JP2013163869A - Molded acoustic material for dash silencer of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded acoustic material for dash silencer of vehicle with excellent sound absorbing property in a wide range of frequency range and with thin, lightweight and morphological stability.SOLUTION: An acoustic material comprises a surface material composed of a multilayered nonwoven fabric of polyester based fiber, and a substrate mainly composed of a recovered fiber felt, in which the surface material and the substrate are bonded. The surface material is a multilayered nonwoven fabric comprising at least three layers of an upper layer, a middle layer and a bottom layer that are thermally pressed and bonded with one another in a ratio partial thermal contact-bonding of 3 to 35%. The upper layer comprises a spun-bonded polyester-based filament with a fiber diameter of 10 to 30 μm. The middle layer comprises a melt-blow polyester-based ultrafine filament with a fiber diameter of 1 to 7 μm. The bottom layer comprises a spun-bonded polyester-based filament having a lower melting temperature than the upper layer by 30 to 150°C. The substrate is a nonwoven fabric comprising 40 to 95 wt.% of the recovered fiber felt and 5 to 60 wt.% of low melting temperature polyester-based fiber. The bottom layer of the surface material is bonded with the substrate.

Description

  The present invention relates to a sound-absorbing member in which a nonwoven fabric face material and a recycled cotton base material are joined. In particular, the sound-absorbing member has high sound-absorbing properties, and has press formability, light weight, recyclability, heat resistance, flame retardancy, and the like. The present invention relates to a molded sound-absorbing material used for a vehicle dash silencer that is excellent in noise reduction in an engine room or a dash panel in a vehicle.

Conventionally, glass wool, rock wool, aluminum fibers, porous ceramics and the like have been used as interior materials in automobiles and houses as sound absorbing materials.
In particular, sound absorbing materials using cotton fibers such as low-cost recycled jeans are used. The fiber weight increases in order to obtain the desired sound absorption, although it is inexpensive. As an improvement, for example, the following Patent Document 1 discloses that a repellent felt is formed by mixing a jeans repellent made from jeans manufacturing scraps and / or old jeans clothes and a binder fiber, and heat softening and heating by hot air is performed. A molded sound-absorbing mat having a density of 0.005 to 0.5 g / cm ³ has been proposed. However, in order to obtain a high sound absorption coefficient, there are problems such as an increase in thickness and weight.

Patent Document 2 below proposes a sound absorbing material for a vehicle in which a low melting point fusion fiber is blended with a cotton wool, denim hair, synthetic fiber, wool wool or acrylic fiber blend. There is no generation of formaldehyde in the phenolic resin used for resin felt, but there are problems such as an increase in thickness and weight in order to obtain a high sound absorption coefficient.
Furthermore, Patent Document 3 below discloses a composite sound-absorbing material in which the face material is made of a laminated nonwoven fabric containing low-melting fibers and the base material is made of a synthetic fiber nonwoven fabric. Although high sound absorption is obtained, it cannot be said that flame retardancy, heat resistance, moldability, etc. are sufficient for vehicles.

JP 2004-27383 A JP 2001-316963 A JP 2009-000843 A

  The object of the present invention is to solve the above-mentioned problems of the prior art and improve the combination of a face material and a base material, so that it is excellent in flame retardancy, heat resistance and moldability, and has high sound absorption. It is providing the molded sound-absorbing material used for a dash silencer.

  In view of the above problems, the present inventors have studied the combination of a face material and a base material. As a result, the nonwoven fabric having at least a three-layer structure in which a melt blown polyester-based ultrafine fiber layer is sandwiched between spunbonded polyester-based long fiber layers. Molding used for vehicle dash silencers with excellent flame retardancy, heat resistance and moldability, and high sound absorption, by using as a base material a nonwoven fabric containing repellent felt and low melting polyester fiber The inventors have found that a sound absorbing material can be obtained and have reached the present invention. That is, the present invention provides the following inventions.

(1) A sound-absorbing material used for a vehicle dash silencer in which a face material made of a laminated nonwoven fabric of polyester fibers and a base material mainly made of anti-fouling felt are bonded, and the face material has a fiber diameter of 10 to 30 μm. An upper layer made of a spunbond polyester long fiber, an intermediate layer made of a melt blown polyester fine fiber having a fiber diameter of 1 to 7 μm, and a lower layer containing a spunbond polyester long fiber having a melting point of 30 to 150 ° C. lower than the upper layer. It is a laminated nonwoven fabric in which at least three layers are thermocompression bonded at a partial thermocompression ratio of 3 to 35%, and the base material is a nonwoven fabric containing 40 to 95 wt% of repellent felt and 5 to 60 wt% of low-melting polyester fiber The lower layer of the face material is bonded to the base material, the thickness is 2 to 30 mm, the mass is 500 to 3000 g / m ² , and JIS-A-1405 A molded sound absorbing material used for a vehicle dash silencer having a sound absorption of 40% or more at a frequency of 2000 to 5000 Hz according to the normal incidence method.
(2) The molded sound absorbing material as described in 1 above, wherein the face material has a thickness of 0.1 to 0.5 mm and a basis weight of 20 to 100 g / m ² .
(3) The molded sound-absorbing material according to 1 or 2 above, wherein the mass ratio of the melt blown polyester-based ultrafine fibers of the face material is 5 to 40 wt%.
(4) The molded sound absorbing material according to any one of the above items 1 to 3, wherein the lower layer of the face material is a composite fiber of polyethylene terephthalate as a core and a polyester copolymer as a sheath.
(5) The molded sound absorbing material according to any one of (1) to (4), wherein the base material contains 3 to 40 wt% of a flame retardant with respect to the weight of the repellent felt.
(6) The molded sound absorbing material as described in 5 above, wherein the flame retardant is contained in the repellent felt.
(7) The molded sound absorbing material as described in 5 or 6 above, wherein the flame retardant is a phenol resin flame retardant.

The molded sound-absorbing material of the present invention can be preferably molded into a vehicle dash silencer by preheating or press-molding with a heated concave and convex mold, and has high sound absorption and sound insulation properties over a wide frequency range of 2000 to 5000 Hz. It has excellent heat resistance and rigidity.
Therefore, it is preferably used as a molded sound-absorbing material having a high sound-absorbing property over a wide frequency range in an automobile engine room, an automobile driver's dash silencer, and the like.

  The molded sound-absorbing material of the present invention is formed by bonding a face material and a base material, the face material is made of a laminated nonwoven fabric containing ultrafine fibers and low melting point fibers, and the base material is made of recycled anti-hair felt such as synthetic fiber. It is excellent in flame retardancy, heat resistance and moldability, and has high sound absorption and sound insulation properties over a wide frequency range, so it is suitable for a vehicle dash silencer.

The first feature of the molded sound-absorbing material of the present invention is that a laminated nonwoven fabric having a dense structure containing ultrafine fibers is used as a face material, and a layer containing low melting point fibers is formed on the side of the face material bonded to the base material. By doing so, good adhesion between the face material and the substrate and high sound absorption are obtained.
The second feature is that the face material includes a low-melting fiber, and the base material contains the low-melting fiber, thereby having good followability to the mold during press molding with a concavo-convex mold. A good molded sound-absorbing material can be obtained.

The third feature is that a heat resistance of 200 ° C. can be obtained by using a polyester raw material for the face material and the base material, or by applying a thermosetting resin such as a phenol resin to the base material and performing a heat treatment.
A fourth feature is that a self-extinguishing flame retardancy in a horizontal method can be obtained by applying a flame retardant resin such as phenol resin to a base material.

  The face material used in the present invention has at least one melt blown ultrafine fiber layer (M) having an average fiber diameter of 1 to 7 μm and a spunbond synthetic long fiber layer (S) having an average fiber diameter of 10 to 30 μm. Is a laminated non-woven fabric having a structure in which at least two layers are sandwiched between synthetic fiber layers. For example, there are configurations such as SMS, SMMS, and SMSMS.

  The synthetic long fiber layer has an average fiber diameter of 10 to 30 μm, preferably 12 to 20 μm, and the ultrafine fiber layer has an average fiber diameter of 1 to 7 μm, preferably 1.5 to 5 μm. When the fiber diameter of the synthetic fiber continuous fiber layer is less than 10 μm, productivity and strength are lowered. If it exceeds 30 μm, the sound absorption performance is deteriorated rather than a dense structure. When the ultrafine fiber diameter is less than 1 μm, the productivity and strength are lowered, and when it exceeds 7 μm, the dense structure is lost and the sound absorption performance is lowered.

  The thickness of the entire face material made of the laminated nonwoven fabric is preferably 0.1 to 0.5 mm, more preferably 0.15 to 0.4 mm, and particularly preferably 0.2 to 0.35 mm. If the total thickness of the face material is less than 0.1 mm, the sound absorption and adhesion to the substrate are reduced. On the other hand, if the thickness exceeds 0.5 mm, the sound absorption and adhesion can be improved. Followability is reduced.

The basis weight of the ultrafine fiber layer of the laminated nonwoven fabric is 1 to 40 g / m ² , preferably 3 to 30 g / m ² , and more preferably 5 to 25 g / m ² . The basis weight of the entire face material made of the laminated nonwoven fabric is preferably ²⁰ to 100 g / m ² , more preferably 25 to 80 g / m ² , and particularly preferably 30 to 60 g / m ² . If the basis weight of the whole face material is less than 20 g / m ² , the sound absorption and adhesion to the substrate will be reduced. On the other hand, if it exceeds 100 g / m ² , the sound absorption and adhesion can be improved. Mold followability is reduced.

The apparent density of the entire face material made of the laminated nonwoven fabric is preferably 0.05 to 0.5 g / cm ³ , more preferably 0.08 to 0.3 g / cm ³ , and particularly preferably 0.1 to 0.25 g / cm ³ . cm ³ . If the apparent density of the entire face material is less than 0.05 g / cm ³ , the change in thickness is large and friction fluff tends to occur. On the other hand, if the apparent density exceeds 0.5 g / cm ³ , it becomes dense and follows the molding process. Sex is reduced.

  The weight ratio of the ultrafine fiber layer in the entire face material is preferably 5 to 40 wt%, more preferably 7 to 35 wt%. When the weight ratio of the ultrafine fiber layer is less than 5 wt%, the sound absorbing performance is lowered. On the other hand, if it exceeds 40 wt%, the sound absorption performance can be improved, but the productivity of the face material is lowered.

  In the present invention, the laminated nonwoven fabric constituting the face material is made of polyester fiber such as polyethylene terephthalate, polybutylene terephthalate, copolymer polyester, aliphatic ester, sheath is made of polyethylene, polypropylene or copolymer polyester, and the core is polyethylene terephthalate or It consists of a polyester fiber mainly containing a polyester composite fiber such as a core-sheath structure made of polybutylene terephthalate or the like. Furthermore, a flame-retardant fiber or the like in which a phosphorus-based flame retardant is kneaded or the like can be used.

In this invention, the synthetic fiber continuous fiber layer which comprises the surface which contact | connects the base material of a face material is comprised by the fiber of 30-150 degreeC, Preferably it is 40-140 degreeC lower than another synthetic fiber continuous fiber layer. By adopting such a configuration, the low melting point fiber softens or melts at the time of adhesion to the base material and plays an adhesive role, so that the face material and the base material can be bonded. The melting point of the fibers constituting the synthetic long fiber layer constituting the surface in contact with the substrate is preferably 120 to 240 ° C, more preferably 125 to 230 ° C, and the melting points of the fibers constituting the other layers are 240 to 270 ° C. Is more preferable, and it is 245-265 degreeC.
The low melting point fiber constituting the surface in contact with the substrate is preferably a core sheath type fiber in which the sheath is composed of a low melting point polymer and the core is composed of a high melting point polymer. In the present invention, the melting point of the core sheath type fiber is preferred. Means the melting point of the polymer constituting the sheath. As such a core-sheath fiber, a composite fiber in which the core is polyethylene terephthalate and the sheath is a polyester copolymer is particularly preferable.
For the nonwoven fabric constituting the lower layer in contact with the base material, other long fibers other than the nonwoven fabric constituting the upper layer having a lower melting point of 30 to 150 ° C. than the nonwoven fabric constituting the upper layer, for example, the high melting point polyester constituting the upper layer Long fibers may be included. The content of the low melting point spunbond polyester long fiber in the lower layer is preferably 50 wt% or more, more preferably 80 wt% or more of the entire lower layer.

  For example, in the case of an SMS three-layer structure, the laminated nonwoven fabric constituting the face material used in the present invention is formed by forming a lower low-melting synthetic long fiber layer by a spunbond method, and forming the obtained lower-melting synthetic long fiber. An ultrafine fiber web is deposited on the web by a melt-blowing method that forms an intermediate layer, and a high-melting synthetic fiber web that forms an upper layer is formed thereon by a spunbond method. It can be produced by partial thermocompression bonding between rolls.

  The partial thermocompression bonding rate is preferably 3 to 35%, more preferably 5 to 30%. When the partial compression bonding rate is less than 3%, there is little bonding between fibers, and the friction strength is reduced. On the contrary, when the partial thermocompression bonding rate exceeds 35%, the bonding strength and the friction strength are increased, but the rigidity is increased, the adhesive processability with the base material is lowered, and the bending noise is generated.

  The thermocompression bonding temperature is 15 to 80 ° C., preferably 20 to 60 ° C. lower than the melting point of the high melting synthetic fiber, and the pressure between rolls is 100 to 1000 N / cm, preferably 150 to 700 N / cm. By performing the above, a laminated nonwoven fabric having excellent strength and friction strength can be obtained.

  The base material used in the present invention is mainly repellent felt made of recycled fibers such as cotton, wool, cotton and synthetic fibers, contains low melting point fibers, thermosetting resins, flame retardants, etc., and adheres to the face material. It is characterized by imparting properties, heat molding processability and flame retardancy. Particularly preferably, a repellent felt made of synthetic fiber felt which is a recycled fiber made of synthetic fiber is used.

The weight ratio of the repellent felt to the weight of the substrate is 40 to 95 wt%, preferably 45 to 90 wt%, more preferably 50 to 80 wt%. The weight ratio of the low melting point fiber is 5 to 60 wt%, preferably 10 to 55 wt%, more preferably 20 to 50 wt%.
When the repellent felt is less than 40 wt% and the low melting point fiber exceeds 60 wt%, the adhesion to the face material and the heat molding processability are improved, but the flame retardancy is lowered and the price is increased. On the other hand, when the repellent felt exceeds 95 wt% and the low melting point fiber is less than 5 wt%, the adhesion to the face material, the heat molding processability, the rigidity, and the like are lowered.

  In the present invention, the low-melting fiber used for the base material is preferably a polyester fiber, and particularly comprises a copolyester polymer having a melting point of 110 to 230 ° C, preferably 115 to 210 ° C, more preferably 120 to 200 ° C. Polyester composite fibers, copolymer polyester fibers, and the like are preferably used, and examples of polyester composite fibers include composite fibers having a core made of polyethylene terephthalate and a sheath made of a copolymer polyester polymer.

  Furthermore, for the purpose of imparting flame retardancy and rigidity of the substrate, a thermosetting resin such as a phenol resin, a flame retardant such as a guanidine phosphate derivative, a carbamine phosphate, and a phosphorus nitrogen compound are added to the weight of the anti-hair felt. 3 to 40 wt%, preferably 5 to 35 wt%, more preferably 10 to 30 wt%. If the coating amount of the flame retardant and the resin is less than 3 wt% with respect to the weight of the repellent felt, the flame retardancy and rigidity are lowered. On the other hand, if it exceeds 40 wt%, flame retardancy and rigidity can be increased, but there are problems such as an increase in price. Application of a flame retardant resin, a thermosetting resin, or the like is preferably performed using a coating method such as a spray method or a dipping method, and particularly preferably applied to a repellent felt.

The basis weight of the substrate used in the present invention is preferably 400 to 2700 g / m ² , more preferably 500 to 2500 g / m ² , and particularly preferably 600 to 2000 g / m ² . When the basis weight is less than 400 g / m ² , sound absorption and rigidity are lowered. If it exceeds 2700 g / m ² , the sound absorption and rigidity can be increased, but the weight cannot be reduced and the price is increased.

The apparent density of the substrate is preferably 0.01 to 0.3 g / cm ³ , more preferably 0.01 to 0.25 g / cm ³ , and particularly preferably 0.01 to 0.20 g / cm ³ . When the apparent density is less than 0.01 g / cm ³ , sound absorption and rigidity of the molded product are lowered. On the other hand, when the apparent density exceeds 0.3 g / cm ³ , the rigidity of the moldable product is increased, but the sound absorption is greatly reduced.

  The molded sound-absorbing material of the present invention can be obtained by heat-bonding the face material and the base material and then molding. The method for heat-bonding the face material and the base material is not particularly limited as long as the low melting point fiber component of the face material and the base material is heated to be softened or melted and used as an adhesive. For example, as a bonding method, in the production process of the base material, the face material is overlapped on the base material, and then hot air of 150 to 280 ° C. is used in the heating zone to form a conveyor net or a caterpillar conveyor belt. For example, there may be mentioned a method in which the heat treatment is performed by sandwiching the sheet material and the face material and the base material are heated and pressed to bond them.

  In particular, as the adhesion between the face material and the base material, when the thickness of the base material is large, it is difficult to heat up to the center part of the base material. The whole base material can be heated, and adhesion between the face material and the base material is preferably performed. The thickness of the substrate is preferably 30 to 70 mm, and more preferably 35 to 60 mm. If it is less than 30 mm, the sound absorption and rigidity are lowered, and if it exceeds 70 mm, the sound absorption and rigidity are increased.

  The molded sound-absorbing material of the present invention can be obtained by stacking a face material and a base material, and performing hot molding or cold molding. Examples of the heat forming method include a method in which a sheet-like material obtained by bonding a face material and a base material is formed using a mold heated to a temperature of 150 to 250 ° C, preferably 160 to 240 ° C. In thermoforming, by heating the sheet-like material, the resin is softened and molding processability is obtained, and by further heating, the curing reaction of the resin proceeds and the molded product obtains rigidity after processing. For example, it is preferably used for forming a substrate using a thermosetting resin such as a phenol resin. Further, as a cold forming method, the sheet-like material obtained by bonding the face material and the base material is heated in a hot air zone in which heat treatment can be performed using hot air at a temperature of 150 to 280 ° C, preferably 160 to 270 ° C, Then, the method of cold press-molding using the metal mold | die which can be cooled to the temperature of 5-20 degreeC is mentioned. Cold forming is preferably used when a flame retardant other than a thermosetting resin is used and many low-melting fibers are used. This is because heat is generated during the molding process, the mold is heated, and problems such as deterioration of the mold releasability of the low melting point fiber do not occur.

  The molded sound-absorbing material used for the vehicle dash silencer of the present invention is obtained by heat-bonding the face material made of the laminated nonwoven fabric and the substrate, and heat-press-molding to obtain high sound-absorbing properties even when the thickness is reduced. It has features that can. In particular, there is high sound absorption in a high frequency range of 2000 to 5000 Hz. Sound absorptivity is 40% or more as measured by the normal incidence method of JIS-A-1405. It is more preferable to show 45 to 100%, and it is particularly preferable to show 50 to 100%.

Basis weight of the formed sound-absorbing material of the present invention is 500~3000g / m ^2, preferably 550~2500g / m ^2, more preferably 600~2000g / m ^2, a thickness 2 to 30 mm, preferably 3 to 25 mm, more Preferably it is 5-20 mm. However, in order to obtain high sound absorption, a shape that increases the thickness as much as possible is preferable except for the fastener portion. Therefore, it is preferable that the thickness of the fastener portion is as thin as 2 to 5 mm and the shape of the portion with high rigidity, and the thickness of the other portion is as thick as 5 to 30 mm, preferably 8 to 25 mm.

When the basis weight is 500 g / m ² or less and the thickness is 2 mm or less, the weight can be reduced, but the sound absorption and the rigidity of the molded product are lowered. On the other hand, if the basis weight is 3000 g / m ² and the thickness exceeds 30 mm, the sound absorption and the rigidity of the molded product can be increased, but there are problems such as an increase in mounting space and an increase in price.

The molded sound-absorbing material of the present invention is used for a three-dimensional vehicle dash silencer that is heat-press molded using a concave-convex mold so that it can be easily attached to the engine room, driver's seat, etc. of each vehicle type. A molded sound absorbing material is obtained. As the molding process, the molding member composed of the face material and the base material is heated to a temperature of 180 to 220 ° C. and then press-molded with an uneven die. At this time, the end portion, which is the mounting portion of the molded sound absorbing material used in the vehicle dash silencer, has the rigidity necessary to maintain the overall shape, and is durable, flame retardant, and engine room. For example, heat resistance that does not cause changes in appearance and dimensions at 200 ° C. is required. Further, it is necessary to increase the sound absorption, and it is preferable to increase the thickness and decrease the apparent density within a range in which the shape of the molded sound absorbing material can be maintained. As described above, the thickness is 2 to 30 mm, preferably 3 to 25 mm, and more preferably 5 to 20 mm. Apparent density is preferably set to 0.02 to 0.5 g / cm ^3, more preferably 0.04~0.45g / cm ^3, particularly preferably 0.05 to 0.4 g / cm ^3. When the thickness is less than 2 mm and the apparent density exceeds 0.5 g / cm ³ , the rigidity becomes high, but the sound absorption is extremely lowered. On the other hand, if the thickness exceeds 30 mm and the apparent density is less than 0.02 g / cm ³ , the sound absorbing property can be increased, but the rigidity is lowered and the shape-retaining property of the molded sound absorbing material is lowered.

EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these Examples. Each characteristic value was measured by the following method.
(1) Weight per unit area (g / m ² ): Measured according to JIS-L-1913.
(2) Average fiber diameter (μm): 500 times magnified photograph was taken with a microscope, 10 fiber diameters were measured, and the average value was taken as the average fiber diameter.

(3) Thickness (mm): Conforms to JIS-L-1913-B method. The thickness of the pressure with a load of 0.02 kPa was measured at three locations, and the average value was shown. However, the thickness of the face material was measured at a load of 20 kPa.
(4) Apparent density (g / cm ³ ): Calculated from (weight per unit area) / (thickness) to determine the weight per unit volume.
(5) Sound absorption (%): According to JIS-A-1405, a frequency of 2000 to 5000 Hz was measured with a vertical incidence measuring machine.

(6) Flame retardancy: Combustion test for automobile interior materials in accordance with JIS-D-1201.
A test piece (350 mm × 100 m) is held horizontally, a 38 mm flame is indirectly flamed for 15 seconds, and a judgment is made based on the burning speed for 254 mm between the A and B mark lines. A passing rate between the marked lines of 100 mm / min or less, a burning distance of 50 mm or less, or a burning time of 60 seconds or less is regarded as acceptable (◯).

(7) Heat resistance: A heater is placed in a box-type heat insulation box using a heat insulating material to which a 300 mm square test piece is attached at the top, and the test piece is attached at the top, so that the surface temperature of the test piece reaches 200 ° C. The surface condition after being left for 1 hour was observed and judged according to the following criteria.
○: No melting, scoring, swelling, or discoloration.
Δ: Slightly less melting, scorching, blistering, or discoloration.
X: Melting, scorching, swelling, and discoloration are severe.

(8) Thermal insulation: Measured according to the description in Example 9 described later.
(9) Molding workability: The face material and the base material were overlapped, and the joining process and the molding process were performed under the conditions described in Example 1, and evaluated according to the following criteria.
◯: Following the uneven shape of the molding die.
(Triangle | delta): Following the uneven | corrugated shape of a shaping | molding die, there exists partial floating.
X: The float is conspicuous without following the uneven shape of the molding die.

[Example 1]
The laminated nonwoven fabric used for the face material was produced by the following procedure. Using a spinneret for polyethylene terephthalate, a long fiber web A made of polyethylene terephthalate (melting point: 263 ° C.) was formed on a collection net at a spinning temperature of 300 ° C. by a spunbond method, and the resulting long fiber web A was subsequently obtained. From a polyethylene terephthalate (melting point: 265 ° C.) using a melt-blowing nozzle on a basis weight of 10 g / m ² and an average fiber diameter of 14 μm at a spinning temperature of 300 ° C., heated air of 320 ° C. and 1000 Nm ² / hr. The resulting yarn was ejected to form an ultrafine fiber web B (weighing 5 g / m ² , average fiber diameter 3 μm). Further, on a very fine fiber web B, a two-component spinneret is used, and a long-sheath web C having a core-sheath structure in which a sheath component is a copolymer polyester (melting point 210 ° C.) and a core component is polyethylene terephthalate (melting point 265 ° C.). A basis weight of 10 g / m ² and an average fiber diameter of 18 μm) were laminated by a spunbond method. The resulting laminated web was partially thermocompression bonded using a pair of embossing rolls / flat rolls at a temperature of 230 ° C./165° C. and a linear pressure of 300 N / cm, with a basis weight of 25 g / m ² and an average apparent density. Of 0.15 g / cm ³ , a thickness of 0.17 mm, and a surface material made of a laminated nonwoven fabric having a partial thermocompression bonding rate of 15%.

As a base material, a low-melting fiber having a fiber diameter of 16 μm (a core is polyethylene terephthalate, a sheath has a melting point of 165, and a flame-retardant repellent felt obtained by adhering 10 wt% of a flame retardant made of a guanidine phosphate derivative to synthetic fiber recycled short fibers. A base material made of a non-woven fabric having a basis weight of 1000 g / m ² and a thickness of 40 mm was obtained using a mixed cotton mixed with a polyester copolymer core-sheath fiber at a temperature of 70 ° C. (anti-wool felt 70 wt%, low melting point fiber 30 wt% % Mixed cotton ratio). Next, the low melting point fiber surface of the face material was bonded to the base material. As the bonding process, the face material and the base material are overlapped, sandwiched between the conveyor belts, heated and pressurized in an atmosphere of 220 ° C., and joined together (sucking from the lower part of the conveyor belt to heat the whole) ). Next, it was preheated to a temperature of 210 ° C. and cold press-molded with a dash silencer mold to obtain a molded sound absorbing material for use in the dash silencer for vehicles of the present invention having a basis weight of 1025 g / m ² and a thickness of 25 mm. The characteristics are shown in Table 1.

[Example 2]
The laminated nonwoven fabric used for the face material was produced by the following procedure. Using a spinneret for polyethylene terephthalate, a long fiber web A made of polyethylene terephthalate (melting point: 263 ° C.) was formed on a collection net at a spinning temperature of 300 ° C. by a spunbond method, and the resulting long fiber web A was subsequently obtained. It is made of polyethylene terephthalate (melting point 260 ° C.) using a melt blow nozzle on a basis weight of 15 g / m ² and an average fiber diameter of 14 μm at a spinning temperature of 300 ° C., heated air of 320 ° C. and 1000 Nm ² / hr. The yarn was ejected to form an ultrafine fiber web B (weighing 10 g / m ² , average fiber diameter 3 μm). Further, on a very fine fiber web B, a two-component spinneret is used, and a long-sheath web C having a core-sheath structure in which a sheath component is a copolymer polyester (melting point 210 ° C.) and a core component is polyethylene terephthalate (melting point 265 ° C.). A basis weight of 15 g / m ² and an average fiber diameter of 18 μm) were laminated by a spunbond method. The obtained laminated web was partially thermocompression bonded using a pair of embossing rolls / flat rolls under the conditions of a temperature of 230 ° C./165° C. and a linear pressure of 300 N / cm, a basis weight of 40 g / m ² , and an average apparent density. Of 0.17 g / cm ³ , a thickness of 0.24 mm, and a partial thermocompression bonding rate of 15%, a face material made of a laminated nonwoven fabric was obtained.
The obtained face material and the same base material as in Example 1 were bonded in the same manner as in Example 1, molded using the same mold as in Example 1, with a basis weight of 1040 g / m ² and a thickness of 25 mm. The molded sound absorbing material used for the dash silencer for vehicles of the present invention was obtained. The characteristics are shown in Table 1.

[Example 3]
Using the same base material and face sheet adhesive sheet as in Example 2, a molded sound-absorbing material used for a vehicle dash silencer having a basis weight of 1040 g / m ² and a thickness of 15 mm was obtained using another mold. Are listed in Table 1.

[Example 4]
A molded sound-absorbing material used for a vehicle dash silencer having a basis weight of 1040 g / m ² and a thickness of 10 mm was obtained using another mold, using the same base material and face sheet adhesive sheet as in Example 2. The characteristics are shown in Table 1.

[Example 5]
A molded sound-absorbing material used for a vehicle dash silencer having a basis weight of 1040 g / m ² and a thickness of 5 mm was obtained using another base and an adhesive sheet of a base material and a face material similar to Example 2. The characteristics are shown in Table 1.

[Example 6]
The base material was produced in the following procedure. 20 wt% of a solvent-based thermosetting phenol resin was applied to synthetic fiber recycled short fibers to obtain a repellent felt impregnated with the phenol resin. A mixed cotton obtained by mixing low-melting fiber having a fiber diameter of 16 μm (core is polyethylene terephthalate, sheath is a polyester copolymer core-sheath type fiber having a melting point of 165 ° C.) into the obtained bristle felt, and has a basis weight of 600 g / m. ^{2. A} base material made of a nonwoven fabric having a thickness of 30 mm was obtained (a mixed cotton ratio of 60 wt% of repellent felt and 40 wt% of low melting point fibers). Subsequently, the obtained base material and the face material similar to Example 1 were adhered. As the bonding process, as in Example 1, the face material and the base material were overlapped and sandwiched between conveyor belts, and bonded by performing heat treatment and heat treatment in an atmosphere at a temperature of 220 ° C. Next, heat-press molding was performed with a heating mold of a dash silencer at a temperature of 210 ° C. to obtain a molded sound absorbing material used for the vehicle dash silencer of the present invention having a basis weight of 625 g / m ² and a thickness of 20 mm. The characteristics are shown in Table 1.

[Example 7]
The laminated nonwoven fabric used for the face material was prepared by the following procedure. Using a spinneret for polyethylene terephthalate, a long fiber web A made of polyethylene terephthalate (melting point: 263 ° C.) was formed on a collection net at a spinning temperature of 300 ° C. by a spunbond method, and the resulting long fiber web A was subsequently obtained. Polyethylene terephthalate (melting point 260 ° C.) using a melt blow nozzle on a basis weight (weight 35 g / m ² , average fiber diameter 14 μm), spinning temperature 300 ° C., heated air 320 ° C. and 1000 Nm ² / hr. Were spun out to form an ultrafine fiber web B (weighing 10 g / m ² , average fiber diameter 3 μm). Further, on a very fine fiber web B, a two-component spinneret is used, and a long-sheath web C having a core-sheath structure in which a sheath component is a copolymer polyester (melting point 210 ° C.) and a core component is polyethylene terephthalate (melting point 265 ° C.). A basis weight of 35 g / m ² and an average fiber diameter of 18 μm) were laminated by a spunbond method. The obtained laminated web was partially thermocompression bonded using a pair of embossing rolls / flat rolls at a temperature of 230 ° C./165° C. and a linear pressure of 300 N / cm, with a basis weight of 80 g / m ² and an average apparent density. Of 0.25 g / cm ³ , a thickness of 0.37 mm, and a partial thermocompression bonding rate of 15%, a face material made of a laminated nonwoven fabric was obtained. The obtained face material and the same base material as in Example 6 were bonded in the same manner as in Example 6. Next, the obtained adhesive sheet was subjected to hot press molding using a heating mold of a dash silencer having a temperature of 210 ° C. Thus, a molded sound absorbing member for use in the vehicle dash silencer of the present invention having a basis weight of 680 g / m ² and a thickness of 10 mm was obtained. The characteristics are shown in Table 1.

[Example 8]
The base material was produced in the following procedure. 20 wt% of a solvent-based thermosetting phenol resin was applied to synthetic fiber recycled short fibers to obtain a repellent felt impregnated with the phenol resin. Using the blended cotton obtained by mixing low-melting fiber (fiber core is polyethylene terephthalate, sheath is a polyester copolymer core-sheath type fiber having a melting point of 165 ° C.) having a fiber diameter of 16 μm, and the basis weight is 1200 g / m. ^{2. A} base material made of a nonwoven fabric having a thickness of 50 mm was obtained (a mixed cotton ratio of 80% by weight of repellent felt and 20% by weight of low-melting fiber). Subsequently, the obtained base material and the face material similar to Example 1 were adhered. As the bonding process, as in Example 1, the face material and the base material were overlapped and sandwiched between conveyor belts, and bonded by performing heat treatment and heat treatment in an atmosphere at a temperature of 220 ° C. Next, heat-press molding was performed with a heating mold of a dash silencer at a temperature of 210 ° C. to obtain a molded sound absorbing material for use in the vehicle dash silencer of the present invention having a basis weight of 1225 g / m ² and a thickness of 20 mm. The characteristics are shown in Table 1.
As is apparent from the description in Table 1, the molded sound absorbing material used in the vehicle dash silencer of Examples 1 to 8 of the present invention is excellent in molding processability and excellent in sound absorbing property, flame retardancy, and heat resistance. It was.

[Example 9]
The heat insulating properties of the molded sound absorbing materials of Examples 6, 7, and 8 were measured. A test piece is cut into a square of 300 mm x 300 mm, and a heater that can be heated to a temperature of 200 ° C is placed in an insulating box in which a 300 mm square test piece can be set on top, and the temperature inside the test piece is controlled at 160 ° C. The heat insulation rate was measured by measuring the outer surface temperature and the outside air temperature. As a result of obtaining the heat insulation rate by the following calculation formula, the heat insulation rate of Example 6 was 78%, the heat insulation rate of Example 7 was 67%, and the heat insulation rate of Example 8 was 86%. For example, in Example 8, the outside air temperature was 28 ° C., the inside surface temperature was 160 ° C., and the outside surface temperature was 46 ° C.
Thermal insulation rate (%) = {1-{(outside temperature−outside temperature) / (inside temperature−outside temperature)} × 100

[Comparative Example 1]
When only the base material of Example 6 was molded in the same manner as Example 7, a molded sound absorbing material having a basis weight of 600 g / m ² and a thickness of 5 mm was obtained. The characteristics are shown in Table 1.

[Comparative Example 2]
When only the base material of Example 1 was molded in the same manner as in Example 5, a molded sound-absorbing material having a basis weight of 1000 g / m ² and a thickness of 5 mm was obtained. The characteristics are shown in Table 1.

[Comparative Example 3]
When only the base material of Example 8 was molded in the same manner as in Example 8, a molded sound-absorbing material having a basis weight of 1000 g / m ² and a thickness of 5 mm was obtained. The characteristics are shown in Table 1.

[Comparative Example 4]
Using a spinneret for polyethylene terephthalate, a long fiber web made of polyethylene terephthalate (melting point: 263 ° C.) at a spinning temperature of 300 ° C. was formed on a collection net by a spunbond method. The obtained long fiber web (weight per unit area 25 g / m ² , average fiber diameter 14 μm) was partially heated using a pair of embossing rolls / flat rolls at a temperature of 230 ° C./220° C. and a linear pressure of 300 N / cm. A face material made of a long-fiber nonwoven fabric having a basis weight of 25 g / m ² , an average apparent density of 0.25 g / cm ³ , a thickness of 0.24 mm, and a partial thermocompression bonding rate of 15% was obtained. The obtained face material and the same base material as in Example 6 were bonded using polyethylene powder, and then molded in the same manner as in Example 8. The molded sound absorbing material had a basis weight of 1000 g / m ² and a thickness of 5 mm. Got. The characteristics are shown in Table 1.
As is apparent from Table 1, the sound absorbing materials of Comparative Examples 1 to 4 did not obtain the desired sound absorbing properties.

  The molded sound-absorbing material of the present invention is excellent in bondability between the low melting point layer of the face material and the base material, and uses a laminated nonwoven fabric including an ultrafine fiber layer, so that excellent sound-absorbing property is obtained. As a result, it is excellent in conformability of the concave and convex shape, molding processability, sound absorption after the molding process, shape retaining property, light weight and the like. Therefore, it is suitably used as a sound absorbing material for various automobile members, particularly a molded sound absorbing material used for a dash silencer for vehicles.

Claims (7)

A sound-absorbing material for use in a vehicle dash silencer in which a face material made of a laminated nonwoven fabric of polyester fibers and a base material mainly made of anti-felt felt are bonded, wherein the face material has a fiber diameter of 10 to 30 μm. At least three layers comprising an upper layer made of a polyester long fiber, an intermediate layer made of a melt blown polyester ultrafine fiber having a fiber diameter of 1 to 7 μm, and a lower layer containing a spunbond polyester long fiber having a melting point of 30 to 150 ° C. lower than the upper layer Is a laminated nonwoven fabric thermocompression bonded at a partial thermocompression rate of 3 to 35%, and the base material is a nonwoven fabric containing 40 to 95 wt% of repellent felt and 5 to 60 wt% of low-melting polyester fiber, The lower layer of the material is bonded to the substrate, the thickness is 2-30 mm, the mass is 500-3000 g / m ² , and according to JIS-A-1405 A molded sound absorbing material used for a vehicle dash silencer having a sound absorption of 40% or more at a frequency of 2000 to 5000 Hz according to the normal incidence method. ^2. The molded sound absorbing material according to claim 1, wherein the face material has a thickness of 0.1 to 0.5 mm and a basis weight of 20 to 100 g / m ² .   The molded sound-absorbing material according to claim 1 or 2, wherein a mass ratio of the melt blown polyester-based ultrafine fibers of the face material is 5 to 40 wt%.   The molded sound-absorbing material according to any one of claims 1 to 3, wherein the lower layer of the face material is a composite fiber of which the core is polyethylene terephthalate and the sheath is a polyester-based copolymer.   The molded sound-absorbing material according to any one of claims 1 to 4, wherein the base material contains 3 to 40 wt% of a flame retardant with respect to the weight of the repellent felt.   The molded sound-absorbing material according to claim 5, wherein the flame retardant is contained in the repellent felt.   The molded sound absorbing material according to claim 5 or 6, wherein the flame retardant is a phenol resin flame retardant.