GB1586591A

GB1586591A - Method and machine for adhesive coating of film and subsequent laminating to substrate

Info

Publication number: GB1586591A
Application number: GB23095/76A
Authority: GB
Original assignee: Beer M W
Current assignee: Beer M W
Priority date: 1977-09-02
Filing date: 1977-09-02
Publication date: 1981-03-25

Description

(54) METHOD AND MACHINE FOR ADHESIVE COATING OF FILM AND SUBSEQUENT LAMINATING TO SUBSTRATE (71) I, MICHAEL WILLIAM BEER, a British subject of 15 Barrowby Road, Broom, Rotherham, Yorkshire, do hereby declare the invention for which I pray that a Patent may be granted to me and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to method and machine for adhesive coating a film and subsequently laminating this to a substrate.

For example the film may be of synthetic plastics material, while the substrate may be of paper or card or other cellulose material.

With the various known adhesive coating methods and machines - although not necessarily for subsequent laminating to a substrate - accurate control of the coating thickness is all important and has usually been effected by a stationary doctor blade and furthermore, if the coating is adhesive the percentage of solids and hence the adhesiveness is equally important.

However, in the past it has been difficult to apply more than about 40% solids, with the consequent need to remove about 60% of liquid carrier. The adhesive, has been water based or alternatively hydrocarbon or spirit based. Water based adhesives however, only have limited useful applications, such limitations being avoided in the prior art by the use of spirit based adhesives. However, these adhesives introduce fume problems and fire risks, with the consequent need for additional equipment to deal with this. With laminating, there is further introduced a high risk of undesirable chemical solvent/pigment interaction due to the types of solvent used.

Laminating methods and machines are, for example, well known for applying transparent plastics film to a substrate of paper or card carrying printed matter, e.g. a colour picture, photographs etc. which substrate may, for example, be product advertising material in the form of book jackets, record sleeves etc.

Such a substrate is therefore protected by the film, being more resistant to damage and dirt, and hence being more durable.

According to a first aspect of the present invention a method of adhesive coating a film and subsequently laminating this to a substrate, comprises forming a reservoir of a water based adhesive at a nip defined between adjacent peripheries of a first pair of rollers rotatable about parallel, horizontal axes, passing the film through the reservoir and through the nip, adjusting the nip pressure in accordance with the coating thickness required and therefore passing the adhesive coated film, and a substrate required to be laminated, together through the nip of a second pair of rollers, rotatable about parallel, horizontal axes, and the laminated product emerging therefrom.

A further preferred product of this aspect of the invention is the introduction of a stress line laterally across the film after application of adhesive but before being brought into contact with the substrate.

According to a second aspect of the present invention, a machine for applying an adhesive coating to a film and subsequently laminating this to a substrate comprises a first pair of rollers rotatable about parallel longitudinal axes, adjacent peripheries thereof defining a nip, means for feeding the film to the first pair of rollers, means to feed a water based adhesive to a zone above the nip to form a water based reservoir and means to adjust the nip pressure, a second pair of rollers rotatable about parallel longitudinal axes and means for feeding both the coated film and the substrate to the second pair of rollers.

Furthermore, the machine may comprise a laterally extending stress blade to introduce a line of stress across the film.

Thus, the rollers provide a continuously rotatable doctor to control the coating thickness within very close tolerances, the film being loaded into the nip by passage around and peripheral contact with, one roller, the other roller constituting the doctor roller.

With the method used to apply a water based adhesive to a film, some 60 to 80% of solids (resins and polymers) may be applied which apart from giving increased adhesiveness, means that only 40 to 20% of liquid carrier needs to be removed.

The method and machine in accordance with the invention enables successful laminating to be achieved on a wet laminating machine using a water based adhesive. Such an adhesive of course has the fundamental advantage compared with hydrocarbon or spirit based adhesives of being non-toxic, free from attack against inks carried by the base material, which attack results later in delamination tendencies, free from the need to install fume extraction and/or treating equipment and free of fire risk, while likewise enabling the machine to be easily and quickly washed down with water.

The film, for coating and laminating is conveniently in continuous form stored on a reel, and may for instance be orientated polypropylene film. This film may be coated with an adhesive comprising 60% solids (made up of 50% vinyl and 50% Acrylic solids) 21X% plasticiser, balance water, to give a solid coating of 7gm/m2.

The substrate may be fed from a reel or individual sheets thereof may be fed, with the leading edge of one sheet overlapping the trailing edge of a preceding sheet which again assists in achieving successful adhesion and hence a successful laminated product. Individual sheets may be hand loaded onto a feed table e.g.

comprising a plurality of feed tapes driven at variable speed. Preferably, the axis of rotation of one of the second pair of rollers is adjustable to accommodate varying nip pressures required for varying the film and substrate thicknesses.

Such adjustment may be effected by eccentric mounting of the bearings of one of the rollers, e.g. a non-heated roller. A heated roller helps to generate "tack" in the adhesive but its primary function is to overcome a "trapped adhesive" condition where surface finishes, which are virtually impervious to water, of the substrate, can cause distension of the film during the settling and drying period. A heated roller is preferably thermostatically controlled at its required temperature e.g. 50 C to 600 C. The laminated product may be taken up in reel form on a removable take off reel, which in practice may be quickly replaced by an empty reel so as to ensure continuity of operation.

The stress blade ensures that the contact of the adhesive coated film to the substrate occurs at a two-dimensionally straight position i.e.

both the film and substrate are affected by the stress blade. This effect is particularly important where a thin, low fibre strength and stability substrate is being used. When a heavily absorbent substrate requiring relatively more adhesive is used the advantage of the stress blade squeegee effect, without high pressure (e.g. as exists at the second pair of rollers), largely obviates the problems of adhesive being squeezed under the overlapped sheets of substate to contaminate the pinch rollers. The amount of stress may be varied, by varying the blade position, to accommodate varying thickness of paper or board.

The arc of contact of the adhesive coated film over a heated roller in conjunction with the operational speed may be sufficient to remelt or make tacky the adhesive. However, the adhesive coated film may be heated before reaching the second pair of rollers. For example a radiant or tuned radio-frequency heating means may be located adjacent a run of the adhesive coated film which precedes the second pair of rollers. A heated roller may operate at a temperature of 70-750C and is preferably metallic or has a metal surface whereas the non-heated roller is of rubber or has a rubber surface.

Additionally, the laminating machines may be provided with a third pair of rollers adjustable to vary the nip pressure. These may be used for double laminating, or for embossing or slitting.

The invention will now be described in greater detail by way of example with reference to the accompanying drawing which is a diagrammatic side elevation of a coating and laminating machine in accordance with the invention.

In the drawing, the right hand portion A represents a coating portion of the machine, and the left hand portion B represents a laminating portion of the machine.

The coating portion A comprises a pair of rollers 1, 1 A, rotatable about parallel axes 2 adjacent peripheries 3 of the rollers 1 abutting and defining a nip 4 which contains a reservoir 5 of a fluid coating medium, constituted by a water based adhesive. The roller 1 is rubber or rubber covered, while the roller 1A is a metal roller. The reservoir 5 is maintained at the desired level by drop feeding from a head 6 supplied along feed line 7 by a pump (not shown) connected to an adhesive supply tank 8. Spaced from the rollers 1 is a guide roller 9 rotatable about an axis 10 parallel to the axes 2, the roller 9 being located higher than rollers 1, 1 A, so as to give the desired angle of feed for a continuous film 11 to be coated with adhesive, which film is fed in the direction indicated by arrows 12 from a storage reel (not shown) the film being fed into the reservoir 5 around a portion of the periphery of one of the rollers 1, 1A, nip pressure between abutting peripheries of the rollers, 1, 1A, being adjustable by one or both of the rollers 1, 1A, being displaceable in the direction of arrows 13, so as to control the thickness of the coating of adhesive on the film 11 as it emerges at 15 beneath the nip 4. A drip tray 16 is displaceable to cover the tank 8 when it is required to clean the rollers 1, 1A.

The laminating portion B receives adhesive coated film from the coating portion A, the film passing around a guide roller, 17 and thereafter along film track 11. The laminating portion B comprises a second pair of rollers 18, 19, the former being of rubber or rubber covered and the latter being a metal heated roller, both rollers 18, 19 being rotatable about axes 20, 21, parallel to the axes 2, which axes are adjustable with respect to one another so that the nip pressure between their adjacent peripheries 22 may be adjusted. An endless belt 23, extending around guide rollers 24, 25, conveys individual elements of paper or board 26, which it is required to laminate, to the rollers 18, 19, the pressure generated at the nip between adjacent peripheries 22, with the heat ing effect of the heated roller 19, causing lamination and the laminated boards 26 being conveyed beyond the rollers 18, 19 for further process e.g. slitting. Beyond the rollers 18, 19 are a second pair of rollers 27, 28 rotatable about axes 29, 30, parallel to axes 20,21, and adjustable with respect to one another to set the nip pressure required between adjacent abutting peripheries 31. The rollers 27, 28 may be employed to emboss or slit laminated stock emerging from the rollers, 18, 19. Alternatively, the rollers 27, 28 may be employed to effect double laminating, with a second film (not shown) supplied from a second coating portion (not shown) identical to the coating portion A.

In the area between the feed roller 17 and the rollers 18, 19,27, 28, may be located additional heating/drying means, indicated generally at 32, which may or may not be required dependent upon the required speed of operation of the machine, the temperature to which the roller 19 is heated, the arc of contact with the latter etc. A laterally extending stress blade 33 may be located in advance of the laminating rollers 18,19.

Also indicated in the drawing is a possible replacement of roller 19 by a larger diameter roller 34, having a flock covering which may in certain circumstances be required when a particularly even coating is required or when an awkward coating material or substrate is involved. Alternatively the roller 34 may be employed for printing purposes. Also indicated is an associated contact roller 35 and a feed tray 36. The roller 19 may be heated electrically, as may the roller 28.

WHAT I CLAIM IS: 1. A method of adhesive coating a film and subsequently laminating this to a substrate comprising forming a reservoir of a water based adhesive at a nip defined between adjacent peripheries of a first pair of rollers rotatable about parallel horizontal axes, passing the film through the reservoir and through the nip, adjusting the nip pressure in accordance with the coating thickness required and thereafter passing the adhesive coated film, and a substrate required to be laminated, together through the nip of a second pair of rollers, rotatable about parallel, horizontal axes, and the laminated product emerging therefrom.

2. A method as claimed in Claim 1, compris- ing introducing a stress line laterally across the film after application of adhesive but before being brought into contact with the substrate.

3. A method as claimed in Claim 1 or Claim 2, wherein one of the second pair of rollers is heatable.

4. A machine for applying an adhesive coating to a film and subsequently laminating this to a substrate in accordance with the method of any preceding Claim, comprising a first pair of rollers rotatable about parallel longitudinal axes, adjacent peripheries thereof defining a nip, means for feeding the film to the first pair of rollers, means to feed a water based adhesive to a zone above the nip to form a water based adhesive reservoir and means to adjust the nip pressure, a second pair of rollers rotatable about parallel longitudinal axes, and means for feeding both the coated film and the substrate to the second pair of rollers.

5. A machine as claimed in Claim 4, comprising a laterally extending stress blade to introduce a line of stress across the film.

6. A machine as claimed in Claim 4 or Claim 5, wherein one of the second pair of rollers is heatable.

7. A machine as claimed in any one of Claims 4 to 6, wherein the axis of rotation of one of the second pair of rollers is adjustable to accommodate varying nip pressures required for varying the film and substrate thickness.

8. A machine as claimed in Claim 7, wherein the adjustment is effected by eccentric mounting of the bearings of one of the rollers.

9. A machine as claimed in Claim 8, wherein the adjustable roller is a heated roller.

10. A machine as claimed in any one of Claims 6 to 9, comprising heating means located adjacent a run of the adhesive coated film which precedes the second pair of rollers.

11. A machine as claimed in any one of Claims 6 to 10, wherein the heated roller is metallic or has a metal surface.

12. A machine as claimed in Claim 6 and any Claim appendant thereto, wherein the nonheated roller of the second pair of rollers is of rubber or has a rubber surface.

13. A machine as claimed in any one of Claims 4 to 12 comprising a third pair of rollers adjustable to vary the nip pressure.

14. A machine for applying an adhesive coating to a film and subsequently laminating this to a substrate substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ing effect of the heated roller 19, causing lamination and the laminated boards 26 being conveyed beyond the rollers 18, 19 for further process e.g. slitting. Beyond the rollers 18, 19 are a second pair of rollers 27, 28 rotatable about axes 29, 30, parallel to axes 20,21, and adjustable with respect to one another to set the nip pressure required between adjacent abutting peripheries 31. The rollers 27, 28 may be employed to emboss or slit laminated stock emerging from the rollers, 18, 19. Alternatively, the rollers 27, 28 may be employed to effect double laminating, with a second film (not shown) supplied from a second coating portion (not shown) identical to the coating portion A. In the area between the feed roller 17 and the rollers 18, 19,27, 28, may be located additional heating/drying means, indicated generally at 32, which may or may not be required dependent upon the required speed of operation of the machine, the temperature to which the roller 19 is heated, the arc of contact with the latter etc. A laterally extending stress blade 33 may be located in advance of the laminating rollers 18,19. Also indicated in the drawing is a possible replacement of roller 19 by a larger diameter roller 34, having a flock covering which may in certain circumstances be required when a particularly even coating is required or when an awkward coating material or substrate is involved. Alternatively the roller 34 may be employed for printing purposes. Also indicated is an associated contact roller 35 and a feed tray 36. The roller 19 may be heated electrically, as may the roller 28. WHAT I CLAIM IS:

1. A method of adhesive coating a film and subsequently laminating this to a substrate comprising forming a reservoir of a water based adhesive at a nip defined between adjacent peripheries of a first pair of rollers rotatable about parallel horizontal axes, passing the film through the reservoir and through the nip, adjusting the nip pressure in accordance with the coating thickness required and thereafter passing the adhesive coated film, and a substrate required to be laminated, together through the nip of a second pair of rollers, rotatable about parallel, horizontal axes, and the laminated product emerging therefrom.