Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE I NVENTI ON
This invention relates to a screen material having a
fineness of at least 250 mesh and to a method of printing
materials by means of this screen material.
For printings for which great detail fineness and detail
sharpness are desirable, screen material is known to be used in
the form of a woven polyester gauze, said polyester gauze
meeting the requirments of the fineness desired.
Said known screen material presents the drawback that at all
times it has to be kept in store under tension mounted on frames.
This requires large storage facilities, since a particular screen
material which, for instance, is not being used for a long time,
must nevertheless be stored in the pretensioned condition on a
frame.
Another drawback is that, after providing the woven
polyester gauze with holes, this gauze loses its dimensional
stability, thus precluding the possibility of meeting the
requirments applicable to a particular printing. A further
drawback is that the known screen material does not very well
assume its original condition after having been used, so that
when using such screen material the quality of the product being
printed greatly decreases after a relatively short period of
time.
Still another drawback i8 that cross threads and weft
threads of the woven polyester gauze are not anchored with each
other, so that, when using a screen having screen openings of 400
mesh, it frequently occurs that a large number of openings have
dimensions that differ from those desired.
Last, there is an important drawback in that rounded threads
are used for said 6creen materials, as a result of which the
permeability to material passing through the screen openings
strongly depends upon the thickness of the threads from which the
polyester gauze is made.
SUMMARY OF THE INVEN~ION
It is now the object of the invention to provide a screen
material which does not have said drawbacks and which is
particularly we'1 suited for printings to be performed with great
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detail sharpness and detail fineness, without the need for said
screen material to be stored in a pretensioned condition on
frames, thus making it possible to gain considerable savings in
terms of storage 6pace requirements.
In addition, said screen material retains its dimensional
stability and so provides for a 6ubstantially increased operation
life.
According to the invention, a screen for printing, or the
like, is provided which comprises a ~creen skeleton of the type
having a fine mesh at least one layer of metal electrolytically
deposited on said skeleton; the screen having fineness of between
250 and 1000 mesh; the screen having a top surface and a bottom
surface, the skeleton being located relatively close to the
bottom surface and relatively remote from the top ~urface; the
mesh openings of the screen having each a cross-sectional area
which gradually increases in the direction from said bottom
surface to said top surface.
In another aspect of the invention, a method is provided for
printing materials said screen material being formed by a screen
having the following features: the screen material includes a
screen 6keleton of the type having a fine mesh; at least one
layer o~ metal has been electrolytically deposited on said
skeleton; the screen material has the finenes6 of between 250 and
1000 mesh; the screen material has a top surface and a bottom
surface, the s~eleton being located relative~y close to the
bottom surface and relatively remote from the top surface; the
mesh openings of the screen material have each a cross sectional
area which gradually increases in the direction from said bottom
surface to said top surface.
When using such a screen, printed products are obtained
which have excellent propertiee, al~o when such screens are used
over an extended period of time.
It is quite surprising that it is possible to form metal
screens having such a fineness.
With particular advantage, the upper side of the screen
opening has a surface which is larger than the lower side of the
screen opening. Such type of screen presents excellent
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properties.
Quite effectively, the screen opening is defined by curved
walls extending from the lower side of the screen opening to the
upper side of the screen opening as this provides excellent
printing results.
The screen material is very effectively obtained by
electrolytic deposition of a metal upon a screen skeleton, the
bath ~olution passing, at least during a part of the electrolytlc
depositing time, through the openings in the screen skeleton
connected as the cathode.
The forced movement of the bath solution through the
openings in the screen skeleton results in screens being formed
which have the aforesaid openings and afford the forming of a
relatively rigid screen material that has a very great fineness
as well.
With particular advantage, the screen material consists of a
cylindrical screen, which type of screen has not been available
so far with the fineness as indicated. It goes without saying
that this makes it possible to produce in a very simple manner
printings having the detail fineness and great detail sharpness
as desired.
The invention further relates to a method for printing
materials while using a screen material having a fineness of at
least 250 mesh, wherein a metal screen is used which was obtained
by electrolytic deposition of at least one metal upon a screen
skeleton and having a fineness of 250 to 1000 mesh.
In the method of the invention, printing effectively
proceeds by using a screen obtained by electrolytic deposition,
in which case at least during part of the electrolytic depositing
time the bath solution flows through the openings in the skeleton
screen.
Other attendant advantages will be more readily appreciated
as the same becomes better understood by reference to the
following detailed description and considered in connection with
the accompanying drawings in which like reference symbols
designate like parts without the figures.
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DESCRI PTI ON OF THE: DRAWI NGS
FIG. 1 is a view of a screen material according to the
invention;
FIG. 2 is sectional view of a screen material according to the invention; and
FIG. 3 is a view of a cylindrical screen material according to
the invention.
DESCRI PTI ON OF THE PREFERRED EMBODI MENTS
FIG. 1 shows a screen material 1 consisting of a metal
screer. 1 obtained by electrolytic deposition of at least one
metal 2 upon a screen skeleton 3. The screen has a fineness of
400 mesh, so that there are 400 openings 4 per 2,54 cm.
The electrolytic bath as used for depositing said metal is a
well known electrolytic bath containing an organic compound
comprising at least one unsaturated bond which does not belong to
a =C-S=O group such as butyne diol.
FIG. 2 shows more particularly the shape of a number of
openings in the screen. As seen, the free upper side 5 of the
screen opening has a larger area than the area of the screen
opening on the lower side of the screen 6.
The screen opening is defined by the curved walls 3 of the
lands bounding the screen opening 4.
In addition, it is evident that the metal deposited by
electrolytic deposition mainly extends on one side of the screen
~5 skeleton. On the other side of the screen skeleton, only a small
layer thickness 7 of the electrolytically deposited metal has
precipitated. This is more particularly shown in FIG. 2.
The shape of the screen openings is obtained by connecting a
screen skeleton as the cathode and by having the electrolytic
solution flow ln the direction from the cathode to the anode or
in the reverse direction Preferably the direction of flow is
from the cathode to the anode.
The screen according to the invention is particularly well
adapted for printings for which hitherto woven polyester gauze
has been used.
The screen material according to the invention distinguishes
itself very favorably from the woven polyester gauze by the
dimensional stability of the screen materlal used, which results
in the remaining screen material retaining its nondeformable
character when forming the openings in the screen material, the
screen permeability being no longer dependent upon the thickness
of the lands of the screen material by properly selecting the
walls of the screen openings, and, finally, the size of the
screen openings being ensured at all times, also after an
extended period of use, this being in contradistinction to
applications using wo~en polyester gauze.
FIG. 3 shows a cylindrical screen material according to the
invention in the form of a cylindrical screen 1' said cylindrical
screen material being particularly suitable for continuous
printing.
