AU700208B2 - Improved thermal laminating apparatus - Google Patents

Description

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AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT St r 94, 9 9 999* a

ORIGINAL

99« 9* a 9 9 04 9 4 9 9 Name of Applicant: Actual Inventor: Address for service G. HUDSPETH PTY. LTD.

Ray Elliott in Australia: CARTER SMITH BEADLE 2 Railway Parade Camberwell Victoria 3124 Australia Invention Title: IMPROVED THERMAL LAMINATING APPARATUS Details of Associated Provisional Application: PM4441 filed 11 March 1994 The following statement is a full desciption of this invention, including the best method of performnning it known to us -2- The present invention relates to an improved laminating apparatus for making a laminate from transparent film material and a substrate such as a sheet of paper or other material requiring a protective layer. In particular, although not exclusively, the invention relates to a thermal laminating apparatus in which the substrate is encapsulated between two layers of transparent plastic film material having thermally activated adhesive provided on the side of the film material facing the paper or other material to be protected.

In conventional thermal laminating apparatus, two layers of plastic film are drawn from rolls thereof. The plastic film has a coating of thermally activated adhesive on one side thereof. Both layers of film are drawn over respective curved heating bars with the adhesive coating facing outwardly to heat the adhesive coating.

The layers are then drawn through a pair of nip rollers. The substrate paper, or I other material to be protected is placed in the nip defined by the two layers of film t and is thereby drawn trtrough the nip rollers with the two layers of film to form the laminated product. An auxiliary pair of nip rollers downstream of the first mentioned nip rollers are driven at a slightly faster speed (in practice about 2-3%) in order to stretch the film and product a flat laminate free of wrinkles and other imperfections. To further aid in producing a smooth laminate, one or more idler rollers may be located between each film roll and the associated heater bar to guide 20 the film and maintain film tension.

In conventional laminating apparatus, the apparatus is configured so that the substrate is passed through the apparatus in a generally horizontal manner. In such a configuration, at least one of the idler rollers is usually located unLdrneath the heater bars. This makes the apparatus difficult to load and there is a risk of burning the operator's hands on the heater bars in the process of loading and feeding the film 9 around the idler roller. These difficulties therefor place a restriction on the permissible location of the idler roller. If the idler roller is located too far rearwardly of the heater bars then the apparatus is very difficult to load and feed the film around the idler roller. A further difficulty created by the configuration of conventional laminating apparatus is the small distance provided between the holder

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1 1 I9 BGC'JHI079A.RSI 2 Navesber -199 -3for the film roll and the heater bars. To ensure adequate tension of the film is maintained, generally the distance between the film roll and the heater bars is minimized. This makes the operation of loading a new film roll into the apparatus and feeding the film around the idler rollers, heater bars and through the nip rollers very awkward and hazardous.

In known laminating apparatus, it will be appreciated that each of the layers of film are drawn over the external curved surface of respective heater bars which are stationary. This is known to cause scratching of the film which is undesirable in the final laminated product. One known method of avoiding the problem of scratching is to heat the nip rollers themselves. However, this method has been shown to be infeasible in practice. In order to impart sufficient heat to the film, irp. ,c cal large rollers are required. Alternatively, if the problem of large rollers is to be avoided, the heated nip rollers must turn slowly in order to impart sufficient heat to the film. Such slow speeds have also been found to be impractical.

An alternative method of avoiding scratching is to have two pairs of heated rollers including a pair of preheating rollers and a pair of heated nip rollers. This has also been found to be infeasible in practice due to the large number of rollers required considering that the apparatus already includes auxiliary rollers and idler rollers.

20 It is therefore an object of one aspect of the present invention to provide an improved laminating apparatus which overcomes or at least ameliorates the problem of loading and feeding film material into the laminating apparatus.

It is a further objection of a second aspect of the present invention to provide an improved laminating apparatus to prevent scratching or scoring of the film as it traverses the apparatus.

In accordance with a first aspect of the present invention there is disclosed a laminating apparatus for applying at least one side of a substrate with a layer of protective film material drawn from a first film roll, the film material of the type having thermally activated adhesive on one side thereof, the apparatus including: a heat source for heating the adhesive;

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ji; n o BGCIH 141T.RSI Imaabcr 1M n il y I Y -4a pair of pressure rollers for pressing the layer of film material to the substrate; a guide means for guiding the film material; a support structure providing a mounting for at least the pair of pressure rollers; a slide means slidable relative to the support structure in the direction transverse to the axial direction of the pressure rollers between an operative position and a loading position wherein the guide means is mounted on the slide means.

Suitably the slide means will run along guides provided in the support structure. Preferably, these guides are in the form of runners provided on opposite side walls of the support structure. The slide means may comprise parallel spaced plate members joined by joining bars to define more or less a drawer-like configuration. The apparatus may be further provided with stops to define the operative position and the loading position of the slide means. Preferably, the stops are in the form of projections extending from the side walls of the support structure, each projection engaging with a cut-out portion provided in the plate members of the slide means. Furthermore, the slide means may be altogether removable from the apparatus.

The heat source may be in the form of heated bars or platens having an 20 arcuate surface over which the film material is drawn. Preferably there are two such a bars or platens, for heating two layers of film material which are applied to each side of the substrate. The heat source may be mounted between the side walls of the support structire. Alternatively, the heat source may be mounted on the slide means so that when the slide means is moved to the loading position, the heat source is moved away from the pressure rollers. This provides improved access to the pressure rollers for cleaning or other servicing thereof.

The pressure rollers are journailed to the support structure. Preferably both pressure rollers are driven at the same speed by a motor.

The slide means may also biKprovided with support means for supporting the first film roll. Such support means may take the form of aligned slots to receive the i E.O..Wl..CAP .*10 Mac1 99 7 ends of the film roll. Second support means may also be provided for supporting a second film roll. The second support means is preferably located on the support structure. Preferably, the second support means also takes the form of aligned slots provided in the side walls of the support structure.

The guide means may be in the form of an idler roller. The idler roller may bejournalled for rotating movement in the plate members of the slide means. Two or more of such idler rollers may be provided in the slide means. Further idler rollers may also be journalled in the support structure to tension and guide the film material from the second film roll.

In accordance with a second aspect of the present invention there is disclosed a laminating apparatus for making a laminate from a substrate and a layer of protective film material applied to least one side of the substrate, the film material being of the type which is drawn form a roll and which has thermally activated adhesive on one side thereof, the apparatus including: a pair of pressure rollers for pressing the layer of film material to the substrate; support means for supporting the roll of film material; guide means for guiding the film material, at least one of the guide means and the support means being disposed such that in use, the film traverses an arcuate path 20 defined by part of the periphery of one of the pressure rollers and the a least one of the guide means and support means prior to passing between the pressure rollers and a substantially straight path prior to traversing the arcuate path; a radiant heating means for providing radiant heat to the film material to t thermally activate the adhesive on the film, the radiant heating means extending 25 along and spaced from the arcuate path and the substantially straight path.

In a preferred form of the invention, the radiant heating means includes a :"Ii :curved portion and a substantially planar portion, both portions extending along and paced from the film as the latter traverses said paths.

It is envisaged that the film material will traverse a substantially straight path prior to the arcuate path around the roller. This can be set up by spacing the guide GJI- kt 2Nve 1 GC-JHlUTOa-( S l 2Nrlervw lw 9 lj i N, 0* 0 *0

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0 0 0 0 09 *0 00 000 9000 0 0000 0 00000* 0 0 *0 00 0 00 0 0 .000 0* 0 09 00 Ak.1 0 90000* 0 9 09 0 00 ~0 -6means from the pressure roller. It is therefore desirable to extend the radiant heating means to extend adjacent and spaced from a portion of the straight path which is traversed by the film material. This ensures that the film material is heated along a longer path ensuring effective heating of the film material and therefore faster operation of the apparatus.

The radiant heating means may be in the form of discrete heating members or may be a continuous member, For instance, the radiant heating means may take the form of a series of spaced heating bars arranged in a curve adjacent to the arcuate path, Alternatively, the radiant heating means may take the form of a curved plate. The plate may be heated, by conductors or elements embedded in the plate or located behind the plate. To increase the effectiveness of heat transfer, the curve(.' surface of the plate may be provided with corrugations or serrations or be fluted to increase the surface area thereof. In a preferred form, the radiant heating means takes the form of a hollow section, such as an extruded section, with the curved plate defining a concave periphery of the section.

It is preferred that the apparatus also includes a second guide means for guiding a second layer of protective film material in a second arcuate path defined by at least part of the periphery of the outer pressure roller prior to passing between the pressure rollers and a second substantially straight path prior to traversing the 20 arcuate paths.

IIt is also preferred to have a second heating means including a curved portion and a substantially planar portion, the curved portion extending along and spaced from the second arcuate path, the substantially planar portion extending along and spared from the second substantially straight path. Thus two layers of film. can be 25 -applied on either side of the substrate in a single operation.

In order, that the invention is more readily understood, some embodiments thereof wvill now ,be described by way of example, with reference to the drawings in -which: Fig. 1 is a schematic cross-sectional 'view of a laminating apparatus in accordance with a first preferred embodiment of the invention; 2 ?&we=ka 1t 6a Fig. 2 is a schematic cross-sectional view of the laminating apparatus of Fig.

1 in a loading position; Fig. 3 is a schematic cross-sectional view of a laminating apparatus in accordance with a second preferred embodiment of the present invention; Fig. 4 is a schematic cross-sectional view of the laminating apparatus of Fig.

3 in a loading position; Fig. 5 is a schematic cross-sectional view of a laminating apparatus in accordance with a third preferred embodiment of the present invention; Fig. 6 is a schematic cross-sectional view of a laminating apparatus in accordance with a fourth preferred embodiment of the present invention; and Fig. 7 is a cross-sectional view of the preferred form of a heating bar.

As shown in Fig. 1, the thermal laminating apparatus 10 comprises a pair of driven nip rollers 12, 14 anJ a pair of heater shoes 17, 18. Transparent films 19, S09 0a«4 o 449 S9* 4 a f 9 e 0 BGC8JuIMmO4S79 2 vNivye!a 19n -7both having thermally activated adhesive on one side thereof pass over respective heater shoes 17, 18 with the adhesive side facing outwardly. As the transparent films 19, 20 pass over the heater shoes 17, 18 respectively, the adhesive is softened or melted and the films 19, 20 are progressively drawn towards each other. The driven nip rollers 12, 14 draw the films 19, 20 through the apparatus as well as pressing the films 19, 20 together. A substrate such as a photograph or other printed material is inserted in the nip between the films 19, 20 so that the films 19, 20 are sealed to either side of the substrate 22 when passing through the nip rollers 12, 14.

Preferably, the films 19, 20 are wider than the substrate 22 so that the films 19, form a sealed border around the substrate 22. Downstream of the nip rollers 12, 14 is an auxiliary pair of nip rollers (not shown) driven at a slightly faster speed than o ensure that the laminate produced is flat and free of wrinkles.

Nip rollers 14 are journalled between opposite side walls of a support structure (not shown) of the laminating apparatus 10. The heating bars 17, 18 are 9 *9 also secured to the opposite side walls. Two aligned projections 24 also extend from i the opposite side walls of the support structure. These projections 24 act as stops as will be explained. Within the support structure is a slide means which is operable to slide transversely to the longitudinal direction of the nip rollers 12, 14 and the 20 heater bars 17, 18. The slide means is comprised of a pair of parallel spaced plate members 26 joined by two or more joining rods 28. Each of the plates 26 has a cut-out defining edges 29, 30. These edges 29, 30 engage with the stop member 24 to define the limits of sliding movement permissible by the slide means. The apparatus 10 is shown in the operative position in Fig. 1 with the siop 24 abutting the edge 29.

The plates 26 defining the slide means also have aligned slots 34 for supporting the roll 36 from which the film 20 is unwound. An idler roller 38 is also journalled to the slide means. The idler 38 guides the film 20 from the roll 36 in a taut manner to ensure that the film 20 passes smoothly over the heatcr means 18 and through the nip rollers 12, 14. Film 19 is drawn from a roll (not shown) above rcP

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-8the nip rollers 12, 14. An idler roller may also be provided to ensure smooth flow of film 19.

It will be noted from Fig. 1 that film 20 in passing around idler roller 38 traverses through an angle of more than 27O*. Further, the location of the idler roller 38 is below the heater bar 18. However, in Fig. 2 the slide means is drawn out to a loading position in which the stop 24 abuts against the edge 30 of each of the side plates 26. In this position, the idler roller 38 is no longer underneath the heater bar 18 so that feeding of the film 20 around the idier roller 38 and through the nip rollers 12, 14 is made easier. Furthermore, the slots 34 defining the support for the roll 36 are spaced further away from the heater bars 17, 18 than in the operative position so that ample room is provided for loading a new roll of film into 49.,0 0.the apparatus 0 6 The presence of edge 30 abutting against stop 24 is a safety feature which

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limits withdrawal of the slide means so that the slide means cannot be accidentally dropped and cause injury to the operator. The maximum amount of withdrawal of the slide means is determined so that the weight of a new roll will not cause the laminating apparatus as a whole to over-balance and topple over. The slide means V may also be removable from the laminating apparatus 10 altogether by tilting the outer end of the slide means upwardly in a manner similar to removing a drawer from its runners.

Figs. 3 and 4 illustrate a second preferred embodiment of the laminating apparatus 40 which is in many respects similar to the embodiment shown in Figs.

1 and 2 and like numerals represent like parts. However, each of the side plates 26 include supporting portions 43 to provide support for the heater bars 45, 46 which are mounted between the side plates 26. Thus, the heater bars 45, 46 will also move with thp, slide means. Fig. 3 illustrates the slide means in the operative position whereas Fig. 4 illustrates the slide means in the extended or loading position with the heater bars 45, 46 spaced some distance from the nip rollers 12, 14. This provides may access to~ the. nip zollers 12, 14 for cleaning thereof or for loading of the film.

W UNC& -9 C 4-- A _l 4 I II. I -9o pr 4a 4 4~ i4 4 Furthermore, the slide means is removable from the laminating apparatus When the slide means is removed, the apparatus 40 is left with the nip rollers 12, 14, the roll support (not shown) located thereabove and idler 48. The apparatus may then be used to produce laminate from film material having an adhesive coating which is pressure sensitive rather than heat activated. Such film material is applied to substrates which are sensitive to heat. The versatility of the apparatus 40 is therefore increased by having a removable slide means.

Fig. 5 illustrates a third preferred embodiment of the laminating apparatis which is in many respects similar to the embodiments shown in Figs. 3 and 4 and like numerals represent like parts. In the laminating apparatus 50, additional idlers 51, 55 are journalled between the side plates 26 of the slide means. As film 20 is unwound from the roll 36 it passes around idler 55, along a top plate 59 of the slide means, around idler 51 and around idler 38 as before. As the article to be laminated travels above the plate 59, movement of the article is assisted by movement of the film 20 over the plate 59. The inclusion of the additional idlers 51, 55 assist with further tensioning of the film through the apparatus 50 to ensure that the final product is smooth and free of wrinkles. The laminating apparatus 50 is also provided with an additional idler 60 to provide tension to film 19.

Fig. 6 illustrates an additional preferred embodiment of the invention, similar 20 to Fig. 3 and therefore like numerals represent like parts. However, the laminating apparatus 70 shown in Fig. 6 includes additional idlers 72, 73, both of which are journalled between opposite side walls of the support structure. The apparatus is also operated in a different manner in that film 19 does not travel around the external periphery of heater bars 45 and 46 as with previous embodiments. Instead, film 19 after passing around idler 72, passes around nip roller 12 and then between nip rollers 12, 14 to form the final product. Similarly, film 20 after being unwound from roll 36 travels around idler 38 and then idler 73 to then pass around nip roller 14 and between the pair of nip rollers 12, 14. Therefore, instead of the external periphery of heater bars 45, 46 providing direct heat to the films 19, 20, heat is radiated from the inner concave surfaces 78, 79 of the heating bars 45, 46. In this 21

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TTG.M04W9.CAP 10 Mach 1995 way, the chance of scratching or burning or other deteriorations of the films 19, is minimized by avoiding direct contact with the heater bars 45, 46. Instead, as films 19, 20 no longer slide over stationary surfaces, the chance of scratching is minimized.

It may also be appreciated that heater bars 45, 46 may be designed to extend a substantial distance between. nip rollers 12, 14 and the idlers 72, 73. This increases the distance over which the films 19, 20 are heated to thereby increase the effectiveness of the laminating apparatus Fig. 7 illustrates a preferred form of such a heating bar 80. The heati bar 80 is in the form of an extruded aluminium section iaving a curved nose portion 82 to extend around the associated nip roller and tail portion 84 which extends some way betwcen Ile associated nip roller and the associated idler, heating the film as it approaches the associated nip roller. The heating bar 80 is hollow and includes three holders 85 for the heating elements. The remainder of the internal space may be filled with insulating material. The internal periphery of the heating bar 80 has serrations 86 to increase the surface area and improve heat transfer from the heating bar 80. Additionally, the outer periphery of the heating bar 80 may be provided with insulating material such as foam silicone rubber. The insulating material may be glued to the heating bar 80. Alternatively, the insulating material may have beads 20 receivable in recesses 88 provided on the external periphery. It is envisaged that two such heating bars 80 will be utilized to extend adjacent to both of the nip rollers.

Two heating bars may be joined adjacent respective nose portion 82 to form an integral heating bar.

Q 6 C 4 ro oo i p« 3Ci:i1-0479 oRSl 2 November 1998

Claims (4)

1. A laminating apparatus for making a laminate from a substrate and a layer of protective film material applied to at least one side of the substrate, the film material being of the type which is drawn form a roll and which has thermally activated adhesive on one side thereof, the apparatus including: a pair of pressure rollers for pressing the layer of film material to the substrate; support means for supporting the roll of film material; guide means for guiding the film material, at least one of the guide means and the support means being disposed such that in use, the film traverses an arcuate path defined by part of the periphery of one of the pressure rollers and the at least one of the guide means and support means prior to passing between the pressure rollers and a substantially straight path prior to traversing the arcuate path; a radiant heating means for providing radiant heat to the film material to thermally activate the adhesive on the film, the radiant heating means extending along and spaced from the arcuate path and the substantially straight path. *4 4

2. The laminating apparatus as claimed in claim 1 wherein the radiant heating means includes a curved portion and a substantially planar portion, both proportions 4 *44 extending along and spaced from the film material as the latter traverses said paths. 20 3. The laminating apparatus of Claims 5, 1 or 2 wherein the radiant heating means has a generally concave surface provided with corrugations or serrations to increase the rate of heat radiation therefrom. 4

4. The laminating apparatus as claimed in anyone of claims 1-3 further, comprising: a second guide means for guiding a second layer of protective film material o BGCJH:010479.RS 2 November 1998 i

12- in a second arcuate path defined by at least part of the periphery of the other pressure roller prior to passing between the pressure rollers and in a second substantially straight path prior to traversing the arcuate path; and a second heating means including a second curved portion and a second substantially planar portion, the second curved portion extending along and spaced from the second arcuate path, the second substantially planar portion extending along and spaced from the second substantially straight path. The laminating apparatus substantially as hereinbefore described with reference to Fig. 6 or as modified by Fig. 7. DATED: 2 November 1998 CARTER SMITH BEADLE ~Patent Attorneys for the Applicant: G HUDSPETH PTY LTD BG H:#09RS 2 mber 199 o 4 4 8 i i i if a i; ii: .,i ABSTRACT A laminating apparatus (10) is disclosed for producing a laminate comprised of a substrate (22) with a layer of protective film material (19, 20) applied on both sides thereof. The film material (19, 20) is of the type having thermally activated adhesive on one side thereof. The apparatus (10) includes a heat source (17, 18) for heating the adhesive and a pair of pressure rollers (12, 14) for pressing the layers of film material to the substrate Guide means (38) are also provided for guiding the film material (20) through the apparatus Further, a support structure provides a moun'ing for the pressure rollers (12, 14) and a slide means (26) is slidable relative to the support structure in a direction transverse to the axial direction of the pressure rollers (12, 14). The guide means (38) is mounted on the slide means. M S "flHO.'IlGgOmCPA 10 1995