AU686857B2 - Improved lining materials for buildings - Google Patents

Description

I "IMPROVED LINING MATERIALS FOR BUILDINGS" This invention relates to lining materials for use in buildings and has been devised particularly to provide lining materials with useful sound absorbing and fire protection properties for use in wall and ceiling applications. As used herein, the term "lining material" means a flexible or semi-flexible non-load-bearing material which in use is secured to a suitable support.

It is well known that water sprinklers may be fitted to the interior of buildings and that these are effective following the outbreak of fire in containing or even extinguishing fire and thus reducing the fire hazard both in terms of damage and risk to occupants. To further reduce the hazard many buildings are divided into compartments or fire cells, each separated from the other by a construction with known fire resistance 0 S when tested in accordance with recognised standard fire resistance tests.

Nevertheless, for various reasons many buildings are not fitted with water sprinklers at all, and in these particularly the reaction to fire of the linings needs to be considered very carefully. As well as the recognised standard fire resistance tests, standard tests are also used to determine the reaction to fire of linings of buildings, and in New Zealand at present the test used is Australian Standard 1530 Part 3, which is commonly known as the Early Fire Hazard Test.

The Early Fire Hazard Test simultaneously determines the ignitability, flame propagation, heat release, and smoke release of materials and in New Zealand, emphasis is placed on flame propagation and smoke release particularly, because these have been found from experience to be the main hazards to life during the developing stages of a fire when the occupants have the opportunity both to escape and to summon assistance.

To meet the utility requirements in many buildings it is also desirable or necessary to provide good acoustic properties both to reduce sound transmission between

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~Rllb raarrrrrra~- lan~na~warrrcm~ a~~ rooms (Sound Transmission Coefficient STC) and to reduce sound reflection within a particular room, The NRC or noise reduction coefficient of a lining material is its ability to absorb sound energy and not to re-radiate it back into the room, and this property depends upon the ability of the material to allow sound to enter the structure of the material where the sound energy can be absorbed within it, The corrunon example of such a material is the so called "acoustic tile" which is usually made of a relatively soft wood or mineral fibre substrate with a perforated face. Acoustic tiles function by allowing the sound to enter the structure through the perforations or holes, where the energy is partially absorbed within the mass of the material as the sound waves travel ULJ: back and forth within the holes, Materials such as wool, polyester fibre, or wood fibre, either in the form of a S felted or needle punched blanket, or bound with a suitable binder are useful for S" incorporation into assemblies with good acoustic functions, but they have the serious disadvantage that they are unacceptably combustible for many applications. Also in this category are various polymer foam materials such as synthetic and natural rubbers, and urethanes for example, which although they can be modified to some extent to reduce the fire hazard still have a high flame propagation when ignited, andlor a high smoke release, when subjected to the Early Fire Hazard test. These materials also need to have an aesthetically acceptable surface applied before they are suitable for use, and this can also add to the fire hazard.

In our experience in the manufacture of building and acoustic control materials we have found that there is an unfilled need for an acoustic lining material with good appearance and good fire protective properties, particularly a Spread of Flame Index of 2 or less, and a Smoke Developed Index of 5 or less, when subjected to the Standard I L~ Test, Australian Standard 1530 Part 3, commonly known as the Early Fire Hazard Test.

Such acoustic lining materials have applications in recording studios, halls, cinemas, auditoria, and lecture rooms and schools for example. While it is not particularly difficult to provide any one of the appearance, Early Fire Hazard, or acoustic attributes separately it becomes very difficult to provide all three in the one material, It is therefore an object of this invention to provide lining materials which have useful acoustic and fire performance properties, together with a pleasant appearance.

It is a further object of this invention to provide lining materials for buildings which overcome some of the forgoing disadvantages, or at least provide the public with la: a useful choice.

According to one aspect of this invention there is provided an acoustic lining material including: a first layer consisting of at least one acoustic absorbing substrate material selected from the group: wool fibre, polymer fibre, rubber foam, polymer foam, blends thereof; said layer having a thickness in the range 6 mm 150 mm; the or each said material having a density in range 5 50 kg per cubic metre; a second layer consisting of a non-combustible (as hereinbefore defined) heat shielding material selected from the group: woven glass, felted glass, mineral fibre, ceramic fibre, blends thereof; said layer having an uncompressed thickness in the range 0.15 1,5 mm; a third layer consisting of a decorative and/or protective material selected from one or more of the group: paint, plaster coating, floe coating, woven fabric, felted fabric, melded fabric, paper, metal film, polymer film; said layers being laminated together to form a composite sheet, with said second layer sandwiched between said first and third layers.

For some applications, a double-sided product is required, e.g. for a hanging baffle. Such a product can be made by laminating a layer of non-combustible heat I ill shielding material to each side of the acoustic absorbing substrate material, with a layer of decorative and/or protective material laminated over each layer of heat-shielding material.

The at least one acoustic absorbing substrate material may be a blanket of wool or polymer fibres, or a blend thereof, for example, which may be felted or needle punched as known in the art to impart a degree of tensile strength perpendicular to the faces (the property sometimes referred to as "internal bond") to prevent internal delamination. Alternatively such blanket may be bonded with a suitable adhesive such as a latex or synthetic polymer binder. Preferably when a binder is used to bind the .io.4 acoustic absorbing substrate material it is of an elastomeric type rather than a rigid type.

Typically these blanket acoustic absorbing substrate materials will have a density towards S. the lower end of the range given, that is between 5 and 25 kilograms per cubic metre for example, although densities outside this range may also be used.

The at least one acoustic absorbing substrate material may also be a rubber or polymer foam structure with open or closed cells, e.g. a natural or synthetic rubber compound such as a butyl or nitrile rubber for example, or a urethane, polyethylene or polypropylene for example, or a co-polymer of these materials, These are examples only of suitable foam materials, and other rubbers or polymers with open or closed cell structures may also be used. Preferably, but not essentially, the foam may be modified by addition of fire retardant compound or compounds such as melamine or other nitrogen donor additive, or alumina tri-hydrate or other water donor additive for example. Typically these foam acoustic absorbing substrate materials will have a density towards the higher end of the range given, that is between 25 and 50 kilograms per cubic metre for example, although densities outside this range may also be used.

c When the Early Fire Hazard performance is considered, the nitrile rubber foam may have a superior performance, but is too costly for most applications. With the possible exception of nitrile rubber foam, even when the acoustic absorbing substrate materials nominated are treated with fire retardant they can still often burn with a high flame propagation (Spread of Flame Index) and a high smoke density (Smoke Developed Index) after ignition.

The thickness of the at least one acoustic absorbing substrate material is determined by a balance between utility and cost. Thicknesses within the range 6mm to 18mm provide some useful acoustic absorption properties, particularly when they are 1a: retrofitted to existing walls in the form of an "acoustic upgrade" for example, when the thickness may be as little as 6 mm. For most purposes a thickness range of between 1 2mm and 50mm is suitable. To meet even more critical requirements, especially where low frequency sound absorption is required, thicknesses of 100 mm and occasionally 150 mm are necessary. These thicker materials may be either laminated-up from thinner stock, e.g. 50mm or may be cut directly from slab. As the thickness of the at least one acoustic absorbing substrate material is increased it has the disadvantage of occupying an increasing amount of volume in the room, and this has to be balanced in relation to the importance of improving the low frequency absorption characteristics to meet the a needs of a particular application.

The at least one acoustic absorbing substrate material may be in the form of one layer only, or may be laminated from a plurality of layers to make up a greater thickness, and all layers need not be the same. For example, laminating a plurality of layers wherein the layers are of different density can improve the useful acoustic absorption characteristics of the substrate material. Optionally two similar substrate material layers

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ray be laminated together with a relatively thin energy absorbing layer of denser material at the interface between the two substrate material layers. The optional relatively thin energy absorbing layer may be from 3 millimetres to 7 millimetres thick, and with a density depending upon thickness to give a mass of between 4 kilograms and 8 kilograms per square metre of area. It is advantageous to adjust the mass per square metre within the range given depending upon the acoustical results required. The higher density may be achieved by loading a rubber or polymer with a heavy clay, sand, or oxide filler such as barium or iron oxide, or with metallic particles for example. A plurality of layers including the relatively thin energy absorbing layer of denser material as described has the advantage that sound energy is absorbed by the denser layer which is effectively acoustically isolated by the lower density layers of the at least one acoustic absorbing substrate, thereby serving the dual function of absorbing the 7-.oustic energy while avoiding transmitting it either forward again into the room, or backward to the wall structure behind. Depending upon the cost-effective result required in a particular application the acoustic absorbing substrate material may be comprised of either one or a plurality of layers laminated together, The at least one acoustic absorbing substrate material, whether in the form of one layer or a plurality of laminated layers, with or without a relatively thin sheet of denser material at an interface, has laminated to at least one face, a non-combustible heat shield layer. As used herein, "non-combustible" means that preferably the heat shield layer, when tested in accordance with the Standard Tests, either AS 1530 Part 1, or BS 476 Part 4, is classified as non-combustible, although materials with up to 10% by mass of a combustible binder are suitable for the purpose. Suitable non-combustible heat shield layer materials include fibreglass, mineral fibre, and ceramic fibre for example, in

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the form of cloth or felt, with or without a binder material such as phenolic resin or other suitable binder. The density of the heat shield layer material is not narrowly critical, but within the thickness range 0.15 millimetres and 1.5 millimetres the thicker material provides a better heat shield function, as might be expected. The thicker material is usually more costly however, and in Early Fire Hazard tests thicknesses within the range 0.15 millimetres and 0.75 millimetres function effectively without being excessively costly.

The decorative and protective surface layer of the laminated acoustic lining material may in its simplest form be a surface coating applied directly to the aI: non-combustible heat shield layer. The surface coating may be a paint such as a latex water based, or a solvent alkyd based paint finish, or a plaster mix, possibly with the addition of macerated polystyrene. The finish is either factory applied to the heat shield layer, or applied to the laminated assembly after it has been installed in a building. This form of the invention with the surface coating factory applied has been found particularly suitable for use in ceiling applications. Where a smooth surface is required a layer of lignocellulosic paper of between 40 and 120 grams per square metre basis weight may be applied to the heat shield layer surface before applying the surface coating. A decorative paper may also be used, such as a printed and/or embossed paper, which may a be prefinished before laminating to the heat shield layer, T h e decorative and protective surface layer of the laminated acoustic lining material may optionally be in the form of a fibre floe with fibre lengths between 0.25 millimetres and millimetres. The fibre floc may be applied directly to the heat shield layer, or more preferably to the heat shield layer after it has been either prime coated with a paint coating or had paper applied as previously described for a painted surface. Electrostatic

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application apparatus is known to those skilled in the art, and this may be used to advantage to apply the fibre floc. Floe made from any suitable fibre may be used, including nylon, polypropylene, natural wool, or polyester for example.

The decorative and protective surface layer of the laminated acoustic lining material may be in the form of a felted or melded fabric, By melded, we mean a sheet of non woven fibrous fabric material, felted or dry formed, and which has been pressed and heated sufficiently to produce a plurality of fused connections between adjacent fibres, thus developing an internal bond in the fabric. Suitable prior art fabrics of this type are available where fibre blends are used, it being appreciated that at least one of 1A: the fibre types in the blend must be capable of softening or fusing sufficiently during the hot pressing process to develop the necessary bond. Fibre types which may be used in this type of fabric include nylon, polyester, and polypropylene for example, such as a nylon and polyester blend, The decorative and protective surface layer of the laminated acoustic lining material may be in the form of a woven fabric. Many types of woven fabric are suitable including wool, polyester, polyester and cotton blends, rayon, and viscose for example, more preferably when the basis weight of the woven fabric is within the range 40 to 350 grams per square metre, Most textile fabrics can be used.

Surprisingly, the decorative and protective surface layer does not need to be of a fire retardant material as might first be expected:- numerous Early Fire Hazard tests show that the decorative and protective surface layers, when combustible, tend to burn near the source of ignition but do not propagate fire beyond the immediate region where they are ignited during the test. Typically a zero Spread of Flame Index is obtained and a Smoke Developed Index of between 3 and 5. These indices are particularly useful for I lining materials intended for building interiors in New Zealand and Australia, The smoke release can be controlled and reduced if necessary by including a water releasing agent filler such as alumina tri-hydrate in the adhesive used to adhere the decorative and protective surface layer to the heat shield material. Amounts of between 20% and by mass, based upon the mass of the unfilled adhesive may be included when it is necessary to reduce the smoke release.

Aiy suitable interior-durable adhesive may be used to laminate the various components together, depending upon the production facilities available. The same adhesive type need not be used at every glueline. Water based latex adhesives designed

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i to have a quick grip may be used for example, especially if the production line includes warmed rollers or a radiant heat facility to help in bond development. Starch based and modified starch based adhesives may also be used. We have found solvent based chloroprene adhesives particularly advantageous in spite of their cost because the rapid flash-off of solvent allows for higher line speeds and therefore lower factory costs. Any suitable adhesives may be used however, By way of example only, the following are results of Early Fire Hazard tests

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(Australian Standard 1530 Part 3) on a laminated acoustic lining material prepared in accordance with the invention. The at least one acoustic absorbing substrate material was

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a single layer of polyurethane foam having a density of between 30 and 35 kilograms per 2 o cubic metre and a thickness of between 24 and 26 millimetres. The heat shield layer was felted fibreglass bound with a phenol formaldehyde synthetic resin and having a relaxed thickness of between 0.5 and 0.8 millimetres. The decorative surface layer was a pure wool textile fabric of between 260 and 280 grams per square metre.

Laminated material was prepared using both water based and solvent based adhesives for laminating, with the adhesive modified by addition of alumina tri-hydrate in each case.

The results are as shown below, The figures in brackets are the indices achieved relative to the scales set in the Australian Standard 1530 Part 3.

Water based Index Solvent Based Index adhesive adhesive Time to ignition (seconds) 303 (15) 318 Heat Release (kJ/m 9 2 (0) 1o Flame Propagation (seconds) 0 0 (0) Smoke release (logioD) 0.136194 0.155369 The indices remained the same using both types of adhesive, and according to a the laboratory conducting the tests the small variation seen between the two types is within the range normally seen with this test. The conclusion based upon the results is that there is no significant difference between the performance of the two adhesive types.

Furthermore the zero flame propagation (and zero Spread of Flame Index) is considered an excellent result for the material. The smoke release is at the lower end of the range 0,131 to 0.262 logoD allowed in the Standard Test AS1530 Part 3 1989 for a five Smoke Developed Index. A five Smoke Developed Index is permitted for most interior surfaces of buildings in New Zealand.

This invention has been described by way of example only and equivalent materials to those disclosed will be known to persons skilled in the art, and these are included within the scope of the invention. The invention fills a need for lining materials with a combination of useful fire and acoustic performance properties at reasonable cost.

Claims (19)

1. An acoustic lining material including: a first layer consisting of at least one acoustic absorbing substrate material selected from the group: wool fibre, polymer fibre, rubber foam, polymer foam, blends thereof; said layer having a thickness in the range 6 mm 150 mm; the or each said material having a density in range 5 50 kg per cubic metre; a second layer consisting of a non-combustible (as hereinbefore defined) heat shielding material selected from the group: woven glass, felted glass, mineral fibre, ceramic fibre, blends thereof; said layer having an uncompressed thickness in the range za: 0.15 1.5 mm; Sa third layer consisting of a decorative and/or protective material selected from one or more of the group: paint, plaster coating, floe coating, woven fabric, felted fabric, melded fabric, paper, metal film, polymer film; said layers being laminated together to form a composite sheet, with said second layer sandwiched between said first ard third layers. 0*

2. The acoustic lining material as claimed in claim 1, further including a further second layer and a further third layer; said layers being laminated together with a second layer secured to each side of said first layer, and a third layer secured over each second layer.

3. The acoustic lining material as claimed in claim 1 or claim 2, wherein said first layer comprises two or more layers of acoustic absorbing substrate materials laminated together.

4, The acoustic lining material as claimed in claim 3 wherein each of said two or more layers are of different density.

The acoustic lining material as claimed in claim 4 wherein said first layer comprises a layer of relatively dense material sandwiched between two layers of less dense material.

6. The acoustic lining material as claimed in claim 5 wherein said layer of relatively dense material has a thickness in the range 3 7 mm and a density such that the mass 1o: is in the range 4 8 kg per square metre. *9. .:4 *r

7. The acoustic lining material as claimed in any preceding claim, wherein said first layer comprises or includes a blanket of fibres selected from the group: wool, polymer, wool/polymer blends; said fibres being felted together,

8. The acoustic lining material as claimed in any one of claims 1 6 wherein said first layer comprises or includes a blanket of fibres selected from the group: wool, polymer, wool/polymer blends; said fibres being needle-punched together, 4

9. The acoustic lining material as claimed in any one of claims 1 6 wherein said first layer comprises or includes a blanket of fibres selected from the group: wool, polymer, wool/polymer blends; said fibres being bonded together by an adhesive binder.

The acoustic lining material as claimed in claim 9 wherein said adhesive binder I- I is an elastomer.

11. The acoustic lining material as claimed in any one of claims 1 6 wherein said first layer comprises or includes an open-cell foam.

12. The acoustic lining material as claimed in any one of claims 1 6 wherein said first layer comprises or includes a closed-cell foam.

13. The acoustic lining material as claimed in claim 11 or claim 12 wherein said foam includes a fire retardant additive.

14. The acoustic lining material as claimed in any one of claims 11 13 wherein said foam further includes a filler selected from the group: clay, sand, barium oxide, iron oxide, metallic particles.

•15. The acoustic lining material as claimed in any preceding claim wherein said second layer is in the form of a cloth. .o 4444*

16. The acoustic lining material as claimed in any one of claims 1-14 wherein said second layer is in the form of a felt,

17. The acoustic lining material as claimed in claim 16 further comprising a binder material for securing the felted fibres together. I

18. The acoustic lining material as claimed in any preceding claim wherein said first, second and third layers are laminated together with adhesive.

19. The acoustic lining material as claimed in claim 19 wherein said adhesive is selected from the group: water-based latex adhesive, starch- and modified-starch-based adhesive, solvent-based chloroprene adhesive. The acoustic lining material as claimed in claim 1 and as hereinbefore described with reference to the foregoing Example. e *e S a II Absa= An improved Uning material which has sound absorbing and fire protection properties as well as being of aesthetically acceptable appearance, The lining material is a composite consisting of at least three layers laminated together:- a first layer which is an acoustic absorbing material, a second layer which is a non-combustible heat shielding material and a third decorative and/or protective layer; the layers are laminated together with the second layer sandwiched between the first and third layers. Does 0:00 0004 60099: 0 0