GB2250237A

GB2250237A - Printing

Info

Publication number: GB2250237A
Application number: GB9026078A
Authority: GB
Inventors: Hugh Raymond Webb
Original assignee: Folders Galore Ltd
Current assignee: Folders Galore Ltd
Priority date: 1990-11-30
Filing date: 1990-11-30
Publication date: 1992-06-03
Anticipated expiration: 2010-11-30
Also published as: GB2250237B; GB9026078D0

Abstract

An image is printed on a sheet (20) of material or other article by the application of pressure and/or heat to selected areas of a frosted or otherwise rough surface (22) of an article to reduce or remove the roughness of that surface (22) in those areas. The image (26) is created by the resulting contrast in the degree of roughness or smoothness in the selected areas relative to the surrounding areas (22) of the article. <IMAGE>

Description

Printing The present invention relates to a method of printing an image on a sheet of material or other article, and an article bearing an image printed by such a method.

Hitherto one such method has comprised foilblocking. This involves the use of a foil sandwiched between the die of a blocking-machine and a sheet of material on to which a printed image is to be formed, and thereafter applying pressure and heat to selected areas of the foil against the sheet so that the material of the foil adheres to the sheet in selected areas only.

Such a method suffers the disadvantage that a foil has to be interposed between the die and the sheet, and it also renders it difficult to create a subtle image.

In another method of printing, called embossing or hot embossing, a male die, with a projection in the form of a mirror image of what is to be printed, is urged towards a female die, with a recess in the form of what is to be printed, a sheet, onto which the image is to be printed, being sandwiched between the male and female dies.

This requires some sort of female die as well as a male die.

In yet another form of printing, called debossing, a recessed image is formed, but this still requires some sort of female die.

The present invention seeks to provide a remedy to at least one of these disadvantages.

Accordingly the present invention is directed to a method of printing an image on a sheet of material or other article, comprising the application of pressure and/or heat to selected areas of a frosted or otherwise rough surface of an article to reduce or remove the roughness of that surface in those areas, so that the image is created by the resulting contrast in the degree of roughness or smoothness in the selected areas relative to the surrounding areas of the article.

The article is preferably a sheet of material, and the material may comprise polyvinyl chloride (PVC).

A printing effect which is particularly pleasing to the eye is obtained if the PVC material is clear, and more so if the sheet material is smooth on one side and sandgrain embossed on the other, with the selected area being on the sandgrain embossed side of the sheet, and the degree of application of pressure and/or heat is such as to render those selected areas smooth, the originally smooth side remaining smooth. This therefore removes the frosting of the sheet in those selected areas, which may be in the form of graphics, a business logo, a name, words, or numbers, or any combination of any of these sorts of image.

The most useful sheet of material for bearing such an image comprises flat, rigid, 240 micron thickness, glossy PVC, with one-sided sandgrained embossing, although the preferred thickness is actually within a range of values from 140 microns to 300 microns, and the invention may use sheets or other articles of thickness outside this range.

The application of pressure and/or heat to selected areas may be effected by means of a foil-blocking machine without the use of an actual foil, or by means of an embossing machine with a flat bed in place of the female die.

Heat may be applied by the use of a die which is heated to a temperature of l00#C, for example, although the temperature may be anywhere in the region of 50 C to 300 C, or even beyond this range.

The pressure applied may be for example of the order of 4 tons per square inch, but may be anything in the region of 1/3 of a ton to 10 tons per square inch, and possibly even beyond this range.

Finally, the dwell time during which such pressure and/or heat is applied may be 0.5 seconds, or possible anywhere in the region of 0.01 second to 5 seconds, or even beyond this range.

It will be appreciated that a whole range of values of pressure, temperature and dwell time may be selected, provided the product of all three is somewhere in the region of the value given by the preferred values quoted in the foregoing three paragraphs.

It will further be appreciated that it would be possible to use a mechanically or an hydraulically operated machine or a hand operated machine, although it is likely that with the latter the dwell time would be longer.

One machine which may be used in the present invention is a 1971 Heidelberg cutting and creasing platen provided with foil-blocking means, without a foil.

The present invention extends to a sheet or other article of material bearing an image printed by a method in accordance with the present invention.

The present invention also extends to a folder comprising such a sheet.

An example of a method of printing an image on a sheet of material, in accordance with the present invention, and a sheet bearing such an image, will now be described with reference to the accompanying drawings, in which; Figure 1 is a diagrammatic partly cross-sectional view of apparatus on which has been lain such a sheet, for performing such a method; Figure 2 is a like view with a part of the apparatus engaging the sheet; Figure 3 is a cross-sectional view of a sheet bearing a printed image resulting from the method shown in Figures 1 and 2; and Figure 4 shows a further sheet with a modified printed image produced by a method in accordance with the present invention.

Figure 1 shows in diagrammatic form an hydraulically operated foil-blocking machine, the machine comprising a bed 10 having a flat smooth upper surface 11 and a die 12 mounted at the lower end of a piston rod 14 of a piston and cylinder ram 16 fixed in relation to the bed 10 by support means 18.

Whilst the die 12 has been shown in Figure 1 diagrammatically as a simple rectangle, it will be appreciated that its lower surface will have the form of the image which is to be printed.

The die 12 is provided with a heating element 19.

Lain on the bed 10 is a sheet 20 of flat, rigid, 240 micron thickness, clear glossy extruded polyvinyl chloride, with one-side sandgrain embossing. The sandgrain embossed surface 22 is uppermost in Figure 1, and the other side 24 of the sheet 20 is smooth. With the die 12 heated to a temperature of approximately 1000C by means of the heating element 19, the piston and cylinder ram 16 is operated so that the die 12 descends downwardly on to the sheet 20 and exerts a force thereon of approximately 4 tons for every square inch of image to be printed. This pressure is maintained for a dwell time of about i second whereafter the ram is switched to lift the die 12 from the sheet 20.

The resulting image 26 on the sheet 20 is shown in Figure 3, from which it can be seen that the surface of the image is smooth, so that the frosting has been removed in the selected area of the sheet.

It will also be seen that, as a result of the pressure applied by the die 12, this image is sunken a little into the sheet so that the image is recessed, with the reverse side 24 of the sheet remaining flat and smooth in view of the flat smooth upper surface 11 of the bed 10.

With a lower pressure and a higher temperature, such recessing would be slight, and the selected area would be distinguished substantially only by being smooth as opposed to rough, with substantially no recessing, as shown at 28 in Figure 4.

Many variations and modifications to the illustrated method and product will readily occur to the reader familiar with the art of printing without taking it outside the scope of the present invention. To give one example only, the pressure may be applied by means of a hand-operated lever mechanism rather than by a ram. In such a case, the dwell time may be considerably longer, perhaps up to 3 or 4 seconds, to allow for a lower pressure applied to the sheet of material.

Claims

1. A method of printing an image on a sheet of material or other article, comprising the application of pressure and/or heat to selected areas of a frosted or otherwise rough surface of an article to reduce or remove the roughness of that surface in those areas, so that the image is created by the resulting contrast in the degree of rougness or smoothness in the selected areas relative to the surrounding areas of the article.

2. A method of printing an image according to claim 1, in which the article is a sheet of material.

3. A method of printing an image according to claim 2, in which the material comprises polyvinyl chloride (PVC).

4. A method of printing an image according to claim 3, in which the PVC material is clear.

5. A method of printing an image according to claim 3 or claim 4, in which the sheet material for bearing such an image comprises a flat, rigid, glossy PVC, with onesided sandgrained embossing, and with a thickness in a range from 140 microns to 300 microns.

6. A method of printing an image according to claim 5, in which the thickness is 240 microns.

7. A method of printing an image according to any preceding claim, in which the sheet material is smooth on one side and sandgrain embossed on the other, with the selected area being on the sandgrain embossed side of the sheet, and the degree of application of pressure and/or heat is such as to render those selected areas smooth, the originally smooth side remaining smooth.

8. A method of printing an image according to any preceding claim, in which the application of pressure and/or heat to selected areas is effected by means of a foil-blocking machine without the use of an actual foil.

9. A method of printing an image according to any one of claims 1 to 6, in which the application of pressure and/or heat to selected areas is effected by means of an embossing machine with a flat bed in place of the female die.

10. A method of printing an image according to any preceding claim, in which the heat is applied by the use of a die the temperature of which is in the region of 500C to 300 C.

11. A method of printing an image according to claim 10, in which the temperature of the die is 1000C.

12. A method of printing an image according to any preceding claim, in which the pressure applied is in the region of 1/3 of a ton to 10 tons per square inch.

13. A method of printing an image according to claim 12, in which the pressure applied is 4 tons per square inch.

14. A method of printing an image according to any preceding claim, in which the dwell time during which such pressure and/or heat is applied is in the region of 0.01 seconds to 5 seconds.

15. A method of printing an image according to claim 14, in which the dwell time is 0.5 seconds.

16. A method of printing an image according to any preceding claim, in which a mechanically or an hydraulically operated machine or a hand operated machine is used to apply pressure and/or heat.

17. A method of printing an image according to claim 16, in which the machine used is a 1971 Heidelberg cutting and creasing platen provided with foil-blocking means, without a foil.

18. A method of printing an image substantially as described herein with reference to the accompanying drawings.

19. A sheet or other article of material bearing an image printed by a method in accordance with any preceding claim.

20. A folder comprising a sheet as claimed in claim 17.