Background of the Invention U. S. Pat. No. 6,347, 585 discloses a gap adjusting device for a rotary press comprising two rollers separated by an adjustable eccentric member.

U. S. Pat. No. 5,456, 871 discloses a system for adjusting a calendaring gap which employs load measuring units and active feedback, typically mediated by a microprocessor.

U. S. Pat. App. Pub. No. US2002/0014509 Al discloses a nipping roller gap adjusting device having a minimum gap setting means which includes an opposing pair of stops, one attached to a moving assembly that bears a roller and the other attached to the apparatus frame.

Summary of the Invention Briefly, the present invention provides an apparatus comprising first and second rollers defining a gap therebetween and at least one gapping block positioned between the first and second rollers such that the gapping block determines and maintains a minimum gap width. The gapping block comprises a rigid gapping block body and four or more load wheels rotatably attached to the gapping block body and is positioned

between the first and second rollers such that at least two load wheels contact each roller. In a further embodiment, the width of the gapping block may be adjustable.

In another aspect, the present invention provides a method of laminating two or more sheet materials together by passing the sheets concurrently into a gap between a first roller and a second roller of a laminating apparatus, which apparatus additionally comprises at least one gapping block positioned between the first and second rollers such that the gapping block determines and maintains a minimum gap width.

In another aspect, the present invention provides a method of laminating two or more sheet materials together by passing the sheets concurrently into a gap between a first roller and a second roller of a laminating apparatus, which apparatus additionally comprises at least one gapping block positioned between the first and second rollers such that the gapping block determines and maintains a constant gap width which remains constant throughout the lamination.

In another aspect, the present invention provides an adjustable gapping block comprising: a first gapping block body element having two or more load wheels rotatably attached; a second gapping block body element having two or more load wheels rotatably attached, where the second gapping block body element is assembled with said first gapping block body element so as to allow linear motion of the two elements relative to each other in the direction of gapping block body width, and where at least one surface of either gapping block body element is canted with respect to a facing surface of the other gapping block body element when so assembled; a wedge disposed between the facing surfaces; and an adjusting screw to determine the position of the wedge between the facing surfaces, thereby determining the gapping block body width.

In this application,"to laminate"means to bond together two or more sheet materials.

It is an advantage of the present invention to provide a method of lamination which prevents damage to the continuous web during intermittent lamination of non- continuous sheets to a continuous web.

Brief Description of the Drawing Figs. 1 and 2 illustrate a gapping block according to the present invention.

Figs. 3 and 4 are cross-sections of the gapping block depicted in Figs. 1 and 2.

Fig. 5 is a cross-section of an apparatus according to the present invention taken through the axes of the two rollers of the apparatus.

Detailed Description of Preferred Embodiments With reference to Figs. 1-4, a gapping block according to the present invention comprises a gapping block body which comprises a first gapping block body element 10 and a second gapping block body element 20. Two load wheels 31,32 are rotatably attached to the first gapping block body element 10. Two load wheels 33,34 are rotatably attached to the second gapping block body element 20. Additional load wheels may be mounted to either gapping block body element. Alternately, where no adjustment to gapping block body width will be needed, the gapping block body can be a single body element to which four or more load wheels are mounted. Arrow A indicates the dimension which represents body width of the gapping block. In use with a pair of rollers, the gapping block body width is the linear dimension of the gapping block body measured in the direction parallel to the measurement of the gap width between the first and second rollers. In use, motion of the gapping block body elements in a direction perpendicular to the gapping block body width must be prevented. First gapping block body element 10 may comprise arms 15 which prevent motion of second gapping block body element 20 in one or more direction perpendicular to the gapping block body width. In addition, one or more lateral constraints attached to or forming a part of the apparatus frame (shown in Fig. 5, discussed below) may prevent motion of second gapping block body element 20 relative to first gapping block body element 10 in one or more directions perpendicular to the gapping block body width. First and second gapping block body elements 10,20 may be bolted to one or more lateral constraints after adjustment of the gapping block body width through tapped holes 12, 22.

First gapping block body element 10 and second gapping block body element 20 comprise facing surfaces 11 and 21, respectively. One or both of facing surfaces 11 and

21 is canted. By interaction with surfaces 11 and 21, wedge 40 may be used to adjust gapping block body width. Adjusting screw 41 may be used to alter the position of wedge 40 and thereby the gapping block body width. In one embodiment, adjusting screw 41 has threaded shaft which engages a tapped hole in a lateral constraints attached to or forming a part of the apparatus frame (shown in Fig. 5, discussed below).

Typically, first gapping block body element 10 is bolted to one or more lateral constraints through tapped holes 12, gapping block body width is adjusted by means of adjusting screw 41, and then second gapping block body element 20 is bolted to one or more lateral constraints through tapped holes 22.

With reference to Fig. 5, an apparatus according to the present invention comprises gapping blocks as described above comprising first gapping block body element 10, second gapping block body element 20, load wheels 32,34, wedge 40, and adjusting screw 41. Lateral constraints 50 prevent motion of second gapping block body element 20 relative to first gapping block body element 10 in a direction perpendicular to the gapping block body width. Lateral constraints 50 are attached to the apparatus frame by connections not shown. First gapping block body elements 10 may be bolted to lateral constraints 50 by through holes 51 and tapped holes 12.

Adjusting screws 41 have threaded shafts which engages tapped holes 53 in lateral constraints 50. Gapping block body width is adjusted by means of the action of adjusting screws 41 on wedges 40. Second gapping block body elements 20 may then be bolted to lateral constraints 50 by through holes 52 and tapped holes 22.

The apparatus additionally comprises a first roller 60 comprising a pressing zone 61 having a radius rpl and two gapping block zones 62,63 having a radius rgl.

As shown, the first roller additionally comprises axle portions 64,65 which interact with bearing surface mechanisms 72. Second roller 80 comprising a pressing zone 81 having a radius rp2 and two gapping block zones 82,83 having a radius rg2. Typically, rpl equals rp2 and rgl equals rg2. As shown, the first roller additionally comprises axle portions 84,85 which interact with bearing surface mechanisms 92. A narrow laminating gap is formed between first roller 60 and second roller 80, which are not in contact. The laminating gap of the embodiment shown in Fig. 5 is too narrow to be clearly depicted. Either or both of first roller 60 and second roller 80 may be driven by

known means such as motors and the like. Typically both are driven. Typically first roller 60 and second roller 80 are geared together so that they have the same speed at the gap. In one embodiment, first roller 60 and second roller 80 are driven by a belt drive mechanism interacting with pulleys 68 and 88.

Bearings comprise bearing housings 71,91 and bearing surface mechanisms 72, 92 which are of known types such as ball bearings, roller bearings, needle bearings, and the like. Bearing housings 71,91 are attached to the apparatus frame 100 such that pressure can be brought or maintained on bearing housings 71,91 which tends to bring together first and second rollers 60, 80. The bearing housings may be fixedly attached to frame 100 or attached by means of pneumatic or hydraulic pistons 101 and cylinders 102, as shown. Bearing mechanisms may form a part of drive mechanisms for either or both rollers.

In the laminating method according to the present invention, two or more sheet materials are pressed together by passing them concurrently into a narrow gap between first roller 60 and second roller 80. Typically one or both of first roller 60 and second roller 80 are driven; more typically both. Heat, solvents or adhesives may be applied to one or more layers to aid in bonding. First roller 60 and second roller 80 may be heated by any suitable method but are typically internally heated by a method such as electrical heating or circulation of hot air, water or oil.

The apparatus and method according to the present invention are used to advantage where intermittent lamination is desired, i. e. , where one or more of the layers to be laminated is not continuously present in the laminating gap during lamination. In this case, the product may be a continuous web with non-continuous patches of additional sheet materials laminated thereto. In the case of intermittent lamination, the continuous web could be crushed or damaged if the full laminating pressure were applied when the non-continuous sheet material was not present in the gap. This damage to the continuous web may be prevented by use of the method and apparatus according to the present invention, which maintains a minimum gap width. In addition, if the full laminating pressure were applied when the non-continuous sheet material was not present in the gap, the leading edges of the intermittent laminate may be rounded

during the laminating process, which may be avoided by use of the method and apparatus according to the present invention.

The apparatus according to the present invention has the additional advantage that bearing clearance in the roller bearings is removed from consideration in determining gap width, and therefore variation in bearing clearance is also removed from consideration. Variation in bearing clearance may be especially problematic where laminating rolls are heated. More accurate and consistent gap width may be set using the apparatus according to the present invention. In addition, the apparatus according to the present invention can be used for fixed-gap lamination, where the gap width is essentially constant throughout lamination. To achieve fixed-gap lamination, sufficient force must be applied to the rollers to overcome any resisting force generated by the materials to be laminated.

The apparatus and method according to the present invention are used to advantage in the lamination of catalyst decals to polymer electrolyte membranes, in particular membranes of sulfonate fluoropolymer membranes such as Nation or Flemion. Catalyst decals typically comprises a thin layer of a catalyst dispersion on a backing layer. After lamination of the catalyst dispersion to the polymer electrolyte membrane, the decal backing layer is removed. The apparatus and method according to the present invention are used to advantage with cast membranes of delicate or thin films, typically 100 micrometers in thickness or less, more typically 50 micrometers in thickness or less, and more typically 30 micrometers in thickness or less.

Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and principles of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth hereinabove.