FR2472417A1 - Vibratory sieve providing electrostatic field - for printing flocked fibres with pattern effect - Google Patents

Abstract

Method of printing with an electrostatic field using flocked fibres or other particulate material employs a vibratory sieve with compartments comprising a series of tubular elements of a non-conducting material, each of which is independent and detachable from the body of the sieve. The lower grid of the sieve is connected to a high tension generator. Patterning effects are achieved by masking part of the sieve and confining the feed of the particulate material to the unmasked areas. A continuous process for applying electrostatically charged material to a substrate and the over-printing of a pattern in relief uses the same apparatus without the need to resort to fixing the material at an intermediary stage. Flocking unit may be introduced into a silk-screen printing system without disturbing its function and avoiding any blockage of the printing frames with the dispersed electrostatically charged material.

Description

The present invention relates to a device for localized distribution of

  electrifiable materials, a printing installation equipped with at least one of these

devices enabling continuous sur-

  printing of patterns of non-fixed electrifiable materials,

  and the decorated supports obtained on this installation.

  The devices for distributing electrifiable materials on any support previously covered with an adhesive layer intended to receive the

said materials are well known. These devices include

  in essence, pose a vibrating screen, the lower grid of which, connected to a high-voltage generator, creates an electrostatic field by which the electrifiable materials, whether cut fibers or flocs,

  or any other particulate matter are directed per-

  pendulum to the support to decorate and come im-

plant on the areas of said surface beforehand

covered with adhesive.

Some of these devices are fitted with

fixed rings allowing them to be divided into different

compartments containing for example, in the case of the flo-

  cage, cut fibers of different colors, which allows, in a single operation, effects

flocked in different colors.

  It is always necessary, in order to obtain a perfect relief effect, to rid the support of excess electrifiable materials which have not settled in the area or areas of the covered support

  adhesive. In installations using the devices

  current cleaning, this cleaning operation involves,

notably due to the relatively large quantities

  so many materials not retained by the adhesive layer,

energetic mechanical means of suction and beating

  floor. You can also use a cleaning system

  electrostatic. Indeed, when the electric matter

sand, which is polarized when passing through the screen grate, comes into contact with the plate connected to ground, it changes polarity. Instead of being pushed back

  by the screen grate, it is on the contrary

  drawn and theoretically rises in the sieve. In practice, electrostatic deflocation often proves to be insufficient. Part of the electrifiable material adheres to the support and cleaning must be completed with a vacuum cleaner. These cleaning operations must therefore, in order not to harm the good appearance of the coated support, be carried out once the electrifiable materials implanted on the adhesive are securely fixed to the latter. Current materials application processes

electrifiable require the following steps; app

electrostatic cation of said materials on the adhesive-coated support, fixing, most often thermally, of said materials on the support and cleaning by electrifying or by two combined processes, of electrifiable materials

not fixed.

  The current process of applying electrifiable materials has the disadvantage of dispersion

In fact, electrifiable materials, generally available

  tributed by a screen with rectangular grid, present

due to the electrostatic phenomenon, a movement of

  1st and back between the polarized grid and the item to be decorated which is fixed on a connected metal plate

  to ground. In the center of the grid, the electro

trisables have a vertical back and forth movement.

On the edges of the grid, they tend to go outwards under the influence of the lines of force

  of the magnetic field. Arriving outside, these ma-

  electrified thirds are attracted to any mete

surrounding metal, resulting in an annoying dispersion for

  the screen printing operations which are carried out near

  moth. So far it is impossible, except to develop a complex and bulky installation

  to carry out on a single installation the application

  cation of electrifiable materials on a support and

the colored impression of the parts of the support thus coated

you. You must first apply the materials, fix the pattern obtained, then, after cleaning the support, transport everything on a printing machine. The purpose of the present invention is to remedy this drawback, and to make it possible to carry out

  continuously, and on the same installation, the applica-

  tion of electrifiable materials and the overprinting of the relief pattern thus obtained, without it being necessary

  to proceed to the intermediate fixing step of the ma-

  electrified thirds. The present invention makes it possible to-

  almost completely avoid the dispersion of electrifiable materials and allows the incorporation of a flocking cell in a mechanical screen printing system without disturbing its functions and avoiding clogging of

  printing frames with electrifiable materials in dispersioc.

  The invention firstly relates to a provision

  local distribution of electrified materials

  wheat of the type-constituted by a vibrating screen, provided with partitions, the lower grid of which is connected to

  a high voltage generator and whose originality

  sists in that the said partitions are constituted

by a series of independent removable cylindrical elements

  dants, in non-conductive material, with parallel axes,

of uniform or variable diameter, arranged perpendicular-

lairement to the screen grid, and whose maintenance in desired position is ensured by simple contact of said cylindrical elements along leuisgénératrices, the outer row of said elements being for its part

  also in contact along the generators of the

with the internal walls of the sieve.

  In addition, two devices are associated with this device.

  additional removable pads usable successive-

  to ensure the proper functioning of the device.

  The first of these covers, connected to a hopper for supplying electrifiable materials, is designed to leave uncovered a part of the cylindrical elements according to a surface corresponding essentially to that of the pattern which it is desired to apply, the other cylindrical elements being covered, while the second cache,

  complementary to the first and connected to an as-

  piration, is planned to cover the part of the elements

cylindrical previously discovered.

There is thus a very flexible application device making it possible to modulate at will the quantity of electrifiable materials which it is desired to apply to

a support.

  Indeed, first, the introduction

  electrifiable materials will be limited to only those

  cylindrical elements corresponding to the surface that

wants to put on. This operation is carried out before the

purpose of the electrifiable materials application process

  and will only need to be renewed when the reservation

see constituted by tubes filled with electrical materials

  sands will be emptied in the succession of application operations. In a second step, the reservoir constituted by the tubes filled with electrifiable materials will be protected against the action of the suction device by the second cover, leaving only the elements exposed.

cylindrical masked by the first cover. A ju-

dicious of cylindrical elements of different diameters is enough to adapt them to the opening made in the first cover, this corresponding opening

substantially on the ground that one wishes to obtain.

The advantages of this device are numerous.

  First of all, it allows for significant savings.

  a lot of electrifiable materials compared to the available

existing sitives; when switching on the device

  positive almost all electrifiable materials

will be installed on the part of the prior support-

  covered, depending on the pattern chosen, with a layer of adhesive. The simple replacement of this first cover by the second complementary cover, connected to the device

  then ensure the elimination of the

  ble quantity of electrifiable materials which would not

  not implanted on the adhesive, the part of the support

  jà coated said materials being preserved from ac-

  mechanical suction by the second cover.

In addition, the suction, performed simultaneously-

  the electrostatic application of electrical materials

  trisable avoids the dispersion effect described above. It is therefore no longer essential to carry out the fixing operation before the cleaning operation and this important fact makes it possible, according to another object of the invention, to incorporate at least one of these devices

  on a printing installation, instead for example-

  full of at least one of the item placement stations.

  We can thus continuously perform the application of

  electrifiable materials and their overprinting and effecting

  then kill the simultaneous fixation of electrical materials

sands and overprinted pattern.

  According to a particular embodiment of

invention and in order to improve the speed of operations

tions, we have side by side a distribution device

  localized fuel with a second cover covering the surface corresponding to the pattern and connected to a first

  suction device, and a second similar device

  laire, but without distribution, and connected to a second

suction device covering the corresponding surface

laying on the ground.

The invention also relates to the patterns in

  overprinted relief obtained by implementing the

  printing plant comprising the distribution device

  localized tribution of electrifiable materials according to the invention.

The present invention will also be better understood.

  their and its advantages will emerge clearly from the description

  tion which follows with reference to the appended schematic drawing in which:

Figure 1 is a very schematic perspective view

  tick partially torn from the localized dispensing device according to the invention, Figure 2 is a perspective view of the device of Figure 1, covered with the first cover, Figure 3 is a view similar to Figure 2, in which the first cover has was replaced by the second

additional cover. -

  In the figures, - 2 represents the vibrating screen, 3 the grid, 4 the cylindrical elements, 5 the first

cover connected to the feed hopper 6, and 7 the two

tenth cover connected to the extractor hood 8. -

  The device according to the invention consists of a vibrating screen 2, the lower grid 3 of which is connected

to a high voltage generator (not shown). Inside

inside the sieve 2 and resting on the grid 3, are

  laid cylindrical elements 4, removable, independent

  dants, with parallel axes. These cylindrical elements are made of a non-conductive material such that, for example

  example, polyvinyl chloride. Elements 4 represented

seen in the figures all have the same diameter, but they can of course have different diameters

  one another. Keeping them in the desired position

  This is ensured by contact with neighboring elements along their generators. The elements 4 forming the outer row of the assembly are also in contact with the inner walls of the screen 2 according to

their generators.

  Figure 2 shows the device of Figure i when it is used for loading electrifiable materials.

As can be seen in the figure, on the part above

of the screen 2, opposite the grid 3 is

placed a cover 5 connected to the feed hopper 6.

The opening of the hopper 6 adapts to a cutout 9

formed in the cover 5. This cut made essentially

  tially according to the outline of the pattern that one wishes to represent

  covering with electrifiable material leaves exposed a corresponding number of cylindrical elements 4 and masks all the others; the diameters of the different elements

cylinders left uncovered are chosen in such a way

Less that the cutout 9 of the cover 5 leaves uncovered only entire sections of cylindrical elements. During the introduction of electrifiable materials into the hopper 6, only the cylindrical elements 4 left uncovered and which essentially correspond

  on the grounds that we wish to reproduce.

The step of simultaneous application and cleaning is shown in Figure 3; the cover 5 has been replaced by a cover 7 which is complementary thereto, that is to say which corresponds exactly to the cutout 9 of said cover 5;

the cover 7 is then placed on the part of the cy-

  lindriques left uncovered, during the previous steps

  teeth, and the assembly is connected to the suction hood 8.

  The support 10 was previously, as it is known per se, coated with a layer of adhesive according to the

  same. pattern and placed in a conventional manner, and not shown

under the localized distribution system, compared

port with cutout 9 of cover 5.

The screen 3 of the screen 2 is then energized

in a conventional way and we carry out the projection of the ma-

electrifiable thirds contained in the cylinder elements

  cracks corresponding to the cutout 9 of the cover 5, on the part of the support 10 coated with adhesive according to the drawing

of the pattern.

  It is clear from the above that almost all of the electrifiable materials supplied in the said cylindrical elements will be installed in the glued part of said support 10, which corresponds to a significant saving in electrifiable materials

247 241 7

  that a significant reduction in pollution of the

  environment. Under the action of the suction device 8, the part of the support where the electrifiable materials have been installed will be protected by the cover 7 against the suction action which will therefore only be exerted on the

unprotected parts of the support and will eliminate the

electrizable thirds not fixed.

  We can easily see that it is possible

to perform on the pattern thus obtained on which

  that all electrifiable materials will have

was installed in the part of the support coated with

sif and will therefore be kept there enough to be able

  withstand the action of pressure, a co-overprint

lorée.

  The localized distribution system for ma-

  electrified thirds described above therefore allows, and

this constitutes another object of the invention, of realizing

be on the same installation, and continuously, the app

  cation, in an embossed pattern, of electrical materials

  sands and overprinting them without the need

  to use an intermediate fixing step.

It suffices to replace at least one of the stations of a screen printing machine with

a device according to the invention.

  Thus on a conventional screen printing machine (not shown) comprising six

placement stations for articles to be printed and six heads

  your printing stations, the three stations preceding the printing heads will be equipped as follows: the first station is constituted by a scraping head making it possible to apply the adhesive on the support according to the pattern which it is desired to obtain, the next station is constituted by a localized distribution device according to the invention, previously filled with electrifiable materials according to the

  pattern to be made using the first cover, then mu-

nor the second cover and connected to a vacuum device

  tion, and the next station of the same device but without distribution of electrifiable materials and connected to the

extractor hood, the print heads allowing

  following to directly overprint the desired drawing to the relief pattern. The overprinted assembly then passes through a conventional fixing device, by thermal means for example, in which the fixing of the electrifiable materials to the adhesive will be carried out simultaneously.

and that of the overprinted drawing.

  The invention also relates to the patterns in

  overprinted relief obtained on the above installation.

  As is obvious, and as is clear from the foregoing, the present invention is not limited to the sole embodiments described above by way of nonlimiting examples, it embraces, on the contrary, all of the embodiments comprising equivalent means, whatever the structure of the printing installation and the number of heads

printing.

Claims (5)

- CLAIMS -   1 - Device for localized distribution of ma- electrizable faces of the type constituted by a sieve   brant, provided with partitions and whose lower grid   is connected to a high voltage generator,   characterized in that the said partitions are formed by a series of removable cylindrical elements independent, in non-conductive material, of parallel axes   Islands, of uniform or variable diameter, arranged per- perpendicular to the screen of the sieve and whose hand-   your position is assured by simple contact said cylindrical elements along their genera-   trices, the outer row of said elements being   for its part also in contact, along the genera-   elements with the internal walls of the sieve,   and to this device are associated two removable covers   additional wards that can be used successively for   check that the device is working properly, the first cache   connected to an electrified material feed hopper   leaving uncovered a whole number of cylindrical elements corresponding essentially to the surface of the pattern that one wishes to apply and the second cover, connected to a suction hood covering exactly the cylindrical elements left uncovered during the previous step.   2 - Installation for printing relief patterns made from electrifiable materials, characterized in that at least one of the placement stations of the   item to be printed in a serial printing machine spelling is replaced by a distribution device   located according to claim 1.   3 - Printing installation as sold   cation 2, characterized in that the three positioning stations cement preceding the print heads are constituted by a scraping station of the adhesive according to the drawing of the   pattern, by a localized distribution device, previously lably charged with electrifiable materials according to the 11. sin using the first cover, then fitted with the second   cover connected to an extractor hood, followed by a provision similar situation but without distribution of electro trisables connected to an extractor hood, and that a positive fixing is provided at the exit of the installation.   4 - Application of the installation according to the   vendications 1 and 2 to the production of overlays on patterns of non-fixed electrifiable materials.   5 - Patterns overprinted in relief obtained by implementing the installation according to any one of claims 2 to 4.