Printable watermarked papers

Abstract

 A watermarked, coated paper material (10) in sheet form and permitting high-quality print is defined by a base paper (1) having a first surface (2) impressed with a watermark (4), and a substantially flat second surface (3) having a coating (6) and so permitting high-quality print. The paper material is characterized in that the base paper (1), without the coating (6), is of a substance ranging between 70 and 200 g/m²; and in that the watermark (4) is of a marking depth (S2) of over approximately 10% (and preferably ranging between approximately 10% and approximately 30%) of the thickness (S1) of the base paper (1). The paper material according to the invention is therefore much lighter (for a given thickness) than similar known products, and has a clearer, better impressed watermark.

Description

[0001] The present invention relates to high-quality-printable watermarked paper materials.

[0002] As is known, commonly used watermarked paper has the watermark impressed on both sides, and the incisions or depressions forming the watermark result in uneven surfaces which pose serious problems when the paper is to be coated prior to printing. That is, the coating material accumulates in the watermark depressions, and may result in an uneven coating in turn resulting in poor print quality (high print quality normally calls for an extremely even coating surface).

[0003] To eliminate this drawback, it has been proposed to flatten, by calendering, one side of watermarked paper to be coated and printed. However, obtaining a flat enough surface to ensure print of fully satisfactory quality has been found to require considerable calendering pressure, so that the paper as a whole, and not only the surface to be flattened, undergoes severe crushing which, for a given initial substance, greatly reduces the thickness of the paper. Consequently, to obtain paper of a given thickness, heavier starting material must be used. Moreover, calendering greatly reduces the depth, and therefore the definition and quality, of the watermark.

[0004] For all these reasons, currently available coated watermarked paper either poses serious printing problems (due to the watermark being impressed on both sides of the paper), or, if printable, is relatively thick and of relatively high substance with a shallow, poorly defined watermark.

[0005] It is therefore an object of the present invention to provide a paper material designed to eliminate the aforementioned drawbacks. More specifically, it is an object of the invention to provide a watermarked paper permitting high-quality print, while at the same time having a clear, well impressed watermark, and being considerably lighter (for a given thickness) than currently available types of paper.

[0006] It is a further object of the invention to provide a coated watermarked paper material permitting high-quality print, while at the same time being relatively light and having a clearly impressed watermark.

[0007] According to the present invention, there is provided a high-quality-printable watermarked paper having a first surface impressed with a watermark of predetermined pattern; and a second surface opposite said first surface and which is substantially flat; said watermarked paper being characterized by being of a substance ranging between 70 and 200 g/m²; and in that said watermark is of a marking depth of over approximately 10% of the thickness of said watermarked paper.

[0008] More specifically, the watermark is of a marking depth ranging between approximately 10% and approximately 30% of the total thickness of the watermarked paper, and the watermarked paper is of a thickness ranging between approximately 0.05 mm and approximately 1 m, and preferably ranging between approximately 0.1 mm and approximately 0.5 mm.

[0009] According to a further aspect of the invention, the substantially flat second surface of the watermarked paper, opposite the first surface impressed with the watermark, has a coating.

[0010] The invention therefore also relates to a watermarked, coated paper material in sheet form, permitting high-quality print, and comprising a base paper having a first surface impressed with a watermark, and a substantially flat second surface having a coating; the paper material being characterized in that said base paper, without said coating, is of a substance ranging between 70 and 200 g/m²; and in that said watermark is of a marking depth of over approximately 10% of the thickness of said base paper, and preferably ranging between approximately 10% and approximately 30% of the thickness of said base paper.

[0011] Thus, there is provided a watermarked paper which is not only impressed with the watermark on only one surface - while the opposite surface is substantially flat, may therefore be coated, and permits high-quality print - but which at the same time is much lighter (for a given thickness) than currently available types of paper, and has a clearer, better impressed watermark.

[0012] As compared with known types of paper having one watermarked surface and one substantially flat, coated surface, the watermarked paper according to the invention has, for a given thickness, a much lower substance and is therefore much lighter. Known types of paper (obtained by calendering) of the same thickness as the watermarked paper according to the invention have a much higher substance, and the depth of the watermark, as a result in fact of the calendering process, is normally less than 10% of the total thickness of the paper (and therefore poorly defined and totally unsatisfactory for most applications).

[0013] A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a schematic side view of a paper material in sheet form in accordance with the invention;

Figure 2 shows, schematically and with no regard to proportion, an enlarged detail of the Figure 1 material;

Figure 3 shows, schematically, one step in the method of producing the Figure 1 paper material.

[0014] With reference to Figures 1 and 2, a watermarked paper 1, permitting high-quality print, has two opposite, parallel, facing surfaces 2 and 3; surface 2 is impressed with a watermark 4 of predetermined pattern or design and shown schematically by a number of incisions or depressions 5 impressed on surface 2 and defining the markings; while surface 3 is substantially flat and has no marking, as can be seen when held up to grazing light.

[0015] Watermarked paper 1 has a substance ranging between 70 and 200 g/m², and may vary in thickness S1 (depending also on the composition of the watermarked paper): purely by way of example, watermarked paper has been produced with the above substance and ranging in thickness S1 between 0.05 and 1 mm (50-1000 µm). The preferred thickness S1 ranges between 0.1 and 0.5 mm (100-500 µm).

[0016] Whichever the case, watermark 4 is of a marking depth S2 - defined as the depth of incisions or depressions 5 (i.e. of the markings) - of over approximately 10% of thickness S1 of watermarked paper 1. For example, for a thickness S1 of 100 µm, the watermark is at least 10 µm deep, so that, at the markings, the thickness of the watermarked paper is reduced to 90 µm.

[0017] More specifically, marking depth S2 ranges between approximately 10% and approximately 30% of thickness S1.

[0018] Substantially flat surface 3 is a coated surface, i.e. having a coating 6 of any known type. Since surface 3 has no markings, coating 6 may be applied easily and is in turn substantially flat, homogeneous, and uniform, thus permitting high-quality print using any known printing process.

[0019] Watermarked paper 1 thus constitutes a base paper from which to obtain, when coated, a watermarked, coated paper material 10 in sheet form permitting high-quality print and characterized by the presence of base paper 1 described above.

[0020] Watermarked paper 1 and paper material 10 can be produced using substantially known methods, but with certain provisions by which to impart to the watermarked paper and paper material the surprising characteristics described and claimed herein. More specifically, and as shown schematically in Figure 3, a web 11 of paper, produced in conventional manner and supported on a canvas belt 12, is fed to a watermarking unit 13 comprising a marking roller 14 bearing the watermark pattern to be impressed on the paper; a water tank 15 underneath marking roller 14; and two supporting rollers 16. Marking roller 14 exerts a predetermined pressure on the top surface of web 11, at a contact line 17; and the two supporting rollers 16 are located beneath canvas belt 12, inside water tank 15 and on opposite sides of contact line 17.

[0021] Operating in this way, a watermarked paper has surprisingly been obtained having markings only on one surface, while the opposite surface remains substantially flat. At this point, the flat surface of the watermarked paper is coated using any known method, and then printed using any known printing process.

[0022] Clearly, changes may be made to the watermarked paper and to the watermarked, coated paper material as described and illustrated herein without, however, departing from the scope of the present invention.

Claims

1. A high-quality-printable watermarked paper (1) having a first surface (2) impressed with a watermark (4) of predetermined pattern; and a second surface (3) opposite said first surface (2) and which is substantially flat; said watermarked paper being characterized by being of a substance ranging between 70 and 200 g/m²; and in that said watermark (4) is of a marking depth (S2) of over approximately 10% of the thickness (S1) of said watermarked paper (1).

2. A watermarked paper as claimed in Claim 1, characterized in that said watermark (4) is of a marking depth (S2) ranging between approximately 10% and approximately 30% of the thickness (S1) of said watermarked paper (1).

3. A watermarked paper as claimed in Claim 1 or 2, characterized in that the substantially flat said second surface (3) has a coating (6).

4. A watermarked paper as claimed in one of Claims 1 to 3, characterized by being of a thickness (S1) ranging between approximately 0.05 mm and approximately 1 m, and preferably ranging between approximately 0.1 mm and approximately 0.5 mm.

5. A watermarked, coated paper material (10) in sheet form, permitting high-quality print, and comprising a base paper (1) having a first surface (2) impressed with a watermark (4), and a substantially flat second surface (3) having a coating (6); the paper material being characterized in that said base paper (1), without said coating (6), is of a substance ranging between 70 and 200 g/m²; and in that said watermark (4) is of a marking depth (S2) of over approximately 10% of the thickness (S1) of said base paper (1).

6. A paper material as claimed in Claim 5, characterized in that said watermark (4) is of a marking depth (S2) ranging between approximately 10% and approximately 30% of the thickness (S1) of said base paper (1).

7. A paper material as claimed in Claim 5 or 6, characterized in that said base paper (1), without said coating (6), is of a thickness (S1) ranging between approximately 0.05 mm and approximately 1 mm, and preferably ranging between approximately 0.1 mm and approximately 0.5 mm.

Drawing