JP2793570B2 - Ceramic sound absorbing material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound-absorbing material made of ceramics which has excellent weather resistance and can be used even at high temperatures or high-speed airflow.

[0002]

2. Description of the Related Art Sound-absorbing materials constituting soundproof walls of roads, railways and the like are used by humans as 400-400.
Sound absorption in the frequency range of 0 Hz is required.
There is a particular need for sound absorption in the frequency range of ２０００2000 Hz.

As a conventional sound absorbing material, a mineral fiber based sound absorbing material such as glass wool or rock wool has been typical. However, the mineral fiber-based sound absorbing material has a significant decrease in sound absorbing performance when it contains water, and is deformed with the passage of time because it is made of fibers, and is easily scattered or peeled off by a high-speed air current, and the resin as a binder is deteriorated by ultraviolet rays. Due to its drawbacks, it cannot be used outdoors as it is, and is unsuitable as a soundproof wall for roads, railways and the like. In order to use these mineral fiber-based sound absorbing materials outdoors, it is necessary to cover them with a resin film and store them in a metal container, so that the cost is extremely high.

[0004] A sound absorbing material having a large number of through holes in a gypsum board is also well known. Since the sound-absorbing material made of this perforated gypsum board has no sound absorbing performance in the gypsum board and absorbs sound energy by resonance in the through-hole,
There was a disadvantage that only a specific frequency could be absorbed. In order to solve this defect, an air layer is provided on the back, or a backing material such as glass wool is attached to the back. However, these methods have a problem in that the construction is troublesome.

Recently, ceramic or cement-based sound absorbing materials have been developed as sound absorbing materials which are excellent in weather resistance, can be used outdoors, and are nonflammable and have a heat insulating effect. For example, ceramic-based sound-absorbing materials consist of ceramic blocks formed by molding ceramic raw materials and firing at high temperatures.
Because it is porous, its fine pores have the effect of absorbing sound energy.

[0006]

The sound-absorbing material made of a porous ceramic block has excellent weather resistance as described above. Therefore, the sound-absorbing material is arranged side by side in a length direction and a width direction to construct a soundproof wall for a road or a railway. Building has been done. In this case, a rigid wall that supports each ceramic block is usually provided behind the soundproof wall. There are a method of closely contacting the back surface of the ceramic block and the rigid wall, and a method of providing an air layer therebetween.

However, the conventional sound absorbing material made of a porous ceramic block cannot be said to have a sufficient sound absorbing coefficient.
Further, since actual noise from roads and railways enters from various directions and angles, a satisfactory sound absorbing effect cannot always be obtained. Further, since the conventional sound absorbing material is a ceramic block as it is, when a soundproof wall is constructed, the sound absorbing material is often inferior in design.

The present invention has been made in view of such a conventional situation,
It consists of a porous ceramic block with weather resistance,
It has excellent sound absorption in the frequency range of 400-4000Hz, which is considered loud by humans, and has an excellent sound absorbing effect on sounds incident from various directions and angles, such as road and railroad noise, and also has good design. An object is to provide an excellent ceramic sound absorbing material.

[0009]

Means for Solving the Problems In order to achieve the above-mentioned object, a ceramic sound-absorbing material provided by the present invention has a continuous pore having a pore diameter mainly of 0.2 to 2000 μm, a porosity of 60% or more, The air permeability is 1cm ³・ cm / cm ²・ sec ・
consists cm H ₂ O or more ceramic blocks, the perpendicular one side in the thickness direction, characterized in that a non-through groove above depth 20mm so that the opening ratio of 9% or more.

In the above-described ceramic sound-absorbing material of the present invention, non-through grooves having a groove width of 2 to 50 mm are provided at substantially equal intervals in an opening ratio of 9 to 65%, and sound absorption in a frequency range of 100 to 2000 Hz. The maximum value of the ratio is 0.8 or more.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The ceramic block used in the present invention has continuous pores having a pore size of 0.2 to 2000 μm, a porosity of 60% or more, and a permeability of 1c.
It is a porous ceramic block of m ³ · cm / cm ² · sec · cmH ₂ O or more. Such a porous ceramic block has excellent weather resistance, durability, fire resistance, and the like, and also has a large number of small continuous air holes, so that the porous ceramic block itself already has some excellent sound absorbing performance.

[0012] Such a porous ceramics block is prepared by adding a pore-forming material such as expanded polystyrene particles, foam, and wood chips to refractory clay and / or refractory chamotte, and further adding water glass or feldspar as required. It can be manufactured by mixing an inorganic binder, molding, and firing at a high temperature of about 1000 to 1700 ° C.
When foamed polystyrene particles are used, it is preferable to mix bubbles formed by mixing a surfactant at the same time.

The permeability of the porous ceramic block can be changed depending on the kind and particle size of the pore-imparting material, the firing conditions, and the like, but in order to obtain a desired sound absorbing performance, at least 1 cm ³ · cm / cm ² · sec. -Air permeability of cmH ₂ O is required. The higher the air permeability, the better the sound absorption performance. However, the upper limit of the air permeability of the ceramic block obtained by the above method is about 20 cm ³ · cm / cm ² · sec · cmH ₂ O. In the ceramic block obtained by the above method, when the porosity is less than 60%, the air permeability is reduced to 1 cm ³ · c.
It is difficult to set m / cm ² · sec · cmH ₂ O or more.
If the porosity exceeds 90%, it becomes difficult to obtain the strength required for handling and processing.
A range of ~ 90% is preferred.

In the present invention, by forming a non-penetrating groove in the porous ceramic block, a ceramic sound-absorbing material whose sound absorbing performance is further improved can be obtained. In addition, the unevenness is formed on the surface of the sound absorbing material by the non-penetrating groove, so that the surface area is increased, and the sound projecting obliquely from the side surface protruding from the bottom surface of the non-penetrating groove can be reflected in the groove. The ceramic sound-absorbing material of the present invention exhibits high sound-absorbing performance against noise from various angles and directions.

The shape and number of the non-penetrating grooves, the way of arrangement and the direction are not particularly limited. For example, as shown in FIG.
A plurality of non-through grooves 2 can be regularly arranged on one surface of the porous ceramic block 1 in directions parallel to each other. In addition, as shown in FIG. 2, a plurality of non-through grooves 2 may be regularly arranged on one surface of the porous ceramic block 1 so as to cross each other at right angles or at other angles.

In FIGS. 1 and 2, the non-through groove 2 is exemplified.
Is illustrated, but the number of non-through grooves 2 may be one or three or more as long as the aperture ratio is 9% or more as described later. The non-through groove 2 of the present invention has a slit-like elongated shape. However, as shown in FIG. Is simple and preferred. Further, the angle at which the edge of the porous ceramic block 1 intersects the non-through groove 2 is not limited to a right angle as shown in FIGS.

The ceramic sound-absorbing material of the present invention having such a non-penetrating groove 2 has a pattern formed by the non-penetrating groove 2 on the surface of the sound-insulating wall when a large number of these materials are combined to form a soundproof wall or the like for a road or a railway. Therefore, a soundproof wall having excellent design properties can be constructed by a combination method.

Unless the opening ratio of the non-through groove is at least 9%, the effect of increasing the sound absorption of the ceramic block cannot be obtained. In particular, in order to obtain a value of 0.8 or more as the maximum sound absorption coefficient in the frequency range of 100 to 2000 Hz, the aperture ratio is preferably 9 to 65%, and preferably 15 to 40%.
Is more preferred. The aperture ratio at which a value of 0.8 or more is obtained as the highest value of the sound absorption coefficient in the frequency range of 100 to 2000 Hz exists on the lower aperture ratio side as the groove width of the non-through groove is smaller,
The larger the groove width, the higher the aperture ratio. Also, when the aperture ratio is increased, the sound absorption peak frequency tends to move to the high frequency side.

If the depth of the non-through groove is 10 mm or more, the sound absorption of the ceramic block can be increased.
By setting the depth to 20 mm or more, a more remarkable improvement in the sound absorption coefficient can be achieved. Also, the sound absorption peak frequency changes by changing the depth of the non-penetrating groove, and the sound absorption peak frequency moves to the lower frequency side as the groove depth increases. The groove depths may all be the same, or may be different for each groove. When grooves having different depths are provided, the sound absorption coefficient at the sound absorption peak frequency is slightly lower than that at the same depth, but the sound absorption coefficient is improved as a whole in a wide frequency range centered on the sound absorption peak frequency.

In the sound-absorbing material of the present invention in which a non-through groove is provided, the thickness of the groove (the thickness from the groove bottom to the opposite surface of the ceramic block) is changed according to the thickness and the groove depth of the ceramic block. It is possible. By changing the back thickness, the sound absorption coefficient on the lower frequency side than the sound absorption peak frequency can be changed, that is, the sound absorption coefficient on the lower frequency side than the sound absorption peak frequency can be increased as the back thickness increases.

However, considering the effect of improving the sound absorption coefficient,
The air permeability of the ceramic block is 1 to 20 cm ³ · cm /
In the range of cm ² · sec · cm H ₂ O, there is an optimum value for the back thickness. That is, the air permeability is 1 to ⁷ cm ³ · cm / cm
30 to 50 mm in the range of ² · sec · cmH ₂ O, 50 to 80 mm in the range of 7 to 14 cm ³ · cm / cm ² · sec · cm H ₂ O, and 14 to ₂₀ cm ³ · cm / cm ² · s
In the range of ec · cmH ₂ O, the sound absorption coefficient on the low frequency side is improved in the range of 80 to 120 mm. On the other hand, if the thickness is more than this, the effect of improving the sound absorption coefficient decreases.

The width of the non-through groove is 2 mm in workability.
More preferably, the effect of increasing the sound absorption of the ceramic block in a wide frequency range is obtained when the groove width is 2 mm or more. In particular, in order to obtain a value of 0.8 or more as the highest value of the sound absorption coefficient in the frequency range of 100 to 2000 Hz, the groove width of the non-through groove is preferably in the range of 2 to 50 mm, and more preferably in the range of 5 to 15 mm. .

The sound absorption coefficient according to the present invention is based on JIS A
This was measured by a method of measuring a normal incidence sound absorption coefficient of a building material by a 1405 in-pipe method. The permeability of the ceramic block was measured in accordance with JIS R 2115,
The values are not multiplied by the kinematic viscosity of air.

[0024]

EXAMPLE 1 Sawdust as a pore-imparting material was mixed with refractory clay and refractory chamotte, molded, and fired at 1300 ° C. The obtained ceramic block is porous, having a main pore size of 0.2 to 2000 μm, a bulk specific gravity of 0.80, a porosity of 70%, and a permeability of 3.7 cm ³ · cm / cm ^2.・ Se
c · cmH ₂ O.

On a surface perpendicular to the thickness direction of the porous ceramic block having a thickness of 65 mm, non-through grooves having a groove width of 9.4 mm are formed on 10 mm, 20 mm, 30 mm, 40 mm,
At a depth of 50 mm and at a depth of 60 mm, they were arranged in parallel at substantially equal intervals with a pitch of 30 mm so that the aperture ratio became 31%.

For each of the obtained ceramic sound absorbing materials,
The sound absorption coefficient in the frequency range of 100 to 2000 Hz was measured, and the result is shown in FIG. 3 together with the sound absorption coefficient of the ceramic block having no non-through groove. As can be seen from FIG. 3, it is possible to improve the sound absorption coefficient of the ceramic block by forming the non-penetrating groove, and in particular, by setting the groove depth to 20 mm or more, 100 to 20 mm.
In the range of 00 Hz, a sound absorbing material having a maximum sound absorbing coefficient exceeding 0.8 was obtained.

Example 2 Using the same porous ceramic block as in Example 1 above, a non-through groove having a groove width of 9.4 mm and a groove depth of 40 mm was formed on one surface perpendicular to the thickness direction, and the opening ratio was 10%. , 13.4
%, 23.5%, 31.3%, 47%, and 62.7%, and were arranged in parallel at substantially equal intervals with different pitches.

For each of the obtained ceramic sound absorbing materials,
The sound absorption coefficient in the frequency range of 100 to 2000 Hz was measured, and the results are shown in FIG. From FIG. 4, the aperture ratio 9
%, Excellent sound absorption is obtained, and particularly, sound absorption in the range of 15 to 40% is more excellent.

The sound absorbing material having an aperture ratio of 62.7% is 100
Although the maximum value of the sound absorption coefficient in the range of up to 2000 Hz does not exceed 0.8, the sound absorption coefficient exceeds 0.8 in the frequency range exceeding 2000 Hz, judging from the tendency of the graph showing the sound absorption coefficient in FIG. That can be predicted.

Example 3 Using the same porous ceramic block as in Example 1 above, a non-through groove having a groove width of 2.7 mm and a groove depth of 40 mm was formed on one surface perpendicular to the thickness direction, and the aperture ratio was 6. 8%, 9%,
The pitches were changed so as to be 13.5%, 27%, and 54%, and were arranged in parallel at substantially equal intervals.

For each of the obtained ceramic sound absorbing materials,
The sound absorption coefficient in the frequency range of 100 to 2000 Hz was measured, and the results are shown in FIG. As can be seen from FIG. 5, an excellent sound absorption coefficient was obtained except for the case where the aperture ratio was 6.8%. In particular, when the opening ratio was 13.5% and 27%, a more excellent sound absorption coefficient was obtained. .

Example 4 Using the same porous ceramic block as in Example 1 above, a non-penetrating groove having a groove width of 50 mm and a groove depth of 40 mm was formed on one surface perpendicular to the thickness direction to have an opening ratio of 65%. As described above, they are arranged in parallel at substantially equal intervals with a pitch of 76 mm. In addition, non-through grooves having a groove width of 55 mm and a groove depth of 40 mm are arranged in parallel at substantially equal intervals at a pitch of 77 mm on one surface of the same porous ceramic block so as to have an opening ratio of 71.3%. Was.

For each of the obtained ceramic sound absorbing materials,
The sound absorption coefficient in the frequency range of 100 to 2000 Hz was measured, and the results are shown in FIG. As can be seen from FIG.
In the sound absorbing material having a groove width of 50 mm and an aperture ratio of 65%, the sound absorption peak is on the high frequency side near 2000 Hz, but the maximum value of the sound absorption coefficient exceeds 0.8, but the groove width of 55 mm and the aperture ratio of 71.3. % Of the sound absorbing material did not exceed 0.8 in the range of 100 to 2000 Hz.

[0034]Example 5  Sawdust as a pore-imparting material for refractory clay and refractory chamotte
After mixing, molding and firing at 1300 ° C
The pore size is mainly 0.2-2000 μm, and the bulk specific gravity
Is 1.0, porosity is 63%, air permeability is 1.1cm^Three・ Cm /
cm^Two・ Sec ・ H_TwoMade porous ceramic block of O
Built.

Further, foamed polystyrene having a particle size of 0.5 to 2 mm is mixed with refractory clay and refractory chamotte as a pore-imparting material, foamed, and then baked at 1320 ° C. so that the main component of the pore size is 0.5. 2 to 2000 μm, bulk specific gravity 0.37, porosity 86%, air permeability 9.3 cm ³ · cm
/ Cm ² · sec · cm H ₂ O to produce a porous ceramic block.

Using these two types of ceramic blocks having a thickness of 65 mm, non-penetrating grooves having a groove width of 9.4 mm and a groove depth of 40 mm are formed on one surface perpendicular to the thickness direction, both having an opening ratio of 31.3. %, They were arranged in parallel at substantially equal intervals with a pitch of 30 mm.

With respect to the obtained two types of ceramic sound absorbing materials, the sound absorption coefficient in a frequency range of 100 to 2000 Hz was measured, and the results are shown in FIG. From this result, the air permeability of the ceramic block of the base material was 1 cm ³ · cm / c.
If m ² · sec · cmH ₂ O or more, it can be seen that an excellent sound absorption coefficient can be obtained by providing a non-through groove. Further, it can be seen that even with the same non-through groove, a ceramic block having a higher air permeability can obtain a better sound absorption coefficient.

Example 6 Using the same porous ceramic block as in Example 1 above, non-penetrating grooves having a groove width of 9.4 mm and a groove depth of 40 mm were formed on one surface perpendicular to the thickness direction thereof so as to be orthogonal to each other. They were arranged at substantially equal intervals with a pitch of 40 mm in both directions so that the ratio became 41.4%.

Regarding the obtained ceramic sound absorbing material, 1
The sound absorption coefficient in the frequency range of 00 to 2000 Hz was measured, and the results are shown in FIG. From this FIG.
It can be seen that in the frequency range of 2000 Hz, an excellent sound absorption coefficient whose maximum value exceeds 0.8 is obtained.

[0040]

According to the present invention, it is made of a porous ceramic block having weather resistance, and is felt uncomfortable by humans.
It is possible to provide a ceramic sound absorbing material which has an excellent sound absorbing coefficient in a frequency range of 00 to 4000 Hz and which has an excellent sound absorbing effect against sounds incident from various directions and angles such as road and railway noises. Moreover, since the ceramic sound-absorbing material of the present invention has a non-penetrating groove on the surface, it is possible to construct a sound-insulating wall having an excellent design property by a combination thereof.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a specific example of a ceramic sound absorbing material of the present invention.

FIG. 2 is a schematic perspective view showing another specific example of the ceramic sound absorbing material of the present invention.

FIG. 3 is a graph showing the sound absorption coefficient of each ceramic sound absorbing material having a non-through groove with a changed groove depth in Example 1.

FIG. 4 is a graph showing the sound absorption coefficient of each ceramic sound absorbing material of Example 2 in which the opening ratio of the non-through groove is changed.

FIG. 5 is a graph showing the sound absorption coefficient of each ceramic sound absorbing material in Example 3 in which the opening ratio of the non-through groove is changed.

FIG. 6 is a graph showing the sound absorption coefficient of each of the ceramic sound-absorbing materials of Example 4 in which the width and the opening ratio of the non-through groove are changed.

FIG. 7 is a graph showing a sound absorption coefficient of each ceramic sound absorbing material using ceramic blocks having different air permeability in Example 5.

FIG. 8 is a graph showing the sound absorption coefficient of the ceramic sound absorbing material of Example 6.

[Explanation of symbols]

 1 Porous ceramic block 2 Non-through groove

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) E04B 1/82-1/86 G10K 11/16

Claims (3)

(57) [Claims] The present invention has a continuous pore having a pore diameter of 0.2 to 2000 μm, a porosity of 60% or more, and a permeability of 1 cm.
^{3 · cm / cm 2 · sec} · cmH consists ₂ O or more porous ceramic blocks, the perpendicular one side in the thickness direction thereof,
A ceramic sound-absorbing material, wherein a non-penetrating groove having a depth of 20 mm or more is provided so as to have an opening ratio of 9% or more. 2. A non-through groove having a groove width of 2 to 50 mm has an aperture ratio of 9
Provided at substantially equal intervals in the range of
The ceramic sound-absorbing material according to claim 1, wherein the maximum value of the sound absorption coefficient in a frequency range of 00Hz is 0.8 or more. 3. The porous ceramic block is obtained by firing a refractory clay and / or a refractory chamotte mixed with a pore-imparting material.
Or the ceramic sound absorbing material according to 2.