JP2014025051A - Sound absorption material, method for producing sound absorption material, and door structure of automobile using sound absorption material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorption material excellent in sound absorption characteristic, comprising a foam using paper as a part of a foaming material, and to provide a method for producing the sound absorption material, and a door structure using the sound absorption material.SOLUTION: A sound absorption material 1A is constituted of foaming cells S2, S3 having many spaces formed therein, by foaming a pulp fiber component, a synthetic resin component and a starch component as an auxiliary material. The synthetic resin component is a polyethylene resin or a polypropylene resin having a rubber-based material added thereto, for example, J715M (trade name of stock company 'Prime Polymer', a kind of prime polypropylene), which is a structure whose cell structure is in the non-dense state. Further, the sound absorption material 1A is used as a pad member of a door structure of an automobile.

Description

  The present invention relates to a sound absorbing material in which a pulp fiber component, a synthetic resin component, and a starch component as an auxiliary agent are used as a foaming material, a method for producing the same, and a door structure of an automobile using the sound absorbing material.

  Conventionally, a foam using paper as a part of a foam material has been proposed (see Patent Documents 1 and 2). Since this foam can use waste paper as a pulp fiber component, it is suitable for paper recycling. And since the foaming cell in which the foam formed many spaces is densely arrange | positioned in a foam, the passage of air can be stopped moderately and it can anticipate also as a favorable sound-absorbing material.

Japanese Patent No. 3326156 JP 2000-273800 A

  However, there is a demand for a foam that uses paper as a part of the foam material and that has even better sound absorption characteristics.

  Therefore, the present invention has been made to solve the above-described problems, and is made of a foam having paper as a part of a foam material. The sound absorber has excellent sound absorption characteristics, and It is an object of the present invention to provide a manufacturing method and an automobile door structure using the sound absorbing material.

  The present invention is a sound-absorbing material composed of foamed cells in which a pulp fiber component, a synthetic resin component and a starch component as an auxiliary agent are foamed to form a large number of spaces, and the synthetic resin component is a polyethylene resin or rubber. It is a sound absorbing material characterized by being a polypropylene resin to which a system material is added.

  The polypropylene resin is preferably J715M (a kind of product name Prime Polypro of Prime Polymer Co., Ltd.). It is preferable to have a partition coat layer extending along the direction perpendicular to the thickness direction at an intermediate position in the thickness direction.

  Another aspect of the present invention uses an extrusion molding machine provided with discharge ports arranged at intervals, and provided with a regulation frame wall for regulating a foaming region of a foam discharged from each of the discharge ports, A pulp fiber component, a polypropylene resin to which a polyethylene resin or rubber-based material is added, a starch component and water as an auxiliary agent are supplied to an extrusion molding machine, and the pulp fiber component, the synthetic resin component, the starch component and water are heated and kneaded. And a method for producing a sound-absorbing material, wherein the sound-absorbing material is discharged from the discharge ports by a pressing force.

  Another aspect of the present invention is an automobile door structure in which a door trim is assembled to a vehicle interior side of an inner panel that forms a door of the automobile, the vehicle interior side surface of the inner panel and the back surface of the door trim on the inner panel side. A pad member made of the sound absorbing material according to any one of claims 1 to 4 is sandwiched between the two.

  The pad member is preferably disposed at least between a plurality of assembly members for assembling the door trim to the inner panel.

  According to the present invention, since the synthetic resin component is a polypropylene resin to which a polyethylene resin or a rubber-based material is added, in the foaming process, the flowability of the foaming material increases, so that each foamed cell expands greatly. Thus, a foamed cell in which a large number of spaces are formed, and the cell structure becomes a sparse structure. When the sound absorbing material receives sound vibrations, the cell structure is in a sparse state, so each foam cell vibrates due to sound, and the vibration enters the air layer inside the foam cell and absorbs the sound. As described above, the sound absorbing characteristic is obtained in the case where the paper is made of a foam having a part of the foam material.

  In addition, by using the sound absorbing material as a pad member between the inner panel, which is a door structure of an automobile, and a door trim, it is possible to make it difficult to absorb sound from outside the passenger compartment and transmit it to the passenger compartment. In addition to being able to be a quiet space, the foam member forming the sound absorbing material of the pad member made of the above sound absorbing material exhibits high fluidity, and each foam cell swells greatly like a material having a high MRF. As a result, the cell structure composed of the foam cells is configured in a sparse state, and when the foam cells expand greatly, the thickness of each foam cell becomes thin, and the pad member sandwiched between the door trim and the inner panel becomes thin. The vehicle interior space can be widened accordingly.

  In addition, since it has a high cushioning property, it can function as an original pad member by sandwiching the door trim when it is assembled to the inner panel, and the pad member itself can be formed thinly. Can be assembled closer to the inner panel side, so that the interior space of the vehicle can be widened, and the door trim can be securely attached to the inner panel. The room can be a quiet space.

1 is an external perspective view of a sound absorbing material according to an embodiment of the present invention. FIG. 2 is a structural schematic diagram of a sound absorbing material according to an embodiment of the present invention. 1 shows an embodiment of the present invention, (a) is a perspective view of a main part of an extrusion molding machine, and (b) is a front view of a base member. FIG. 4 is a characteristic diagram of sound absorption coefficient according to a reverberation chamber method for various sound absorbing materials according to an embodiment of the present invention. FIG. 5 is a structural schematic diagram of a sound absorbing material according to another embodiment of the present invention. The other embodiment of this invention is shown, (a) is a principal part perspective view of an extrusion molding machine, (b) is a front view of a nozzle | cap | die member. It is sectional drawing which shows other embodiment of this invention and shows the door structure of a motor vehicle.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(One embodiment)
1 to 4 show an embodiment of the present invention. As shown in FIG. 1, the sound absorbing material 1A is a flat rectangular plate-like foam. The sound absorbing material 1A is composed of foam cells S1, S2, and S3 in which a paper powder component that is a pulp fiber component, a synthetic resin component, and corn starch that is a starch component as an auxiliary agent are foamed to form a large number of spaces. (See FIG. 2). As the paper powder component, used paper such as government postcards made into paper powder fiber is used. As the synthetic resin component, a polypropylene resin to which a polyethylene resin or a rubber-based material is added is used. In this embodiment, J715M (trade name of Prime Polymer Co., Ltd .: a kind of Prime Polypro) is used as the polypropylene resin.

  As for each foaming cell S1, S2, S3, the internal space | gap is covered with the cell membrane | film | coat. The foam cells S1, S2, S3 have different foam densities (foaming ratios) depending on their positions, and the foam 1A is formed in the following layer structure depending on the density of the foam cells S1, S2, S3.

  That is, the sound absorbing material 1 </ b> A is composed of the surface coating layer 2, the foamed cell layer 3, and the surface coating layer 2 along the thickness direction. Each surface coating layer 2 has an extremely thin thickness, and foam cells S2 having a foam density higher than the foam cell layer 3 are densely arranged. In each foam cell layer 3, foam cells S3 having a foam density lower than that of each surface coating layer 2 are densely arranged.

  Each foamed cell layer 3 is formed with a plurality of vertical partition coating layers 5 at equal intervals along the direction perpendicular to the thickness direction. Each foam cell layer 3 is divided by a longitudinal partition coating layer 5. In the vertical partition coating layer 5, foam cells S <b> 2 having a foam density higher than that of the foam cell layer 3 are densely arranged.

Next, an extrusion molding machine 10 that manufactures the foam 1A will be described. As shown in FIG. 3A, the extrusion molding machine 10 is kneaded with an inlet (not shown) for charging each foamed material, and a kneading means (not shown) for kneading the charged foamed material. A heating means (not shown) for heating the foamed material to a high temperature, a pressing means (not shown) for pressing the foamed material, a base member 11 arranged so as to close the front end side of the pressing chamber, and the base And a regulating frame wall 20 disposed so as to surround the outside of the member 11. As shown in FIGS. 3A and 3B, the base member 11 has a plurality of discharge ports 12 arranged at equal intervals P in the horizontal direction. Each discharge port 12 is arrange | positioned in the same position with respect to the horizontal direction. The restriction frame wall 20 restricts the foaming region of the foam material discharged from the discharge port 12. The regulation frame wall 20 is a flat rectangular frame.

  Next, a method for manufacturing the foam 1A will be described. In the extrusion molding machine 10, a paper powder component, a polypropylene resin material having an MFR in the range of 10 ± 2 g / 10 min, corn starch as an auxiliary agent, and water are supplied. Then, the paper powder component, polypropylene resin material, corn starch, and water are kneaded with heat, and this high-temperature foam material is discharged from the first discharge port 12 of the base member 11 by pressing.

  Then, the water mixed in the high-temperature foam material is vaporized at the moment when the water is discharged from each discharge port 12, and the foam material composed of the paper powder component, the polypropylene resin material and the corn starch is foamed by the vapor pressure of the water. Since the foaming is regulated by the regulation frame wall 20, the foam 1A having the regulation frame wall 20 as a cross-sectional area is continuously extruded. Each of the foamed cells S2, S3 is a space formed by appropriate foaming depending on the flexibility of the paper powder component and the adhesiveness of corn starch.

  Moreover, the foam material discharged from each discharge port 12 cannot be foamed freely, and as described above, foam formation is suppressed by the regulation frame wall 20 and foam formation is suppressed by the foam cells interfering with each other. Is done. Specifically, the foaming cell S <b> 2 located in the vicinity of the inner periphery of the regulation frame wall 20 is suppressed from being foamed by the regulation frame wall 20. Thereby, the surface film layer 2 is formed. In the foam cell S2 located near the intermediate position between the discharge ports 12 adjacent in the horizontal direction, the foam cells S2 collide (interfere) with each other, and foam formation is suppressed. Thereby, the vertical partition film layer 5 is formed. The foamed cell S3 located at the inner side of these functions only with a weak suppression force compared to the foamed cell S2. Thereby, the foam cell layer 3 is formed.

  In the above foaming process, the paper powder component exhibits flexibility and the corn starch exhibits adhesiveness, but the synthetic resin component also exhibits flexibility and adhesiveness due to the flexibility of the polypropylene resin and the rubber-based adhesiveness. The foam material exhibits high fluidity, and each foam cell S3 swells greatly in the same manner as a material having a high MFR. Thereby, the cell structure which consists of foam cell S3 is comprised in a sparse state. Further, when the foam cell S3 swells greatly, the film thickness of each foam cell S3 becomes thin.

  The sound absorbing material 1A having such a configuration appropriately blocks the vibration of air, that is, the passage of sound, because the foamed cells S2, S3 forming a large number of spaces are arranged in a dense state. However, the surface film layer 2 of the sound absorbing material 1 </ b> A vibrates due to the vibration of air, and this vibration is transmitted to the foamed cell layer 3. Since the foam cell S3 is large and the cell structure is sparse, each foam cell S3 vibrates with sound, and the vibration enters the air layer inside the foam cell S3 and absorbs the sound. .

  In addition, since the film thickness of each foamed cell S3 is thin, the film of each foamed cell S3 is likely to vibrate, and sound is also absorbed by the vibration of the film. As described above, the sound absorbing material 1A made of a foam having paper as a part of the foam material exhibits excellent sound absorbing characteristics.

  FIG. 4 shows the sound absorption coefficient measurement results obtained by the reverberation chamber method for various sound absorbing materials. As shown in FIG. 4, J715M, which is a polypropylene resin, exhibited a high sound absorption rate in the range of 1/3 octave band center frequency of 1250 to 2000 Hz, compared to felt and cinsalate, which are general sound absorbing materials. Therefore, it was confirmed that a high sound-absorbing characteristic was exhibited in the range of speech intelligibility of approximately 1000 Hz to 2000 Hz. For example, it is suitable as a sound absorbing material 1A used in an automobile.

  In FIG. 4, H700 (trade name of Prime Polymer Co., Ltd .: a type of Prime Polypro) is a type of the same polypropylene resin. H700 is a resin having a low melt flow rate (MFR) of 8 g / 10 min. Although J715M has a low melt flow rate (MFR) of 10 ± 2 g / 10 min, it is considered that it exhibits excellent sound absorption characteristics due to its high fluidity during foaming for the reasons described above.

(Other embodiments)
5 and 6 show another embodiment. The sound absorbing material 1B is made of foamed paper powder component that is a pulp fiber component, a synthetic resin component, and corn starch that is a starch component as an auxiliary agent, and is composed of a large number of sealed foam cells S1, S2, and S3. (See FIG. 7). As the paper powder component, used paper such as government postcards made into paper powder fiber is used. The synthetic resin component is the same as in the first embodiment.

  As shown in FIG. 5, the sound absorbing material 1 </ b> B is different in structure from that of the above embodiment. That is, the sound absorbing material 1B is composed of the surface coating layer 2, the foam cell layer 3, the partition coating layer 4, the foam cell layer 3, and the surface coating layer 2 along the thickness direction. Each surface coating layer 2 has an extremely thin thickness, and foam cells S2 having a foam density higher than the foam cell layer 3 are densely arranged. In each foam cell layer 3, foam cells S3 having a foam density lower than that of the partition coating layer 4 are densely arranged. In the partition coating layer 4, the foam cells S <b> 1 having a higher foam density than the foam cell layer 3 and the surface coating layer 2 are densely arranged. The partition coat layer 4 continuously partitions between the two foam cell layers 3. The partition coat layer 4 is straight in the direction orthogonal to the thickness direction and has substantially the same thickness.

  Each foamed cell layer 3 is formed with a plurality of vertical partition coating layers 5 at equal intervals along the direction perpendicular to the thickness direction. Each foam cell layer 3 is divided by a longitudinal partition coating layer 5. In the vertical partition coating layer 5, foam cells S <b> 2 having a foam density higher than that of the foam cell layer 3 are densely arranged.

  Next, an extrusion molding machine 10 that manufactures the foam 1B will be described. As shown in FIG. 8, the extrusion molding machine 10 has a plurality of discharge ports 12 and 13 which are arranged at equal intervals P in the horizontal direction on the base member 11. Has a stage. Since other configurations are the same, redundant description is omitted. The same components in the drawings are given the same reference numerals for clarification.

  This sound absorbing material 1B also exhibits excellent sound absorbing characteristics for the same reason as in the above embodiment.

  In addition, the sound-absorbing material 1B has a partition coating layer 4 extending along the direction perpendicular to the thickness direction at an intermediate position in the thickness direction. Thereby, when the vibration propagating in the foamed cell layer 3 of the sound absorbing material 1B reaches the partition coating layer 4, the random vibration is reset to the plane vibration in the partition coating layer 4, and then further propagates in the foamed cell layer 3. Therefore, it is considered that vibration absorption is promoted by the partition coating layer 4 and further excellent sound absorption characteristics are exhibited.

(Other)
The foam 1B of this other embodiment has the partition coating layer 4 at one location, but may have the partition coating layer 4 at two or more locations. The more the partition coating layer 4 is, the better the sound absorption characteristics.

(Other embodiments)
Next, the door structure of the automobile using the sound absorbing materials 1A and 1B in the above embodiments will be described with reference to FIG.

  As shown in FIG. 7, in the door structure 21 of the automobile according to the present embodiment, a door trim 25 is assembled on the vehicle interior 24 side of the inner panel 23 that forms the door 22. A pad member 29 made of the sound absorbing materials 1A and 1B in the above embodiment is sandwiched between a surface 26 of the inner panel 23 on the vehicle interior 24 side and a back surface 28 of the door trim 25 on the inner panel 23 side (vehicle exterior 27 side). ing. The pad member 29 is disposed at least between the plurality of assembly members 30 for assembling the door trim 25 to the inner panel 23.

  A plurality of clips as assembling members 30 are attached to the rear surface 28 side of the door trim 25, and these clips penetrate through the pad member 29 and engage with attachment holes provided in the inner panel 23. The door trim 25 is assembled to the inner panel 23.

  As shown in the above embodiments, the sound absorbing materials 1A and 1B are in the foaming process, and the paper powder component exhibits flexibility and the corn starch exhibits adhesiveness. It exhibits flexibility and tackiness due to its rubber-based tackiness. Thereby, sound-absorbing material 1A, 1B has a softness | flexibility and has a high cushioning property. Therefore, the door trim 25 can be used as a pad member in the same manner as a pad member made of polyether foam, polyethylene foam, vinyl chloride foam, or resin-impregnated polyether foam that is generally used when the door trim 25 is assembled to the inner panel 23.

  Furthermore, as described in the above embodiment, the pad member 29 of the present embodiment made of the sound absorbing materials 1A and 1B exhibits high fluidity in the foam material forming the sound absorbing materials 1A and 1B, and is the same as the material having a high MFR. In addition, each foam cell S3 swells greatly. Thereby, the cell structure which consists of foam cell S3 is comprised in a sparse state. Further, since the foam cell S3 swells greatly, the film thickness of each foam cell S3 becomes thin, and the pad member sandwiched between the door trim 25 and the inner panel 23 can be formed thinly. The vehicle interior space can be widened.

  Further, as described in the above embodiment, since the sound absorbing materials 1A and 1B have the foam cells S2 and S3 forming a large number of spaces arranged in a dense state, vibration of air, that is, passage of sound is moderate. To stop. However, the surface film layer 2 of the sound absorbing material 1 </ b> A vibrates due to the vibration of air, and this vibration is transmitted to the foamed cell layer 3. Since the foam cell S3 is large and the cell structure is sparse, each foam cell S3 vibrates with sound, and the vibration enters the air layer inside the foam cell S3 and absorbs the sound. . Further, the pad member 29 made of the sound absorbing materials 1A and 1B has a thin film thickness of each foamed cell S3, so that the film of each foamed cell S3 is likely to vibrate and absorbs sound even by vibration of the film. As described above, the sound absorbing material 1A made of a foam having paper as a part of the foam material exhibits excellent sound absorbing characteristics.

  Therefore, by forming the pad member with the sound absorbing materials 1A and 1B having such characteristics, the sound from the outside 27 of the passenger compartment is absorbed, and the sound of the outside 27 of the passenger compartment is hardly transmitted to the inside 24 of the passenger compartment. Thus, the interior of the vehicle interior 24 can be made a quieter space. Further, since it has a high cushioning property, it can function as an original pad member by sandwiching the door trim 25 when it is assembled to the inner panel 23, and the pad member 29 itself can be formed thin. Therefore, the door trim 25 can be assembled closer to the inner panel 23 side, so that the vehicle interior space can be increased accordingly.

  In FIG. 7, reference numeral 31 denotes an outer panel, and reference numeral 32 denotes a pocket portion formed integrally with the door trim.

1A, 1B Sound absorbing material S1, S2, S3 Foamed cell 2 Surface film layer 3 Foamed cell layer 4 Partition film layer 10 Extruder 12, 13 Discharge port 20 Restriction frame wall

Claims (7)

A sound absorbing material composed of foam cells in which a pulp fiber component, a synthetic resin component, and a starch component as an auxiliary agent are foamed to form a large number of spaces,
The sound absorbing material, wherein the synthetic resin component is a polypropylene resin to which a polyethylene resin or a rubber-based material is added. The sound-absorbing material according to claim 1,
The polypropylene resin is J715M (trade name of Prime Polymer Co., Ltd .: a kind of Prime Polypro), a sound absorbing material. The sound-absorbing material according to claim 1 or 2,
The foamed cell is composed of a surface coating layer, a foamed cell layer, and a surface coating layer along the thickness direction, and each surface coating layer is formed by closely arranging foamed cells having a foaming density higher than that of the foamed cell layer. The layer is densely arranged with foam cells having a foam density lower than that of each surface coating layer. The sound-absorbing material according to any one of claims 1 to 3,
A sound-absorbing material having a partition coating layer extending along a direction orthogonal to the thickness direction at an intermediate position in the thickness direction. Using an extrusion molding machine provided with discharge ports arranged at intervals and provided with a regulation frame wall for regulating the foaming area of the foam discharged from each of the discharge ports,
A pulp fiber component, a polypropylene resin to which polyethylene resin or a rubber-based material is added, a starch component and water as an auxiliary agent are supplied to the extrusion molding machine, and the pulp fiber component, a synthetic resin component, a starch component and water are heated and kneaded. A method for producing a sound-absorbing material, wherein the sound-absorbing material is discharged from the discharge ports by a pressing force. A door structure of an automobile in which a door trim is assembled on the vehicle interior side of the inner panel forming the door of the automobile,
A pad member made of a sound absorbing material according to any one of claims 1 to 4, wherein a pad member made of the sound absorbing material according to any one of claims 1 to 4 is sandwiched between a surface of the inner panel on the vehicle interior side and a back surface of the door trim on the inner panel side. Automobile door structure. The automobile door structure according to claim 6,
The automobile door structure, wherein the pad member is disposed at least between a plurality of assembly members for assembling the door trim to the inner panel.

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