JP6055318B2 - Foam - Google Patents

Description

  The present invention relates to a foamed product comprising a pulp fiber component, a synthetic resin component, and a starch component as an auxiliary agent as a foaming 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. As shown in FIGS. 21A and 21B, the foam 50 foams 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. It is comprised from foam cell S2, S3. Each foam cell S2, S3 has an internal space (air layer) covered with a cell coating. The foam 50 has different foam densities (foaming ratios) of the foam cells S2 and S3 depending on the position thereof, and is roughly configured in a three-layer structure including a foam cell layer 53 and two surface coating layers 52 disposed on both sides. Has been. Each surface film layer 52 has an extremely thin thickness, and foam cells S2 having a foam density higher than the foam cell layer 53 are densely arranged. In the foam cell layer 53, the foam cells S3 having a foam density lower than that of the respective surface coating layers 52 are densely arranged.

  Next, an extrusion molding machine 60 for producing the foam 50 will be described. As shown in FIG. 22 (a), the extrusion molding machine 60 includes a charging port (not shown) for charging the foam material, kneading means (not shown) for kneading the charged foam material, and kneading foam. A heating means (not shown) for heating the material to a high temperature, a pressing means (not shown) for pressing the foam material, a base member 61 arranged so as to close the front end side of the pressing chamber, and the base member 61 And a regulation frame wall 70 arranged so as to surround the outside. As shown in FIG. 22B, the base member 61 has a plurality of discharge ports 62 arranged at equal intervals in the horizontal direction. The discharge port 62 is one stage. The restriction frame wall 70 restricts the foaming region of the foam material discharged from the plurality of discharge ports 62. The restriction frame wall 70 is a flat rectangular frame.

  Next, the manufacturing method of the foam 50 is demonstrated. A paper powder component, a polypropylene resin material, corn starch as an auxiliary agent, and water are supplied into the extrusion molding machine 60. 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 plurality of discharge ports 62 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 62, and the foam material composed of the paper powder component, the polypropylene resin material, and the corn starch is foamed by the water vapor pressure. Since the foaming is regulated by the regulation frame wall 70, the foam 50 having the regulation frame wall 70 as a cross-sectional area is continuously extruded. Each of the foamed cells S2 and S3 is hermetically sealed without being broken by the flexibility of the paper powder component, the adhesiveness of corn starch, and the like.

  The foam 50 having such a structure has sound absorption characteristics as shown in FIG. This sound absorption characteristic is considered to be a combination of the resonance effect and the porous type. That is, the sound absorption performance due to the resonance effect is due to the cancellation of the surface reflected wave reflected by the surface coating layer 52 and the transmitted reflected wave that enters the foam 50 and returns as the reflected wave among the sound incident from the outside. (See the characteristic diagram of the resonance effect in FIG. 23). The sound absorption performance due to the resonance effect exhibits peak performance within a low frequency band of 1 kHz to 2 kHz. The sound absorption performance by the porous type is due to the sound absorption that enters the inside of the foam 50 vibrates in the internal space of the foam cells S2 and S3 and the coating of the foam cells S2 and S3, and energy absorption (thermal energy release) due to vibration. Yes (see the characteristic diagram of the porous effect in FIG. 23). The porous sound absorbing performance is not effective in the low frequency band and exhibits high sound absorbing performance in the high frequency band of 2 kHz or higher. The sound absorption performance of the porous type becomes higher as the frequency becomes higher even in the high frequency band.

  FIG. 23 shows a comparison of sound absorption characteristics between the foam 50 and Shinsalate (registered trademark). Synthalate is an intertwined fabric (nonwoven fabric) of synthetic fibers, and exhibits a sound absorption performance by a porous type. As shown in FIG. 23, since the foam 50 has a sound absorption peak due to a resonance effect in a low frequency band (a band of approximately 1 kHz to 2 kHz), it exhibits sound absorption characteristics superior to a synthesizer.

Japanese Patent No. 3326156 JP 2000-273800 A JP-A-8-207170

  However, the above-described conventional foam 50 is inferior in sound absorption performance by the porous mold to that of cinsalate. Therefore, there is a band where the sound absorption performance is extremely lower than that of the synthesizer in a frequency band higher than the frequency band of the sound absorption peak due to the resonance effect, specifically, in a high frequency band of approximately 2 kHz or more.

  Therefore, the present invention has been made to solve the above-described problems, and provides a foam that has a sound absorption peak performance in a low frequency band and that can suppress a decrease in sound absorption performance in a high frequency band. With the goal.

The present invention is a foam 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 foamed cell is a foamed cell layer. And a surface coating layer in which foam cells having a foam density higher than that of the foam cell layer are arranged on the surface side of the foam cell layer, and the foam cell layer. A partition coating layer in which the foam cells having a higher foam density than the surface coating layer are densely arranged is configured in the thickness direction, and the partition coating layer continuously partitions the plurality of foam cell layers, and at least one of them On the surface film layer side, a film rupture portion reaching the foam cell layer is provided.

  The film rupture portion may be a large number of small holes. The film rupture portion may be a number of cracks. The film rupture portion may be a large number of cuts. The cut may be provided along the same direction. The cut may be provided along a plurality of directions.

  The film rupture portion may be a stripped portion obtained by stripping a part of the surface film layer into a planar shape. The stripping portion includes a portion provided in a lattice pattern on the surface coating layer. The stripped portion includes a strip provided on the surface film layer.

  The synthetic resin component may be a polypropylene resin material J830HV (a kind of product name Prime Polypro of Prime Polymer Co., Ltd.).

  According to the present invention, since the sound incident on the foam from the outside has the surface film layer, the surface reflected wave reflected by the surface film layer and the transmitted reflected wave that enters the inside of the foam and returns as the reflected wave. The sound absorption peak performance can be obtained in the low frequency band by canceling the surface reflected wave and the transmitted reflected wave, that is, by the sound absorption characteristic due to the resonance effect. On the other hand, the sound incident on the foam from the outside easily enters the inside of the foam because the surface coating layer has a film breakage portion, so the amount of absorption due to vibration energy inside increases, and the porous type The sound absorption characteristic in the high frequency band by is improved as compared with the conventional foam. As described above, the sound absorption peak performance is obtained in the low frequency band, and the deterioration of the sound absorption performance in the high frequency band can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view of a foam, showing a first embodiment of the present invention. The 1st Embodiment of this invention is shown, (a) is the structure schematic diagram of the foam in alignment with the AA of FIG. 1, (b) is the principal part enlarged view of (a). 1 shows a first embodiment of the present invention, in which (a) is a surface view of the first surface coating layer side (roller side) of the foam, and (b) is a second surface coating layer side (mold surface side) of the foam. (C) is a schematic cross-sectional view of the foam (for the sake of clarity, the dimension in the thickness direction is enlarged). 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a perspective view of an essential part of an extrusion molding machine, and FIG. 1 shows a first embodiment of the present invention and is a schematic sectional view of an extrusion molding machine. FIG. 1 is a side view of a press according to a first embodiment of the present invention. It is a sound absorption characteristic line figure of a foam with a small hole (1st embodiment), only a press foam, and a cinsarate, showing a 1st embodiment of the present invention. FIG. 2 shows a second embodiment of the present invention, where (a) is a surface view of the first surface coating layer side (roller side) of the foam, and (b) is a schematic sectional view of the foam (for the sake of clarity, in the thickness direction). The dimensions are enlarged). It is a sound absorption characteristic diagram of a foam with a crack (2nd embodiment), a press only foam, and a cinsallate, showing a 2nd embodiment of the present invention. FIG. 3 shows a third embodiment of the present invention, where (a) is a surface view of the first surface coating layer side (roller side) of the foam, and (b) is a schematic sectional view of the foam (for the sake of clarity, in the thickness direction). The dimensions are enlarged). It is a sound absorption characteristic diagram of a foam with a notch (third embodiment), a press-only foam and a cinsalate, showing a third embodiment of the present invention. 4 shows a fourth embodiment of the present invention, (a) is a surface view of the first surface coating layer side (roller side) of the foam, (b) is a schematic sectional view of the foam (for the sake of clarity, in the thickness direction). The dimensions are enlarged). FIG. 9 is a sound absorption characteristic diagram of a crack / cut foam (fourth embodiment), a cracked foam, a press-only foam, and a cinsalate according to a fourth embodiment of the present invention. FIG. 5 shows a fifth embodiment of the present invention, where (a) is a surface view of the first surface film layer side (roller side) of the foam, and (b) is a schematic sectional view of the foam (for the sake of clarity, in the thickness direction). The dimensions are enlarged). FIG. 10 is a sound absorption characteristic diagram of a cross-cut foam (fifth embodiment), a cut foam and a cinsallate, showing a fifth embodiment of the present invention. It is a sound-absorption characteristic diagram of various foams, such as 1st-5th embodiment, and a cinsalate. 6 shows a sixth embodiment of the present invention, where (a) is a surface view of the first surface coating layer side (roller side) of the foam, and (b) is a schematic sectional view of the foam (for the sake of clarity, in the thickness direction). The dimensions are enlarged). FIG. 10 shows a sixth embodiment of the present invention, and is a sound absorption characteristic diagram of a grid-like stripped foam (sixth embodiment), a cross-cut foam, and a cinsallate. 7 shows a seventh embodiment of the present invention, (a) is a surface view of the first surface coating layer side (roller side) of the foam, (b) is a schematic sectional view of the foam (for the sake of clarity, in the thickness direction) The dimensions are enlarged). FIG. 10 is a sound absorption characteristic diagram of a striped stripped foam (seventh embodiment), a grid stripped foam, a cross-cut foam and a cinsallate, showing a seventh embodiment of the present invention. A prior art example is shown, (a) is an external appearance perspective view of a foam, (b) is a structural schematic diagram of a foam. A prior art example 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 a sound-absorption characteristic diagram of the foam of a conventional example, and a cinsalate.

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

(First embodiment)
1 to 7 show a first embodiment of the present invention. As shown in FIG. 1, the foam 1A has a flat rectangular plate shape. As shown in FIGS. 2 (a) and 2 (b), the foam 1A comprises a paper powder component that is a pulp fiber component, a polypropylene resin material that is a synthetic resin material, and corn starch that is a starch component as an auxiliary agent. It is composed of a number of foamed cells S1, S2, S3 which are foamed and sealed. As the paper powder component, used paper such as government postcards made into paper powder fiber is used. The synthetic resin component is a polypropylene resin material J830HV (a kind of product name Prime Polypro of Prime Polymer Co., Ltd.). J830HV has physical properties of a melt flow rate (test condition: 230 ° C.) of 30 g / 10 min, a density of 910 kg / m 3, a tensile yield stress of 28.0 MPa, a tensile fracture nominal strain of 30%, and a tensile elastic modulus of 1450 MPa.

  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 foam 1A is composed of the first surface coating layer 2A, the foam cell layer 3A, the partition coating layer 4, the foam cell layer 3B, and the second surface coating layer 2B along the thickness direction. The first and second surface coating layers 2A and 2B have an extremely thin thickness, and foam cells S2 having a foam density higher than the foam cell layers 3A and 3B are densely arranged. In each of the foam cell layers 3A and 3B, 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 cell S3 having a higher foam density than the foam cell layers 3A and 3B and the surface coating layers 2A and 2B are densely arranged. The partition coating layer 4 blocks and blocks the two foam cell layers 3A and 3B continuously. The partition coating layer 4 is substantially straight in the direction orthogonal to the thickness direction and has substantially the same thickness.

  In each of the foamed cell layers 3A and 3B, a plurality of vertical partition coating layers 5 are formed at equal intervals along the direction orthogonal to the thickness direction. Each of the foamed cell layers 3 </ b> A and 3 </ b> B is divided by the vertical partition coating layer 5. In the vertical partition coating layer 5, foam cells S2 having a foam density higher than the foam cell layers 3A and 3B are densely arranged.

  More specifically, the first surface coating layer 2A is a surface on the roller 21 side of the extrusion molding machine 10 described below. The foam extruded from the upper discharge port 12 is foamed to a thin skin shape by opening the upper surface in the vicinity of the discharge port 12, and then pressed from directly above by the roller 21. Therefore, the first surface coating layer 2A is thinner than the second surface coating layer 2B and is formed on a flat surface. Further, the first surface coating layer 2A is presumed to have a structure in which thin-film foam cells S2 are densely arranged. Thereby, it is estimated that the sound absorption characteristic of a porous type appears notably.

  The second surface coating layer 2B is on the mold surface 20a side of the extrusion molding machine 10 described below. The foam material pushed out from the lower discharge port 13 foams in a limited space, and slides on the mold surface 20a while being pressed from the upper surface. Therefore, the second surface coating layer 2B has a flat and rippled ripple, and is thicker and slightly harder (texture having a higher density) than the first surface coating layer 2A. In other words, since the surface is flat and the film is firm, it is presumed that the surface is easily reflected and the sound absorption effect due to resonance is easily produced.

  As shown in detail in FIGS. 3A to 3C, a large number of small holes 6, which are film fracture portions, are formed on both sides of the first surface film layer 2 </ b> A and the second surface film layer 2 </ b> B. The small holes 6 of the first surface coating layer 2A are formed at equal intervals (100 mm pitch) in the orthogonal direction. The small holes 6 of the second surface coating layer 2B are formed at equal intervals (50 mm pitch) in the orthogonal direction and shifted by 1/2 pitch in the orthogonal direction. Each hole 6 is a circular hole and has a depth that reaches the foamed cell layers 3 </ b> A and 3 </ b> B, but does not reach the partition coating layer 4. Each small hole 6 is a hole having a diameter of about 5 mm, and is not a plane but a dotted film break. The small holes 6 are formed more in the second surface coating layer 2B on the mold side than in the first surface coating layer 2A on the roller side. Note that FIG. 3C does not include cross-sectional hatching for clarity.

  Next, the extrusion molding machine 10 and the press apparatus 30 for producing the foam 1A will be described. As shown in FIGS. 4 (a), 4 (b) and 5, the extrusion molding machine 10 includes an inlet (not shown) for charging each foam material, and a kneading means (FIG. 5) for kneading the charged foam material. (Not shown), a heating means (not shown) for heating the kneaded foam material to a high temperature, a pressing means (not shown) for pressing the foam material, and a front end side of the pressing chamber are arranged to be closed. A base member 11 and a regulation frame wall 20 disposed so as to surround the outside of the base member 11 are provided. The base member 11 has a plurality of upper and lower discharge ports 12 and 13 arranged at equal intervals P1 in the horizontal direction. The upper and lower two-stage discharge ports 12 and 13 are arranged at the same position in the horizontal direction. The restriction frame wall 20 restricts the foaming region of the foam material discharged from the two-stage discharge ports 12 and 13. The regulation frame wall 20 is a flat rectangular frame.

  Further, the upper surface side of the regulation frame wall 20 is opened downstream of the regulation frame wall 20 in the pushing direction. At this opened position, a plurality of rollers 21 are provided side by side in the extrusion direction. Each roller 21 is rotatably supported so as to rotate following the extruded foam 1. Each roller 21 may be configured to rotate at the extrusion speed of the foam 1. Each roller 21 compresses the upper surface of the foam 1 to be extruded. The height of the lowermost surface of each roller 21 is set to 10 mm from the lower surface of the regulation frame wall 20. Accordingly, the foam 1 having a thickness of 10 mm is manufactured.

  As shown in FIG. 6, the press device 30 includes a fixed press body 31 and a movable press body 32 that are arranged to face each other. The movable press body 32 can move in the proximity / separation direction of the fixed press body 31.

  Next, a method for manufacturing the foam 1A will be described. A paper powder component, a polypropylene resin material, corn starch as an auxiliary agent, and water are supplied into the extrusion molding machine 10. 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 upper and lower discharge ports 12 and 13 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 the discharge ports 12 and 13, 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. As shown in FIG. 5, since this foaming is regulated by the regulation frame wall 20 and the roller 21, the foam 1 having a cross-sectional area defined by the space regulated by the regulation frame wall 20 and the roller 21 is continuously extruded. . Each of the foamed cells S1, S2, S3 has a space (air layer) formed therein without being broken by the flexibility of the paper powder component, the adhesiveness of corn starch, or the like.

  Further, the foam material discharged from each of the discharge ports 12 and 13 cannot be freely foamed, and as described above, the foam formation is suppressed by the regulation frame wall 20 and the roller 21, and the foam cells interfere with each other. This suppresses foam formation. Specifically, foam formation of the foam cell S <b> 2 located in the vicinity of the inner periphery of the restriction frame wall 20 is suppressed by the restriction frame wall 20 and the roller 21. Thereby, the first and second surface coating layers 2A and 2B are formed. In the foam cell S1 located near the middle position between the upper and lower discharge ports 12 and 13, the foam cells S1 collide (interfere) with each other, and foam formation is suppressed. Thereby, the partition coat layer 4 is formed. In the foam cell S2 located near the middle position between the discharge ports 12 (or 13) 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 works only with a weaker restraining force than the foamed cells S1 and S2. As a result, the foam cell layers 3A and 3B are formed. The foam 1 has a thickness of 10 mm by passing under the roller 21 and receiving a compression force.

  The foam 1 manufactured from the extrusion molding machine 10 is cut to a predetermined size. As shown in FIG. 6, the cut foam 1 is set in a press device 30 in a three-layer manner. The press device 30 compresses the foam 1 to about 1/10, and then releases the compression. When the compression is released, the foam 1 returns almost to its original thickness. Foam 1 that uses J830HV, a polypropylene resin material, as a synthetic tree component, has a core portion (hard portion) on the film of foamed cells S1, S2, and S3 only by extrusion production with an extrusion molding machine 10, and vibration due to sound. It is a foam structure that is difficult to break. When the foam (virgin material) 1 extruded from the extrusion molding machine 10 is once compressed and deformed, the core portion (hard portion) of the coating of the foam cells S1, S2, and S3 is destroyed, thereby forming a flexible coating. . Thereby, it is processed into the flexible foam 1 which is easy to vibrate by sound.

  Finally, a large number of small holes 6 are formed on both side surfaces of the first surface coating layer 2A and the second surface coating layer 2B of the foam 1. Thus, the foam 1A is manufactured.

  As described above, in the foam 1A configured as described above, the foam cells S1, S2, and S3 are disposed on the surface side of the foam cell layers 3A and 3B and the foam cell layers 3A and 3B, and the foam cell layers 3A and 3B. The first and second surface coating layers 2A and 2B are densely arranged with foam cells S3 having a higher foaming density. The foam cell layers 3A and 2B are disposed on both sides of the first and second surface coating layers 2A and 2B. A large number of small holes 6 reaching 3B are provided. Accordingly, since the sound incident on the foam 1A from the outside has the first or second surface coating layer 2A, 2B, the surface reflected wave reflected by the first or second surface coating layer 2A, 2B and the foam 1A are reflected. There is a transmission reflected wave that enters the interior of the filter and returns as a reflected wave. The surface reflected wave and the transmitted reflected wave cancel each other, and the sound absorption peak performance is obtained in the low frequency band due to the sound absorption characteristic due to the resonance effect.

  On the other hand, the sound incident on the foam 1A from the outside easily enters the inside because there are a large number of small holes 6 in the first or second surface coating layer 2A, 2B. The amount of absorption due to vibration energy increases, and the sound absorption characteristics in the high frequency band due to the porous type are improved as compared with the conventional foam. As described above, the sound absorption peak performance is obtained in the low frequency band, and the deterioration of the sound absorption performance in the high frequency band can be suppressed.

  The foam 1A is interposed between the foam cell layers 3A and 3B, the foam cells S1 having a higher density than the foam cell layers 3A and 3B are densely arranged, and the foam cell layers 3A and 3B are continuously arranged in a straight line. It has the partition membrane | film | coat layer 4 partitioned into. Thereby, when the vibration propagating in the foam cell layers 3A and 3B of the foam 1A reaches the partition coating layer 4, the partition coating layer 4 resets the random vibration to the plane vibration, and then further expands the foam cell layer. Since it propagates in 3A and 3B, vibration absorption is promoted by the partition coating layer 4, and it is considered that the sound absorption characteristics are improved as compared with those without the partition coating layer 4. Moreover, the sound incident on the foam from the outside includes a surface reflected wave that is reflected on the surface of the partition coating layer 4 and a transmitted reflected wave that enters the interior from the partition coating layer 4 and is reflected and returned. The sound absorption peak performance is improved because the sound absorption peak performance is obtained in the low frequency band also by such cancellation of the surface reflected wave and the transmitted reflected wave, that is, the sound absorption characteristic due to the resonance effect. In addition, the foam 1A having the partition coating layer 4 has a phase of sound when passing through the inside of the foam 1A at the partition coating layer 4 as compared with the foam without the partition coating layer 4 (conventional example). You can slow down the speed. As a result, the sound absorption peak due to the resonance effect is shifted to the low frequency side. Therefore, the low-frequency shift of the sound absorption peak, which can be achieved only by increasing the thickness of the conventional foam, can be achieved without increasing the thickness of the foam 1A of the first embodiment. In other words, the foam can adjust the frequency of the sound absorption peak depending on the presence or absence of the partition coating layer 4.

  Since the foam 1A uses J830HV as a polypropylene resin material, the first and second surface coating layers 2A and 2B are likely to vibrate with respect to a specific frequency. Thereby, a high sound absorption peak value is obtained for a specific frequency.

  FIG. 7 shows a foam (press-only foam) that has been press-processed but not surface-processed (small-hole formation), and a foam according to the first embodiment in which small-holes 6 are formed after the press-work (with small holes). It is a sound absorptivity measurement result by the reverberation room method in 1A of foams and a synthate. Each foam sample has a horizontal dimension of 100 cm, a vertical dimension of 50 cm, and a thickness dimension of 10 mm. In addition, the dimension of the sample of a foam is the same also in the following 2nd-5th embodiment.

  As shown in FIG. 7, in the foam 1A in which the small holes 6 are formed, when the sound incident side is the first surface film layer 2A (surface on the roller 21 side), the sound is incident on the second surface film layer 2B. In both cases (surface on the mold surface 20a side), it has been confirmed that it has a sound absorption peak performance in the low frequency band, and can suppress a decrease in the sound absorption performance in the high frequency band as compared with the foam only in the press. It was done.

  The foam 1A in which the small holes 6 are formed and the foam only in the press may be the first surface film layer 2A (on the roller 21 side) in the case of the second surface film layer 2B (surface on the mold surface 20a side) as the sound incident side. The sound absorption peak performance in the low frequency band is better than in the case of surface). This is presumed to be due to the difference in structure between the first surface coating layer 2A and the second surface coating layer 2B as described above. That is, the second surface coating layer 2B has a flat and rippled ripple, and is thicker and slightly harder (texture with higher density) than the first surface coating layer 2A. In other words, since the surface is flat and the film is firm, it is presumed that the surface easily reflects and the sound absorption effect due to resonance easily occurs.

  In the case of the foam 1A having the small holes 6 and the foam only in the press, the first surface coating layer 2A (the surface on the roller 21 side) is the second surface coating layer 2B (on the mold surface 20a side) as the sound incident side. The sound absorption performance in the high frequency band is better than in the case of the surface). This is presumed to be due to the difference in structure between the first surface coating layer 2A and the second surface coating layer 2B as described above. In other words, the first surface coating layer 2A is presumed to be a structure in which the thin foam cells S2 are densely arranged and a structure in which the porous sound absorption characteristic appears remarkably.

  In the foam 1A in which the small holes 6 are formed, when the sound incident side is the first surface film layer 2A (surface on the roller 21 side), the sound absorption coefficient is 0.6 over the entire frequency band of approximately 1.2 kHz or more. That's it. Therefore, it exhibits high sound absorption characteristics in a frequency band that covers most of the frequency range (1 kHz to 2 kHz) of speech intelligibility, and is suitable as a sound absorbing material used, for example, in an automobile.

  A large number of small holes 6 are provided on both sides of the first surface coating layer 2A and the second surface coating layer 2B, but they may be provided only on one side.

(Second Embodiment)
8 and 9 show a second embodiment of the present invention. The foam 1B of the second embodiment is different from that of the first embodiment only in the structure of the film breaking portion. Since the other structure is the same as that of the first embodiment, a duplicate description is omitted. The same components in the drawings are given the same reference numerals as in the first embodiment for clarification. Note that FIG. 8B does not include cross-sectional hatching for clarity.

  As shown in FIGS. 8 (a) and 8 (b), the film rupture portion is a large number of cracks 7 formed in each of the first surface film layer 2A and the second surface film layer 2B. The crack 7 was formed by applying a local pressing (compression force) over the entire area of the first surface coating layer 2A and the second surface coating layer 2B, and this local pressing. Unlike the first embodiment, the cracks 7 are formed at irregular positions.

  Also in the second embodiment, for the same reason as in the first embodiment, the sound absorption peak performance is provided in the low frequency band, and the deterioration of the sound absorption performance in the high frequency band can be suppressed.

  FIG. 9 shows a foam (press-only foam) that has not been subjected to surface processing (crack formation) just by pressing, and a foam (cracked foam) 1B according to the second embodiment in which a crack 7 is formed after pressing. And a sound absorption coefficient measurement result by a reverberation chamber method in a synthesizer.

  As shown in FIG. 9, in the foam 1 </ b> B in which the crack 7 is formed, when the sound incident side is the first surface coating layer 2 </ b> A (the surface on the roller 21 side), the sound incidence is the second surface coating layer 2 </ b> B ( In the case of the mold surface 20a side), it is confirmed that it has a sound absorption peak performance in the low frequency band and can suppress a decrease in the sound absorption performance in the high frequency band as compared with the foam only in the press. It was. The sound absorption peak value in the low frequency band was improved as compared with the foam only in the press. This is presumably because the foam 1B, particularly the first and second surface coating layers 2A and 2B, vibrate sensitively to sound by local pressing. The sound absorption performance in the high frequency band was only slightly improved compared with the foam only for the press. This is presumably because the foam 1B, in particular, the foam cell S3 of the foam cell layers 3A and 3B, is easily vibrated by sound by local pressing.

  In the case of the foam 1B and the press-only foam in which the crack 7 is formed, the case where the second surface coating layer 2B (surface on the mold surface 20a side) is used as the sound incident side is the first surface coating layer 2A (surface on the roller 21 side). The sound absorption peak performance in the low frequency band is better than in the case of). As described in the first embodiment, this is presumed to be due to the difference in structure between the first surface coating layer 2A and the second surface coating layer 2B.

  In the case of the foam 1B and the press-only foam in which the crack 7 is formed, the surface of the first surface coating layer 2A (surface on the roller 21 side) is the second surface coating layer 2B (surface on the mold surface 20a side) as the sound incident side. The sound absorption performance in the high frequency band is better than in the case of). As described in the first embodiment, this is presumed to be due to the difference in structure between the first surface coating layer 2A and the second surface coating layer 2B.

  In the foam 1 </ b> B in which the crack 7 is formed, when the sound incident side is the first surface coating layer 2 </ b> A (surface on the roller 21 side), the sound absorption coefficient is 0.6 or more over the entire frequency band of approximately 1.2 kHz or more. It is. Therefore, it exhibits high sound absorption characteristics in a frequency band that covers most of the frequency range (1 kHz to 2 kHz) of speech intelligibility, and is suitable as a sound absorbing material used, for example, in an automobile.

  In the second embodiment, the crack 7 is formed by local press working on the first and second surface coating layers 2A and 2B, but may be formed by irregularly cutting with a cutter, regardless of the production method. Absent. However, when formed by local pressing as in the second embodiment, the structure can easily be vibrated by sound by further softening the foam 1B as described above, and the sound absorption performance is improved. .

  Although many cracks 7 are provided on both sides of the first surface coating layer 2A and the second surface coating layer 2B, they may be provided only on either one side.

(Third embodiment)
10 and 11 show a third embodiment of the present invention. The foam 1C of the third embodiment is different from that of the first embodiment only in the structure of the film rupture portion. Since the other structure is the same as that of the first embodiment, a duplicate description is omitted. The same components in the drawings are given the same reference numerals as in the first embodiment for clarification. Note that FIG. 10B does not include cross-sectional hatching for clarity.

  As shown in FIGS. 10 (a) and 10 (b), the film fracture portion is a large number of cuts 8 formed in the first surface film layer 2A. The cuts 8 are formed at equal intervals (about 50 mm pitch) in the direction perpendicular to the extrusion direction. The notch 8 has a depth that reaches the foamed cell layer 3 </ b> A but does not reach the partition coating layer 4. The notch 8 is not formed in the second surface coating layer 2B.

  Also in the third embodiment, for the same reason as in the first embodiment, the sound absorption peak performance is provided in the low frequency band, and the deterioration of the sound absorption performance in the high frequency band can be suppressed.

  FIG. 11 shows a foam (cut foam) 1C according to a third embodiment in which a foam (press only foam) that has been subjected to press working but not surface-treated (cut formed) and a cut 8 formed after the press working are shown. And a sound absorption coefficient measurement result by a reverberation chamber method in a synthesizer.

  As shown in FIG. 11, when the sound incident side is the first surface film layer 2A (surface on the roller 21 side), the foam 1C in which the cuts 8 are formed has a sound absorption peak performance in a low frequency band, Moreover, it was confirmed that the deterioration of the sound absorption performance in the high frequency band can be suppressed as compared with the foam only in the press. In the foam 1C in which the cuts 8 are formed, when the sound incident side is the first surface film layer 2A (surface on the roller 21 side), the sound absorption peak value is slightly improved as compared with the foam only in the press.

  In the case of the foam 1C and the press-only foam in which the cuts 8 are formed, the case of the second surface coating layer 2B (surface on the mold surface 20a side) as the sound incident side is the first surface coating layer 2A (surface on the roller 21 side) The sound absorption peak performance in the low frequency band is better than in the case of). As described in the first embodiment, this is presumed to be due to the difference in structure between the first surface coating layer 2A and the second surface coating layer 2B.

  In the case of the foam 1C and the press-only foam in which the cuts 8 are formed, the surface of the first surface coating layer 2A (the surface on the roller 21 side) is the second surface coating layer 2B (the surface on the mold surface 20a side). The sound absorption performance in the high frequency band is better than in the case of). As described in the first embodiment, this is presumed to be due to the difference in structure between the first surface coating layer 2A and the second surface coating layer 2B.

  In the foam 1C in which the cuts 8 are formed, when the sound incident side is the first surface coating layer 2A (surface on the roller 21 side), the sound absorption coefficient is 0.64 or more over the entire frequency band of approximately 1.2 kHz or more. It is. Therefore, it exhibits high sound absorption characteristics in a frequency band that covers most of the frequency range (1 kHz to 2 kHz) of speech intelligibility, and is suitable as a sound absorbing material used, for example, in an automobile.

  When the sound incident side was the second surface coating layer 2B (surface on the mold surface 20a side), no cut was formed, so that only the press had sound absorption characteristics equivalent to the foam. If the notch 8 is formed also in the 2nd surface coating layer 2B, it can be estimated that the same effect as the 1st surface coating layer 2A is acquired.

  In this 3rd Embodiment, although the cut 8 was formed in the direction orthogonal to an extrusion direction, you may form it in directions other than this. The cut may be a curved line instead of a straight line.

(Fourth embodiment)
12 and 13 show a fourth embodiment of the present invention. The foam 1D of the fourth embodiment is different from that of the first embodiment only in the structure of the film breakage portion. Since the other structure is the same as that of the first embodiment, a duplicate description is omitted. The same components in the drawings are given the same reference numerals as in the first embodiment for clarification. Note that FIG. 12B does not include cross-sectional hatching for clarity.

  As shown in FIGS. 12 (a) and 12 (b), the film rupture portion is a crack 7 and a large number of cuts 8 formed in the first surface film layer 2A. The crack 7 has the same configuration as in the second embodiment, and the manufacturing method is also the same. The notch 8 has the same configuration as that of the third embodiment, and the manufacturing method is also the same. Neither the crack 7 nor the notch 8 is formed in the second surface coating layer 2B.

  Also in the fourth embodiment, for the same reason as in the first embodiment, the sound absorption peak performance is provided in the low frequency band, and the deterioration of the sound absorption performance in the high frequency band can be suppressed.

  FIG. 13 shows a foam (press-only foam) that is not subjected to surface processing (formation of cracks 7 and notches 8), and a foam (notched foam) 1C in which notches 8 are formed after pressing, It is a sound absorption coefficient measurement result by the reverberation chamber method in the foam (crack / cut foam) 1D according to the fourth embodiment in which the crack 7 and the cut 8 are formed after the press working, and the synthalate.

  As shown in FIG. 13, the foam 1 </ b> D in which the crack 7 and the notch 8 are formed has the sound incident side as the first surface coating layer 2 </ b> A (the surface on the roller 21 side) as the sound incident side. In the case of the coating layer 2A (the surface on the roller 21 side), the sound absorption performance is reduced in the high frequency band as compared with the foam 1C having the sound absorption peak performance in the low frequency band and having the notch 8 formed. It was confirmed that can be further suppressed. This is presumably because the sound is more likely to enter the interior than the foam 1C in which the notches 8 are formed, and the amount of sound entering is increased.

  In the foam 1D in which the crack 7 and the notch 8 are formed, when the sound incident side is the first surface coating layer 2A (surface on the roller 21 side), the sound absorption coefficient is 0 in the entire frequency band of approximately 1.2 kHz or more. .66 or more. Therefore, it exhibits high sound absorption characteristics in a frequency band that covers most of the frequency range (1 kHz to 2 kHz) of speech intelligibility, and is suitable as a sound absorbing material used, for example, in an automobile.

  When the sound incident side is the second surface coating layer 2B (the surface on the mold surface 20a side), since the notch 8 is not formed, it is estimated that only the press has sound absorption characteristics equivalent to the foam. it can. Moreover, if the crack 7 and the notch 8 are formed also in the 2nd surface coating layer 2B, it can be estimated that the same effect as the 1st surface coating layer 2A side is acquired.

(Fifth embodiment)
14 and 15 show a fifth embodiment of the present invention. The foam 1E of the fifth embodiment is different from that of the first embodiment only in the structure of the film breakage portion. Since the other structure is the same as that of the first embodiment, a duplicate description is omitted. The same components in the drawings are given the same reference numerals as in the first embodiment for clarification. Note that FIG. 14B does not include cross-sectional hatching for clarity.

  As shown in FIGS. 14A and 14B, the film breakage portions are a large number of cuts 8 in the cross direction formed in the first surface film layer 2 </ b> A. The cuts 8 are formed at equal intervals (about 50 mm pitch) in the same direction as the extrusion direction and in the vertical direction thereof. The notch 8 has a depth that reaches the foamed cell layer 3 </ b> A but does not reach the partition coating layer 4. The notch 8 is not formed in the second surface coating layer 2B.

  Also in the fifth embodiment, for the same reason as in the first embodiment, the sound absorption peak performance is provided in the low frequency band, and the deterioration of the sound absorption performance in the high frequency band can be suppressed.

  FIG. 15 shows a foam (press-only foam) that has not been surface-processed (cut-formed) only after being pressed, a foam (cut-cut foam) 1C in which a cut 8 in one direction is formed after pressing, It is a sound absorption coefficient measurement result by the reverberation chamber method in the foam (cross cut foam) 1E which concerns on 5th Embodiment which formed the cut 8 of the cross direction after a process, and a synthate.

  As shown in FIG. 15, the foam 1E formed with the cut 8 in the cross direction has a sound absorption peak performance in a low frequency band when the sound incident side is the first surface coating layer 2A (the surface on the roller 21 side). In addition, it was confirmed that the deterioration of the sound absorption performance in the high frequency band can be further suppressed as compared with the foam 1C in which the cut 8 in one direction is formed. This is presumed to be because the sound is more likely to enter the interior as compared with the foam 1C in which the cut 8 in one direction is formed.

  The foam 1E in which the cut 8 in the cross direction is formed is compared with the foam 1C in which the cut 8 in one direction is formed when the sound incident side is the first surface coating layer 2A (surface on the roller 21 side). The sound absorption peak value was slightly improved.

  In the foam 1E in which the cut 8 in the cross direction is formed, when the sound incident side is the first surface coating layer 2A (surface on the roller 21 side), the sound absorption coefficient is 0 over the entire frequency band of approximately 1.2 kHz or more. .69 or more. Therefore, it exhibits high sound absorption characteristics in a frequency band that covers most of the frequency range (1 kHz to 2 kHz) of speech intelligibility, and is suitable as a sound absorbing material used, for example, in an automobile.

  When the sound incident side is the second surface coating layer 2B (surface on the mold surface 20a side), no notch is formed, so it can be estimated that the sound absorption characteristic is equivalent to that of the foam only in the press. . If the cut 8 in the cross direction is formed also in the second surface coating layer 2B, it can be estimated that the same effect as the first surface coating layer 2A side can be obtained.

  In this fifth embodiment, the incision 8 is formed in the extrusion direction and in a direction orthogonal to the extrusion direction, but may be formed in a direction other than this, or may be in a direction other than orthogonal, and further in three or more directions. You may form in the direction which crosses.

(About the film fracture portion of the first to fifth embodiments)
FIG. 16 collectively shows the sound absorption characteristics of the foam and the cinsalate according to each of the above embodiments. Thus, it is speculated that if the sound intrusion into the foam is improved, it is possible to effectively suppress the deterioration of the sound absorption characteristics in a frequency band (approximately 2 kHz or more) higher than the frequency band that exhibits the sound absorption characteristics due to the resonance effect. it can.

(Sixth embodiment)
17 and 18 show a sixth embodiment of the present invention. The foam 1F of the sixth embodiment is different from that of the first embodiment only in the structure of the film breaking portion. Since the other structure is the same as that of the first embodiment, a duplicate description is omitted. The same components in the drawings are given the same reference numerals as in the first embodiment for clarification. In FIG. 17B, only the portions of the first and second surface coating layers 2A and 2B are cross-sectionally hatched for clarity.

  As shown in FIGS. 17 (a) and 17 (b), the film breakage part is a peeling part 9 in which a part of the first surface film layer 2A is peeled off in a planar shape. The stripping portions 9 are arranged in a lattice pattern on the first surface coating layer 2A. The stripped portion 9 is not formed on the second surface coating layer 2B.

  Also in the sixth embodiment, for the same reason as in the first embodiment, the sound absorption peak performance is provided in the low frequency band, and the deterioration of the sound absorption performance in the high frequency band can be suppressed.

  FIG. 18 shows a foam (cross-cut foam) 1E in which cross-direction cuts 8 are formed after pressing, and a foam (grid-shaped) according to a sixth embodiment in which grid-like peeling portions 9 are formed after press processing. It is a sound absorptivity measurement result by the reverberation chamber method in the peeled foam) 1F and the synthalate. The sample of the foam 1F in which the grid-like peeled portions 9 are formed has a lateral dimension of 200 cm, a longitudinal dimension of 10 cm, and a thickness dimension of 10 mm.

  As shown in FIG. 18, the 1F formed with the grid-like stripping portion 9 has a sound absorption peak performance in a low frequency band when the sound incident side is the first surface film layer 2A (the surface on the roller 21 side). In addition, it was confirmed that a decrease in sound absorption performance in a high frequency band can be suppressed.

  In addition, the foam 1F in which the grid-like stripped portions 9 are formed can further suppress the deterioration of the sound absorption characteristics in the high frequency band as compared with the foam 1E in which the cross-direction cuts 8 are formed. This is presumably because the foam 1F in which the grid-like stripping portions 9 are formed has the foam cell layer 3A exposed on the surface, and the amount of sound entering the foam 1F has increased. .

  In the foam 1F in which the lattice-shaped stripped portions 9 are formed, the frequency of the sound absorption peak due to the resonance effect shifts to the high frequency side as compared with the foam 1E in which the cross-direction cuts 8 are formed. This is presumably because the peeled area of the first surface coating layer 2A was increased and the total thickness was reduced. The foam 1F in which the grid-like peeled portions 9 are formed has substantially the same sound absorption peak value due to the resonance effect as compared with the foam 1E in which the cross-direction cuts 8 are formed. This is considered to be because the first surface coating layer 2A was peeled off in a lattice shape but maintained the skin effect.

  In the foam 1F in which the grid-like peeled portions 9 are formed, when the sound incident side is the first surface film layer 2A (the surface on the roller 21 side), the sound absorption coefficient is almost in the entire frequency band of 1.3 kHz or more. Is 0.72 or more. Therefore, it exhibits high sound absorption characteristics in a frequency band that covers most of the frequency range (1 kHz to 2 kHz) of speech intelligibility, and is suitable as a sound absorbing material used, for example, in an automobile.

  In addition, if the grid-like peeling part 9 is formed also in the 2nd surface coating layer 2B, it can be estimated that the same effect as the 1st surface coating layer 2A side is acquired.

(Seventh embodiment)
19 and 20 show a seventh embodiment of the present invention. The foam 1G of the seventh embodiment is different from that of the first embodiment only in the structure of the film rupture portion. Since the other structure is the same as that of the first embodiment, a duplicate description is omitted. The same components in the drawings are given the same reference numerals as in the first embodiment for clarification. In FIG. 19 (b), only the portions of the first and second surface coating layers 2A and 2B are hatched for the sake of clarity.

  As shown in FIGS. 19 (a) and 19 (b), the film rupture portion is a stripped portion 9a obtained by stripping a part of the first surface coating layer 2A into a planar shape. The stripped portions 9a are arranged in stripes on the first surface coating layer 2A. The stripped portion 9a is not formed on the second surface coating layer 2B.

  Also in the seventh embodiment, for the same reason as in the first embodiment, the sound absorption peak performance is provided in the low frequency band, and the deterioration of the sound absorption performance in the high frequency band can be suppressed.

  FIG. 20 shows a foam (cross-cut foam) 1E in which cross-direction cuts 8 are formed after pressing, and a foam (lattice-stripped foam) 1F in which lattice-shaped stripping portions 9 are formed after press processing. And, it is a sound absorption coefficient measurement result by a reverberation chamber method in a foam (striped stripped foam) 1G according to the seventh embodiment in which striped stripped portions 9a are formed after press working and a synthalate. The sample of the foam 1G in which the striped stripped portion 9a is formed has a horizontal dimension: 200 cm, a vertical dimension: 10 cm, and a thickness dimension of 10 mm.

  As shown in FIG. 20, the foam 1G having the stripped strip 9a has a sound absorption peak in the low frequency band when the sound incident side is the first surface film layer 2A (the surface on the roller 21 side). It has been confirmed that it has performance and can suppress a decrease in sound absorption performance in a high frequency band.

  In addition, the foam 1G in which the striped stripped portions 9a are formed was able to further suppress the deterioration of the sound absorption characteristics in the high frequency band as compared with the foam 1F in which the grid-shaped stripped portions 9 were formed. . This is because the foam 1F in which the striped stripped portions 9a are formed has an increased exposed area of the foam cell layer 3A compared to the foam 1F in which the grid-shaped stripped portions 9 are formed. This is presumed to be because the amount of sound entering the interior of the slab increased further.

  In the foam 1G in which the striped stripped portion 9a is formed, the frequency of the sound absorption peak due to the resonance effect slightly shifts to the high frequency side as compared with the foam 1F in which the lattice-shaped stripped portion 9 is formed. This is presumably because the peeled area of the first surface coating layer 2A was increased and the total thickness was reduced.

  The foam 1G in which the striped stripped portions 9a are formed has a slightly lower sound absorption peak value due to the resonance effect than the foam 1F in which the grid-shaped stripped portions 9 are formed. This is presumably because the skin effect of the first surface coating layer 2A was maintained, but the skin effect of the first surface coating layer 2A was reduced by the increase in the peeled area.

  In the foam 1G in which the striped stripped portion 9a is formed, when the sound incident side is the first surface coating layer 2A (the surface on the roller 21 side), the sound absorption coefficient is obtained over the entire frequency band of approximately 1.5 kHz or more. Is 0.77 or more. Therefore, a very high sound absorption characteristic is exhibited in a frequency band covering half of the frequency range (1 kHz to 2 kHz) of speech intelligibility. For example, it can be used as a sound absorbing material used in an automobile.

  In addition, if the striped stripping part 9a is formed also in the 2nd surface coating layer 2B, it can be estimated that the same effect as the 1st surface coating layer 2A side is acquired.

(Modification)
In each of the above-described embodiments, the film rupture portion is formed by the small hole 6, the crack 7, the notch 8, and the stripping portions 9 and 9a. However, the present invention is not limited to this, and the first surface film layer 2A is not limited thereto. Or the 2nd surface membrane | film | coat layer 2B should just be a form which fractures | ruptures even a little and increases the internal approach of a sound. The film rupture portion has a depth that reaches the foamed cell layers 3 </ b> A and 3 </ b> B, but does not reach the partition film layer 4. In the sixth and seventh embodiments, the stripping portions 9 and 9a have a lattice shape or a striped shape, but the shape is any shape that strips the first surface coating layer 2A and the second surface coating layer 2B into a planar shape. It doesn't matter.

  In each embodiment, the foams 1 </ b> A to 1 </ b> G have the partition coating layer 4 inside, but may not have the partition coating layer 4. Further, it may have a plurality of partition coating layers 4. A further sound absorbing effect by the partition coating layer 4 can be expected.

  In each embodiment, the synthetic resin component uses a polypropylene resin material J830HV (a kind of product name Prime Polypro of Prime Polymer Co., Ltd.), but other materials (polypropylene resins J3000GP, J2000GP, J2003GP, J2041GA). (Both are one of Prime Polymer's trade name Prime Polypro), etc., and have sound absorption peak performance in the low frequency band (approximately 1 kHz to 2 kHz), and in the high frequency band (approximately 2 kHz or more). Decrease in sound absorption performance can be suppressed.

1A to 1G Foam 2A First surface film layer 2B Second surface film layer 3A, 3B Foamed cell layer 4 Partition film layer 6 Small hole (film breakage part)
7 Crack (film breakage)
8 notch (film breakage)
9, 9a Stripped part (film rupture part)
S1, S2, S3 Foamed cells

Claims (10)

A foam comprising a foam cell in which a pulp fiber component, a synthetic resin component, and a starch component as an auxiliary agent are foamed, and a large number of spaces are formed,
The foamed cell is disposed between the foamed cell layer, the foamed cell layer, a surface film layer in which foamed cells having a foaming density higher than the foamed cell layer are densely arranged, and the foamed cell layer. The foamed cell layer and the partition coating layer in which the foam cells having a foam density higher than each surface coating layer are densely arranged are configured in the thickness direction, and the partition coating layer is continuously formed between the plurality of foam cell layers. Partition,
A foam having a film rupture portion reaching the foam cell layer on at least one of the surface film layers. The foam according to claim 1,
The film rupture portion is a foam having a large number of small holes. The foam according to claim 1 or 2,
The film rupture portion is a foam having a large number of cracks. The foam according to any one of claims 1 to 3,
The foam is characterized in that the film breakage part is a large number of cuts. The foam according to claim 4,
The said cut | incision is provided along the same direction, The foam characterized by the above-mentioned. The foam according to claim 4,
The foam is characterized in that the cut is provided along a plurality of directions. The foam according to any one of claims 1 to 4,
The foam is characterized in that the film rupture part is a peeled part obtained by peeling off a part of the surface film layer in a planar shape. The foam according to claim 7,
The foam according to claim 1, wherein the stripping portion is provided in a lattice pattern on the surface coating layer. The foam according to claim 7,
The foamed body, wherein the stripping portion is provided in a striped pattern on the surface film layer. The foam according to any one of claims 1 to 9,
The synthetic resin component is a polypropylene resin material J830HV (a kind of product name Prime Polypro of Prime Polymer Co., Ltd.).

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