number of crimps is, for example, about 1 to 100 pieces / 25 mm, preferably about 5 to 50 pieces / 25 mm, and more preferably about 10 to 30 pieces / 25 mm.

  The nonwoven fiber structure may further contain non-wet heat adhesive fibers in addition to the wet heat adhesive fibers. Examples of non-wet heat adhesive fibers include cellulosic fibers (for example, rayon fiber, acetate fiber, etc.) in addition to fibers made of the non-wet heat adhesive resin constituting the composite fiber. These non-wet heat adhesive fibers can be used alone or in combination of two or more. These non-wet heat adhesive fibers can be selected according to the target properties, and when combined with semi-synthetic fibers such as rayon, a fiber structure having relatively high density and high mechanical properties can be obtained. The average fineness and average fiber length of the non-wet heat adhesive fibers can be selected from the same range as the wet heat adhesive fibers.

  The ratio (mass ratio) between the wet heat adhesive fiber and the non-wet heat bond fiber is determined according to the type and use of the damping material. The wet heat bond fiber / non-wet heat bond fiber = 100/0 to 20/80 (for example, 99/1 to 20/80), preferably 100/0 to 50/50 (for example, 95/5 to 50/50), more preferably about 100/0 to 70/30. When the ratio of wet heat adhesive fibers is too small, the hardness decreases and it becomes difficult to maintain the handleability as a fiber structure.

  The non-woven fiber structure including the wet heat adhesive fiber has a fiber adhesion rate of 3 to 85% (for example, 5 to 60%) by fusion of the wet heat adhesive fiber. It is 5 to 50% (for example, 6 to 40%), more preferably 6 to 35% (particularly 8 to 30%). In this invention, since the fiber is adhere | attached in such a range, the freedom degree of each fiber is high and can express high damping property. Furthermore, in order to improve strength, the fiber adhesion rate may be, for example, about 10 to 85%, preferably 20 to 80%, and more preferably about 30 to 75%.

  Although the fiber adhesion rate in this invention can be measured by the method as described in the Example mentioned later, the ratio of the cross section number of the fiber which adhered 2 or more with respect to the cross section number of all the fibers in a non-woven fiber cross section is shown. Therefore, a low fiber adhesion rate means that a ratio of a plurality of fibers fused to each other (a ratio of fibers fused by fusing) is small.

  In the present invention, the fibers constituting the non-woven fiber structure are bonded at the contact points of the respective fibers. In order to express a large bending stress with as few contacts as possible, this bonding point is the thickness direction. It is preferable that the fiber structure is uniformly distributed from the surface of the fiber structure to the inside (center) and back. When the adhesion points are concentrated on the surface or inside, not only is it difficult to ensure excellent vibration damping properties, mechanical properties, and moldability, but also the form stability in a portion where the adhesion points are small.

  Therefore, in the cross section in the thickness direction of the fiber structure, it is preferable that the fiber adhesion rate in each of the regions divided in three in the thickness direction is in the above range. Furthermore, the ratio of the minimum value to the maximum value of the fiber adhesion rate in each region (minimum value / maximum value) (the ratio of the minimum region to the region with the maximum fiber adhesion rate) is, for example, 50% or more (for example, 50 to 100%), preferably 55 to 99%, more preferably 60 to 98% (especially 70 to 97%). In the present invention, since the fiber adhesion rate has such uniformity in the thickness direction, it is excellent in hardness, bending strength, folding resistance and toughness even though the bonded area of the fiber is small. , Workability, handling and durability can be improved. Furthermore, since the bonding area of the fibers is small, there are many fibers that can vibrate freely and have excellent vibration absorbability. Therefore, the transmitted vibration is damped by the non-woven fiber structure. That is, the nonwoven fiber structure in the present invention has both the mechanical properties as a board and the vibration damping properties as a fiber structure.

  The non-woven fiber structure has an appropriate hardness and can improve workability and handleability. Therefore, the non-woven fiber structure conforms to the A-type durometer hardness test (JIS K6253 “Testing the hardness of vulcanized rubber and thermoplastic rubber”). The hardness according to a conforming test) is, for example, A40 or more, preferably A45 or more (for example, 45 to 80), and more preferably A50 or more (for example, 50 to 75).

  The nonwoven fabric structure has a maximum bending stress in at least one direction (preferably in all directions) of 0.05 MPa or more (for example, 0.05 to 100 MPa), preferably 0.1 to 30 MPa, more preferably 0. It may be about 2 to 20 MPa. If the maximum bending stress is too small, it will easily break due to its own weight or slight load when used for damping materials such as buildings and roads. On the other hand, if the maximum bending stress is too high, it becomes too hard and is easily broken and broken.

The basis weight of the nonwoven fiber structure can be selected, for example, from a range of about 50 to 10,000 g / m ² , preferably 100 to 5000 g / m ² , more preferably 200 to 3000 g / m ² (particularly 300 to 2000 g / m ^2). ) If the basis weight is too small, it is difficult to ensure the hardness. If the basis weight is too large, the web is too thick and high-temperature steam cannot sufficiently enter the inside of the web in wet heat processing, and the structure is uniform in the thickness direction. It becomes difficult to make a body.

  Nonwoven fiber structures (or fibers) can be further added with conventional additives such as stabilizers (heat stabilizers such as copper compounds, UV absorbers, light stabilizers, antioxidants, etc.), dispersants, thickeners. Agents, fine particles, colorants, antistatic agents, flame retardants, plasticizers, crystallization rate retarders, lubricants, antibacterial agents, insect and acaricides, antifungal agents, matting agents, heat storage agents, fragrances, fluorescent whitening agents And may contain a wetting agent and the like. These additives can be used alone or in combination of two or more. These additives may be carried on the structure surface or may be contained in the fiber.

  The non-woven fiber structure containing wet heat adhesive fibers is about 70 to 150 ° C. (especially 80 to 120 ° C.) with respect to a web (for example, semi-random web, parallel web, etc.) obtained using staple fibers. Is obtained by a method of injecting high-temperature water vapor at a pressure of about 0.1 to 2 MPa (particularly preferably 0.2 to 1.5 MPa). For details of the production method, see International Publication No. WO2007 / 116676 and International Publication. The production method described in WO2009 / 28564 can be used.

  The obtained non-woven fiber structure is usually obtained as a plate-like or sheet-like molded body, and is subjected to cutting or punching processing depending on the type of the damping material. Secondary molding may be performed by molding. Examples of thermoforming include compression molding, pressure forming (extrusion pressure forming, hot plate pressure forming, vacuum pressure forming, etc.), free blow molding, vacuum forming, bending, matched mold forming, hot plate forming, wet heat press forming, etc. Is available.

  In addition, when fixing a vibration damping material composed of a nonwoven fiber structure to another member (such as another vibration damping material) using an adhesive or a pressure-sensitive adhesive, the adhesive or pressure-sensitive adhesive is a non-woven fiber structure. Therefore, the adhesive or pressure-sensitive adhesive can be prevented from penetrating by laminating a sheet material such as a film or non-woven fabric on the surface and / or back surface of the non-woven fiber structure. May be.

  When the non-woven fiber structure is in the form of a sheet or plate, the average thickness of the damping material can be appropriately selected depending on the application, but is, for example, 1 to 100 mm, preferably 3 to 50 mm, more preferably 3 to 30 mm. (Especially 5 to 10 mm).

  The non-woven fiber structure may be combined with other vibration damping materials. For example, when the non-woven fiber structure is in the form of a sheet or plate, a laminate with other vibration damping layers, for example, asphalt, etc. It may be a laminate with a damping layer containing a bituminous material, a metal such as iron, and a weight material such as gypsum. By combining the non-woven fiber structure with a damping layer containing these heavy materials, the lightness of the damping material containing the heavy materials can be improved.

[Vibration control method]
In the control method of the present invention for controlling the damping performance of the damping material formed of the nonwoven fabric structure, the damping performance is controlled even though the damping material has a nonwoven fabric structure. It is possible to do. Although the natural frequency of a substance is known as a characteristic related to vibration damping properties, knowledge about the natural frequency related to a vibration damping material having a fiber structure such as a nonwoven fabric has not been known. Therefore, as a result of measuring the natural frequency of the vibration damping material having a fiber structure, the present inventors have found that the above-mentioned non-resonance material formed of a nonwoven fabric does not have the natural frequency. It was found that the damping material formed of the woven fiber structure has a natural frequency.

FIG. 1 is a graph showing acceleration response magnification with respect to vibration frequency in the vibration damping material of the present invention and the conventional nonwoven fabric. Specifically, FIG. 1 is a result of measuring the acceleration response magnification of damping materials 1 to 4 created in examples described later, and damping materials 1 to 3 are formed of the nonwoven fiber structure of the present invention. The bulk density is damping material 1:50 kg / m ³ , damping material 2: 100 kg / m ³ , damping material 3: 150 kg / m ³ , respectively. On the other hand, the damping material 4 is a needle punched nonwoven fabric (bulk density 100 kg / m ³ ) formed of a conventional polyester fiber.

  In this specification, the method for measuring the acceleration response magnification is as described in the embodiments described later in detail. However, a sheet-like damping material is placed on the shaking table, and a plate is further placed thereon. After the weights are stacked, the vibration table is forcibly vibrated vertically to impart vibration to the vibration damping material, and the vibration transmitted from the vibration damping material to the plate weight is measured as an acceleration response magnification. The measured acceleration response magnification represents the damping performance of the damping material. When the acceleration response magnification is 1, it indicates that the vibration is transmitted as it is to the plate weight. On the other hand, when the acceleration response magnification exceeds 1, it indicates that the vibration is amplified and transmitted by the plate weight. Conversely, when the acceleration response magnification is less than 1, the vibration is attenuated by the plate weight. Indicates that it was transmitted. That is, the vibration damping material can attenuate the vibration at a frequency of less than 1 in the acceleration response magnification. Furthermore, in the graph of the acceleration magnification with respect to the frequency, the peak indicates the natural frequency.

  As is clear from FIG. 1, the damping materials 1 to 3 of the present invention all have a peak, that is, a natural frequency, whereas the conventional damping material 4 has a peak (natural frequency). Not. Further, as is apparent from FIG. 1, the natural frequency in the damping material of the present invention has a correlation with the bulk density, and as the bulk density increases, the natural frequency of the nonwoven fibrous structure also increases. Have a relationship. Furthermore, in the damping materials 1 to 3 of the present invention, the acceleration response magnification is less than 1 at a frequency about 50 to 150 Hz higher than the natural frequency, and the damping property is exhibited. Therefore, the damping material of the present invention can control the damping performance of the damping material based on the natural frequency (for example, using the natural frequency as an index, depending on the intended frequency for each application). In particular, it is possible to control the damping performance of the damping material by adjusting the bulk density and controlling the natural frequency using the relationship that the natural frequency increases as the bulk density increases. .

  Furthermore, as is clear from FIG. 1, compared with the conventional damping material 4, the damping materials 1 to 3 of the present invention show damping properties even for vibrations having a low frequency of 500 Hz or less. ing. For this reason, it is possible to dampen vibrations at a low frequency without using a heavy damping material such as asphalt.

  The natural frequency of the damping material (nonwoven fiber structure) can be selected from a range of, for example, about 10 to 10000 Hz, and may be, for example, about 20 to 5000 Hz, preferably about 30 to 1000 Hz. Since the damping material is effective for vibrations at a low frequency, it may be, for example, about 10 to 500 Hz, preferably 20 to 300 Hz, more preferably about 30 to 200 Hz (particularly 40 to 150 Hz). In the present invention, the natural frequency is selected from these ranges in accordance with the target vibration (vibration subject to vibration suppression). For example, the frequency exceeds about 50 to 150 Hz higher than the natural frequency. It is possible to adjust a damping material that exhibits damping properties with respect to the frequency of the region.

The bulk density (apparent density) ρ of the damping material (non-woven fiber structure) can be selected from a range of about 20 to 500 kg / m ³ , and is particularly preferably in a range effective for vibration at a low frequency, for example, 200 kg. / M ³ or less (for example, 30 to 200 kg / m ³ ), preferably 40 to 180 kg / m ³ , more preferably 50 to 160 kg / m ³ (particularly 50 to 120 kg / m ³ ).

Moreover, the bulk density also affects the spring elasticity, and when the bulk density increases, the equivalent spring constant tends to increase. Therefore, in applications that require workability and handleability, the bulk density ρ is, for example, 100 to 300 kg / m ³ , preferably 120 to 120, because it retains a certain degree of spring elasticity and is excellent in vibration damping properties. 250 kg / ^{m 3,} more preferably 130~200kg / ^{m 3} may be a (especially 140~180kg / ^{m 3)} about. Furthermore, the bulk density ρ is, for example, 50 to 120 kg / m ³ , preferably 60 to 100 kg / m ³ , and more preferably 70 to 90 kg from the viewpoint of achieving both vibration damping properties and workability with respect to low frequency vibrations. It may be about / m ³ .

In the present invention, an equivalent spring constant k ′ per unit area can be used as an index for evaluating spring elasticity. The equivalent spring constant per unit area of the damping material (non-woven fiber structure) is 1 × 10 ⁻⁶ (N / m) / m ² or more (for example, 1 × 10 ⁶ to 200 × 10 ⁶ (N / m ) / M ² ) and can be selected according to the application. In particular, the elastic characteristics of the damping material can be controlled by adjusting the bulk density and controlling the equivalent spring constant within these ranges by utilizing the relationship that the equivalent spring constant increases as the bulk density increases.

Specifically, in applications that are excellent in form stability and require workability and handleability, the equivalent spring constant k ′ is, for example, 5 × 10 ⁶ (N / m) / m ² or more, preferably 10 ×. It may be about 10 ^{6 to} 150 × 10 ⁶ (N / m) / m ² , more preferably about 15 × 10 ^{6 to} 120 × 10 ⁶ (N / m) / m ² . In particular, in applications where both vibration damping performance and workability for low frequency vibrations are compatible, the equivalent spring constant k ′ is, for example, 5 × 10 ⁶ to 80 × 10 ⁶ (N / m) / m ² , preferably May be about 10 × 10 ⁶ to 50 × 10 ⁶ (N / m) / m ² , more preferably about 15 × 10 ⁶ to 40 × 10 ⁶ (N / m) / m ² .

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Each physical property value in the examples was measured by the following method. In the examples, “parts” and “%” are based on mass unless otherwise specified.

(1) Weight per unit area (g / m ² )
Measured according to JIS L1913 “Testing method for general short fiber nonwoven fabric”.

(2) Thickness h (mm), bulk density ρ (g / cm ³ )
The thickness h was measured according to JISL 1913 “Testing method for general short fiber nonwoven fabric”, and the bulk density (apparent density) ρ was calculated from this value and the basis weight value.

(3) Fiber adhesion rate Using a scanning electron microscope (SEM), a photograph was taken in which the cross section of the plate-like substrate of the laminate was magnified 100 times. The photograph of the cross-section in the thickness direction of the photographed plate-like base material is divided into three equal parts in the thickness direction. The ratio of the number of cut surfaces where the fibers are bonded to each other was determined. Of the total number of fiber cross sections that can be found in each region, the ratio of the number of cross sections in a state where two or more fibers are bonded is expressed as a percentage based on the following formula. In addition, in the part which fibers contact, there exists a part which is simply contacting, without melt | fusion, and a part which has adhere | attached by melt | fusion. However, by cutting the laminate for microscopic photography, the fibers in contact with each other are separated from each other by the stress of each fiber on the cut surface of the plate-like substrate. Therefore, in the cross-sectional photograph, it can be determined that the contacting fibers are bonded to each other.

Fiber adhesion rate (%) = (number of cross sections of fibers bonded two or more) / (total number of cross sections of fibers) × 100
However, for each photograph, all the fibers with visible cross sections were counted, and when the number of fiber cross sections was 100 or less, a photograph to be observed was added so that the total fiber cross section number exceeded 100. In addition, the fiber adhesion rate was calculated | required about each area | region divided into three equally, and the ratio (minimum value / maximum value) of the minimum value with respect to the maximum value was also calculated | required as uniformity in the thickness direction.

(4) Natural frequency f _n
A sheet-shaped vibration damping material was placed on a vibration table ("i220 / SA2" manufactured by IMV Co., Ltd.), and a plate weight (stainless steel plate 3 mm thickness, 25 kg / m ² ) was further laminated thereon. Later, the vibration table is forced to vibrate vertically to impart vibration to the damping material, and the vibration transmitted from the damping material to the plate weight is accelerated by an accelerometer (Model No. 4507 manufactured by Brüel & Kjær). Measured as a magnification. At this time, the acceleration response magnification when the frequency was changed from 0 Hz to 500 Hz was represented by a graph.

(5) Equivalent spring constant k ′ per unit area
It calculated according to the following formula from the measurement result of the natural frequency f.

k ′ = (2πf) ² × m
(Where f represents the natural frequency and m represents the weight of the weight).

Example 1 (Example of manufacturing damping material 1)
As a wet heat adhesive fiber, a core-sheath type composite staple fiber having a core component of polyethylene terephthalate and a sheath component of ethylene-vinyl alcohol copolymer (ethylene content 44 mol%, saponification degree 98.4 mol%) ) Prepared by Kuraray, “Sophista”, fiber thickness (average fineness) 3.3 dtex, fiber length 51 mm, core-sheath mass ratio = 50/50, number of crimps 21 / inch, crimp rate 13.5% did.

Using this core-sheath type composite staple fiber, a card web having a basis weight of about 100 g / m ² was prepared by a card method, and three webs were stacked to form a card web having a total basis weight of about 300 g / m ² .

  The card web was transferred to a belt conveyor equipped with a 50 mesh, 500 mm wide stainless steel endless net. In addition, the belt conveyor which has the same metal mesh is equipped in the upper part of the metal mesh of this belt conveyor, and it rotated in the same direction at the same speed, respectively, and used the belt conveyor which can adjust the space | interval of these metal meshes arbitrarily. .

  Next, the steam web is introduced into the steam spraying device provided in the lower conveyor, and steam treatment is performed by ejecting high-temperature steam of 0.2 MPa from the device so as to pass in the thickness direction of the card web (perpendicularly). As a result, a molded body having a non-woven fiber structure was obtained. In this steam spraying device, a nozzle is installed in the lower conveyor so as to spray high-temperature steam toward the web via a conveyor net, and a suction device is installed in the upper conveyor. Further, another jetting device, which is a combination of the arrangement of the nozzle and the suction device reversed, is installed on the downstream side in the web traveling direction of the jetting device, and steam treatment is performed on both the front and back sides of the web. did.

  In addition, the hole diameter of the water vapor | steam injection nozzle was 0.3 mm, and the vapor | steam injection apparatus with which the nozzle was arranged in 1 row at 1 mm pitch along the width direction of the conveyor was used. The processing speed was 3 m / min, and the interval (distance) between the upper and lower conveyor belts on the nozzle side and the suction side was adjusted so that a structure having a thickness of 8 mm was obtained. The nozzles were arranged on the back side of the conveyor belt so as to be almost in contact with the belt.

The obtained non-woven fiber structure had a board-like form and was very hard as compared with a general nonwoven fabric. The bulk density was 50 kg / m ³ , and the fiber adhesion rate was 14.4% on the front side, 12.1% on the center, and 10.7% on the back side. This nonwoven fiber structure was cut into a 30 mm square (length 30 mm × width 30 mm) and used as the damping material 1.

Example 2 (Example of manufacturing damping material 2)
In Example 1, a non-woven fibrous structure having a thickness of 8 mm was manufactured by using a card web having a total number of webs of about 800 g / m ² and adjusting the interval between the upper and lower conveyor belts. . The bulk density was 100 kg / m ³ , and the fiber adhesion rate was 30.3% on the front side, 28.5% at the center, and 29.2% on the back side. This nonwoven fiber structure was cut into a 30 mm square and used as the vibration damping material 2.

Example 3 (Production example of damping material 3)
In Example 1, a non-woven fibrous structure having a thickness of 8 mm was manufactured by using a card web having a total number of webs of about 1200 g / m ² and adjusting the distance between the upper and lower conveyor belts. . The bulk density was 150 kg / m ³ , and the fiber adhesion rate was 62.4% on the front surface side, 58.8% on the central portion, and 62.0% on the back surface side. This nonwoven fiber structure was cut into a 30 mm square and used as the damping material 3.

Comparative Example 1
A needle punched nonwoven fabric (regular polyester fiber, fiber thickness (average fineness) 6.0 dtex, fiber length 51 mm, no binder type) having a thickness of 6 mm, a bulk density of 100 kg / m ³ , and a 30 mm square was used as the damping material 4.

[Measurement of the natural frequency _{f n]}
The results of measuring the natural frequency f _n of Examples 1-3 and Comparative Example 1 damping material 1-4 obtained in shown in Fig.

As described above, from the results of FIG. 1, the damping member 1-3 of Example Whereas has a natural frequency f _n, damping material 4 of the comparative example does not have a natural frequency.

[Effect of bulk density ρ of natural frequency f _n ]
In order to adjust the thickness h of the damping materials 1 to 3, a damping material having a thickness of 4 mm was prepared by adjusting the number of laminated webs and the interval between the upper and lower conveyor belts. Further, FIG. 2 shows the result of measuring the natural frequency f _n by cutting each damping material into a size b of 20 mm square, 30 mm square, and 40 mm square, respectively.

Furthermore, the damping material 1 to 3, 20 mm square, respectively, 30 mm square, was cut into 40mm square, shown in FIG. 3 the results of measuring the natural frequency _{f n.}

Furthermore, about the damping materials 1-3, the damping material of thickness 12mm was prepared by adjusting the lamination | stacking number of webs, and the space | interval between an upper and lower conveyor belt. Furthermore, for each damping material, 20 mm square, respectively, 30 mm square, was cut into 40mm square, Figure 4 shows the results of measuring the natural frequency _{f n.}

2 to 4, the natural frequency f _n was proportional to the bulk density ρ regardless of the difference in the thickness h and the size b. Therefore, the natural frequency f _n can be controlled according to the application by adjusting the bulk density ρ.

[Effect of bulk density ρ on equivalent spring constant k ′ per unit area]
In order to adjust the thickness h of the damping materials 1 to 3, a damping material having a thickness of 4 mm was prepared by adjusting the number of laminated webs and the interval between the upper and lower conveyor belts. Further, FIG. 5 shows the results of measuring the equivalent spring constant k ′ per unit area by cutting each damping material into a size b of 20 mm square, 30 mm square, and 40 mm square, respectively.

  Further, FIG. 6 shows the results of measuring the equivalent spring constant k ′ per unit area by cutting the damping materials 1 to 3 into 20 mm square, 30 mm square, and 40 mm square, respectively.

  Furthermore, about the damping materials 1-3, the damping material of thickness 12mm was prepared by adjusting the lamination | stacking number of webs, and the space | interval between an upper and lower conveyor belt. Further, FIG. 7 shows the result of measuring the equivalent spring constant k ′ per unit area by cutting each damping material into 20 mm square, 30 mm square, and 40 mm square.

  From the results of FIGS. 5 to 7, the equivalent spring constant k ′ was substantially proportional to the bulk density ρ regardless of the difference in thickness h and size b. Therefore, the equivalent spring constant k ′ can be controlled according to the application by adjusting the bulk density ρ.

[Effect of Fiber Thickness (Average Fineness) T of Natural Frequency f _n ]
For the damping materials 1 to 3, damping materials were prepared using wet heat adhesive fibers having fiber diameters of 1.7 dtex and 5.0 dtex while changing the fiber thickness (average fineness) T, respectively. Further, FIG. 8 shows the result of measuring the natural frequency f _n by cutting each damping material into a size b of 20 mm square, 30 mm square, and 40 mm square, respectively.

  From the results of FIG. 8, the damping material with an average fineness of 5.0 dtex has the lowest natural frequency.

[Effect of fiber thickness T on equivalent spring constant k 'per unit area]
For the damping materials 1 to 3, damping materials were prepared using wet heat adhesive fibers having fiber diameters of 1.7 dtex and 5.0 dtex while changing the fiber thickness (average fineness) T, respectively. Further, FIG. 9 shows the results of measuring the equivalent spring constant k ′ per unit area by cutting each damping material into a size b of 20 mm square, 30 mm square, and 40 mm square, respectively.

  From the result of FIG. 9, the damping material having an average fineness of 3.3 dtex showed the highest equivalent spring constant.

  The vibration damping material of the present invention can be used as a vibration damping material for attenuating (reducing) vibrations in various fields such as buildings, roads, acoustic equipment, and transportation equipment such as automobiles. It can be used for automobile interior materials, aircraft inner wall materials, building materials, furniture, etc., because it can be adjusted with ease and mechanical properties.

Claims (12)

  A method for controlling vibration damping properties of a vibration damping material formed of a nonwoven fiber structure including a wet heat adhesive fiber and fixed by fusion of the wet heat adhesive fiber, the nonwoven fiber structure A method of controlling the frequency range for exhibiting damping properties using the natural frequency of the body as an index.   The control method according to claim 1, wherein the natural frequency is adjusted based on the bulk density.   The control method according to claim 1 or 2, wherein, in addition to controlling the damping performance, the spring elasticity of the damping material is also controlled by adjusting an equivalent spring constant based on the bulk density. The control method according to claim 1, wherein the non-woven fiber structure has a bulk density of 30 to 200 kg / m ³ . The control method according to claim 1, wherein an equivalent spring constant per unit area of the nonwoven fiber structure is 1 × 10 ⁶ to 200 × 10 ⁶ (N / m) / m ² .   The control method according to claim 1, which is a method for attenuating vibrations having a frequency of 500 Hz or less.   The control method according to any one of claims 1 to 6, wherein the non-woven fiber structure is plate-shaped or sheet-shaped, and the fiber adhesion rate in the thickness direction is uniform.   The control method according to claim 1, wherein the wet heat adhesive fiber has an average fineness of 1 to 10 dtex. Using a damping material that includes a wet heat adhesive fiber, is formed of a nonwoven fiber structure in which the fiber is fixed by fusion of the wet heat adhesive fiber , and has a natural frequency that can be controlled based on bulk density A damping method that damps vibrations.   The vibration damping method according to claim 9, wherein vibrations having a frequency of 500 Hz or less are attenuated.   A damping material that includes a wet heat adhesive fiber, is formed of a nonwoven fiber structure to which the fiber is fixed by fusion of the wet heat adhesive fiber, and has a natural frequency that can be controlled based on bulk density.   The vibration damping material according to claim 11, wherein the natural frequency is 10 to 500 Hz.

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