JP2006098890A - Sound-deadening material and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound-deadening material which shows superior sound absorbing properties and makes easy recyclability and low environmental load properties compatible and to provide its production method. <P>SOLUTION: The sound-deadening material is formed by stacking nonwoven fabric A made principally of polylactic acid fiber and nonwoven fabric B made principally of polylactic acid fiber, the nonwoven fabric B being on the top side. The manufacturing method thereof comprises: I. a manufacturing stage for the nonwoven fabric A, i.e. a stage of manufacturing the nonwoven fabric A made principally of polylactic acid fiber by a needle punch method or span lacing method; II. a manufacturing stage for the nonwoven fabric B, i.e. a stage of manufacturing the nonwoven fabric B made principally of polylactic acid fiber by a laminating method of a span bonding method, a melt-blowing method, or a span bonding and melt-blowing method, having 0.1 to 5 dtex fineness, 50 to 500 g/m<SP>2</SP>nonwoven's weight, and 10 to 30 cc/cm<SP>2</SP>/sec air permeability; and III. a laminating stage, i.e. a stage of joining and laminating both the nonwoven fabric A and nonwoven fabric B by coating at least one of surfaces of the nonwoven fabric A and nonwoven fabric B with a biodegradable adhesive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sound-absorbing material that is a fiber laminate mainly composed of polylactic acid, which is a natural circulation type environment-friendly material, and has excellent sound-absorbing properties, and a method for producing the same.

  In recent years, there is a concern about global warming caused by mass consumption of petroleum resources and depletion of petroleum resources associated with mass consumption, and environmental awareness is increasing on a global scale. In such a background, there is an urgent need for a natural circulation type environmentally friendly material that is made of plant-derived materials (biomass) and that eventually decomposes into water and carbon dioxide in the natural environment after use.

  However, such biodegradable polymers using biomass have problems of high production costs and low mechanical properties and heat resistance, and have not been used as general-purpose plastics. As a biodegradable polymer utilizing biomass that can solve these problems, polylactic acid, which is a kind of aliphatic polyester, is currently attracting the most attention. Polylactic acid is a polymer made from lactic acid obtained by fermenting starch extracted from plants. Among biodegradable polymers using biomass, it has the best balance of mechanical properties, heat resistance and cost. . Development of resin products, fibers, films, sheets and the like using this has been performed at a rapid pitch.

  Under such circumstances, the development of polylactic acid fibers is preceded by agricultural materials and civil engineering materials that make use of biodegradability, but subsequent large-scale applications include clothing, hygiene materials, bedding, Is also expected to be applied to automotive applications.

  In particular, since the enforcement of the Automobile Recycling Law was decided in January 2005, there is a strong demand for easy recyclability of automobiles and their components and reduction of environmental burden.

  As is well known, in automobile interior materials, a large amount of sound absorbing material is used in order to reduce noise from outside the vehicle to passengers. As these automobile sound-absorbing materials, many have been proposed such as glass fibers, urethane foam, miscellaneous felt, and those using high-melting thermoplastic fibers and low-melting thermoplastic fibers (for example, Patent Document 1 and Patent Document 2). reference).

However, although the sound absorbing material using these materials sufficiently satisfies the sound absorbing property, it is insufficient when considering the compatibility of the automobile material from the viewpoint of easy recyclability and low environmental load. Thus, the present condition is that the sound-absorbing material which consists of a raw material which has easy recyclability and has a low load with respect to an environment has not been proposed yet.
JP-A-7-3599 JP 2004-145180 A

  An object of the present invention is to solve such conventional problems, and to provide a sound-absorbing material that exhibits good sound-absorbing characteristics from low frequencies to high frequencies in addition to easy recyclability and low environmental load, and a method for manufacturing the same. Is.

In order to achieve the above object, the sound absorbing material of the present invention is a nonwoven fabric A having a fineness mainly composed of polylactic acid fibers of 0.5 to 10 dtex, a basis weight of 100 to 1000 g / m ² , and a thickness of 5 to 50 mm. And non-woven fabric B having a fineness of 0.1 to 5 dtex, a basis weight of 50 to 500 g / m ² , and an air permeability of 10 to 30 cc / cm ² / sec. Is the front side.

  The nonwoven fabric A is mixed with 50 to 100% by weight of polylactic acid fibers, and the nonwoven fabric B is mixed with 50 to 100% by weight of polylactic acid fibers. This sound absorbing material can be used as an interior material for automobile ceiling materials, line carpets, engine covers, door trims, rear parcels, trunks, and the like.

  Moreover, in order to solve the said subject, the manufacturing method of the sound-absorbing material of this invention consists of at least the following process.

I. Manufacturing process of nonwoven fabric A: Nonwoven fabric A having a fineness of mainly 0.5 to 10 dtex, a basis weight of 100 to 1000 g / m ² , and a thickness of 5 to 50 mm by a needle punch method or a spunlace method. Manufacturing process
II. Manufacturing process of nonwoven fabric B: Fineness mainly composed of polylactic acid fiber is 0.1 to 5 dtex, basis weight is 50 to 500 g / m ² , and air permeability is 10 by spunbond method, meltblown method or spunbond and meltblown method. The process of manufacturing the nonwoven fabric B which is the range of 30 cc / cm < ² > / sec by the spun bond method or the melt blow method or the lamination method of the spun bond and the melt blow method
III. Lamination process: The process of apply | coating a biodegradable adhesive to at least one side among the said nonwoven fabric A and the nonwoven fabric B, joining both nonwoven fabrics A and B, and laminating | stacking.

  In the laminating step, the adhesive is preferably applied by spraying.

  According to the present invention, by making a nonwoven fabric mainly composed of polylactic acid fiber into an appropriate configuration and combination, it is possible to obtain a sound-absorbing material having easy recyclability, low environmental load, and good sound-absorbing characteristics from low to high frequencies. Can do.

  As a result of intensive investigations for carrying out the above problems, the present inventors have found that the nonwoven fabric A has a specific fineness, basis weight, and thickness mainly composed of polylactic acid fibers, and a specific fineness and basis weight mainly composed of polylactic acid fibers. The present inventors have found that this problem can be solved at once by laminating the nonwoven fabric B having air permeability.

  Hereinafter, the best mode for carrying out the sound absorbing material of the present invention will be described in detail.

  First, as a fiber used for the nonwoven fabrics A and B of the present invention, it is necessary in the present invention that both are manufactured from polylactic acid. This is because polylactic acid fibers are superior to other non-petroleum polymers in terms of cost, spinnability, card passing property, and the like. Here, “polylactic acid fiber” refers to a polymer obtained by polymerizing lactic acid oligomers such as lactic acid and lactide, and the optical purity of L-form or D-form is preferably 90% or more, which increases the melting point and improves heat resistance. 97% or more is more preferable. A blend of polylactic acid having an optical purity of 90% or higher in the L form and polylactic acid having an optical purity of 90% or higher in the D form at a ratio of 70/30 to 30/70 is a preferable embodiment because the melting point is further improved. . In addition, in the range that does not impair the properties of polylactic acid, even if components other than lactic acid are copolymerized, polymers and particles other than polylactic acid, flame retardants, antistatic agents, matting agents, deodorants, antibacterial agents, You may contain additives, such as an antioxidant or a coloring pigment. In addition, a terminal blocker such as a carbodiimide compound may be contained for the purpose of suppressing hydrolysis of polylactic acid by hot water treatment such as dyeing and suppressing deterioration of physical properties of the product over time. The molecular weight of the polylactic acid polymer is preferably 50,000 to 500,000, and more preferably 100,000 to 350,000, as a weight average molecular weight with a good balance between mechanical properties and moldability.

  Moreover, from the point of improving the wearability and form stability when the nonwoven fabric is used, fibers made of other polymers may be mixed within a range where the mixing ratio does not exceed 50% by weight. For example, known fibers such as polyethylene terephthalate fiber, polybutylene terephthalate fiber, polytrimethylene terephthalate fiber, polyamide fiber, acrylic fiber, polyolefin fiber, aromatic polyamide fiber, and flame-resistant fiber. However, among these materials, those manufactured using non-petroleum-based raw materials do not violate the concept of the present invention of reducing the environmental load, and may be used in excess of 50% by weight. For example, propylene glycol, which is a raw material for polytrimethylene terephthalate fibers, is also known to be produced from non-petroleum-based raw materials. Polytrimethylene terephthalate fibers produced by such a production method account for 50% by weight. You may mix beyond.

  Next, the sound absorbing material of the present invention will be described for each component. First, the nonwoven fabric A used for the sound absorbing material will be described.

  The nonwoven fabric A used in the present invention needs to be formed of fibers having a fineness in the range of 0.5 to 10 dtex. When the fineness is larger than 10 dtex, sufficient sound absorbing properties cannot be obtained when the sound absorbing structure is formed. When the fineness is smaller than 0.5 dtex, it is difficult to manufacture by a normal melt spinning method, which increases the cost. This is because there is a problem that handling properties are lowered. The cross-sectional shape of the fibers forming the nonwoven fabric A is not particularly limited, and for example, known ones such as a circle, a triangle, and a flat shape can be used. Further, the fiber length is preferably in the range of 5 to 200 mm, and more preferably 30 to 150 mm, in which the passability when passing the short fibers through the card is good. Furthermore, as the fibers constituting the nonwoven fabric A, it is preferable to use short fibers that are crimped and that are easy to adjust the thickness and basis weight.

The nonwoven fabric A of the present invention needs to have a basis weight of 100 to 1000 g / m ² and a thickness of 5 to 50 mm. When the basis weight is 100 g / m ² and the thickness is less than 5 mm, the density and thickness for obtaining the sound absorbing effect are impaired, and sufficient sound absorbing properties cannot be obtained. On the other hand, when the weight per unit area is 1000 g / m ² and the thickness is larger than 50 mm, the weight and the thickness are too large, so that it is difficult to use as an automobile interior material.

  Furthermore, the nonwoven fabric A of the present invention can be made into a nonwoven fabric by mixing a core-sheath composite fiber in which a thermoplastic polymer having a melting point lower than that of the main polylactic acid fiber is arranged as a thermal bonding component. It is preferable for increasing strength and shape stability. In the heat-adhesive core-sheath composite fiber, the low melting point component is preferably in the range of 30 to 70% by weight because the effect of heat adhesion is good. Further, the melting point of the low melting point component is preferably lower by 40 ° C. or more than the polylactic acid fiber from the viewpoint of form stability after heat bonding.

  Next, the nonwoven fabric B used for the sound absorbing material of the present invention will be described.

  In order to improve the wearability and shape stability of the nonwoven fabric B, other fibers may be mixed within the range where the mixing ratio does not exceed 50% by weight, as with the nonwoven fabric A. For example, known fibers such as polyethylene terephthalate fiber, polybutylene terephthalate fiber, polytrimethylene terephthalate fiber, polyamide fiber, acrylic fiber, polyolefin fiber, aromatic polyamide fiber, and flame-resistant fiber can be used. If these fibers are mixed in excess of 50% by weight, the advantage of using non-petroleum fibers is impaired, which is not preferable. However, among these materials, when manufactured using a non-petroleum-based raw material, it does not violate the concept of reducing the environmental load, so it can be used in excess of 50% by weight. For example, propylene glycol, which is a raw material for polytrimethylene terephthalate fibers, is also known to be produced from non-petroleum-based raw materials. Polytrimethylene terephthalate fibers produced by such a production method account for 50% by weight. Can be mixed beyond.

  The nonwoven fabric B used for the sound absorbing material of the present invention needs to be formed of fibers having a fineness of 0.1 to 5 dtex. If the fineness is greater than 5 dtex, sufficient sound absorption cannot be obtained. On the other hand, if it is smaller than 0.1 dtex, the production becomes difficult, which not only increases the cost, but also reduces the handleability, which is not preferable.

Moreover, the fabric weight of the nonwoven fabric B needs to be in the range of 50 to 500 g / m ² . If it is less than 50 g / m ² , the air permeability becomes high and sufficient sound absorbing properties cannot be obtained, and if it exceeds 500 g / m ² , the weight of the sound absorbing material is increased, which is not preferable as an automobile interior material. Furthermore, the air permeability of the nonwoven fabric B needs to be in the range of 10 to 30 cc / cm ² / sec. If the air permeability is less than 10 cc / cm ² / sec, the sound absorption in the high frequency region is remarkably lowered. Therefore, if the air permeability is greater than 30 cc / cm ² / sec, this is not preferable. This is not preferable because the sound absorbing property in the case is lowered.

  By the way, although the nonwoven fabric A and the nonwoven fabric B which are the components of the sound-absorbing material of the present invention are both composed of a nonwoven fabric mainly composed of polylactic acid fibers, the nonwoven fabric A has an appropriate fineness, basis weight, and thickness. By doing so, it mainly plays a role of improving the sound absorption in the low frequency region, and the nonwoven fabric B plays a role of mainly improving the sound absorption effect in the high frequency region by adjusting to an appropriate fineness, basis weight, and air permeability. It is what you bear.

  Next, the sound absorbing material of the present invention requires that the above-described nonwoven fabric A and nonwoven fabric B are laminated. As the stacking order, it is preferable to dispose the non-woven fabric B on the front side, that is, the sound source side, because air permeability on the surface of the sound absorbing material is reduced, air movement is prevented, and a sound absorbing effect is exhibited. As a result, it is possible to obtain a sound absorbing material having a good sound absorbing property from a low frequency region to a high frequency region. Of course, a known functional process such as a flame retardant process or a flameproof process may be applied to the sound absorbing material of the present invention.

  The sound-absorbing material thus obtained is obtained by laminating two different types of non-woven fabrics, a non-woven fabric A having a specific fineness, basis weight, and thickness, and a non-woven fabric B having a specific fineness, basis weight, and air permeability. In addition to easy recyclability and low environmental impact, it is possible to achieve excellent sound absorption from the low frequency range to the high frequency range.

  Next, the manufacturing method of this invention is demonstrated in order of a process.

I. Manufacturing process of nonwoven fabric A First, a nonwoven fabric A mainly composed of polylactic acid fibers is manufactured. The nonwoven fabric A is manufactured by a needle punch method or a spunlace method because a nonwoven fabric excellent in form stability and strength can be manufactured by entanglement of fibers. As a specific method, for example, a short fiber made of polylactic acid is passed through an opener and a card machine to form a web, and then manufactured by a needle punch method, a water jet punch method, or the like.

  The fineness of the polylactic acid fiber used for the nonwoven fabric A is adjusted to a range of 0.5 to 10 dtex. When the fineness is larger than 10 dtex, sufficient sound absorbing properties cannot be obtained when the sound absorbing structure is formed. When the fineness is smaller than 0.5 dtex, it is difficult to manufacture by a normal melt spinning method, which increases the cost. The problem that handling property also falls occurs. As a specific method of adjusting the fineness, for example, in melt spinning, the fineness is adjusted by adjusting the amount of polymer discharged from the die and the take-up speed.

Moreover, it is preferable to use the short fiber which gave the crimp which can adjust thickness and a fabric weight easily, and the fiber which comprises the nonwoven fabric A may use either a mechanical crimp or a spiral crimp. . There are many means for imparting spiral crimps, for example, a method of making fibers have asymmetry in the cross-sectional direction to develop spiral crimps due to orientation difference during stretching, and a difference in shrinkage rate that occurs during relaxation heat treatment after stretching There is a method for developing spiral crimps.
Next, using the polylactic acid fiber obtained above, the basis weight is adjusted to 100 to 1000 g / m ² and the thickness is adjusted to a range of 5 to 50 mm. When the basis weight is 100 g / m ² and the thickness is less than 5 mm, the density and thickness for obtaining the sound absorbing effect are impaired, and sufficient sound absorbing properties cannot be obtained. On the other hand, when the weight per unit area is 1000 g / m ² and the thickness is larger than 50 mm, the weight and the thickness are too large, so that it is difficult to use as an automobile interior material. As a specific method for adjusting the basis weight and thickness, for example, the basis weight and the thickness are adjusted by adjusting the production speed and the number of needle hits when the web of the polylactic acid fiber obtained above is produced.

II. Manufacturing process of nonwoven fabric B Next, a nonwoven fabric B mainly composed of polylactic acid fibers is manufactured. Nonwoven fabric B is manufactured by a spunbond method, a melt blow method, or a lamination method such as a spun bond and a melt blow method from the viewpoint of cost and shape stability. Specifically, the spunbond method is, for example, by extruding a molten polymer from a nozzle nozzle, sucking and stretching it with a high-speed suction gas, and then collecting it on a moving conveyor to make a web, and further continuously heat-treating, A nonwoven fabric is manufactured by entanglement etc. Further, for example, in the melt-blowing method, for example, a heated high-speed gas fluid is sprayed on a molten polymer to draw the molten polymer into a fine fiber, and then collect this to produce a nonwoven fabric. The fineness of the polylactic acid fiber is adjusted to a range of 0.1 to 5 dtex. If the fineness is larger than 5 dtex, sufficient sound absorption cannot be obtained, and if it is smaller than 0.1 dtex, the production becomes difficult and not only the cost is increased, but also the handling property is lowered. Further, to adjust the basis weight in the range of 50 to 500 g / m ^2. If it is less than 50 g / m ² , the air permeability becomes high and sufficient sound absorbing properties cannot be obtained, and if it exceeds 500 g / m ² , the weight of the sound absorbing material is increased, which is not preferable as an automobile interior material.

  As a specific method for adjusting the fineness and basis weight, for example, in melt spinning, the fineness and basis weight are adjusted by adjusting the amount of polymer discharged from the die and the take-up speed.

Moreover, the air permeability of the nonwoven fabric B is adjusted to a range of 10 to 30 cc / cm ² / sec. If the air permeability is less than 10 cc / cm ² / sec, the sound absorption in the high frequency region is remarkably lowered. Therefore, if the air permeability is greater than 30 cc / cm ² / sec, this is not preferable. This is not preferable because the sound absorbing property in the case is lowered. Specific methods for adjusting the air permeability within such a range include appropriately adjusting the thickness of the nonwoven fabric, embossing the fibers forming the nonwoven fabric, and imparting a resin. In particular, emboss bonding is preferable because it can not only control the air permeability but also improve the fluffing, shape stability, tensile strength, and tear strength of the nonwoven fabric. Further, as the resin to be imparted to the fiber, a known resin can be used, and an acrylate resin, a urethane resin, a polyester resin, a silicone resin, or the like can be used. The adhesion amount of the resin is preferably in the range of 5 to 20% by weight from the balance of cost and performance.

III. Lamination process Subsequently, it is a process of laminating the nonwoven fabric A and the nonwoven fabric B, but it is necessary for the lamination to be bonded by a biodegradable adhesive from the convenience of disposal processing.

  Examples of the biodegradable adhesive include those made of starch, polybutylene succinate, polycacrolactone, and the like, but it is preferable to use a polylactic acid adhesive from the viewpoint of easy recycling.

  The bonding method is not particularly limited, and is a method of thermally bonding after laminating using a heat bonding sheet, a method of mixing heat-bonded short fibers in a fiber structure, and thermally bonding nonwoven fabrics, and spraying an adhesive. A method of spraying and bonding non-woven fabrics can be used. Among them, a method of spraying an adhesive and bonding non-woven fabrics is preferable in terms of ease of handling.

  By the method for producing a sound absorbing material of the present invention, it is possible to easily obtain a sound absorbing material having excellent sound absorbing properties in a wide range from a low frequency region to a high frequency region in addition to easy recyclability and low environmental load.

  Examples of the sound absorbing material of the present invention will be described below.

  In addition, the following method was used as a measuring method of the characteristic in an Example.

A. Fineness (dtex)
It calculated with the weighted average from the mixing rate of the short fiber nonwoven fabric measured according to JISL1015 (1999) 8.5.1.

  Moreover, the average fineness used in an Example represents the weighted average fineness at the time of using and mixing the fiber from which fineness differs. The nonwoven fabric produced by the spunpan bond method used a value calculated from the amount of polymer discharged from the die and the spinning speed.

B. Fiber length Measured according to JIS L 1015 (1999) 8.4.1.

C. Weight per unit (g / m ² )
Measured according to JIS L 1096 (1999) 8.4.2.

D. Thickness (mm)
Measured according to JIS L 1096 (1999) 8.5.1.

E. Air permeability (cc / cm ² / sec)
Measured according to JIS L 1096 (1999) 8.27.1.

F. Sound Absorption The normal incident sound absorption rate (%) was measured according to JIS A 1405 (1998).

G. Comprehensive evaluation Good sound-absorbing and non-petroleum-based resources were marked with ◯, one lacking either △, and lacking both.

Example 1
After passing through a spreader twice so that 90 g of polylactic acid short fiber with a fineness of 9 dtex × fiber length of 64 mm and 10 g of polyester binder fiber with a fineness of 4.4 dtex × fiber length of 51 mm are uniformly mixed, this fiber is weighed and parallel card Created a web on the machine. The prepared web is passed once from one side with a needle punch machine (number of needles 50 / cm ² ), the fibers are entangled, and the needle punch nonwoven fabric has an average fineness of 8.54 dtex and a basis weight of 200 g / m ² and a thickness of 10 mm. This was made into a nonwoven fabric A.

A non-woven fabric B was a polylactic acid spunbonded nonwoven fabric having a basis weight of 150 g / m ² and a fineness of 2.2 detex. The air permeability of this nonwoven fabric B was 11 cc / cm ² / sec.

Next, 10 g / m ² of an acrylic resin as an adhesive was applied to the non-woven fabric A by a spray method, and the non-woven fabric A and B were bonded together to obtain a sound absorbing material 1. The properties and evaluation results of the obtained sound absorbing material are shown in Table 1 described later.

Example 2
In order to make everything biodegradable, the binder fiber of the nonwoven fabric A is made of a polylactic acid / polybutylene succinate core-sheath composite cotton having a fineness of 4.4 dtex × fiber length of 51 mm, and a polylactic acid resin as an adhesive for the nonwoven fabrics A and B. A sound-absorbing material was prepared under the same conditions as in Example 1 except that it was used. The characteristics and evaluation results of this sound absorbing material are shown in Table 1 described later.

Example 3
In order to confirm the change in sound absorption due to the basis weight of the nonwoven fabric A, a sound absorbing material was prepared in the same manner as in Example 1 except that the basis weight was 100 g / m ² . The characteristics and evaluation results of this sound absorbing material are shown in Table 1 described later.

Example 4
In order to confirm the sound absorption when the fineness of the sound absorbing structure is reduced, the fiber having a fineness of 9 dtex is 50% by weight, the fiber having a fineness of 6.6 dtex is 20% by weight, the fiber having a fineness of 3.3 dtex is 20% by weight, and the fineness of 4 A sound-absorbing material was prepared in the same manner as in Example 1 except that non-woven fabric A having an average fineness of 6.92 dtex was used, in which the mixing ratio of 10% by weight of .4 dtex fibers and fine fibers was increased.
The characteristics and evaluation results of this sound absorbing material are shown in Table 1 described later.

Example 5
In order to confirm the change in sound absorption due to the difference in the nonwoven fabric B, a spunlace nonwoven fabric having an average fineness of 0.2 dtex, a basis weight of 150 g / m ² , and an air permeability of 13 cc / cm ² / sec was used for the nonwoven fabric B. A sound absorbing material was prepared in the same manner as in 1. The characteristics and evaluation results of this sound absorbing material are shown in Table 1 described later.

Comparative Example 1
A sound absorbing material was prepared in the same manner as in Example 1 except that the non-woven fabric B was not used. The characteristics and evaluation results of this sound absorbing material are shown in Table 1 described later.

Comparative Example 2
The nonwoven fabric B used in Example 1 was impregnated with a 20% concentration acrylic resin: T23M (manufactured by Kyoeisha Chemical Co., Ltd.) by the padding method, then squeezed with mangle and dried at 120 ° C. to obtain nonwoven fabric B ( A sound-absorbing material was prepared in the same manner as in Example 1 except that it was used as a basis weight after application of acrylic resin: 170 g / m ² and air permeability: 5.5 cc / cm ² / sec. Table 1 shows the characteristics and evaluation results of the sound absorbing material.

Comparative Example 3
A sound-absorbing material was prepared in the same manner as in Example 1 except that the nonwoven fabric A was a needle punched nonwoven fabric made of fibers having an average fineness of 13.4 dtex. Table 1 shows the characteristics and evaluation results of the sound absorbing material.

Comparative Example 4
A sound-absorbing material was prepared in the same manner as in Example 1 except that both the non-woven fabrics A and B used polyethylene terephthalate fibers instead of polylactic acid fibers. The characteristics and evaluation results of this sound absorbing material are shown in the following Table 1.

  As is apparent from Table 1, the sound absorbing material of the present invention uses polylactic acid, which is a non-petroleum material, and exhibits excellent sound absorbing properties.

  On the other hand, the sound absorbing material of the comparative example is not suitable as a sound absorbing material in terms of environmental load because it is inferior in sound absorbing property to the examples or uses a petroleum-based material.

  The sound-absorbing material of the present invention exhibits excellent sound-absorbing properties and achieves both easy recyclability and low environmental impact, and therefore can be suitably used for automotive applications, architectural applications, civil engineering applications, household appliance applications, and audio equipment applications. .

  Moreover, according to the method for producing a sound absorbing material of the present invention, it is possible to easily obtain a sound absorbing material having excellent sound absorbing properties in addition to easy recyclability and low environmental load.

Claims (6)

Non-woven fabric A having a fineness mainly composed of polylactic acid fibers of 0.5 to 10 dtex, a basis weight of 100 to 1000 g / m ² and a thickness of 5 to 50 mm, and a fineness mainly composed of polylactic acid fibers is 0.1 to A sound-absorbing material characterized in that 5 dtex, a basis weight of 50 to 500 g / m ² , and a non-woven fabric B having an air permeability of 10 to 30 cc / cm ² / sec are laminated to make the non-woven fabric B the front side.   The sound absorbing material according to claim 1, wherein polylactic acid fibers are mixed in the nonwoven fabric A in a range of 50 to 100% by weight.   The sound-absorbing material according to claim 1, wherein polylactic acid fibers are mixed in the nonwoven fabric B in a range of 50 to 100% by weight.   The automobile interior material, wherein the sound absorbing material according to any one of claims 1 to 3 is used as a ceiling material, a line carpet, an option mat, an engine part, a trunk part, a rear parcel, or a door trim of an automobile. . A method for producing a sound-absorbing material comprising at least the following steps.
I. Manufacturing process of nonwoven fabric A: Nonwoven fabric A having a fineness of mainly 0.5 to 10 dtex, a basis weight of 100 to 1000 g / m ² , and a thickness of 5 to 50 mm by a needle punch method or a spunlace method. Manufacturing process
II. Non-woven fabric B manufacturing process: Spun bond method, melt blow method, or spun bond and melt blow method, the fineness mainly composed of polylactic acid fiber is 0.1 to 5 dtex, the basis weight is 50 to 500 g / m ² , and the air permeability is 10 The process of manufacturing the nonwoven fabric B which is the range of 30cc / cm < ² > / sec
III. Lamination process: The process of apply | coating a biodegradable adhesive to at least one side of the said nonwoven fabric A and the nonwoven fabric B, joining both nonwoven fabrics A and B, and laminating | stacking.   6. The process for producing a sound absorbing material according to claim 5, wherein the adhesive is applied by spraying in step III of claim 5.