The present invention relates to high-quality-printable watermarked
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).
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.
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.
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
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.
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.
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.
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.
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.
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.
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).
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.
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.
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).
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.
More specifically, marking depth S2 ranges between approximately
10% and approximately 30% of thickness S1.
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.
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.
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.
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.
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.