ENVELOPE OR MAILER HAVING A COPLANAR WINDOW

Abstract: A mailing envelope (4) having a transparent or translucent coplanar window (2) comprising a first sheet (1) having a window (2) cutout with edges encompassing the cutout, forming the major portion of the mailing envelope (4), and a second sheet (3) having edges coextensive with and bonded to the edges of the window (2) cutout in the first sheet (1), forming the window (2).

Description: ENVELOPE OR MAILER HAVING A COPLANAR WINDOW Background of the Invention The present invention relates to enclosures containing printed information with a recipient's address visible from the outside of the enclosure, suitable for mailing. Envelopes comprise traditional such enclosures. In recent times computerized mass mailing systems have used mailers, which are business form intermediates imprinted with individualized information, including recipient's name and address. After individualized printing, these intermediates are then converted to ready-to-mail configuration by folding and/or sealing. Specifically, this invention relates to envelopes and mailers having a cutout opening covered by a transparent window through which the recipient's name and address are visible. More specifically, this invention relates to envelopes and mailers wherein a transparent window covering is co-extensive with the cutout and is coplanar with the sheet material forming the envelope or mailer. Envelopes and mailers with cutout windows are well known in the art and have been used in the business environment for a long time. Many traditional envelopes and mailers simply have an open window with no transparent covering. Others have a window which is covered by a transparent or translucent patch adhered to the envelope ply by an adhesive. Typical of the patent art disclosing such envelopes and mailers are the following U.S. patents: 4,705,298 4,729,506 4,706,878 4,877,177 5,201,464 5,402,934 5,425,500 5,640,831 A recent patent, U.S. 5,418,205, discloses an envelope or mailer having a coplanar window. This invention provides one means for avoiding problems associated with conventional windows wherein a transparent or translucent patch is adhered by adhesive over an opening cut into the front ply of the envelope or mailer. That invention provides a coplanar window, as does the present invention, and thus avoids the increased thickness in conventional envelopes and mailers where the window patch overlaps the front ply. However, impregnation of paper by a transparentizing agent is very limited in its transparentizing effect. A window created by this means is not really transparent but is only translucent. The ability to read name and address by postal scanners is only marginal. The present invention, on the other hand, provides a fully transparent window, which is a marked improvement over U.S. 5,418,205. The coplanar window of the present invention has no value or benefit over a conventional patch window unless or until automated large quantity mass mailings are considered. It is conceivable that an envelope or mailer with a coplanar window could be made by hand, but there would be no incentive to make one or a few such units by hand. The same is true for the coplanar window disclosed and claimed in U.S. 5,418,205. Although one or a few envelopes or mailers as claimed in that patent could be made by hand, there would be no incentive to do so. The problem solved by coplanar windows does not exist for one or a few units - it exists only when large quantities of mail pieces are processed by automated equipment. For example, stacks of sheets feeding from a hopper in a laser printer, or large quantities of mail passing through a postal mail sorter. Thus the present invention pertains only to high volume mailing systems wherein automated equipment is used for printing, folding, sealing, reading, scanning, sorting, etc. The coplanar feature avoids feeding and transport problems which do not exist in low volume hand operations. Summary of the Invention In all the known patent art and in all known commercial use wherein a patch of see-through material is adhered over a window cutout, the patch is larger than the cutout and the edges of the patch overlap the window ply in the area bordering the cutout. In the present invention, the see-through material covering the window does not overlap the ply from which the cutout is made, but is coplanar with it. In the present invention, the edges of the see-through material abut the edges of the cutout and are adhered to these abutting edges. The improvements provided by the present invention derive from the two novel characteristics of the covered window, namely that the covering is coplanar and that the edges of the cutout are adhered to the edges of the window covering. These characteristics provide solutions to two common problems or limitations associated with automated processing of conventional envelopes and mailers having a patch covering a window. These problems are as follows: 1. Mailer intermediates are manufactured either as single sheets or as a continuous web made up of a series of units separated by perforations. The continuous web is zig zag folded into a pack. The sheets are stacked. In both configurations, the overlapping patch adds thickness to each unit in the area around the cutout. When a continuous web is folded into a pack, or sheets are stacked, the accumulated added thickness causes a distortion of the pack, or stack, causing feeding problems when fed into a printer, such as a laser or ink jet printer, or into folding and sealing equipment. The present invention avoids this problem by providing a window which is coplanar with the envelope ply. The coplanar window does not add thickness around the cutout, thus there is no distortion of the pack or stack. 2. In the conventional envelope and mailer, the patch is glued onto the inside surface of the envelope ply. Generally the adhesive does not extend completely to the edge of the cutout. A common problem in high speed postal sorting equipment is that corners and edges of fast moving mail pieces catch under the edges of window cutouts and cause jam-ups. The result is a serious slowdown in the sorting process. The present invention avoids jam-ups in sorting equipment because there is no free edge in the cutout which can catch corners and edges of other mail pieces. Brief Description of the Drawings Fig. 1 is a perspective view of a typical V-fold mailer intermediate having a conventional window cutout and a see-through patch adhered over the cutout; Fig. 2 is a cross sectional view of a conventional mailer intermediate taken along line a/a in Fig. 1 or along line b b in Fig. 4; Fig. 3 is a cross sectional view of one embodiment of the present invention, showing an envelope ply with a coplanar window; Fig. 4 is a plan view of a conventional envelope having a window cutout and a see-through patch adhered under the cutout; Fig. 5 is a diagrammatic side sectional view of one modular apparatus for manufacturing articles of the present invention at high speeds using a continuous web of window material and using a screen printing process to apply bonding agent; Fig. 6 is a diagrammatic side sectional view of a variation of the apparatus depicted in Fig. 5, showing an apparatus for manufacturing articles of the present invention at high speeds using segments of window material severed from a continuous web and using an intermittent extrusion process to apply bonding agent; Figs. 7a through 7d are fragmentary cross sectional views of the continuous web taken at a sequence of steps in the processes depicted in Figs. 5, 6 and 10; Fig. 8 is a diagrammatic side sectional view of another suitable apparatus for manufacturing articles of the present invention at high speeds; Fig. 9 is a fragmentary cross sectional view of one embodiment of the present invention as produced by the method depicted in Fig. 8; Fig. 10 is a diagrammatic side sectional view of yet another modular apparatus for manufacturing articles of the present invention at high speeds; Fig. 11 is a diagrammatic side sectional view showing a variation of the apparatus depicted in Fig. 10; Fig. 12 is a fragmentary cross sectional view of the embodiment of the invention as produced by the apparatus depicted in Fig. 10; Fig. 13 is a fragmentary cross sectional view of the embodiment of the invention as produced when the apparatus depicted in Fig. 10 is modified by the variation depicted in Fig. l i; Fig. 14 is a fragmentary plan view of an envelope or mailer of this invention showing a see-through window lying in its cutout wherein both cuts are straight and smooth; Fig. 15 is a fragmentary plan view of an envelope or mailer of this invention showing a see-through window lying in its cutout wherein both cuts are serrated; Fig. 16 is a fragmentary cross sectional view of an envelope or mailer of this invention showing bonding agent protruding above the paper surface where the edges of the window and the cutout abut; and Fig. 17 is a fragmentary cross sectional view of the envelope or mailer of Fig. 16 wherein the bonding agent has been compressed so that it does not protrude above the paper surface. Detailed Description of the Embodiments Fig. 1 shows a conventional mailer intermediate 4 having a window 2 cut into the envelope ply 1, and having a transparent or translucent patch 3 adhered over the window. After the mailer intermediate is folded along the fold line 8 and sealed, the name and address 5 are visible through the patch. Fig. 2 shows a fragmentary cross sectional view taken along line a-a in Fig. 1 , or along line b-b in Fig. 4. Adhesive 6 adheres the patch over the cutout. The edge 9 of the cutout is a common source of jam-ups in mail sorting operations. Fig. 4 shows a conventional envelope 7 having a window cutout 2 and a patch 3 adhered under the cutout. Figs. 3, 7d, 9, 12, and 13 show the essential elements of the mailer or envelope window of this invention. The window 22 is coplanar with the front ply 12 of the mailer or envelope. The edges of the window 22 are coextensive with the edges of the cutout in the envelope ply 12 and abut with them. In each of the manufacturing methods and embodiments described herein, the edges of the window are bonded to the edges of the cutout in the front ply of a mailing unit. Preferably the bond extends without interruption along the entire extent of the abutting edges. However, in some cases it may be sufficient to bond only a portion of the abutting edges. Fig. 3 shows bonding agent applied to only one surface of the abutting edges. This invention includes structures having bonding agent applied to either one or both surfaces, and encompasses structures wherein bonding includes the entire extent of the abutting edges as well as to structures having bonding at only a portion thereof. In some cases the window itself may function as the bonding agent. In some cases the bonding agent may be applied only to the thin line where edges abut, and in other cases the bonding agent may extend over the entire window or a portion thereof. It is preferred that bonding agent penetrate to some extent into the envelope ply along the edges of the cutout and overlap to some extent onto the edges of the window to enhance the strength to the bond. Fig. 5 shows a diagrammatic side sectional view of a suitable modular apparatus for manufacturing the windowed envelope or mailer of the invention at economically practical speeds. Paper web 12 and film web 13 advance together from supply rolls (not shown) from the right, and wrap anvil cylinder/vacuum cylinder 16. The film ply and the paper ply are die cut simultaneously by the blades 15 of the rotating cylinder 14. Vacuum segment 17 holds film window 22 in place while the paper chip 20 is removed by chip removal chute 21. Chip removal chute 21 may be operatively connected to a vacuum source to facilitate chip removal. As the paper and film webs advance together past the chip removal chute, the paper web and the window are picked up by the large vacuum cylinder 24 and the unused film web is carried off to the right for disposal. The vacuum segment 17 of cylinder 24 encompasses the majority of its circumference and continues to hold the film window in place within the cutout. Although not shown, a vacuum belt could be used here instead of large vacuum cylinder 24. As the paper web advances, it passes application cylinder 19 where bonding agent is applied to the abutting edges of the film window 22 and the edges of the cutout, while the vacuum cylinder continues to hold the window in place. Application cylinder 19 is shown here as a rotary screen printing module but could be a flexographic or gravure apparatus. As the web is carried by vacuum cylinder 24, it passes through curing module 26 where it is exposed to high intensity energy from energy sources 27, causing the bonding agent to solidify, dry, fuse or set, depending on the kind of bonding agent used. The applied energy may be heat for drying water-based or solvent based adhesives, radiant energy for crosslinking polymerizable materials, heat for fusing a powder, or whatever form of energy is appropriate to the particular bonding agent being used. Web speed, energy input, and cylinder circumference are all balanced so that bonding agent 23 is cured, set or dried when it reaches idler 28, where the finished web is carried off to a rewind station or to other equipment for further processing into envelopes or mailers. Vacuum cylinders are shown in Figs. 5 and 6 because they are well known in certain industries for their capability of carrying webs of sheet material. It is also known to use vacuum belts instead of or in conjunction with vacuum cylinders. These perform a similar function but are not as limited in distance and path over which they can carry a web. A vacuum belt is conventionally a continuous loop stretched over at least two cylinders. The belt is perforated by holes distributed over at least a portion of its area and at least a portion of its length and width is spanned by a vacuum chamber (see Fig. 10). When such a vacuum belt carries a web of sheet material, the differential in pressure between the air above the web and the air in the chamber causes the web to adhere to the belt. Fig. 6 depicts a modular apparatus similar to that shown in Fig. 5. This variation is intended to be more economical than the process depicted in Fig. 5 because less window material is thrown away. In this variation, segments of window material 30 are severed from a continuous web (not shown) and transferred to the surface of vacuum cylinder 16 where they are inserted at proper spacing under paper web 12 and are carried to diecutting cylinder 14, which cuts through both paper and window material. While vacuum cylinder 16 holds the film window, chip removal chute 21 removes the paper chip 20. As the web progresses, it is picked up by large vacuum cylinder 24. As each window and cutout pass frame removal chute 32, the frame portion 31 of each window segment is picked up and diverted away for disposal. Each cutout with its nested film window then proceeds to intermittent extrusion head 36 which is synchronized with web speed such that it lays a layer of film-forming material over each film window. The extrusion head has the proper width and on-off cycle so that the extruded material just contacts the edges of each cutout. The extruded material serves as the bonding agent for the film window nested in each cutout and also forms a two-layer window. The extruded material is preferably a radiation curable acrylic prepolymer as described below but may be any suitable film-forming material. For example it may be a thermoplastic polymer such as polyethylene if the envelope or mailer is not intended for exposure to high temperatures. The large vacuum cylinder 24 and curing module 26 shown in Fig.6 are required for curing, setting, or drying certain film-forming extruded materials. If a thermoplastic film such as polyethylene is used, large energy input is not needed and module 26 could be eliminated. Of course, it should be apparent that a rotary screen, flexographic or gravure printing technique could be used instead of the intermittent extrusion technique shown in Fig. 6. Fig. 8 shows a diagrammatic side sectional view of another suitable apparatus for manufacturing the mailing units of this invention. A web of paper or paper-like material advances from a supply roll (not shown) from the right and passes between diecut cylinder 14 and anvil cylinder 16, causing cutouts to be made at regular intervals along the web. Anvil cylinder 16 is also a vacuum cylinder by which chips 20 are carried around to chip removal chute 21 where they are picked up for disposal, leaving cutout openings 49. The web is then picked up by continuous belt 44 so that each cutout opening 49 is lying against the belt as it passes under print cylinder 19. As these cutout openings pass under rotary screen cylinder 19, polymerizable material 11 , (a prepolymer formulation) is applied as a liquid film into each cutout 49. The continuous belt 44 has a surface comprised of non-stick material such as polytetrafluoroethylene (Teflon), or a silicone polymer. The continuous belt 44, carried by rotating cylinders 45 and 46, carries the web through curing enclosure 26 wherein energy sources 27, such as ultraviolet lamps, cause the liquid films 48 to polymerize, forming solid "cast" films. Preferably, the cast films are about 1.0 to 1.4 mils thick, but may range from 0.6 to 3.0 mils. Web speed, length of the curing enclosure, and polymerization rate are synchronized such that each film is completely cured when it exits the enclosure. The low energy surface of the continuous belt allows the cured polymer film segments to peel away from the belt surface. Fig 8 shows the prepolymer material being applied by the rotary screen method. Other methods of applying liquid films in pattern formation may be used if the applied films are thick enough, e.g. gravure, flexography, or intermittent extrusion. Cylinders 50 and 51 comprise a patterned calendering station where high pressure can be applied, if needed, at the line where the edges of each window meet the edges of its cutout. If the cast film material is not precisely positioned, any overlap may cause an increase in total thickness beyond the thickness of the paper web, which would not be in accord with the objective of this invention. The calendering operation compresses any high points so that all areas are coplanar. It is preferred that compression force should be applied only around the perimeter of each cutout. Fig. 9 is a cross sectional view of the cast film window as produced by the process of Fig. 8. It is preferable that the edges of the cast film penetrate slightly into the pores of the paper, enhancing the strength of the bond. Fig. 10 is diagrammatic side sectional view of yet another apparatus suitable for manufacturing the envelopes and mailer intermediates of this invention. Paper and film webs advance together from the upper right and wrap idler 40 and then pass between diecut cylinder 14 and anvil/vacuum cylinder 33 where a window cutout is made simultaneously through both plies. Paper chip 20 is then removed by a chip removal chute (not shown). As the web moves onto belt 44, each cutout with its nested window comes into contact with bonding agent 23 which has been deposited on belt 44 by print cylinder 38 in the precise locations required to register with the abutting edges of each window and its cutout. The web then proceeds through curing module 26, causing the bonding agent to be set, cured, dried, or otherwise converted to a solid. As in Fig. 8, the surface of the belt is comprised of a low surface energy material so that the bonding agent may readily peel away. In Fig. 10 belt 44 is a vacuum belt and support runner 35 comprises a vacuum chamber. In Fig. 10 the pattern of bonding agent 23 applied to belt 44 is configured to coincide with the abutting edges only. Fig. 11 shows print cylinder 38 having raised print areas which match the entire window area. In this variation, bonding agent is cast over the entire window and onto the edges of the cutout in the paper. Thus each window has two layers, as shown in Fig. 13. In all the embodiments and all the processes described, the envelope or mailer front ply is preferably paper, but may be any convenient sheet material generally used for envelopes and mailers. In those instances wherein the window is cut from a web or segments of a web, the window is preferably a transparent film material such as polyester or cellophane, but may be any convenient sheet material, such as glassine, having sufficient transparency to allow reading address information written on a ply inside the envelope or mailer or written in reverse on the under surface of the window itself. The bonding agent may be an adhesive, such as a polymer latex, a resin-based hot melt, a heat-cure prepolymer or a radiation-cure composition comprising a mixture of acrylic monomers and oligomers. Such a liquid mixture of acrylic monomers and oligomers is converted to a solid by the energy of ultraviolet or electron beam radiation. It is preferred that heat resistant bonding agents be used in mailers which are to be imaged in laser printers because of the high temperatures to which they are exposed in the fusing stations of these printers. Radiation curable acrylic formulations are preferred for their excellent heat resistance. Non-heat resistant bonding agents are adequate for envelopes which are not generally subjected to high temperatures. It is possible that in some cases the bonding agent could be the abutting edge of the window itself or the abutting edge of the cutout in the mailer or envelope ply. For example, where heat resistance is not a consideration, the window may be a thermoplastic material and bonding may be effected by the application of heat or ultrasonic energy. Another possibility is to apply a liquid such as water at the juncture of the abutting edges and then apply a fusible powder, which adheres to the liquid by surface tension, (as in the printing technique called thermography), and then fuse the powder with heat. The polymerizable liquid may be any conventional formulation suitable for casting polymeric films. One suitable formulation comprises a mixture of acrylic monomers and oligomers and may include viscosity modifiers and free radical initiators. Such formulations are converted to solid polymers by crosslinking initiated by ultraviolet or electron beam radiation. Such formulations are disclosed in U.S. 5,418,205, which is incorporated herein by reference. The following formulations of liquid prepolymers curable by ultraviolet or electron beam radiation are typical of those which are suitable bonding agents for edge bonding of transparent windows cut from rolls of window material, or as castable film windows which extend over the entire cutout area. Percent by Weight 1. Trimethylolpropane triacrylate (5) 17 - 23 1 ,6-hexanedioldiacrylate (1) 55 - 70 styrene-maleic anhydride (4) 5 - 8 free radical initiator (3) 8 - 11 trimethylolpropane triacrylate (5) 28 - 35 1 ,6-hexanedioldiacrylate (1) 25 - 30 styrene-maleic anhydride (4) 5 - 8 monohydroxy pentacrylate (6) 3 - 5 urethane acrylate (2) 8 - 12 hexyl carbitol 8 - 12 free radical initiator (3) 9 - 13 1. SR-238 from Sartomer 2. CN-962 from Sartomer 3. Iracure 500 from Ciba Geigy 4. SMA 1000A from Arco Chemical 5. SR-351 from S artomer 6. SR 9041 from Sartomer In manufacturing methods wherein windows are cut from web material, any process may be used which insures that the coextensive edges of the window and the cutout abut sufficiently for effective bonding. When the window is cut from a web or a segment of a web, it is preferred that the window and the cutout be cut simultaneously with the same cutting tool, assuring a perfect fit. This requires that the envelope ply and the window material ply lie one on the other when the cut is made. However, it may be possible to cut each in a separate operation and then transfer the window into the opening of the cutout. Once the window is positioned in the cutout, it is necessary to maintain the window in position while the bonding agent is applied and cured, dried or set. Figs. 7a through 7d show a sequence of fragmentary cross sectional views of the paper web and window material according to the processes shown in Figs. 5, 6 and 10, as the web advances from diecut cylinder 15 to just beyond the point of application of bonding agent. In 7a, cut 25 has been made through paper and window material; in 7b the paper chip has been removed; in 7c the frame material has been removed and the window has been pulled down against the vacuum surface, and in 7d bonding agent has been applied to the abutting edges. When bonding agent is applied and cured, dried, or set, its thickness may be such that its surface is higher than the surface of the mailer substrate ply at the line of abutment of the edges. This can occur with any of the processes depicted and described herein. If this excessive thickness occurs, it is necessary to perform a calendering operation in these areas of excess thickness. Fig. 16 shows such an area where bonding agent 23 protrudes above the substrate surface. Fig. 17 shows the result of calendering (compression) so that the final result is a totally coplanar product. Application of pressure may cause the bonding agent 23, the paper substrate 12, or the window material 22, or all three, to be compressed. In the processes as shown in Figs. 5, 6 and 10, paper and window material are cut simultaneously by the same blade. This is preferred because a perfect fit of the window in the cutout is assured. However, other manufacturing processes may well be devised which use other means for assuring a practical degree of fit. It is not intended to restrict the present invention to any particular manufacturing process or method. Conventional mailers and envelopes, as shown in Figs. 1 and 4, have cutouts which have smooth, straight sides. This invention includes cutouts with such smooth, straight sides, but also includes serrated cuts. Fig. 14 is a fragmentary plan view of an envelope or mailer ply having a cutout with smooth, straight sides and a window with similar smooth, straight sides lying within the cutout. Fig. 15 is a fragmentary plan view of an envelope or mailer having a cutout with serrated sides and a window with matching serrations lying within the cutout. Serrated cuts provide for stronger bonds at the abutting edges between the window and the paper ply due to an increase in the extent of contact where the edges abut. This is analogous to dovetailing in the construction of furniture. In its broadest embodiment, the invention comprises a mailing unit (envelope, mailer, or mailer intermediate) having a cutout opening in its front ply, a transparent or translucent window having a size and shape corresponding to the cutout opening and positioned in the cutout opening such that the edges of the window abut and are bonded to the edges of the cutout opening, adhering the window in the plane of the front ply of the mailing unit. A suitable process for manufacturing the mailing units of this invention may comprise the following steps: 1. Advancing a web of paper or paper-like sheet material from a supply roll and a web of transparent (or translucent) sheet material from another supply roll such that the paper web and the transparent web lie in parallel and contiguous contact with each other. 2. Advancing the two webs together through a diecut station where window cutouts are made through both plies at regularly spaced intervals along the length of the contiguous webs so that a chip of paper and a window of transparent material are simultaneously severed from the webs at each regular interval. 3. Removing and discarding the paper chips from the advancing contiguous webs while retaining the windows of transparent material in register within the cutouts such that the edges of the windows of transparent material abut the edges of the cutouts in the plane of the paper. 4. Removing the excess transparent material from which the windows have been cut. 5. Advancing the web through an application station where bonding agent is applied where the edges of windows of transparent material abut the edges of cutouts in the paper web. 6. Advancing the web through a station where appropriate energy is directed to the bonding agent to cause the bonding agent to be converted to a non-tacky solid, adhering the edges of the transparent windows to the edges of the cutouts such that the transparent windows lie in the plane of the paper web. Another suitable process for manufacturing the mailing units of this invention comprises the following steps: 1. Advancing a web of paper or paper-like sheet material from a supply roll through an application station where segments of a transparent or translucent sheet material are positioned at regular intervals along the web. 2. Advancing the web through a diecut station where window cutouts are made simultaneously through both paper web and transparent material at each of the regular intervals, forming chips of paper and windows of transparent material. 3. Removing and discarding the chips of paper while retaining the windows of transparent material within the cutouts in the plane of the paper such that the edges of the windows of transparent material abut the edges of the cutouts in the paper. 4. Removing and discarding the excess transparent material from which the windows have been cut. 5. Advancing the web through an application station where bonding agent is applied where edges of windows of transparent material abut the edges of cutouts in the paper. 6. Advancing the web through a station where appropriate energy is directed to the bonding agent to cause the bonding agent to be converted to a non-tacky solid, thus adhering the edges of the transparent windows to the edges of the cutouts such that the transparent windows lie in the plane of the paper. Still another suitable process for manufacturing the mailing units of this invention comprises the following steps: 1. Advancing a web of paper or paper-like material from a supply roll through a die cut station where window cutouts are made at regular intervals along the web. 2. Removing and discarding the chips of paper created by the cutouts. 3. Advancing the web through an application station where films of polymer-forming liquid are applied into each cutout opening such that the liquid films make contact with the edges of the cutout openings. 4. Advancing the web through a curing station where the liquid films are converted to solid, transparent polymer. It should be kept in mind that when reference is made to transparent material, the intention is to include both transparent and translucent materials, and when reference is made to paper, the intention is to include both paper and paper-like sheet materials. The processing steps required for manufacturing the mailing units of the invention are well known and widely practiced in the industry. These processes include die cutting of paper and polymer films, removal of severed chips, application of adhesives and other liquids in pattern formation, curing of polymer- forming liquids, drying of aqueous coatings, radiation by ultraviolet and electron beam, and transporting webs and sheets by vacuum cylinders and vacuum belts. The preferred method for high speed manufacturing the mailing units of the invention includes the steps of cutting window openings in a first sheet material which forms the major portions of the mailing units, cutting windows from a second sheet material to form windows, positioning the windows in the cutout openings in the plane of the first sheet material such that their edges abut, maintaining abutting registration of edges of windows and cutout openings while forming a substantially permanent bond between the first and second sheet materials at their abutting edges. Another high speed method for manufacturing the mailing units of the invention includes the steps of cutting window openings in a sheet material which forms the major portions of the mailing units, applying a polymer- forming liquid within the window openings such that the liquid makes contact with the edges of the openings, and curing the polymer-forming liquid to convert it to transparent or translucent solid polymer film windows which lie in the plane of the sheet material and are bonded to the edges of the window openings. What is claimed is:

Claims: 1. A mailing unit having a transparent or translucent coplanar window comprising a first sheet material forming the major portion of said mailing unit, said first sheet material having a window cutout with edges encompassing said cutout, and a second sheet material forming said window, said second sheet material having edges coextensive with and bonded to the edges of said window cutout in said first sheet material. 2. A mailing unit wherein a first sheet material forms the major portion of said mailing unit, said mailing unit having a window- forming cutout therein and a transparent or translucent second sheet material in said cutout wherein said first sheet material is coplanar with said second sheet material, and the edges of said cutout and said window material are coextensive and are bonded to one another. 3. The mailing unit of claim 1 wherein said second sheet material is resistant to degradation by hot fuser rolls in laser printers. 4. The mailing unit of claim 1 wherein said edges of said cutout and of said window are serrated. 5. The mailing unit of claim 2 wherein said edges of said cutout and said window material are serrated. The mailing unit of claim 1 wherein said second sheet material comprises a polymer film derived from a liquid prepolymer. 6. The mailing unit of claim 1 wherein said bonded edges are compressed. The mailing unit of claim 2 wherein said bonded edges are compressed. The mailing unit of claim 1 wherein said second sheet material comprises a first layer and a second layer, said first layer comprising a pre-formed transparent or translucent sheet material and said second layer comprising a polymer film derived from a liquid prepolymer. 7. A process for the manufacture of mailing units having coplanar transparent or translucent windows comprising the steps of: a. Acquiring a first sheet material for forming the major portion of said mailing units; b. Acquiring a second sheet material for forming said transparent or translucent windows; c. cutting window openings in said first sheet material and windows from said second sheet material such that the size and shape of said openings and said windows coincide; d. placing said windows into said cutouts such that the edges of said windows abut the edges of said cutouts and both sheet materials lie in the same plane; e. applying a bonding agent to said abutting edges such that a substantially permanent bond is formed between said abutting edges of said first and second sheet materials. 8. The process of claim 10 wherein said first and second sheet materials are derived from continuous webs supplied from rolls. 9. The process of claim 10 wherein said cutouts from said first sheet material and said windows from said second sheet material are formed simultaneously with the same cutting mechanism. 10. A process for the high speed manufacture of mailing units having transparent or translucent windows comprising the steps of: a. advancing a web of paper or paper-like sheet material from a supply roll through a diecut station where window cutouts are made at regular intervals along said web, severing chips from said cutouts; b. removing and discarding said chips; c. advancing said web through an application station where films of liquid are applied into each of said cutouts to form films spanning said cutouts such that said liquid films make contact with the edges of said cutouts; d. advancing said web through a curing station where said liquid films are converted to solid. 11. A process for high speed manufacture of mailing units having coplanar transparent or translucent windows comprising the steps of: cutting openings in a first sheet material which forms the major portion of said mailing units, cutting windows from a second sheet material to form windows, positioning said windows in said cutout openings in the plane of said first sheet such that the edges abut, and forming a substantially permanent bond between said first and second sheet materials at their common abutting edges. 12. The process of claim 14 wherein said edges are serrated. 13. The process of claim 14 including the additional step of calendering said abutting edges.

Inventors: SKEES HUGH, SKEES, HUGH
Applicants: SKEES HUGH, SKEES, HUGH
Application year: 2000
Main classification: B65D27
IPC codes: B31B19, B65D27