JP5902565B2 - Sound absorbing material and method for producing sound absorbing material - Google Patents

Description

  The present invention relates to a sound absorbing material using a pulp fiber component, a synthetic resin component, and a starch component as an auxiliary agent as a foaming material, and a method for producing the same.

  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 An object is to provide a manufacturing method.

  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 melt flow rate. Is a polypropylene resin having a weight of 20 g / 10 min to 30 g / 10 min.

  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 layers include those in which foamed cells having a foaming density lower than that of each surface coating layer are densely arranged. 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 embodiment of the present invention uses an extrusion molding machine provided with discharge ports provided 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 polypropylene fiber component having a pulp fiber component and a melt flow rate of 20 g / 10 min to 30 g / 10 min, a starch component and water as an auxiliary agent are supplied, 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 each discharge port by pressing.

  According to the present invention, since the synthetic resin component has a high melt flow rate (MFR), each foam cell can swell greatly because the fluidity of the foam material is high in the foaming process, As a result, the foamed cell in which a large number of spaces are formed becomes a sparse structure. When the sound absorbing material is subjected to sound vibrations, the cell structure is in a sparse state, so the air permeability of the epidermis increases, passes through the foam cells, and each foam cell vibrates throughout the structure due to the sound, and the vibration is foamed. It enters the air layer inside the cell and absorbs 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.

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. It is a figure which shows one Embodiment of this invention and shows the physical property (MFR etc.) of each synthetic resin material. 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. 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. FIG. 5 is a characteristic diagram of a sound absorption coefficient according to a reverberation chamber method in a sound absorbing material having no partition coating layer (in the case of a single base) and a sound absorbing material having a partition coating layer according to another embodiment of the present invention.

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

(One embodiment)
1 to 6 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 material having a melt flow rate (hereinafter referred to as “MFR”) in the range of 20 g / 10 min to 30 g / 10 min is used. Specifically, as shown in FIG. 4, any one of J3000GP, J2000GP, J2003GP, and J2041GA (all of which are types of Prime Polymer, Inc., Prime Polymer Co., Ltd.) is used.

  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 resin component, a polypropylene resin material having an MFR in the range of 20 g / 10 min to 30 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, not only the flexibility of the paper powder component and the adhesiveness of corn starch, but also the synthetic resin component has a high MRF value, the foam material exhibits high fluidity, and the MFR has a low value. Each foam cell S3 swells greatly compared to the one. 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.

  In the sound absorbing material 1A having such a configuration, since the foamed cells S2 and S3 forming a large number of spaces are arranged in a dense state, the vibration of air is large and the passage of sound through the skin portion is appropriately promoted. The surface film layer 2 of the sound absorbing material 1 </ b> A is appropriately ventilated and vibrated by the ventilation of air, and this vibration is transmitted to the foamed cell layer 3. Since the foam cell layer 3 is large and the cell structure is sparse, a portion near the skin of each foam cell S3 vibrates due to sound, and the vibration enters the air layer inside the foam cell S3. , Absorb the sound as a whole.

  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.

  5 and 6 show the sound absorption rate measurement results obtained by the reverberation chamber method for various sound absorbing materials. As shown in FIG. 5, J3000GP (trade name of Prime Polymer Co., Ltd .: MFR: 30 g / 10 min, a product of Prime Polymer Co., Ltd.), J2000GP (trade name of Prime Polymer Co., Ltd .: MFR: 21 g, a product of Prime Polymer Co., Ltd.) / 10 min), J2003GP (trade name of Prime Polymer Co., Ltd .: MFR: 21 g / 10 min with a kind of Prime Polypro), J2041GP (trade name of Prime Polymer Co., Ltd .: MFR: 22 g / 10 min with a kind of Prime Polypro) Compared to felt and cinsalate which are typical sound absorbing materials, a high sound absorbing rate was exhibited in a range of about 1000 to 2000 Hz. Therefore, it was confirmed that a high sound absorption characteristic is exhibited in the range of the speech intelligibility of 1000 Hz to 2000 Hz. For example, it is suitable as a sound absorbing material 1A used in an automobile. In particular, J3000GP exhibited a high sound absorption coefficient of 0.8 at the maximum in the range of 1/3 octave band center frequency of 1250 to 2000 Hz.

  In addition, the polypropylene resin J700GP (Prime Polymer's product name: Prime Polypro, MFR: 8 g / 10 min) has lower sound absorption in all frequency bands compared to general sound absorbing materials such as felt and cinsalate. Only rate was shown. From the above, the sound-absorbing material, which is made of a foam having paper as a part of the foam material, and uses a polypropylene resin having an MFR of 20 g / 10 min to 30 g / 10 min as a part of the foam material, is as described above. It was confirmed that the sound absorption characteristics were improved.

  As shown in FIG. 6, H700 of polypropylene resin (Prime Polymer Co., Ltd. product name: Prime Polypro, MFR: 8 g / 10 min) is around 2000 Hz compared to felt and cinsalate, which are general sound absorbing materials. The sound absorption coefficient was slightly higher in the frequency band of, but only a low sound absorption coefficient was exhibited in the other frequency bands. With respect to H700 having a low MFR, the sound absorption coefficient was measured while varying the density, but almost the same result was obtained.

  As described above, a polypropylene resin having a MFR value in the range of 20 g / 10 min to 30 g / 10 min is used because the MFR value is closely related to the sound absorption characteristics. Thus, the sound absorbing material 1A exhibiting excellent sound absorbing performance can be obtained.

Further, for J3000GP having a high MFR, the sound absorption coefficient was measured by varying the density. FIG. 5 shows the characteristics when the density is 42 kg / m ³ , and FIG. 6 shows the characteristics when the density is 32 kg / m ³ . The smaller the density, the better the sound absorption characteristics. As a result, it was confirmed that the density is closely related to the sound absorption characteristics in a synthetic resin material having a high MFR.

(Other embodiments)
7 to 9 show other embodiments. 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. 7, 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.

In FIG. 6, when the synthetic resin component is polypropylene resin H700 and the density of both structures is 37 kg / m ³ , the sound-absorbing material 1A without the partition coating layer 4 (in the case of a single base) and the partition coating layer 4 The sound absorption coefficient measurement result by the reverberation chamber method is shown for the sound absorbing material 1B (in the case of a two-stage base) having the above. The partition coating layer 4 affects vibration absorption, and the sound absorbing material 1B having the partition coating layer 4 is higher in the range of the speech intelligibility of 1000 Hz to 2000 Hz than the sound absorbing material 1A having no partition coating layer 4. It was confirmed that the sound absorbing characteristics were exhibited. Thereby, the vibration absorption effect by the partition coat layer 4 was confirmed.

In FIG. 6, in the case of the sound absorbing material 1B (in the case of a two-stage base) in which the synthetic resin component is polypropylene resin H700 and both have the partition film layer 4, the structure has a density of 37 kg / m ³ and the structure. The results of measuring the sound absorption rate by the reverberation chamber method when the density of the sample is 27 kg / m ³ are shown. By reducing the density of the structure, the frequency region exhibiting high sound absorption characteristics was expanded, and the vibration absorption effect due to the density was confirmed.

FIG. 9 shows that the synthetic resin component is J3000GP made of polypropylene resin, and the sound absorbing material 1A (42 kg / m ^{3 in} the case of one stage of the base) and the sound absorbing material 1B (the base 2 of the base 2 having no partition film layer 4). In the case of a stage, the sound absorption coefficient is measured by the reverberation chamber method at 32 kg / m ³ ). It was confirmed that a high sound-absorbing characteristic was exhibited in the region of speech intelligibility from 1000 Hz to 2000 Hz by the synergistic effect of the vibration absorption effect by the partition coating layer 4 and the vibration absorption effect by the density of the structure. For example, it is suitable as a sound absorbing material 1A used in an automobile.

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

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 (4)

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 synthetic resin component, sound absorbing material, characterized in that the melt flow rate is a polypropylene resin of ^20g _/ 10 ^min~30g _/ 10 min. The sound-absorbing material according to claim 1,
The foamed cell is composed of a surface coating layer, a foamed cell layer, and a surface coating layer along the thickness direction. Each surface coating layer has an extremely thin thickness, and a foamed cell having a foaming density higher than that of the foamed cell layer. A sound-absorbing material, wherein the foamed cell layers are densely arranged, and the foamed cell layers are densely arranged with foamed cells having a lower foam density than the respective surface coating layers. The sound-absorbing material according to claim 1 or 2,
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 component having a melt flow rate of 20 g / 10 min to 30 g / 10 min, a starch component as an auxiliary agent and water are supplied to the extrusion molding machine, and the pulp fiber component, a synthetic resin component, a starch component and water are supplied. A method for producing a sound-absorbing material, characterized in that the material is heated and kneaded and discharged from each discharge port by pressing.

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