belt assembly comprises a teflon impregnated, fiberglass belt received around third and fourth rollers. The belt assemblies are supported in a frame structure such that the first and third rollers form an input nip, and the second and fourth rollers form an output nip, with the endless belts in facing relation. The first and second rollers are fixed in position, with the third and fourth rollers being slidably suspended relative to the first and second rollers. The third and fourth rollers are biased downwardly from their suspended position toward the first and second rollers to form spaced, but pressurized input and output nips. The first, or lower, input roller is heated by an internal cartridge heater to a temperature of about 200"C. The heated input nip thus defines an initial laminating stage. A heating platen, positioned in abutting relation with an upper portion of the metallic belt adjacent to the first roller is heated to a temperature of about 160°C to define a full laminating stage. Fan cooled heat sinks are positioned in abutting relation adjacent to the output nip for cooling the metallic and fiberglass belts passing therebetween. In particular, the instant apparatus is useful for laminating a security card system comprising an amorphous copolyester backing sheet, a polyvinyl chloride (PVC) cover sheet, and a security image positioned between the

sheets. The security image is preferably reverse printed via conventional thermal dye transfer technology onto the underside of the cover sheet so that the security image is securely located between the sheets where it cannot be tampered with. When viewed through the upper surface of the cover sheet, the reverse printed image appears in its correct orientation. The amorphous copolyester and PVC sheets are compatible polymers which effectively fuse together under heat and pressure without the use of an intermediate adhesive. In use, the rotating belts are operative for transporting the overlapping cover and backing sheets between the input nip and the output nip. The overlying sheets are inserted into the input nip of the apparatus with the cover sheet facing downwardly, wherein the cover sheet is initially laminated to the upper backing sheet under the heat and pressure of the input nip rollers. After the initial lamination, passage over the adjacent heated platen further heats the pre- laminated sheets while in a fixed position, wherein the sheets are able to fully fuse or laminate together. The fused, laminated sheets are thereafter cooled by passage between the fan-cooled heat sinks. Accordingly, among the objects of the instant invention are the provision of a two-stage laminating device wherein two thermoplastic sheets are pre-laminated under heat and pressure, fully laminated under heat

alone, and then cooled; the provision of a laminating device including facing endless belts for transporting sheet materials through a pre-lamination station, a full laminating station, and a cooling station; and the provision of a laminating device including a heated input nip, a heated platen and fan cooled heat sinks. Other objects, features and advantages of the invention shall become apparat as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.

Description of the Drawings: In the drawings which illustrate the best mode presently contemplated for carrying out the present invention: Fig. 1 is a front view of the laminator apparatus of the instant invention; Fig. 2 is a rear view thereof; Fig. 3 is a top view thereof; and Fig. 4 is a cross-sectional view thereof taken along line 4-4 of Fig. 3.

Description of the Preferred Embodiment: Referring now to the drawings, the laminator apparatus of the instant invention is illustrated and generally indicated at 10 in Figs. 1-4. As will

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hereinafter be more fully described, the instant laminator apparatus 10 is operative for laminating face- to-face thermoplastic sheet materials, such as those types of sheet materials used in constructing security cards. More specifically, the instant invention 10 has been found to be particularly useful in fusing a security card system developed by Minnesota Mining and Manufacturing Company of Saint Paul Minnesota, and described in U.S. Patent Application No. 08/128,484 which is incorporated herein by reference. The subject security card system generally indicated at 12 in Fig. 4, comprises a backing sheet 14, a cover sheet 16, and a security image (not shown) , with the security image preferably being reverse printed on the inner surface 18 of the cover sheet 16 so that it is located between the laminated sheets 14, 16 when secured together. When viewed through the upper side of the cover sheet, the reverse printed security image appears in its correct orientation. The backing and cover sheets 14, 16 are laminated in direct contact together without an intermediate layer of adhesive, wherein the backing sheet 14 preferably comprises an amorphous copolyester film, and the cover sheet 16 comprises a rigid polyvinyl chloride film. The amorphous copolyester backing sheet 14 is preferably pigmented with titanium dioxide so that it is opaque white, while the PVC cover sheet 16 is

preferably transparent, although other color schemes and arrangements are also suitable. In most instances, the backing sheet 14 is considerably thicker than the cover sheet as it is intended to provide most of the rigidity and strength of the assembled card 12. For example, the backing sheet 14 preferably has a thickness of between about 20 and 22 mils, and the cover sheet 16 preferably has a thickness of between about 7 and 10 mils for a total card thickness of between about 27 and 32 mils. The particular advantage of the subject security card system 12 is that good adhesion can be achieved between PVC and amorphous copolyesters at relatively low temperatures, e.g., at temperatures of about 150"C. The adhesion can be effectively achieved because both amorphous copolyesters and PVC are softened during the lamination process, and both contract on cooling at about the same rate, thereby reducing warping problems encountered with other existing card materials. The instant laminator apparatus 10 comprises upper and lower belt assemblies generally indicated at 20 and 22, which are supported in closely spaced adjacent relation by a frame assembly comprising a bottom wall 24, and parallel front and rear walls, 26 and 28 respectively. The lower belt assembly 22 comprises a stainless steel belt generally indicated at 30 received around

first and second metallic rollers 32, 34 respectively, and the upper belt assembly 20 comprises a teflon impregnated, fiberglass belt generally indicated at 36 received around third and fourth metallic rollers, 38 and 40 respectively. Both the stainless steel belt 30 and the fiberglass belt 36 preferably have thicknesses of about .003 inches. The steel belt 30 is commercially available from Belt Technologies of Agawa , MA, and the fiberglass belt 36 is available from Greenbelt Industries, Inc. of Buffalo, NY. The rollers 32, 34, 38, 40 preferably comprise aluminum rollers having shafts 32S, 34S, 38S, 40S. It is pointed out that shafts 32S and 38S are hollow, while shafts 34S and 40S are solid. The belt assemblies 20, 22 are supported in the frame such that the first and third rollers 32, 38 from an input nip, and the second and fourth rollers 34, 40 form an output nip, with the endless belts 30, 36 in facing relation. The first and second rollers 32, 34 are fixed in position, with the third and fourth rollers 38, 40 being slidably movable relative to the first and second rollers 32, 34. More specifically, the shaft of each roller is received through a pair of spaced bearing mounts generally indicated at 42A, 42B, 42C, and 42D. Each bearing mount 42 comprises a bearing 44A, 44B, 44C, 44D which is supported in a bearing holder 46. Bearings 44A and 44C each comprise a roller-type bearing, while

bearings 44B and 44D comprise sleeve-type bearings. Furthermore, the sleeve bearings 44B and 44D are mounted in a hardened outer sleeve 45. Each bearing holder 46 includes a recess 48 for receiving the bearing 44 therein, and further includes grooves 50 in the side edges thereof. The grooves 50 of the bearing mounts 42 are slidably received in respective slots 52 in the front and rear walls 26, 28 of the frame assembly so that the bearing holder 46 engages both the inner and outer surfaces of the walls 26, 28. The bearing mounts 42A and 42B rest against the bottom of their respective slots 52, and thus maintain the first and second rollers 32, 34 in a fixed vertical position. It is pointed out that the recesses 48B in the bearing mounts 42B (second roller 34) are elongated in a horizontal direction to allow sliding horizontal movement of the axis of the second roller 34 with respect to the first roller 32. In this connection, a set 54 is extended through a threaded opening in the side wall of the bearing mount 46B and engaged with the hardened outer sleeve 45 to adjust the distance between the axis of the first roller 32 and the axis of the second roller 34. This set screw arrangement is operative for adjusting the parallelism of the first and second roller axes as well as for taking up or tightening slack in the steel belt 30. The bearing mounts 42D for the fourth roller 40 have the same elongated recess 48D

and set screw 54 for adjustment of the fourth roller axis with respect to the third roller axis. The bearing mounts 42C, 42D for the third and fourth rollers 38, 40 are suspended in the frame assembly by screws 56 which extend downwardly through spaced suspension bars 58 attached to the front and rear walls 26, 28. The head 60 of the screw 56 rests on top of the bar while the shaft 62 passes through an opening (not shown) in the bar 58 and extends into a threaded bore (no shown) in the top of the respective bearing holder 46. A compression spring 64 is received around each screw 56 and captured between the top of the respective bearing holder 46 and the bottom of the respective suspension bar 58 to bias the third and fourth rollers 38, 40 downwardly from their suspended position toward the first and second rollers 32, 34. Rotation of the screw 56 permits adjustment of the vertical spacing between the third and first rollers 38, 32 (input nip rollers) and the fourth and second rollers 40, 34 (output nip rollers). In this regard, the belt assemblies 20, 22 are adjusted so that there is at 25 mil spacing between the input rollers 32, 38 and between the output rollers 34, 40, the spacing being slightly smaller than the combined thickness of the security card sheets (27-33 mils) . Since the third and fourth rollers 38, 40 are biased downwardly toward the

first and second roller 32, 34, the roller pairs form spaced, but pressurized input and output nips. The first, or lower, input roller 32 is heated by a conventional cartridge heater 66 to a temperature of between about 190°C and about 215'C, but more preferably to a temperature of about 200"C. The cartridge heater 66 is slidably received in the center of the hollow roller shaft 32S and is energized by a conventional electric source (not shown). The input nip (rollers 32, 38) thus defines an initial or pre-laminating stage for fusing the cover and backing sheets 14, 16 together under pressure and heat. Referring now to Fig. 4, a full laminating stage is defined by a 1/2 inch thick aluminum heating platen 68, positioned in abutting relation with an upper portion of the steel belt 30 adjacent to the first roller 32. The platen 68 is preferably heated to a temperature between about 150'C and about 170"C, and more preferably to a temperature of about 160"C. Heating of the platen 68 is accomplished by means of a rubber plate heater 70 glued to the bottom surface of the platen 68. A rubber plate heater 70 of the type contemplated is available from Hotset, Inc. of Battle Creek, MI. Alternatively, other heating devices, such as cartridge-type heaters, could be used to heat the platen 68.

In order to cool the belts 30, 36 and the laminated sheets 14, 16 held therebetween, first and second fan cooled heat sinks generally indicated at 72, 74 respectfully, are positioned in abutting relation adjacent to the output nip (rollers 34, 40). More specifically, a first aluminum heat sink 72 is positioned between the front and rear walls 26, 28 of the frame, with the body portion 72B in abutting relation with the upper portion of the steel belt 30. Fasteners 76 extend through the front and rear walls 26, 28 of the frame and into openings (not shown) in the heat sink 72 to fixedly secure the heat sink 72 in position. A second heat sink 74 is positioned between the front and rear walls 26, 28 of the frame assembly with the body portion thereof 74B in abutting relation with the lower portion of the fiberglass belt 36. A second set of fasteners 78 extend through vertical slots 80 in the frame walls 26, 28 and into the second heat sink 74. Springs 82 are secured between the fastener pairs to draw the second movable heat sink 74 downwardly into compressing relationship with the first fixed heat sink 72. The fins 72F, 74F of the heat sinks 72, 74 extend perpendicular to the direction of travel of the belts 30, 36 wherein first and second fans 82, 84 mounted to the rear wall of the frame respectively blow air over the fin surfaces 72F, 74F in a direction perpendicular to the direction of belt

travel. To facilitate rapid air movement and optimize cooling, the air is moved through openings 86, 88 in the front and rear walls 26, 28 of the frame assembly. In use, the belts 30, 36 are rotated simultaneously in opposite directions for transporting the overlapping cover and backing sheets 14, 16 between the endless belts from the input nip to the output nip. Rotation of the belts 30, 36 is accomplished via an electric motor generally indicated at 90 and gear system. The body 92 of the electric motor 90 is mounted to a bracket 94 attached to the rear wall 28 of the frame assembly. The drive shaft 96 of the motor 90 includes a worm gear portion 98 for rotating a drive gear 100 mounted on the rear end of the shaft 34S of the second roller 34 (Fig. 2, 3). Rotation of the lower belt assembly 22 is transferred to the upper belt assembly 20 by a pair of intermeshing transfer gears 102, 104 mounted on the front ends of the shaft 34S, 4OS of the second and fourth rollers 34, 40 (Fig. 1). The motor 90 and gear assembly are preferably timed for transporting cards through the apparatus at a rate of about 0.25 inches per second. The instant device is thus operative for transporting a conventional size ID card through the laminator at a rate of about 1 card per minute. The apparatus 10 further includes upper and lower steering assemblies generally indicated at 106 and 108

for maintaining proper alignment and rotation of the belts 30, 36 on their respective rollers. Each steering assembly 106, 108 comprises a shaft 110 mounted between the front and rear walls 26, 28 of the frame. The shaft 110U of the upper steering assembly 108 extends immediately beneath the upper portion of the fiberglass belt 36 adjacent the input nip, and the shaft 110L of the lower steering assembly extends immediately above the lower portion of the steel belt 30 adjacent to the input nip (Fig. 4) . Mounted on each of the shafts 110 is a mating pair of truncated cone rollers 112 with the larger diameter ends of the roller 112 facing toward the outer ends of the shafts 110. In this regard, as the belts 30, 36 rotate, if either belt should skew toward one side or the other, the belt will ride upwardly on the corresponding truncated roller 112, wherein it will be urged back downwardly into its normal rotating position. The apparatus 10 is intended to be used with the cover sheet 16 of the card system facing downwardly and the backing sheet facing 14 upwardly. As the overlying sheets 14, 16 are fed into the input nip, the backing and cover sheets 14, 16 are pressed together under the pressure of the nip while the cover and backing sheets 14, 16 are heated by the heated lower roller 32 of the input nip. The pressure of the input nip squeezes out air bubbles from between the sheets 14, 16 prior to

laminating, and further maintains the cover and backing sheets 14, 16 in proper registration during initial heating by the roller 32. Maintaining the sheets 14, 16 in proper registration during the initial heating is extremely important, since the plastic materials become somewhat soft, and movement of the sheets at their interface while in a molten state will cause smudging or smearing of the security image printed on the inner side 18 of the cover sheet 16. After the initial lamination, the pre-laminated sheets 14, 16 are transported over the heated platen 68 which further heats the sheets for a longer duration while in a fixed position wherein they are able to fully fuse or laminate together. It is noted that the longer exposure to heat over the platen 68 significantly softens the upper backing sheet 14 to a point wherein the surface grain or texture of the fiberglass belt 36 can be unwantedly imprinted on the back surface 114 of the backing sheet 14. In this connection, a lower portion of the fiberglass belt 36 directly above the heating platen 68 is cooled by a fan 116. The air directed across the fiberglass belt 36 keeps the back surface 114 of the backing card 14 sufficiently cool and rigid so as not to be imprinted with the surface texture of the fiberglass belt 36. The laminated sheets 14, 16 are thereafter cooled to almost room temperature by passage between the fan-cooled

heat sinks 72, 74. The sinks 72, 74 effectively remove almost all of the heat from the sheets 14, 16 prior to exiting from the apparatus between the output nip. It can therefore be seen that the instant invention provides an effective laminating apparatus 10 which is effective for pre-laminating a pair of sheet materials under pressure and heat, further heating the pre- laminated sheets to achieve a full bond, and then cooling the laminated sheets prior to exiting the apparatus. The apparatus achieves these objectives by providing a pressurized input nip having a heated roller 32. Sheet materials passed through the input nip are laminated under the pressure and heat of the nip. The pre- laminated materials are then passed over a heated platen 68 for further heating of the sheets materials to achieve a full bonding of the materials. The fully laminated sheets are then cooled by fan cooled heat sinks 72, 74 prior to passage out of the apparatus through a pressurized output nip. For these reasons, the instant invention is believed to represent a significant advancement in the art which has substantial commercial merit. While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made

without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.