CA2033955A1 - Fiber reinforced thermoplastic composites as fire/heat barriers for combustible substrates - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A fire resistant structure has a compressed fiber reinforced composite layer and a wooden substrate layer. The composite layer upon exposure to fire provides a lofted glass network which acts as a barrier to heat and fire thereby protecting the underlying substrate layer.

Description

~t~ 3 FIBER REINFORCED THERMOPLASTI~ COMPpSI~ES
AS FIRE/HEAT BARRIERS _QB ÇOMBUSTIBLE SUBSTRATES
Walter L. Hall Erich O. Teu~sch BACKGRO~ND QF THE INVENTIO~
Field of the_Invention The present invention relates to fire resistant structures, and more particularly r~lates to multilayered structures having a fiber reinforced protective layer and a protected substrate layer.
De~i pti on of Re~ a~ed Art 5Structural materials such as sheets of wood, plywood, particle board, and oriented strand board find wide spread use in the building industry. Each of these materials, while providing desired levels of strength and economy, have, however, generally lo exhibited undesirably low levels of heat and fire resistance.
Accordingly, one object of the present invention is to provide wooden structures which exhibit desired levels of heat and fire resistance.
SUMMARY OF THE INVENTION
15The present invention provides a fire resistant structure having a compressed fiber reinforced composite layer and a wooden substrate.
DETAILED DESCRIPTION OF THE INVENTION
The fire resistant structures of the present invention have a compressed, fire resistant 20composi te 1 ayer and a protected wooden substrate layer.
The fire resistant composite layer has respective amounts of (i) fire resist~nt fibers and ~ii) a binder material.
25The fi re resi stant fi bers are preferably in the form of single discrete fibers and preferably have a 2 ~ ~, 3 ~3 ~ j 08i::T04963 high modulus of elas~ici~y. The fire resistant fibers preferably neither melt nor lose their high modulus of elastici~y at temperatures below 400~C, and more preferably 600C. Suitable fibers include glass, carbon, mineral and ceramic fibers and certain polymeric fibers such as aramid ~ibers sold under the trade names Kevlar and Nomex. Preferably, the fibers have a modulus of elasticity hiyher than 10,000 Mega Pascals.
lo Suitable fibers have at least 50% by weight fiber strands having a length between about 0.125 inch and about 1.0 inch, more preferably between 0.125 and 0.5 inch, and most preferably about 0.5 inch. The fibers preferably have an average diameter of from between 2 microns and 30 microns, more preferably between 12 microns and 23 microns and most preferably about 16 microns. Fiber length is important in providing the desired level of lofting in structure upon exposure to heat. Fibers which are either too long or too short provide inadequate levels of lofting. Fiber diameters are important in providing the desired levels vf fiber stiffness~ Fibers which are too thin lack the desired levels of stiffn~ss for lofting and fibers which are too thick are also generally ~oo stiff and break during compression.
The birder material is prefer2bly an organic material and may be selected from resins including both thermoplastics and thermosets. The binder 30 material upon consolid~tion forms a solid matrix ~hich serves to bond the fibers toge~her in the composi te 1 ayer. The bi nder preferably is a thermoplastic material.
Suitable thermoplastic materials for forming a binder matrix inolude polyolefins, polyesters, 6~3) ~,3' r~
OaCT~ 49 63 polyamides, polyethers, polycarbonates, acrylonitrile styrene-butadiene copolymer, polyvinylchloride, and polystyrenes.
Sui tabl e pol yol e~i ns include a polymerization 5 produc~ of at least one aliphatic ethyleneically unsaturated monomer and is selected from polyethylene and other ~olyolefins and copolymers of such monomers, for example, polyethylene, polybutene, polypropyl ene, polypentene, poly~methylpentene~, normally solid copolymer of ethyl ene and butene-1, copolymers of ethylene and ethyl acrylate, or vinyl acetate, butadiene-acrylonitrile copolymers, ionomers, poly(methyl methacrylate), polyisobutylene rubbers and the like, poly(vinyl chloride), poly(vinylidene chloride), a copolymer of vinyl chloride with vinyl acetate, natural rubber, a rubbery copolymer of butene-1 and ~thylene, a rubbery copolymer of butadiene and acrylonitrile, and the like. All such polymers are commercially available or can be prepared by techniques well known to those skilled in the art. As ~o ~he copolymers and terpolymers, the proportions of the repeating units may vary broadly and will be selected to provide the desired characteristics, i.e., normally ru~bery, normally solid, and the like. In addition to the polymers illustrated above, other suitable polymerization products of aliphatic ethyleneically ~nsaturated monomers include derivatives thereof, sueh as 3Q halogenated hydrocarbon polymers, e.g., chlorin~ted polyethylene, chlorssulfonated polyhydrocarbons and polymerized carboxy-substituted butadiene and the like.
Other preferred thermoplastics are selected from polyacetal homopolymers, such as ~r~i .? ~
osc~o~s63 polyoxymethylene, polyacetal copolymers, such as those based on trioxane, polyphenylene ethers, such as poly(2,6-dimethyl-1,4-phenylene)ether, polysulfones, such as the condensation product of bisphenol A and 4,4'-dichlorodiphenyl sulfone, polyamides, such as polycaprolactam, or the product of hexamethylenediamine and adipic acid, polyimides, e.g., the product of bismaleimido diphenyl methane and methylene dianiline, normally solid or normally lo rubbery polyorganosiloxanes, such as polyalkyl or aryl-siloxanes, or combinations of the two, and copolymers of polyorganosiloxanes with vinyl aromatics, e.g., styrene, acrylic monomers, e.g., methyl methacrylate, or aromatic esters, e.g., ~he 15 reaction products of bisphenol A and iso or terephthaloyl chloride, as well as siloxane-nitrogen copolymers containing amido, amide-imido and imide groups. All such polymers are either commercially available or can be made in ways known to those skilled in the art.
Also preferred are ~hermoplastics which comprise mixtures of any of the above-mentioned thermoplastics. For example, one such mixture would comprise a high molecular weight composition which is a combination of polystyrene or other styrene resin, including rubber modified polystyrenes (i ) with a condensation product of 2,6-dimethylphenol, i.e., poly(2,6-dimethyl-1,4-phenylene)ether.
Typi cal of the polyester resi ns sui tabl e for 30 this invention are poly(alkylene terephthalates, i sophthal ates or mi xed terephthal ~tes and i sophthal ates ), wherei n the al kyl ene groups contai n from 2 to 10 carbon atoms. They are avai 1 abl e commercially or can be prepared by known techniques, 35 such as by the alcoholysis of esters of the phthalic ~ ~ 3 ,~

acid with a glycol and subsequent polymerization, by heating glycols with the free acids or with halide derivatives thereof, and similar processes. These are described in U.S. Patent No. 2,465,319 and 3,047,539 and elsewhere.
Although the glycol portion of such typical polyesters can contain from 2 to 10 carbon atoms, e.g.p 1,2 ethylene, 1,3-propylene, 1,4-butylene, 1,3-butylene, 1,2-propylPne, 1,2-butylene, 2,3-butylene, 1,6-hexylene, 1,10-decylene, etc., it is preferred that it contain 2 or 4 carbon atoms, in the form of linear methylene chains.
Preferred polyesters will be of the family consisting of high molecular weight, polymeric 1,4-butylene glycol terephthalates or isophthalates having repeating units of the yeneral formula:
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~(CH2)4--O--C~ ~,C--O }

and mixtures of such esters, including copolyesters of terephthalic and up to about 30% isophthalic acids.
Especially preferred polyesters are polye~hyleneterephthalate, poly(1,4-butylene 70/30 isoterephthalate) and poly(1,4-butylene terephthalate). Speeial mention is made of the latter because it is easy to prepare from readily available materials and crys~allizes at an especially rapid rate.

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Illustratively, sufficiently high molecular weight polyesters of the preferred type wi 1 1 have an intrinsic viscosity of at least 0.2 and preferably about 0. 4 deciliters/gram as measured in o-chlorophenol, a 60/40 phenol -tetrachl oroethane mixture or a similar solvent at 25-30C. The upper limit is not critical, but will generally be about 1. 5 dl . tg . Especi al ly preferred polyesters wi l l have an intrinsic viscosity in the range 0.5 to 1.3.
Suitable aromatic polycarbonate resins are the polymers derived from a bivalent phenol and a carbonate pre-product, for example phosgene, a halogen formate or a carbonate ester. The aromatic polycarbonate resins preferably possess an intrinsic viscosity of approximately 0.35-0.75 (measured in p-dioxane at 30C and expressed in deciliters per gramO. Suitable bivalent phenols which may be used for the preparation of ~hese aromatic polycarbonate resins are mononucleus and multinuclei aromatic 20 compounds which comprise 2-hydroxyl groups as functional groups which are both directly bonded to a carbon atom of an aromatic nucleus. Examples of suitable bivalent phenols are: 2,2-bis(4-hydroxy-phenyl) propane (Bisphenol A = BPA), resorcinol;
25 bis~4-hydroxy-s-nitrophenyl) methane;
2,2'-dihydroxydiphenyl; 2,6-dihydroxynaphthalene;
bis-(4-hydroxy-phenylsulfone); 5'-chloro-2,4'-dihydroxyldiphenyl sulphone, 4,4'-dihydroxydiphenyl ether, and 4,4'-dihydroxy-2,5-diethoxydiphenyl ether.
In preparing the aromatic polycarbonate resins it is possible to use two or more different bivalent phenols or a copolymer of a bivalent phenol with a glycol or with a polyester with hydroxy group or acid terminal group. The aromatic polycarbonate 08cq~04963 _ 7 _ resin may also be prepared in the presence of a dibasic acid. Crosslinked polycarbonate resins as described in U.S. Patent No. 4,001,184 are also suitable. It is also possible to use a mixture of two or more of the ahove-mentioned polycarbonate resins. The homopolymer derived from bisphenol A is preferably used as a polycarbonate resin.
Upon exposure $o heat and flames, the binder material burns, decomposes or experiences reduced viscosity resulting in the release of the fiber web allowing ~he web to loft. Generally, the longer the fiber length for randomly dispersed glass fibers the greater the web will loft and the greater the web will protect the substrate. In other words, the longer the fibers in a randomly dispersed compressed fiber system, the greater the degree of loft obtained upon decompression. The c~mpressed composite layers are made by the binder material and fibers being randomly dispersed to ~orm an 20 unconsolidated, lofted web, which is then consolidated by heat and pressure into a solid continuous form. The pressure causes the fibers to be compressed, and the heat, in the case of thermsplastic binder materials, serves to melt the 2s thermoplastic which then flows around the fibers and upon cooling forms ~ solid matrix which locks ~he fibers into a compressed state. Suitable compressed composite layers ~re set forth i n European Patent Applica~ion 0,148,761 filed January 3, 1985 and published July 17, 1985.
As mentioned above, the preferred binder ma~erials are thermoplas-tics. Preferably the thermoplastic is, prior to dispersion and consolidation, in the form of a fine powder or particulate. The plasties may also be in a needle o ~ J t~ 3 or fibrous form prior to dispersion and consolidation. The fibers and thermoplastic powder or particulates can be randomly dispersed to form a lofted web by any of various well known dispersion processes including dry blending, aqueous dispersion, latex dispersion and foam dispersion processes. Suitable processes are set forth in Uniked Kingdom Patent 1,129,757, United Kingdom Patent 1,329,409, European Patent Application 0,148,760, European Patent Application 0,148,761, U.S. Patent 4,426,470, and U.S. Patent 3,716,449, all of which are incorporated herein by reference.
Extrusion processes involving the mixing of fibers and thermoplastics are generally not suitable in 15 that they lead to substantial breakage of the fibers resulting in fibers of insufficient length for the desired level of lofting. The above dispersion processes result in the formation of a web of randomly dispersed fibers in thermoplastic powder.
The web is initially an unconsolidated web which is in a generally uncompressed state, lofted, and in the form of a mat. De~ining the unconsolidated web as being in a generally X, Y plane, the randomly dispersed fibers generally have degrees of 2s orientations in e~ch of the Xr Y and Z direction, th~ Z direction being perpendicular to the XY plane.
While the fibers may be primarily oriented in the XY
plane they generally have some degree of orientation in the Z direction. Having a degree of orientation in the Z direction can facilitate the fibers being in a lofted state giving the web an initial unconsolidated thickness and a relatively low volume fraction of glass. Upon being compressed to a compressed state, the fibers will, due to their high modulus of elas~icity, exert forces in the Z

g /I. '".' i^3 OE~CT04963 _ g _ direction in an effort to return the web to its i ni ti al unconsol i dated thi ckness . Thus, when the unconsolidated web is heated and compressed and then cool ed, the bi nder matrix upon sol i di f i cati on hol ds the compressed fibers in a compressed state thereby providing a relatively thin compressed composite layer. Later upon exposure of the composi te 1 ayer to high levels of heat or flames, the binder matrix mel ts or burns allowing the fi bers to loft in the Z
lo direction thereby forming a thick lofted web of heat resistant fibers whi ch act as a hea~ and fi re barrier ~or the underlying substrate.
It is also believed that the lofted heat resistant fiber web provides reduced oxygen access 15 to the underlying substrate thereby reducing the substrate's tendency to burn. Additionally, it is believed that the lofted fiber web provides for more complete combustion of hydrocarbons passing therethrough resulting in reduced smoke levels during burning of the structure as compared to burning of an unprotected substrate.
Substra~e layers ~or ~he struc~ures of the present invention include wood substrates and plastic foam substrates.
The wood substrate layers may be any wood based material. Specifically, preferred wood based materials include solid wood, for example pine~ oak, cedar and fi r boards, parti cl e board, oriented strandboard, flakeboard and plywood, These wood products ar~ well known in the building industry.
Plastic substrate layers employed in th~
building industry i ncl ude vari ous i nsul ati ve pol ymer foams including polystyrene foams and polyethylene foams, polypropylene foams, polyurethane foams and crosslinked polyethylene ~oams.

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08C!T04963 Both the wood substrate layers and the plastic foam substrate layers need protection from heat and flames.
The structures have a composite layer attached to a substrate layer. Suitable means for attaching the composite layer to the substrate layer in~lude mechani cal attachments such as clamps, screws, nails, bracke~s, frames and staples; and chemical adhesives such as thermoset and thermopla~tic lo bonding agents i ncl udi ng gl ues and epoxies. The chemical adhesives are preferred.
Unconsidated webs prior to consolidation have a desired glass density which is defined as the amount of glass per unit volume of unconsolidated web.
Preferably the glass density is from 0.03 g/cm3 to 1.5 ~/cm ; more preferably from 0.05 gJcm3 to 0.09 g/cm , and most preferably about 0.07 g/cm3; and preferably the unconsolidated webs have a thickness of ~rom 0.2 inch to 5 inches, more preferably from 0.5 inch to 2 inches, and most preferably about 1 i nch . These parameters assi st in assuring that the compressed composite layer will provide the desi red level of lofting upon exposure to heat an~ fire.
Compressed composite 1 ayers preferably have from 35% to 98% by weight fibers based on the total wei~ht of the composite lay r, morP preferably from 40% to 80% by weigh~ thereof, and m~st preferably about 50% by weight thereof; preferably from 2% to 65% binder material based on the total weight of the 30 composite layer; more preferably from 2a% to 60% by wei ght thereof; and mos~ preferably about 50% by weight thereof. The compressed composite layer preferably has a thickness of from 0.015 inch to 0.50 inch, more preferably from 0.04 inch to 0.25 inch, and most preferably about 0.08 inch. The compressed composite layer is characterized as having a thickness of less than 50% of the original thickness of the unconsolidated web, and more preferably has a thickness of less than 25% thereof, and most preferably from 4% to 20% thereof. The compressed layer upon exposure to excessive heat or flames will loft to a lofted web thickness which is preferably a~ least double the thickness of the original compressed composite layer and which approaches the thickness of the original unconsolidated web. This lofting phenomenon all OW5 the compressed composite layer to be thin but upon exposure to fire allows the fire nesistant fiber web o~ the compressed l ayer to expand to a 1 ofted 15 thickness which will provide adequate protection tG
the underlying substrate layer. It is preferred that the fiber web of the compressed layer expands to a lofted thickness of from 0.25 inch to 3 inches upon exposure to excessive heat or flames depending upon the desired level of protection desired. The excessive heat or flames cause the binder matrix to release the compressed fibers all~wing the web to loft. The binder matrix will release the fibers when ei ther ( i ) the bi nder materi al reaches a sufficiently high temperature that its viscosity is reduced to a level low enough to allow the cumpre~sed fibers to ov~rcome the resistance of the binder material and thereby expand to a lofted thickness or (ii) the binder material is sufficiently degraded or burned to allo~ the matrix to release the fibers and allow the web to expand to a lofted thickness.
The composite layers preferably have a low level of fuel content therein to minimize the heat generated during burning of the binder matrix. Fuel ~ 12 ~
content may be minimized by employing a minimum amount of binder material in the composite. As noted above, preferably the binder material is present at a level of from 2% to 65% by weight based S on ~he ~otal weight of ~he composite layer, more preferably from 20% to 60% by weight thereof, and most preferably about 50/0 by weight thereof; in addition to minimizing fuel content in the composite layer, it is also desired to maximize the degree of lofting achie~ed by compressed composite layer upon exposure to heat and flames so that the thickness of the lofted fire resistant fiber web is maximized to thereby provide maximum protection to ~he underlying substrate. Lofting can be maximized by maximizing the fiber loading in a structure. Preferably the fiber is present in the composite layer at a concentration of from 35% to 98% by weight based on the total weight of the composite layer, more preferahly from 40/0 to 80% by weight thereof, and most preferably about 50% by weight thereof.
The composite layers may also contain from 1%
to 25% by weight mineral fillers based on the total weight of the composite layer. Suitable mineral fillers include titanium oxi~es.
Preferred structures include compressed composite layer adhered to a wooden substrate layer;
compressed composite layer adhered ~o a wooden substrate layer which is adhered to an insulative foam layer; and compressed composite layer adhered to an insulative foam layer. Other preferred structures include having a wooden substrate layer disposed between at least two compressed composite layers; and an inner uni~ having insulative foam layer disposed between at least ~wo layers of wood 08Cq!~4963 which wherein the unit is disposed between at least two compressed composi~e layers.
Another suitable structure has a unit having a foam layer disposed between a pair of wooden substrates wherein a composite layer is adhered to a surface of the unit.
Additionally, the structures may employ more than one composite layer.
The wooden substrate 1 ayers wi 11 preferably have a thickness of from 0~10 inch to 3.0 inches, more preferably from 0.20 inch to 2.0 inches, and most preferably from 0.20 inch to 1.0 inch The foam substrate layers will prefe~ably have thicknesses of from ~.25 inch to 8.0 inches.
The structures of the present invention are useful as i nteri or and exteri or bui 1 di ng materials i ncl udi ng usef ul ness as roof i ng, s i di ng, walls, f 1 oors, cei 1 i ngs, etc.
EXQMPLES
The following examples illustrate the presen~
invention but are not meant to limit the scope thereof .

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0 5 ~') ~ ~ 7 08CTû4963 An important test in the building industry involves applying a controlled flame to one side of a sheet material, for example a plywood sheet, and measuring the time that it takes ~or the temperature 5 at the back side of the sheet to reach a given temperature, for example 160C. Such tests are particularly useful when it is desired to protect certain materials such as insulative foams from temperatures in excess of 160C. Standard tests include UBC (Unified Building Code) 17-3. The following examples used a simplified test which in practice has corresponded well with thP UBC 17-3 test. The test employed in the following examples involved holding the s~ructures horizontally over a vertical flame. The structures employed were 5" X 5" square in dimensions ànd were located 4.25 inches above the base of the flame. The flame was generated using a Fischer burner and a constant methane rate throughout the tests. The composite layer was adhered to the substrate layer by phenol/formaldehyde resin glue. During testing the composite layer was located between the substrate layer and the flame. Thermocouples were placed on the back side of the substrate layer and in between the substrate layer and composite layer to measure the temperatures at those locations during the test.
The tests were conducted in a chamber to control conditions surrounding the test.
The following structures employed a 0.055 inch 30 thick compressed composite layer which was 50% by weight glass fibers having a diameter o~ 16 microns and having in general lengths of about 0.50 inch;
and which was 50% by weight of polybutylene terephthalate thermoplas~ic binder material. The compressed composite layers were produced by a ~oam dispersion process according to Gatward, et. al., U.S. Patent 3,716,449, wherein a lofted randomly oriented fiber web in the thermoplastic powder was obtained, the web was then consolidated by applying heat and pressure thereto, and was then cooled under pressure to allow the thermoplastic matrix to solidify around the fibers and hold the fibers in their compressed state. The lofted web, prior to consolidation, had a thickness of about 1 inch.
lo Various substrates were protected by the compressed composite layers and the following examples illustrate the degree of protection provided by the compressed composite layers of the present invention.

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085:~T04963 Examples 11 to 15 i 11 ustrate the degree of protecti on obtained by compressed composites employing 50% by weight polybutylene terephthalate as the binder matrix based on the total weight of the composite layer and 50% by weight glass fibers based on the total weight of the composite layer.
The glass fibers had a diameter of 16 microns. The structures employed had the 0.055 ineh thick composite layer adhered to a 0.25 inoh thick oriented strand board substrate layer. The following examples set forth the time for the backside of the structure to reach 160C after initiation of exposure of the structure to the flame. The compressed composite layer was located between the flame and the strandboard substrate layer.
Examples 16 to 20 illustrate for various glass fiber lengths the temperature between the composite layer and the substrate layer at 6 minutes after the initiation of the burn test. The structures of examples 16 to 20 are similar to the structures of examples 11 to 15.

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Claims (17)

1. A multilayered structure comprising:
(a) a compressed fiber reinforced composite layer, said composite layer having from 40% to 80% by weight glass fiber based on the total weight of said composite layer, said composite layer having from 20% to 60% by weight of a thermoplastic polymer material, said fibers being held in a compressed state by a solid matrix of said thermoplastic material, said fibers having at least 50% by weight of fiber strands having an average length of from between 0.125 inch and 1.0 inch; and (b) a substrate layer attached to said composite layer, said substrate layer being a wooden substrate layer.

2. The structure of claim 1, wherein said composite layer has a thickness of from about 0.015 inch to about 0.5 inch.

3. The structure of claim 2, wherein said composite layer is characterized by having been consolidated under pressure and heat from a unconsolidated web of said glass fibers and thermoplastic material, said unconsolidated web having had a thickness of from 0.5 inch to 5 inches.

4. The structure of claim 1, wherein at least 50%
by weight of said glass fibers have a length of from 0.125 inch and 1.0 inch.

5. The structure of claim 1, wherein said thermoplastic material is selected from the group consisting of polypropylene, polyethylene, polybutylene terephthalate, polyamide and polyethylene terephthalate.

6. The structure of claim 4, wherein said fibers have a thickness of from between 2 microns and 30 microns.

7. The structure of claim 1, wherein said substrate layer is selected from the group consisting of solid wood, plywood, particle board, flakeboard, strandboard, and oriented strand board.

8. The structure of claim 1, further comprising a solid structural insulative foam layer.

9. The structure of claim 8, wherein said foam layer is a polystyrene foam.

10. A multilayered structure comprising:
(a) a compressed fiber reinforced composite layer, said composite layer having from 35% to 98% by weight glass fiber based on the total weight of said composite layer, said composite layer having from 2% to 65%
by weight of a thermoset polymer material, said fibers being held in a compressed state by a solid matrix of said thermoset material, said fibers having at least 50%
by weight of said fiber strands having a length of from between 0.125 inch and 0.5 inch; and (b) a substrate layer attached to said composite layer, said substrate layer being a wooden substrate layer.

11. A multilayered structure comprising:
(a) a compressed fiber reinforced composite layer, said composite layer having from 40% to 80% by weight glass fiber based on the total weight of said composite layer said composite layer having from 20% to 60% by weight of a thermoplastic polymer material, said fibers being held in a compressed state by a solid matrix of said thermoplastic material, said fibers having at least 50% by weight of fiber strands having an average length of from between 0.125 inch and 1.0 inch; and (b) a substrate layer attached to said composite layer, said substrate layer being a polymeric foam substrate layer.

12. A multilayered structure comprising:
(a) a compressed fiber reinforced composite layer, said composite layer having from 35% to 98% by weight glass fiber based on the total weight of said composite layer, said composite layer having from 2% to 65%
by weight of a thermoset polymer material, said fibers being held in a compressed state by a solid matrix of said thermoset material, said fibers having at least 50%
by weight of said fiber strands having a length of from between 0.125 inch and 0.5 inch; and (b) a substrate layer attached to said composite layer, said substrate layer being a ploymeric foam substrate layer.

13. A multilayer structure comprising:
(a) a wooden substrate layer; and (b) a compressed composite layer having a thickness of from 0.015 inch to 0.5 inch, said compressed composite layer being obtained from compressing under heat an unconsolidated web of:
(i) thermoplastic binder material; and (ii) fire resistant fibers, said compressed composite layer having a thickness of less than 50% of the thickness of the unconsolidated web, said compressed composite layer having a solid matrix of said thermoplastic binder material which hold said fibers in a compressed state.

14. The structure of claim 13 wherein said composite layer upon exposure to a temperature of 400°C lofts to form a lofted web having a thickness of at least twice the thickness of said composite layer.

15. A multi layer structure comprising:
(a) a polymeric foam substrate layer; and (b) a compressed composite layer having a thickness of from 0.015 inch to 0.5 inch, said compressed composite layer being obtained from compressing under heat an unconsolidated web of:
(i) thermoplastic binder material; and (ii) fire resistant fibers, said compressed composite layer having a thickness of less than 50% of the thickness of the unconsolidated web, said compressed composite layer having a solid matrix of said thermoplastic binder material which hold said fibers in a compressed state.

16. The structure of claim 15 wherein said composite layer upon exposure to a temperature of 400°C lofts to form a lofted web having a thickness of at least twice the thickness of said composite layer.

17. The invention as defined in any of the preceding claims including any further features of novelty disclosed.