DE2752343A1 - SOUND INSULATION ELEMENT - Google Patents

Description

800U MUiICIIuM t

Folder: 24352 - Dr.K / vS / Hö ICI CASE Du 29181

IMPERIAL CHEMICAL INDUSTRIES LTD. London - Great Britain

'Soundproofing element "

PRIORITY: November 23, 1976 - 48760/76

Oct. 21, 1977 - Great Britain

The invention relates to sound insulation components.

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As is known, porous materials in which the pores completely pass through the entire basic structure, for example open-cell polyurethane foams, absorb sound energy. Other sound absorbing materials are Mineral fibers commonly used as tiles.

The sound energy is absorbed in all of these materials because the air - as the carrier of the sound wave - is in the pores of the material is subject to frictional effects. Part of the energy absorption can also be through mechanical Vibrations (resonance). For example, cell wall vibrations can occur in urethane foams.

A material is also known which has no resonance and at least 50% of the incident in the range of 500 to 4000 Hz Can absorb sound energy. This material has at least 90% sand grit with a particle size of 0.15 to 0.50 mm and 2-8% by weight, preferably 5% by weight, of a curable resin. This composition of matter is called wall covering used, either in the form of tiles, tiles or paneling or as a covering of the immediate Is applied or cleaned on the spot.

Components that are made entirely of a sound-absorbing material and are able to take on the function of load-bearing parts in buildings are not yet known.

The term "component" should bricks or plates are understood, which are suitable for producing such screens, walls, floors and ceilings that are built or are only in place as complete units produced.

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The invention now creates a sound-absorbing component which can be used as a load-bearing part and has a thickness of at least 50 mm, which is a rigid, open-cell structure made of a bonded material with a (still defined) porosity between 0.15 and 0.7 and a (to be defined) air flow resistance has between 10 and 180 cgs units.

The invention also relates to a method of manufacture such components as well as on shields, walls, floors and ceilings built from these components.

Suitable starting materials for the component according to the invention sand, flint and granite. For this purpose, a not exceeding 2 mm, preferably between 0.5 and 2.0 mm / Particle size proved advantageous.

The starting material can be bound with various inorganic or organic binders. The nature of the binder is insignificant with regard to the sound absorption properties of the structure. It is only important insofar as the structure must have sufficient structural strength for the intended use. Suitable binders include curable resins such as polyurethanes, epoxy resins and unsaturated polyester resins, sodium silicate and "Winnofos" phosphate binder available from ICI Ltd., Mond Division, "Winnofos" being a trademark.

Flint and sand are used as starting materials and these bound with polyurethane or epoxy resin, a printing

2
Reach strength up to 140 kp / cm (2000 psi).

"Porosity" is to be understood as the ratio of the free space in the structure to the total volume of the structure.

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In the case of an open-cell structure according to the invention, the Porosity can easily be determined, for example by the liquid absorption capacity.

The term "airflow resistance" provides a measure of the obstacle which a structure the thickness of one unit poses to an air flow to be blown through this structure opposed. The air flow resistance R is defined by the following equation:

1. R = p / d / u cgs units,

where ρ = the pressure difference in dyn / cm, which is at a Structure of thickness d cm is measured when air is blown through the structure at a flow rate of u cm / sec will. Apparatus suitable for measuring these parameters using known techniques is known; by the way, a such device can also be easily built.

The porosity of the structure affects its structural strength. In general, the greater the porosity, the weaker the structure. A structure with a value above 0.7 Porosity is not suitable as a component that can take on load-bearing functions. However, the porosity is less than 0.15, then the structure does not have good sound absorption.

The components according to the invention show good sound absorption for all sound waves with frequencies within the audible range. For a component with a given thickness and porosity However, there is an optimal value for the air flow resistance, which is a maximum sound absorption for any frequencies ensures. This optbial value can be determined empirically will.

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The values for the air flow resistance and the porosity depend on the particle size and shape of the starting material as well as the starting material / binder ratio; this results from the following table:

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material
art Sieve size % return
held
sand » Fabric / bandage
medium-ver
ratio Airflow
mismatching
stand (cgs-
Units) porosity "Garside"
21 sand Sieve
size
(mm) 0.8
34.6
47.5
13.6
3.1
0.3 (18 mesh)
0.852 mn 30: 1 154 0.2 Il 1.0
0.71
0.5
0.355
0.25
0.15
0.106 (30 mesh)
0.5 mm 60: 1 154 0.3 Flint 97% held back
ten at
(20 mesh)
0.82 mm 30: 1 42 0.45 M. Il 30: 1 72 0.45 sand 20: 1 14th 0.3 Il 60: 1 14th 0.4

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In order to obtain a structure with an air resistance between Any two values given in the table must be either the particle size of the substance used or the one used Mixtures of substances are changed. The porosity can can be varied by changing the substance / binder ratio. The fabric / binder ratio is usually between 20: 1 and 60: 1.

The substance / binder ratio of the mixture used can i.e. on the intended use, i.e. on the sound frequency to be absorbed and the load that the component carries should be suspended. A component whose thickness does not exceed 50 mm absorbs in the event of air resistance the structure of less than 10 units in the cgs system, the sound in the audible area is insufficient. The same goes for one Component with an air resistance of more than 180 units in cgs system, regardless of its thickness.

The component can be made by using a colored base material be given a more appealing appearance. This is achieved in that the starting material is preceded with a colored resin its further processing is overdone. Raw materials with different colors can also be used.

Sound insulation and sound absorption are different properties of a given material. A good sound absorber is not necessary as a good sound isolator because of the properties the absorption and insulation depend on different parameters.

At a given frequency, the sound insulation of a component generally increases with its mass increase; However, in addition, is also the material of significance used for the device.

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The speed of sound in air is the same for all frequencies; however, this does not apply to the speed of flexural waves in a component, which increases with increasing frequency. This is because flexural waves are a completely different one Behave than the air-transmitted compression waves. Bending waves can because of the low molecular forces of attraction of air molecules do not occur in air. In solids, on the other hand, they can pass on or transmit sound very well.

Since the speed of the bending waves changes with the frequency for a given material, there is a certain frequency at which the speed of the bending waves is equal to the speed of the sound waves in air. This frequency is known as the "critical frequency" and is usually in the upper audible range. Taking into account that the frequency of the two different wave types is the same in both materials, namely in air and in solid bodies, it follows from the equality of the speeds of the waves mentioned that the wavelength in air is exactly the same as the wavelength of the flexural wave in the component. This exact match of the wavelengths is known as the "coincidence effect" and means that the sound energy from the air is better transmitted into the component, and accordingly the component has a lower Isolationswir effect . The lower the flexural strength (dynamic module) of an element, the higher its critical frequency.

The formation of a component to a good sound insulator therefore depends not only on the fact that the mass of the component is sufficiently large, but also on the fact that its dynamic module is kept as small as possible so that the critical frequency is as high as possible. (A reduction in the dynamic modulus also means that the frequency at which the ("spring mass or jump

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mass ") resonance is also depressed. However, this effect is only significant if there is an isolation of frequencies below 100 Hz are required).

Unfortunately, a small dynamic module is not compatible with good structural properties. However, it is possible the coincidence effect through internal damping, i.e. through use of a material with a high damping factor, sometimes referred to as loss factor.

The applicant has now found that a component with good sound insulation and sound absorption is obtained if the Thickness of the inventive component increased to at least 100 mm and a non-vitreous resin binder used.

According to a further embodiment of the invention, a structural element that can be used as a load-bearing part is obtained

in the frequency range from 100 Hz to 10 Hz both as a sound absorber as well as a sound insulator, has a thickness of at least 100 mm and a rigid, open-cell structure of a bonded fabric with a porosity in the range from 0.2 to 0.7 and one in the range from 40 to 180 Units in the cgs system lying air flow resistance (as defined above), the fabric with a resin binder is bound, which does not behave like glass in the sound frequency range to which the wall is to be exposed.

The component is also characterized by a density in the range between 1.5 to 2.0 g / cm, one in the range between 0.02 and 0.10 loss factor and an im

6 8
Range between 10 to 10 units in the cgs system «(still defined) dynamic module.

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The loss factor is a well-known expression. In the case of a resonance peak, the loss factor Π can be derived from the following Equation to be calculated:

² I. = ^Df n ^{/ f} n '

where Df is the bandwidth at the half-value points (3dB points) and f is the resonance frequency. The index η gives the order the resonance or the mode number.

The "dynamic module" is also a well-known term. It can be determined with the help of the frequency response method (method for determining the response to different frequencies or frequency response method) can be determined, whereby the microstructure test specimen with the help of a sinusoidal excitation force different Frequency is set in flexural oscillations. The amplitude of the excited or caused vibrations is then plotted as a function of frequency. From the curve obtained in this way, the dynamic Module E can be calculated from the following equation:

3. Ε = 4 · ίΓ ² .ί _ο · 1 · M / A,

where:

f = resonance frequency

1 = thickness of the structural test piece

M = total load; and

A = surface of the microstructure test piece.

The determination of the loss factor and the dynamic modulus is described in detail in "Mechanical Vibrations and Shock Measurements" by Jens Trampe Broch, published by Brüel and Kjaer.

The loss factor and the dynamic module of the component are strongly influenced by the properties of the resin binder.

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flows. In order for the component to have a range between 0.02 and The resin itself must be used to obtain a loss factor of 0/1 have a loss factor (peak values) between 0.1 and 0.5. Non-vitreous meet these requirements Resins. In contrast, vitreous resins have a loss factor of the order of magnitude of 0.001.

6 8 To one in the range between 10 and 10 units in the cgs system To achieve a lying dynamic module, the resin must show non-vitreous behavior in the required frequency range. Corresponding instructions or guidelines for the selection of resins are obtained from the glass transition temperatures.

Polyurethane prepolymer binder derived from polypropylene glycol and "crude MDI" (crude MDI is obtained by phosgenating the polyamines, which are produced by condensing formaldehyde with aniline arise in the presence of hydrochloric acid, and consists of diphenylmethane-4,4'-diisocyanate, polyphenyl polyisocyanates containing isomers and methylene groups with more than 2 isocyanate groups), represent suitable non-vitreous binders, their non-vitreous in the frequency range from 100 Hz to 10 Hz Maintain state.

Structural elements in the form of shields, walls, floors or ceilings can be manufactured or cast or shaped on the spot by placing a starting material / binding agent mixture in a shuttering or between shuttering boards, which has been carefully prepared beforehand, for example in a cement mixer. has been mixed, tamped down. Instead, the shields, walls, floors or ceilings can also be produced as preformed or pre-cast bricks or slabs. These bricks or slabs can be bonded together by using thin layers of a common mortar or organic binder, which can be the same as those used in the

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Manufacture of the components used to be connected.

Investigations by the applicant have also shown that the sound insulation properties the components or shields, walls, floors or ceilings according to the invention by backing or -clothing the elements with a layer of a relatively non-porous material can be improved. Have plaster of paris and cement proved to be suitable materials for this. The resulting improvement in sound insulation could be due to the Effect of internal multiple reflections that occur on the relatively non-porous Take place and interact with the room sound changed by the absorbing surface will.

The components, shields, walls, floors or ceilings can also be used in layered structures, for example with others Building materials. A laminate with rigid can be used as an example of such a layer construction Polyurethane foams are used. A laminate of this type can be used to produce lightweight panels with good sound absorption (and, if necessary, insulation). and at the same time good thermal insulation can be produced.

In the following the invention will be now described embodiments thereof, wherein all amounts and percentages are by weight.

EXAMPLE 1

"Flintag 5" (6CX) O parts), a flint starting material with a particle size of 850 μ, and a prepolymer (200 parts) obtained from polypropylene glycol (MW 10Q0) and "crude MDI" and having an iso-

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cyanate content of 20% was thoroughly mixed in a Hobart mixer. The mixture was in a metal mold poured or tamped and could harden there for 24 hours. The metal mold then became a structural member with a thickness of 50 mm taken. The device had a porosity of 0.45, one Air flow resistance of 42 units in the cgs system and following physical and acoustic properties.

Physical properties ;

Compressive Strength: 95 kgf / cm ² (1338 psi) Compression Modulus: 0.35. 10 ⁴ kp / cm ² (4.94 x 10 psi) Flexural strength: 53 kp / cm ² (750 psi) (Flexural strength)

Flexural modulus: 0.22 · 10 ⁵ kp / cm ² (3.2 · 10 ⁵ psi) (flexural modulus)

Tensile strength: 30 kp / cm ² (432 psi) (Tensile strength)

Tensile module:
(Tensile modulus)

0.22 * 10 ³ kgf / cm ² (3.2 x 10 ³ psi)

Acoustic data:

Statistical Ab
sorption coefficient
calculated from pipe
measurements * 0.05 0.26 0.48 0.47 0.76 0.65 0.8 < 0.82 0.87 0.75 0.87 0.95 Reverberation room test 100 200 300 0.65 500 0.85 700 - 0.85 0.85 0.90 4K Frequency (H ") 400 600 800 IK 2K 3K

* (Calculated Random Absorption Coefficient from tube measurement) This is a broadband absorber.

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EXAMPLE 2

A component with a thickness of 100 mm was made from the im Example 1 specified mixture produced in a similar manner as the component with 50 mm thickness. The 100 mm thick component was a good sound absorber and isolator. It had a loss factor ranging from 0.02 to 0.10 and

6 Q

a dynamic module in the range of 10 to 10 units in the cgs system.

EXAMPLE 3

The manufacturing process given in Example 1 was repeated, however, instead of "Flintag 5", the fabric "Flintag 6", a flint with a particle size of 500 µ, was used.

The 50 mm thick building element thus obtained had a porosity of 0.45, an air flow resistance of 72 units, measured in the cgs ^ system, and the following physical and acoustic data:

Physical Properties:

Compressive strength: 134 kp / cm Compression modulus: 0.28 Flexural strength:

Bending module:

Tensile strenght:

Tensile module:

(1903 p.s.i.)

10 ⁴ kg / cm ² (4 x 62 kg / cm ² (879 psi)

0.23 x 10 ⁵ kgf / cm ² (3.3 2

21 kgf / cm 0.26

(300 p.s.i.) (3.7

10 ³ kgf / cm ²

10 p.s.i.)

10 ⁵ psi)

1CT psi)

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Acoustic oatas:

Statistical Ab
sorption coefficient
(Pipe)
Frequency (Hz) 0.55
400 0.67
600 0.69
800 0.67
1K 0.78
2K 0.80
3K

This is a broadband absorber

EXAMPLE 4

A component with a thickness of 100 mm was made from the component used in Example 3 The mixture used was produced in a similar way to the 50 mm thick component.

The 100 mm thick component had good sound absorption and -isolation properties. It had a loss factor in the range of 0.02 to 0.10 and a dynamic modulus in the range

6 8
from 10 to 10 units, measured in the cgs system.

EXAMPLE 5

Garside 8/16 sand (1600 parts) and a two part epoxy resin system (80 parts) were carefully mixed in a Hobart mixer. The two-component epoxy resin system was obtained from "Epiphen" EL5 (100 parts) and the hardener (Hardener EHT3) (70 parts), the substances being manufactured by "Border Chemical Co., UK, Ltd." and "Epiphen" is a trademark. The mixture was poured or tamped into a metal mold and allowed to cure for 24 hours. A component that was 50 mm thick was then removed from the mold. The component had a porosity

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sity of 0.3, an air flow resistance of 14 cgs units and the following physical and acoustic data:

Physical properties :

Compressive strength: 122 kgf / cm. Compression modulus: 0.56

(1730 p.s.i.)

10 ⁴ kgf / cm ² (7.9

Flexural strength:
Tensile strenght:

56 kp / oiT (793 psi) 28 kp / cm ² (403 psi)

10 p.s.i.)

Acoustic data:

Statistical Ab
sorption coefficient
(Pipe)
Frequency (Hz) 0.26
400 0.48
600 0.79
800 0.93
1K 0.54
2K 0.80
3K

This is a narrow band absorber.

EXAMPLE 6

Garside 21 sand (3000 parts) and the prepolymer used in Example 1 (100 parts) were thoroughly mixed in a Hobart mixer. The mixture was poured or tamped into a metal mold and allowed to cure for 24 hours. A component that was 50 mm thick was then removed from this mold. The device had a porosity of 0.2, an airflow resistance of 154 cgs units, and the following physical and acoustic properties:

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Physical properties ;

Compressive Strength: 132 kp / cm (1874 p.s.i.)

4 2 Compression modulus: 0.32 x 10 kg / cm (4.6 *

10 * p.s.i.)

Flexural Strength: Flexural Modulus: Tensile Strength: Tensile Modulus:

73 kp / cnT (1038 p.s.i.) 0.19 * 10 ⁵ kgf / cm ² (2.76 x 10 ⁵ psi) 29 kg / cm ² (406 psi) 0.44 x 10 ³ kgf / cm ² (6.3 x 10 ³ psi)

Acoustic data:

Statistical Ab
sorption coefficient
(Pipe)
Frequency (Hz) 0.53
400 0.57
600 0.58
800 0.59
1K 0.67
2K 0.70
3K

This is a broadband absorber

EXAMPLE 7

A component with a thickness of 100 mm was produced from the mixture used in Example 6 in a manner similar to that of the 50 mm thick component. The 100 mm thick component was a good sound absorber and isolator. It had a dissipation factor ranging from 0.02 to 0.10 and a dynamic modulus

6 8
in the range of 10 to 10 units, measured in the cgs system.

EXAMPLE 8th

2
A 3.3 m test wall was built into a standard test opening in a reverberation unit. The reverberation unit was built up from 200 ηα 50 mm 100 mm large bricks, which were produced according to Example 1. With this measuring

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device, the sound reduction index was measured at different frequencies. The results are obtained from the graph in FIG. 1. At 500 Hz, a sound insulation index of 17 dB was found; this value is below the average sound insulation value.

The experiment was carried out with a back deposited or
-clad wall repeatedly, the wall cladding consisting of an approximately 12 mm thick layer of plastered "Carlite" plaster. The results obtained with this test wall are shown in FIG. A sound insulation index of 43 dB was achieved at a frequency of 500 Hz. This is good sound insulation.

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Claims (22)

PAXENT SPEECH 1. Load-bearing, sound-absorbing structural element with a thickness of at least 50 mm, characterized by a rigid, open-cell structure produced by binding a starting material with a porosity in the range from 0.15 to 0.7 and an air flow resistance in the range from 10 to 180 cgs units. 2. The component according to claim 1, characterized in that the The starting material is sand, flint or granite. 3. Component according to claim 1 or 2, characterized in that the starting material does not exceed a 2, O mm Has particle size. 4. The component according to claim 1 or 2, characterized in that the particle size of the starting material between O, 5 and 2 mm. 5. Component according to one of claims 1 or the following, characterized characterized in that the starting material is bound with a curable resin binder. 6. The component according to claim 5, characterized in that the binder is a polyurethane, epoxy or unsaturated polyester resin. 7. Component according to one of claims 1 to 4, characterized in that the starting material with sodium silicate or Phosphate binder is bound. «09«? 6 / 0Et · ^{0RIGINALINSPECTED} 27523U 8. Component according to claim 1 or following, characterized in that the bound starting material consists of a starting material / binder mixture which was mixed together in a starting material / binder ratio of 2O: 1 to 6O: 1 . 9. Load-bearing component that operates in the frequency range from 1OO Hz to 4th
10 Kz absorbs and isolates the sound and has a thickness of at least 100 mm, characterized by a rigid, open-cell structure made of a bound starting material with a porosity in the range from 0.2 to 0.7 and a porosity in the range from 40 to 180 cgs -Units lying air flow resistance, wherein the starting material is bound with a resin binder, which has non-glass-like properties in the sound frequency range to which the wall is to be exposed. 10. The component according to claim 9, characterized in that the resin binder is a polyurethane prepolymer obtained from polypropylene glycol and "raw MDI". 11. Use of the component according to one of claims 1 or the following for the production of shields, walls, floors or ceilings. 12. A method for producing a component according to one of claims 1 or the following, characterized in that the Starting material and a binder are mixed and this mixture hardens in a mold or between shuttering boards. 13. Shielding, wall, floor, ceiling or the like, characterized in that it is built up from brick or plate-shaped components according to one of claims 1 to 1O in such a way that the components are through thin layers of a 809826/05 * 8 common mortar or an organic binder. 14. Screening, wall, floor, ceiling or the like Claim 13, characterized in that the binding agent for connecting the individual components is identical to one another the binder used to manufacture the components themselves. 15. Component according to one of claims 1 to 10, characterized in that that it has a layer of a relatively non-porous material on a rear side. 16. shielding, wall, floor, ceiling or the like according to claim 13 or 14, characterized in that the rear side thereof comprises a layer of a relatively non-porous material. 17. The component according to claim 15, characterized in that the rear layer is plaster of paris or cement. 18. Shielding, wall, floor or ceiling, characterized in that that the back layer is plaster of paris or cement. 19. Component according to one of claims 1 to 10, characterized by layers of another building material. 20. shielding, wall, floor, ceiling or the like according to claim 13, 14 or 15, characterized by layers of another building material. 809826/0548 -vt- 21. The component according to claim 20, characterized in that the other building material is rigid polyurethane foam. 22. shielding, wall, floor or ceiling according to claim 20, characterized in that the other building material is rigid polyurethane foam. 809826/054 $