KR20140047209A - Fiber aggregate having excellent sound absorption performance and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a fiber aggregate with improved sound absorption performance and a manufacturing method thereof, and more specifically, to a fiber aggregate with improved sound absorption performance, wherein the fiber aggregate improves sound absorption performance even though the thickness of a sound absorbing material is reduced, and improves sound absorption rates in a low frequency band of 1000Hz or less. Moreover, the present invention relates to a fiber aggregate with improved sound absorption performance and a manufacturing method thereof, wherein the fiber aggregate prevents the degradation of sound absorption performance since bulky properties are maintained by external force during the storage and transfer thereof by being rolled after manufacture through improved shape stability due to the improvement of compression recovery and rebound resilience.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a fiber aggregate having excellent sound absorption performance,

The present invention relates to a fiber assembly having excellent sound absorption performance and a method for manufacturing the same, and more particularly, to a fiber assembly having excellent sound absorption performance, which has improved compression recovery rate and rebound elastic modulus and improved sound absorption at low frequency band as well as high frequency band. will be.

Such as a vacuum cleaner, a dishwasher, a washing machine, an air conditioner, an air purifier, a computer, a projector, and the like, and the problem of noise pollution becomes more serious. Therefore, efforts to block or reduce the noise generated from various noise sources in the modern life are continuing, and in the developed countries, the legal regulations to regulate the noise level between the interlayer and the generation of apartment houses and apartments are increasingly strict . In addition, the noise introduced into the automobile interior is typically generated by the engine, such as the engine noise transmitted through the vehicle body or the air, and the friction sound with the wheel and the ground. In order to suppress such noise, the engine cover and the hood insulation are used The effect of reducing the noise is insignificant, and the dash outer, the dash inner, and the floor carpet attached to the outside of the vehicle play a role of removing most of the noise.

There are two ways to improve the noise. One is to improve the sound absorption performance and the other way to improve the sound insulation performance. Sound absorption is the sound energy that is transmitted through the inner path of the material and is converted into heat energy and disappears. And is reflected and shielded by the shield.

Felt, sponge, polyurethane foam and the like are conventionally used as suction and sound insulating materials conventionally used. In addition, sound absorbing materials impregnated with a thermoplastic resin or a thermosetting resin in compressed fiber, glass fiber, rock surface, or regenerated fiber are listed . However, most of the sound absorbing materials described above have insufficient sound insulating properties, and most of the sound absorbing materials contain harmful components to the human body.

In recent years, regulations on environmental friendliness and recyclability have gradually been strengthened, and the use ratio of fiber-absorbing materials based on thermoplastic resin such as PET or PP (polypropylene) is increasing. In order to reduce carbon dioxide, the regulation of fuel efficiency of the vehicle is gradually increasing. The improvement of fuel efficiency can be attained through the weight reduction of parts, so it is necessary to develop lightweight sound absorbing material with improved performance.

Accordingly, research and development on a sound absorbing material which is harmless to the human body and excellent in the sound absorbing function capable of effectively absorbing and reducing the noise while reducing the thickness has been actively conducted.

As a sound absorbing material that has been conventionally researched and developed, there is disclosed a sound absorbing material which is a web in which general short fibers having a diameter of 10 탆 or more are crimped to a general meltblown fiber in an amount of 10 wt% or more, A sound absorbing material and a heat insulating material which are in the form of a web containing a silane coupling agent and a silane coupling agent are disclosed. However, since the porosity of a web made of a general meltblown fiber is very large and the structure is not so dense, , There is a problem that the thickness of the sound absorbing material must be greatly increased to provide a sufficient sound absorbing effect.

 Although a three-dimensional nonwoven web made of a meltblown microfine fiber is disclosed, a three-dimensional nonwoven web has a large porosity and thus is not densely structured, resulting in insufficient durability. It is necessary to increase the thickness of the three-dimensional nonwoven web significantly, and it is difficult to manufacture the nonwoven web composed of three dimensions as described above, which increases the manufacturing cost significantly.

 In addition, meltblown nonwoven fabrics having a single structure having a density of 50 to 4,000 g / m 2 made of fibers having an average diameter of 0.1 to 20 μm have been disclosed in meltblown nonwoven fabrics having excellent sound absorption properties and heat insulating properties, The nonwoven fabric also has a problem that the soundproofing performance is not improved much as compared with the conventional sound absorbing material.

In addition, although a sound absorbing material is disclosed in which staple fibers that can be fused to the meltblown fibers by heat are included in order to impart steric stability, such a sound absorbing material still has a problem of insufficient soundproofing performance.

In addition, a sound absorbing material using a honeycomb structure having a plurality of spaces together with meltblown fibers has been disclosed. However, such a sound absorbing material is insufficient in soundproof performance and has a problem in that it is limited in its application because of lack of flexibility.

However, the development of a sound-absorbing material exhibiting a superior sound-absorbing effect while reducing the thickness and weight of the sound-absorbing material is insufficient, and development of a shielding product that provides sufficient sound-absorbing property even at a low frequency is still required In fact. In addition, there is a problem in that the sound absorption performance is reduced by compression and deformation due to external force generated after transportation, storage, attachment, etc., and it is necessary to develop a technology for sound absorbing material having excellent sound absorption while securing shape stability.

 The present invention has been made to solve the above problems, and an object of the present invention is to provide a fiber assembly having excellent sound absorption performance while reducing the thickness of the sound absorbing material and exhibiting excellent sound absorption in the high frequency as well as the low frequency band. In addition, the compression recovery rate and rebound elastic modulus is improved to show excellent morphological stability, thereby providing a high elastic fiber assembly excellent in sound absorption performance that can maintain its inherent properties without changing the shape for a long time after the production and a method of manufacturing the same.

 In order to solve the above problems, the present invention,

(1) preparing a staple fiber comprising a low melting point (LM) thermoplastic elastomer; (2) preparing a fiber assembly by incorporating staple fibers including the low melting point (LM) thermoplastic elastomer in the process of spinning the meltblown fibers; And (3) at least one of the upper and lower surfaces of the fiber assembly is heat-treated to provide a method for producing a fiber assembly having excellent sound absorption performance by densifying the heat treated portion.

According to an exemplary embodiment of the present invention, the staple fiber including the low melting point (LM) thermoplastic elastomer may have an elastic recovery rate of 50% or more.

According to another preferred embodiment of the present invention, the melting point of the low melting point (LM) thermoplastic elastomer (Elastomer) may be 140 to 160 ℃.

According to another preferred embodiment of the present invention, step (2) may be incorporated so that 15 to 50% by weight of a staple fiber including a low melting point (LM) thermoplastic elastomer (Elastomer).

According to another preferred embodiment of the present invention, the heat treatment temperature of step (3) may be 140 to 170 ℃.

According to another preferred embodiment of the present invention, the heat treatment time of step (3) may be 5 to 25 minutes.

The present invention also relates to a meltblown fiber; And a staple fiber comprising a low melting point (LM) thermoplastic elastomer. The fiber assembly comprising a layer structure of a high density layer and a low density layer provides an excellent sound absorbing performance.

According to a preferred embodiment of the present invention, the average density difference between the high density layer and the low density layer may be 2.75 kg / m ³ to 28.468 kg / m ³ .

According to another preferred embodiment of the present invention, the average density of the high density layer is 4.5 kg / m ³ to 30 kg / m ³ , the average density of the low density layer is 1.2 kg / m ³ to 2.3 kg / m ³ can be have.

According to another preferred embodiment of the present invention, the fiber assembly may include a high density layer on both the upper and lower sides of the low density layer.

According to another preferred embodiment of the present invention, the staplefiber may be a composite fiber spun with a low melting point (LM) thermoplastic elastomer (Elastomer) as one component.

According to another preferred embodiment of the present invention, a staple fiber including a low melting point (LM) thermoplastic elastomer may have an elastic recovery rate of 50% or more.

According to another preferred embodiment of the present invention, the melting point of the low melting point (LM) thermoplastic elastomer (Elastomer) may be 140 to 160 ℃.

According to another preferred embodiment of the present invention, the low melting point (LM) thermoplastic elastomer (Elastomer) is dimethyl terephthalate (dimethyl terephthalate (DMT) and dimethyl isophthalate (dimethyl isophthalate: DMI) or terephthalic acid (Terephthalic acid: TPA) and isophthalic acid (IPA) as diacids, 1,4-butanediol (1,4-Butanediol: 1,4-BD) and polytetramethyleneglycol (PTMG) as diols Diol) can be prepared through esterification and polymerization step.

According to another preferred embodiment of the present invention, the fiber assembly may include 15 to 50% by weight of staple fibers including a low melting point (LM) thermoplastic elastomer (Elastomer).

In addition, the present invention is a meltblown fiber (meltblown fiber); And a staple fiber comprising a low melting point (LM) thermoplastic elastomer, wherein the fiber assembly includes a thickness of 20 mm or less and a surface density of 400 g / m.²Below Provides a fiber assembly having excellent sound absorption performance of the absorption coefficient by the Alpha Cabin is 0.50 or more at 500Hz, 0.90 or more at 1000Hz.

According to a preferred embodiment of the present invention, the fiber aggregate may include a layered structure of a high density layer and a low density layer having a difference in average density of 2.75 kg / m ³ to 28.468 kg / m ³ .

The fiber aggregate having excellent sound absorption performance of the present invention exhibits excellent sound absorption effect while reducing the thickness of the sound absorbing material, and in particular, can exhibit a significantly improved sound absorption rate even in a low frequency band of 1000 Hz or less. In addition, since the bulky property at the time of manufacture is not lost by the external force in the course of being manufactured, rolled, stored, and transported by securing excellent shape stability by improvement of compression recovery rate and rebound resilience, It may not occur.

1 is a cross-sectional view of a fiber assembly forming a high density-low density layered structure according to a preferred embodiment of the present invention.
2 is a cross-sectional view of a fiber assembly forming a high density-low density-high density layered structure according to a preferred embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

As described above, the conventional sound absorbing product has a problem of increasing the area density and thickness of the fiber aggregate in order to improve the sound absorption performance and the sound insulation performance by increasing the porosity and the sound dissipation path. In particular, There is a problem that can not be done. In addition, there has been a problem that the sound absorption performance is reduced due to compression and shape deformation caused by external force generated after transportation, storage, or attachment.

Accordingly, in the present invention, meltblown fiber; And a staple fiber comprising a low melting point (LM) thermoplastic elastomer, wherein the fiber assembly comprises a fiber assembly having excellent sound absorption performance including a layer structure of a high density layer and a low density layer. I sought to solve a problem. As a result, the sound absorption may be improved while reducing the thickness of the sound absorbing material, and in particular, the sound absorption may be excellent even in a low frequency band. In addition, the compressive recovery rate and the rebound elastic modulus may be improved to provide a fiber assembly having excellent sound absorption performance, which can maintain its inherent characteristics without changing its shape for a long time after production, and a method of manufacturing the same.

 Specifically, FIG. 1 is a cross-sectional view of a fiber assembly having excellent sound absorption performance according to a preferred embodiment of the present invention, which includes a meltblown fiber 11 and a low melting point (LM) thermoplastic elastomer. It includes staple fibers 12 and forms a layered structure of the high density layer 200 and the low density layer 100.

The meltblown fiber 11 and the staple fiber 12 are formed in a layered structure with a low density layer 100 that is bulky and a high density layer 200 that is densely included. As a result, the sound absorption performance is improved while the thickness is reduced, and in particular, the sound absorption may be excellent even in a low frequency band.

An average density difference between the low density layer 100 and the high density layer 200 may be 2.75 kg / m ³ to 28.468 kg / m ³ . If the average density difference between the low density layer 100 and the high density layer 200 is less than 2.75 kg / m ³ , there may be a problem that the sound absorption performance effect of the low frequency region due to the vertical density difference is not expressed, and exceeds 28.468 kg / m ³ In this case, due to excessive density increase of the high density layer, the thickness of the fiber structure may be so thin that it does not contain sufficient air, and thus the sound absorbing performance may be rather deteriorated.

More preferably, the average density of the high density layer 200 is 4.5 to 30 kg / m³The average density of the low density layer 100 is 1.2 to 2.3 kg / m³Lt; / RTI > The average density of the high density layer 200 is 4.5 kg / m³Less than In this case, the density difference with the low density layer 100 may be small, and thus there may be a problem in that the sound absorption rate improvement effect of the low frequency region is insufficient, and 30 kg / m³If exceeds There may be a problem that the sound absorption is reduced due to the excessive air density decreases the air layer. The average density of the low density layer 100 is 1.2 kg / m³If less than too low density, sound absorption performance is reduced, 2.3 kg / m³If it exceeds, the difference in density with the high-density layer 200 is small, in particular, there may be a problem that the sound absorption of the low frequency region is reduced.

The weight of the high density layer 200 is preferably about 30 to 60% of the total fiber assembly. If the weight of the high-density layer 200 is out of the above range, the thickness of the high-density layer 200 is too thin to improve the sound absorbing effect, or if the high-density layer 200 is too thick, the bulkyness of the fiber assembly. This too can be a problem of falling sound absorption rather falling apart.

The fiber assembly of the present invention is not particularly limited as long as it includes at least one layered structure of the low density layer 100 and the high density layer 200, and more preferably, the low density layer 100 as shown in FIG. The upper and lower surfaces of the high density layers 200 and 300 may be included. When the high density layers 200 and 300 are formed on both the upper and lower surfaces of the low density layer 100, the sound absorption effect of the noise coming into both the upper and lower sides is more excellent, and the improvement of the sound absorption rate in the low frequency band is also remarkably large. As shown in FIG. 2, even when the high density layers 200 and 300 are formed on both sides of the low density layer 100, the sum of the weights of the high density layers 200 and 300 is about 30 to 60% of the total fiber aggregate weight. It is preferable that it is%.

 The fiber aggregate forming the layered structure of the low density layer 100 and the high density layers 200 and 300 is a short fiber including a meltblown fiber 11 and a low melting point (LM) thermoplastic elastomer. staple fiber 12.

First, the meltblown fibers 11 forming the fiber assembly of the present invention are not particularly limited as long as they are typically meltblown to form meltblown fibers, but more preferably, May be a single or mixed form of polypropylene, polyethylene, polyamide, polyester or polycarbonate and the like.

The meltblown fiber 11 may have a diameter of about 1.0 μm to about 8.5 μm. If the diameter of the meltblown fiber 11 is less than 1.0 μm, the manufacturing cost is greatly increased, and if the diameter is more than 8.5 μm, the structure of the fiber aggregate is not densely formed, which results in sound absorption performance of the sound absorbing material. And durability deterioration.

  Next, the staple fiber 12 included in the fiber assembly of the present invention includes a low melting point (LM) thermoplastic elastomer.

 Elastomer refers to a polymer material having a remarkable elasticity such as rubber, that is, a polymer having elongation when applied with an external force and returning to its original length when an external force is removed.

The staple fiber 12 of the present invention includes a low melting point (LM) thermoplastic elastomer and thus has a low melting point (LM) through hot air and heat treatment during the spinning process. It can increase the point bonding between staple fiber 12 and meltblown fiber 11, make the entanglement more tightly, and further heat treatment on the fiber assembly and the lower surface. By densifying the heat-treated and heat-treated portions, it is possible to form a layered structure including a low density layer and a high density layer. In addition, since the staple fiber 12 including the low melting point (LM) thermoplastic elastomer (Elastomer) is mixed, it is possible to improve the resilience of the fiber assembly to achieve excellent shape stability and compression recovery rate.

The melting point of the low melting point (LM) thermoplastic elastomer included in the staple fiber 12 of the present invention may be 140 to 160 ° C. When the melting point of the low melting point (LM) thermoplastic elastomer is out of the above range, the staple fibers 12 and the meltblown fibers during hot air and heat treatment during the spinning process The binding with the meltblown fiber 11 may not be sufficiently achieved, and it may be difficult to form a high density layer through additional heat treatment.

In addition, the staple fiber 12 of the present invention may have an elastic recovery rate of 50% or more, and more preferably, an elastic recovery rate of 50 to 80%. When the elastic recovery rate is less than 50%, the fiber assembly is hard and the flexibility is insufficient, so that the sound absorbing performance may be reduced. If the content is more than 80%, there may be a problem in that the processability of the fabric assembly is decreased as well as the manufacturing cost of the polymer itself is increased.

Conventionally, the elastic modulus (ASTM D 3574) of the fiber aggregate sound absorbing material is insufficient, so that the vibration transmitted to the matrix structure is not sufficiently attenuated, and thus the sound absorption rate is lowered, and the shape stability is inferior. The low melting point (LM) thermoplastic elastomer (Elastomer) in the fiber 12, and the elastic recovery rate is preferably 50 to 80%, the resilience of the fiber assembly (ASTM D 3574) up to 50 to 80% Increase the vibration damping ability, which is ultimately transmitted into the matrix, improve sound absorption and transmission loss, and maintain its inherent properties without prolonged morphology after manufacture.

The low melting point (LM) thermoplastic elastomer may be a polyester, a polyolefin, a polyamide, a polystyrene, a polyvinyl chloride, or a polyurethane.

More preferably, the low melting point (LM) thermoplastic elastomer is selected from the group consisting of dimethyl terephthalate (DMT), dimethyl isophthalate (DMI), terephthalic acid (TPA) and isophthalic acid Isophthalic acid (IPA) as an acid component (Diacid), 1,4-butanediol (1,4-BD) and polytetramethyleneglycol (PTMG) as a diol component And polymerization steps.

 The acidic component (Diacid) is obtained by using dimethyl terephthalate (DMT), dimethyl isophthalate (DMI) or terephthalic acid (TPA) and isophthalic acid (IPA), and dimethyl terephthalate (DMT) and terephthalic acid (TPA) react with the diol component to form a crystalline region. Dimethylisophthalate (DMI) and isophthalic acid (IPA) react with the diol component to form an amorphous region, .

The molar ratio of dimethyl terephthalate (DMT) to dimethyl isophthalate (DMI) is preferably in the range of 0.65 to 0.80: 0.2 to 0.35, and the molar ratio of terephthalic acid (TPA) to isophthalic acid (IPA) 0.2 to 0.35. The molar ratio of dimethyl isophthalate (DMI) to isophthalic acid (IPA) is less than the above range, the elastic recovery rate may be lowered, the low melting point function may not be exhibited and dimethyl isophthalate (DMI) and isophthalic acid ) Is more than the above range, the physical properties may be lowered.

The diol component is 1,4-butanediol (1,4-BD), and polytetramethyleneglycol (PTMG). 1,4-butanediol reacts with an acid component to form crystals And PTMG forms an amorphous region by reacting with an acid component to impart a low melting point function and an elastic force.

The mixing ratio of 1,4-butanediol (1,4-BD) and polytetramethylene glycol (PTMG) is preferably in a molar ratio of 0.85 to 0.95: 0.05 to 0.15. The molar ratio of the polytetramethylene glycol (PTMG) is less than the above range, the elastic recovery rate may be lowered, the low melting point function may not be exhibited, and the molar ratio of dipotetramethylene glycol (PTMG) The physical properties may be deteriorated. 1,4-butanediol (1,4-BD) can be mixed with ethylene glycol (EG) within the above range.

The polytetramethylene glycol (PTMG) preferably has a molecular weight of 1,500 to 2,000. The elasticity and physical properties of a low melting point (LM) thermoplastic elastomer produced when the polytetramethylene glycol (PTMG) is out of the range of the molecular weight may not be suitable for use.

It is preferable that the acid component and the diol component are mixed and polymerized at a molar ratio of 0.9 to 1.1: 0.9 to 1.1. If the acid component and the diol component are mixed too much, the acid component and the diol component are preferably used in a similar amount.

Dimethyl terephthalate (DMT), dimethyl isophthalate (DMI) as the acid component (Diacid) 1,4-butanediol (1,4-BD), polytetramethylene glycol (PTMG) as the diol component (Diol) as described above Low melting point (LM) thermoplastic elastomer (Elastomer) to be prepared may be prepared at a melting point of 140 ~ 160 ℃, elastic recovery rate of 50 to 80%.

 Furthermore, the staple fiber 12 of the present invention may be a composite fiber in which the low melting point (LM) thermoplastic elastomer is composite spun as one component. More preferably, it may be a sheath-core type or a side by side type of composite fiber, and when the sheath-core type composite fiber is formed, the low melting point ( LM) Thermoplastic elastomer (Elastomer) can be used as the sheath component, and general polyester, polyamide, polypropylene and the like can be used as the core component. The core component lowers the manufacturing cost, serves to support the fiber, and the low melting point (LM) elastomer allows the elastic force and the low melting point function to be expressed.

The weight ratio of the low melting point (LM) thermoplastic elastomer to the general polyester is preferably 40:60 to 60:40. If the weight ratio of the low melting point (LM) thermoplastic elastomer is less than 40, the elasticity and low melting point function may be deteriorated. If the weight ratio is more than 60, the manufacturing cost is increased.

The fiber length of the staple fiber 12 may be 20 to 70 mm, and if less than 20 mm, there may be a problem in that a stable structure cannot be formed due to detachment and heterogeneous mixing of the staple fiber 12. And, if it exceeds 70 mm there may be a problem that the sound absorption rate may be lowered because the number of individuals compared to the same weight. In addition, the fineness of the staple fiber 12 may be 5 to 8 D, and when the fineness of the staple fiber 12 is less than 5 D, there is a problem that the manufacturing cost is excessively increased compared to the performance improvement. And, if it exceeds 8 D, there may be a problem that the number of individuals is small and the effect expression due to the short fiber incorporation is reduced.

The fiber assembly having excellent sound absorption performance of the present invention may include 50 to 85% by weight of the meltblown fiber 11 and 15 to 50% by weight of the staple fiber 12. When the staple fiber 12 is less than 15% by weight, there is not enough air in the fiber assembly, so that the effect of incorporating the short fiber may not be expressed. Less fibers can cause problems with sound absorption at higher frequencies.

The fiber assembly, which consists of meltblown fibers 11 and staple fibers 12 dispersed therein, has one surface or amount of the fiber assembly for improving strength and maintaining its shape. It is preferable that the support layers 20 and 30 of constant thickness are formed on the surface.

To this end, it is applied for the interior material cover on the surface of the fiber assembly consisting of a meltblown fiber (11) and a staple fiber (12) comprising a low melting point (LM) thermoplastic elastomer (LM). Various known materials such as nonwoven fabric, woven fabric, knitted fabric, foam, film, paper, spanbond fabric, melt blown fabric, staple web, etc. may be used alone or Alternatively, the support layers 20 and 30 formed by combining two or more kinds may be formed. The supporting layers 20 and 30 cover the surface of the sound absorbing material applied to the interior of the vehicle or the inside of the building to maintain the shape of the sound absorbing material and to provide strength, and at the same time, the staple fibers 12 of the sound absorbing material Is also prevented from being released, so that the sound-absorbing function can be continuously maintained.

The above-described fiber assembly having excellent sound absorption performance includes the steps of: (1) preparing a staple fiber comprising a low melting point (LM) thermoplastic elastomer; (2) preparing a fiber assembly by incorporating staple fibers including the low melting point (LM) thermoplastic elastomer in the process of spinning the meltblown fibers; And (3) a method for producing a fiber assembly having excellent sound absorption performance by densifying a heat-treated portion by heat treatment on at least one surface of the upper and lower surfaces of the fiber assembly.

In order to manufacture the fiber assembly having excellent sound absorption performance of the present invention, the above-mentioned staple fiber 12 is mixed in the inside of the nonwoven fabric in which melt blow molding is in progress by high-pressure airflow so that the fiber assembly is uniformly dispersed. After fabrication, additional heat treatment may be performed on at least one of the upper and lower surfaces of the fabric assembly to form a layered structure of a high density layer and a low density layer. Details of the staple fiber 12 including the meltblown fiber 11 and the low melting point LM thermoplastic elastomer, which are equally applicable to the method of manufacturing the sound absorbing material of the present invention. Description will be omitted below.

 In order to form a layered structure of a high density layer and a low density layer, after fabrication of a fiber assembly comprising a staple fiber comprising a meltblown fiber and a low melting point (LM) thermoplastic elastomer (Elastomer) Further heat treatment is applied to the upper and / or lower surface of the fabric assembly.

The heat treatment temperature may be 140 to 170 ℃. If the heat treatment at a temperature below 140 ℃ is difficult to form a high density layer having a sufficient density difference with the low density layer, there may be a problem that the sound absorption is not improved, if the temperature exceeds 170 ℃ the density of the high density layer formed is too large, rather the sound absorption rate This may be a problem that the efficiency of sound absorption is improved compared to the increase in manufacturing cost due to the lowered or increased heat treatment temperature.

In addition, the heat treatment time may be 5 to 25 minutes, when the heat treatment is less than 5 minutes, it is difficult to form a high-density layer having a sufficient density difference with the low-density layer, there may be a problem that the sound absorption improvement is insufficient, if more than 25 minutes There may be a problem that the density of the high density layer becomes too large, or the longer heat treatment time may not affect the formation of the high density layer.

The upper and / or lower surface of the heat treated fiber assembly may be densified to form a high density layer, and may form a low density layer and a layered structure. By forming a layered structure including a high density layer and a low density layer, the sound absorption rate is improved, and in particular, it is possible to exhibit a significantly improved sound absorption rate even in a low frequency band of 1000 Hz or less.

 Fiber assembly having excellent sound absorption performance of the present invention prepared as described above 20 mm thick, surface density 400 g / m²Below The absorption coefficient by the Alpha Cabin method may be 0.50 or more at 500 Hz and 0.90 or more at 1000 Hz.

 The fiber aggregate having excellent sound absorption performance of the present invention may exhibit a significantly improved sound absorption rate of 0.50 or more and 0.90 or more in a low frequency band of 500 Hz and 1000 Hz by forming a layered structure including a high density layer and a low density layer.

Conventionally, it has been difficult to satisfy excellent sound absorption performance in both high frequency and low frequency bands while securing form stability. However, the fiber aggregate having excellent sound absorption performance of the present invention can satisfactorily satisfy excellent shape stability and sound absorption ratio. Accordingly, the sound absorbing material of the present invention can be used not only for a sound absorbing material for automobiles or for a train, a ship, an airplane, etc., which blocks external noises from entering into a vehicle interior, but also for an electronic product using motor parts. It can be used variously to improve.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples should not be construed as limiting the scope of the present invention, and should be construed to facilitate understanding of the present invention.

≪ Example 1 >

In order to prepare low melting polyester elastomer short fibers to be mixed, a mixture of 75 mol% terephthalic acid and 25 mol% isophthalic acid is used as an acid component, and 8.0 mol% of poly (tetramethylene ether) glycol is used as a diol component. A low melting point polyester having a melting point of 140 ° C., an intrinsic viscosity of 1.4 and an elastic recovery rate of 85% by polymerization by mixing the acid component and the diol component in a molar ratio of 1: 1 using a mixture of 92.0 mol% of 4-4-butanediol. System elastomer short fibers were prepared.

The molten resin of polypropylene is extruded through a plurality of orifices at a temperature of 265 ° C. and at the same time, hot air is supplied and the distance from the die to the focusing apparatus is maintained at 400 mm to obtain a polypropylene melt blown yarn having an average diameter of 2.5 μm. At the same time, a low melting polyester elastomer short fiber (6 denier) having an average length of 38 mm was mixed using a vertical downdraft, which is a method of mixing short fibers. Polypropylene melt blown yarn: short fibers = 65% by weight: to 35% by weight to prepare a fiber aggregate of a basis weight of 300g / ㎡.

After fabrication of the fiber assembly, heat treatment was performed on the upper and lower surfaces of the fiber assembly for 15 minutes using an IR heater at 145 ° C. to form a high density, low density, and high density layered structure by densifying the upper and lower layers. The upper and lower surfaces of the high density layer were about 60% by weight of the entire fiber assembly, the average density of the high density layer was 4.5 kg / m ^3, and the average density of the low density layer was 1.75 kg / m ³ .

≪ Example 2 >

Except that the heat treatment was performed only on the upper surface of the fiber assembly was prepared in the same manner as in Example 1 except that a high density-low density layered structure was formed.

≪ Example 3 >

The fiber assembly was prepared in the same manner as in Example 1 except that the average density of the high-density layer was 3.0 kg / m ³ by performing heat treatment on the upper and lower surfaces of the fiber assembly using an IR heater at 120 ° C. for 5 minutes.

<Example 4>

The heat treatment was carried out in a mold having a height of 10% lower than the total thickness of the fiber assembly, and was prepared in the same manner as in Example 1 except that the average density of the high density layer was 32 kg / m ³ .

&Lt; Comparative Example 1 &

Instead of short fibers containing a low melting point (LM) polyester-based elastomer, it contains ordinary polyester short fibers having a melting point of 260 ° C. and an intrinsic viscosity of 0.65, except that the upper and lower surfaces of the fiber assembly are not heat-treated. And was prepared in the same manner as in Example 1.

&Lt; Comparative Example 2 &

Except that the heat treatment was not performed on the fiber assembly, the lower surface was prepared in the same manner as in Example 1.

<Experimental Example>

In order to evaluate the sound absorption performance, rebound elastic modulus, and compression recovery rate of the fiber aggregates prepared according to Examples 1 to 4 and Comparative Examples 1 and 2, experiments were performed according to the following measurement methods, and the results are shown in Tables 2 and 3 below.

1. Thickness

The average value was measured 20 times over the entire width using a thickness gauge.

2. Absorption rate

For the measurement of the sound absorption rate, three specimens were prepared for each test piece applicable to the ISO R 354, Alpha Cabin method. The absorption coefficient was measured and the average value of the measured absorption coefficient was shown in Table 3.

3. Elasticity recovery rate

The elastic recovery rate was measured by measuring the elongated length after recovering 200% of the specimen of 2 mm thickness and 10 cm length at the speed of 200% / minute using Dumbbell (Instron) And was obtained by the following formula.

Elastic recovery rate (%) = {[20- (L-10)] / 20]} x100

(L: elongated length)

4. Ball Rebound

The height of the rebound was measured by dropping iron beads on a test piece at a constant height. (JIS K-6301, unit:%) Test specimens were made with a length of 50 mm or more and a thickness of 50 mm or more. A steel ball with a weight of 16 g and a diameter of 16 mm was dropped on a test piece at a height of 500 mm, After the measurement, the rebound value was measured at least three times in succession within one minute in each of the three test pieces, and the median value was determined as the rebound resilience (%).

5. Compression Recovery Rate

Compression recovery rates were measured using the ASTM D6571 method under the following conditions. The compressive recovery rate (%) was calculated by calculating the thickness ratio after compression for a certain period of time using the thickness measured at a constant initial condition and the weight of 7.26 kg.

Sample size Plate size Experimental conditions (temperature and humidity) Experimental condition load 200 * 200 mm ² 230 * 230 * 6.35 mm ³ , 187 g 20 ~ 24 ℃, no humidity 7.26 kg

division thickness
(mm) Flaw 500Hz 1000Hz 2000Hz 3000Hz 4000 Hz Example 1 12.91 0.541 0.954 1.02 1.001 1.052 Example 2 13.3 0.501 0.941 1.00 0.997 1.031 Example 3 13.68 0.481 0.836 0.971 0.967 0.998 Example 4 10.78 0.460 0.829 0.959 0.956 0.987 Comparative Example 1 14.56 0.473 0.834 0.951 0.977 1.018 Comparative Example 2 14.58 0.463 0.846 0.961 0,977 1.001

division Compression recovery rate (%) Resilience modulus (%) Example 1 45 49 Example 2 44 46 Example 3 42 47 Example 4 43 47 Comparative Example 1 35 28 Comparative Example 2 40 45

As can be seen from Tables 2 to 3, Examples 1 to 4, which form an asymmetric structure having a difference in density by performing heat treatment on the top and / or bottom surfaces of the meltblown fiber assembly, are superior in sound absorption performance to the comparative examples. can do.

Specifically, it can be seen that Comparative Example 1, which does not perform a heat treatment and contains a short polyester fiber, does not satisfy the density difference of the present invention, thereby lowering the sound absorption rate, as well as the compression recovery rate and the rebound elastic modulus. On the other hand, Comparative Example 2, but the sound absorption is significantly lower than the Examples, it can be seen that the compression recovery rate and rebound elastic modulus is superior to Comparative Example 1 by incorporating short fibers containing a low melting thermoplastic elastomer.

Examples 3 and 4, in which the difference in density between the high density and low density layers were outside the scope of the present invention, were less effective in improving sound absorption than Example 1, and Example 1 of the high density-low density-high density layered structure had the best sound absorption. It was found to be remarkably superior in the low frequency region.

The present invention relates to a fiber aggregate excellent in sound absorption performance and a method of manufacturing the fiber aggregate, and more particularly to a sound absorbing material for automobiles or a train, a vessel, an aircraft, etc., The present invention relates to a fiber aggregate excellent in sound absorption performance which can be used for improving noise shielding performance even in electronic products using motor parts.

Claims (17)

(1) preparing a staple fiber comprising a low melting point (LM) thermoplastic elastomer;
(2) preparing a fiber assembly by incorporating staple fibers including the low melting point (LM) thermoplastic elastomer in the process of spinning the meltblown fibers; And
(3) phase of the fiber assembly; A method for producing a fiber assembly having excellent sound absorption performance by densifying a heat treated portion by performing heat treatment on at least one of the lower surfaces.

The method of claim 1,
A method for producing a fiber assembly having excellent sound absorption performance, characterized in that the staple fiber comprising a low melting point (LM) thermoplastic elastomer (Elastomer) has an elastic recovery rate of 50% or more.

The method of claim 1,
Melting point of the low melting point (LM) thermoplastic elastomer (Elastomer) is a method for producing a fiber assembly excellent in sound absorption, characterized in that 140 to 160 ℃. The method of claim 1,
Step (2) is a method for producing a fiber assembly having excellent sound absorption performance, characterized in that the low-melting point (LM) is incorporated so that staple fibers containing 15 to 50% by weight of a thermoplastic elastomer (Elastomer). The method of claim 1,
The heat treatment temperature of step (3) is a method for producing a fiber assembly excellent sound absorption, characterized in that 140 to 170 ℃. The method of claim 1,
The heat treatment time of the step (3) is a method for producing a fiber assembly excellent in sound absorption, characterized in that 5 to 25 minutes. Meltblown fibers; And
In the fiber assembly comprising; a staple fiber comprising a low melting point (LM) thermoplastic elastomer (Elastomer),
A fiber assembly having excellent sound absorption performance including a layered structure of a high density layer and a low density layer. 8. The method of claim 7,
The average density difference between the high density layer and the low density layer is 2.75 kg / m ³ to 28.468 kg / m ³ The excellent sound absorption performance of the fiber assembly. 8. The method of claim 7,
The average density of the high-density layer is 4.5 kg / m ³ to 30 kg / m ³ , the average density of the low density layer is 1.2 kg / m ³ to 2.3 kg / m ³ excellent sound-absorbing performance fiber assembly. 8. The method of claim 7,
The fiber assembly has excellent sound absorption performance, characterized in that it comprises a high density layer on both the upper and lower sides of the low density layer. 8. The method of claim 7,
Wherein the staple fiber is a composite fiber obtained by spinning a low melting point (LM) thermoplastic elastomer as a single component. 8. The method of claim 7,
A fiber assembly having excellent sound absorption performance, characterized in that the staple fiber comprising a low melting point (LM) thermoplastic elastomer (staple fiber) has an elastic recovery rate of 50% or more. 8. The method of claim 7,
The low melting point (LM) thermoplastic elastomer (Elastomer) has a melting point of 140 to 160 ℃ excellent sound absorption performance, the fiber assembly. 8. The method of claim 7,
The low melting point (LM) thermoplastic elastomer (Elastomer) is dimethyl terephthalate (DMT) and dimethyl isophthalate (DMI) or terephthalic acid (TPA) and isophthalic acid (Isophthalic acid: IPA). 1,4-Butanediol (1,4-BD) and polytetramethyleneglycol (PTMG) as diols are prepared by esterification and polymerization as diacids. Fiber assembly having excellent sound absorption performance, characterized in that. 8. The method of claim 7,
The fiber assembly has excellent sound absorption performance, characterized in that it comprises 15 to 50% by weight of staple fibers containing a low melting point (LM) thermoplastic elastomer (Elastomer). Meltblown fibers; And
In the fiber assembly comprising; a staple fiber comprising a low melting point (LM) thermoplastic elastomer (Elastomer),
Thickness 20mm or less, surface density 400 g / m²Below Fiber aggregate with excellent sound absorption performance by the Alpha Cabin method with a sound absorption rate of 0.50 or more at 500 Hz and 0.90 or more at 1000 Hz. 17. The method of claim 16,
The fiber assembly has excellent sound absorption performance, characterized in that it comprises a layered structure of a high density layer and a low density layer having a difference in average density of 2.75 kg / m ³ to 28.468 kg / m ³ .

Images