GB2223445A

GB2223445A - Paper laminating apparatus

Info

Publication number: GB2223445A
Application number: GB8818833A
Authority: GB
Inventors: Alan Wilkinson
Original assignee: A W M W DEVELOPMENTS Ltd
Current assignee: A W M W DEVELOPMENTS Ltd
Priority date: 1988-08-09
Filing date: 1988-08-09
Publication date: 1990-04-11
Also published as: GB8818833D0

Abstract

An apparatus for use in the calendaring and subsequent lamination of paper comprises a first roller, a second roller, and a third roller, the arrangement being such that in use: paper is fed between the second and third rollers; the outer surface of the second roller is at such a temperature that anti-set-off powder on the surface of the paper is substantially removed; and the paper is subsequently fed between the first and second rollers for lamination. There is also described apparatus for use in a paper laminating machine capable of removing loose anti-set-off powder from paper prior to lamination, which comprises a first roller, a second roller, and a brush, the arrangement being such that in use the outer surface of the first roller removes loose powder from the surface of paper situated between the rollers and the brush removes powder from the surface of the first roller.

Description

PAPER LAMINATING APPARATUS This invention relates to improvements associated with a paper laminating machine.

Paper laminating machines are used to apply a coating of plastic, paper, or foil, known as a lamina to either a continuous web, or individual sheets, of paper. This is generally achieved by providing the lamina with an adhesive resin and applying the thus provided lamina to the paper by feeding the two through a pair of rollers under pressure. There are generally two methods of lamination, namely dry lamination and wet lamination. In dry lamination the lamina is coated on one side with a resin carried in a solvent,and the solvent is removed prior to the lamination, i.e. the application of the lamina to the paper. In wet lamination the coated lamina is applied to the paper before the solvent is removed. For either type of paper lamination to be successful the paper should have a smooth, even surface, so that air is not trapped between the paper and the lamina.If the surface is not smooth, extra adhesive resin will be necessary, which increases the expense of the process and the resultant product will not be of the same quality as one produced from paper with a smooth surface. When the paper to be laminated has a printed image on its surface it may, especially if it is in the form of individually printed sheets, be coated with a fine powder called anti-set-off spray powder, which is used in the printing industry to stop ink from one sheet of paper being smeared, onto or adhered to (set-off), the sheet above it in a stack of paper on which the ink is not quite dry. Some of this powder becomes trapped in the drying ink and imparts a rough surface to the paper when the ink has dried. The rest of the powder may remain as loose powder on the surface of the paper.

Anti-set-off powder should be removed from paper prior to lamination as it imparts a rough surface to the paper, which allows air to become trapped between the paper and its lamina thereby reducing the quality of the final product.

In the past, anti-set-off powder trapped in the ink has been removed by passing the paper between a pair of rollers under pressure, one of which rollers is heated. The moisture contained in the paper is thereby heated, vaporises, and dissolves the anti-set-off powder. Further, the passage of the paper between the pair of rollers under pressure leads to the crushing of particles of anti-set-off powder. This process is known as calendaring, and has varying success depending on how much powder is on the surface of the paper, and how high a temperature the ink will stand before softening and sticking to the roller surface.

Two methods have been used in the past to remove loose powder from the surface of paper sheets which are to be laminated. In the first process, namely suction cleaning, the sheet passes through a suction system in which loose powder is sucked off the paper surface.

For this process it is necessary to hold the sheet in place as it passes through the suction system, e.g. by suction from below. Although, this process is very efficient, the suction system above and below the paper increases the engineering cost of the machine, and it is generally felt that the improvement in the final laminated product is not sufficient to justify such cost. In the second process, namely brush cleaning, a rotating brush sweeps powder off the paper surface, which powder is then removed from the brush by suction.

Again, the paper sheets have to be held down by suction from below, which is expensive. Another disadvantage of this process is that the rotating brush may damage soft inks printed on the paper.

One aspect of the present invention is an improvement in the removal of loose anti-set-off powder.

According to one aspect of the present invention, there is provided apparatus, for use in a paper laminating machine, capable of removing loose anti-setoff powder from paper prior to lamination, the apparatus comprising; a first roller, provided with an outer surface to which powder may adhere; a second roller which may be driven and which is capable of driving the first roller; and a brush capable of removing powder from the outer surface of the first roller; the arrangement being such that in use: the second roller is driven, causing the first roller to rotate; paper is fed between the rollers by their rotation; the outer surface of the first roller removes, by contact, loose powder from the surface of the paper situated between the rollers; and the brush removes powder from the surface of the first roller as it rotates, such that the outer surface of the first roller is substantially free from powder when after further rotation it contacts paper situated between the rollers.

The outer surface of the first roller is preferably of rubber.

The first roller is preferably supported substantially vertically above the second roller, such that paper passing between the two rollers lies in a substantially horizontal plane.

The second roller is preferably of steel and may be provided with a rubber outer coating. It is preferably mounted such that the top of its outer surface is at the same height as the conveyor system of the paper laminating machine in which it is used. The surface speed of the second roller is preferably driven at the same surface speed as the rest of the conveyor system of the paper laminating machine.

The brush is preferably a cylindrical brush, in which the bristles extend radially outwards, and which is rotably mounted on a support shaft. The brush is preferably mounted substantially vertically above the first roller such that as the brush rotates sequential bristles on the brush are brought into contact with the surface of the first roller. The brush is preferably rotated in the opposite direction to that of the first roller, as this produces an effective brushing action.

The brush is preferably provided with means for removing powder from its surface. Such means preferably comprises a suction area through which the bristles of the brush must pass whilst rotating. The suction area preferably is provided with at least one baffle plate which contacts the bristles, causing them to vibrate, thereby removing powder adhered to the bristles. The bristles of the brush are preferably crimped to increase their stiffness, which aids removal of the powder by the baffle plate. The suction area is also preferably provided with a vacuum system which draws away powder shaken loose from the brush. The vacuum system preferably comprises a filter to trap powder drawn away from the brush. The suction area may be provided with a cowl which extends over the whole of the brush except where the brush contacts the first roller. The cowl assists the vacuum system to obtain satisfactory suction power thereby preventing powder removed from the brush from dropping back on to the first roller. The suction area is preferably situated substantially vertically above the brush. The baffle plate is preferably situated such that it contacts the bristles of the brush just before the bristles rotate into a vertical position. This arrangement allows a maximum amount of powder to enter the vacuum system which is preferably situated substantially vertically above the baffle plates. The first roller, brush and suction area are preferably mounted relative to each other in such a way as to allow their respective orientation to be finely adjusted, such that varying thicknesses of material passing between the rollers can be accommodated without changing their relative orientation.This is particularly important when the paper to be laminated is in the form of individual sheets of paper which are overlapped.

It is also envisaged that a brush may be provided to remove powder from the outer surface of the second roller which may have been picked up by that roller from the side of the paper passing between the rollers which is not contacted by the first roller.

To ensure maximum efficiency in removing loose powder, two apparatuses of the above described type may be arranged in series. The second apparatus should remove any loose powder from the paper which was not removed by the first apparatus. The two apparatuses may have a common driven second roller which would be enlarged to accommodate the two first rollers.

The advantages of this first aspect of the present invention are that most of the loose anti-set-off-spray powder is removed from the surface of the paper to be laminated without the need to use rotating brushes directly in contact with the printed image, which may damage that printed image, and expensive machinery is not needed for suction to be applied to hold the paper dcwn, such that the apparatus according to the first aspect of the present invention is cheap to manufacture and to incorporate into a paper laminating machine.

The apparatus according to this first aspect of the present invention may be incorporated into a wet or dry paper laminating machine or in any process where it is necessary or desirable to remove loose powder and is most particularly adapted for use in such machines which utilize individual sheets, rather than a continous web, of paper. Further, it may be used in a paper laminating machine in which anti-set-off powder trapped in the ink is removed by calendaring. In this latter case the apparatus according to this first aspect of the present invention would treat the paper prior to that calendaring. It is also envisaged that the calendaring apparatus may be driven by the driven second roller of the apparatus according to this first aspect of the present invention.

Conventional calendaring is achieved by passing paper between a heated chrome plated roller mounted over a rubber covered pressure roller. The outer surface of the heated roller is set to the maximum temperature that the printing ink will tolerate without the ink softening and sticking to the roller surface.

The calendaring rollers should be situated as near as possible to the rollers used for the laminating process. Such conventional calendaring rollers are expensive to incorporate into a paper laminating machine, particularly one which utilizes individual sheets ,rather than a continuous web, of paper, as they must be capable of releasing their pre-set pressure if the machine has to be stopped whilst printed paper is running through the machine, to avoid the ink sticking to the heated roller. This involves the use of sophisticated hydraulic and electrical switch gear.

Further costs are also incurred by the critical engineering involved in synchronising the calendaring rollers and the laminating rollers to run at exactly the same surface speed.

A second aspect of the present invention is an improvement in conventional calendaring and laminating rollers.

According to a second aspect of the present invention, there is provided apparatus for use in the calendaring and subsequent lamination of paper, which apparatus comprises: a first roller, which is intended to be driven and which is provided with means for raising the temperature of its outer surface; a second roller, which is mounted so as to contact the first roller and which is capable of applying pressure to the first roller; and a third roller, provided with means for raising the temperature of its outer surface, which third roller is mounted so as to contact the second roller and which is capable of applying pressure to the second roller; the arrangement being such that in use: the first roller is driven, causing the second roller, to rotate, which in turn causes the third roller to rotate; paper is fed between the second and third rollers by their rotation; the outer surface of the second roller is at a temperature such that anti-set-off powder on the surface of the paper is substantially removed; the paper is subsequently fed between the first and second rollers where it may be laminated to a lamina also fed between the first and second rollers.

The first roller is preferably provided with means for raising it surface temperature up to 950C. The first roller is preferably of sturdy construction such that it can withstand pressures of up to about 4 tonnes.

The second roller is preferably of steel and is preferably provided with a rubber outer coating. It is preferably of larger diameter than each of the first and third rollers. The mountings of the second roller are preferably supported by hydraulic jacks which may be used to apply pressure on the first roller via the second roller.

The third roller is preferably provided with means for raising its surface temperature up to 1200C. The third roller is preferably capable of applying pressure to the second roller of up to 700kg. The mountings of the third roller are preferably supported by hydraulic jacks which may be used to apply pressure on the second roller via the third roller. The third roller is preferably mounted so as to allow it to be lifted clear of the second roller, when the machine is stopped whilst paper is situated between the second and third rollers.

The means provided for raising the temperature of the rollers concerned may be, for example, electrical heating elements with thermostatic controls, which is prefered for the third roller, or circulating hot water, which is prefered for the first roller.

The advantage of apparatus according to the second aspect of the present invention is that, as the speed of all three rollers is dictated by that of the first roller, expensive machinery such as that used for the synchronisation of the speeds of conventional calendaring and laminating rollers is not necessary.

Apparatus according to the second aspect of the present invention may be used in wet and dry paper laminating machines, ultraviolet cured laminating systems, ultraviolet cured varnishing systems (both roller and silk screen) and in any finishing process where printed paper causes problems due to excess antiset-off spray powder which has been used during the printing process. It is particularly adapted for use in machines which utilize individual sheets, rather than a continous web, of paper.

As mentioned above, the difference between wet and dry lamination is that in dry lamination the solvent in which the adhesive is dispersed is evaporated prior to the lamination of the lamina to the paper. In the past several methods have been used to remove the solvent.

One such method is to blow air onto the adhesivecoated surface of the lamina to accelerate the rate of evaporation of the solvent. This process greatly increases the time taken for the overall lamination process to be carried out, as although in theory an increase in temperature of the blown air would lead to an increase in the rate of evaporation, in practice, if the temperature of the air is too high, the exposed surface of the adhesive coating forms a skin, which prevents the remaining solvent from evaporating.

Further, although in theory the evaporation rate would be increased by an increase in the speed at which the air is blown, in practice, only low air speeds can be used as when the adhesive coating is still in a liquid form it can be easily blown off the lamina.

An alternative method of evaporating the solvent is to use a heated drum. The lamina is carried over a large diameter metal drum, which is usually chromeplated, with the coated surface of the lamina outermost. The heated surface of the drum causes the evaporation of the solvent nearest to the surface of the drum first, such that a skin does not form on the exposed surface of the adhesive/solvent layer. Again, although in theory one should be able to reduce drying time proportionally to the amount of heat selected, thereby enabling higher running speeds to be achieved, there is, in practice, a maximum limit of about 900C.

At this temperature the most commonly used lamina, OPP (a polypropylene), becomes structurally unstable, e.g.

the lamina starts to shrink. Further, air trapped between the drying drum and the lamina expands upon heating which can cause ridges to form in the lamina.

This effect increases with an increase in the temperature of the outer surface of the drying drum.

These two methods of evaporation may be combined such that a large diameter heated drying drum, running at a surface temperature just below the temperature which would affect the structural stability of the lamina, starts the evaporation of the solvent through the adhesive coating, then warm air is directed at the surface of the adhesive coating to assist in the driving off of the solvent as it rises to the surface.

However, care must still be taken to avoid ridging of the lamina, by the expansion of the trapped air, as it is carried round the drying drum.

The third aspect of the present invention involves an improvement in the removal of a solvent from the lamina in the process of dry paper lamination.

According to a third aspect of the present invention there is provided a drying drum provided with means for raising the temperature of its outer surface and which is provided with an outer coating of a copolymer of tetrafluoroethylene and hexaf luoropropylene.

The advantage of a drying drum according to the third aspect of the present invention is that less air becomes trapped between the drum and the lamina, leading to less distortion of the lamina. This allows, the drying drum to be set to higher temperatures than are possible with a conventional drying drum.

According to a fourth aspect of the present invention, there is provided a method of removing loose anti-set-off powder from paper, which method comprises feeding paper between a first roller which supports the paper and a second roller driven by the first roller, which second roller is provided with an outer surface to which powder may adhere, and which second roller is contacted by a brush which removes powder from the outer surface of the second roller.

According to a fifth aspect of the present invention, there is a provided a method of calendaring and subsequently laminating paper, which comprises feeding paper between a third and a second roller, which second roller supports the paper and causes the third roller to rotate, the outer surface of the second roller being at such a temperature that anti-set-off powder on the surface of the paper is substantially removed, followed by feeding the paper between a first roller and the second roller at the same time as an adhesive coated lamina is fed between the first and second rollers, the outer surface of the first roller being at such a temperature as to facilitate the application of the lamina to the paper, and the first roller being driven causing the second roller to rotate.

According to a sixth aspect of the present invention, there is provided a method of removing a solvent from a lamina coated on one side with an adhesive resin dispersed in a solvent, which method comprises passing the lamina over a drying drum whose outer surface is at a temperature sufficient to evaporate the solvent, and whose outer surface is coated with a copolymer of tetrafluoroethylene and hexafluoro.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which; Figure 1 is a schematic drawing of a dry paper laminating machine which utilizes individual sheets, rather than a continuous web, of paper, incorporating the aspects of the present invention; Figure 2 is a schematic drawing of a detail of the paper laminating machine shown in Figure 1; and Figure 3 is a schematic drawing of a free-standing unit for use in the removal of anti-set-off spray powder from paper, for use on its own or for use in conjunction with other machines, e.g. a paper laminating machine which utilizes individual sheets, rather than a continous web, of paper.

The dry paper laminating machine shown in Fig. 1 comprises apparatus for providing a lamina with an adhesive coating, apparatus for evaporating the solvent from the adhesive coating, apparatus for removing antiset-off powder from sheets of paper to be laminated, and apparatus for laminating the lamina to the sheets of paper.

The lamina (1) is supplied from a reel (2) supported on a support bar (3) and transported along a series of rollers (4) to the apparatus for applying an adhesive coating to the lamina. This apparatus comprises an adhesive reservoir (5) which contains an adhesive resin (6) dispersed in a solvent (7). Mounted above the adhesive reservoir (5) is an adhesive coating roller (8), which is partially submerged in the adhesive resin/solvent mixture, such that rotation of the adhesive coating roller (8) lifts a layer of adhesive resin/solvent mixture from the adhesive reservoir (5). The amount of adhesive resin/solvent mixture lifted out of the adhesive reservoir (5) onto the surface of the adhesive coating roller (8) is controlled by a metering bar (9) mounted above the adhesive reservoir (5) and whose distance from the outer surface of the adhesive coating roller (8) may be adjusted. The metering bar (9) blocks the passage of excess adhesive resin/solvent mixture causing it to fall back into the adhesive reservoir (5) thereby allowing only a predetermined amount of adhesive resin/solvent mixture to be removed from the adhesive reservoir (5) onto the surface of the adhesive coating roller (8). The adhesive coating roller (8) is driven in a direction opposite to that in which the lamina passes through the apparatus for applying the adhesive coating. The lamina (1) is forced into contact with the adhesive coating roller (8) by a pair of lay-on rollers (10a,b) which are mounted above and one slightly to each side of the adhesive coating roller (8). The lay-on rollers (1Oa,b) pre-tension the lamina to allow the adhesive resin/solvent mixture to be evenly coated on the undersurface of the lamina (1).

The lamina (1) then passes from the apparatus for applying the adhesive coating to the apparatus for evaporating the solvent from the adhesive resin/solvent mixture.

This apparatus comprises a drying drum (11) of large diameter, coated with a copolymer of a tetrafluoroethylene and hexafluoropropylene coating (12). The lamina (1) is run over the outer surface of the drying drum (11) with the adhesive resin/solvent mixture coated layer outermost. The outer surface of the drying drum (11) is heated, which causes the evaporation of the solvent from the adhesive resin/solvent mixture coating nearest to the drying drum. Warm air (13) provided from a heated air drying cabinet (14) is directed at the surface of the adhesive resin/solvent mixture and assists in the driving off of the solvent as it rises to the surface. After leaving the drying drum (11) the lamina (1) continues to have warm air (13) directed at it from the heated air drying cabinet (14) until it arrives at the apparatus for lamination.

Meanwhile, sheets of paper (15) to be laminated are fed overlapped into the machine, and arrive first at the apparatus for removing anti-set-off spray powder from the paper prior to being delivered at the apparatus for lamination where the individual sheets are joined to the adhesive-coated lamina. Both the apparatus for removing anti-set-off spray powder and that for lamination are shown in more detail in Fig. 2.

The sheets of paper (15) are fed between a lower steel support roller (16) and an upper rubber coated roller (17). The steel support roller (16) is driven and rotates the rubber coated roller -(17) by contact thereby pulling the paper (1) through between the two rollers. Powder adhering to the surface of the paper (15) is lifted off by the rubber covered roller (17) as it rotates. The powder is then removed from the surface of the rubber covered roller (17) by means of a cylindrical brush (18) mounted above the rubber covered roller (17). The cylindrical brush (18) is provided with bristles (18a) extending radially such that as the cylindrical brush (18) rotates the bristles (18a) are sequentially brought into contact with the surface of the rubber coated roller (17).The brush (18) is rotated in a direction opposite to that of the rubber coated roller (17), in order to remove the maximum amount of powder from the surface of the rubber coated roller (17). Powder is removed from the bristles (18a) of the brush (18) by means of a baffle plate (19) situated above the brush (18), which baffle plate (19) contacts the brush (18) causing powder on the bristles (18a) to be flicked off. The loose powder is then removed from the vicinity of the cylindrical brush (18) by means of a vacuum system incorporated in a hood (20) which extends over the cylindrical brush (18).

The brush (18) is mounted via an adjusting screw (21) which allows the position of the brush (18) with respect to the rubber coated roller (17) to be adjusted. The rubber coated roller (17), brush (18) and hood (21) are mounted by means of a roller assembly support arm (22) which allows the rubber coated roller (17) the brush (18) and the hood (21) to be lifted when the overlapped portions of the paper sheets pass between the steel support roller.(16) and the rubber coated roller (17), without the distance between the rubber coated roller (17) the brush (18) and the hood (21) being affected.

Two anti-set-off powder removal apparatuses are placed in series for removing the loose powder from the surface of the paper. The second apparatus picks up any loose powder not removed by the first apparatus.

The paper is then fed into the apparatus for calendaring and subsequent lamination. This apparatus comprises a chrome-plated laminating roller (23), and a chrome-plated cleaning roller (24) both of which are mounted above and contact a common rubber-covered pressure roller (25) of larger diameter than the laminating roller (23) and the cleaning roller (24).

The sheets of paper are first fed between the chromeplated cleaning roller (24) and the pressure roller (25). The outer surface of the cleaning roller (24) is heated to about 120or which causes moisture contained in the paper (15) to evaporate and dissolve anti-setoff powder trapped in the ink on the surface of the paper (15). Particles of anti-set-off spray powder trapped in the ink, which are not dissolved in this way are crushed by the passage of the paper (18) between the two rollers (24 and 25), to provide the outer surface of the paper (15) with a smooth finish. The sheets of paper (15) then pass over the surface of the pressure roller (25) until they are fed, between the laminating roller (23) and the pressure roller (25) along with the adhesive resin coated lamina (1).The outer surface of the laminating roller (23) is heated up to a temperature of about 950C, which causes the adhesive resin to become more fluid assisting in its adherence to the paper (15).

The laminating roller (23) is driven by the main drive motor of the machine. This roller (23) then causes the rubber-coated pressure roller (25) to rotate when pressure is applied to hydraulic jacks (26) which support the pressure roller (25). The cleaning roller (24) is supported by its own hydraulic jacks (27) and when pressure is applied to those, the cleaning roller (24) is rotated by the pressure roller (25). In this way surface speed synchronisation between all three rollers (24, 24, 25) is achieved.

The cleaning roller (24) is mounted in such a way that, if the machine has to be stopped for any reason whilst a printed sheet is in contact with that roller (24) it is lifted clear of the pressure roller (25) automatically, to prevent the ink softening and causing the sheet to stick to the roller (24).

The resulting laminated paper (29) is finally removed from the machine and separated into individual sheets to form the finished article, e.g. book covers, reference charts, advertising brochures, maps, labels, show cards and point of sale displays.

Figure 3 shows a free-standing unit for use in removing both loose and trapped anti-set-off powder from sheets of paper. In this unit two apparatuses for removing loose anti-set-off spray powder are placed in series. They are similar to that described in the machine shown in Figures 1 and 2 but instead of being driven by two individual support rollers (16) they are driven by a common rubber-covered roller of large diameter (28). Also driven by the same rubber covered roller of large diameter (28) is a cleaning roller (24') identical to that described above for Figures 1 and 2. An additional brush unit (30) is mounted in contact with the rubber covered roller of large diameter (28) for removing any powder picked up by the rubber covered roller of large diameter (28) from the underside of the paper sheet being cleaned.

Such a free standing unit could be fitted into the processing line of a printing, cutting or crushing machine immediately after the paper sheet feeder. It could also be used in any of the many other finishing machines which are adversely affected by spray powder.

Such a free standing unit would preferably be fitted with a variable speed gear box driven from the main drive output of the main machine to synchronise speed ratios and allow the speed of the unit to be adjusted to produce maximum effiency of use for varying sizes of sheet.

Claims

1. Apparatus for use in the calendaring and subsequent lamination of paper, which apparatus comprises: a first roller, which is intended to be driven and which is provided with means for raising the temperature of its outer surface; a second roller, which is mounted so as to contact the first roller and which is capable of applying pressure to the first roller; and a third roller, provided with means for raising the temperature of its outer surface, which third roller is mounted so as to contact the second roller and which is capable of applying pressure to the second roller; the arrangement being such that in use: the first roller is driven, causing the second roller to rotate, which in turn causes the third roller to rotate; paper is fed between the second and third rollers by their rotation; the outer surface of the second roller is at a temperature such that anti-set-off powder on the surface of the paper is substantially removed; and the paper is subsequently fed between the first and second rollers where it may be laminated to a lamina also fed between the first and second rollers.

2. Apparatus according to claim 1, wherein the first roller is provided with means for raising its surface temperature up to 950C.

3. Apparatus according to claim 1 or 2, wherein the first roller is of sturdy construction such that it can withstand pressures of up to about 4 tonnes.

4. Apparatus according to claim 1, 2 or 3, wherein the second roller is of steel and is provided with a rubber outer coating.

5. Apparatus according to any one of the preceding claims, wherein the second roller is of larger diameter than each of the first and third rollers.

6. Apparatus according to any one of the preceding claims, wherein the mountings of the second roller are supported by hydraulic jacks which may be used to apply pressure on the first roller via the second roller.

7. Apparatus according to any one of the preceding claims, wherein the third roller is provided with means for raising its surface temperature up to 1 200C.

8. Apparatus according to any one of the preceding claims, wherein the third roller is capable of applying pressure to the second roller of up to 700kg.

9. Apparatus according to any one of the preceding claims, wherein the mountings of the third roller are supported by hydraulic jacks which may be used to apply pressure on the second roller via the third roller.

10. Apparatus according to any one of the preceding claims, wherein the third roller is mounted so as to allow it to be lifted clear of the second roller, when the machine is stopped whilst paper is situated between the second and third rollers.

11. Apparatus according to any one of the preceding claims, wherein the means provided for raising the temperature of the third roller is an electrical heating element with a thermostatic control.

12. Apparatus according to any one of the preceding claims, wherein the means provided for raising the temperature of the first roller is circulating hot water.

13. Apparatus, for use in a paper laminating machine, capable of removing loose anti-set-off powder from paper prior to lamination, the apparatus comprising: a first roller, provided with an outer surface to which powder may adhere; a second roller which may be driven and which is capable of driving the first roller; and a brush capable of removing powder from the outer surface of the first roller; the arrangement being such that in use: the second roller is driven, causing the first roller to rotate; paper is fed between the rollers by their rotation; the outer surface of the first roller removes, by contact, loose powder from the surface of the paper situated between the rollers; and the brush removes powder from the surface of the first roller as it rotates, such that the outer surface of the first roller is substantially free from powder when after further rotation it contacts paper situated between the rollers.

14. Apparatus according to claim 13, wherein the outer surface of the first roller is of rubber.

15. Apparatus according to claim 13 or 14, wherein the first roller is supported substantially vertically above the second roller, such that paper passing between the two rollers lies in a substantially horizontal plane.

16. Apparatus according to claim 13, 14 or 15, wherein the second roller is of steel and is provided with a rubber outer coating.

17. Apparatus according to any one of claims 13 to 16, wherein the second roller is mounted such that the top of its outer surface is at the same height as the conveyor system of the paper laminating machine in which it is used.

18. Apparatus according to any one of claims 13 to 17, wherein the surface speed of the second roller is at the same surface speed as the rest of the conveyor system of the paper laminating machine.

19. Apparatus according to any one of claims 13 to 18, wherein the brush is a cylindrical brush, in which the bristles extend radially outwards, and which is rotatably mounted on a support shaft.

20. Apparatus according to claim 19, wherein the brush is mounted substantially vertically above the first roller such that as the brush rotates sequential bristles on the brush are brought into contact with the surface of the first roller.

21. Apparatus according to any one of claims 13 to 20, wherein the brush is rotated in the opposite direction to that of the first roller.

22. Apparatus according to any one of claims 13 to 21, wherein the brush is provided with means for removing powder from its surface.

23. Apparatus according to claim 22, wherein the means for removing powder comprises a suction area through which the bristles of the brush must pass whilst rotating.

24. Apparatus according to claim 23, wherein the suction area is provided with at least one baffle plate which contacts the bristles, causing them to vibrate, thereby removing powder adhered to the bristles.

25. Apparatus according to claim 23 or 24, wherein the suction area is provided with a vacuum system which draws away powder shaken loose from the brush, and comprises a filter to trap powder drawn away from the brush.

26. Apparatus according to claim 23, 24 or, 25, wherein the suction area may be provided with a cowl which extends over the whole of the brush except where the brush contacts the first roller.

27. Apparatus according to any one of claims 23 to 26, wherein the section area is situated substantially vertically above the brush.

28. Apparatus according to claim 24, wherein the baffle plate is situated such that it contacts the bristles of the brush just before the bristles rotate into a vertical position.

29. Apparatus according to any one of claims 23 to 28, wherein the first roller, brush and suction area are mounted relative to each other in such a way as to allow their respective orientation to be finely adjusted, such that varying thicknesses of material passing between the rollers can be accommodated without changing their relative orientation.

30. Apparatus according to any one of claims 13 to 29, wherein a further brush is provided to remove powder from the outer surface of the second roller.

31. Two apparatuses according to any one of claims 13 to 30 arranged in series.

32. Two apparatuses according to claim 31, which have a common second roller which is capable of accommodating both of the two first rollers.

33. A drying drum provided with means for raising the temperature of its outer surface which is also provided with an outer coating of a copolymer of tetrafluoroethylene and hexafluoropropylene.

34. A machine for the lamination of paper which is provided both with apparatus according to any one of claims 1 to 12 and with apparatus according to any one of claims 13 to 32.

35. A machine according to claim 34, wherein the apparatus according to any one of claims 1 to 12 and the apparatus according to any one of claims 13 to 32 are driven by a commonly shared roller.

36. A machine for the lamination of paper which is provided both with apparatus according to any one of claims 1 to 12, and with a drying drum according to claim 33.

37. A machine for the lamination of paper which is provided with apparatus according to any one of claims 1 to 12, with apparatus according to any one of claims 13 to 32 and with a drying drum according to claim 33.

38. Apparatus substantially as hereinbefore described with reference to, and as illustrated in Figures 1 and 2, or Figure 3 of the accompanying drawings.

39. A method of removing loose anti-set-off powder from paper, which method comprises feeding paper between a first roller which supports the paper and a second roller driven by the first roller, which second roller is provided with an outer surface to which powder may adhere, and which second roller is contacted by a brush which removes powder from the outer surface of the second roller.

40. A method of calendaring and subsequently laminating paper, which comprises feeding paper between a third and a second roller, which second roller supports the paper and causes the third roller to rotate, the outer surface of the second roller being at such a temperature that anti-set-off powder on the surface of the paper is substantially removed, followed by feeding the paper between a first roller and the second roller at the same time as an adhesive coated lamina is fed between the first and second rollers, the outer surface of the first roller being at such a temperature as to facilitate the application of the lamina to the paper, and the first roller being driven causing the second roller to rotate.

41. A method of removing a solvent from a lamina coated on one side with an adhesive resin dispersed in a solvent, which method comprises passing the lamina over a drying drum whose outer surface is at a temperature sufficient to evaporate the solvent, and whose outer surface is coated with a copolymer of tetrafluoroethylene and hexafluoropropylene.