JPH01221799A - Sound absorbing panel product and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a substitutive sound absorbing panel product by performing formation from the compressed and connected small pieces of a lignocellulose material. CONSTITUTION: This product is composed of the compressed and connected small pieces of the lignocellulose material, the small pieces are in the same size and shape, at least many small pieces are oriented on the main surface of the panel product so as to extend many sound absorbing clearances between the adjacent small pieces at least from one side of the panel to the inside of the panel and compression to a certain density is performed. That is, a low density area 1 forms the main part of the product and a high density area 2 is passed through the panel product in a vertical direction from one main surface of the panel product to the other main surface. The low density area 1 is formed from compressed wood thin pieces and the surfaces of many thin pieces are extended vertically to the main surfaces on both sides of the panel and parallelly to the high density area, that is a rib 2, and the high density rib 2 is constituted of smaller wood fibers. Thus, this sound absorbing panel product composed of the small pieces such as the wood thin pieces or the like is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to acoustic panel products and methods of manufacturing acoustic panel products.

Sound absorbing or sound insulating products or materials are used in offices, factories, and many other uses to reduce noise.

Room noise, such as office noise, makes people tired and irritable, reducing the amount of time they have to concentrate. If adjacent offices are not soundproofed, secret conversations will not be possible. High noise levels in factories require measures to prevent hearing damage to workers.

Various forms of sound absorbing products and materials are known, such as materials based on mineral fibers, glass fibers and wood wool. The present invention provides an improved or at least alternative acoustical panel product and method of making the same formed from modified lignocellulosic materials, such as small pieces of wood flakes.

The invention comprises, in a first aspect, strips of compression bonded or bunocellulosic material, the strips being of the same size and shape, such that a number of sound-absorbing voids between adjacent strips form at least one side of the panel. orienting at least a plurality of strips on a major side of the panel product so as to extend into the panel from the side of the panel;
It consists of an acoustic panel product that is compressed to a certain density.

In a second aspect, the invention provides, under heat and/or pressure,
A method of manufacturing an acoustical panel product comprising forming a panel of small pieces of lignocellulosic material compressed with a binder, the pieces being of the same size and shape and having a plurality of sound-absorbing voids between adjacent pieces at least At least a plurality of strips are oriented on a major surface of the panel product and compressed to a density so as to extend into the panel from one side of the panel.

Most preferably, the panel product of the present invention is constructed from wood flakes or flakes in which one size on one side of the panel product is larger than the other size on the same side. There are a number of voids between adjacent pieces. The foils are compressed to a relatively low density so as to be oriented on the major sides of the panel product so that, in use, the voids are open on at least one major side exposed for sound absorption.

The panel product thus formed has effective sound absorbing properties as described below.

Many known effective sound-absorbing materials have little physical strength and therefore must be attached to an existing wall or ceiling frame specifically formed to support the sound-absorbing material. On the other hand, for example, bulkhead screens in offices that are said to be for sound absorption either do not have very effective sound absorption properties or require a separate rigid frame to support the soft filler material, such as glass fiber, which forms the bulkhead. I need.

The panel product of the present invention requires a wall frame so that it has structural strength at least to the extent that the panel product can stand on its own, and that the panel product itself can withstand other loads, such as as a wall or ceiling member, especially as an internal bulkhead. It is formed to have sufficient structural strength to be used without any need for protection. The panel product so formed consists of longitudinally spaced compacted pieces of relatively low density with a large number of voids so that the dense areas help provide structural strength to the panel product. It is preferable to consist of high-density regions. These dense regions are likewise composed of compacted pieces of lignocellulosic material, such as smaller wood fibers.

Panel products of the present invention having longitudinally extending dense areas also have improved sound transmission prevention properties. Another physical property that affects soundproofing is the strength of the bulkhead. Sound impinges on the septum over a range of subject incidence angles, and the wavelength of the incident sound coincides with the characteristic flexural vibrations of the septum, whereupon the sound is easily transmitted through the septum. That is, at certain frequencies there is a soundproofing loss for transmitted sound. This effect is known as the "congruency effect." The result is that instead of the sound insulation value (STC) of the sound-absorbing bulkhead gradually increasing with frequency, there is a decline in the graph of transmission loss versus frequency, after which the transmission loss increases again with frequency.

The most important frequency range for soundproofing is 100-400
0H2, fact, for example conversation is below 100Hz, 5KH
It does not have a frequency higher than z.

Although soundproofing above 4 KHz is usually adequate for the use of conventional materials, it is generally in the 100 Hz to 1000 Hz frequency range that sound absorbing structures generally fall short of the desired results. The panel product of the present invention is characterized by panel bending (f 1
(exural) designed to reduce sound transmission resulting from vibrations.

Modern homes and offices with numerous machines such as dishwashers and typewriters require walls with high sound absorption coefficients and high sound absorption and transmission coefficients, as well as load-bearing performance. Must meet normal building requirements.

In at least a preferred form, the panel products of the present invention are designed to have good sound absorption and low sound transmission properties, as well as sufficient structural strength to serve as a panel wall member without the need for a separate structural frame. is formed.

The acoustical panel product of the present invention is formed from compacted or glocellulose material pieces. In almost all applications the chips consist of wood chips, but other forms of lignocellulosic material can be used, such as wood bark chips. The lignocellulose pieces are compressed with a suitable binder to form a composite panel product. The technique of forming modified wood products by compressing small pieces of wood under heat and pressure with a binder such as a thermoset resin into the form of a rigid panel product is well known and will not be described in detail here.

In the present invention, the pieces are compacted to a relatively low density while forming the described panel product. Higher densities provide lower sound transmission prevention and absorption properties, but for any application the density should be sufficient to achieve the desired structural strength. The pieces are preferably compressed to a density in the range of 350-600 kg/m3, with a density of 480 kg/m3 providing a final product with a good balance of sound absorption, low sound transmission and structural strength.

Although the wood chips are formed as flakes or flakes, other shapes of chips can be used, such as square, hexagonal, round, or other various shapes. Most preferred are flakes or flakes in which one size in a major face of the panel product is larger than the other size of the flakes in that face, although not conventionally referred to as flakes.

In the case of flakes, the thickness, ie the size of the flakes perpendicular to the plane of the flakes, is in the range 0.3-4 nm. Below 0.3 mm, the flakes are compressed too tightly and the gaps between adjacent pieces are less than desired.

In general, the longer the flake is, the better; its width is not critical; however, the length of the flake is preferably in the range of 20 to 100 mm, and the width is preferably in the range of 2 to 20 IIffl.

It was found that a thin piece with a thickness of 0.6a+i to 0.7a+Ill, a length of 62cm, a width of 3 to 60mm, and a center width of 1511Ill gives a good finish.

The wood chips or flakes are compressed with a suitable binder, such as a urea formaldehyde binder, to orient the chips so that there are a number of voids between adjacent chips that are open to at least one major side of the final panel product. to form panel products with relatively low density. The size of the voids is determined by the size and morphology of the wood chips, such as flakes, used and the density with which the chips are compressed. When flakes are used as the wood chips, they are oriented such that at least a plurality of the faces of the flakes extend transversely to the main face of the panel product.

Most preferably, the panel product also includes spaced apart regions of relatively higher density extending through the panel between regions of lower density compressed flakes that also have voids.

These high density regions can be formed from modified lignocellulosic materials such as highly compacted wood fibers, such as those of medium density fibreboard. High-density areas allow the panel product to be held vertically so that the resulting panel product has both sound absorption and low sound transmission properties, as well as good structural strength, allowing the panel to serve as a free-standing wall or ceiling member. Preferably, it extends in the direction and helps provide structural strength to the panel.

A preferred form of the panel product of the present invention comprising high density ribs is shown in FIG. FIG. 1 is a view of one main plane. The low density areas are shown in (1) and the high density areas or ribs are shown in (2). Low density regions form the main part of the product.

High density regions run lengthwise through the panel product from one major side to the other major side of the panel product.

In the panel shown, the low-density region (1) is formed from compressed water flakes, the faces of the many flakes being perpendicular to the main planes on either side of the panel, and the high-density regions or ribs (
2) Extends parallel to. The dense ribs (2) are composed of smaller wood fibers. The high-density region (1) also includes a region of densification of flakes or other particles or a large amount of resin, forming a low-density region (2), instead of another region of wood fibers or other particles. The densities thus formed may be approximately equal to the discrete fibreboard densities shown.

The corner marked (A) of the first panel is shown in more detail in FIG. With respect to FIG. 2, the individual flakes in the low density region (1) extend approximately in the direction of the arrow (I3). Figure 2 shows small holes arranged in an integral pattern extending across the face of the panel as Helmholtz resonators to increase the sound absorption properties of the panel. The frequency at which the Helmholtz resonator is most effective varies depending on the hole size, depth, and spacing.

The thickness between the major surfaces on which the panel product is formed is determined by the application. Generally, the thicker the product, the more difficult it is to pass through the panel. If structural strength is required for the panel product, determine the thickness required for the application.

In particular, the panels are 20 to 2001111 mm thick. For example, a wall panel of 100III11 for a full-height freestanding bulkhead between offices (floor to ceiling) and a thickness of 50rA for a larger ceiling panel.
The thickness of I11 is appropriate. Lightweight, smaller ceiling panels intended to replace existing plaster or similar panels, for example in suspended ceiling tile systems, are formed to a thickness of 20+ qm.

The panel product of the present invention is covered with a suitable textile material either during manufacturing, where the panel is manufactured as a finished bulkhead or ceiling panel, or after construction of the wall in the field. Painting the panel or covering the panel with wallpaper or the like should be avoided as this reduces the sound absorption properties of the panel.

A wall covered with a sound absorbing plate is formed using the panels of the present invention by sandwiching a steel plate between the panels on both sides.

The panel products of the present invention are formed by the method of the present invention using the conventional heat and pressure modified wood product techniques described above, by orienting the pieces or flakes from which the product is formed in the direction in which the present invention is achieved. .

A preferred form of the invention comprising low-density regions with voids and high-density ribs includes first forming an intermediate panel by compressing a lower layer of wood fibers, an intermediate layer of flakes, and an upper layer of wood fibers. It is formed as appropriate. Techniques for manufacturing such panels in which the face of the flake extends onto the face of the intermediate panel are known, and such panels used as intermediate panels in the manufacture of the panel products of the present invention are manufactured by New Sealant No.
It is a commercially available triple veneer panel manufactured and ordered from rthern Pu1p Ltd (Northern Bulbs Limited) under the trademark rTUFTIMJ.

Cut these middle panels lengthwise into strips;
The strips are then rotated 90@ to bring the fiberboard sides of adjacent strips into contact and join them back to back to form the panel product of the present invention.

The density at which the top and bottom fiberboard layers and the central lamina core of the intermediate panel are formed determines the density of the low density and high density areas in the finished panel product of the present invention, and the size at which the strips are cut determines the thickness of the finished panel product. Determine.

In addition, the above-mentioned multiple intermediate panels are manufactured by bonding the fiberboard side of each panel and the adjacent panel side back to back to form a laminate, and then cutting the laminate, for example, with a hand saw, in a direction transverse to the surface of the intermediate panel. The panel product of the present invention is formed by cutting into pieces.

The height at which the laminate is formed determines the width of the panel product of the present invention.

Examples of the present invention will be described below.

Example 1 An intermediate panel was made by press-tubing a core layer made of wood flakes and upper and lower layers made of wood fibers. The wood flakes have a thickness of 06
In the range of 6■ to 0.7■, the length of the central part is 62n+a+
, the width varied, ranging from 31 to 6011 III, and the width at the center was about 15a+n+. The middle panel was compressed to a density of 480 kg/m3 in the center of the lamina. The intermediate panel thus produced has a length of 4 m.
The width was 2.5 m and the thickness was 0.6111+n. The middle panel was then cut lengthwise into strips of 50aa+ width (50ml width was measured in the plane of the middle panel). Rotate each strip 90 degrees
The fiberboard sides of adjacent strips were then bonded together with a urea formaldehyde cold curing adhesive and cured for 24 hours. The panel product thus formed had a thickness of 50 mo+.

Example 2 A panel product of the present invention was formed as described in Example 1 with the following exceptions. The intermediate panel of the present invention was cut into strips having a panel plane width of 100 ID11, resulting in a panel product of the present invention having a thickness of 10 C1v.

Example 3 A product panel was formed as described in Example 1. After this formation, 9
000 holes/m2 were drilled. Each type has a diameter of 5■
The depth was 25av.

FIG. 3 shows the sound absorption coefficients of three product panels in Examples to Example 3 versus frequency. For production panels of 50 mm thickness and 100 IllI11 thickness without a Helmholtz resonator, the sound absorption coefficient increases monotonically from 0.3 at 125 Hz to 0.7 at 5 KHz. For the 50 raIll thick product of Example 3 with Helmholtz resonator, 100% sound absorption is achieved over the important frequency range.

This frequency range can be adjusted by changing the depth and diameter of the holes and the spacing of the Helmholtz resonators.

The fourth figure represents the sound attenuation index for the frequency of the three plates.
The figure shows the sound transmission characteristics of the three plates described in Examples to Example 3.

The transmittance of the 50 mm thick plate of Example 1 and the 100 ma+ thick plate of Example 2 is 27 dB and 39 dB, respectively, and the (sound reduction index) lower limit matching frequency is 250 Hz and 200 Hz, respectively.
It is Hz.

(Sound Reduction Index) The lower limit matching frequency depends on the elastic modulus, density, and thickness of the product panel. By varying the board quality, thickness, and number of fiberboard ribs per meter, the (sound attenuation index) lower matching frequency of the 100 ■ plank can be reduced to 100 Hz or less, which is the sound transmission coefficient. resulting in a significant increase in One of the advantages of the panel product of the present invention is that it can be designed to have optimal sound transmission properties for any application.

Similarly, if good sound absorption is of paramount importance, the product panel should be
Can be designed for maximum sound absorption.

Table 1 below compares the structural properties of the panel product of the present invention with high density fiberboard ribs to conventional vertical main wall assembly studs erected at 600,111 spacing. The required panel thicknesses are shown to provide comparable stiffness and strength to three different sizes of studs.

Other than its thickness dimension, the panel product was made as described in the examples above.

TABLE 1 The foregoing describes the invention, including preferred forms thereof. Modifications and variations that are obvious to those skilled in the art are intended to be within the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is an enlarged detailed perspective view of part A in FIG. It is. FIG. 4 is a graph of sound transmission reduction index versus frequency for various forms of panel products of the present invention. (1) Low-density region, (2) High-density region (rib) Patent applicant: Terrence Douglas Lomax
Rudolf Nidward Booker Model Salesman IY Seimitsu (Method 0 March 1, 1999 1) Indication of the case 1985 special y "Application No. 253610 2, Name of the invention Sound-absorbing panel product and its manufacturing method 3 Relationship with the 4-party case for amendment Name of patent applicant Terrence Douglas, 1 other person and 4 agents 5 Date of amendment order January 6, 1985

Claims (1)

Claims: 1. consisting of small pieces of lignocellulosic material compressively bonded such that a number of sound-absorbing voids between adjacent pieces extend into the panel from at least one major side;
An acoustical panel product sized and shaped such that the chips are compressed to a density such that at least a majority of the chips are oriented on a major surface of the panel product. 2. The sound-absorbing panel product according to claim 1, wherein the region of the panel product consisting of a large number of sound-absorbing voids is divided by high-density regions extending vertically through the panel at regular intervals. 3. The acoustical panel product of claim 2, wherein the high-density region also comprises compressed lignocellulosic material. 4. The acoustical panel product of claim 3, wherein the high-density regions are comprised of compressed fibers, and the average size of the fibers is smaller than the average size of the pieces constituting the low-density regions between the high-density regions. 5. The sound absorbing panel product according to any one of claims 1 to 4, wherein the small pieces on the same side of the panel product have different sizes. 6. The acoustical panel product of claim 5, wherein the pieces are generally in the form of flakes. 7. The sound absorbing panel product according to claim 5 or 6, wherein the small pieces or thin pieces are oriented such that a majority of the small pieces or thin pieces extend substantially parallel to the longitudinal direction of the high-density region. 8. The sound absorbing panel product according to any one of claims 1 to 7, wherein the small pieces are compressed to a density range of 350 to 600 kg/m^3. 9. The small piece has a length range of 2 to 10 mm and a thickness range of 0.3 to 10 mm.
9. The sound absorbing panel product according to claim 1, having a width of 4 mm and a width range of 2 to 20 mm. 10. The acoustic panel product according to any one of claims 1 to 9, wherein the lignocellulose material is wood. 11. Claims 1 to 1 comprising a pattern of small sound-attenuating voids extending at regular intervals into the panel from the main surface.
Sound absorbing panel products listed in any of items up to 0. 12. An acoustical panel product according to any of claims 2 to 11, wherein the panel strength is sufficient to allow it to be used as an internal partition wall without a separate structural framework. 13. The wall or wall panel has a thickness range of 50-200mm
The sound absorbing panel product according to any one of claims 1 to 12. 14. The ceiling or ceiling panel has a thickness range of 20-50m.
The sound absorbing panel product according to any one of claims 1 to 13, which is m. 15. The sound absorbing panel product according to claim 13 or 14, wherein the panel surface exposed during use is covered with a fiber material. 16, forming a panel consisting of small pieces of lignocellulosic material compacted with a binder under heat and/or pressure, such that a number of sound-absorbing voids between adjacent pieces are formed in the panel from at least one major side; A method of manufacturing an acoustical panel product, the size and shape of which is such that the particles are compressed to a density such that at least a majority of the particles are oriented on a major surface of the panel product. 17. The method of manufacturing an acoustic panel product according to claim 16, wherein the panel product is formed with high-density regions extending vertically at regular intervals throughout the panel. 18. First, form a nearly rectangular strip consisting of a low-density core made of compressed pieces and high-density layers on both sides of the core, and then form a large number of strips with the high-density layers of adjacent strips back to back. 17. The acoustical panel of claim 16, wherein the adhesive forms a panel product, whereby the core of the strip becomes a low density region of the panel product and the adjacent dense layer of the strip forms a dense layer of the panel product. How the product is manufactured. 19. The method of claim 18, wherein an intermediate panel is first formed comprising a low density core and a high density layer on each major side, and then the major sides of the intermediate panel are cut transversely to form the strips. manufacturing method for acoustic panel products. 20. Forming a number of intermediate panels consisting of a low-density core made of compressed pieces and a high-density layer on each major side, and bonding several high-density layers of adjacent intermediate panels by stacking them back to back. 18. The method of manufacturing an acoustical panel product as claimed in claim 17, comprising the steps of: cutting transversely across a major surface of the stack to form a plurality of panel products. 21. The density of the low density region is 350 to 600 kg/m^
21. The method for producing an acoustic panel product according to any one of claims 17 to 20, which is within the range of 3. 22. The method for producing an acoustic panel product according to any one of claims 17 to 21, wherein the small pieces are made of wood flakes and the high-density regions are made of wood fibers. 23. Small piece has a length range of 2 to 10 mm and a thickness range of 0.3 to
4 mm, and the width range is 2 to 20 mm. Claims 14 to 22
A manufacturing method for the sound absorbing panel product described in any of the above.