JP5055856B2 - Production method of sound absorbing material - Google Patents

Description

The present invention relates to a method of manufacturing a suction sound material.

Generally, in a vehicle such as an automobile, various soundproofing bodies such as a floor carpet and a floor mat are provided in order to prevent noise outside the vehicle interior from propagating into the vehicle interior.
Among the soundproofing bodies, there is a sound insulating material that uses a sound insulating base material such as a thermoplastic resin to insulate noise transmitted from a floor panel or the like in order to insulate noise outside the passenger compartment. In such a sound insulating material, the vibration speed of the propagating sound is generally defined by the mass (surface density) of the sound insulating material. Therefore, the sound insulating material increases the mass of the sound insulating base material, thereby reducing the vibration speed of the propagating sound and improving the sound insulating effect.

  However, once the sound enters the vehicle compartment through a window or the like, it is reflected into the vehicle when it hits a sound insulating base material having a large mass. As a result, the sound-insulating base material having a large mass causes a problem that the sound entering the vehicle interior is subjected to multiple reflections in the vehicle interior and the quietness of the vehicle interior is impaired. In addition, the sound insulating base material having a large mass causes an increase in the vehicle weight by an amount corresponding to the increase in the weight, thereby reducing the vehicle fuel consumption.

  On the other hand, in the soundproof body, there is a sound absorbing material that absorbs sound entering the vehicle interior using a sound absorbing base material such as urethane in order to absorb noise. The sound absorbing material (fiber mat for automobiles) of Patent Document 1 has a foam sound absorbing material such as polyurethane on the back side of a skin material such as a woven fabric. In addition, the foamed sound absorbing material contains an additive that increases the amount of dipole moment of the base resin material.

As a result, the automobile fiber mat converts the sound hitting the foamed sound absorbing material into air vibrations of the air bubbles in the foam, and converts the sound energy into heat energy (absorbs sound) by viscous friction of the air on the surface of the air bubbles. ). Moreover, the foamed sound absorbing material converts sound energy into the displacement energy of the dipole of the base resin material to increase the sound absorbing action. Therefore, it is possible to reduce the weight of the automobile fiber mat and improve the soundproofing property.
JP 2005-289121 A

  However, the automobile fiber mat of Patent Document 1 has a backing on the back surface of the skin material, and the foamed sound absorbing material is lined on the back surface of the backing material. And this backing is formed with the thermoplastic resin which does not have a sound-absorbing performance, Furthermore, no consideration is made regarding the air permeability.

  Therefore, although the fiber mat for automobiles of Patent Document 1 smoothly absorbs noise from the floor panel side (back side) by the foamed sound absorbing material, it makes it difficult to transmit noise from the vehicle interior (front side) to the foamed sound absorbing material. Yes. As a result, the fiber mat for automobiles of Patent Document 1 inhibits the sound absorbing action of the foamed sound absorbing material and the sound absorbing action of the floor carpet disposed on the back side of the foamed sound absorbing material with respect to noise from the vehicle interior (front side). Had a problem.

An object of the present invention has been made to solve the above problems, while achieving weight reduction, it is to provide a manufacturing method of the intake sound material with improved sound absorption.

  According to this sound absorbing material, the sound hitting the skin material is more reliably transmitted to the inside of the foamed layer by the low foaming magnification layer. And the sound propagated inward of the foam layer is more reliably attenuated by the high foam ratio layer.

The method for producing a sound-absorbing material of the present invention includes a coating step of coating a foamed resin material on the back surface of a skin material, and heating the surface side of the skin material at a predetermined temperature while the foamed resin material is coated. Heating the back side of the material at a temperature higher than the predetermined temperature to form a foam layer that adheres to the back side of the skin material, and increasing the foaming ratio of the foam layer in the direction from the skin material toward the foam layer A foaming step , wherein the foaming step heats the skin material side at a predetermined temperature and simultaneously heats the back surface side of the skin material at a temperature higher than the predetermined temperature .

  According to the method for producing a sound-absorbing material of the present invention, when forming a foam layer bonded to a skin material, the foaming ratio of the foam layer can be easily increased in the direction from the skin material to the foam layer. Therefore, the sound hitting the skin material is propagated and confined to the inside of the foam layer having a low foaming ratio, that is, a high density (low air flow rate). And the sound which propagated inward of the foaming layer and was again suppressed to the passenger compartment side attenuates at a high foaming ratio, that is, the inside of the foaming layer having a low density. Therefore, a sound absorbing material with improved sound absorbing properties can be manufactured.

The method for producing a sound-absorbing material of the present invention includes a coating step in which a foamed resin material is applied to one of a skin material and a substrate, and a bonding process in which the skin material and the substrate are bonded via the foamed resin material. In a state where the skin material and the base material are bonded to each other, the skin material side and the base material side are heated at a predetermined temperature and a temperature higher than the predetermined temperature, respectively, to the skin material and the base material. A foaming step of forming a foaming layer to be bonded and increasing a foaming ratio of the foaming layer from the skin material side toward the base material side , wherein the foaming step heats the skin material side at a predetermined temperature. At the same time, the base material side is heated at a temperature higher than the predetermined temperature .

  According to the method for producing a sound absorbing material of the present invention, when forming a foam layer that adheres the skin material and the substrate, the foaming ratio of the foam layer can be easily increased in the direction from the skin material to the substrate. it can. Therefore, the sound hitting the skin material is propagated and confined to the inside of the foam layer having a low foaming ratio, that is, a high density (low air flow rate). And the sound which propagated inward of the foaming layer and was again suppressed to the passenger compartment side attenuates at a high foaming ratio, that is, the inside of the foaming layer having a low density. Therefore, a sound absorbing material with improved sound absorbing properties can be manufactured.

  According to this method for producing a sound-absorbing material, it is possible to form a foamed layer having a foaming ratio that increases from the skin material side toward the base material side by one heating and foaming. Therefore, the productivity of the sound absorbing material can be improved.

  Hereinafter, a vehicle floor mat 1 as a sound absorbing material according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing a vehicle floor mat 1. FIG. 2 is an example in which the main part of the vehicle floor mat 1 is imaged with a scanning electron microscope (SEM).

  In FIG. 1, a vehicle floor mat 1 is provided with a base material 2. The base material 2 is a known sound-absorbing material that absorbs sound hitting the back side (the lower side in FIG. 1) of the vehicle floor mat 1, and for example, a non-woven fabric or foam having air permeability can be used.

  A backing layer 3 as a foam layer is formed on the front side of the substrate 2 (upper side in FIG. 1). The backing layer 3 is formed of a foamed resin material that can be heat-bonded to the surface of the substrate 2. The backing layer 3 has an open cell structure that adheres to the surface of the substrate 2 (upper surface in FIG. 1), and is permeable to air. The backing layer 3 may contain closed cells in the open cell structure. The open cells contained in the backing layer 3 improve the sound absorbing effect of the backing layer 3. On the other hand, the closed cells included in the backing layer 3 improve the sound insulation effect of the backing layer 3.

  The backing layer 3 increases the expansion ratio along the direction from the front side to the back side (downward in FIG. 1). Specifically, as shown in FIG. 2, as the backing layer 3 approaches the back side, the number of open cells is increased and the size thereof is reduced to reduce the thickness of the walls constituting the open cells. To do. On the other hand, as the backing layer 3 approaches the front side, the number of open cells is reduced and the size thereof is increased to increase the thickness of the walls constituting the open cells. That is, the backing layer 3 decreases the density along the direction from the front side to the back side to increase the air flow rate.

Then, the sound hitting the surface of the backing layer 3 propagates while being attenuated inward of the backing layer 3 through the open-side bubbles on the front side. The sound that has once propagated to the inside of the backing layer 3 is easily confined inside the backing layer 3 by the amount of airflow on the front side being small. The sound that is confined inside the backing layer 3 and is prevented from being released to the passenger compartment side again is dispersed into a plurality of open cells and is more effectively attenuated by the increase in the foaming ratio on the back side. .

  If the foaming ratio of the backing layer 3 becomes excessively low, the air flow rate becomes too small and the sound propagation property is impaired. In addition, the number of open cells becomes too small, and the dispersibility of the propagated sound is impaired. On the other hand, if the foaming ratio of the backing layer 3 becomes excessively high, the amount of air flow increases so that the sound propagated inward of the backing layer 3 cannot be confined. Therefore, when reducing vehicle noise, it is preferable that the foaming ratio of the backing layer 3 is 1.5 to 10 times.

  The backing layer 3 is not limited to a single layer structure, and may be a multilayer structure having a plurality of layers. For example, as shown in FIG. 2, it is bonded to the surface of the base material 2 and has a high expansion ratio layer 3H having an expansion ratio of 3.5 to 8.0 and an upper layer of the high expansion ratio layer 3H. A two-layer configuration including a low expansion ratio layer 3L having a magnification of 1.5 to 4.0 times may be used.

When the air permeability of the backing layer 3 becomes excessively low, the sound hitting the surface of the backing layer 3 is reflected. On the other hand, when the amount of air flow becomes excessively large, the backing layer 3 transmits the sound hitting the surface of the backing layer 3 with almost no attenuation. Therefore, when reducing the vehicle noise, preferably the air permeability of the backing layer 3 to 5 cc / cm ² / sec ~20cc / cm ² / sec. The air permeability of the backing layer 3 can be controlled by adding a filler (such as an inorganic filler such as calcium carbonate, calcium hydroxide, or silica) to the backing layer 3 and adjusting the formulation of the surfactant.

  The foamed resin material of the backing layer 3 is a known thermosetting or thermoplastic resin material, which is a resin material that is physically agitated and forcedly foamed (foamed), or a resin material containing a foaming agent Can be used. Examples of the resin material that can be used include olefins such as polyethylene and polypropylene, styrenes such as general-purpose polystyrene and ABS resin, acrylic resins, and polyurethane. As the foaming agent, a chemical foaming agent or a physical foaming agent can be used. Examples of the chemical foaming agent include a thermal decomposition type foaming agent that decomposes to generate nitrogen gas, and a thermal decomposition type inorganic foaming agent that decomposes to generate carbon dioxide gas. Examples of the physical foaming agent include water and carbon dioxide gas. The stirring conditions and the type of the foaming agent are appropriately selected based on the foaming ratio of the backing layer 3 and the heating / foaming conditions of the foamed resin material.

  In FIG. 1, a skin material 4 bonded by the backing layer 3 is provided on the front side of the backing layer 3 (upper side in FIG. 2). The skin material 4 is a carpet in which pile fibers 4b are woven into a base fabric 4a, but is not limited thereto, and may be a nonwoven fabric, for example. The skin material 4 has a breathability in order to use the sound absorbing action of the backing layer 3 and may be any material that can be heat bonded to the backing layer 3.

Next, a method for manufacturing the vehicle floor mat 1 configured as described above will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining the vehicle floor mat manufacturing system 10.
In FIG. 3, the vehicle floor mat manufacturing system 10 includes a skin material supply roller 11 and a support 12. The skin material supply roller 11 feeds the wound skin material 4 to the support 12 in a reversed state (the back surface of the skin material 4 is the upper side in FIG. 3).

Above the support 12, a foamed resin supply device 13, a coating roller 14, a base material supply roller 15, and a pressure roller 16 are provided.
The foamed resin supply device 13 supplies the foamed resin to the back surface (upper surface in FIG. 3) of the skin material 4 fed to the support base 12. The application roller 14 spreads the foamed resin material supplied to the back surface of the skin material 4 over the entire back surface. Then, the foamed resin material is uniformly applied to the entire back surface of the skin material 4 by the foamed resin supply device 13 and the application roller 14 (application process is performed).

  The base material supply roller 15 feeds the wound base material 2 to the support base 12 with the front and back being reversed (the surface of the base material 2 is the lower side in FIG. 3). The pressing roller 16 presses the surface (the lower surface in FIG. 3) of the fed base material 2 against the foamed resin of the skin material 4. Then, the base material 2 and the skin material 4 are bonded with a foamed resin material by the base material supply roller 15 and the pressing roller 16 (a bonding process is performed).

  The vehicle floor mat manufacturing system 10 includes a drying furnace 17. The drying furnace 17 is fed with the skin material 4 and the base material 2 in a state of being bonded together with a foamed resin material. The drying furnace 17 is provided with a high temperature heating device 17H and a low temperature heating device 17L. The high temperature heating device 17H is disposed so as to face the substrate 2 to be fed. The low-temperature heating device 17L is disposed so as to face the skin material 4 to be fed. The high temperature heating device 17H and the low temperature heating device 17L blow high temperature hot air and low temperature hot air to the base material 2 and the skin material 4 which face each other.

  The low-temperature heating device 17L heats (drys) the foamed resin material on the skin material 4 side at a predetermined temperature (for example, a low temperature of 100 ° C. to 140 ° C.) to form a part of the backing layer 3 at a low foaming ratio. Then, the skin material 4 and the backing layer 3 are bonded. The high-temperature heating device 17H heats (drys) the foamed resin material on the substrate 2 side at a temperature higher than the predetermined temperature (for example, a high temperature of 140 ° C. to 200 ° C.), and highly foams part of the backing layer 3. The base material 2 and the backing layer 3 are bonded at a magnification (performing a foaming process).

As a result, the base material 2 and the skin material 4 are adhered by the backing layer 3, and the foaming ratio of the backing layer 3 is increased along the direction from the skin material 4 toward the base material 2.
The drying furnace 17 is configured to simultaneously perform the high temperature heating of the high temperature heating device 17H and the low temperature heating of the low temperature heating device 17L, but is not limited thereto, and may be configured to perform the high temperature heating and the low temperature heating at different timings. Good. According to this, the freedom degree of the drying time by high temperature heating and the drying time by low temperature heating can be expanded, and the freedom degree of foaming magnification can be expanded. Example 1
Next, the effects of the sound absorbing material of the present invention will be described with reference to examples and comparative examples.

  First, the normal incident sound absorption coefficient of only the backing layer 3 will be described with reference to Table 1 and FIG. Table 1 shows the expansion ratio, thickness, and basis weight of Example 1 and Comparative Examples 1 to 3. FIG. 4 shows the normal incidence sound absorption coefficient of Example 1 and Comparative Examples 1-3.

Example 1 was obtained using a foamed acrylic resin as the foamed resin material, calcium carbonate as the filler, and a low temperature heating temperature of 110 ° C. and a high temperature heating temperature of 140 ° C.
As shown in Table 1, Example 1 has a low foaming ratio layer 3L with a foaming ratio of 3 times and a thickness of 5 t (t: arbitrary unit), and a high foaming with a foaming ratio of 6 times and a thickness of 5 t. It has a magnification layer 3H. The total basis weight of Example 1 is 830 g / m ² . And the low foaming magnification layer 3L was arrange | positioned at the sound source side, and the normal incidence sound absorption coefficient of Example 1 was measured using the acoustic tube method (in-tube method) (refer the continuous line of FIG. 4). At this time, the normal incident sound absorption coefficient was measured in the wave number region where the 1/3 octave band center frequency was 100 to 4000 Hz.
(Comparative Example 1)
Comparative Example as in Example 1, using foamed acrylic resin as foamed resin material, calcium carbonate as filler, under conditions of low temperature heating temperature of 110 ° C. and high temperature heating temperature of 140 ° C. 1 was obtained.

As shown in Table 1, Comparative Example 1, like Example 1, has a low expansion ratio layer 3L with a foaming ratio of 3 times and a thickness of 5 t, and a high expansion ratio with a foaming ratio of 6 times and a thickness of 5 t. It has layer 3H. The total basis weight of Comparative Example 1 is 830 g / m ² as in Example 1. Then, the high expansion ratio layer 3H was arranged on the sound source side, and the normal incident sound absorption coefficient of Comparative Example 1 was measured using the acoustic tube method (in-tube method) as in Example 1 (see the one-dot chain line in FIG. 4).
(Comparative Example 2)
Comparative Example 2 was obtained under the condition of using foamed acrylic resin as foamed resin material, calcium carbonate as filler, and heating and foaming temperature of 110 ° C.

As shown in Table 1, Comparative Example 2 has a foaming ratio of 3 times in the full width in the thickness direction. Comparative Example 2 has a thickness of 10 t and a total basis weight of 1100 g / m ² . And the normal incidence sound absorption coefficient of the comparative example 2 was measured using the acoustic tube method (in-tube method) like Example 1 (refer the broken line of FIG. 4). (Comparative Example 3)
Comparative Example 3 was obtained under the conditions of using foamed acrylic resin as foamed resin material, calcium carbonate as filler, and heating and foaming temperature of 140 ° C.

As shown in Table 1, Comparative Example 3 has a foaming ratio of 6 times over the entire width in the thickness direction. Comparative Example 3 has a thickness of 10 t and a total basis weight of 560 g / m ² . Then, as in Example 1, the normal incident sound absorption coefficient of Comparative Example 3 was measured using the acoustic tube method (in-tube method) (see the two-dot chain line in FIG. 4).

図４の結果から、実施例１は、計測周波数領域の略全範囲において、比較例１〜３よりも高い垂直入射吸音率を有することが分かる。そのため、バッキング層３は、音源から遠ざかる方向に向かって発泡倍率を増加させることにより、吸音性の向上を図ることができる。

From the result of FIG. 4, it can be seen that Example 1 has a higher normal incident sound absorption rate than Comparative Examples 1 to 3 in substantially the entire measurement frequency region. Therefore, the backing layer 3 can improve sound absorption by increasing the expansion ratio in the direction away from the sound source.

  In addition, as shown in FIG. 4, Example 1 has a small increase in the normal incident sound absorption coefficient as compared with Comparative Example 2, but as shown in Table 1, the total basis weight is increased by the amount by which the expansion ratio is increased. Can be reduced. Therefore, the weight of the backing layer 3 can be reduced.

  Moreover, the frequency dependence of the sound absorption coefficient can be controlled by controlling the expansion ratio. Therefore, the backing layer 3 according to the design change of the vehicle floor mat 1 can be appropriately selected.

Next, the reverberation room method sound absorption coefficient of the vehicle floor mat 1 having the backing layer 3 will be described with reference to Table 2 and FIG. Table 2 shows the basis weight of Example 2, Comparative Example 4 and Comparative Example 5. FIG. 5 shows the reverberation chamber method sound absorption rate of Example 2, Comparative Example 4 and Comparative Example 5.
(Example 2)
As shown in Table 2, a polypropylene tufted carpet having a basis weight of 800 g / m ² was used for the skin material 4, and a polyester needle punched nonwoven fabric having a basis weight of 300 g / m ² was used for the base material 2. Further, using a foamed acrylic resin as foamed resin material, using calcium carbonate as a filler, forming a backing layer 3 under conditions where the heating temperature on the low temperature side is 110 ° C. and the heating temperature on the high temperature side is 140 ° C., Example 2 was obtained.

Example 2 has a low foaming ratio layer 3L that is bonded to the skin material 4 and has a foaming ratio of 3 times, and a high foaming ratio layer 3H that is bonded to the substrate 2 and has a foaming ratio of 6 times. The backing layer 3 of Example 2 has a basis weight of 500 g / m ² . And the reverberation room method sound absorption rate of Example 2 was measured using the reverberation room method. At this time, the normal incident sound absorption coefficient was measured in a wave number region where the 1/3 octave band center frequency was 100 to 6300 Hz (see the solid line in FIG. 5).
(Comparative Example 4)
As in Example 2, a polypropylene tufted carpet having a basis weight of 800 g / m ² was used for the skin material 4, and a polyester needle punched nonwoven fabric having a basis weight of 300 g / m ² was used for the base material 2. Further, using a foamed natural rubber and styrene butadiene rubber copolymer, using calcium carbonate as a filler, forming a backing layer 3 under a heating temperature of 140 ° C. Obtained.

The backing layer 3 of Comparative Example 4 has a foaming ratio of 3 times over the entire width in the thickness direction. The backing layer 3 of Comparative Example 2 has a basis weight of 600 g / m ² . And the reverberation room method sound absorption rate of the comparative example 4 was measured using the reverberation room method similarly to Example 2 (refer the dashed-dotted line of FIG. 5).
(Comparative Example 5)
As in Example 2, a polypropylene tufted carpet having a basis weight of 800 g / m ² was used for the skin material 4, and a polyester needle punched nonwoven fabric having a basis weight of 300 g / m ² was used for the base material 2. And the backing layer 3 of the polyethylene porous sintered compact was formed under the conditions whose heating temperature is 140 degreeC using polyethylene powder, and the comparative example 5 was obtained.

The backing layer 3 of Comparative Example 5 has a basis weight of 350 g / m ² . And the sound absorption rate of the comparative example 5 was measured similarly to Example 2 using the reverberation chamber method (refer the broken line of FIG. 5).

図５の結果から、実施例２は、計測周波数領域の略全範囲において、比較例４、比較例５よりも高い残響音法吸音率を有することが分かる。そのため、車両用フロアカーペットは、表皮材４から基材２に向かう方向に沿って発泡倍率を増加させることにより、吸音性の向上を図ることができる。

From the results of FIG. 5, it can be seen that Example 2 has a higher reverberation sound absorption rate than Comparative Examples 4 and 5 in substantially the entire measurement frequency range. Therefore, the vehicle floor carpet can improve sound absorption by increasing the expansion ratio along the direction from the skin material 4 to the base material 2.

Next, effects of the present embodiment configured as described above will be described below.
(1) In the above embodiment, the base material 2 and the skin material 4 are continuously bonded to the base material 2 and the skin material 4 to increase the expansion ratio along the direction from the skin material 4 to the base material 2. A backing layer 3 having a cell structure was provided.

  Therefore, the sound hitting the skin material 4 can be confined by propagating to the inside of the backing layer 3 with a low expansion ratio. And the sound by which the discharge | release to the compartment side was suppressed again can be disperse | distributed and attenuate | damped by high foaming magnification. As a result, the weight of the vehicle floor mat 1 can be reduced, and the sound absorption can be improved.

  (2) In the above embodiment, between the base material 2 and the skin material 4, a high expansion ratio layer 3H (3.5 times to 8.0 times) that adheres to the base material 2 and a low strength that adheres to the skin material 4 A backing layer 3 having a two-layer structure composed of an expansion ratio layer 3L (1.5 cups to 4.0 times) was provided. Therefore, the low expansion ratio layer 3L propagates the sound hitting the skin material 4 to the high expansion ratio layer 3H and confines it. The high expansion ratio layer 3H reliably attenuates the sound trapped inside the backing layer 3. As a result, the sound absorption of the vehicle floor mat 1 can be improved more reliably.

  (3) In the said embodiment, the foamed resin material apply | coated between the base material 2 and the skin material 4 was heated at high temperature by the base material 2 side, and low temperature heating was carried out simultaneously by the skin material 4 side. Then, the backing layer 3 having the high expansion ratio layer 3H and the low expansion ratio layer 3L was formed by heating a single foamed resin material.

  Therefore, the number of parts of the vehicle floor mat 1 can be reduced and the configuration can be simplified as compared with the case where a foam layer with a high expansion ratio and a foam layer with a low expansion ratio are laminated.

Moreover, productivity of the floor mat 1 for vehicles can be improved compared with the case where the foamed resin material by the side of the base material 2 and the foamed resin material by the side of the skin material 4 are each heated separately.
(4) In addition, only by changing the heating temperature on the base material 2 side and the heating temperature on the skin material 4 side, the propagation and attenuation of the sound hitting the backing layer 3 and further the frequency dependence of the sound absorption effect can be achieved. Can be controlled. Therefore, the sound absorption of the backing layer 3 can be appropriately adapted to the design change of the vehicle floor mat 1, and the design range of the vehicle floor mat 1 can be expanded.

(5) In the above embodiment, the backing layer 3 ^has air permeability of ^{5cc / cm 2 / sec~20cc / cm} 2 / sec. Therefore, the backing layer 3 can propagate sound that cannot be sufficiently attenuated to the back side. As a result, the backing layer 3 can cause the base material 2 to absorb sound that cannot be sufficiently attenuated, or can cause other sound absorbing material installed on the back side of the vehicle floor mat 1 to absorb sound.

In addition, this invention can also be changed and embodied as follows.
In the above embodiment, the sound absorbing material is embodied as a vehicle floor mat. However, the present invention is not limited to this. For example, the sound absorbing material may be embodied in a vehicle carpet or an interior panel, and may absorb sound. That's fine.

  -In the said embodiment, it was set as the structure which provides the difference in the heating (drying) temperature of a foamed resin material, and has a gradient in a foaming ratio. For example, a difference may be provided in the heating (drying) time of the foamed resin material so that the foaming magnification has a gradient.

Sectional drawing of the floor mat for vehicles which actualized this invention. Similarly, SEM image of the foam layer. Similarly, explanatory drawing explaining the manufacturing system of the floor mat for vehicles. Similarly, explanatory drawing explaining the normal incidence sound absorption coefficient of a foaming layer. Similarly, explanatory drawing explaining the reverberation room method sound absorption rate of a floor mat for vehicles.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle floor mat as a sound absorbing material, 2 ... Base material, 3 ... Backing layer as a foam layer, 3H ... High foaming magnification layer, 3L ... Low foaming magnification layer, 4 ... Skin material, 10 ... Vehicle floor mat Manufacturing system.

Claims (2)

An application step of applying a foamed resin material to the back surface of the skin material;
With the foamed resin material applied, a foam layer that heats the surface side of the skin material at a predetermined temperature and heats the back surface side of the skin material at a temperature higher than the predetermined temperature to adhere to the back surface of the skin material And a foaming step of increasing the foaming ratio of the foam layer in the direction from the skin material toward the foam layer,
Equipped with a,
The foaming step includes
A method for producing a sound-absorbing material , comprising heating the skin material side at a predetermined temperature and simultaneously heating the back surface side of the skin material at a temperature higher than the predetermined temperature . An application step of applying a foamed resin material to either the skin material or the base material;
A bonding step of bonding the skin material and the base material through the foamed resin material;
In the state in which the skin material and the base material are bonded together, the skin material side and the base material side are heated at a predetermined temperature and a temperature higher than the predetermined temperature, respectively, and foamed to adhere to the skin material and the base material. Forming a layer and increasing the foaming ratio of the foam layer from the skin material side toward the base material side;
Equipped with a,
The foaming step includes
A method for producing a sound-absorbing material , comprising heating the skin material side at a predetermined temperature and simultaneously heating the base material side at a temperature higher than the predetermined temperature .

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