Note: Descriptions are shown in the official language in which they were submitted.
-
18
The present invention relates to a printing ink trans-
fer process and apparatus in which printed information in the
form of printing ink is transferred to a non-porous substrate,
for example, a synthetic resin substrate.
In the past color images on non-porous substrates have
been produced by photographic processes, printing on cellophane
and attaching the printed cellophane to the substrate by means
of an adhesive, a transfer process involving the use of a release
agent between a carrier and the information to be attached to
the substrate.
The photographic method mentioned is expensive and pro-
duces an image which while satisfactory initially, quickly fades
to an unacceptable extent.
Attaching a printed cellophane sheet to a non-porous
substrate by adhesive results in an entirely unsatisfactory pro-
- duct as a result of the poor quality of print obtained by print-
ing on cellophane, delamination which occurs even at room temp-
eratures which results in the cellophane peeling away from the
substrate, lack of definition of the printed subject matter, un-
due expense and low resistance to ambient heat.
The conventional transfer arrangement using a release
agent is unsatisfactory for large products or printed informa- ~`
tion of great complexity and is relatively expensive.
It is an obJect of the present invention to provide a
process and apparatus capable of transferring complex high
definition multi-color printed sub~ect matter from the printed
paper upon which it was printed onto a non-porous substrate,
for example, a synthetlc resin board, without apparent deteriora-
tion in quality of the printed image. It is a further ob~ect to
provide such a process and apparatus capable of producing a
-2-
': ' ., - .; , ,. ' '` , , ' ~, ;' , ';'' ,'` ` `, ~, :
~0~4~L8
a product substantially more resistant to fading than photo-
graphic processes and more resistant to ambient temperature and
delamination while also having a significant economic advantage
over the prior art processesO
According to the present invention there is provided
a process for transferring printed information consisting of
printing ink, from a printed surface of a printed paper carrier
to a substrate having at least one smooth substantially non-
porous surface, comprising the steps of applying transparent
adhesive to the printed surface to form a coating of adhesive
thereon; applying transparent adhesive to the smooth surface to
form a coating of adhesive thereon; when said adhesive is dry,
simultaneously applying a solvent for the adhesive to the coat-
ed surfaces of the printed paper and the substrate; when the
solvent has activated the exposed surfaces of the adhesive coat-
ings and before the entire coating has been affected by the
solvent, pressing the activated surfaces together to unite the
adhesive coatings and squeeze any excess solvent from between
the coatings; and when the united adhesive is dry, applying a
solvent for the paper to the paper and removing the dissolved
paper thereby leaving the printed information attached to the
substrate by means of said adhesive.
In a preferred form of the process the above steps
are repeated in sequence, with the exception of the step for
applying adhesive to the substrate which is omitted, to add
further layers of printed information superimposed in registra-
tion with the printed information attached to said substrate in
said steps. Subsequently a backing layer may be added to pro-
tect the adhesive and printing ink attached to the substrate.
The invention also provides an apparatus for trans-
--3--
:,
ferring printed information consisting of printing ink, from a
printed surface, coated with adhesive of a printed paper carrier
to an adhesive coated smooth substantially non-porous surface of
a substrate comprising, a first solvent applicator for simul-
taneously applying a solvent to adhesive coated surfaces of the
printed paper and the substrate, a pressure applicator to press
the solvent activated surfaces together to unite the adhesive :
coatings and squeeze any excess solvent from between the coat-
ings, a second solvent applicator to apply a paper solvent to
the paper and means to remove the dissolved paper to leave the
printed information attached to the substrate by means of said
adhesive.
An apparatus and process according to the invention
will now be described, by way of example, with reference to the
15 accompanying drawings:
Figure 1 is a diagrammatic representation of apparatus .
in accordance with the invention;
Figure 2 is a diagrammatic representation of a spray
gun spraying adhesive onto printed paper~
Figure 3 is a diagrammatic representation of a spray
gun spraying adhesive onto a substrate; and .
Figure 4 is a fragmentary cross-section of a product
of the apparatus and process of the present inventionO
With reference to Figure 1 a roller conveyor is
diagrammatically represented by freely rotatable rollers 1 with
all of the rollers lying in a single horizontal planeO In a
first section 2, rollers 1 are arranged to support a substrate
3, coated on its upper surface 4 with an even continuous coat-
ing of transparent adhesive, for passage in the direction of
arrow 5~ between horizontal pressure rollers 6 and 7O Roller 6
--4--
3~1~
has a rigid core with an exterior surface layer 8 of a resilient
material such as a synthetic rubber (eOg., "Neoprene") and
roller 7 is ~- rigid cylindrical steel rollerO Rollers 6 and 7
are arranged to press a printed paper 9 (e.g., a poster) which
~onsists of a paper backing carrying, on its face 10, printed
i~formation, comprising printing ink~ over which is an even con-
tinuous coating of a transparent adhesive.
A solvent carrying tray 11 with output spray nozzle 12
is disposed ad~acent the input nip of rollers 6 and 7 to spray
the coated upper surface 4 and coated face 10 immediately befo~e
and as substrate 3 with superimposed paper 9 are fed between
pressure rollers 6 and 7O The pressure applied by pressure
rollers 6 and 7 is sufficient to squeeze excess solvent from
between the substrate 3 and the printed paper 9 to unite the
coatings. The solvent carried by tray 11 and sprayed by nozzle
12 activates the exposed surface of the adhesive which coats
surface 4 and ~ace 10 and the positioning of nozzle 12 in rela-
tion to rollers 6 and 7 is such that as the superimposed substrate
3 and printed paper 9 are fed between pressure rollers 6 and 7 the
solv~nt sprayed by nozzle 12 has time only to effect khe surface
of the adhesive coatings which are to be pressed into contact by
rollers 6 and 7.
It will be appreciated that rollers 6 and 7 may be
manually turned or turned by a motor (not shown).
With respect to the coating of the substrate 3 and
printed paper 9 with a layer of adhesive as described with
reference to section 2 of Figure 1, attention is drawn to Figure
2 and Figure 3 which respectively show spray guns 13 and 14
(of any well-known type) which may be used to spray continuous
even coatlngs of transparent adhesive on surface 4 and face 10.
~B *Regfstered Trade Mark.
.
.. ., . . .... .. :... . .. - . .. .. .. . .
.. . : . , ,.. - , ~: .. . .. .,. . . . ,- . . .. ... . .
., . , . .. : :. . . . .. ....
., . , . , , j, , ., .... , " .
.. ~ .~ . : . . , : . . . ,: .
~ 334~3
It will be appreciated that this may be done manually or by
automatic spraying apparatus in a manner well-known in the art
of spraying of coatings onto surfaces~
Following passage of the substrate 3 and superimposed
printed paper 9 between rollers 6 and 7 and now ~oined adhesive
coatings are allowed to dry to form a laminate consisting in
order of substrate 3, a layer of adhesive, a layer of printing
ink and a layer of paper 9~ Following drying the laminate is
passed to the second section 15 of the apparatusO Section 15,
located on a continuation of the roller conveyor, is a paper
stripping section in which the paper of the printed paper 9 is
removed, by use of a solvent, a scrubber and a rinsing agent,
to leave the laminate formed in section 2 with the paper, on
which the printed matter was printed, removed. The laminate
produced in section 2 is passed through section 15 in the direc-
tion of arrow 16 by either manual or mechanical means. During
the passage of this laminate through section 15 it is first
sùb~ected to a spray of solvent issued by a solvent tank and
nozzle 17, the solvent being of a formulation which will soften
and dissolve the paper of the printed paper 9 without significant
dissolution or disturbance of the printed information printed
thereonO The laminate is then transported in the direction of
arrow 16, to a scrubber roller 18. The rate of transport is
such as to permit sufficient time for the solvent to soften and
substantially dissolve the paper backing before reaching the
bristles 19 of the scrubber roller 18~ The bristlès remove the
dissolved and partially dissolved paper, leaving the printed
information, in the form of printing ink, intact on the surface
of the adhesive. The scrubber roller 18 rotates in the direc-
tion of arrow 20 at a peripheral speed substantially exceeding
--6--
.. ~1 . .
.; .... . , ,, , ,., , , , ,~, ,, . :
' , -. ,.: ' ' - ', : .: ' ' ' . .. . ,.'.. ,.'' '.. :. ' .
: - :'' - ' ' ' . , :: . . :' ,' ' ',' ''
-. .'. . ,.' , . ' . ., . ~ :,. ' ' ': :
.. ., ~ , ,. , . :
~ 4~8
the rate of transport of the laminate through section 15. The
bristles 19 of sorubber roller 18 may be constructed of any
suitable material as will be readily apparent to a man skilled
in the art and are chosen to have a stiffness sufficient to re-
move the dissolved or partially dissolved paper without mate-
rially disturblng or destroying the printed information which
is to remain on the laminate. Preferred bristles are constructed
of a Nylon ~Registered Trade Mark) with the outer ends of the
~ristles rounded to avoid undue abrasiveness.
Following scrubbing with the scrubber roller 18 the
laminate passes under a rinsing head 21 which is connected by
way of valve 22 to a supply of water (not shown). Water from
the rinsing head 21 washes the loosened particles of dissolved
and partially dissolved paper from the laminate leaving the
layers of the substrate 3, adhesive and printed information 10
intact.
Following the dissolving, scrubbing and rinsing
actions which occur in section 15 the laminate is allowed to
dry before recycling through sections 2 and 15 to build up
additional layers of adhesive and printed information used to
increase the density of color of printed information by the
superimposition of a plurality of layers of printing ink in
registration. For laminates which are to be illuminated by
back~lighting, two or three suoh superimposed layers of printed
information are usually required, while in the case of an opaque
substrate 3, which is to be illuminated from the viewing side
only, a single layer of printed information may well suffice.
During each recycling step an additional and identi-
cal printed paper 9 is utilized. After desired recycling, the
laminate is passed to the third section 23 of the apparatus for
-7-
. ~ :
.
~Z334~8
the application of a backing layer 24. The backing layer 24,
which may be opaque, translucent or transparent, is coated on
surface 25 with a continuous coating of transparent adhesive
compatible with the adhesive utilized in the lamination taking
5 place in sections 2 and 15 and activatable by a solvent which
will also activate the adhesive utilized in the manufacture of
the laminate in sections 2 and 150
The laminate 26 produced in sections 2 and 15 is
passed through section 23 in the direction of arrow 27 between
pressure rollers 28 and 29. These may be rotated manually or
by a motor (not shown) in the same manner as rollers 6 and 70
Roller 28 is a resiliently covered roller similar to roller 6. The backing
sheet 24 iS superimposed over the adhesive and printing ink covered surface of
substrate 3 with adhesive 25 sandwiched~therebetween. A solvent tray 30 and
15 nozzle 31 is disposed in section 23 to spray solvent into the entry nip
of rollers 28 and 29 immediately prior to the passage of the
superimposed backing layer 24 and laminate 26 between these
rollers. The rollers squeeze excess solvent from between the
backing layer 24 and laminate 26 and press the backing layer 24 - ;
20 into lamination with the laminate 26. The backing layer 24
provides a protective layer for the layers of adhesive and print-
ing ink formed on the substrate 3~ Following passage through
rollers 28 and 29, the adhesive dissolved by the solvent issuing
from nozzle 31 is allowed to harden to produce a unitary struc-
25 ture which may then be utilized in any desired manner.
In a process using the apparatus shown in Figure 1 inwhich three layers of printing ink are attached to substrate 3
an arrangement will be produced as shown in Figure 4. Here sub-
strate 3 has a coating of adhesive 32 which is a combination of
the adhesive applied to surface 4 o~ substrate 3 prior to its
--8--
~, .j , .
:.~ ' , . - : ~ , ,,
.
. ..
~ 8~4~3
first passage through sections 2 and 15 and the adhesive applied
to khe first printed paper 9 used in the production of the re-
sulting laminateO To this adhesive layer 32 is attached the
printed information from the first used printed paper 9. Super-
imposed upon layers 32 and 33 are layers of adhesive 34 and 35
which alternate with additional layers of printed information
36 and 37 which are superimposed in registration over the print-
ed information layer 33 to have the appearance, when looking in
the direction of arrow 38, of a single representation of the
printed information. Finally, the backing layer 24 with its
layer of adhesive 39 follows to produce the completed laminate,
in this instance, having three superimposed layers of printing
ink.
The process of the present invention may be carried
out in the apparatus described with reference to Figure l. How-
ever, it wilI be appreciated that the process, hereinafter
particularly described, does not necessarily involve the use of
apparatus such as that described with reference to Figure l and . .
that this process exhibits the inventive concept of the present ~ ~ .
invention even when such apparatus as that described with refer-
ence to Figure l is not usedO --
The process to be described will be described with
reference to the use of a substrate which is a transparent
acrylic sheet upon which the layers of printing ink and adhesive .
are deposited before a backing layer of translucent white
acrylic sheet is attached to the exposed printing ink surface of .
the intermediate laminateO
An even continuous coating of a vinyl glue (polyvinyl
acetate copolymer) is formed on one surface of the substrate and .
allowed to dry. A similar even continuous coating of vinyl glue
_9_
, ~
:. ' ' ' . ' ' , ', .. '' .: :'' , ' , ~' ' " ' . ' :
~ 39L18
is formed on the face of a printed paper which carries the
printed information, in the form of printing ink, the transfer ~ -
of which is desired This coating is also allowed to dry.
At a temperature excess of 15C. solvent in the form
of approximately equal parts of benzene and toluene in admix-
ture is applied to the adhesive coated surfaces of both the
printed paper and the substrateO The solvent activated sur-
faces of the coatings of the printed paper and substrate are
then brought into contact with one another and pressure is
applied across the thickness of the paper and substrate to
squeeze excess solvent from between the paper and the substrate
and to produce a uniform bond between the surfaces of the ad-
hesive coatings to produce a uniform integral layer of substan-
tially void free adhesive between the substrate and the printing
ink surface of the paperO The period of time between the appli-
cation of the solvent and the application of pressure to produce
the integral uniform layer of adhesive is chosen to be sufficient
to ensure adequate wetting of the surface of both coatings while
being insufficient to permit the dissolution of the entire thick- .
ness of the coatings concernedO This period which will differ
with the thickness of coating, particular adhesive composition
used and temperature, may be easily ascertained by simple -
experiment~ In a manually operated process a period of 1 to 2
seconds has been found appropriate and, further, has not been
found to be particularly critical
The adhesive layer joining the printed paper and sub-
strate is then allowed to dry to form a laminate, the layers of
which consist in order of the substrate, adhesive printing ink :
and paper.
Solvent for the paper is then applied to the paper
-10-
.. . ....... .. . .
' ~ , '. ' ' ~ .
.. :: ~ ~ , . ,
, ~ ,
;
~ 334~
layer by either brushing or sprayingO This solvent which is
chosen to dissolve the paper backing without materially effect-
ing the layer of printing ink beneath or the adhesive to which
the printing ink is attached, comprises sodium hydroxide and
water in admixture in the proportions of approximately five
parts of sodium hydroxide to lOO parts water, by weight.
Effectiveness of the solution is improved if the solvent is
heated to ~rom 40Co to 60C~ One part of hydrochloric acid to
lOO parts of the water may advantageously be added to the solu-
tionO The admixture given assumes a concentration of in excess
- of 70% with respect to both the sodium hydroxide and hydro-
chloric acidO Following application of the paper solvent, the
dissolved paper is removed from the laminate by scrubbing and
rinsing with water.
When the laminate is dry it is either recycled through
the above described stages of the process for the application of
additional layers of adhesive and printing ink thereby to in-
crease the density of the representation produced by the printing
ink, or a backing layer is applied to produce a finished product
In the event of a recycling of the laminate, no initial
adhesive coating is applied to the laminate already produced. ~ ;
During this recycllng the adhesive solvent is applied to the
existing surface of the substrate carrying the printing ink and
to a dry even continuous coating of vinyl glue applied to the
printed information surface of the printed paper concerned,
before this printed paper is pressed into contact with the
existing laminate, to produce laminate comprising in order sub~
strate, adhesive, printed information, adhesive, printed in-
formation and paper. It will be appreciated that the printed
information involved in the first steps of the process is
--11--
.. . . . .. .
: . ' ,.' ., , , : .',, ~ . : :
,. . : ,. :: - ~ . , , ,, ~ -.
' , .': ' ' ' . ' ' ,'.', ' ', ' .,'', ' ' ' :' ,'' ' ''''' ,,. ~ ' ' ':
3~il8
identical with that used in the recycling and that the super-
imposed layers of printed information are carefully arranged in
registration with one another thereby to appear as a single
printed image when viewed in a normal mannerO Apart from the
omission of the step of applying adhesive to the laminate, the
recycling steps of the process are substantially identical with
those previously carried out up to and including the removal of
the paper layerO
The example of the invention with respect to which
. "
the present process is described will usually require two re-
cycling stages in order to produce a desirable density of color
in the printed information formed by the printing ink. With
these two stages of recycling, three layers of printing ink are
produced and the product, after application of a backing layer,
will in cross-section appear as diagrammatically represented in
~igure 4O A product such as this is suitable for back lighting
to produce an illuminated display of high quaIityO In some
instances only one recycling stage will be required and in cases
where the substrate or backing layer are of an opaque material
te.gO, marble), recycling may be unnessary as the transfer of a
single layer of printing ink may suffice to produce the desired
density of color in the printed information transferred.
When the desired numb~r of superimposed layers of
printing ink have been transferred to the substrate and the
paper removed, the resulting laminate has a backing layer applied
in order to protect the superimposed layers of printing inkO In
this example the backing layer ls of the same material as the
substrate and utilization of the same adhesive used in the
laminating process is appropriate for its application. An even
continuous coating of the adhesive is formed on the backing
-12-
.... . .. . . . . .
:, . . . ::
,
.. . . ~.
..
.
~083418
layer and allowed to dryO Solvent 9 consisting of approximatelyequal parts o~ benzene and toluene in admixture, is applied to
the printing ink surface of the laminate and to the adhesive
coating of the backing layer~ The activated surface of the
printing ink layer and the coating of the backing layer are
then brought into contact and pressure applied to produce a
uniform bond between the coatings of the backing layer and the
laminate and to squeeze any excess solvent from between the
laminate and the backing layer When the adhesive has dried,
the product is finishedO
While in the particular description of the apparatus
and process, reference has been made to substrates which are
planar and, by implication, to backing layers which are planar,
it will be appreciated that the apparatus and process may readily
be utilized by those skilled in the art, without further inven-
tive advance, to transfer printing ink onto single curvature
sur~aces. It will also be app~eciated that while the substrate
has, by implication, been regarded as a rigid substrate, that
the invention is also applicable to the transfer of printed in-
formation to ~lexible substrates, for example, polyvinyl chloride.
Exa~ples of materials from which the substrate andbacklng layer may be constructed are acrylic, acetate, polyvinyl
chloride, ~P.V.C.), polyester, "Celluloid"* "Nylon"* "Teflon",*
glass, marble, aluminum. I~ will be appreciated that when these
materials are used in combination to form a product according to
the present invention, except in products with the backing layer
omitted, the material of either the backing layer or the substrate
wlll normally be chosen to be transparent~
It will be appreciated that it is not essential for
the adhesive used in the coating of the substrate to be the same
B -13-
~ Re~istered Trade Marks
.. . . . . . .
- , . . , ' . : .: : , : :: ': . . . : . .
.. . . .
-- ~834~
as the adhesive used for the coating of the printed paper and
that the adhesive used to coat the backing layer may be
different from that used on the substrate and/or the printed
paper. The only requirement is that the adhesives which come
into communication with one another are compatible (iOeO, will
bond or unite together to form a permanent transparent joint).
As used herein the term "transparent adhesive" means
an adhesive which is transparent when dry.
Reference is made herein to activation of the exposed
surfaces of adhesive coatings by the application of a solvent.
~his "activation" means placing the exposed surface of the ad-
hesive coating into a condition in which it will bond or unite -~
with another such activated surface of an adhesive coating, upon
applic~tion of pressureO
While the particular description of apparatus and
process refers to the provision of a backing layer which is
attached by adhesive to the laminate préviously produced, it
will be appreciated that the printed information and adhesive
layers exposed on one surface of the substrate may be protected
by a layer of material formed thereon by any well known means,
including the spraying of a protective coatingO
While the particular description refers to the removal
of the solvent and dissolved paper backing by scrubbing with a
brush, it will be appreciated that the scrubbing step may be
achieved by other means, for example, ~ets of liquid or gas,
and that the term "scrubbing" is to be construed as including
these.
Commercially available polyvlnyl acetate copolymer
adhesives provide satisfactory results on substrates and backing
layers of acrylic, acetate and P.VOC. and may also be found
-14-
.... ~
,: . . ~ ~ .!.:. `, . .
' '` . : ~' , ` ` ,; ~ ~` ' ` " ' . `
- , ~ ` ' '
, ~ . , ' ` .
! .
. .
'
appropriate for use when the substrate or backing layer is con-
structed of glass, metal or porcelain. Polyvinyl acetate co-
polymer adhesive also provides the desired adhesion to the print-
ing ink of the printed information and is therefore appropriate
for use as the coating on the printed paper.
An alternative adhesive for use with acrylic, acetate
or P.V.C. substrates and backing layers, and for use on the
printed paper, consists of an admixture of cellulose acetate,
acetone, rosin, polystyrene and a solvent or solvent mixture.
While a wide range of proportions of these materials will result
in an effective adhesive, it has been found that the following
proportions by weight produce an adhesive having the desired
characteristics for the process concerned:
Cellulose Acetate - about 12 to about 20 parts
Acetone - about 36 to about 60 parts
Rosin - about 3 to about 5 parts
Polystyrene - about 3 to about 5 partsO
To this desired admixture is added appropriate quantity of a
suitable solvent or solvent mixture to permit the application
of the adhesive in a desired manner to produce an even con-
tinuous adhesive coatingO Where the adhesive is to be sprayed
to form the coating, from about 5 to about 20 parts of solvent
to each 10 parts of the admixture produced from the above pro-
portions of cellulose acetate, acetone, rosin and polystyrene
has been found effectiveO
The optimum admixture of constituents for the ad-
hesive, including the solvent, will depend on the method of
appllcation, the time perlods involved in preparation on appli-
cation of the adhesive and ambient conditions (particularly
temperature). With the process particularly described and on
-15-
.;,
. . , -- . ,, .~ .
: , ~
. . , .:
, ~
.
~ 83~L18
_
the basis of an ambient temperature of 20C., the following ad-
mixture in proportions by weight is prererred~ :
Cellulose Acetate - 16 parts
Acetone - 48 parts
Rosin - 4 parts .
Polystyrene - 4 parts
Toluene (solvent) - 72 parts,
in thls preferred ~orm o~ adhesive toluene, the preferred solv-
ent, is utilizedO
T~le solvent used to activate exposed surfaces of ad-
hesive coatings ~ormed from cellulose acetate, acetone,-rosin,
polystyrene, and a solvent, may be any suitable solvent. How-
ever, benzene and toluene in admixture, preferably ln equal
parts by weight? has been ~ound appropriate ~or use at amblent
temperatures above 15C. At temperatures below 15C. chloro- .
benzene may be added in the proportion of 1 part chlorobenzene to
20 parts by weight of the admixture of benzene and toluene~
When the material of the substrate or backlng layer
is aluminum, marble, polyester, "Celluloid"* glass, "Nylon"*, or
:20 I'Te~lon"* the above adhesive containing cellulose acetate, :-acetone, rosin and polystyrene may be utilized in the propor- .
tions specified by ranges and in the speci~ied pre~erred form
providing a sultable solvent ls utilized. The solvent ls utll- :
ized in the range o~ proportions and preferred proportion
specified above and pre~erably is ethyl alcohol.
When an adhesive ~orm utilizing alcohol as à solvent
is used, the solvent ~or activating the exposed sur~aces of the
adhesive is any suitable solvent and is preferably an admixture
o~ ethyl alcohol and methyl ethyl ketone, preferably in equal
parts by weight~ Again, where the ambient temperature is below
*Registered Trade Marks -16-
' ~3 ,
- .
- , ~
.
., . ; . , : . , ;
:, . . .
: . .
~L~834~
15C., chlorobenzene in the proportion of l part to 20 parts
by weight o~ the admixture o~ ethyl alcohol and methyl ethyl
ketone is added.
A dilute caustic soda solution is an efective solv-
ent for paper and this may have the proportions of between 400and 600 grams of caustic soda flakes dissolved in 10 liters of
water. This dilute solution is preferably used at a tempera-
ture o~ between 40C~ and 60C. A pre~erred paper solvent is a
caustic soda solution to which a quantity of hydrochloric acid
has been added. This admixture may comprise 400 to 600 grams of
caustic soda flakes, 80 to 120 cubic centimeter of hydrochloric
acid and lO- liters of water. A preferred admixture is 500 grams
of caustic soda flakes, 100 cc of hydrochloric acid and 10 liters
of water.
It will be appreciated that in a case where the paper
carrying the printed information is water-soluble the paper solv-
ent may preferably be water.
It will also be appreciated that the- adhesivej adhesive
s~lvent,paper solvent and rinse liquid may be applied by any
appr~priate means including, for example, spraying, brushing or
dipping.
The adhesive utilized in the process and apparatus
herein described is an adhesive or adhesive combination which
will adhere to printing ink used in the production of the
printed paper used and to the substrate involved.
- 17 -
~ ,,,
. : , ' ',': ' ~,:: ' ,'' ' . . ,,, . ' '
- - . . . . : , , ~: , , . ., ., . . . . , ~ ,, , . :
