WO2002036516A2

WO2002036516A2 - Window glazing composition and use thereof

Info

Publication number: WO2002036516A2
Application number: PCT/US2001/046594
Authority: WO
Inventors: James W. Nowicki; Shawn G. Ryan; Ju-Ming Hung; Mike Colucci
Original assignee: National Starch And Chemical Investment Holding Corporation
Priority date: 2000-10-28
Filing date: 2001-10-26
Publication date: 2002-05-10
Also published as: WO2002036516A3; AU2002236564A1

Abstract

A reactive hot melt adhesive is used as a backbedding or glazing compound in the construction of various types of windows.

Description

WINDOW GLAZING COMPOSITION AND USE THEREOF

FIELD OF THE INVENTION

The invention relates to the fenestration field. More specifically, the invention relates to the use of adhesive compositions in window glazing operations. The invention also relates to articles, in particular, residential and commercial windows comprising such glazing compositions.

BACKGROUND OF THE INVENTION Current methods for structural window glazing are extremely labor intensive. Following positioning of the window pane within the window frame, a glazing compound must be applied. The glazed window must be allowed to cure in a horizontal position. No shipment can occur until cure is substantially complete. Alternatively, a permanent or temporary tacking strip may be used to hold the window pane within the frame during cure in a vertical position and/or during shipment prior to cure. Such case, however, requires an extra step and increased costs in terms of material and labor, and may even require the retailer or end user to remove temporary structural elements.

In addition to cost of materials and labor, storage costs are increased, particularly if windows in a variety of sizes and types are to be ready for immediate shipment upon receipt of a customer order. There is thus a need in the art for a glazing composition and methods of using the composition to improve productivity, to keep production costs low and to enable the production and shipment of a variety of window types on short notice. SUMMARY OF THE INVENTION The invention provides a method of preparing a finished window. The method of the invention lowers costs by eliminating labor, enables reduction of inventory, allows shipment to occur shortly after the manufacture thereof and can be adapted for automated production.

One aspect of the invention is directed to a method of making a window comprising obtaining a peripheral frame-like member which defines a central opening and a step-like ledge surface adjacent to said central opening for receiving and retaining a glass pane, positioning for retention within said central opening a glass pane, said glass pane being supported within said central opening by the step-like ledge surface and securing the glass pane to the frame-like member and/or the step-like ledge thereof by applying a glazing compound comprising a reactive hot melt adhesive. In one embodiment, the window is prepared by melting a reactive polyurethane adhesive in a heated reservoir; pumping the adhesive from the heated reservoir into a heated foaming device; foaming the adhesive by injecting therein an effective amount of an anhydrous gas; discharging a portion of the foamed adhesive through an orifice onto a substrate to be bonded, i.e., the frame-like member and/or the step-like ledge thereof and the glass pane

Yet another aspect of the invention is directed to a window comprising a reactive hot melt adhesive. In one embodiment the window comprises a peripheral frame-like member which defines a central opening and a step-like ledge surface adjacent to said central opening, a glass pane positioned within said central opening, said glass pane being supported within said central opening by the step-like ledge surface and secured to the frame-like member and/or the step-like ledge thereof by a glazing compound comprising a reactive hot melt adhesive. In a preferred embodiment, the reactive hot melt is a foamed reactive hot melt adhesive.

DETAILED DESCRIPTION OF THE INVENTION

The disclosures of all references cited herein are incorporated in their entireties by reference.

A fenestration is an opening in a building, i.e., in a wall or roof. A fenestration product is a door, window or skylight assembly that fits in a building opening and is used to close the opening. In such products it is common to provide a sash which frames or retains a transparent pane, usually glass. The sash can be thought of as a peripheral frame and can be movable or stationary relative to a building frame mounted to a building and within which the sash is carried. In some situations there is no sash and the pane is set directly in the frame for the product. This is sometimes referred to as a direct set.

The pane is usually transparent and may be a single pane. However, due to temperature differentials between the external environment and the internal environment heat loses often occur. For example, in the winter the outside is cold relative to the inside, which is usually heated, and in the summer the inside is air conditioned and is cooler than the outside. In order to minimize the heat loss and/or condensation problems, an insulating glass unit is often used, wherein multiple spaced but parallel panes are sealed together to form a subassembly which is installed in the sash or frame. The space between the glass panes is insulated, sometimes filled with a gas, and separates the inside and outside panes. This spacing or insulation minimizes condensation and heat loss. Window as used herein refers to windows intended for installation into new construction, as well as replacement windows and includes, without limitation, single hung windows, double hung windows, sliding windows, pivoting windows, casement windows, patio doors, picture windows, bay windows and storm windows. Included are windows designed for use in residential dwellings, i.e., single and multiply family homes, light commercial (e.g., apartment) buildings, and commercial buildings. Single pane as well as insulating glass units are contemplated for use in the practice of the invention. The windows made in accordance with the invention may be of any desired shape such as square, rectangular, circular, semicircular or the like, and may be of any desired size.

The invention provides an improved fenestration construction which comprises a peripheral frame-like member which defines a central opening and a step-like ledge surface or "bite" adjacent to said central opening for receiving and retaining a glass pane positioned for retention within said central opening and a glazing compound which secures the pane within said frame-like member.

The term glazing compound is used herein to refer to what is conventionally referred to in the art as a backbedding compound or glazing sealant, and functions to hold a glass window pane securely in the window frame or sash.

Compositions contemplated for use as glazing compounds in the practice of the invention include liquid polyurethanes, thermoplastic adhesives, polyurethane rubbers, silicone rubbers, reactive silicone hot melts and reactive polyurethane hot melts, and, in particular, foamed formulations thereof. In preferred embodiments of the invention, the glazing compound is a moisture curable reactive hot melt adhesive. While silicon and polyurethane hot melt adhesives and foamed moisture curable silicon and polyurethane hot melt adhesives are preferred, in terms of strength, cost and processing time, the use of a foamed polyurethane reactive hot melt adhesive is a particularly preferred embodiment. Reactive hot melt adhesive compositions may be foamed using conventional chemical or mechanical foaming techniques, with or without the use of accelerators using procedures such as are disclosed in U.S. Patent Nos. 4,059,466; 4,059,714; 4,156,754; 4,259,402; 4,679,710; 4,601 ,427; 4,535,919; 4,405,063; 4,371 ,096; 4,264,214; and 4,200,207. A typical process for foaming comprises melting a reactive polyurethane adhesive containing in a heated reservoir; pumping the adhesive from the heated reservoir into a heated melt foaming device; foaming the adhesive by injecting therein an effective amount of an anhydrous gas; discharging a portion of the foamed adhesive through an orifice onto a substrate to be bonded. Foaming units which may be used to practice the invention are commercially available, e.g., Nordsons Foam Mix™ and Nordson Foam Melt™ .

More specifically, the hot melt adhesive is charged into the melting reservoir of the foam melting device and heated to from about 150° to about 350° F in order to keep the adhesive molten. The molten adhesive is then pumped from the melting reservoir into the foaming unit where the material is also maintained at a temperature of 150° to 350° F, preferably 200° to 300° F. While in the foaming unit, the adhesive is passed through a foaming pump where inert gas is injected at a pressure between 1 and 15 psi, preferably 3 to 8 psi, in an amount and at a rate sufficient to reduce the adhesive density by about 10% to about 70%, preferably about 25% to about 75%, The foamed adhesive is then extruded from the foaming unit through a heated dispenser orifice where it is applied to the substrate to be bonded.

Methods for applying the glazing composition are known in the art and include, but are not limited to, roll coating, spraying, and extrusion. The composition may be applied manually, with the use of manually operated dispensing equipment or with the use of automatic dispensing equipment. The use of automatic dispensing equipment is particularly preferred.

While a preferred embodiment comprises the glazing of glass window pane into a frame or sash made of vinyl, aluminum, wood and fiberglass composite sashes and the like are also encompassed by the invention.

One skilled in the art can vary the amount of foam to suit the desired strength. By modifying the amount of foam, the pane may be permanently or removeably secured within the opening. Typically, in the practice of the invention, the foam is applied at from about 0.1 grams per linear foot to about 4 grams per linear foot, preferably from about 0.5 to about 3 grams per linear foot, more preferably at least about 2 grams per linear foot. Bead sizes of from about 1/32 inch up to about 1/2 inch or wider can by used in the practice of the invention. Preferred for use is a bead size of from about 1/16 inch to about 1/4 inch, more preferably a bead size of about 1/8 inch to about 3/16 inch. One skilled in the art can readily determine the most advantageous bead size based on the size of the window and desired characteristics

In the practice of the invention, the glass may be set from the exterior or the building ("exterior glazed") or set from the interior of the building ("interior glazed") While the invention will hereinafter be described in terms of reactive hot melt polyurethane adhesives, it will be understood that the invention is not to be so limited. Polyurethane hot melt adhesives are comprised of isocyanate- terminated polyurethane polymers, often referred to as "prepolymers," that react with surface or ambient moisture in order to chain-extend and form a second polyurethane polymer. Unlike conventional hot melt adhesives, which can be heated to a liquid state and cooled to a solid state repeatedly, a reactive hot melt undergoes an irreversible chemical reaction to a solid "cured" form once dispensed in the presence of ambient moisture. Reactive hot melts are therefore useful in the manufacture of articles which are or may potentially be exposed to high temperatures.

Reactive polyurethane hot melt adhesives of the invention comprise an isocyanate and a polyol

The urethane prepolymers are those conventionally used in the production of polyurethane hot melt adhesive compositions. Any suitable compound which contains two or more isocyanate groups may be used for preparing the urethane prepolymers. Typically from about 5 to about 75 parts by weight of an isocyanate is used.

Organic polyisocyanate which may be used to practice the invention include alkylene diisocyanates, cycloalkylene diisocyanates, aromatic diisocyanates and aliphatic-aromatic diisocyanates. Spcific examples of suitable isocyanate-containing compounds include, but are not limited to, ethylene diisocyanate, ethylidene diisocyanate, propylene diisocyanate, butylene diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, cyclopentylene-1 ,3-diisocyanate, cyclo- hexylene-1 ,4-diisocyanate, cyclohexylene-1 ,2-diisocyanate, 4,4'- diphenylmethane diisocyanate, 2,2-diphenylpropane-4,4'-diisocyanate, xylylene diisocyanate, 1 ,4-naphthylene diisocyanate, 1 ,5-naphthylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, diphenyl- 4,4'-diisocyanate, azobenzene-4,4'-diisocyanate, diphenylsulphone-4,4'- diisocyanate, 2,4-tolylene diisocyanate, dichlorohexa-methylene diisocyanate, furfurylidene diisocyanate, 1-chlorobenzene-2,4-diisocyanate, 4,4',4"-triisocyanatotriphenylmethane, 1 ,3,5-triisocyanato-benzene, 2,4,6- triisocyanato-toluene, 4,4'-dimethyldiphenyl-methane-2,2',5,5- tetratetraisocyanate, and the like. While such compounds are commercially available, methods for synthesizing such compounds are well-known in the art. Preferred isocyanate-containing compounds are methylenebisphenyidiisocyanate (MDI), isophoronediisocyanate (IPDI) and toluene diisocyanate (TDI).

Most commonly, the prepolymer is prepared by the condensation polymerization of a polyisocyanate with a polyol, most preferably the polymerization of a diisocyanate with a diol. The polyols used include polyhydroxy ethers (substituted or unsubstituted polyalkylene ether glycols or polyhydroxy polyalkylene ethers), polyhydroxy polyesters, the ethylene or propylene oxide adducts of polyols and the monosubstituted esters of glycerol, as well as mixtures thereof. The polyol is typically used in an amount of between about 1 to about 70 parts by weight. Examples of polyether polyols include a linear and/or branched polyether having plural numbers of ether bondings and at least two hydroxyl groups, and contain substantially no functional group other than the hydroxyl groups. Examples of the polyether polyol may include polyoxyalkylene polyol such as polyethylene glycol, polypropylene glycol, polybutylene glycol and the like. Further, a homopolymer and a copolymer of the polyoxyalkylene polyols may also be employed. Particularly preferable copolymers of the polyoxyalkylene polyols may include an adduct at least one compound selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, 2-ethyIhexanediol-

1.3, glycerin, 1 ,2,6-hexane triol, trimethylol propane, trimethylol ethane, tris(hydroxyphenyl)propane, triethanolamine, triisopropanolamine, ethylenediamine and ethanolamine; with at least one compound selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide.

A number of suitable polyols available commercially. By way of example only, there is mentioned CP4701 (Dow Chemicals), Niax 11-34 (Union Carbide Corp), Desmophen 3900 (Bayer), Propylan M12 (Lankro

Chemicals), Highflex 303 (Daiichi Kogyo Seiyaku K.K.) and Daltocel T 32-75 (ICI). "Polymer polyols" are also suitable, i.e. graft polyols containing a proportion of a vinyl monomer, polymerised in situ, e.g., Niax 34-28.

Polyester polyols are formed from the condensation of one or more polyhydric alcohols having from 2 to 15 carbon atoms with one or more polycarboxylic acids having from 2 to 14 carbon atoms. Examples of suitable polyhydric alcohols include ethylene glycol, propylene glycol such as 1 ,2- propylene glycol and 1 ,3-propylene glycol, glycerol, pentaerythritol, trimethylolpropane, 1 ,4,6-octanetriol, butanediol, pentanediol, hexanediol, dodecanediol, octanediol, chloropentanediol, glycerol monallyl ether, glycerol monoethyl ether, diethylene glycol, 2-ethylhexanediol-1 ,4, cyclohexanediol-

1.4, 1,2,6-hexanetriol, 1 ,3,5-hexanetriol, 1,3-bis-(2-hydroxyethoxy)propane and the like. Examples of polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, maleic acid, dodecylmaleic acid, octadecenylmaleic acid, fumaric acid, aconitic acid, trimellitic acid, tricarballylic acid, 3,3'-thiodipropionic acid, succinic acid, adipic acid, malonic acid, glutaric acid, pimelic acid, sebacic acid, cyclohexane-1 ,2- dicarboxylic acid, 1 ,4-cyclohexadiene-1 ,2-dicarboxylic acid, 3-methyI-3,5- cyclohexadiene-1 ,2-dicarboxylic acid and the corresponding acid anhydrides, acid chlorides and acid esters such as phthalic anhydride, phthaloyl chloride and the dimethyl ester of phthalic acid. Preferred polycarboxylic acids are the aliphatic and cycloaliphatic dicarboxylic acids containing no more than 14 carbon atoms and the aromatic dicarboxylic acids containing no more than 14 atoms.

In addition, the urethane prepolymers may be prepared by the reaction of a polyisocyanate with a polyamino or a polymercapto-containing compound such as diamino polypropylene glycol or diamino polyethylene glycol or polythioethers such as the condensation products of thiodiglycol either alone or in combination with other glycols such as ethylene glycol, 1 ,2- propylene glycol or with other polyhydroxy compounds disclosed above. In accordance with one embodiment of the invention, the hydroxyl containing acrylic polymer may function as the polyol component, in which case, no additional polyol need be added to the reaction.

Further, small amounts of low molecular weight dihydroxy, diamino, or amino hydroxy compounds may be used such as saturated and unsaturated glycols, e.g., ethylene glycol or condensates thereof such as diethylene glycol, triethylene glycol, and the like; ethylene diamine, hexamethylene diamine and the like; ethanolamine, propanolamine, N- methyidiethanolamine and the like.

It has been found that the performance of reactive hot melt adhesives for most applications may be substantially improved by the incorporation of acrylic polymers into conventional polyurethane adhesives, as describe in U.S. Patent No. 5,021 ,507 and U.S. Patent No. 5,866,656. In a preferred embodiment of the invention, the urethane is modified by the incorporation of acrylic resins, in particular reactive hydroxy-containing and non-reactive acrylic copolymers. Preferably between about 0 to about 40% by weight of the hydroxylated and or non-hydroxylated acrylic polymer is present in the in the adhesive composition. Virtually any ethylenically unsaturated monomer containing hydroxyl functionality greater than one may be utilized in the compositions of the present invention. Most commonly employed are hydroxyl substituted C1 to C12 esters of acrylic and methacrylic acids including, but not limited to hydroxyl substituted methyl acrylate, ethyl acrylate, n-butyl acrylate, 2- ethylhexyl acrylate, isobutyl acrylate, n-propyl or iso-propyl acrylate or the corresponding methacrylates. Mixtures of compatible (meth)acrylate monomers may also be used. Additional monomers that may be used include the hydroxyl substituted vinyl esters (vinyl acetate and vinyl propionate), vinyl ethers, fumarates, maleates, styrene, acrylonitrile, etc. as well as comonomers thereof.

If used as monomers, these monomers are blended with other copolymerizable comonomers as formulated so as to have a wide range of Tg values, as between about -48° C and 105° C, preferably 15° C to 85° C. Suitable comonomers include the C1 to C12 esters of acrylic and methacrylic acids including, but not limited to methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, n-propyl or iso-propyl acrylate or the corresponding methacrylates. Mixtures of compatible (meth)acrylate monomers may also be used. Additional monomers that may be used include the vinyl esters (vinyl acetate and vinyl propionate), vinyl ethers, fumarates, maleates, styrene, acrylonitrile, ethylene, etc. as well as comonomers thereof. The hydroxyl containing monomers may be the same or different from the monomers used in the remainder of the acrylic polymerization. The particular monomers selected will depend, in large part, upon the end use for which the adhesives are intended. Thus, adhesives to be used in pressure sensitive applications or in applications wherein adhesion to metal is required will be selected to obtain a lower Tg polymer than may be desired in non- pressure sensitive applications or those involving more easily bonded substrates.

When the adhesive is to be prepared utilizing monomeric materials, the respective monomers may be added to the polyols and polymerized therein prior to formation of the prepolymer or may be added to the already formed prepolymer and the acrylic polymerization subsequently performed. In the case of polyamino or polymercapto containing prepolymers, in-situ vinylic polymerization must be performed only in the pre-formed prepolymer. The hydroxyl containing ethylenically unsaturated monomer is polymerized using conventional free radical polymerization procedures to a relatively low molecular weight. For purposes of clarification herein, by "low molecular weight" we mean number average molecular weights in the range of approximately 4,000 to 15,000, preferably to 12,000. Molecular weight distribution is characterized by Gel Permeation Chromatography using a PL Gel, Mixed 10 micron column, a Shimadzu Model RID 6A Detector with a tetrahydrofuran carrier solvent at a flow rate of 1 milliliter per minute. The low molecular weight is obtained by careful monitoring and controlling the reaction conditions and, generally, by carrying out the reaction in the presence of a chain transfer agent such as dodecyl mercaptan. Subsequent to the polymerization of the ethylenically unsaturated monomer(s), the polyisocyanate and any additional ingredients required for the urethane prepolymer forming reaction are added and that reaction is carried out using conventional condensation polymerization procedures. In this manner, the resultant isocyanate terminated urethane prepolymer forms the reactive curing hot melt adhesive described above which contains about 10 to 70% of the urethane prepolymer and 30 to 90% of the low molecular weight hydroxyl containing polymer.

It is also possible to polymerize the low molecular weight polymer in the presence of the already formed isocyanate terminated urethane prepolymer. This method has the drawback of subjecting the prepolymer to unnecessary heating during the acrylic polymerization, heating that might result in branching, viscosity increase, depletion of needed isocyanate groups and possible gellation. Although these disadvantages are subject to control, more stringent control of conditions are required as compared to polymerization in the non-isocyanate functional urethane components. When the reaction is run in the polyol or other non-isocyanate containing component, there is also the advantage of lower reaction viscosities and reduced exposure to isocyanate vapors because of the lesser amount of heating required.

Optionally, the hydroxyl containing functionality may be introduced into the adhesive in the form of pre-polymerized low molecular weight hydroxyl containing polymers. In the latter case, typical polymers include hydroxyl substituted butyl acrylate, hydroxylated butyl acrylate/methyl methacrylate copolymers, hydroxylated ethyl acrylate/methyl methacrylate copolymers, and the like, the polymers having a number average molecular weight of 4,000 to 12,000 and a hydroxyl number of 5 to 15. If used in the form of low molecular weight polymers, the polymers may be blended with the polyol prior to reaction thereof with the isocyanate or they may be added directly to the isocyanate terminated prepolymer.

Preferred adhesives of the invention typically comprise from about 5 to about 50 parts by weight of an isocyante, from about 1 to about 70 parts by weight of a polyol, from about 0 to about 40 parts by weight of an acrylic copolymer and, as a fire retardant component. The polyol may be a polyester polyol, a polyether polyol or a combination thereof.

While the adhesives may be used directly as described above, if desired the adhesives of the present invention may also be formulated with conventional additives which are compatible with the composition. Such additives include plasticizers, compatible tackifiers, catalysts, fillers, anti- oxidants, pigments, adhesion promotors, stabilizers and the like.

Conventional additives which are compatible with a composition according to this invention may simply be determined by combining a potential additive with the composition and determining if they are compatible. An additive is compatible if it is homogenous within the product.

The reactive hot melt adhesives of the invention may also contain flame retardant components. Fire retardant additives known in the art for imparting flame resistance to polyurethane compositions may be added. Such compounds include inorganic compounds such as a boron compound, aluminum hydroxide, antimony trioxide and the like, and other halogen compounds including halogen-containing phosphate compounds such as tris(chloroethyl)phosphate, tris(2,3-dichloropropyl)-phosphate, and the like.

These and other flame retarding compositions are described in U.S. Patent Nos. 3,773,695 4,266,042, 4,585,806, 4,587,273 and 4849467, and

European Patent No. 0 587 942. In a preferred embodiment, ethylenebistetrabromophthalimide and/or tris(2,3-dibromopropyl)- isocyanurate is added as a prime flame retardant component. The ethylenebistetrabromophthalimide and/or tris(2,3-dibromopropyl)isocyanurate may be used with or without other flame retardants. The composition may further comprise a chlorinated paraffin and/or an aryl phosphate ester as a further flame retardant component. The optional chlorinated paraffin imparts flame retardancy as well as performing as a viscosity modifier. The aryl phosphate ester further imparts improved adhesion to the substrates. The flame retardant polyurethane-based reactive hot melt adhesives when used in the practice of the invention gives excellent flame retardancy while maintaining the targeted properties of the base polymer, such as good green strength, controlled setting speed and good thermal stability at elevated temperatures.

This invention also provides a method for bonding articles together which comprises applying the subject reactive hot melt adhesive composition in a liquid melt form to a first article, bringing a second article in contact with the composition applied to the first article, and subjecting the applied composition to conditions which will allow the composition to cool and cure to a composition having an irreversible solid form, said conditions comprising moisture. The composition is typically distributed and stored in its solid form. The composition should be stored in the absence of moisture. When the composition is ready for use, the solid is heated and melted prior to application. Thus, this invention includes reactive polyurethane hot melt adhesive compositions in both its solid form, as it is typically to be stored and distributed, and its liquid form, after it has been melted, just prior to its application.

After application, to adhere articles together, the reactive hot melt adhesive composition is subjected to conditions which will allow it to solidify and cure to a composition which has an irreversible solid form. Solidification (setting) occurs when the liquid melt is subjected to room temperature. Curing, i.e. chain extending, to a composition which has a irreversible solid form, takes place in the presence of ambient moisture. As used herein, "irreversible solid form" means a solid form comprising polyurethane polymers extended from the aforementioned polyurethane prepolymers. The composition having the irreversible solid form typically can withstand temperatures of up to 150 °C. Using ethylenebistetrabromophthalimide as a flame retardant, the thermal stability of the irreversible solid can be improved as evidenced by thermogravimetric analysis.

Many modifications and variations of this invention can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. The specific embodiments described herein are offered by way of example only, and the invention is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A method of making a window comprising obtaining a peripheral frame-like member which defines a central opening and a step-like ledge surface adjacent to said central opening for receiving and retaining a glass pane, positioning for retention within said central opening a glass pane, said glass pane being supported within said central opening by the step-like ledge surface and securing the glass pane to the frame-like member and/or the steplike ledge thereof by applying a glazing compound comprising a reactive hot melt adhesive.

2. The method of claim 1 wherein the reactive hot melt is a silicone reactive hot melt.

3. The method of claim 1 wherein the reactive hot melt is a polyurethane reactive hot melt.

4. The method of claim 1 wherein the reactive hot melt is a foamed silicone reactive hot melt.

5. The method of claim 1 wherein the reactive hot melt is a foamed polyurethane reactive hot melt.

6. A window comprising a reactive hot melt adhesive.

7. A window comprising a peripheral frame-like member which defines a central opening and a step-like ledge surface adjacent to said central opening, a glass pane positioned within said central opening, said glass pane being supported within said central opening by the step-like ledge surface and secured to the frame-like member and/or the step-like ledge thereof by a glazing compound comprising a reactive hot melt adhesive.

8. The window of claim 7 wherein the reactive hot melt is a silicone reactive hot melt.

9. The window of claim 7 wherein the reactive hot melt is a polyurethane reactive hot melt.

10. The window of claim 7 wherein the reactive hot melt is a foamed silicone reactive hot melt.

11. The window of ciaim 7 wherein the reactive hot melt is a foamed polyurethane reactive hot melt.

12. The window of claim 7 wherein the frame-like member is vinyl, aluminum, wood or fiberglass composite.