WO2008005729A2 - Reducing formaldehyde emissions from fiberglass insulation - Google Patents

Abstract

A process for making a fibrous product using a binder based on a formaldehyde-containing resin and especially for making fiberglass insulation products, and to the fibrous products themselves, wherein the fibrous product [11] is placed in a mass transfer relationship with a formaldehyde scavenger, such as by having a backing sheet [12] affixed thereto arid the backing sheet [12] is coated or impregnated with a formaldehyde scavenger composition, or by isolating the insulation product in an enclosed space with a formaldehyde scavenger, with the result that the fibrous product [11] exhibits a reduced level of formaldehyde emission.

Description

REDUCING FORMALDEHYDE EMISSIONS FROM FIBERGLASS INSULATION

FIELD OF THE INVENTION

[01] The present invention relates to methods (and a related product configuration) for reducing formaldehyde emissions from articles prepared using formaldehyde- containing resins and relates especially to a method for reducing formaldehyde emissions from fiberglass products, such as fiberglass insulation.

BACKGROUND OF THE INVENTION

1_.02] Formaldehyde-based resins or formaldehyde-containing resins, such as urea- formaldehyde (UF) resins, phenol -formaldehyde (PF) resins, including PF resins extended with urea (PFU) and melamine- formaldehyde (MF) resins find widespread use as adhesives and bonding agents for making a wide variety of products.

[03] For example, PF and PUF resins in particular have been the mainstays of fiberglass insulation binder technology over the past several years. Such resins are inexpensive and provide cured fiberglass insulation products with excellent physical properties.

[04] Fiberglass insulation, used generally in an uncompressed mat or blanket form, provides heat insulation for roof and wall structures in residential and commercial buildings, and is used in a compressed form as insulation for pipes and other conduits, and also is used in a variety of other molded forms.

[OSI Such fiberglass insulation products are easy to install and provide an economical and effective insulating barrier to reduce heat loss through the roof and wall structures of buildings and through the surface of pipes and other conduits or containers used to contain hot or cold fluids and other materials.

[06] Fiberglass insulation mats and blankets often are shipped in a compressed, rolled form to facilitate transportation and reduce costs. When such compressed bundles of fiberglass are used at a job site, it is important that the compressed fiberglass product recover a substantial amount of it pre-cornpressed thickness. If not, the product will suffer a decrease is its thermal insulation and sound attenuation properties. Fiberglass insulation made with PF and PFU resins is able to recover most of its pre-compressed thickness, thus contributing to the wide acceptance of these resins as binders in this application.

[07] Fiberglass insulation suppliers, such as Guardian and Owens-Corning, also make fiber glass loosefill insulation products. One particular product is marketed by Guardian as Supercube II®. Another product is marketed by Owens-Corning under the name Advanced ThermaCube Plus®. Such products also can be made using a PF or PFU resin adhesive. To make loosefill insulation products, including these products, fiberglass mats or blankets can be ground or "cubed" into smaller pieces. The insulation (also referred to as blowing wool) can also be packaged in a compressed form encased in a plastic wrapping to facilitate transportation and reduce costs. The loosefill insulation, such as in the form of "cubes," facilitates installation into hard-to-reach areas and under conditions where there is limited space for human egress. The discrete insulation "cubes" are able to efficiently fill nooks and crevices to provide complete insulation coverage.

[08] The ability of these formaldehyde-based resins to provide the necessary performance benefits at a reduced cost relative to other adhesive technologies has thus made formaldehyde-based resins, including UF, PF and PUF resins, popular in a variety of products that find their way into commercial and residential uses. [09] One of the drawbacks of using these resins, both for making insulation and for other consumer products, however, is the potential for formaldehyde emissions from the finished article. It has long been observed that gaseous formaldehyde is released from such articles, some of which is attributable to unreacted formaldehyde in the cured resin binder and some of which is attributable to degradation or decomposition products generated over time under acidic conditions, elevated temperatures, and/or high humidity.

[10j Thus, there is a continuing need for new methods for reducing formaldehyde emission in products produced using formaldehyde-based or formaldehyde- containing resins,

[11] One of the common forms of conventional fiberglass insulation is an elongated mat or blanket of uniform width and thickness, having a backing sheet, possibly of a vapor impervious material, adhesively secured to one side surface of the mat or blanket. This mat or blanket often is formed in a continuous process by compressing the fiberglass mat or blanket against an adhesively coated surface of the backing sheet material. Such a method is an economical and an efficient means of forming a conventional fiberglass insulation product that is easy to handle and install. The present invention provides one embodiment that takes advantage of this conventional product configuration to produce fiberglass insulation products having a reduced tendency to emit formaldehyde into the environment.

BRIEF DESCRIPTION OF THE DRAWINGS

[12] Figure 1 schematically illustrates a typical way of making a wide variety of fiberglass insulation products, which can be modified in accordance with the present invention to have a reduced tendency to emit formaldehyde. [13] Figure 2 illustrates one fiberglass insulation product according to the present invention, shown is a cross-sectional view, taken along line 2 — 2 of Figure 3.

[14] Figure 3 is a schematic illustration of an apparatus and process for forming a fiberglass insulation product of the present invention,

[15] Figure 4 schematically illustrates another embodiment of the method of the present invention for treating a fiberglass insulation product to reduce its tendency to emit formaldehyde.

DETAILED DESCRIPTION OF THE INVENTION

[16] The present invention is directed to methods for reducing the amount of formaldehyde emitted into the surrounding environment by a product made with, or otherwise containing a formaldehyde- containing resin binder.

[17] The invention is directed specifically to methods for reducing the amount of formaldehyde emitted into the surrounding environment by fiberglass insulation products made using a formaldehyde- containing resin binder.

[18] The invention also is directed to a packaged fibrous product that has a reduced tendency to emit formaldehyde, such as a packaged fiberglass insulation product.

[19] According to one aspect of the invention, the fiberglass insulation is provided with a backing sheet, wherein the backing sheet is coated or impregnated with an effective amount of a formaldehyde-scavenging composition placed in mass transfer contact with the formaldehyde-emitting fiberglass insulation. The presence of the formaldehyde scavenger-coated or impregnated backing sheet serves to trap formaldehyde, preferably through a covalent interaction, that is emitted by the fiberglass insulation and this trapping reduces the level of formaldehyde emitted from the insulation.

[20] According to another aspect of the present invention, a formaldehyde scavenger is added separately to a packaged insulation product. The insulation is packaged in a way to isolate it from the general environment, such as by enclosing it in a plastic wrap or plastic bag to hermetically seal it from the ambient environment. The scavenger can be introduced into the isolated insulation product in a number of ways, such as by being impregnated on or in a substrate (such as being impregnated in a backing sheet in those instances where the insulation is provided with a backing sheet) or as a gas. This aspect of the invention will be described in more detail hereinafter. As used throughout the specification and in the claims, the phrase "hermetically seal" and similar phrases does not require an air-tight configuration and is intended to refer to any construction that suitably prevents the undesired escape of any significant fraction of the formaldehyde scavenger from the enclosed space so that that the scavenger can satisfactorily serve its scavenging function.

[21] As used herein, the phrase "formaldehyde-containing resin" or "formaldehyde - based resin" means a resinous, thermosetting composition made from a molar excess of formaldehyde and one or more formaldehyde- reactive monomers such as phenol, urea, acetone, melamine and the like. Such resins typically contain free, i.e., unreacted formaldehyde, and exhibit formaldehyde emissions both during their cure and in the absence of an effective treatment, following their cure. Such resins are well known to those skilled in the art and do not require a detailed description. Such resins are commercially available from resin suppliers such as Georgia-Pacific Resins LLC, Atlanta, GA. The specific nature of the formaldehyde-containing resin does not form a part of the present invention.

[22] One formaldehyde-containing resin commonly used in connection with the manufacture of a wide variety of products including fiberglass insulation is made by reacting a molar excess of formaldehyde with phenol in the presence of an alkaline catalyst such as sodium hydroxide. Before this resin is used, it is commonly premixed with urea and the urea is allowed to react with residual formaldehyde, such as for 4-16 hours, to form what is often referred to as a "prereact^" before the adhesive binder is prepared for making the fiberglass insulation. After the prereaction, the binder often is made by adding water, ammonium sulfate, dedusting oils, ammonium hydroxide, dye, etc.

[23] As used herein, "'curing," "cured" and similar terms are intended to embrace the structural and/or morphological change which occurs to an aqueous binder comprising a formaldehyde- contain ing resin, such as, for example, by covalent chemical reaction (crosslinking), ionic interaction or clustering, improved adhesion to the substrate, phase transformation or inversion, and hydrogen bonding when the resin is dried and heated to an infusible condition causing the properties of a flexible, porous substrate, such as a mat or blanket of glass fibers to which an effective amount of the binder has been applied, to be altered.

[24] The terms "applied," "coated" and "impregnated" are used throughout the application to characterize the physical relationship between the formaldehyde scavenger composition and the backing sheet or other substrate on to which the formaldehyde scavenger composition is applied and retained. The terms "coating" and "coated" are more apt terms to describe the form of the formaldehyde scavenger composition when applied on to impervious backing sheets or substrates. The terms "impregnating" and "impregnate" are more apt terms to describe the form of the formaldehyde scavenger composition when applied onto permeable or porous backing sheets or substrates into which the composition can saturate. Applicants intend such phrases as "applying a formaldehyde scavenger composition to a backing sheet," "application of a formaldehyde scavenger composition to a backing sheet,^" "a backing sheet carries a formaldehyde scavenger composition" and similar phrases to embrace both of these physical forms. [25] The term "cured binder" means the cured formaldehyde-containing resin which bonds the fibers of a fibrous product together. Generally, the bonding occurs at the intersection of overlapping fibers.

[26] By "reduced tendency to emit formaldehyde" and related phrases are meant that a product, such as fiberglass insulation or loosefill fibrous insulation pieces, exhibits a lower level of formaldehyde emission than the product would have exhibited if made with the same binder but in the absence of the formaldehyde scavenging technique, such as a method of the present invention,

[27] As used herein the terms "fiber," "fibrous" and the like are intended to embrace materials that have an elongated morphology exhibiting an aspect ratio (length to thickness) of greater than 100, generally greater than 500, and often greater than 1000.

[28] As used herein, "aqueous" means water and mixtures composed substantially of water.

[29] As used throughout the specification and claims, the terms "mat," "batt" and "blanket" are used somewhat interchangeably to embrace a variety of fibrous substrates of a range of thicknesses and densities, made by entangling short fibers, long continuous fibers and mixtures thereof. It also is known that these mats, batts, or blankets can be cubed or ground to produce related loosefill, blowing wool insulation products (one such loosefill insulation product is marketed by Guardian under the product name Supercube II© and another under the name Advanced ThermaCube Plus© blowing wool product by Owens-Corning). Particularly preferred are mats, batts, blankets and loose fill-type products made using heat resistant fibers and especially glass fibers. [30] As used herein the term "fibrous product" is intended to include porous products made by bonding fibers together with an adhesive binder prepared using a formaldehyde-containing resin. Usually such fibrous products, whether in an uncompressed or in a compressed form, have a density of less than 300 Kg/m³. More often such products have a density of less than 200 Kg/nr . The method of the present invention is particularly useful for treating a packaged fibrous product having a density of less than 160 Kg/m³. The method of the invention has been shown to work especially well with products having a density of less than 120 Kg/m . Such fibrous products may be made from continuous fibers by swirling the endless filaments or strands of continuous fibers. Alternatively, the fibers may be chopped or cut to shorter lengths, or the fibers may be produced directly as short discontinuous fibers for mat, batt or blanket formation using techniques well known to those skilled in the art. Such techniques, though well known to skilled workers, form no part of the present invention. Use can also be made of ultra-fine fibers formed by the attenuation of glass rods. In addition to fibrous products made in the form of mats, batts and blankets, mention also can be made of other fibrous products such as duct board insulation and other molded insulation products. All of these fibrous products are characterized by having an internal, generally open porosity that harbors pockets of air that contributes to their acoustic and heat insulation capability. In such products, an amount of binder generally is applied sufficient only to fix the position of each fiber in the mat by bonding fibers where they cross or overlap and not to significantly interfere with the porosity of the product. Using binders with good flow characteristics allows the binder to flow to these fiber intersections. Thus, the binder composition is generally applied in the preparation of these fibrous products in an amount such that the cured binder constitutes about 1 % to about 20% by weight, more usually about 3 to 12% by weight of the finished fibrous product.

[31] As used herein the term "heat resistant fibers" is intended to embrace fibers suitable for withstanding elevated temperatures such as mineral fibers (e.g., basaltic fibers), aramid fibers, ceramic fibers, metal fibers, carbon fibers, polyimide fibers, certain polyester fibers, rayon fibers, and especially glass fibers. Such fibers are substantially unaffected by exposure to temperatures above about 120⁰ C.

[32] In a first aspect, the present invention is directed to a method for reducing the amount of formaldehyde that is emitted into the surrounding environment from a fiberglass insulation product manufactured using a formaldehyde-containing resin binder. A key feature of the method is the application of, e.g., the coating or impregnating of, a formaldehyde scavenger composition, often applied as an aqueous mixture comprising a formaldehyde scavenger, onto or into a substrate that is placed in a mass transfer relationship with the fiberglass insulation product, such as onto or into suitable for use as a fiberglass insulation backing sheet. In one embodiment, the formaldehyde scavenger-coated or impregnated substrate is then used as a backing sheet for the fiberglass insulation product.

[33] In another aspect, the present invention provides a fiberglass insulation product that comprises a non-woven association or agglomeration of fibers, typically heat resistant (e.g., glass) fibers, bonded together at a variety of densities with a cured formaldehyde- containing resin and having a substrate (e.g., backing sheet) positioned adjacent to the bonded fibers, wherein the substrate (e.g., backing sheet) is coated or impregnated with an amount of a formaldehyde scavenger composition sufficient to reduce the amount of formaldehyde emitted from the mat.

[34] In yet another aspect, the present invention is directed to a method for reducing the level of formaldehyde emission from a fibrous product, especially a fiberglass insulation product, which comprises isolating the fibrous product in an enclosed space, and introducing a formaldehyde scavenger into the enclosed space such as by injecting into the enclosed space a gaseous formaldehyde scavenger and maintaining the scavenger in the enclosed space for a time sufficient to reduce the level of formaldehyde emission. The gaseous formaldehyde scavenger and the fibrous product can be introduced into the enclosed space in either order,

[35] In still another aspect, the present invention is directed to a method for reducing the level of formaldehyde emission from a fibrous product, especially a fiberglass insulation product, which comprises surrounding or encasing the fibrous product with a film, e.g., by wrapping the fibrous product with a film such as a plastic film, and providing formaldehyde scavenger, especially a gaseous formaldehyde scavenger, in the so-enclosed space in contact with the fibrous product for a time sufficient to reduce the level of formaldehyde emission.

[36] In still yet another aspect, the present invention is directed to a method for reducing the level of formaldehyde emission from a fibrous product which comprises placing the fibrous product into a bag, such as a plastic bag, adding a formaldehyde scavenger into the bag, such as by injecting a gaseous formaldehyde scavenger into the bag, either before of after sealing the bag to allow the gaseous formaldehyde scavenger to be in contact with the fibrous product for a time sufficient to reduce the level of formaldehyde emission and sealing the bag.

[37] These and other aspects of the present invention will be described in the following specification with reference to specific embodiments. This application is not intended to be limited to these specific embodiments: but is intended to cover changes and substitutions that may be made by those skilled in the art without departing from the spirit and the scope of the invention as described further hereinafter.

[38] A first aspect of the invention will now be described with reference to Figure 1, which schematically illustrates a common glass fiber production system 10 that produces a wide variety of fiberglass insulation products thai can benefit from the present invention. [39] In this illustrated embodiment, the raw materials for glass fiber formation are blended in a blender 12 and fed from there into a molten glass fiber production system 14. Thereafter, fiber attenuation generally is performed by centrifuging molten glass though spinners 16 or by fluid jets (not shown) to form discontinuous glass fibers of relatively small dimensions. Using the spinner system 16, the molten glass is extruded through openings while air and/or other gases (gas/air attenuation 18) are blown onto the fibers. This process forms discontinuous glass fibers, and such systems are conventional and known to those skilled in the art.

[40] After glass fiber formation, a curable formaldehyde-containing binder is generally formulated as a liquid and is applied usually by spraying or fogging (sprayer 20) onto the hot glass fibers emerging from the fiber attenuation mechanism and the binder coated glass fibers are passed through a fiber distribution forming hood 22 for collection on a perforated conveyor belt 24. Gas and/or air blowing on the coated fibers in the fiber distribution forming hood 22 and on the conveyor belt 24 help dry the binder on the fibers and bind fibers together to form a glass fiber mat or blanket.

[41] The dynamics of the binder application is such that much of the water in the binder is evaporated as the hot fibers are cooled by contact with the aqueous binder. The resin binder then becomes tacky holding the mass of fibers together as the resin begins to set. The fibers are collected on a conveyor belt 24 in a generally haphazard manner to form a non- woven mat. The depth (thickness) of the fibers forming the mat is determined by the speed of fiber formation and the speed of the conveyor belt 24. The air or gas flowing through the assembly is exhausted to the atmosphere via exhaust system 26 (if necessary, after appropriate filtering or other treatment). [42] After leaving the fiber distribution forming hood 22, lhe binder-coated (or

"resinated") unciired glass fiber mat may be moved to various offline production steps or systems, as illustrated by path 28 in FIG. 1. For example, prior to curing, the glass fiber mat may be formed into pipe sections (uncovered 30 or covered 32), or otherwise molded into a desired shape 34. Curing of the binder can take place after the offline activities illustrated downstream from path 28 or coincident with the various shaping steps.

[43] As another alternative, after leaving the fiber distribution forming hood 22, the binder-coated uncured glass fiber mat material may be moved along path 36 to a curing oven 38. While a hugger belt type curing oven 38 is illustrated as an example in Figure 1, curing also may take place in a mold or in any other appropriate curing device, without departing from the invention. After curing, the glass fiber mat may be further processed in any appropriate manner. For example, as illustrated in Figure 1, various machining operations may take place at machining station 40, such as cutting, trimming, etc., and excess or non-used glass fibers (e.g., from a cutting or trimming operation) may be recycled back to the fiber distribution forming hood 22 along recycle line 42. Further processing may include glass fiber mat slab stacking 44 (e.g., for high density molded glass fiber products), mechanical rolling 46 (e.g., for low density glass fiber insulation products), or rolling and vacuum reducing 48 for distribution of compressed rolls of building insulation. Still another alternative is to subdivide, e.g., by cutting, the insulation batts into small pieces of an appropriate size (e.g., cubes of approx Vz" x Vi" x ¹Za") to use as blowing wool that can be blown for instance into attic spaces to insulate a home. (Blowing wool generally has twice the formaldehyde emissions compared to standard batt products)

[44] The formaldehyde-containing resin binder composition, after it is applied to the glass fibers, is heated to effect drying and curing. In the embodiment illustrated in Figure 1 , after the initial portion of this heating (primarily drying) which occurs as a resuit of the transfer of heat from the hot fibers to the aqueous binder applied to the fibers (as the recently formed hot glass fibers are cooled by the aqueous binder), the mat can be passed through an oven 38, The duration and temperature of the heating in the oven will affect the rate of drying, processability and handleability, degree of curing and property development of the resulting fibrous mat. The curing temperatures are usually within the range from 50 to 300° C, and preferably within the range from 90 to 270° C. and the curing time will usually be somewhere between 3 seconds to about 15 minutes. Of course, other temperaturevS and times can be used depending upon particular binder formulations and the present invention is not limited to any specific set of conditions,

[45] After processing, the uncured and/or cured glass fiber products may be moved to an appropriate location for storage, shipment, or other use, as generally illustrated by paths 50 and 52.

[46] These fibrous products can be formed as relatively thin products of about 1/8 to 1/4 inch or they can be formed as thick mats of 6 to 8 inches or even more. Depending on formation conditions, the density of the products also can be varied from relatively fluffy low density products (e.g., wall insulation or blowing wool) to higher densities of 2 to 10 pounds per cubic foot or higher (e.g., pipe insulation) , as is well understood by those skilled in the art.

[47] Continuous fibers also may be employed in the form of mats or blankets fabricated by swirling the endless filaments or strands of continuous fibers, or they may be chopped or cut to shorter lengths for mat, batt or blanket formation. .

[48] In fiberglass insulation products, heat resistant fibers generally are bonded together into an integral structure with an aqueous curable binder, typically an aqueous formaldehyde-containing resin. One particularly common resin within the group of formaldehyde-containing resins is the heat curable, i.e., thermosetting, resin systems of the phenol-formaldehyde (PF) type. Included within this group also are PF resins that have been modified by the addition of urea (PFU resins). These resins are typically synthesized in an aqueous reaction medium under alkaline reaction conditions, generally established using an alkali metal hydroxide and especially sodium hydroxide. In making these resins, phenol is reacted with a molar excess of formaldehyde, normally to a very low level of residual phenol. In the case of PFU resins, an amount of urea basically in an amount sufficient to react with the residual formaldehyde is subsequently added and is reacted, typically for about 4 to 16 hours.

[49] Another common class of formaldehyde-containing resins often used as a binder in making thin fiber products is the thermosetting urea-formaldehyde (UF) resins. UF resins also are reacted (produced) under alkaline or acid conditions depending on the desired end use. UF resins used in binder formulations for making fiber products, such as air filters which may be about one inch thick, also are commonly cured under acid conditions using a latent acid catalyst such as triethylamine sulfate.

[SO] Such formaldehyde- containing resins binders provide a strong bond between fibers, with sufficient elasticity and thickness-recovery to permit reasonable shipping and in-service deformation of the fibrous products, such as fiberglass insulation.

[51] As shown by the various options in Figure 1, the glass fiber mat may be compressed and shaped into a variety of different products, whether it is passed through a curing oven 38 or otherwise processed.

[52] As noted, the drying and curing functions may be carried out in two or more distinct steps, if desired. For example, the binder may first be heated at a temperature and for a time sufficient to substantially dry but not to substantially cure the binder composition and then heated for a second time at a higher temperature and/or for a longer period of time to effect curing (thermosetting). Such a preliminary "drying" procedure, generally referred to as "B-staging". may be used to provide binder-treated product, for example, in roll form, which may at a later stage be cured, with or without forming or molding into a particular configuration, concurrent with the curing process. This makes it possible, for example, to produce binder-impregnated semifabricates which can be molded and cured elsewhere.

[53] In accordance with the present invention, the fiberglass insulation product, whether a high density molded product (such as duct board used in constructing HVAC ducts), a roll of fiberglass insulation destined for use in insulating the walls of building structures, or a pipe insulation, may be provided with a backing sheet that carries a formaldehyde scavenger composition,

[54] Figure 2 illustrates, in cross-section taken along line 2—2 of Figure 3, a sheet of fiberglass insulation 10 constructed according to the present invention by affixing a backing sheet 12 to a fiberglass mat or blanket 1 1 made with a formaldehyde- containing resin binder. In this embodiment, the fiberglass mat or blanket 11 has a rectangular cross-section with an upper surface 14, a lower surface 16 and opposed parallel side surfaces 17. The fiberglass blanket 11 can be of almost any width so as to be compatible with the structure to which it is applied, and its thickness, for residential applications, usually will be between 3 to 16 inches.

[55] In accordance with the present invention, the backing sheet 12 can be any of a wide variety of suitable materials for forming a flat, often flexible, support layer, film or foil, including for example paper, cardboard, fabric, plastic (such as Mylar, polyethylene or polyvinyl chloride), metal (such as aluminum) and other similar materials. The sheet is generally flexible, but has a sufficient degree of inherent stiffness so as to provide the fiberglass mat or blanket 1 3 with stability. In many cases the sheet is made from a plastic or metal film to make it vapor impervious. The backing sheet 12 often has an adhesively coated inner surface 18 for attaching it to the fiberglass mat or blanket 11, a back surface 19 and opposed parallel side edges 20 and 21. The back surface 19 of the backing sheet 12 can be covered with one or more additonal layers of facing material if desired, such as a heavy gauge paper, particularly in those embodiments where a thin foil is used for an inner layer of backing sheet 12.

[56] Indeed, the backing sheet can have a single ply construction, or can have a multiply construction. The backing sheet can be made from a single material or can be made from a mixture of the various substrate materials as, for example, identified above.

[57] The backing sheet 12 has a width dependent on the width of the fiberglass mat or blanket 11. Preferably, the side edges 20 and 21 of the backing sheet 12 extend outwardly a small distance beyond the side surfaces 17 of the fiberglass mat or blanket 11 to form tabs of the backing material which facilitate installation. The fiberglass mat or blanket 1 1 can be installed in roof or wall structures of various types of buildings to provide an insulation barrier for such structures, with the tabs of the backing sheet being attached to studs or other parts of the building structure.

[58] In order to reduce the emission of formaldehyde from the fiberglass mat or blanket 11, the backing sheet 12 carries a formaldehyde scavenger composition. When using an impervious backing sheet material, the formaldehyde scavenger composition is coated on the inner surface 18 of the backing sheet. For porous backing sheets, the formaldehyde scavenger composition can either be coated on the inner surface 18, or can be impregnated though the thickness of the backing sheet 12. In this way, the formaldehyde scavenger composition is in a mass transfer relationship with the formaldehyde as it is emitted from the mat or blanket 12. While Figure 2 shows a backing sheet situated on only one side of the mat or blanket 11 , it is of course within the spirit of the present invention to provide a backing sheet on both sides of the mat or blanket 1 1. [59] Referring now to Figure 3, one process for affixing the backing material of the present invention to a fiberglass insulation mat or blanket is schematically illustrated.

[60] As illustrated in Figure 3, a sheet of backing material 12 is advanced along its length from a supply, typically provided as a roll of the material (not shown), in the direction indicated by arrow A. The backing sheet material passes over an adhesive applicator 25 that engages a surface of the backing sheet and applies an adhesive material to a surface 18 of the backing sheet. In embodiments where the backing sheet does not already carry a formaldehyde scavenger composition, the adhesive composition 41 in adhesive reservoir 38 may also contains a formaldehyde scavenger, so that both an adhesive for affixing the backing sheet 12 to the fiberglass mat or blanket 11 and a formaldehyde scavenger are simultaneously applied to the backing sheet 12. Alternatively, there could be a separate step where the formaldehyde scavenger is applied to the backing sheet 12, such as by use of a sprayer, before it engages the fiberglass mat or blanket 11.

[61] The backing sheet 12 is advanced around a pair of guide rollers 44 and 46 which reorient the backing sheet 12 such that the adhesively coated surface of the backing sheet (and the surface that carries the formaldehyde scavenger composition) 18 faces upwardly towards a fiberglass mat or blanket 11, which is advanced along its length from another supply, roll 45. onto the adhesively coated surface 18 of the backing sheet 12 so that the backing sheet 12 and blanket or mat 11 become adhesively attached.

[62] The fiberglass mat or blanket supply roll 45 rests on feed rolls 47, and the mat or blanket material 1 1 advances along its length feeding a substantially continuous length of fiberglass mat or blanket material 1 1 into contact with the adhesively coated surface 18 of the backing sheet 12. A blanket guide roller 48, about which the fiberglass blanket 11 passes, is positioned parallel to upper guide roller 46, between upper guide roller 46 and the fiberglass blanket feed rollers 47. The blanket guide roller 48 guides the fiberglass blanket 11 into contact with the adhesively coated surface 18 (and the surface that carries the formaldehyde scavenger composition) of the backing sheet 12 as indicated at 49.

[63] In an alternative embodiment for making fiberglass insulation products, the process could be arranged to deposit the formaldehyde-containing resin binder- treated fibers into a mold area through which a continuous sheet of backing material, such as paper or foil, which carries a formaldehyde scavenger composition, can be passed at any desired speed. The resin-treated insulation fibers can be deposited directly onto the backing material to any desired thickness. As the backing material continuously moves from the mold area it can pass through a drying oven to speed the setting of the adhesive. After passing from the drying oven the continuous strip of insulation can be rolled into a desired configuration for shipping or storage.

[64] As demonstrated in the following examples, applicants also have discovered that by placing a formaldehyde scavenger and especially a substrate that carries a formaldehyde scavenging composition, e.g., which is coated with, impregnated with or otherwise contains a formaldehyde scavenging composition, into a hermetically sealed package (Ziplock®-type storage bags were used in the examples) along with the fiberglass insulation product, one can obtain a significant reduction in the level of formaldehyde emissions from the product. That same principle can be applied to other fiberglass products made with a formaldehyde-containing resin binder, which are not provided with a backing sheet. Thus, the present invention also is directed to a method for reducing the formaldehyde emission from a fibrous product, especially a fiberglass insulation product, in which a scavenger is isolated with the fibrous product in a hermetically sealed space.

[65] In particular, in order to implement the technique of the present invention is this context, fiberglass products, made with a formaldehyde-containing resin, are packaged in a way to isolate the products from the environment. The products can be suitably isolated by encasing them in a sealed plastic film, by placing them in a plastic bag, or by wrapping them with a similar packaging material. Other ways of encasing the product so as to isolate it hermetically from the environment will be apparent to those skilled in the art. The goal is to encase the formaldehyde-emitting product in a substantially airtight package. By "substantially airtight" is meant that the formaldehyde-emitting product is isolated from the environment in a way to restrict access into and egress out from the package. Placed inside the sealed package, along with the fiberglass insulation product, is a formaldehyde scavenger, easily supplied in one embodiment by using a substrate carrying a formaldehyde scavenger composition.

[66] The substrate for use in this embodiment of the invention can take many forms and according to the broadest aspects of the present invention, the form of the substrate is not to be limited. For example, in addition to using a formaldehyde scavenger in a neat form, it is also contemplated that the scavenger can be introduced by using a paper saturated with a formaldehyde scavenger composition, by using a vial or porous packet containing a formaldehyde scavenging composition, for example, a solid form of a formaldehyde scavenger composition that is freely available to the isolated atmosphere of the package, and by using many other configurations. In an alternative embodiment, instead of placing what might be considered a separate substrate carrying the formaldehyde scavenger composition inside the package, the inner surface of the packaging material itself, i.e., the surface of the package exposed to the interior space of the package, would itself carry, e.g., would be coated or impregnated with a formaldehyde scavenger composition. Thus, in this embodiment, the inner surface of the packaging itself comprises a substrate carrying a formaldehyde scavenger and may be provides as a plastic film coated with a formaldehyde scavenging composition, or a metal foil coated with a formaldehyde scavenging composition. Still other ways of introducing the formaldehyde scavenger inside the packaging will be apparent to those skilled in the art and the present invention is not to be limited to any specific technique.

[67] Through such configurations, the formaldehyde scavenger composition is placed in a mass transfer relationship with the fiberglass insulation product and these two components are isolated in a substantially airtight manner from the ambient environment. Suitable air-tight configurations are intended to refer to any construction that suitably prevents the undesired escape of any significant fraction of the formaldehyde scavenger from the enclosed space so that that the scavenger can satisfactorily serve its scavenging function. It is not intended to be limited just to constructions where absolutely no interchange of gas from the enclosed space with the ambient atmosphere is possible. Once in this mass transfer relationship and isolated from the external environment, there is sufficient contact between the scavenger and the formaldehyde emitted by the product to reduce the amount of formaldehyde released into the environment from the product.

[68] In accordance with one preferred approach of this embodiment of the present invention for treating a fibrous product, especially a fiberglass insulation product, to reduce the tendency of the fibrous product to emit formaldehyde, the formaldehyde scavenger and especially a gaseous formaldehyde scavenger is introduced into the enclosed space with the fibrous product. Applicant has found that with this technique one surprisingly obtains a very efficient reduction in the tendency of the fibrous product to emit formaldehyde. Indeed, applicant has found that use of a gaseous formaldehyde scavenger in particular is so efficient in reducing the level of formaldehyde emissions from the fibrous product that only a small amount of the scavenger is needed to reduce the emissions to an acceptable level. Indeed, in testing done by applicants the formaldehyde emissions of an insulation product have been reduced to below the level of detection used to assess the formaldehyde emissions. The fibrous product thus treated contains a reaction product, formed by the reaction between the gaseous formaldehyde scavenger and free formaldehyde in the fibrous product, with the reaction product forming separate from the cured binder.

[69] This embodiment of the present invention is not to be limited to any particular technique for isolating or encasing the fibrous product in an enclosed space. While a rigid container, such as a tank or a box could be used, it is more convenient and less expensive to use a flexible container such as a bag. Alternatively, the fibrous product could be wrapped with a sheet or film of material to create the containing space about the fibrous product. Functionally, all that is required for this embodiment of the invention is to create a container volume or space in which the fibrous product is isolated, encased or inserted and suitably sealed such that a gaseous scavenger that is added or otherwise present in the space with the fibrous product is retained with little and preferably no loss of scavenger by leakage from the container volume or space. Thus, a fibrous product can be suitably isolated by encasing it in a sealed plastic film, by placing it in a plastic bag, by wrapping it with a similar packaging material, or by another similar technique. In this way, the mass transfer process that takes place as formaldehyde is emitted and captured by the scavenger also present in the bag (preferably a commingled gaseous scavenger) is optimized and/or accelerated.

[70] In the preferred embodiment in which as gaseous scavenger is used, the container volume or space for isolating or encasing the fibrous product can be constructed from any of a wide range of materials suitable for retaining the gaseous scavenger in the volume or space with little and preferably no loss of gaseous scavenger by leakage from the container volume or space during the time the scavenger reacts with free formaldehyde. Materials which can be suitably sealed and which themselves are inherently impervious to gaseous scavengers can be used. While normal construction materials such as a sheet meial, wood panels or gypsum board could be used, it is generally more convenient to use a film of paper, plastic or foil or some combination thereof in multi-ply configurations such as a metal foil-paper laminate. Plastic film wrapping, such as a polypropylene film, a polyethylene film, a polyvinyl chloride film, or a polyester film (e.g., Mylar), in sheet or bag form should generally be suitable. Indeed, one of the benefits of the present invention is that the typical way of packaging such fibrous products, and especially fiberglass insulation products, for commercial distribution using plastic packaging in sheet or bag form is easily adapted to the method of the present invention.

[71] This preferred embodiment of the invention will now be described with reference to Figure 4, which schematically illustrates a preferred method for reducing the level of formaldehyde emission from a fibrous product, such as fiberglass insulation. Again, while the invention is illustrated in connection with this specific embodiment, those skilled in the art will appreciate that the invention can be adapted for use in reducing the tendency of a fibrous product to emit formaldehyde in connection with the manufacture of a wide variety of other fibrous products that are prepared using an adhesive binder comprising a formaldehyde-containing resin. Also, the invention also can be practiced using a variety of other techniques for placing the formaldehyde scavenger and the gaseous scavenger in an enclosed space.

[72] Illustrated schematically in Figure 4 is one representative apparatus designed to implement this embodiment of the present invention. As shown in Figure 4, an enclosed space or container volume constituting bag 10 is filled with a fiberglass insulation product 22. The bag 10 has inserted into it an injection lance 1 1 for delivering the gaseous scavenger. Bag 10 may be made from one of a variety of plastic films such as polypropylene, polyethylene, polyvinyl chloride, polyester and the like. Lance 11 may have an opening at its end and may be provided with a tapered end to facilitate its entry into the enclosed space. Alternatively, lance 10 may have a series of openings (not shown) along its length to distribute the scavenger gas more uniformly throughout the contents of the bag. In yet another embodiment, several lances may be used, instead of a single lance as shown in the schematic drawing, in order to obtain a better distribution of the scavenger gas in and throughout bag 10. These and other such variations are within the skill of the ordinarily skilled worker.

[73] A seal plate and gasket combination 23 can optionally be used if there is a desire to ensure that the connection between the lance 11 and bag 10 is sealed, or is substantially air-tight. Testing has shown that such sealing may not be necessary. Other ways of establishing a seal between the gas injector (e.g., lance 1 1) and the enclosed space or bag 10 will be apparent to those skilled in the art. The bag of insulation may be of a loosefill insulation of the type marketed by Guardian as Supercube II® or by Owens-Coming as Advanced ThermaCube Plus®, it also may be a roll of insulation, insulation batt, or it may take another form, such as duct board.

[74] The injection lance 1 1 is connected by a gas hose 12 to a gas charge container 13. The gas charge container may simply be a suitably sized cylinder. Other arrangements for supplying a set, fixed amount of a gaseous scavenger into the enclosed space will be evident to a skilled worker. Flow of gas into and out of the gas charge container 13 is regulated in part by solenoid valves 14 and 15, whose operation is controlled by controllers 16 and 17 via control lines 16a and 17 a, respectively. For safety, the operation of these valves should be interlocked so that sulfur dioxide is not inadvertently discharged through the system when the gas charge container is being filled. On the inlet side of the gas charge container 13 is gas supply tubing 18, which is connected to a gas supply source 21, such as a gas cylinder (not shown) containing the gaseous formaldehyde scavenger, such as sulfur dioxide or ammonia. Gas flow into the bag could also be accomplished using a cylinder with a plunger. The gas also could be delivered by having a plunger assembly push the gas into the bag. This and other injection methods will be evident to skilled workers.

[75] As will be described below, the formaldehyde scavenger may be supplied as a mixture of the active scavenger gas and an inert carrier or dilution gas. An alternative gas supply line 19 is shown in shadow in Figure 4. The gas supply line 19 is controlled by a solenoid valve 20 and a solenoid controller not shown, for supplying a source of carrier or dilution gas in the event that the gas supply of scavenger from source 21 through gas supply tubing 18 is not supplied premixed with a carrier or dilution gas.

[76] The system operation is very straightforward. Gaseous scavenger, preferably gaseous sulfur dioxide (or a premix of gaseous sulfur dioxide and a carrier gas such as nitrogen) is supplied from a gas supply source 21. such as a pressurized gas cylinder, to the gas charge container 13 by opening the inlet solenoid valve 14 on the pressurized side of the container 13. The flow of gas into the container 13 is stopped by a preset pressure controller 16 at the pressure providing the desired quantity of the charge. At this point, the inlet valve 14 is closed. The contained gas can thereafter be charged, or injected, into the enclosed space, such as bag 10, containing the fibrous insulation product to be treated with the scavenger. This is accomplished by placing the injection iance 11 into the receptacle 10 containing the insulation product (as shown) and opening the outlet container valve 15. The lance can be inserted into an opening of the bag before it is sealed for subsequent, storage, distribution and sale. It also is possible to insert the iance 1 1 after the bag has been readied for storage, distribution and sale simply by piercing or puncturing the wall of the previously sealed bag with lance 1 1. This allows the gas to expand into the receptacle 10 through supply tubing 12 and the lance 11. The outlet valve 15 is then closed, and the cycle repeated for subsequent injections of gaseous scavenger into additional bags of insulation.

[77] As the injection lance is removed from a bag 10 (if provisions for securing the lance are not otherwise provided), some residual sulfur dioxide gas may escape from the lance 1 1 and tube 12 into the surrounding environment. If this is undesired, this result could be prevented by providing a separate fugitive gas collection system (not shown) for the lance as it is removed from the treated bag 10. Alternatively, the apparatus also could be adapted to perform a separate cycle step in which an interim charge of an inert carrier gas {e.g.. a short blast of compressed air or nitrogen) is provided after the charge of gaseous scavenger, in order to purge residual scavenger, e.g., sulfur dioxide, from the supply tube 12 and the lance 11 into the receiving receptacle 10. For example, this could be accomplished using supply line 19 and solenoid 20 in combination with solenoid 15, as will be recognized by a skilled worker.

[78] Applicant has observed that implementing this embodiment of the present invention with as little as 0.12 g sulfur dioxide per Kg of insulation has reduced the equilibrium level of formaldehyde emission from a blowing wool fiberglass product (as measured using the Dynamic Micro Chamber procedure - see the following examples) from 338 ppb to a non-detectable level. While one has a wide latitude in establishing an upper limit on the amount of the gaseous scavenger to use in the broad practice of this embodiment of the present invention, based on considerations of safety and cost, applicant contemplates using anywhere from 0.03 g to 10.0 g of a gaseous formaldehyde scavenger, and preferably gaseous sulfur dioxide, per Kg of insulation. More preferably, applicant contemplates using from 0.06 g to 5.0 g of a gaseous formaldehyde scavenger, and preferably sulfur dioxide, per Kg of insulation. Usually, applicant expects to use from 0.08 g to 0.5 g of a gaseous formaldehyde scavenger, and preferably sulfur dioxide, per Kg of insulation. As noted above, it is convenient to introduce the formaldehyde scavenger into the enclosed space holding the fibrous product using a carrier or dilution gas. This technique provides several advantages. It facilitates delivery of a desired amount of the scavenger gas into the enclosed space and accordingly minimizes waste of the scavenger gas. It also reduces the potential safety hazard associated with any unintentional exhaust of the scavenger gas from the enclosed space.

[79] As noted earlier, the present invention prefers the use of sulfur dioxide as the gaseous formaldehyde scavenger. Based on testing conducted in connection with the scavenging of formaldehyde from fiberglass insulation using the method of the present invention, applicants have observed that sulfur dioxide is more effective than ammonia for reducing the level of formaldehyde emissions from a fiberglass insulation product. In addition, the reaction product that is formed by reaction between sulfur dioxide and formaldehyde is more stable and less odiferous than the corresponding aπimonia-formaldhyde product. Indeed, given applicants' discovery of the effectiveness of sulfur dioxide in reducing formaldehyde emission from packaged insulation products and based on testing conducted in connection with the scavenging of formaldehyde from a packaged commercially available fiberglass insulation product using the method of the present invention, applicants have shown that sulfur dioxide injection for scavenging formaldehyde emissions can be integrated easily as part of the commercial packaging (bagging) operation for distributing fiberglass for commercial and residential installation. As a result, the present invention provides an essentially transparent solution to reducing formaldehyde emission from fiberglass insulation products.

[80] Materials to be used in constructing the injection system schematically illustrated in Figure 4, suitable for handling the desired scavenger gas, be it the prefeiτed sulfur dioxide or ammonia, will be apparent to a skilled worker and need not be identified in the present application. Suffice it to say that the corrosive nature of such gases may necessitate a proper selection of materials of construction to ensure extended trouble-free operation. Such features are within the skill of the ordinarily skilled worker.

[811 Suitable formaldehyde scavengers for use in the broad practice of the present invention, such as for preparing the formaldehyde scavenger composition used to coat or impregnate a substrate such as a backing sheet, for example, by using an aqueous mixture of the formaldehyde scavenger, include singly or in combination such materials as urea

, low ratio melamine resins, i.e., melamine- formaldehyde resins made with a molar excess of melamine, sodium bisulfite, sodium metabisulfite, other alkali metal and alkaline earth metal bisulfites, sodium sulfite and other alkali metal and alkaline earth metal sufites. ammonium bisulfite, ammonium sulfite, resorcinol, polyacrylamicle, acrylamide, methacrylamide, melamine, biuret (HNI(H₂N)C=O]₂). triuret (Nf(H₂N)C=Oh) , biurea (I HN(J-^N)C=O]₂), polyurea, acid salts of aniline, aromatic amines, aliphatic amines, diethylene triamine, triethylene tetraamine, tetraethylene pentaraine, other polyamines and their salts, ammonia, polyamidoamines, amino acids, aromatic amino acids such, as glycine, p-amino benzoic acid, ammonium bicarbonate, ammonium carbonate, polyethyleneamines, sodium sulfamate, ammonium sulfamate, methane sulfonamide, succinimide, dicyandiamide (NCNH(H₂N)C=NH). sulfur compounds with valence state other than +6 including sulfur dioxide, ammonium sulfite, proteins (for example: soy, animal and plant proteins), an aminopolysaccharide, such as chitosan, thiourea ((H₂N)₂C=S), guanadine((H₂N)₂C=NH), sodium salts of taurine, sulfanilic acid, disodium salt of glutamic acid, zeolites, permanganate and similar materials.

[82] Depending on the particular embodiment, certain scavengers will likely exhibit more effective treatment. Optimal selection of a particular scavenger can generally be accomplished using routine experimentation. Particularly preferred formaldehyde scavengers are tetraethylene pentamine, sulfur dioxide and sodium bisulfite (and the related material sodium metabisulfite).

[83] An aqueous mixture of a formaldehyde scavenger (or formaldehyde scavengers) is prepared simply by mixing the scavenger (or scavengers) with water. The concentration of formaldehyde scavenger in the aqueous mixture can vary within wide limits (and is usually influenced by the aqueous solubility or miscibility of the scavenger), provided the amount does not interfere with the technique chosen for applying the aqueous mixture to a substrate, such as a backing sheet material. Application of a formaldehyde scavenger composition onto or into a substrate is generally accomplished by one of a variety of conventional coating techniques such as, for example, air or airless spraying, padding, saturating, roll coating, curtain coating and other similar techniques. The present invention is not to be limited to the specific way in which the formaldehyde scavenger is applied onto or into a substrate, such as a backing sheet material or another substrate.

[841 Usually, when using an aqueous mixture to impregnate or coat a substrate material, the aqueous mixture contains from as little as 0.01 % by weight to as much 99 % by weight or more of the formaldehyde scavenger, depending in many cases on the aqueous solubility or miscibility of the particular scavenger. Obviously, if the scavenger is used in a neat form, such as may be the case when using tetraethylene pentamine, which itself is a liquid at ambient conditions, the formaldehyde scavenger composition may be 100 % scavenger. Thus, the present invention is not limited to any specific level of scavenger whether supplied as an aqueous scavenger mixture, or not.

[85] The specific technique used to apply a formaldehyde scavenger composition to a substrate, such as a backing sheet material, including such materials as paper, cardboard, fabric, glass mat, plastic, metal or a similar foil or film material, can be similar to those techniques that are commonly employed in papermaking operations to apply a sizing composition to the surface of a paper product. Depending on the particular scavenger being used, either a neat scavenger in a liquid form, or more usually an aqueous formaldehyde scavenger composition, may be applied to a surface of the substrate, such as a backing sheet using a size press, by maintaining a puddle of the formaldehyde scavenger composition though nip rolls, or by flooding a surface of the backing sheet material with the assistance of a doctor knife blade. For example, a web of backing sheet material can be conducted through the nip of a roller-coater apparatus (various configurations are available), where the scavenger is applied. Alternatively, the formaldehyde scavenger composition may be sprayed onto the web of the backing sheet or can be applied by dipping the backing sheet into an aqueous composition of the formaldehyde scavenger, or by using one of the wide variety of conventional coating techniques known to those skilled in the art. Backing sheet material that is treated with a scavenger, such as an aqueous mixture of a scavenger, is then dried as needed at an elevated temperature to produce a backing sheet carrying the scavenger composition.

[86] The nature of the substrate, such as a backing sheet influences whether the substrate, or backing sheet material is coated or impregnated with the formaldehyde scavenger composition. Non-porous or impermeable substrates and backing sheets will receive only a surface coating of the formaldehyde scavenger composition. In contrast, porous substrates will tend to be impregnated at least partially through the thickness of the backing sheet depending upon the porosity of the substrate and the rheological property of the formaldehyde scavenger composition. For example if a paper or cardboard material is used as the substrate or backing sheet material, the formaldehyde scavenger composition might also be added at the wet end of the paper-making process itself. In this way the total thickness of the substrate or backing sheet material can be impregnated with the formaldehyde scavenger composition.

[87] Application of the formaldehyde scavenger to the substrate or backing sheet can be accomplished either as a post- product ion operation of making the backing sheet or as a portion of the backing sheet production process itself. The present invention is not limited to the way in which the formaldehyde scavenger composition is applied onto, or impregnated into, the substrate or backing sheet material.

[88] The formaldehyde scavenging composition is applied onto or impregnated into the substrate or backing sheet material in an amount such as to provide an effective amount of the formaldehyde scavenger composition for trapping or removing formaldehyde emitted from the fiberglass insulation product. Preferably, the formaldehyde scavenger composition is applied in an amount of about 0.1 wt. % to about 200 wt. % (on a dry basis) based on the weight of the substrate or backing sheet material. Usually, the level is about 1 wt. % to about 70 wt. 9c, and most often from about 2 wt. % to about 50 wt. %. [89] A key advantage of the present invention is that because the application of the formaldehyde scavenger is independent of and not commingled with the formaldehyde-containing resin binder, the level of addition of the scavenger does not adversely impact the tensile properties of the cured binder essential for obtaining a fibrous mat with acceptable physical properties. As shown in the following examples, including high levels of the formaldehyde scavenger directly in the binder formulation (internal scavenger), as taught in the prior art, not only fails to adequately reduce the tendency of the cured product to emit formaldehyde but also disadvantageously reduces the tensile properties of the cured product.

[90] Even though the formaldehyde scavenger is not intimately associated with the formaldehyde-containing resin binder, applicants have observed that placing the scavenger in a mass transfer relationship with the fiber mat on or in a substrate such as on or in the backing sheet of the mat, provides sufficient mass transfer contact between the scavenger and the formaldehyde emitted by the mat to reduce the amount of formaldehyde released into the environment. Indeed, in experiments they have conducted applicants have observed a reduction in formaldehyde emission to a non-detectable level.

[91] In some cases the formaldehyde scavenger may be a solid that can be melted to produce a molten liquid and the present invention contemplates applying such a molten form of the formaldehyde scavenger to the substrate or backing sheet material. In the case of a molten liquid, the scavenger can be sprayed or dripped on to the substrate or backing sheet substrate. In the case of a solid form of the scavenger, the scavenger also can be applied as small particles that either can be retained within the porosity of a porous substrate or backing sheet material such as paper (such as when a filler is commonly added during the preparation of paper), or can be affixed with the separate application of an adhesive to the surface of the substrate or backing sheet material (much like the attachment of abrasive particles to a backing sheet when preparing sand paper). Preferably, a non-formaldehyde-containing adhesive binder is used for affixing such solid particles as a surface coating on the substrate or backing sheet material.

[92] Particles that pass through a 3 Mesh screen (Tyler Screen designation) but are retained by a 100 mesh screen generally should be suitable for such uses. Other suitable particle sizes to use, depending on the specific embodiment contemplated, will be apparent to those skilled in the art. The particles can be mixed with a binder formulation or can be sprinkled onto a substrate or backing sheet material coated with the wet binder formulation. Alternatively, the scavenger could be loaded onto an inert carrier material, such as by coating or absorbing the scavenger, for example using an aqueous solution, onto sepiolite, activated carbon, activated carbon fibers, zeolite, activated alumina, vermicυlite. diatomaceous earth, perlite particles or cellulose fibers, with the scavenger- loaded inert material then being applied to the substrate or backing sheet material.

[93] To accelerate the scavenging action of the substrate and especially a backing sheet it is preferable to place the fiberglass insulation into a substantially hermetically sealed package (as shown below, Ziplock®-type storage bags are used in the examples) with the substrate. In particular, the fiberglass insulation product along with a scavenger coated or impregnated substrate, such as a backing sheet, wherein the backing sheet is coated or impregnated with an effective amount of a formaldehyde-scavenging composition, preferably is packaged in a way to isolate the product from the environment. The product can be suitably isolated by encasing it in a sealed plastic film, by placing it in a plastic bag, by wrapping it with a similar packaging material, or by another similar technique. In this way, the mass transfer process that takes place as formaldehyde is emitted and captured by the scavenger is optimized and/or accelerated.

[94] The formaldehyde scavenger composition used in connection with the present invention may, in addition to the formaldehyde scavenger itself, contain one or more additives to provide desired characteristics to the composition. Suitable additives include, but are not limited to, dyes and pigments, humectants or moisturizers, preservatives, antimicrobial agents, corrosion inhibitors, surfactants or wetting agents, pH buffers, viscosity control agents, mutual solvents and combinations thereof. Use of any particular additive, or any specific combination of additives, will depend on the actual formaldehyde scavenger selected and the particular way in which the composition is to be employed. Considerations influencing the preparation of a suitable formaldehyde scavenger composition are well within the skill of the art.

[95] For example, there is some indication that in some embodiments the performance of the formaldehyde scavenger applied in accordance with the present invention may be improved by the presence of a moisturizer or humectant. The moisturizer or humectant could simply be the humidity available in the ambient environment, or may be a polyol, or any other liquid, preferably a low volatility liquid, added a part of a formaldehyde scavenger composition, For example, the moisturizer could simply be water added as part of an aqueous solution of a formaldehyde scavenger, a polyol, such as glycerine, propylene glycol, trimethylol propane, or diethylene glycol, a polymine, an amine salt, calcium chloride and other deliquescent materials, polyacrylamides and other super absorbent materials, starch or other liquid. Such as low volatility liquids, may be applied as part of the formaldehyde scavenger composition to a substrate such as a backing sheet or another substrate. In cases where the scavenger is applied as an aqueous solution and dried, applicants suspect that residual moisture in the dried scavenger coating, enhanced by the presence of a polyol, or other moisturize, may assist the formaldehyde-reducing performance of the scavenger.

[96] Applicants have also observed that when using sodium bisulfite as a scavenger for fiberglass insulation made with PFU resin binder that the sodium bisulfite scavenger has an ameliorating effect on color development observed in the mat. In particular, mats having a cured PFU resin binder typically develop what can be characterized as a dark or dingy yellow color. When such mats are treated with a sodium bisulfite scavenger, the yellow color becomes lighter or more muled as the level of treatment increases. One benefit of this effect is it become easier to color the mat a different color (such as pink or blue) by supplying a dye or pigment as part of the manufacturing process. Less treatment may be needed to color the more lightly colored mats produced when using the formaldehyde scavenger treatment of the present invention.

[97] Fibrous products made in accordance with the present invention may be used for applications such as, for example, insulation batts, blowing wool, rolls, molded parts, as reinforcing mat for roofing, flooring, or gypsum applications, as air filters, as roving, as microglass -based substrate for printed circuit boards or battery separators, as filter stock, as tape stock, and as reinforcement scrim in cementitious and non-cementitious coatings for masonry.

[98] Fibrous products and especially fibrous insulation products, including those made from heat resistant fibers such as glass fibers, come in many shapes and densities. Thermal batt insulation may be unfaced or faced with a variety of materials such as Kraft paper, aluminum foil-Kraft paper or a fabric. Usually, these products have an uncompressed density of less than 50 Kg/nr . Fiber glass loosefiU or blowing wool, including material such as Guardian Supercube II® loosefill insulation or O wens- Coming's Advanced ThermaCube Plus® loosefill insulation, generally have a similar uncompressed density. Even compressed, such products generally do not exhibit a density above about 300 Kg/m³. Insulation boards made from glass fibers may have a density of at least about 50 Kg/m³, and often as high as 100 Kg/m³ and higher. Other molded insulation products may have a density as high as 130 Kg/m³ and higher. Still other insulation products that can be treated in accordance with the present invention will be apparent to those skilled in the art,

[99] The preparation of these and other insulation products, such as pipe insulation or HVAC duct insulation, or other molded insulation products made using formaldehyde-based adhesive resin binders will be understood by those skilled in the art based on this disclosure and forms no part of the present invention. The methods of the present invention can be used as a way for treating all such products to reduce their level of formaldehyde emission.

[100] Heat resistant fibrous products, including glass fiber insulation products, may also contain fibers that are not in themselves heat-resistant such as, for example, certain polyester fibers, rayon fibers, nylon fibers, cellulose fibers and super absorbent fibers, in so far as they do not materially adversely affect the performance of the fibrous product. In any event, the method of the present invention has applicability for reducing the level of formaldehyde emissions from a wide variety of fibrous products made using a formaldehyde-based adhesive resin binder.

[101] As recognized by those skilled in the art, not all fiberglass products are provided with backing sheets. Fiberglass products that may lack a backing sheet include low density rolled fiberglass insulation, blowing wool, some pipe insulation products and certain molded insulation products to name a few. Fortunately, such products that are made with formaldehyde-containing resins can still benefit from the improved method of reducing formaldehyde emissions developed by the present inventors and described in the present application.

[102] Embodiments of the present invention where a separate substrate laden with a formaldehyde scavenger is introduced into a sealed enclosure with the formaldehyde-emitting product are illustrated in the following examples.

[103] As noted above, in one embodiment of the present invention a gaseous formaldehyde scavenger is advantageously employed. Selection of a particular gaseous scavenger, be it sulfur dioxide or ammonia, for any particular application can generally be accomplished using routine experimentation. When using sulfur dioxide, the reaction with free formaldehyde is similar to that observed when reacting formaldehyde with a metabisulfite salt, which leads to the formation of the corresponding salt of hydroxy-sulfonic acid (please see Formaldehyde, Walker, J. Frederic, 3^rd Ed. pp. 251-253). For that and other reasons, use of SCh is a preferred gaseous scavenger.

[104] In a further embodiment, prior to a gaseous treatment according to the present invention, the fibrous product (insulation product) may also have been treated using another formaldehyde scavenging technique aimed at reducing the level of formaldehyde emissions from the product. Particularly contemplated as a method for pre-treatment in this regard are the other techniques described herein or a combination of techniques including those described in previously filed U.S. patent applications Serial Nos. 11/466,535 filed 23 August 2006, 11/478,980 filed 30 June 2006, 11/560.197 filed 11 November 2006 and 11/450,488 filed 9 June 2006.

[105] While not wishing to be bound by any particular theory, it is believed that the present invention maximizes the effectiveness of the gaseous scavenger for compiexing with formaldehyde by injecting the gaseous formaldehyde scavenger into an enclosed space with the fibrous mat.

[106] It will be understood that while the invention has been described in conjunction with specific embodiments thereof, the foregoing description and following examples are intended to illustrate, but not limit the scope of the invention. Other aspects, advantages and modifications will be apparent to those skilled in the art to which the invention pertains, and these aspects and modifications are within the scope of the invention.

COMPARATIVE EXAMPLE 1

[107] To simulate the manufacture of fiberglass insulation, batts were prepared in the laboratory as follows. A roll of 1 inch thick, un-bonded, fiberglass was obtained from Resolute Manufacturing and divided into individual sheets weighing about 30 grams. Individual un-bonded fiberglass sheets were placed in a tray. A formaldehyde-containing binder was placed into a reservoir and air was used to aspirate the binder into a fine mist. The mist was drawn through each individual batt using an air exhaust hood. This technique caused fine binder droplets to be deposited onto and into the batt. In each experiment, approximately eight grams of binder was deposited onto each sample of the glass batt. Following binder application, the batt was next cured in a forced air oven for two minutes at 425 ⁰F (218 ⁰C) to cure the binder. After curing, the batt was transferred to a Ziplock®- type storage bag until the sample could be tested using a consistent technique (emissions were collected using 20 mis of 0.25N NaOH in an impinger with the air flow into the impinger set at 1.0 1/min. and the impinger solutions were tested for formaldehyde emissions using a standard chromotropic acid method) in a dynamic micro chamber (DMC) to test its formaldehyde emission characteristic. A DMC is described in Georgia-Pacific Resins, Inc. U.S. Patents 5,286,363 and 5,395,494.

[108] Two batt samples were prepared (two replicates) for each of the experiments and testing examined two different treatment scenarios. In all cases, the binder was formulated from an aqueous phenol-formaldehyde resin that is commercially available from Georgia-Pacific Resins, Inc. as resin 209G47. The aqueous resin was mixed with a 40% by weight aqueous solution of urea in an amount of 1 part urea solution per approximately 7 parts aqueous resin. The mixture was allowed to "pre-react" overnight at room temperature before the binder was applied to the batts. Shortly before application to the batts, 1 part by weight of an aqueous ammonium sulfate solution (20 % by weight ammonium sulfate), as a cure accelerator or catalyst, was added per approximately 2 parts by weight of the binder to complete the base binder formulation.

[109] In the Control experiment, only the above-formulated binder was applied to the fiberglass batt. In a Comparative experiment, a formaldehyde scavenger (sodium bisulfite) also was added to the above-formulated binder and was dissolved in the binder shortly before the binder was applied to the halts. The scavenger was added to the binder in an amount of 1 part scavenger (sodium bisulfite) per approximately 17.6 parts of the aqueous resin used in the binder (this corresponds to 1 part scavenger per approximately 9 parts phenol-formaldehyde resin solids).

[110] The raw results of each of the two replicates obtained from the DMC testing for each experiment, the average results and the levels of reduction in formaldehyde emission are reported in Table 1 below. The internal scavenger provided a modest improvement in the formaldehyde emission characteristic of the fiberglass product.

Table 1 Formaldehyde Emission Results

(ppm Formaldehyde)

COMPARATIVE EXAMPLE 2

[111] The tensile strengths (dry and hot/wet) of glass mat hand sheets bonded using a typical phenol-formaldehyde resin binder was compared to hand sheets prepared with binders having sodium bisulfite, as a formaldehyde scavenger, added to the resin to assess the impact on tensile properties of an internal scavenger.

[112] Binders were formulated from an aqueous phenol-formaldehyde resin that is commercially available from Georgia-Pacific Resins, Inc. as resin 209G56. The aqueous resin first was mixed with a 40% by weight aqueous solution of urea in an amount of 1 part urea solution per approximately 1.8 parts aqueous resin. The mixture was allowed to "pre-react" overnight at room temperature to yield a pre- mix. Shortly before application to a glass mat, 1 part by weight of aqueous ammonia (28 % by weight ammonia); and 5 parts by weight of an aqueous ammonium sulfate solution (20 % by weight ammonium sulfate), as a cure accelerator or catalyst, were added per approximately 38 parts by weight of the pre-mix to complete the base binder formulation.

[113] In addition to testing the tensile properties of the base binder formulation

(designated the Control), two binder formulations also were prepared for testing one having an additonal 5 % by weight of sodium bisulfite added as a formaldehyde scavenger (designated Comparative A) and the other having an additional 50 % by weight of sodium bisulfite added (designated Comparative B), both as a percentage of binder solids (defined as resin solids plus urea solids).

[114] Various amounts of water were added to these binder formulations to yield a binder with the same amount of total binder solids (20 % solids as resin and urea solids). In particular, 1.78 parts water per part of premix was added to the Control, 1.76 parts water per part premix was added to complete the binder of Comparative A, and 1.55 parts water per part premix was added to complete the binder of Comparative B.

[115] Hand sheets were prepared by soaking the mats in the formulated binders and vacuuming excess resin binder off the mat. Following application of the various binders, each sample was cured in a forced air oven for two minutes at 401 ⁰F (205 ⁰C) to cure the binders.

[116] Tensile strengths (dry and hot/ wet) of hand sheets prepared using the various techniques (Control, Comparative A, and Comparative B) were determined. Dry tensile strengths of the mats were measured by subjecting samples of each hand sheet to breaking in a tensile tester (QC-1000 Materials Tester by the Thwing Albert Instrument Co.)- Hot/Wet tensile strengths of the mats were measured by initially soaking the hand sheets in 185° F (85° C) water for 10 minutes followed by breaking them in a tensile tester (QC-1000 Materials Tester by the Thwing Albert Instrument Co.) while the samples were still hot and wet. Fourteen (14) breaks for each sample were measured and the average of the breaking strengths was determined.

[117] The testing results are presented in Table 2. As shown, by using an internal scavenger, in the manner of Comparative A and Comparative B, increasing the level of added scavenger results in a degradation in tensile strength as compared to the Control Example.

Table 2 Hand Sheet Tensile Test Results

(lbs tensile strength)

EXAMPLE 3

1118] A fresh bag of unfaced R- 13 insulation, bearing product code 1685, was obtained from Knauf Fiberglass. This insulation product was prepared using a PUF resin binder. The insulation was cut into pieces of 8" by 20'^* and the pieces were immediately stored in individual Ziplock®-type storage bags.

[119] Blotter paper samples, 12" by 12", were obtained from Georgia-Pacific's paper group and were treated by saturating them with various solutions of sodium bisulfite and then dried in an oven. Two samples were impregnated with an aqueous solution of 33.3% by weight sodium bisulfite and then dried for one minute at 70⁰C. One sample contained 21.2 g of the treatment composition after drying (Sample A) and the other one contained 20.0 g (Sample B). Two other samples were impregnated with a 1:1-, by weight mixture of glycerine and an aqueous solution of 33.3% by weight sodium bisulfite and then dried for four minutes at 105 ⁰C. One sample contained 39.9 g of the treatment composition after drying (Sample C) and the other one contained 40.8 g (Sample D).

[120] After the blotter samples were prepared, each of them was cut in half to make two 6" by 12" pieces per sample and then each blotter paper sample was transferred to a Ziplock®-type storage bag containing the R- 13 samples. The samples were held for 72 hours at ambient conditions and then tested using the DMC protocol referenced m Comparative Example 1.

[121] Product formaldehyde emission results are presented below in Table 3. For the controls, an untreated piece of blotter paper was placed in the bag with the • insulation sample. The reported results are the averages obtained from all of the samples tested at a particular condition.

TABLE 3

Formaldehyde Emission Results

(ppb Formaldehyde)

''Less than 2 ppb

EXAMPLE 4

[122] Using the fresh unfaced R- 13 insulation of Example 3, the loss on ignition (LOl) value of the samples was estimated at 5% by weight. The 8" by 20'^" pieces of the R- 13 insulation weighed, on average, about 110 g. Thus, the organic fraction of each sample, at a 5% LOI, was about 5.5 g,

[123] Blotter paper samples, 6" by 6", were obtained from Georgia-Pacific's paper group and were treated by saturating them with various solutions of sodium bisulfite and then dried in an oven at 40 ⁰C for one minute. Two samples were impregnated with an aqueous solution of 0.55% by weight sodium bisulfite and then dried (Samples Al and A2), two samples were impregnated with an aqueous solution of 5.5% by weight sodium bisulfite and then dried (Sample Bl and B2) and two sample were impregnated with an aqueous solution of 33.3% by weight sodium bisulfite and then dried (Samples Cl and C2). Sample Al retained 8.1 g of the treatment composition after drying, while Sample A2 retained 7.8 g. Sample Bl retained 8.2 g of the treatment composition after drying, while Sample B2 retained 9.3 g. Finally, Sample Cl retained 9.7 g of the treatment composition after drying, while Sample C2 retained 10.6 g. [124] After the blotter samples were prepared, each of them was transferred to a

Ziplock<S)~tyρe storage bag containing the R- 13 samples. The samples were held overnight at ambient conditions and then tested the next morning using the DMC protocol referenced in Comparative Example L The samples from duplicate bags were placed into the DMC together (simultaneously),

[125] Product formaldehyde emission results are presented below in Table 4. For the Control, untreated pieces of blotter paper (Samples Xl and X2) were saturated with 10.0 g (Sample Xl) and 9.8 g (Sample X2) of water and dried in the same manner as the treated paper. Sample Xl retained 7.6 g of the water after drying, while Sample X2 retained 7.4 g.

Table 4 Formaldehyde Emission Results

(ppb Formaldehyde)

EXAMPLE 5

[126] This example illustrates one embodiment of the present invention in which a formaldehyde-emitting product, in this case a commercially available fiberglass insulation product (duct board) obtained from Knauf Fiberglass, is encased in a substantially air-tight package with a substrate carrying a formaldehyde scavenger composition. The substrate comprises a disposable sodium bisulfite treated blotter paper.

[127] A fresh box of Knauf duct board was obtained directly from Knauf Fiberglass. Four pieces of the duct board measuring 8^"'x 20" were cut and placed inside two Mylar© bags. Two pieces of the duct board were placed into each bag. Blotter papers were placed both outside of and between the pieces of duct board in alternating layers in the bag and then the bags were sealed.

[128] For the control sample, blotter paper was used without any treatment. For the formaldehyde scavenger-treated sample, the sheets of blotter paper were prepared by spraying the paper with a total of approximately 115 grams of a 33.3% sodium bisulfite solution per piece of duct board (for a total of about 230 grams of the 33.3% by weight sodium bisulfite solution onto all of the blotter papers added into the bags). The treated blotter paper was dried in an oven for 4 minutes at 105 ⁰C before it was placed into the bags with the samples.

[ 129] The sheets of the treated blotter paper were placed immediately into the Mylar® bag with the pieces of insulation and the bag was sealed. The samples were allowed to sit in the sealed bags for 72 hours at ambient conditions. Following this, the insulation was removed from the sealed bags and was tested without the scavenger-treated blotter paper in the DMC (Dynamic Micro Chamber) for formaldehyde emissions. Emissions were collected using 20 mis of 0.25N NaOH in the impinger. Air flow into the impinger solution was set at 1.0 liters/minute. Air flow rate inside the DMC was set at 1.5 liters/minute. Impinger solutions were tested for formaldehyde emissions using the standard chromotropic acid method.

[130] The product formaldehyde emissions were measured immediately upon removal from the Mylar® bag. The control sample exhibited a formaldehyde emission level of 49.8 ppb; while the formaldehyde scavenger-treated sample exhibited a formaldehyde emission level of 12.3 ppb, a reduction of over 75%.

EXAMPLE 6

[131] This example illustrates another embodiment of the present invention in which a formaldehyde-emitting product, in this case a commercially available R- 19 imfaced fiberglass insulation blanket product obtained from Knauf Fiberglass, is encased in a substantially air-tight package with a substrate carrying a formaldehyde scavenger composition. The substrate comprises a disposable sodium bisulfite treated blotter paper.

[132] A fresh bag of Knauf R- 19 insulation, unfaced, Product Code 1825, marked 509 6 B62 was obtained directly from Knauf Fiberglass. An entire batt was rolled as tightly as possible and put into a Mylar® bag that was approximately 23" wide x 30" high. Two pieces (sheets) of 12"x 12" blotter paper were placed inside the bag. The sheets of paper were placed between the outside of the rolled batt and the inside wall of the Mylar® bag and then the bags were sealed.

[133] For the control sample, sheets of the blotter paper were used without any treatment. For the formaldehyde scavenger-treated sample, the sheets of blotter paper were prepared by spraying with 39.2 grams and 36.1 grams respectively of a 33.3% sodium bisulfite solution. Each of the treated paper sheets were dried in an oven for 4 minutes at 105 ⁰C. The treated papers were placed immediately into the Mylar® bag with the compressed fiberglass insulation batt and the bag was sealed.

[134] The samples were retained in the sealed bags for 72 hours at ambient conditions. The insulation was removed from the sealed back and then promptly tested - without the scavenger- treated paper - in the DMC (Dynamic Micro Chamber) for formaldehyde emissions. Emissions were collected using 20 mis of 0.25N NaOH in the impinger. Air flow into the impinger solution was set at 1.0 liters/minute. Air flow rate inside the DMC was set at 1.5 liters/minute. Impinger solutions were tested for formaldehyde emissions using the standard chromotropic acid method.

[135] The product formaldehyde emissions were measured immediately upon removal from the Mylar® bag. The control sample exhibited a formaldehyde emission level of 55.5 ppb; while the formaldehyde scavenger-treated sample exhibited a formaldehyde emission level of 2.2 ppb, a reduction of over 95%.

EXAIVlPLE 7

f 136] This example illustrates an embodiment of the present invention in which a formaldehyde-emitting product, in this case a commercially available blowing wool product (Owens Corning Advanced ThermaCube Plus® blowing wool) is encased in a substantially air-tight container or package with a gaseous formaldehyde scavenger, e.g., sulfur dioxide.

[137] A control sample was prepared by placing 135 grams of the Advanced

ThermaCube Plus® (hereinafter ATC+) blowing wool into a large Ziplock® bag. The bag then was sealed tightly,

[138] To prepare a treated sample, 135 grams of the ATC+ blowing wool also was placed into a large Ziplock® bag and then SO?, as a gaseous formaldehyde scavenger, was filled into the bag (the intent was to replace all of the gas in the bag with SO2) and the bag was sealed tightly.

[139] The product formaldehyde emissions were measured in the DMC (Dynamic

Micro Chamber) using the Ceq test three days after the samples were prepared. A DMC is described in Georgia-Pacific Resins, Inc. U.S. Patents 5,286,363 and 5,395,494.

[140] The ATC+ blowing wool samples were removed from the respective bags and placed into a wire basket that was approximately 14" x 21." The basket had a tinfoil bottom to prevent the ATC+ blowing wool from falling through the holes in the basket. The basket was made from wire mesh with holes that were approximately 1/2" wide. The basket is placed into the DMC and the Ceq test is conducted. In the Ceq test, air is circulated inside the chamber for 30 minutes with no air flow entering or exiting the chamber. After 30 minutes, the impinger of the device is hooked to the chamber and the impinger is sparged with air from the chamber for 30 minutes at a rate of 1.0 liter per minute. Air exiting the impinger is returned to the DMC, Emissions are collected using 20 mis of 0.25N NaOH in the impinger. Impinger solutions are tested for formaldehyde emissions using the standard chromotropic acid method. The results comparing the level of formaldehyde emission from the control sample to the emission form the treated sample are presented in Table 5.

Table 5 Product Formaldehyde Emissions Results

EXAMPLE 8 To simulate the manufacture of fiberglass insulation, batts were prepared in the laboratory as follows. A roll of 1 inch thick, un-bonded, fiberglass was obtained from Resolute Manufacturing and divided into individual sheets weighing about 30 grams. Individual un-bonded fiberglass sheets were placed in a tray. A formaldehyde-containing binder was placed into a reservoir and air was used to aspirate the binder into a fine mist. The mist was drawn through each individual batt using an air exhaust hood. This technique caused fine binder droplets to be deposited onto and into the batt. Approximately eight grams of binder was deposited onto each sample of the glass batt. Following binder application, the batts were cured in a forced air oven for two minutes at 425 ⁰F (218 ⁰C) to cure the binder. After curing, one batt was treated with ammonia by breaking ammonia smelling salt inside a Ziplock®-type storage bag which was immediately sealed, the other sample was transferred to another Zip!ock®-type storage bag without any treatment until both sample could be tested using a consistent technique in a dynamic micro chamber (DMC) to test its formaldehyde emission characteristic. [142] The average results reported as the ppb formaldehyde are reported in Table 6 below. As shown, the method of the present invention resulted in a significant reduction in formaldehyde emission compared with the Control Example.

Table 6 Formaldehyde Emission Results

(ppb Formaldehyde)

EXAMPLE 9

[143] This example illustrates another embodiment of the present invention in which a formaldehyde-emitting product, in this case a commercially available blowing wool product (Owens Corning Advanced ThermaCube Plus© blowing wool) is encased in a substantially air-tight container or package with a gaseous formaldehyde scavenger, e.g., sulfur dioxide.

[144] A control sample was prepared by placing 135 grams of the Advanced

ThermaCube Plus® (hereinafter ATC+) blowing wool into a IL nalgene bottle and sealed.

[145] Treated samples were prepared by also putting 135 grams of ATC+ blowing wool into a IL nalgene bottle. Sulfur dioxide (120 cubic centimeters STP) was injected into the bottom of the bottle using a hypodermic needle and the bottle was sealed. Three concentrations of sulfur dioxide were used, pure (100%), 10 % (by volume in nitrogen) and 1 % (by volume in nitrogen).

[146] The product formaldehyde emissions were measured four (4) days later in the DMC (Dynamic Micro Chamber) using the Ceq test. The ATC+ blowing wool samples were removed from the respective bottles and placed into a wire basket that was approximately 14" x 21." The basket had a tinfoil bottom to prevent the ATC+ blowing wool from falling through the holes in the basket. The basket was made from wire mesh with holes that were approximately 1/2" wide. The basket is placed into the DMC and the Ceq test is conducted. In the Ceq test, air is circulated inside the chamber for 30 minutes with no air flow entering or exiting the chamber. After 30 minutes, the impinger of the device is hooked to the chamber and the impinger is sparged with air from the chamber for 30 minutes at a rate of 1.0 liter per minute. Air exiting the impinger is returned to the DMC. Emissions are collected using 20 mis of 0.25N NaOH in the impinger. Impinger solutions are tested for formaldehyde emissions using the standard chromotropic acid method. The results comparing the level of formaldehyde emission from the control sample to the emission form the treated samples are presented in Table 7.

Table 7 Product Formaldehyde Emissions Results

EXAMPLE 10 The procedure of Example 9 was repeated. However, in this case the treated samples were prepared by injecting a gas containing 10% by volume sulfur dioxide in nitrogen into the bottom of the nalgene bottle using a hypodermic needle and the bottle was sealed. Four (4) treated samples were prepared using 5, 10, 20 and 40 cubic centimeters (STP) of the gas for the respective treatments. The DMC Ceq results comparing the level of formaldehyde emission from the control sample to the emission form the treated samples are presented in Table 8. Table 8 Product Formaldehyde Emissions Results

EXAMPLE 11

[148] Four commercial plastic bags of Owens Corning Advanced ThermaCube Plus® loosefill insulation (e.g., blowing wool) were obtained directly from Owens Corning in Fairburn, GA (Product code 295894, Item reference number was Ll 6). Each bag contained approximately 35 pounds of compressed blowing wool product. One bag was retained as a control. The other three bags were treated by injecting gaseous sulfur dioxide into the bags using an apparatus constructed in accordance with Figure 1. The sulfur dioxide was injected into the bags through a needle that pierced the bag wall. The sulfur dioxide injections were conducted in a controlled room which has a volume of 28.32 m³ and an air exchange rate 0.5 air exchanges per hour, i.e., every hour Vz of the volume of air in the room is exchanged.

[149] The first test bag was provided with a single injection of approximately 1 liter (STP) of sulfur dioxide (approximately 2.9 g) with the output of the injection needle located at the center of the bag. The second test bag was injected with approximately 2 liters (STP) of sulfur dioxide (approximately 5.7 g) using two one liter injections spaced equi-distance from the sides of the bag. The third test bag was also injected twice to provide a total of approximately 5 liters (STP) of sulfur dioxide (approximately 14.3 g), using one injection of 2 liters and one injection of 3 liters both positioned at the center of the bag. Immediately after the injections, a commercially available Drager Chip Measurement System (CMS) detector (available from Draeger Safety, Inc.) fitted with an SOi chip designed to measure SO₂ in the 0.4 ppm to 10.0 ppm range was used to measure any SOi in the the control room in the vicinity of the bag treatment assembly. The detector did not measure any sulfur dioxide during the first and second bag filling operations. There was a slight odor of sulfur dioxide following the injection of 5 liters in the third test, but no measurement of the actual concentration was successfully made.

[150J All four bags were then stored under ambient conditions. After eight days, each back was brought individually into the control room for analysis of residual sulfur dioxide and formaldehyde emission testing. The first and third treated bags were opened and the Drager tester was used again to measure SO? in the air in the vicinity of the blowing wool insulation. There was no detectible residue of sulfur dioxide from the first test bag. Multiple measurements were taken with the third test bag. The Drager CMS recorded sulfur dioxide levels in the 0.4 to 2.76 ppm range in connection with the third bag. Samples of the insulation, including a sample from the control bag, were transferred to Nalgene bottles for formaldehyde and corrosion testing. Specifically, about 135 grams of insulation were placed into 1 liter Nalgene bottles.

[151] Product formaldehyde emissions were then measured in the Dynamic Micro

Chamber (DMC) using the equilibrium (Ceq) test protocol. Samples of blowing wool that had been removed from the various bags were individually placed into a wire basket that was approximately 14" x 21" in size. The basket had a foil bottom to prevent the blowing wool sample from falling through the holes in the basket. The basket was made from wire mesh with holes that were approximately 1/2" wide. The basket was placed into the DMC and the test was started. In the Ceq test, air is circulated inside the DMC for 30 minutes with no air flow entering or exiting the chamber. After 30 minutes, an impinger is connected to the DMC and the impinger is sparged with air from the chamber for 30 minutes at a rate of 1.0 liter per minute. Air exiting the impinger is returned to the DMC. Emissions are collected using 20 mis of 3 % NaOH in the impinger.

-SO- Impingcr solutions are tested for formaldehyde emissions using the standard chromotropic acid method.

[152] After testing in the DMC, the samples were stored in the control room and then tested again in the DMC for formaldehyde emissions again using the Ceq test. Results are shown in Table 9 below.

[153] The control sample and the treated samples also were tested for corrosivity to see if any of the sulfur dioxide had been converted to corrosive sulfuric acid. The corrosion test involved placing 50 grams of blowing wool insulation into a plastic container and then inserting the plastic container into a desiccator containing 50 grams water. A cleaned metal coupon was placed directly on top of the insulation. The desiccators were sealed and then stored in an oven for 4 days at 49 ⁰C. Photographs were taken of control samples and the treated samples.

TABLE 9 Product Formaldehyde Emissions Results

• N.D. = Non-Dectectable

[154] Results showed that injecting an amount of sulfur dioxide effective for reducing initial formaldehyde emission in the commercial blowing wool product to a non- detectible level in the equilibrium test procedure did not cause SO₂ to be released either during the injection or later upon opening the bag (amount of SCb was below the 0.4 ppra detection limit of the test detector). Even when the amount of SO was five times higher that that needed to obtain an effective treatment, the amount of SO₂ released during injection and again when bag is opened twaas below the Short Term Exposure Limit (STEL) established for SO₂ of 5 ppm. The samples tested for corrosivity showed that the treated samples were no more corrosive than the untreated control.

The present invention has been described with reference to specific embodiments. However, this application is intended to cover those changes and substitutions that may be made by those skilled in the art without departing from the spirit and the scope of the invention. Unless otherwise specifically indicated, all percentages are by weight. Throughout the specification and in the claims the term "about" is intended to encompass + or - 5%.

Claims

IAVe claim as follows:

1. A process of reducing the level of formaldehyde emission from a fibrous product in which the fibrous product comprises a cured formaldehyde-containing resin binder, the process comprising isolating the fibrous product with a formaldehyde-scavenger such that the formaldehyde- scavenger is in a mass transfer relationship with the fibrous product.

2. The process of claim 1 wherein the formaldehyde scavenger is provided as a formaldehyde scavenger composition carried by a substrate.

3. The process of claim 2 wherein the formaldehyde scavenger composition comprises a formaldehyde scavenger selected from the group consisting of tetraethylεne pentamine, sodium bisulfite, and sodium metabisulfite.

4. The process of claim 2 wherein the substrate carrying the formaldehyde scavenger composition is selected from the group consisting of a paper saturated with a formaldehyde scavenger composition, a vial containing a formaldehyde scavenging composition, a porous packet containing a formaldehyde scavenging composition, a plastic film coated with a formaldehyde scavenging composition and a metal foil coated with a formaldehyde scavenging composition.

5. The process of claims 1 wherein the fibrous mat is isolated by encasing the fibrous mat in a substantially airtight package.

6. A process of producing a fibrous mat wherein the fibrous mat comprises a cured formaldehyde-containing resin binder and the fibrous mat has a backing sheet, the process comprising applying a formaldehyde- scavenger composition onto the backing sheet so that the formaldehyde- scavenger composition is in a mass transfer relationship to the fibrous mat.

7. The process of claim 6 wherein the formaldehyde scavenger composition is applied to the backing sheet as a liquid.

8. The process of claim 7 wherein the liquid is an aqueous mixture of a formaldehyde- scavenger.

9. The process of claim 6 wherein a neat form of the formaldehyde scavenger is applied to the backing sheet,

10. The process of claim 9 wherein the formaldehyde scavenger composition comprises solid particles of a formaldehyde scavenger.

11. The process of claim 10 wherein the formaldehyde scavenger is loaded onto solid particles of an inert carrier.

12. The process of claim 6 wherein the formaldehyde scavenger composition comprises a formaldehyde scavenger selected from the group consisting of urea, low mole ratio melamine resins, sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium sulfamate, ammonium sulfamate, an acid aniline salt, ammonium bisulfite, ammonium sulfite, methane sulfonamide, succinimide, resorcinol, polyacrylamide, acrylamide, methacrylamide, melamine, diethylene triamine and its salts, triethylene tetraamine and its salts, tetraethylene pentamine and its salts, biuret, triuret, biurea, polyurea, aromatic amines, aliphatic amines, ammonia, polyamidoamines, ammonium bicarbonate, ammonium carbonate, polyethyfeneamines, polyamines, dicyandiamide, a sodium salt of taurine, sulfanilic acid, sulfur compounds with valence state other than +6, ammonium sulfite, disodium salt of glutamic acid, an amino acid, a protein, an aromatic amino acid, an aminopolysaccharide, p-amino benzoic acid, thiourea, guanadine, zeolites and permanganate.

13. The process of claim 6 wherein the formaldehyde scavenger is selected from the group consisting of tetraethylene pentamine, sodium bisulfite, and sodium metabisulfite.

14. The process of claim 6 wherein the formaldehyde scavenger is sodium bisulfite.

15. The process of claim 6 wherein the formaldehyde scavenger composition comprises between 0.1 and 200 % by weight of the backing sheet.

16. A fibrous mat produced by the process of claim 6, 7, 8, 9, 10. 11. 12, 13, 14 or 15.

17. The process of claim 6 further comprising isolating the fibrous mat with the backing sheet in a hermetically sealed enclosure.

18. A fibrous mat having fibers bonded to one another with a binder comprising a cured formaldehyde-containing resin and having a backing sheet adjacent the fibrous mat, wherein the backing sheet carries a formaldehyde scavenger composition in a mass transfer relationship to the fibrous mat and in an amount sufficient to reduce formaldehyde emissions from the fibrous mat.

19. The fibrous mat of claim 18 wherein the formaldehyde scavenger composition comprises a formaldehyde scavenger selected from the group consisting of urea, low mole ratio melamine resins, sodium bisulfite, sodium metabisulfite, sodium sulfite, sodium sulfamate, ammonium sulfamate, an acid aniline salt, ammonium bisulfite, ammonium sulfite, methane sulfonamide, succinimide, resorcinol, polyacryl amide, acrylamide, me thacryl amide, melamine, diethylene triamine and its salts, triethylene tetraamine and its salts, tetraethylene pentamine and its salts, biuret, triuret, biurea, polyurea, aromatic amines, aliphatic amines, ammonia, polyamidoamines, ammonium bicarbonate, ammonium carbonate, polyethyleneamines, polyamines, dicyandiamide, a sodium salt of taurine, sulfanilic acid, sulfur compounds with vaience state other than +6, ammonium sulfite, disodium salt of glutamic acid, an amino acid, a protein, an aromatic amino acid, an aminopolysaccharide, p-amino benzoic acid, thiourea, guanadine, zeolites and permanganate.

20. The fibrous mat of claim 18 wherein the formaldehyde scavenger is selected from the group consisting of tetraethylene pentamine, sodium bisulfite, and sodium metabisulfite.

21. The fibrous mat of claim 18 wherein the formaldehyde scavenger is sodium bisulfite.

22. The fibrous mat of claim 21 wherein the formaldehyde scavenger composition is present as solid particles.

23. The fibrous mat of claim 22 wherein the solid particles comprise the formaldehyde scavenger composition loaded onto an inter carrier.

24. The fibrous mat of claim 18 wherein the formaldehyde scavenger composition comprises between 0.1 and 200 % by weight of the backing sheet.

25. The fibrous mat of claim 18 wherein the backing sheet comprises a sheet of paper.

26. The fibrous mat of claim 18 wherein the backing sheet comprises a film of plastic.

27. The fibrous mat of claim 18 wherein the backing sheet comprises a metal foil.

28. The fibrous mat of claim 18 wherein the backing sheet comprises a glass mat.

29. The fibrous mat of claim 18 wherein the backing sheet comprises a fabric.

30. A backing sheet for a fiberglass insulation product comprising a substrate in sheet form carrying a formaldehyde scavenger composition.

31. The backing sheet of claim 30 wherein the formaldehyde scavenger composition comprises a formaldehyde scavenger selected from the group consisting of urea, low mole ratio melamine resins, sodium bisulfite, sodium metabi sulfite, sodium sulfite. sodium sulfamate, ammonium sulfamate, an acid aniline salt, ammonium bisulfite, ammonium bisufite, methane sulfonamide, succinimide, resorcinol, pol y aery 1 amide, acrylamide, methacrylamide, melamine, diethylene triamine and its salts, triethylene tetraamine and its salts, tetraethylene pentamine and its salts, biuret, triuret, biurea, polyurea, aromatic amines, aliphatic amines, ammonia, polyamidoamines, ammonium bicarbonate, ammonium carbonate, polyethyleneamines, polyamines, dicyandiamide, a sodium salt of taurine, sulfanilic acid, sulfur compounds with valence state other than +6, ammonium sulfite, disodium salt of glutamic acid, an amino acid, a protein, an aromatic amino acid, an aminopolysaccharide, p-amino benzoic acid, thiourea, guanadine, zeolites and permanganate.

32. The backing sheet of claim 31 wherein the formaldehyde scavenger is selected from the group consisting of tetraethylene pentamine, sodium bisulfite, and sodium metabisulfite.

33. The backing sheet of ciaim 31 wherein the formaldehyde scavenger is sodium bisulfite.

34. The backing sheet of claim 30 wherein the formaldehyde scavenger composition comprises between 0.1 and 200 % by weight of the backing sheet.

35. The backing sheet of claim 30 wherein the substrate is selected from the group consisting of a sheet of paper, a glass mat, a fabric, a film of plastic, a metal foil and combinations thereof.

36. A process of reducing the level of formaldehyde emission from a fibrous product according to claim 1 wherein the fibrous product is isolated in an enclosed space, a gaseous formaldehyde scavenger is introduced into the space and the gaseous scavenger is maintained in the space for a time sufficient to reduce the level of formaldehyde emission.

37. The method of claim 36 wherein the fibrous product is wrapped with a film of material to produce the enclosed space.

38. The method of claim 36 wherein the fibrous product is placed into a bag and the bag is then sealed to produce the enclosed space.

39. The method of claim 36. 37, or 38 wherein the gaseous formaldehyde scavenger is selected from the group consisting of ammonia and sulfur dioxide.

40. The method of claim 38 wherein the gaseous formaldehyde scavenger is sulfur dioxide.

41. The method of claim 38 wherein the bag comprises a plastic.

42. The method of claim 40 wherein the bag comprises a plastic.

43. The method of claim 37 wherein the film of material comprises a plastic.

44. The method of claim 36 wherein an amount of the gaseous formaldehyde scavenger between 0.03 g to 10.0 g per IKg of the fibrous product is introduced into the enclosed space.

45. The method of claim 42 wherein an amount of the gaseous formaldehyde scavenger between 0.03 g to 10.0 g per IKg of the fibrous product is introduced into the enclosed space.

46. The method of claim 36 wherein an amount of the gaseous formaldehyde scavenger between 0.06 g to 5.0 g per IKg of the fibrous product is introduced into the enclosed space.

47. The method of claim 42 wherein an amount of the gaseous formaldehyde scavenger between 0.06 g to 5.0 g per IKg of the fibrous product is introduced into the enclosed space.

48. A fibrous mat produced by the method of claim 36, 37. 38, 39, 40, 41, 42. 43, 44, 45, 46. or 47.