CA1264534A

CA1264534A - Nonwoven fibrous insulation material

Info

Publication number: CA1264534A
Application number: CA000505844A
Authority: CA
Inventors: Michael C. Jaskowski
Original assignee: Usg Acoustical Products Co
Current assignee: Usg Acoustical Products Co
Priority date: 1985-04-08
Filing date: 1986-04-04
Publication date: 1990-01-23
Anticipated expiration: 2007-01-23
Also published as: US4847140A

Abstract

A nonwoven composite fibrous material adaptable as an insulation medium is formed by a loose layer of inorganic fibers, such as rock wool, glass, ceramic, carbon-graphite or the like, bonded together by at least one carrier web layer positioned on a surface of the inorganic fibrous layer. The carrier web layer is a blend of inorganic fibers and organic fibers with the organic fibers comprising about 1% or less by might of the total nonwoven composite fibrous material. Both organic and inorganic fibers of the carrier web are advanced into interlocking relation with the fibers of the inorganic layer by needle punching the carrier web. The carrier web organic and inorganic fibers have a length greater than the thickness of the inorganic layer in the composite fibrous material so that the needle punching advances organic and inorganic fibers from the carrier web completely through the inorganic layer to mechan-ically bind together the fibers of the inorganic layer to resist separation of the fibers and delamination of the inorganic layer upon handling and instal-lation.

Description

.. .. ~ ~ ' .
HELhIIC
6737 1~~4 lls TITLE
NONWOVEN FIBKOUS INSULATION MATERIAL
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to a nonwoven fibrous material and, more particularly, to a nonwoven composite insulation material that includes a layer!
of inorganic fibers bonded together by a carrier web of blended organic and inorganic fibers.

2. Description of the Prior Art It is well known in the art of thermal and sound insulation to bond together glass fibers in nonwoven, felt-like layers by a resinous binder. The binder, may be of either the thermosetting or the thermoplastic type. Examples of this type of insulation material are disclosed in United States Patents 2,579,035; 2,598,102; 2,612,162; 2,633,433; and 3,144,376. Mineral Col, also identified as rock wool, slag wool, or mineral cotton is a loose fibrous mate-rial also known for thermal and sound insulation properties. In addition, mineral wool is used to fabricate synthetic resin-bonded panels for speci-fic structural purposes and has application as a filtering medium and a fire-proofing material.
Mineral wool is an inorganic material in the form of a mass of finely intertwined fibers formed by blowing, air or steam through ~i'olten rock or slag.
A three-dimensional layer of intertwined mineral wool fibers lacks struc-tural integrity since the fibers, even though intertwined, are brittle. Thus, without treatment, a layer of mineral wool fibers lacks structural strength for handling and installation as an insulator, a filter medium, a fireproofing if c ~.2s4s3~
material, etc. To overcome this deficiency, the fibers of a layer of minera:
wool must be bonded together so as to resist splitting and delamination of the material when placed in use. Furthermore, because mineral wool is substam tially a coarse and abrasive material, special handling procedures are require to permit efficiency in fabrication and use.
It is a known practice to bond together the fibers of a mineral wool layer by the use of resin, as is generally disclosed in U. S. Patent No.

3,778,334. A thermosetting resin is-applied to mineral wool fibers as they are spun to form a mass of intertwined mineral wool fibers. Zhe resin binds the individual fibers together to prevent delamination of the layer. The resin is generally applied in the form of an aqueous solution, such as a water insoluble thermosetting resin in liquid form, an aqueous dispersion of a water insoluble thermosetting resin, or in a dry, powdered finely divided form.
The use of thermosetting resins as binders for mineral wool, or fo.
any fibrous material in general, to form a nonwoven fibrous structure is ob-jectionable because of the health hazard presented during the application of the resin to the fibrous layer. It is.a common practice to disperse the resin in both a powder and liquid spray form which causes the resin to circulate into the air presenting an unhealthy working environment. Also, resin in liquid form must be carefully handled so as to prevent contamination of a public water system. For these reasons it is preferred to avoid the use of a resinous binder to form nonwoven insulation materials from inorganic fibers, such as rock wool.

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x.264534 Various alternatives to resin bonding of inorganic fibers to form , nonwoven, felt-like material are disclosed in United States Patents 2,908,064 3,317,335; 3,338.777; 3,608,166; 3,616,031; 3,917,448; 3,975,565; 4,081,582 and 4,237,180. United States Patent 3,917,448 discloses forming a nonwove material including a percentage of heat-shrinkable synthetic fibers blended wit non-shrinkable fibers into a web in which both the shrinkable and non-shrinkabl fibers are randomly arranged in three dimensions. These fibers are so entangled that when exposed to heat treatment the shrinkable fibers contract to mechani-Ically interlock the shrinkable and non-shrinkable fibers and provide the ~~with a preselected thickness and density.
Similarly, United States Patent 4,237,180 discloses an insulation material formed by a blend of organic and inorganic fibers processed by carding or garnetting to form a composite insulating fibrous material of a preselected thickness. About two to ten percent by weight of heat sensitive organic fibers, Ilsuch as polyester fibers, are oriented within the composite material by needling process to interlock with the inorganic fibers and compress i composite material to the preseleted thickness. The interlocking arrangement organic and inorganic fibers are subjected to a shrinking treatment in which organic fibers contract and bind the inorganic fibers together to form a oom site insulating material having a tensile strength sufficient to prevent spli ing and delamination of the composite body. However, an essential step in formation of these types of nonwoven fibrous insulation materials is h treating the blend of organic and inorganic fibers to shrink the organic fiber so as to bond together the inorganic fibers.

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x.264534 On the other hand, United States Patent 4,081,582 employs a similia~
quantity of organic fibers which are fused by preheating to provide bondin~
for the overall fibrous material disclosed therein. United States Paten 3,601,081, discloses the bonding of felt-like materials where organic fibers are ~~added and then heated and cooled to provide the required bonding.
Several prior art patents disclose c.,omposite nonwoven insulation materials formed by superimposing or layering in a preselected orientation loos batts of fibers. Zhe layered batts are sent through a needle loom, such a.
disclosed in United States Patent 2,958,113, that includes a pair of vert ~Ireciprocating needle boards containing an array of barbed needles. With loose layers stationarily positioned between the boards, the boards are recipro-Gated so that the needles penetrate the layers. In this manner, the fibers of the outer layers are advanced downwardly and upwardly in the direction of the movement of the needles toward the center layer to entangle the fibers of the ~~various layers and thereby mechanically interlock the layers. The size and number of needles on the board, as well as the number of punching operations per square inch of the layered material, determine the density and thickness of composite material.
For example, the nonwoven material formed by ttue process disclosed United States Patent 2,908,064 includes loose batts of synthetic organic fibrou material which, after needle punching, can also be heated to a suitable tempera ture to retract the fibers and increase the overall density of the composi material. Meanwhile, United States Patent 3,317,335 employs a large quanti of organic fibers which are needle punched into a mat and then heat I~to insure proper bonding. Although employing a primary mat of glass fiber

- 4 -_II c lzs4s34 which are "connected" by needle punched organic fibers, United States Paten 3,608,166 teaches preheating the organic fibers and adding a coating to glass fibers to facilitate the needling.
Lastly, United States Patent 3,975,565 discloses a fibrous structur~
Ilthat includes a plurality of interlayered inorganic fiber mats and organic fibe webs which are held together by needle punching the organic fibers from the outer web into the inorganic mat. The multi-layers are needle punched from both the top and the bottom. As a result the layers are mechanically interlocked.
The preferred arrangement is to sandwich the inorganic fiber mat between organic Ilfi~r webs. The organic fiber webs are. preferably fabricated of natural synthetic fibers, for example nylon or polyester. It is further disclosed the inorganic fiber mat can include mats of glass fibers, mineral and clay fibers, alumino-silicate fibers, silica fibers, and polycrystalline fibers, as zirconia or alumina.
II The above-mentioned prior art patents disclose various methods employing organic fibers to form organic and inorganic fiber insulation n which may be sufficiently strong and flexible to facilitate handling prior installation. However, it should be recognized that organic fibers are subj to disintegration when exposed to elevated temperatures. In fact, for some hi Iltemperature applications, it appears that the composite insulation mater taught hereinabove ~rould contain too high a concentration of organic fibers.
a result, destruction of the organic fibers could sufficiently reduce mechanical strength and integrity of the insulation material to make it unsa factory for such use.

~If Although United States Patent 3,338,777 discloses a fibrous ma which, in one embodiment, includes no organic binder, the inorganic strands mus linitially be crimped and relatively moved with respect to one another in all directions to insure adequate distortion. Assuming such strands could be ~~obtained, they would appear relatively expensive to provide. In any case, (crimped inorganic strands would then be sent to a cutter machine, a garnet machine, a lapping machine, and a needle loom. Although the completed ilmaterial might be sufficiently strong and capable of withstanding higher (temperatures, there is no disclosure of the resulting flexibility which can Ilimportant during handling and installation and has heretofore been made poss ~by the inclusion of organic fibers within the mats.
Therefore, there is a need in the formation of nonwoven insulati materials containing primary inorganic fibrous material, such as glass fiber and rock wool, to utilize a minimum amount of organic fibers for bonding Ilher the inorganic fibers in an initial form to provide the desired mechanica strength and flexibility needed for handling prior to and during installation.
However, the amount of organic fibers present should be such that, if the organic fibers are exposed to elevated temperatures after installation, their disintegration will not materially affect the mechanical strength and integrity ~~ of the composite insulating material.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a composite fibrous material that includes a layer of inorganic fibrous materi containing fibers in an unbonded state. A carrier web is positioned on t Illayer of inorganic fibrous material. The carrier web includes an admixture -6.

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~.2s~s~4 inorganic and organic fibers. The inorganic and organic fibers are blended in nonwoven structure to provide the carrier web with a preselected thickness an density with the organic fibers of the carrier web preferably comprising abou 1$ or less by weight of the composite fibrous material. The carrier web i needle punched to the layer of inorganic fibrous material to interlock th carrier web inorganic and organic fibers with the fibers of the inorgan fibrous material layer so as to bond together the fibers of the inorgan fibrous material and form the cohesive, nonwoven composite fibrous materi having a mechanical strength and flexibility to resist separation of the fibs of the layer of inorganic fibrous material upon handling.
Further, in accordance with the present invention, there is provided , nonwoven composite insulation material that includes a layer of mineral woo fibers. The layer has a preselected thickness. The fibers of the layer are i;
an unbonded state. A carrier web is provided for binding together the minera wool fibers. The carrier web includes an admixture of inorganic and organi~
fibers. The inorganic fibers preferably comprise at least about 90$ by weig of the carrier web. The inorganic and organic fibers are blended to form nonwoven structure. The carrier web is positioned in contact with the layer mineral wool fibers. The carrier web is needle punched to the layer of miner wool fibers to interlock the carrier web inorganic and organic fibers with t mineral wool fibers so as to bond together the mineral wool fibers and form cohesive, nonwoven composite insulation material.
The present invention is also directed to a process for making nonwoven fibrous material that includes the steps of blending inorganic fibrc material in a concentration by weight of at least'about 90~ with organic fibr<

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material to form a composite nonwoven carrier web having a preselected thicknes and density. The carrier web is positioned in overlying relation with a laye of mineral wool fibers. The layer comprises an unstructured concentration o mineral wool fibers of a preselected thickness and density. The carrier web i needle punched to advance the inorganic and organic fibrous material int contact with the mineral wool fibers. The layer of mineral wool fibers is contracted by the interlocking relation of the inorganic and organic fibrous material with the mineral wool fibers to bond together the mineral wool fibers to form a structured composite, nonwoven fibrous material having a preselected thickness and density.
Accordingly, the principal object of the present invention is t provide a nonwoven fibrous insulation material that includes a layer of inor ganic fibers bound together by needle punching a carrier web containing a blen of inorganic and organic fibers into interlocking relation with the laye of inorganic fibers to form a composite structure having mechanical strength an flexibility to permit handling without delamination of the layer of inorgani fibers.
Another object of the present invention is to provide a mineral wo insulating blanket that includes at least one carrier web positioned in ove lying relation with a layer of mineral wool fibers and needle punched into t mineral wool fibers to provide the insulation blanket with mechanical streng and flexibility for use in thermal and sound insulating applications.
A further object of the present invention is to provide a proces for making a nonwoven fibrous material by mechanically interlocking the indi vidual fibers of an inorganic batt, such as a glass fiber batt or a rock woo _ g _ C
12f 4534 fiber batt, with a carrier web containing a blend of organic and inorgan fibers so as to provide a composite nonwoven material for application as linsulating medium.
These and other objects of the present invention will be more Ilpletely disclosed and described in the following specification, the accanpany drawings, and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross sectional view in side elevation of one example a nonwoven fibrous insulation material, illustrating a layer of inorganic fiber Ilbonded together by needle punching organic and inorganic fibers from top bottom carrier webs into the inorganic fiber layer.
Figure 2 is a view similar to Figure 1, illustrating another of an insulation material formed by needle punching fibers from a top carr web through a layer of inorganic fibers into locking engagement with a bot Ilscrim.
Figure 3 is a cross sectional view illustrating another embodimen of a nonwoven fibrous insulation material formed by bonding together layers of inorganic material separated by a center carrier web in which fiber from upper and lower carrier webs pass through the inorganic layers int ~~engagement with the center carrier web.
Figure 4 is a view similar to Figure 1 of another embodiment, trating top and bottom carrier webs needle punched to an inorganic layer by a lamination of different types of inorganic fibers.

c Referring to the drawings and particularly to Figure 1, there illustrated a nonwoven composite fibrous material generally designated by numeral 10 that includes a primary layer or batt 12 of inorganic fibrous ~~ial containing fibers 14 selected from a group that could include mineral wool, glass wool, glass fibers, metal oxide fibers, graphite or carbon fibers, ceram fibers and the like. The layer 12 of inorganic fibrous material has a pr selected thickness and density applicable for a specific use as an insulati material, a filtering medium, a fireproofing material, and for other structur ~~PurPoses. It v~uld not be uncanmUn for the initial thickness to be within range of four to eight inches.
The fibrous inorganic layer 12 is a nonwoven structure or a loose which is initially formed in an unbonded state, i.e. the inorganic fiber 14 are not initially interlocked. Without further treatment the loose ~~lacks the mechanical strength to resist separation of the fibers and ination of the batt upon handling.
however, in the preferred material 10, the loose batt 12 of inorganic fibers 14 is bound together by one or more carrier webs 16 and 18 which are dle punched to the batt 12, as illustrated in Figure 1. Each carries web 16 and 18 includes a preselected blend of organic fibers 20 and inorganic fibers 21. The organic fibers 20 and inorganic fibers 21 are blended in lected ratio by weight to form an admixture which is conveyed to a garnet ng or carding machine, in a manner which will be discussed in detail hereim low, where the fibers are interlaced to form a continuous nonwoven web havinc ~~a preselected thickness and density. Preferably, the carrier webs 16 and 11 -in-_II <
~,2f 4534 formed in this manner contain at least about 90~ by weight inorganic fibers 2 and up to about 10$ by weight organic fibers 20. The webs 16 and 18 woul preferably combine to contribute a total of about 5$ to as much as 10$ by weigh to the entire composite fiber material 10. Consequently, the layer 12 0 inorganic fibers 14 could contribute 90$ to 95$ or more to the overall weight o the composite fibrous material 10.
The organic fibers 20 are preferably selected from the group consis-ting of vinylidene chloride fibers, polyolefin fibers, polystyrene fibers, copolymer polystyrene fibers, acrylonitrile fibers, polyamide fibers, poly-vinylchloride fibers, polyester fibers, acetate fibers, and other thermoplastic fibers. The inorganic fibers 21 forming the carrier webs 16 and 18 are pref-erably selected from a group consisting of glass fibers, metal oxide fibers, carbon-graphite fibers and ceramic fibers. The fibers 20 and 21 of the webs 16 and 18 include a substantial portion which preferably have a length which i~
greater than the eventual compressed thickness of the resultant composite material 10.
It has generally been accepted, if there is a sufficient quanti of each, that the inorganic and organic fibers can be blended in a convention manner, as by carding, garnetting and the like, to form a nonwoven carrier w of a preselected thickness and density. Prior to such blending the organic a inorganic fibers 20 and 21 would each be in batch form, but the individua fibers should be separated by suitable means to facilitate uniform blending i an admixture. In one such method, the given quantity of organic fibers 20 ar distributed onto a conveyor and advanced through a garnett machine which sepa rates the fibers to filament form. The inorganic fibers 21 are also similarl C
1~~.~~4 fibers are available for blending. However, it has been found that the organic and inorganic fibers 20 and 21 could only be blended in this conventional manner in a preselected percentage by weight which is significantly different fran th<
proposed percentage of the present invention. Specifically, the surfaces of the untreated inorganic fibers do not have a sufficiently high coefficient of friction to insure a proper blend. Further, it has been found that static electricity can cause the fibers to~resist such a carding or blending process In accordance with the present invention the organic and inorganic fibers 20 and 21 of each carrier web are blended in a preferred preselecte~
ratio to provide the carrier web with heat resistivity as well as strength any flexibility. This can be accomplished by blending the fibers 20 and 21 to fon an admixture as shown in Figure 1 to provide each carrier web 16 and 18 in three-dimensional felt-like layer in which a lesser quantity of organic fiber.
are evenly distributed throughout the inorganic fibers 21. The organi~
15 fibers 20 and inorganic fibers 21 should be randomly arranged in the respective carrier webs 16 and 18. However, the fibers 20 and 21 should be blended in the preselected percentage by weight so that the formed carrier web includes at least 90$ to 99$ by weight inorganic fibers 21 with a selected percentage by weight of organic fibers 20, for example 1$ to 10$.
20 With this preferred ratio of inorganic fibers 21 to organic fibers 20, each carrier web 16 and 18 has a degree of thermal resistivity not with-standing the presence of such a small quantity of~organic fibers.
Consequently, when the carrier web 16 and 18 is exposed to elevated temperatures, for example in the range of 1,300°F, the structural integrity of the carrier web 16 and 18, and, more significantly, the entire material 10, is not lost by disintegration of the organic fibers.

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However, the presence of the preferred quantity of organic fibers lin each carrier web 16 and 18 has been found to be sufficient to init provide the respective carrier web with the strength and flexibility needed handling and installation of the composite fibrous material 10. The Ilfibers 20 function in a composite insulation material 10 having a rock layer 12, for example, to prevent splitting or delamination of the rock sx~o layer 12 during installation as a thermal insulator. on the other hand, afte installation, such flexibility is no longer a requirement and loss of som of the organic fibers 20 upon exposure to elevated temperatures can occur at th Ilarea of contact with the heat source without affecting the insulation properti of the composite fibrous material 10. Nevertheless, it is the presence of organic fibrous material in the carrier web which primarily provides the site fibrous material 10 with the properties of mechanical strength and ibility needed for handling prior to and during installation.
II Accordingly, minimizing the content of the organic fibrous material the carrier web 16 and 18, and the entire composite material 10 is preferred particularly for high temperature applications. If the carrier web were pr dcxninantly or entirely organic material, then the entire carrier web would substantially destroyed in such high temperature applications. This Ilresult in a breakdown in the structural integrity of the inorganic fi ',layer, for example rock wool, and an overall failure of the composite insulat material. Therefore, by providing a carrier web 16 and 18 having no more about 10$ by weight organic fibrous material and the entire material 10 with n more than about 1$ by weight organic fibrous material, the properties o Ilflexibility and strength are initially present and the thermal resistivity o the carrier web is not lost in high temperature applications.

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12f 4534 Et~en though some of the organic fiber content may be destroyed afte the composite insulation material 10 is installed and subjected to elevate temperatures, the integrity of the carrier web 16 and 18 in the composit fibrous material 10 will be maintained because of the presence of at least 90 by weight inorganic fiber content. Thus, the preferred content of the organi fibrous material in the carrier web is not an amount which when exposed t~
elevated temperatures and consumed results in the destruction of the carries web. However, it is the organic fiber content of the carrier web which initial ly enhances the flexibility and mechanical strength of the composite fibrou - 10 material.
In order to be capable of providing the desired webs 16, 18, i is appropriate to discuss a specific composition of inorganic glass fiber and organic polyester fibers. It has been found that the blending and cardin of an admixture of glass and polyester fibers can be enhanced by a preferre pretreatment process which appears necessary due to the surface characteristic and regity in straightness of the glass fibers. It is known that glass fibs may not be conducive to a carding process in which the fibers are separated form a cohesive web structure. Unless otherwise treated, glass fibers by the nature are not crimped or curled. Therefore, it is necessary to increase t frictional characteristics of the surface of the glass fibers. This is a cvmplished in the preferred process by causing the glass fibers to be coat with a friction enhancing substance, such as a starch or silica gel. T, friction enhancing substance can be applied during the process of fabricate;
the glass filaments when they are extruded and prior to cutting the fibers in desired staple lengths. On the other hand, because most organic fibers a available in crimped forms and have noncircular cross sections, they do n require an application of any friction enhancing substance.

~II ~ r 1,264534 It has also been found that, in addition to increasing the frictiona properties of the glass fibers,, it is important to neutralize the effects o static electricity applied to the glass fibers and the organic fibers during th carding process. If an electro-static charge is applied to the glass fiber and/or the organic polyester fibers, they may repel each other and resist th carding and blending process. Zb overcome the problem of static electricity the fibers can be sprayed with an anti-static agent, such as water . Sprayin~
the fibers with water increases the humidity of the ambient air. For example the surrounding air could have a humidity of about 6U~ and, as a result the static charge can rapidly dissipate before the blending and carding proces to form the web formation.
It should be also understood that for optimum carding and blending the organic and inorganic fibers, the fiber diameters are preferably ma tained within a preselected range, such as 5-50 microns. Most prefera extreme differences in diameters between the organic and inorganic fiber she be avoided, such as, for example, 5-50 microns for one fiber and 50-100 mice for the other fiber. Fiber diameters of this differential could result "clump-formation" of the "finer" fibers and in a non-homogeneous web. For needling process, the fiber diameters must be of such dimension as to fit the barb gap of the needles. A typical needle configuration could pros 50 needle penetrations per square inch of batt surface. Of course, the bat may be run through the needle area a selected number of times, for example,.
times per face of the batt for a total of 16 passes. Thus, it is preferred the the glass and organic fibers be pretreated prior to the blending process so to avoid an uneven web formation having large clumps of partially separate glass fibers.

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With the carrier webs 16 and 18 preferably processed in the manner described, the layer 12 of inorganic fibrous material shown in Figure 1 i:
(provided structural strength by needle punching the preferred carrier webs land 18 to a top surface 22 and a bottom surface 24 of the layer 12.
Preferably Ilas mentioned hereinabove, the inorganic fibrous material 12 is selected from the group consisting of mineral wool, glass wool, glass fibers, metal oxide fibers ceramic fibers, graphite and carbon fibers and the like. The inorganic fiber.
may be formed to have a preselected- diameter and cut to a preselected length.
For example, a batt 12 of rock we~ol fibers can be formed having fiber lengths of ~~one-half to three-fourth inches where the fibers have an average diameter in range of about 5 to 8 microns with individual fiber diameters ranging from 0.
to 30 microns.
In one method of the formation of a fiber batt 12, rock wool fibers fed to a garnett or carding machine to separate the fibers in filament R after they have been cut to the desired length. Carding or garnetting rock wool fibers forms the three-dimensional felt-like batt 12, as shown Figure 1, which has the substantially planar top and bottom surfaces 22 and 24.
Prior to needling, the batt 12 has a preselected thickness, for example, about E
inches.
II The formed batt of inorganic fibrous material is then combined wi the carrier webs 16 and 18 by the needle punching operation. The carrier is fed from a roll onto at least a selected one of the top and bottom surtac 22 and 24 of the inorganic fibrous batt 12. In one method the carrier web fed from a pair of rolls positioned above and below the inorganic batt. Wi Ilthis arrangement, as shown in Figure 1, the inorganic fibrous batt 12 is sand wicked between the top carrier web 16 and the bottom carrier web 18.

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~Jith the webs 16 and 18 positioned in contact with the top and bottom surfaces 22 and 24 of the inorganic fibrous batt 12, both are needle punched to advance both the organic fibers 20 and inorganic fibers 21 from the webs 16, perpendicularly through the inorganic fibrous batt 12. Preferably the fibers 20, 21 from the top carrier web 16 are advanced through the batt 12 into the bottom carrier web 18. Similarly, the fibers 20, 21 from the bottom carrier web 18 are advanced through the batt 12 into the top carrier web 16. For this reason the carrier web fibers 20, 21 preferably have a length greater than the thickness of the batt l2 for the resultant composite material 10.
In another embodiment, a composite fibrous material 25. shown in Figure 2, utilizes only a single carrier web 16 positioned on one surface 22 of the inorganic fibrous batt 12. For example, the formed carrier web 16 is advanced or laid into overlying relation on the top surface 22 of the batt 12.
When only a single layer of carrier web is utilized, it is preferred that a thin scrim 26 of either woven or nonwoven mesh material is fed into contact with opposite surface 24 of the batt 12. If the carrier web 16 is positioned on top surface 22 of the batt 12, then the scrim 26 is positioned in underly relation with the batt 12.
The layered arrangement'of the carrier web (one or more layers) the inorganic batt as shown in Figures 1 and 2 is advanced through a needle 1 or a needle felter. A needle loom, as is well known in the art, is a dri reciprocating machine that includes at least one needle board filled with bar needles. The composite arrangement of materials is horizontally fed under _II <
1,264534 vertically oscillating needle board. In one method of operation a pair o needle boards are used for the arrangement shown in Figure 1. The needle board are vertically reciprocated so that barbed needles simultaneously penetrate th top and bottom carrier webs 16, 18, driving the fibers 20, 21 into engage ment with the inorganic fibers 14 to bind them together. In the alternative the composite material 25 may be needled from only one side, as shown in Figure 2. Only the top carrier web 16 is needled with the scrim 26 on the opposite side not being needled. However, as with the embodiment shown in Figure 1 the fibers 20, 21 of the web. 16 should be advanced through the batt 12 into the scrim 26.
The barbed needles penetrate the horizontal surfaces of the composit material 10 to perpendicularly align a substantial number of the organi fibers 20 and inorganic fibers 21 from the respective carrier webs 16 and 1 with the batt 12 of inorganic fibrous material. With this process, the compc site fibrous material 10 is formed for thermal and/or sound insulation applica tions with the required properties of mechanical strength and flexibility of tY
composite material. The loose fibers 14 of the inorganic batt 12 are interlocks or mechanically bonded to one another by the fibers 20 and 21 from the t~
carrier webs 16 and 18 with the arrangement shown in Figure 1 or from the sing?
carrier web 16' shown in Figure 2. Treating the composite material 10 in th:
manner provides the inorganic fibers 14 of the batt 12 with sufficient mechac ical strength to permit handling and installation without splitting or delamic ~II

ation of the inorganic fibrous batt 12. The size of the needles, number type of barbs, the number of needles, the number of punches per unit area, the length of penetration of the needles are all controlled during the need) operation to give the composite fibrous material 10, 25 the desired mechani strength and flexibility.
Prior to the needling operation, the combined layers of the batt 12 and the carrier webs 16 and 18 have a preselected thickness, for example) slightly more than approximately 8 inches. Preferably, before the composite material layers of the carrier webs 16 and 18 and inorganic batt l2 are passed through the needle looqn, the layers are compressed by rollers to reduce the i total thickness Qf the composite structure 10 from a thickness of about 8 inches) to approximately 4 inches. The composite material is then conveyed through the i needle loom to form a resultant nonwoven composite fibrous material 10 ins;
accordance with the present invention having a thickness of about 1 to 2 inches.;
. Referring to Figure 3, there is illustrated another embodiment of a' nonwoven composite fibrous material 28 in which corresponding elements are) identified by the same numbers used in Figure 1. The fibrous material 28 includes the inorganic batt 12 of fibers 14 connected by needle punching to top and bottom carrier webs 16 and 18 containing a blend of organic fibers 20 and inorganic fibers 21 in the arrangement described above for the fibrous material 10 shown in Figure 1. This structure is then combined with another composite structure formed by a second inorganic batt 30 which is connected to the carrier web 18 and a lowermost carrier web 32 by needle punching as above described.
The inorganic batt 30 shown in Figure 3 is formed of inorganic fibers 34 sel-ected from the same group of inorganic fibers 14 used in the batt 12. The ~II <

inorganic fibers 14 and 34 may be the same material or different materials. F.
example, the fibers 14 could be rock wool fibers while the fibers 34 could I
ceramic, glass, or carbon-graphite fibers. Thus, the inorganic fibers for t batts 12 and 30 can be selected to meet specific requirements for the specif application of the composite fibrous material 28.
For use as a thermal insulating material capable of withstandinc temperatures of up to 1,300°F, the batt 30 can be fabricated of ceramic fiber.
34 with the batt 30 being separated from the heat source by the carrier web 32 The carrier web 32 would also be formed of a blend of organic fibers 36 an.
ingoranic fibers 37 containing at least about 90~ by weight inorganic fibers any up to about 10~ by weight organic fibers.
With the arrangement shown in Figure 3 the carrier webs 16 and are needle punched to the inorganic batt 12 in the manner described for arrangement shown in Figure 1. The batt 30 would include a top surface abutting the carrier web 18 and a bottom surface 40 abutting the carrier 32. By needle punching the carrier web 32 to the batt 30, fibers 36 and 37 frog the carrier web 32 are advanced upwardly through the batt 30 and into engagemen with the fibers 20 and 21 of the carrier web 18. The fibers 36 and 37 of th carrier web 32 have a length which is greater than the thickness of the batt 3 in the composite fibrous material 28. This assures binding together of th inorganic fibers 34 of the batt 30. Thus, the composite fibrous material 28 i formed by the inter-locked relation of the carrier webs 16, 18 and 32 and th inorganic batts 12 and 30.

_II ~ r A modification of the composite fibrous material 28 of Figure 3 i shown in Figure 4 in which a composite fibrous material 42 includes the top an bottom carrier webs 16 and 18 of blended organic fibers 20 and inorganic fiber 21 as above described for Figure 1. Positioned between the carrier webs l6 an 18 is a composite inorganic batt generally designated by the numeral 44. Th batt 44 is formed by a plurality of stacked layers of different types of inor ganic fibrous material. Two layers 46 and 48 are illustrated in Figure although additional layers can be utilized.
The first inorganic layer 46 is formed of preselected inorg fibers 50, such as rock wool fibers, and the second layer 48 is formed of other inorganic fibers 52, such as ceramic, carbon-graphite, metal oxide, and the like. Initially, the tvx~ inorganic layers 46 and 48 are stacked together and the carrier webs ~16 and 18 are positioned in overlying and undeflying relation with the layers 46 and 48 for needle punching of the composite material 44.
Both carrier webs 16 and 18 are needle punched to advance the fibers 20 and 21 thereof through the layers 46 and 48. Accordingly, the length of the fibers 20 and 21 is selected to insure that they extend completely through both layers and 48. This arrangement allows one to utilize different characteristics of different types of inorganic fibers 50 and 52 in a batt 44, where, for example, one layer would have a higher resistance to temperature than the other layer.
The following examples are illustrative of the nonwoven composi fibrous material of the present invention:

.II ~ r 126~5:~4 The canposite fibrous material has a three-dimensional felt-li structure that includes an inorganic fibrous material layer of mineral comprising 95$ by weight of the composite fibrous material. A top carrier Illayer comprises 2.5$ by weight of the composite fibrous material, and a carrier web layer comprises 2.5~ by weight of the composite fibrous material.
Thus both the carrier webs together comprise 5$ by weight of the composi fibrous material.
The composite fibrous material has a thickness of about 2 inches and Ilweight of 1.67 lbs. per sq. ft. The mineral wool layer has a weight of 1.58 lbs. per sq. ft. The top and bottom carrier web layers have a combined weigh of 0.083 lbs. per sq. ft.
The top"and bottom carrier web layers each include a nonwoven of inorganic and organic fibers. Z'he inorganic fibers are glass fibers Ila length in excess of two inches. The organic fibers are polyester fiber (having a length in excess of two inches. The glass fibers constitute 90$
weight of each carrier web layer, and the polyester fibers constitute 10$
weight of each carrier web layer.
Each carrier web layer has a weight of 0.042 lbs. per sq. ft.
Ilw~eight of the glass fibers of each layer is 0.038 lbs. per sq. ft. and weight of the polyester fibers of each layer is 0.004 lbs. per sq. ft.
carrier webs are initially prepared by blending and carding an admixture glass and polyester fibers which are pretreated to increase the frictic characteristics of the glass fibers and to eliminate the problem of sta Ilelectricity, as mentioned hereinabove, to facilitate the blending and carding obtain the desired ratio of 90~ by weight glass fibers to 10$ by weight pvl fester fibers for each carrier web.

:II <
~.2s~34 Initially, the three-dimensional layer of mineral wool fibers incl fibers which are unbonded in a loose layer of about 8 inches thick and Itop and bottom surfaces. The carrier webs are fed into overlying and underly relationship with the layer of mineral wool fibers to form a composite str ~~ture. The composite structure is compressed by rollers to a thickness of ~4 inches and is fed through a needle loom that includes upper and lower boards equipped with a preselected array of barbed needles.
The needle boards are oscillated at a controlled rate in timed ~tion with the horizontal feed of the composite material to move the Ilneedles into and out of the material and thereby advance the inorganic organic fibers of the carrier webs into mechanical interengagement with t.
mineral wool fibers. The mineral wool fibers of the material layer are th bonded together lay the polyester and glass fibers of the carrier web. In th manner a resultant nonwoven composite fibrous material is formed having Ildesired thickness of about 2 inches and a density of about 1.67 lbs. per sq.
ft. The composite fibrous material has a felt-like texture on the top bottom surfaces and is flexible to the degree to permit handling and instal lation as both a thermal and sound insulator without experiencing delaminat or splitting of the mineral wool fibers.

A nonwoven composite fibrous material is formed as substantial described in Example 1 in which the inorganic fibrous material is a layer mineral wool constituting 90~ by weight of the entire composite fibrous rial. Rather than utilize upper and lower carrier web layers in a I~arrangement, a single carrier web layer is positioned on top of, the mineral layer. The single carrier web layer constitutes 10~ by weight of the composi fibrous material.

~If r 1.2f 4534 The mineral wool layer has a weight of 1.503 lbs. per sq. ft., anc (the single carrier web layer has a weight of 0.167 lbs. per sq. ft. The singlE
carrier web layer is a nonwoven blend of inorganic and organic fibers in (the inorganic fibers are ceramic fibers and the organic fibers are polyester Ilfibers. These inorganic and organic fibers are blended in different percentages Iby weight than the carrier webs described in Example 1 with there now being 9 Iby weight inorganic fibers to 5~ by weight organic fibers.
The single carrier web layer is fed into overlying relation with the (top surface of the mineral wool layer. A thin scrim of woven glass fiber is Ilinto underlying relation with the mineral Col layer to support the,layer dur (the needling operation. Zhe composite material is compressed from an 8 thickness to a 4 inch thickness and then fed through a needle loom. fbwever, rather than usinj a pair of needle boards as described in Example 1, only a (single needle board is used to advance the fibers of the carrier web Ilinto engagement with the scrim to form an interlocking relation with th nineral wool fibers to bind together the mineral wool fibers. The resul composite nonwoven fibrous material foimed in this manner has a thickness o about 2 inches and density of about 1.67 lbs. per sq. ft.

~~ A nonwoven composite fibrous material includes the arrangement de cribed .in Example 1 where a layer of loose mineral wool fibers is posit between top and bottom carrier web layers. The carrier web layers inc inorganic and organic fibers blended in the same ratio as above descr iw Example 1 with the exception that, instead of glass fibers, the inorg Ilfibers of the carrier web are quartz fibers. The density ratios of miner .II
1~~4534 wool fibers and the carrier webs are the same as described in Example 1.
top and bottom carrier web layers are needle punched into mechanical inter gagement with the mineral wool layer to form a nonwoven composite fibr material having a thickness of 2 inches and a density of 1.67 lbs. per sq II ft.

A nonwoven composite fibrous material is formed in accordance wi Example 1 with the exception .that instead of using a single layer of miner wool fibers for the inorganic batt, a layer of glass fibers is stacked on Illayer of carbon-graphite fibers to form a composite inorganic batt. The of glass and carbon-graphite fibers are mechanically interlocked with the fi of the top and ..bottom carrier web layers by the needle punching opera described in Example 1. The nonwoven composite fibrous material thus formed the same general thickness and density as described for the composite ~~material described in Example 1.
According to the provisions-of the patent statutes, I have expla the principle, preferred construction and mode of operation of my invention and have illustrated and described what I now consider to represent its bes embodiments. However, it should be understood that, within the scope of ~~ aPPended claims, the invention may be practiced otherwise than as specif illustrated and described.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A nonwoven composite fibrous material comprising:
a discrete layer consisting essentially of inorganic fibrous material containing fibers in an unbonded state;
at least one discrete nonwoven carrier web positioned on a surface of said discrete layer of said inorganic fibrous material;
said discrete nonwoven carrier web including an admixture of inorganic fibers and organic fibers;
said inorganic fibers and said organic fibers of said nonwoven discrete carrier web being blended in a nonwoven structure with a preselected thickness and density with said organic fibers of said discrete carrier web comprising about 1% or less by weight of said composite fibrous material; and said nonwoven discrete carrier web being needle punched to said discrete layer of said inorganic fibrous material to interlock said inorganic fibers and said organic fibers of said carrier web with said fibers of said layer of inorganic fibrous material so as to bond together said fibers of said inorganic fibrous material and form said nonwoven composite fibrous material which is cohesive and has a mechanical strength and flexibility to resist separation of said fibers of said layer of said inorganic fibrous material upon handling.

2. A nonwoven composite fibrous material as set forth in claim 1, wherein said inorganic fibers comprise at least about 90% by weight of said carrier web and said organic fibers comprise up to about 10% by weight of said carrier web.

3. A nonwoven composite fibrous material as set forth in claim 1, further including a first discrete carrier web positioned in contact with a top surface of said layer of said inorganic fibrous material, a second discrete carrier web positioned in contact with a bottom surface of said discrete layer of said inorganic fibrous material, said first carrier web comprises about 2.5% by weight of said composite fibrous material, said second carrier web comprises about 2.5% by weight of the composite fibrous material, and said first and said second discrete carrier webs are needle punched into mechanical interengagement with said discrete layer of said inorganic fibrous material.

4. A nonwoven composite fibrous material as set forth in claim 1, wherein said inorganic fibrous material is selected from the group consisting of mineral wool, glass wool, glass fibers, metal oxide fibers, carbon-graphite fibers and ceramic fibers.

5. A nonwoven composite fibrous material as set forth in claim 1, wherein said discrete carrier web is positioned in contact with a top surface of said discrete layer of said inorganic fibrous material further including a discrete scrim material positioned in contact with a bottom surface of said discrete layer of said inorganic fibrous material to support said bottom surface as said carrier web is being needle punched, and said carrier web is needle punched into mechanical engagement with said layer of said inorganic fibrous material and into said scrim material.

6. A nonwoven composite fibrous material as set forth in claim 1, wherein said inorganic fibers of said carrier web are selected from the group consisting of glass fibers, metal oxide fibers, carbon-graphite fibers and ceramic fibers.

7. A nonwoven composite fibrous material as set forth in claim 1, wherein said organic fibers of said carrier web are selected from the group consisting of vinylidene chloride fibers, polyolefin fibers, polystyrene fibers, copolymer polystyrene fibers, acrylonitrile fibers, polyamide fibers, polyvinylchloride fibers, acetate fibers and polyester fibers.

8. A nonwoven composite fibrous material as set forth in claim 1, wherein a substantial portion of said inorganic fibers and said organic fibers of said discrete carrier web have a length greater than the thickness of said discrete layer of said inorganic fibrous material in said composite fibrous material.

9. A nonwoven composite fibrous material as set forth in claim 8, wherein said composite fibrous material has a thickness of about 1 to 2 inches so that said inorganic fibers and said organic fibers of said discrete carrier web which are needle punched to said discrete layer of said inorganic fibrous material extend completely through said layer.

10. A nonwoven composite insulation material comprising:
a discrete layer consisting essentially of mineral wool fibers, said layer having a preselected thickness, said mineral wool fibers of said layer being in an unbonded state;
at least one carrier web for bonding together said mineral wool fibers;
said carrier web including an admixture of inorganic fibers and organic fibers;
said inorganic fibers and said organic fibers being blended to form a nonwoven structure with said organic fibers thereof comprising about 1% or less by weight of said composite insulation material;
said carrier web being positioned with said layer of said mineral wool fibers; and said carrier web being needle punched to said layer of said mineral wool fibers to interlock said inorganic fibers and said organic fibers of said carrier web with said mineral wool fibers so as to bond together said mineral wool fibers and form said nonwoven composite insulation material.

11. A process for making a nonwoven fibrous material comprising the steps of:
blending inorganic fibrous material in a concentration by weight of at least about 90% with organic fibrous material to form at least one composite nonwoven carrier web of carrier fibers having a preselected thickness and density;
positioning said carrier web in contact with a layer of inorganic fibers, said layer comprising an unstructured concentration of said inorganic fibers of a preselected thickness and density; and needle punching said carrier web to advance said carrier fibers into interlocking relation with said inorganic fibers to bond together said inorganic fibers to form said nonwoven fibrous material having a preselected thickness and density and a content of said organic fibrous material of about 1% or less by weight.

12. A process as set forth in claim 11, wherein said carrier web constitutes as much as about 10% by weight of the total weight of said nonwoven fibrous material while said layer of said inorganic fibers constitutes at least about 90%
by weight of said total weight of said nonwoven fibrous material.

13. A process as set forth in claim 11, further including the steps of positioning a first of said carrier webs into overlying relation with said layer of said inorganic fibers, positioning a second of said carrier webs into underlying relation with said layer of said inorganic fibers, needle punching said first carrier web downwardly into mechanical interengagement with said layer of said inorganic fibers, and needle punching said second carrier web upwardly into mechanical interengagement with said layer of said inorganic fibers to bond together said inorganic fibers to form said nonwoven fibrous material.

14. A process for making a carrier web comprising the steps of:
providing a plurality of inorganic fibers;
providing a plurality of organic fibers;
coating said inorganic fibers to increase the surface friction of said inorganic fibers; and blending said coated inorganic fibers in a preselected concentration with said organic fibers to form said carrier web having a preselected thickness and density and containing about 10% or less by weight of said organic fibers.

15. A process as set forth in claim 14, wherein said preselected substance is selected from a group consisting of starch and silica gel.

16. A process as set forth in claim 14, further including the step of coating a surface of said inorganic fibers and a surface of said organic fibers with a preselected agent to eliminate the retention of static electricity on said surfaces.

17. A process as set forth in claim 14, further including the step of increasing a humidity of ambient air surrounding said inorganic fibers and said organic fibers to dissipate static electricity retained by said inorganic fibers and said organic fibers.

18. A process as set forth in claim 14, further including the step of spraying said inorganic fibers and said organic fibers with an anti-static agent prior to said blending.

19. A process as set forth in claim 18, wherein said anti-static agent is water.