IES60398B2 - A method of fixing holograms to a sheet material - Google Patents

Description

This invention relates to a method of fixing * holographic images to a sheet material such as paper, for example as an anti-counterfeit measure.

There are two main methods of fixing holograms to paper at the present time. Hot foil stamping entails stamping out the hologram shape from a roll of holographic foil using a hot plate and shape which activates a heat sensitive adhesive and seals the hologram to the paper by pressure and heat. This method is slow and expensive.

Holographic labels are also applied using a conventional label applicator. While this method is fast it is not secure because the adhesive is weak and the holographic label can be removed without difficulty and intact, to be used later to authenticate counterfeit products.

It is an object of the invention to provide a method of fixing holographic images to sheet material which is fast vet permits the use of secure adhesive.

According to the invention there is provided a method of fixing holographic images to a sheet material, comprising drawing a continuous web of the sheet material from a stock of the material, drawing a continuous web of holographic foil from a stock of the ' foil, the foil having holographic images at spaced locations along the length of one surface, applying an s adhesive to the sheet material at spaced locations along the length of one surface such locations corresponding to desired fixing positions for the holographic images. / - 2 1 the adhesive at each location being applied to an area whose shape substantially corresponds to that of the holographic image, bringing the sheet material an foil into contact such that the holographic images are in 5 register with the areas of adhesive, the adhesive contacting the surface of the foil opposite to that bearing the holographic images, drawing the sheet material and foil together past a pressure applying means to cause the foil to adhere to the sheet 10 material in the adhesive areas, and drawing the foil away from the sheet material so that the foil ruptures around the perimeter of the holographic images to leave the latter fixed to the web.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing whose single figure shows an apparatus upon which such embodiment may be performed20 The apparatus shown in the drawing is a conventional high speed collator/mailer machine of the kind manufactured and marketed by Hamilton Stevens of Ohio, USA. A stock of sheet material such as a roll of paper (not shown) upon which holograms are to be fixed is accommodated in a housing 10. The paper 11 is drawn continuously from the roll by a continuous pin band feed 17, the paper having perforated edges which are engaged by the pins of the pin band feed.

Thus the paper 11 emerges from the housing 10 at the point 12, passes around rollers 13 and passes back into the machine at 14 to a tensioner (not shown). The paper re-emerges from the housing 10 at the point 15 and passes round further rollers 16 into contact with the pin band feed 17. The paper then travels on the pin band feed 17 under a W activator 18 and a pressure roller 19, both to be described, and finally emerges from the machine at 20 where it can be stored in fan-fold or reel form. } * Holographic foil 21, likewise perforated at its edges, is simultaneously drawn from a roll 22 by the pin band feed 17. The foil 21 passes around a roller 23 into contact with the paper 11 on the pin band feed, and both are carried under the pressure roller 19. The foil 21 is brought into contact with the paper 11 after the UV activator 18 but before the pressure roller 19. The foil 21 has holographic images on one surface thereof at regularly spaced locations along its length. These images are provided on the surface of the foil 21 opposite to that in contact with the paper 11 on the pin band feed 17, that is, the upper surface of the foil on the pin band feed.

Within the housing 10 an adhesive is applied at regularly spaced locations along one surface of the paper, the locations corresponding to desired positions of the holographic images to be fixed thereto and the adhesive at each location being applied to an area whose shape substantially corresponds to that of the holographic image.

The adhesive may be applied in conventional manner using a so-called stereo or photopolymer plate having the shape of the holographic image. The adhesive is applied to that surface of the paper which is in contact ( with the overlying foil when the two are on the pin band feed 17, that is, the upper surface.

An example of a suitable adhesive is Aquatac D125, a water based dispersion of a carboxylated copolymer, marketed by International Coatings & Adhesives, Dublin. The adhesive has a density of 1.01g/cm3, a particle size of 0.6gm and a pH of 4.0. The adhesive is such that when set it prevents a holographic image from being removed from the paper without damaging one or both of the image and paper.

The relative longitudinal positions of the paper 11 and foil 21 on the pin band feed 17 are adjusted so that 10 when the paper 11 and foil 21 are brought together on the pin band feed 17 at the roller 23 the holographic images on the foil are in register with the areas of adhesive on the paper 11.

Immediately before the paper 11 and foil 21 are brought together the paper 11 bearing the adhesive areas is drawn under the UV activator 18 which reactivates the adhesive, and immediately after the paper 11 and foil 21 are brought together they are drawn past the pressure roller 19. This causes the foil 21 to adhere to the paper 11 in the adhesive areas. The the foil 21 is drawn away from the paper 11 to a take up roll 24, the paper 11 remaining on the pin band feed 17. This ruptures the foil 21 around the perimeter of each holographic image to leave the latter fixed to the paper 11. The foil may be weakened around the perimeter of each holographic image to assist a clean rupture.

Instead of using a holographic foil with perforated edges, one could use a standard holographic tape and rely on the adhesion between the tape 21 and paper 11 on the pin band feed to draw the foil through the machine.

On the machine identified above the method can be carried out at a speed of 12,000 feet per hour.

Claims (5)

1. A method of fixing holographic images to a sheet material, comprising drawing a continuous web of the sheet material from a stock of the material, drawing a - continuous web of holographic foil from a stock of the foil, the foil having holographic images at spaced locations along the length of one surface, applying an adhesive to the sheet material at spaced locations along the length of one surface such locations corresponding to desired fixing positions for the holographic images, the adhesive at each location being applied to an area whose shape substantially corresponds to that of the holographic image, bringing the sheet material and foil into contact such that the holographic images are in register with the areas of adhesive, the adhesive contacting the surface of the foil opposite to that bearing the holographic images, drawing the sheet material and foil together past a pressure applying means to cause the foil to adhere to the sheet material in the adhesive areas, and drawing the foil away from the sheet material so that the foil ruptures around the perimeter of the holographic images to leave the latter fixed to the web.

2. A method as claimed in claim 1, wherein the adhesive is such as to prevent a holographic image from being removed from the sheet material without damaging one or both of the image and sheet material.

3. A method as claimed in claim 1 or 2, wherein the adhesive is a water based dispersion of a carboxylated co-polvmer, the method further including subjecting the adhesive on the sheet material to ultra violet light before bringing the sheet material and foil into contact.

4. A method of fixing holographic images to a sheet material substantially as described with reference to the accompanying drawing.

5. A sheet material having holographic images fixed thereon by the method claimed in any preceding claim.