U.S. patent number 3,649,810 [Application Number 05/062,115] was granted by the patent office on 1972-03-14 for hot screen printing machine.
This patent grant is currently assigned to Fuji Photo Film Co., Ltd.. Invention is credited to Tsuneo Komura, Asaji Kondo, Sigeru Tezuka, Masayoshi Tsuboi.
United States Patent |
3,649,810 |
Tsuboi , et al. |
March 14, 1972 |
HOT SCREEN PRINTING MACHINE
Abstract
A practical and useful hot screen printing machine having at
least one rotatable cylindrical printing drum comprising a flexible
plane heater on the outer surface thereof and an electrical
insulating layer surrounding the plane heater.
Inventors: |
Tsuboi; Masayoshi (Asaka,
JA), Komura; Tsuneo (Asaka, JA), Tezuka;
Sigeru (Asaka, JA), Kondo; Asaji (Asaka,
JA) |
Assignee: |
Fuji Photo Film Co., Ltd.
(Kanagawa, JA)
|
Family
ID: |
13227880 |
Appl.
No.: |
05/062,115 |
Filed: |
August 7, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Aug 11, 1969 [JA] |
|
|
44/63389 |
|
Current U.S.
Class: |
219/216; 219/469;
100/327; 100/334; 100/330 |
Current CPC
Class: |
B41L
13/06 (20130101); B41M 1/12 (20130101) |
Current International
Class: |
B41M
1/12 (20060101); B41L 13/04 (20060101); B41L
13/06 (20060101); H05b 001/00 () |
Field of
Search: |
;219/216,244,388,469-471,338,528,529,538,544,549,552 ;29/130,132
;100/93RP ;338/212,223-225 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Albritton; C. L.
Claims
We claim:
1. A hot screen printing machine comprising at least one rotatable
cylindrical drum;
a flexible sheet of electrically conductive material wrapped around
the drum and capable of generating heat comprising a heat resisting
polymer film containing a material selected from the group
consisting of carbon black, grafted carbon, aluminum powder, silver
powder, and copper powder;
an electrically insulating layer on the outside surface of the drum
and above the sheet of electrically conductive material and formed
of a material selected from the group consisting of polyethylene
terephthalate film, cellulose triacetate film, felt and sponge,
and
means for supplying electricity to the heat generating flexible
sheet including a pair of electrodes positioned parallel to the
drum and extending across the surface of the flexible sheet beneath
the insulating layer.
2. A hot screen printing machine as in claim 1, where the means for
supplying electricity further includes lead wires and brush type
current collector means connected to the electrodes and positioned
at one end of the drum radially inward of the electrodes.
3. A hot screen printing machine as in claim 2, where the thickness
of the flexible sheet is between 20 microns and 2 mm.
4. A hot screen printing machine as in claim 3, where the
temperature of the flexible sheet will remain within 3.degree. C.
at steady state and the electrodes will be positioned approximately
25 cm. apart on the flexible sheet.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a hot screen printing machine.
More particularly, the present invention is concerned with a hot
screen printing machine comprising a flexible plane heater on the
printing drum.
The heating of the printing drum in presently known hot screen
printing processes has been generally conducted indirectly by means
of an electric heater such as nicrome wire, infrared rays, hot air
or steam.
In a series of studies of the hot screen printing process, we have
found that an excellent print can be easily obtained in the
combination of the hitherto known screen printing machine having a
printing drum, for example, single or double drum type printer,
with a plane heater as the heating source.
SUMMARY OF THE INVENTION
That is to say, the hot screen printing machine of the present
invention comprises at least one rotatable cylindrical printing
drum provided with an electric insulating layer surrounding a plane
heater having electrodes on the outer surface of the printing drum
thereof.
An object of the present invention is to provide an improvement in
a screen printing machine. Another object of the present invention
is to provide a practical and useful hot screen printing machine as
mentioned hereinafter and illustrated in the drawings.
Another object of the present invention is to propose a practical
screen printing process suitable to obtain printed matter with a
very clear image in an easy operation by using the improved hot
screen printing machine.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view, partly in section, of a portion of
the printing drum of the hot screen printing machine of the present
invention; and
FIG. 2 is another perspective view of a portion of the hot screen
printing machine of the present invention.
FIGS. 3 and 4 are respectively temperature versus voltage and time
graphs for the heater of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates a printing drum 1 for use in the single drum
type screen printing machine of the present invention. The drum 1
comprises a plane heater 3 on the outer surface thereof, and an
insulating layer 2 disposed inwardly of the heater 3.
As shown in FIG. 2, electrodes 4a and 4b, substantially parallel to
the center shaft 6, are disposed on the surface of the plane heater
3. Lead wires 5a and 5b connected to the electrodes 4a and 4b
respectively, are contacted with circular electrodes 8 and 9,
respectively, which are positioned at the side of the printing drum
1 and separated by an annular insulating layer 7. The circular
electrodes 8 and 9 are connected with a source of electricity (not
shown) by current collectors 10 and 11.
In this case, the prevention of an electric shock may be easily
effected by providing an insulating layer 12 on the surface of the
plane heater 3.
Alternatively, the electrodes 4a and 4b may be positioned along one
end of the circumference of the printing drum 1.
Although the drawing illustrates a single drum type printing
machine, a double drum type may be utilized in accordance with the
teachings of the present invention.
The other parts in the hot screen printing machine according to the
present invention are similar to the hitherto known screen printing
machine; namely, a hand-operated lever or an automatic rotating
apparatus (not shown) is provided for rotating the drum shaft 6,
and a pressure roller 13 is in engagement with the printing drum
3.
The plane heater 3 may be formed, for example, of a molded plastic
material of any suitable type. As illustrative examples, a
film-forming polymer may be mixed with an electrically conductive
material, or such a polymer may be applied uniformly with an
electrically conductive material onto a suitable base, such as
glass cloth, the polymer preferably being of the heat-resistant
type. Also, it may be possible to use a cloth made up of an
electrically conductive fiber.
The electrically conductive material for the plane heater 3 may be
selected from the group consisting of carbon black or grafted
carbon, aluminum powder, silver powder and copper power, used
singularly or in combination. A plane heater having a thickness of
20 microns to 2 mm. is preferable so that it is sufficiently
flexible to be easily wound around the printing drum 1.
The insulating layer 2, for example, may be selected from the
groups consisting of polyethylene terephthalate film, cellulose
triacetate film, felt or sponge.
The temperature of the ink layer used in the hot screen printing
machine of the present invention should be below the limit of heat
resistance temperature of the screen stencil and it is usually at a
temperature less than about 90.degree. C. Since the surface
temperature of the plane heater 3 does not have to be more than
20.degree. C. higher than the temperature of the ink layer, the
heater 3 may generally be maintained at a temperature less than
about 110.degree. C.
The plane heater 3 may be charged with either a direct current or
an alternating current, but usually an alternating current is
preferable. A pair or more of the electrodes 4a and 4b parallel to
the shaft 6 of said printing drum 1, or a pair or more of the
electrodes along the circumference of the drum, may be equipped and
charged with a sufficient voltage such that said plane heater 3 is
maintained at the desired temperature.
The relation of the charged voltage with the temperature in case
where the plane heater 3, having 170 microns thickness, prepared by
adding 20 percent by weight of carbon black to cellulose
triacetate, is charged through electrodes (25 cm. distance) is
illustrated in FIG. 3. The relation between the temperature and the
time in case of charging the electrodes with 80 v. is illustrated
in FIG. 4. As is understood from FIGS. 3 and 4, it requires only
about 90 seconds for reaching 80 percent of the thermal variation
from room temperature 26.degree. to 60.degree. C., namely,
53.2.degree. C., and the thermal fluctuation on the surface of said
plane heater 3 is within 3.degree. C.
The application of the plane heater 3 to the hot screen printing
machine is markedly advantageous in view of the simplicity of the
attachment of the heater to the printing drum, owing to its
flexibility in addition to the possibility of rapid elevation of
temperature with maintaining a uniform thermal distribution.
The printing machine of the present invention makes it possible to
use an ink which is at a solid state at ordinary temperatures, due
to the possibility of printing at a temperature higher than an
ordinary temperature, thereby conducting the printing operation
with less staining of hands, etc., during the operation.
In the practice of screen printing by means of the hot screen
printing machine of the present invention, an ink for screen
printing is directly applied from a tube or a can to the insulating
film 12 overlying the plane heater, and the printing operation can
be run at a constant temperature elevated from ordinary
temperatures.
With respect to the supply of the ink, a method of using an ink
sheet is very superior to the above. The term "ink sheet" is used
herein is intended to cover one prepared by applying an ink on a
sheet of a support inactive to the ink or a support that is not
permeated by the ink at a temperature range imparting the fluidity.
If an ink, which is solid at ordinary temperatures, but fluid only
when heated to a temperature higher than an ordinary temperature,
is used for the screen printing machine of the present invention,
there is no fear of staining hands and clothes with the ink, other
than when actually printing.
Consequently, if a solid ink having a fluidity desirable for
printing at a temperature ranging from 50.degree. to 70.degree. C.
is employed in the hot screen printing machine of the present
invention, the solid ink can be easily heated to a temperature
imparting the desirable fluidity within 1 to 3 minutes, and thereby
the screen printing can be effectively conducted in a conventional
screen printing stencil.
The following specific examples are intended to show the nature of
the invention without limiting it to the examples themselves.
EXAMPLE 1
A printing drum of a single drum type rotary mimeographic copying
machine (for example, Sekisei Rotary Copying Machine) was remodeled
as follows.
A polyester film having 15 microns thickness was wound around an
aluminum printing drum having 4.5 cm. in radius to insulate the
drum, and a cellulose triacetate film (170 microns thickness)
containing 20 percent by weight of carbon black content as the
plane heater was layed on the polyester film layer, and further a
polyester film having 100 microns thickness as an insulator was
wound around the heater.
Aluminum foil having 0.5 cm. in width was adhered in the direction
parallel to a shaft of the printing drum to both ends (25 cm.
distance) of the plane heater by using an electrically conductive
paste to make electrodes respectively, and lead wires and brush
type current collectors were connected to the electrodes.
When the hot screen printing machine was charged with 80 v. of
alternating current, the surface temperature became 54.5.degree. C.
within 2 minutes.
An ink sheet, which was prepared by applying to a cellophane sheet
(30 .times. 40cm.) so as to leave 4 cm. of the circumference free,
15 g. of ink made up mainly of 90 parts of paraffin, 3 parts of
cellulose flock and 7 parts of carbon black, and was at a solid
state at an ordinary temperature under 60.degree. C., was set on
the printing drum of the hot screen printing machine and, after
laying a mimeographic stencil paper cut with a typewriter on the
ink sheet, the printing was started while beginning to impart
fluidity to the ink.
In this process, 100 sheets of clearly printed matter were
produced.
EXAMPLE 2
The plane heater used was prepared by applying an 80 percent
concentration dispersion of grafted carbon (produced by Nippon Gas
Chemical Industries, Ltd.) containing 50 percent by weight of
carbon black onto a glass cloth and drying it. The hot screen
printing machine was made up as in example 1.
In this case, since the glass cloth served as an insulating layer
for the aluminum drum, the polystyrene film having 15 microns in
thickness was not required.
When the machine was charged with 70 v. of alternating current
through the electrodes (25 cm. distance), the surface temperature
became 70.degree. C. within 25 minutes.
As the ink supplying source, there was used an ink sheet prepared
by applying a colorless ink containing a dye base to a support, and
then the hot screen printing was conducted using clay paper,
applied with an acid clay, as the printing paper.
The term "dye base" used herein is intended to cover a leuco
pigment, a lactone derivative of pigment, a lactam derivative of
pigment and the like.
The colorless ink was prepared by mixing 1.5 g. of crystal violet
lactone, 15 g. of diphenyl tetrachloride, 20 g. of triphenyl
chlorinate and 30 g. of paraffin having a melting point of
62.degree. C. under heating.
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