JPH0447837B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound insulating plate with improved sound insulating properties.

In recent years, many sound insulation technologies and materials have been researched and developed in order to deal with problems such as residential noise, and building materials are required to have higher performance. That is, from the viewpoint of saving resources, saving energy, and improving safety, insulation, weight reduction, and nonflammability are required, and from the viewpoint of expanding space and improving workability, thinning is required. Therefore, sound insulating materials and sound insulating structures that meet these requirements are also required. However, improving the sound insulation performance of building materials or buildings and the above-mentioned required performance are often in conflict with each other, and it has been difficult to achieve both.

In general, the sound insulation performance of sound insulation materials is roughly determined based on the mass law for sound transmission, and when the areal density is increased, the sound insulation performance is determined by the sound transmission loss (hereinafter referred to as TL). It also improves. Furthermore, in order to increase TL beyond the mass law, it is common to use a double wall or multi-wall structure in which sound insulating materials are arranged in parallel, and to further improve the sound insulating effect by inserting a sound absorbing material or the like inside. However, such a method inevitably results in an increase in weight and thickness. In addition, a particular problem is that even when such a method is used, a significant decrease in TL, that is, a sound insulation defect, often occurs in a specific sound range due to the coincidence effect, resonance transmission in the low range, and the like. A common method to improve this sound insulation deficit is to change the natural frequencies due to the sound insulation material and structure in order to move the frequency range that causes the sound insulation deficit out of the audible range, which is also a conventional method. This tends to cause problems such as an increase in weight and thickness or a decrease in the rigidity of the sound insulating material.
In some cases, the problem can be improved by subjecting the surface material to vibration damping treatment, but generally the cost is high and the effect is insufficient.

In order to achieve high sound insulation as described above,
The biggest challenge is how to achieve sound insulation that exceeds the mass law, and how to prevent deterioration due to sound insulation defects. Currently, double walls or multiple walls are constructed using surface materials with a relatively high surface density (including structural walls such as board materials), and sound absorbing materials such as glass wool and rock wool are inserted inside, making it impossible to address sound insulation defects. In general, with sufficient
Either adopt one with a larger TL, or reduce the sound insulation loss from the beginning within the audible frequency range (e.g. 125Hz~
4000Hz), the design and construction was done without considering the significant increase in thickness and weight.

The present invention realizes a method of suppressing the deterioration of sound insulation performance as much as possible without increasing the thickness or weight. It almost reproduces the sound insulation properties, and in the case of structures using this sound insulation board, it maximizes the increase in TL due to double walls, for example.

The present inventor has investigated the influence of surface density m and bending stiffness B in a plate-like structure, especially along the surface m/B.
We study the TL of a flat plate-like body consisting of a non-uniform region of The inventors have completed the present invention by discovering that the sound can be dispersed or leveled, and that similar dispersion or leveling can be achieved in sound insulating structures such as double walls.

The above phenomenon is caused by the fact that when sound is incident on the entire surface of a board evenly or completely randomly, each part of the non-uniform area of the board exhibits different acoustic behavior, even though it receives uniform air excitation. As a result, the transmitted sound components from each part differ moderately, so
It is believed that the synthesized sound after transmission is adjusted to reduce harmful transmitted sound, that is, sound in a specific frequency range due to sound insulation defects.

The gist of the present invention is that the ratio k of areal density m to bending stiffness B
It is a plate-like structure consisting of a set of bordered areas of a plurality of regions having different = m/B, and the maximum value of k (k max.) and the minimum value of k (k min.) of the plurality of regions.
the ratio of 1.2 or more, and the sum of the areas of regions having a larger value (k + ) and smaller value ( ^{k - )} than the weighted average value ( ) of k in the total area of the plate-like area. each has at least 25% of the total area of the plate, and the average diameter of the maximum circle included in each region having the k ⁺ value is (π/850)×(B/m) ^1/2 The structure of the sound insulation board is as described above.

That is, in the present invention, the m/B of each region is varied so that each region of the board exhibits different acoustic behavior, and the sound insulation defect frequency of each region is adjusted to an appropriate level in order to suppress the level of transmitted sound due to the sound insulation defect. By separating the parts and reducing the transmitted energy to a level corresponding to the area of each part, sound insulation defects are dispersed and leveled, and the overall sound insulation level, for example, the sound insulation grade D-value, is improved.

In the present invention, k=m/ of each region
Maximum value (k max.) and minimum value (k min.) of B
It is necessary that the ratio is 1.2 or more. In other words, the coincidence limit frequency c = (c ² /2π) ×
(m/B) ^1/2 (c is the speed of sound, m is the areal density of the area, and B is the bending rigidity of the area) is separated by 10% or more. Therefore, when k = m/B, k
It is necessary that the ratio between max. and k min. be 1.2 or more. If this ratio is less than 1.2, the dispersion and leveling effect in the coincidence limit frequency region will be poor, so it is preferably 1.5 or more, and more preferably 2.0 or more. In addition, m, B in the above area
Each value is calculated assuming that the part is an ideal model and is part of an infinite flat plate.

The invention relies on the composite effect of the different acoustic behavior of each of the bounded heterogeneous regions, for which k
The effect is poor unless the region with a larger value (k ⁺ ) and the region with a smaller value (k ^- ) each occupy a certain area or more of the plate-like body, and the experimental results show that k ⁺ and k ^- It is a coincidence that the areas with k ⁺ and ^k- that are 10% or more smaller each occupy 25% or more of the total area of the plate-like body, respectively. This is preferable in order to obtain a dispersion effect in the critical frequency region.

And the acoustic behavior of the region with k ⁺ and k ^- is
It is affected not only by area but also by its shape. Particularly in the case of isotropic materials, even if the area is large, a frame-like or comb-like shape, for example, will not be effective, so it is preferable to have a circular or square shape. In this way, it is necessary to specify the shape and set the area to a value greater than a certain value. This required minimum area will be referred to as the critical area. When this critical area is taken into account the shape to be specified,
It has been found that it is best to represent the largest circle included in the shape, that is, the area of the circle that touches the contour formed by a straight line or curved line at two or more points, and the area of the circle that is the largest of the circles included in the above area. .

Assuming that the diameter of the maximum circle included in this way is dm, as a result of experimenting with various shapes, the above-mentioned
The dm in the region with k ⁺ or k ^- is related to the wavelength of the bending wave at the coincidence limit frequency c = (c ² / 2π) × (m/B) ^1/2 , and dm ≥ (π / 850) × ( B/
m) It was shown that it is necessary to be ^1/2 .
Below this value, the effect of leveling and dispersing the sound insulation defects is poor, and the value is preferably (π/200)×(B/m) ^1/2 or more. Therefore, the arithmetic mean value of each maximum circle of each region with k ⁺ or k ^- is (π/850) ×
(B/m) The effect is small unless it is ^1/2 or more.

Note that the shape of each area may be such that acoustically meaningless thin notches or areas that are parallel to each other with a narrow interval are considered to be the same area, ignoring the notch or interval.

As a method for obtaining a board consisting of regions with different m/B, when the cross-sectional shape is constant, the areal density and bending rigidity may be changed independently, or both may be changed as appropriate. If desired, the same material may be used with different thicknesses, or another plate may be laminated on the plate surface, and in any of the above cases, the non-uniform region may be divided into a plurality of locations. Note that when partially laminating, if a material with low rigidity and high areal density is used, such as a soft sound insulating sheet, only the areal density of that part will increase, resulting in k
can be effectively improved, and the dispersion effect becomes extremely high. Also, due to the lamination of this soft material,
The separation of c occurs on the treble side of c, which is particularly advantageous in terms of sound insulation from the relationship of the radiation coefficient, and was found to be the best measure to improve sound insulation deficiencies. It has been found that when partially laminated to form regions with different m/B, the sound transmission loss in almost all frequency ranges except c becomes the average value of the values of each region according to the mass law. It was. Therefore, it is presumed from this that the mass law based on areal density is applied in the above method of obtaining regions with different m/B except for c. Note that the sound insulation board of the present invention can be used even if it is incorporated into any structure, for example, a structure whose main purpose is not sound insulation. Further, when joining a beam or the like, it is better to overlap the joint part of the beam or the like with the boundary between regions having different k. This is because, for example, when a material with high rigidity and density, such as a beam, is joined to a plate-shaped sound insulating surface, the acoustic behavior within the nearby plates tends to average out, and the dispersion effect is no longer exhibited. This is because while it is necessary to eliminate this adverse effect, if it is used over the boundary, separation of the acoustic behavior of the two divided regions may be promoted. Therefore, the soft material made heterogeneous according to the present invention has a very high effect. Furthermore, soft materials
In addition to the above-mentioned special notes, the method of the present invention becomes a material that can be used most effectively due to the improvement in TL based on the mass law due to an increase in areal density. Therefore,
This is extremely important as a new way to use soft sound insulation sheets. Furthermore, it is clear that the present invention is applicable not only to flat plates but also to curved plates.

As described above, the sound insulation board according to the present invention has the effect of synthesizing transmitted sound from regions with different acoustic behaviors.
The drop in TL at c is leveled or dispersed, and in almost all frequency ranges other than c, a contribution according to the mass law due to the increase in areal density is obtained, and the TL is improved. As a result, with a relatively small increase in the thickness and weight of the sound insulation board, it is possible to maintain lightness and ease of handling that could not be achieved in the past, and to greatly improve excellent sound insulation performance, such as the sound insulation grade D-value. I can do it.

Hereinafter, the sound insulating plate according to the present invention will be described in more detail with reference to Examples.

Example 1 Heavy-duty silica asbestos board - Soft sound insulation sheet - Heavy-duty face material formed from a heavy silica asbestos board (area density m
=14.7Kg/ ^m2 , bending rigidity B=910N・m, k=
0.0162) 90×90cm board and lightweight Keical asbestos board (m
= 4.5Kg/m ² , B = 79N・m, k′ = 0.0570) 90×
The 90 cm boards were joined together into a single board so that one side of each board met. k′/k=3.53. The area of each is 1/2 of the previous one, the diameter of the inner circle is 90cm, and (π/
850)×(B/m) ^1/2 = larger than 6.5cm. About this sound insulation board Each 1/3 octave center frequency (Hz)
The TL was measured. Measurement is JIS-A-1416
Based on the sound transmission loss measurement method in reverberant walls. All of the following examples were also measured using this method. The results are shown by the solid line in FIG. For comparison, the heavy-duty surface material with the same dimensions (dashed line in the same figure),
The measurement results for lightweight calcic asbestos board (dotted line in the same figure) are listed. c (2k~3.5kHz) as shown in Figure 1
In other frequency ranges, the TL is between the heavy facing material and the lightweight siliceous asbestos board, and exceeds that of the heavy facing material near c.

Example 2 Water resistant Class 1 3ply plywood thickness 3.0 mm (m = 1.65, B
= 15, m/B = 0.110), 90 x 90 cm, and the same plywood, 5.5 mm thick, 90 x 90 cm, and one side of each plywood was brought together to form a single sound insulating board. 5.5mm plywood m=3.03, B=92, m/B=
It was 0.0329. The results are shown by the solid line in FIG. For comparison, 3mm plywood of the same size (dotted line in the same figure), 5.5mm
The results for plywood (dashed line in the same figure) are listed. In the example c
It can be seen that the drop in TL has been significantly improved in the vicinity.

Example 3 A veneer of lightweight silica asbestos board 90 x 180 cm sound insulating board (dotted line in Figure 3), when this board is laminated with a 90 x 30 cm board of the same quality and thickness to the left of the center line of the board (dashed line in Figure 3, laminated (The area is 16.7% of the total) and the case where a 90×90 cm plate of the same quality and thickness is further laminated on the unlaminated surface on the right side (Example, solid line in Figure 3). As shown in Figure 3, when the laminated area is insufficient, there is almost no difference from the case of veneer, but in the example, it is around c (around 5k).
TL has been improved by more than 5dB.

Examples 4 and 5 In the case of a 90 x 180 cm single heavy silica asbestos board (dotted line in Figure 4), when a 90 x 60 cm board of the same quality and thickness is laminated from the left end (Example 4, broken line in Figure 4) and Furthermore, the measurement results are shown when a lightweight calcical asbestos board of 90 x 60 cm was laminated on the right side in contact with the heavy silica asbestos board (Example 5, solid line in Figure 4). As shown by the curves of Example 5 as well as Example 4, even if the laminated layers are not of the same quality and thickness, an improvement of more than 5 dB is achieved even in the c range (4 kHz to 5 kHz) due to the increase in the laminated surface. I understand.

Examples 6 and 7 Lightweight surface material (m
= 11.1, B = 607) If only 90 x 180 cm (dotted line in Figure 5) is used, lightweight silica asbestos board (m = 4.5, B
=79) When 90 x 60cm plates are stacked from the left end (Example 6, broken line in Figure 5), the same plate
When 90 x 60 cm pieces were additionally laminated (Example 7,
The measurement results shown in Fig. 5 (solid line) are shown. As shown in Figure 5, due to the increase in lamination area, the TL in region c is
The improvement will also improve.

Example 8 Heavy-weight surface material 90× made by laminating the entire surface of heavy-duty silica asbestos board, soft sound insulation sheet, and heavy-duty silico-asbestos board
Figure 6 shows the measurement results for the case of only a 180 cm plate (dotted line in Figure 6) and the case where a 90 x 90 cm panel of the same quality and thickness was laminated on the left half (Example 8, solid line in Figure 6).
It can be seen that the TL in the c region is similarly improved with the heavy facing material.

Example 9 In the present invention, it was determined whether or not there was a difference in TL depending on the lamination method when top layers were laminated. Simply place it (dotted line in Figure 7) and fix it by nailing (Figure 7)
(Dotted line in the figure) and adhesion using double-sided adhesive tape (No. 7)
As shown in the results (solid line in the figure), all plots are plotted on almost the same curve, and the T.
No difference was observed between L.

[Brief explanation of the drawing]

1 to 7 are drawings showing the relationship between center frequency (Hz) and sound transmission loss (TL, dB) for the above-described embodiments and comparative examples of the present invention.

Claims (1)

[Claims] 1 A plate-like structure consisting of a set of adjacent boundaries of multiple regions having different ratios k=m/B of surface density m and bending stiffness B, where the maximum value of k of the multiple regions (k
The ratio of the minimum value of k (k min.) to the minimum value of k (k min.) is 1.2 or more, and a region having a value (k ⁺ ) larger than the weighted average value () of k in the total area of the plate shape and a smaller value The sum of the areas of the regions having (k ^- ) each has at least 25% of the total area of the plate, and the average diameter of the largest circle included in each region having the k ⁺ value is ( π/850)×
(B/m) ^1/2 or more.