Note: Descriptions are shown in the official language in which they were submitted.
_ AZ-739
~045872
SURLAY PROOFING METHOD
This invention relates to a process for making a
multicolored reproduction combining overlay and surprint
characteristics.
; Background and Prior Art
In the graphic arts, it is desirable to produce
a four or more color proof to assist a color etcher in
correcting a set of color prints prior to using them to
produce color plates and also to reproduce the color quality
that will be obtained during the printing process. The
proof must be a consistent duplication of the half tone, and
should neither gain nor lose color. Visual examination of
a color proof should show the following characteristics:
1. Defects on the negative.
"' 2. The best color rendition to be expected from press print-
ing of the material.
3. The correct gradation of all colors and whether grays
are neutral.
4. ~he need, if any, for subduing one of the colors and/or -
giving directions for altering the film negatives before -
making the printing plates.
A method of transferring colored images has been ~;
applied to the preparation of a color proofing sheet in mul-
~` ticolor printing. Thus, color proofing sheets, for multi-
colored printing, have heretofore been made by using a prin- -
; ting press or a proof press while taking all the steps ne-
cessary for actual multicolor printing, but such a conven-
tional method of color proofing has been costly and time
: :
AZ -7 3 9
104S87Z
consuming.
Photographic processes have also been used, espe-
cially photographic processes using photopolymers. There are
two known types of photographic color proofing methods; name-
ly, the surprint type and the overlay type.
In the overlay type of color proofing method, an
independent transparent plastic support is used for producing
a print of each color separation film by applying a photo-
sensitive solution of the corresponding color, and a plural-
ity of such supports carrying prints of corresponding colors
are then superposed upon each other on a white sheet to pro-
duce a color proofing sheet. The overlay type of color proof-
ing method has the disadvantage that the superposed plastic
supports tend to darken the color proofing sheet, and, as a -
result, the impression of the color proofing sheet thus pre-
pared becomes vastly different from copies actually obtained
by a conventional printing press or a proof press. Its pri- --
mary advantage is that it is quick and can serve as a pro-
gressive proof by combining any two or three colors in re-
gister.
In the known surprint type of color proofing me-
thod, a color proofing sheet is prepared by successively
producing prints of different colors from different color
separation films, r`espectively, by utilizing a single opaque
support by applying toners, or by applying photosensitive
solutions or coatings of photopolymers of corresponding co-
lors on the opaque support in succession. Examples of some
of these approaches are: U. S. 3,671,236 (317)-Transfer
-2-
AZ-739
1~4587Z
color key and U. S. 3,136,637 (3M)-Color key An advantage
of the surprint type of color proof is that the color satur-
ation is not influenced by the plastic support. This method
more closely resembles the actual printing process and elim-
inates the color distortion inherent in the overlay system.
- Various processes for producing copies of an image
embodying photopolymerization and thermal transfer techniques
are known. See U. S. 3,060,023; 3,060,024; 3,060,025;
3,481,736; 3,607,264. In these processes, a photopolymeri-
zable layer coated on a suitable support is exposed, image-
wise, to a process transparency. The surface of the exposed
layer is then pressed into contact with the image receptive ---
surface of a separate element and at least one of the said
elements is heated to a temperature above the transfer tem-
perature of the unexposed portions of the layer. The two el-
ements are then separated, whereby the thermally transferra-
ble, unexposed, image areas of the composite transfer to the
image receptive element. If the element is not precolored,
the tacky unexposed image may now be selectively colored
with a desired toner. The colored matter adheres, preferen-
tially, to the clear unpolymerized material. The lamina-
tion, exposure, and developiTIent steps are carried out for
the respective colors, in sequence, thus making these pro-
cesses time consuming.
U. S. 3,574,049 (1971), issued to Trentesaux-
Toulemonde, provides a transfer process, wherein it is sta-
ted:
"The present invention provides a
.
--3--
~, ' '
.
, . :-: .
AZ-739
1~)4587Z
transfer process for printing a
design on a final support which
comprises (a) printing a design
onto a temporary support, (b)
super-imposing the temporary
support and the final support,
(c) applying heat and/or pres-
sure to the super-imposed struc-
ture formed in (b), and (d) sepa-
rating the temporary support from
the final support which retains
the printed design, the affinity
of the material of the design
for the temporary support being
lower than its affinity for the
final support.
The temporary support may com-
prise a coating, called a trans-
fer coating, of a material for
which the material of the design
has an affinity lower than its
- affinity for the final support,
and preferably the difference
- between the two affinities also
increases with increasing tem-
pera;ture."
' In the claims, the temporary support is coated on its face
with a transfer coating, (a release layer) of ethylcellulose
~ which bears a pigmented film of vinylchloride polymers or co-
polymers. The teachings of the above patent allow only (a)
a single transfer which is not feasible for multiple transfer,
(b) transfer of vinylchloride polymer systems only are possi-
ble, and (c) the transfer is made possible by a thermally sen-
., .
sitive release layer present between the image and the support.
Furthermore, this process is not photographic, but relies upon
impression printing. Finally, the polyvinylchloride printed
image i9 transferred only to metallic aluminum. ~o reference
i8 made to transfer papers or plastics.
In U. S. Patent 3,721,557, issued to Process Shizai
Co., Ltd., Tokyo, Japan, a method of transferring colored ima-
.
; .
.
AZ -7 3 9
104S872
ges is claimed which provides a stripping layer coated be-
tween the photosensitive element and the support. When the
photosensitive layer is exposed to actinic light and devel-
oped, the more soluble portions are selectively removed to
produce a visible image. The image-carrying support is
pressed against a suitable adhesive coated receptor member
and, subsequently, the carrier support sheet is stripped to
accomplish the transfer of the image. A fresh layer of ad-
hesive is applied to the receptor for each subsequent trans-
fer. The two extra steps, (1) of coating a stripping layer
between the photosensitive coating and the support, and (2)
application of adhesive between each image, are time-consum-
ing and costly. In addition, the image build-up in a four-
color proof is so thick that it gives rise to moire patterns
and secondly the image is so distorted~that the proof cannot
be any cleaner or truer than an overlay-proof.
Most of the cited processes are po9itive working
systems. Some require costly and sophisticated transfer
equipment and depend on sequential lamination (pressure and
heat), exposure, and transfer (or delamination of the poly-
meric element) processes for each color used. This, of
course, makes *he total process very time consuming. The
use of addition polymerizable elements for the production
of relief images was first revealed by Gates (British Patent
566,795 - 1945) but this invention was not found to be prac-
tical. Photopolymer elements of a more practical and pre-
ferred type relating to this invention are disclosed in
Plambeck, U. S. Patents 2,760,863 (1956), 2,791,504 (1957),
~.
-5-
,
1045872 _ ~ _ AZ-739
3,218,167 (1965~ and 3,458,311 (1969).
Finally, u. S. 3,775,113, issued to Bonham et al,
covers a process for transferring positive images to receptor
sheets. It should be noted here, that this process is for
positive-working systems rather than negative-working sys-
tems and the photosensitive materials utilized are photoly-
zable rather than light-hardenable. In fact, it is stated
in the patent that "A further objection to processes utili-
zing transfer sheets having a free radical photopolymeriza-
ble layer is that such layers are susceptible to oxygen in-
hibition and must be protected by a cover sheet or protective
layer."
The distinguishing features of our invention, as
' wi.ll be shown in more detail below in the description of the
invention, however, are that the unexposed negative-working, .
photosensitive layer is not thermally transferrable and the
exposed negative-working, photosensitive layer is thermally
: transferrable without the aid of a stripping layer between
the negative~working, photosensitive layer and the carrier
. 20 sheet.
One objective of this invention is to utilize a
truly negative-working system in which color separation ne-
gatives are used for the exposure step and the light exposed
images obtained are composed of light hardened matter.
. A further objective, when using photopolymerizable
layers, is to~expose the light sensitive coatings through
the transparent polyester support in such a way as to produce
a thin layer of crosslinked coating next to the support -~ -
sheet and overlaid with enough uncrosslinked coating, or other ~:
. ....: .
- :: :. ,. . . : . , : ~ - : :
-
AZ -7 3 9
~ 104587Z
oxygen impervious coating, so that polymerization of the -
light sensitive coating may proceed.
Another objective of this invention is to provide
a new and practical proce~s for transferring multicolored
photopolymerized images from transparent overlay foils to
a paper type receptor sheet.
A still further objective of this invention is to
carry out the transfer process, under pin register, and at
a low uniform pressure and temperature so that high resolu-
tion of the image is obtained.
Another objective is to permit the use of any water
resistant sheet or foil as a suitable carrier overlay, where-
in the proper image adhesion is obtained both before and
after development.
~, A further objective is to provide a suitable adhe-
sive transfer process so that even porous paper may be used
for the receptor sheet without starving the surface for ad-
hesive.
Still further objects will be apparent from the
description of the invention.
Summary of the Invention
In the use of photopolymerizable compositions, a
colored photosensitive layer is cast on a semi-rigid, trans-
parent, support film. The layer consists of:
a. at least one organic macromolecular binder, with `
pendant acid groups,
b. at least one multi-functional, unsaturated, com-
pound capable of forming a polymer by addition
- ' ~'' . '.:
: ' ' ~ .' ' . - ' -.` , : ' ' ~
. .
.
.
AZ-739
11~)4587Z
polymerization, usually called monomer,
c. an addition polymerization initiator activated by
radiation,
d. a light stable colorant taken from the class of
light stable dyes or pigments. The colorant should
be one such that when it is transferrea to the re-
ceptor, its color values approximate the color
values that will be produced by the printing ink
that is to be used. Under these conditions, the
color proof will simulate the true printing,
e. optionally, a sensitometric regulator,
f. and, optionally, a hydrogen donor.
The coating is cast at a coating weight of between 2 and
20 g/m2, preferably 4.0-10.0 g/m2. It is then dried at
40-100C in an air oven for an interval of time until the
coating is dry to the touch. The dry coating may then be
left as is or overcoated with a dilute water solution of
polyvinyl alcohol or some equally satisfactory oxygen bar-
rier system. The coating is then exposed to W radiation
in a typical exposure unit. It is exposed through the
appropriate color negative, which is placed on the film
side (support side) of the composite. The exposed coatings
are developed with an aqueous alkali developer, washed with
water, and dried. The above steps are repeated as often as
necessary with differently colored elements ul~imately lead-
ing to a multicolored overlay system. To transfer the posi-
tive images on the overlay supports to a paper receptor or
similar support, a release sheet is first coated with a
' . ,, , ~ ~, . . ; ,
~4587Z
suitable acrylic, adhesive binder. The film is dried to the
touch in an air oven and then transferred to the paper of one's
; choice by bringing the release sheet supported film and paper
receptor sheet together under nominal pressure and at elevated
temperature. The composite is cooled before stripping away the
release sheet. Then, the image bearing support film is brought
together with the adhesive coated, support sheet (image to
adhesive) again under nominal pressure and at elevated temper-
ature. The composite is cooled before stripping away the overlay
film lesving the image embedded in the adhesive on the receptor
sheet. Each additional image is registered on the preceding
image and transferred in the same manner.
In one particular aspect the present invention
provides a method of making a multicolored reproduction, com-
prising exposing a colored, photohardenable layer on a support
sheet through a color negative, developing the layer to remove
non-image areas and leave image areas on said support sheet,
coating a receptor sheet with an adhesive by contacting said
receptor sheet with an adhesive coated release sheet at a
temperature and pressure sufficient to transfer said adhesive
to said receptor sheet, removing said release sheet, contacting
said image areas on said support sheet with said adhesive coated
receptor sheet at a temperature and pressure sufficient to trans-
fer said image areas to said receptor sheet, removing said
support sheet, and contacting said receptor sheet again at least
one with a support sheet having transferable image areas thereon
in order to transfer at least one additional colored image to
said receptor sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a coated base sheet, `
Figure 2 shows exposure of the base sheet through a
negative,
j,,, _ g _
~ A7~
104587Z
Figure 3 shows the hardened image areas on the base
sheet after removal of the unhardened non-image areas,
Figure 4 shows a release sheet with adhesive,
Figure 5 shows lamination of the release sheet to
paper stock,
Pigure 6 shows the release sheet being peeled off
the paper stock,
Figure 7 shows lamination of the paper stock to the
developed base sheet,
Figure 8 shows the base sheet being peeled off the
paper stock to transfer the image areas to the paper stock,
and
' ~
.....
: 30 :
~ 9a- :;
_. .
t~
.
AZ-739
1~)4S87Z - /o _
Fig. 9 shows a second base sheet being peeled off
the paper stock to transfer a second color image area to the
pa per stock.
Detailed Description of the Invention
In general, this invention comprises an image re-
production and transfer process in which an element is pro-
duced comprising, in order, (a) a carrier support, (b) a pho-
tohardenable layer, preferably including a photopolymerizable
layer, and (c) an adhesive coated receptor sheet ultimately
laminated to the photohardened layer on the carrier support.
The term "photopolymerizable", as used herein, re-
fers to systems in which the molecular weight of at least one
component of the photosensitive layer is increased by exposure
to actinic radiation sufficiently to result in a change in
the rheological and thermal behavior of the exposed areas.
Those photopolymerizable systems found suitable for this use
(1) may be present alone or in combination with a compatible
binder or (2) such a photohardenable group may be attached to
a polymer backbone. The group becomes activated on exposure
to light and may then crosslink by reacting with a similar
group or other reactive sites on adjacent polymer chains.
Where the pendent photohardenable group is capable of addi-
tion polymerization, the total chain may involve addition of
many units initiated by a single photochemical act or as few
as two units to form what is known as a dimer. Where a pho-
tohardenable molecule has more than one reactive site, a so-
called crosslinked network of molecules is produced.
The term "exposed" as used in this invention is
intended to cover the image areas whose solubility in water
.
'
104S872 ~ AZ-739
and weak alka li is significantly less because of the actinic
light-induced increase in molecular weight of the photohar-
denable molecule, thus allowing the unexposed or partially
exposed areas to be removed by greater solubility in water
or weak alkali.
In the preferred photopolymer image reproduction
element, the carrier support should be a material which is
chemically and thermally stable under the process conditions
of the invention, flexible and transparent to actinic light.
Thin films of polyethylene terephthalate have been found
most acceptable. However, copolymers and terpolymers of
methyl methacrylate, modified celluloses, 6,6 Nylons, 6,
12 Nylon, 6 Nylon, polyvinyl acetates and alcohols may be
used.
The composition of the binder-, monomer-, initia-
tor-, colorant-, light-sensitive-coating may be selected
from the following components but is not necessarily limit-
- ed to the named materials:
Binders:
:~ 20 Composition
MMA/MAA (90/10)
MMA/MAA (85/15) : ~:
HEMA/St/MAA (72/10/18)
- ~MA/St/~A (60/10/30)
HEMA/St/MAA (55.6/12.7/31.7) :
MMA/~IEMA/MAA (12.5/62.5/25) ~: -.
- MMA/EA/MAA (75/10/15)
MMA/EA/MAA (65/20/15)
MMA/B`/M~A (65/20/15)
,
,. . : . . ~ . .. . ..
. . . .: .
104S8 ,~Z AZ-739
MMA = Methyl methacrylate EA = Ethyl acrylate
St = Styrene BA = Butyl acrylate
HEMA= Hexyl methacrylate MAA= Methacrylic acid
The preferred binders have an acid number between 30 and 200
(preferably 80-200) and a viscosity,-at 25% solids in ethyl
cellusolve, of 75 cps to 200 cps (preferably 100-150 cps) at
22C. (Cannon-Fenske method - C-661 tube). These composi-
tions are partially thermoplastic.
Light Sensitive Monomers:
Suitable ethylenically unsaturated compounds which
may be used in this invention include unsaturated esters of
polyols, particularly such esters of the alpha methylene
carboxylic acids, e.g. ethylene diacrylate, diethylene gly-
~ col diacrylate, glycerol triacrylate, mannitol polyacrylate,
- polyacrylates, ethylene dimethacrylate, 1, 3 propanediol di-methacrylate, polyethylene glycol dimethacrylate, 1,2,4 bu-
tanetriol trimethacrylate, trimethylol ethane triacrylate,
1,4 benzenediol dimethacrylate, pentaerythritol di-, tri-,
and tetramethacrylate, pentaerythritol di-, tri- and tetra-
acrylate, dipentaerythritol polyacrylate, 1, 3 propanediol
diacrylate, 1, 5 pentanediol dimethacrylate, the bis acry-
lates and msthacrylates of polyethylene glycols of molecular
weight 200-400 and the like; unsaturated amides, ethoxylated
bisphenol A, particularly those of the alphà methylene car-
boxylic acids, alpha, omega diamines and oxygen interrupted
omega diamines, such as methylene bis acrylamide, ethylene
bis-methacrylamide. The preferred monomeric compounds have
more than one ethylenlcally unsaturated group. The amount
-12-
.
' ,. ,
~04S87Z / 3 AZ-739
of monomer added varies with the particular binder used.
Initiators:
A preferred class of addition polymerization ini-
tiators, activatable by actinic light and thermally inactive
at and below 150C, are the substituted or unsubstituted
polynuclear quinones, which compounds have two intracyclic
carbonyl groups attached to intracyclic carbon atoms in a
conjugated six membered carbocyclic ring, there being at
least one aromatic carboxylic ring fused to the ring con-
taining the carbonyl groups. Suitable such initiators in- - -
clude 9, 10 anthraguinone, l-chloroanthraquinone, 1, 4 naph-
oquinone, 2, 3 benzanthraquinone, 2, 3 diphenylanthraquinone
and 1, 2, 3, 4 tetrahydrobenzanthracene-7, 12-dione. Other
photo initiators that are useful in this process are diacetyl
benzil, benzoin, 9-phenylacridine, 2, 3 di para methoxy phenyl
quinoxaline, diacetyl benzil, and benzoin methyl or ethyl
ethers. The initiators of this invention are most effective-
ly activated by light of about 300 to 500 nanometers wave-
. ~ , .
length. Still ~ther initiators may be used without depart- -
ing from the spirit of this invention.
Colorants:
The colorants used may be either pigments or dyes.
If pigments are used, these are best incorporated into the
, coating formulation by ball milling the pigment and appro-
priate wetting agents into the base film forming resin, then
adding this concentrate, with stirring, to the coat ing formu-
lation. Suitable pigments are Royal Spectra Blac ~(City
Service Co.), Yellow DGH 23 (American Hoechst Company), Hos-
taperm Pink ~ (American Hoechst Company), Permanent Blue
15-1020 (American Hoechst Company), etc. Among the dyes
~ A~
. . . . .. . .. . . . . . . . - -
~ AZ--739
104587~'
that arq suitable are:
Victoria Pure Blue FGA-BASF
Rhodamine 6GDN-Extra-Dupont
Interplast Pink 5 BLG-Intracolor~
Auramine 0 Concentrate-BASF
Hostadye Yellow Fast R~-American Hoechst Co.
Neozapon Fiery Red G-BASF~
Atlantic Brown #4~- Atlantic Chemical Co.
~eozapon Red BE-BASF
Grasol Fast Yellow 3~GL-Ciba-Geigy
Grasol Fast Black RL-Ciba-Geigy
Grasol Fast Rubine 2 BL~-Ciha-Geigy
Spirit Black #3-Dupont
Crystal Violet 6B-Dye Specialties Corp.
Crystal Violet Base - KALLE A.G.
Acetasol Green BLS
Neozapon Red BB-BASF~
Astra Malachite Green Crystals~- Verona
Dye Co.
Neozapon Yellow GG -BASF
Astrazon Blue FFR -Verona Dye Co.
Spirit Soluable Fast Yellow R - BASF
Astrazon R`ed GTL - Verona Dye Co.
Rhodamine B Extra - Dupont
Basic Black K~R - Allied
Victoria Blue B - Dupont
Victoria Cyan - BASF
Astrazon Red GB BASE-Verona Dye Co.
~ . '' - '
;` -14-
.. , , ,. . .: ~ .
104S872 ~ AZ-739
Auramine - Dupont
Astrazon Red BBL Base - Verona Dye Co.
Astrazon Black R - Verona Dye Co.
~strasol Yellow Brown - 2 GL~- Verona Dye Co.
Astrazon Orange R - Verona Dye Co.
Grasol Fast Pink 5 BL~ Ciba-Geigy
Solvent Black DS-2906 - Dye Specialties
Astrazon Black WRL - Verona Dye Co.
Astrazon Pink FBB Base - Verona Dye Co.
Dyes and pigments may be selected to match printing inks.
Sensitometric Regulators:
The sensitometric regulators used in this invention
may be selected from the substituted benzophenones. They are
. compatible with either the components of the light sensitive -~
coating system or, in some cases, may be included in the pro-
tective coating of a polymeric release layer. They have rela-
.
tively high melt temperatures (100C-350C) and inhibit long
term degradation of the print. Those inhibitors that msy be
used are 2,2'dihydroxyl-4, 4' tetrahydroxybenzophenone, 2, hy-
droxy-4-methoxy-benzophenone-5-sulfonic acid and sodium 2,
2'dihydroxy-4,4'-dimethoxy-5-sulfobenzophenoné. One may also
use the alkylated phenols and bisphenols, such as the Irganox~
1076 and 1093 (Ciba-Geigy), the Ionols CP and CP40, and the
Advastalis 401 and 402 (Deutsche Advance Production).
Hydrogen Donors: ~
The hydrogen donors used in this invention are added
for the purpose of improving the efficiency of the initiator
which, in turn, improves the polymerization rate of the mono-
mer. Among those compounds found useful for this purpose, in
i~ this invention, are hexyl di ethylene glycol ether, methyl
.
, . .. . ~ , .. , ~, : :
AZ-739
1~)45~72
phthalyl ethyl glycolate, and ethyl phthalyl ethyl glyco-
late. However, these additives do not appear to noticeably
affect the efficiency of faster initiators.
Polymeric Release Layers:
The polymeric components useful in this invention,
which are nontacky at vacuum exposure conditions, include
cellulose, cellulose esters, cellulose ethers, polyvinyl
alcohol, polyvinyl alcohol-formaldehyde and butyraldehyde
acetals, methoxy-methyl polyhexamethylene adipamide, gela-
tin, polyethylene and pc>lypropylene.
Adhesives for coating the image receptor sheet,
used in this invention, are of the clear to slightly trans-
lucent hot melt type and are activated at temperatures of
between 200F-260F and laminator roll pressures of 20 psi -
500 psi. Preferred molecular weights of the adhesives are
between 10,000 ond 50,000 and show viscosities (ASTM-D-2857
Dilute Solution Viscosity of Polymers~annon-Fenske ~rube
C-661.) at 25,6 solids in ethyl cellosolve of 80 cps - 170
cps. Among those polymeric materials found suitable for the
purpose of this invention are: Methyl methacrylate/metha-
crylic acid copolymers (90/10 pts by wt - 70/30 pts by wt),
Hexyl methacrylate/styrene/methacrylic acid ~72/10/18), me-
thyl methacrylate/hexyl methacrylate/methacrylic acid (12.5/
., ~ '
; 62.5/25), methyl metkacrylate/ethyl acrylate/methacrylic acid
(75/10/15), methyl methacrylate/ethyl acrylate/methacrylic
acid (65/20/15). Also, Rohm ~ Haas' Acryloid resins may be
used: they are Acryloids(~-10, B-82, B-72, B-66, B~8 N and
A-10 and are believed to be butyl methacrylate polymer, methyl
. A~ -16-
. : :
AZ-739
104587Z
methacrylate copolymer, ethyl methacrylate copolymer, methyl
bu-tyl methacrylate copolymer, methyl methacrylate copolymer
and methyl methacrylate polymer, in that order. These mate-
rials may be used singly or in combination. Other similar
polymers may be used for this purpose without departing from
the scope and intent of this invention.
For a better understanding of the invention, refer-
ence is made to the drawings. In accordance with Fig. 1,
the polyester base sheet 3 is coated with the light-harden-
able, uncrosslinked photopolymer system 2 which, in turn, is
over-coated with an optional oxygen barrier system 1. In
Figure 2, the exposure is made through the screened color se-
paration negative 5 (emulsion down), optional oxygen barrier
1, light-hardenable photopolymer 2 and polyester base 3, in
that order, using register pin 6. According to Fig. 3, the
unhardened areas are developed away leaving the first color
of the light-hardened polymer 4. In Fig. 4, the thermoplas-
tic adhesive 8 is applied to a release sheet 9 and dried to
remove solvent. Fig. 5 shows the adhesive carrying release
sheet 9 being laminated to the desired paper stock 10 with
heat and pressure. The composite is cooled and, in accor-
dance with Fig. 6, the release sheet 9 is peeled away leaving
the adhesive 8 on the selected paper stock 10. The light-
hardened image 4 on the polyester support sheet 3 is then
passed through a heated laminator 11 to the adhesive coated
paper stock 13, using register pin 6, as shown in Fig. 7.
After the composite is cooled to room temperature, the car-
rier sheet 3 is stripped away, as illustrated in Fig. 8, lea-
-
~17-
: . . ..
104587Z AZ-739
ving the light-hardened photopolymer dots 4 embedded in the
adhesive 8 of the adhesive/paper composite 13. A second 12,
third, and fourth color is laminated in succession and in
similar fashion to that shown in Figures 7 and 8. This re-
sults, ultimately, in a four-color proof.
In the specific embodiment of the present inven-
tion, as illustrated in the Figures, use is made of four
light sensitive carrier sheets, each having a photo-sensi-
tive layer of negative-acting photopolymer, which becomes
in901uble to aqueous alkaline developer upon exposure to
actinic light. The photosensitive layers contain coloring
agents related to different primary colors: e.g. yellow,
magenta, cyan, and black. The colored films are exposed to
actinic light, through the appropriate color separation ne-
gative, either simultaneously or sequentially and then de-
veloped. The exposure and development processes can take
as little as 7 minutes, producing image overlays that may
be corrected individually, if needed, or viewed in four-
- color registry. The thermoplastic adhesive is applied on
the image receiving receptor sheet, made of paper, once
only and the colored images transferred, successively, by
heat and pressure.
The present invention provides a transfer process
for printing a semi-polvmerized element on an adhesive coat-
ed substrate using heat and pressure. This process appears
to be accomplished because (a) the adhesive adheres prefer-
entially to the paper stock and (b) because the hardened
photopolymer dots may be embedded in the adhesive at its
~ ' .
--18--
,~
1045872 ~ / q ~ AZ-739
softening temperature and held in place on cooling. The com-
patibility and stability o~ the two systems insure the system
against cohesive rupture and show excellent aging characteris-
tics.
The advantages of the present process are that it is
fast and easy to carry out. It is also possible to correct
individual colors in the overlay before transferring the ima-
ges to a common receptor sheet. These image areas, also, are
hard polymerized matter which do not have to be post-exposed
to preserve dot integrity, do not deteriorate on aging, and
may be transferred at the convenience of the user. Further,
the proofer and the customer may see the transferred print
on several possible pa~per choices before the press run is ac-
tually made.
Experimental
Example I:
Four light sensitive photopolymer solutions were
prepared by mixing the following components in Ray-Sorb, Erle-
nmeyer flasks tinted to preserve light sensitive materials.
Moderate stirring for about 1 hour with a magnetic stirrer
was sufficient to effect complete solution:
1. Methyl Methacrylate/Methacrylic Acid
Copolymer (85/15) 56.0 grams
t25% in Ethy1 Cellosolve)
(75.80 cps.ca. 30,000 M.W.)
2. HeXyl diethylene glycol ether1.0 grams
3. Trimethylol ethane triacrylate16.0 grams
4. 2,3 dimethoxy phenyl quinoxaline.55 grams
12 grams of the above composite were combined with each of
four pigment dispersions in the amount indicated:
'' ' ' . ' ' ' :.. ,~.. ' ' , -
104S87Z ~ ~ AZ-739
1. 1.8 grams Royal Spectra Black Dispersion
2. 1.95 grams Yellow DGH 23 Dispersion
3. 2.7 grams Hostapink E Dispersion
4. 1.5 gram~ Permanent Blue 15-1020 Dispersion
The dispersions used were prepared by American
~oechst's Pigment and Dyes Division and their composition and
method of preparation are listed below:
Components are by weight~ %, and in grams.
Dispersion
omp~onentsBlack` YellowMaqenta Cyan
Royal Spectra
Black 4.0
Yellow DGH 12.4
Hostaperm
Pink E 11.0 ;~
Permanent Blue
15-1020 12.3
MMA/MAA Resin
(30 M.W~)20.0 6.2 16.3 7.9
Aerosol OT
(75%) 1.3
Ganex P 904 ~l.O .8 .8
Monopole Oil
48 1.0
Ethyl Cello-
solve74.0 80.1 71.9 79.0
Procedure:
1. The pigment was wetted out in ethyl cellosolve with a
small amount of surfactant.
2. A 35X solution of the P(MMA/MAA) resin in ethyl cello-
; 30 solve was added for the proper pigment to binder ratio.
3. More ethyl cellosolve was added, as necessary, for proper
grind consistency.
4. The mix was then ground on a Red Devil "Quiokie" mill for
AZ-739
1~)4587Z
a satisfactory grind gauge rea~ing (ca. 30 sec . ) .
5. The resultant buttery mix was milled further and thinned
with solvent until it would screen freely through a gauze
cone.
The combination of binder system and pigment dispersion for-
med a complete coating.
Coatings corresponding to each pigment color were
cast on a 3 mil sheet of Mylar polyester film with a # 12
Mier rod and dried at 100C in an air oven. The drying sche-
dule was found to be somewhat critical at 100C to prevent
picking of the coating during exposure and at the same time
prevent loss of initiator due to the thermal drying treat-
ment. The following drying schedules were found suitable: ~
CoatingTime at 100C ~ ~ -
Black 7 min.
Yellow 7 min.
Magenta 7 min.
-
Cyan 9 min.
Coating weights were found to be about 4.6 gm/m . The four
pigmented coatings were exposed in a Nu Arc Platemaker expo-
sure unit in pin register through the appropriate color nega-
tive. The negative was placed on the polyester support side
of the composite so as to achieve images of the correct per-
-- spective for subsequent transfer. Exposure time was 1 unit
(3 min. 17 sec.) and each coating was developed with NAPS
Developer (American Hoechst Corp.) in 20-30 seconds.
Stepwedges of 5 ghosting to 7 were obtained for
black and yellow and 7 ghosting to 9 were obtained for ma-
-21-
Ar~ '
:
AZ-739
104587Z
genta and cyan. The four images on the transparent poly-
ester base, Melinex 0, were superposed in register to make
an overlay proof. The densities of the four colors were as
follows:
Color Cyan Magenta Yellow Black
_ilter Red Green Blue
R ~ F L E C T A N C E D E N S I T Y
Overlay, 4 layer 0.98 1.03 0.7 1.6
Surprint, after transfer 1.15 1.20 0.74 1.8
The hues were found to match the PMS colors closely. The
dot size of the individual colors corresponded closely to
the respective separation negative. Thus, dot fidelity was
preserved in the overlay rendition. Dot fidelity was pre-
served during transfer to form the surprint which possesses
the known expected advantages of a surprint. The use of
the photopolymer compositions of this invention gives one
the advantages of both overlay and surprint proofing systems
using the same color images.
Overlay Imaqe Transfer
A sheet of bonded printing paper was selected at
,.
random and coated (# 12 Mier rod) with a 30/0 solids aqueous
dispersion of a .5% oxalic acid catalyzed thermosetting
acrylic latex (Union Carbide UCAR-874). The treated paper
was cured 2' at 150C in an air oven and was effectively
sealed yet not rigid. The sealed sheet was then top coated
with a 25% solution of a methyl methacrylate/methacrylic acid
resin adhesive (24.5 cps) in ethyl cellosolve to a coating
weight of 20.8 g/m2. The coating was dried to touch in about
.
: A~ ~ -22-
AZ-739
104S872
40 seconds in a 100 air oven.
Transfers of the overlay image to the receptor sheet
were carried out by mounting the overlay, image side down, on
the adhesive coated receptor sheet, with pin registry, and
passing the composite through a DuPont C.T.F. laminator, at
pressures of about 20-25 psi and a roll temperature of 220-
230F. The polyester sheet was next to the hot roll and the
total composite moved through the laminator at about 5"/min.
The composite was then cooled to ambient temperature before
strippimg the polyester sheet.
Each color was superimposed on the other on the re-
ceptor sheet in similar fashion until all four colors had been
transferred. The order of transfer in this case was bla~k
down first, yellow next, magenta, and finally cyan, but this
is not considered critical and is at the optlon of the user.
Complete dot transfer was obtained with no visible curtailment
of the image rendition from the overlay to the print.
ExamPle II
The following formulation was stirred to complete
solution and then mixed with the pigment dispersions in the
same manner and in the same ratio as indicated in Example I:
1. Methyl Methacrylate/Methacrylic Acid Copolymer
78 cps 30,000 m.w.
85/15 (25% in Ethyl Cellosolve) 56.0 grams
2. Polyethylene Glycol Diacrylate (400)6.0 grams
3. 9 Phenyi Acridine .2 grams
The pigment dispersed coatings were applied to 3
mil., Melinex~0 polyester sheets (Imperial Chemical Industries,
Ltd.) at a coating weight of about 4.4 gms/m2. The coatings
~--.
~ 23-
. . . ....................... . .
.. . . . . . . ..
1()4587Z --~ Y -- AZ--73 9
were dried 2' at 60C and were found to be non-tacky to the
touch. A top coating of a water solution of polyvinylalcohol
(Elvanol 52~22 [E.I. duPont de Nemours] - 25 gms/l, Duponol
R. A. - 12.5 gms/l, Formaldehyde (30%) - 28.0 gms/l) was ap-
plied over the dried photopolymer coating at a coating weight
of about .2-.3 gms/m2 and dried for 2' at 60C.
The four colored foils were then exposed through
the appropriate negatives placed on the support film side of
the composite and exposed for the following time schedule:
Black - 2/3 Nu Arc unit
Yellow 2/3 Nu Arc unit
Magenta 1/2 Nu Arc unit
Cyan 1/2 Nu Arc unit
The exposed coatings were developed as shown in
Example I and clear, well-adhered images were obtained with
stepwedges of 5 ghosting to 7 for all colors. ~;
Preparation of Receptor Sheet
, .
A siliconized release sheet was coatea with a 35%
solution of Acryloid-B-48 N (in toluene) to a coating weight
of about 20.0 g/m2. The coating was dried for 2 minutes at
100C in an air oven.
~ sample of bonded printing paper was then selected
at random from stock and mated with the adhesive side of the
release sheet. A pressing iron was heated to 225F and passed
over the paper surface one to two times with moderate pres-
sure and cooled to room temperature. The release sheet was
then stripped leaving the adhesive film on the surface of the -
paper with minimum "strike-in" but good adhesion to the sur- -~
face.
A~
. .
.
. . ~ . - .
1~4587~ AZ-739
Transfer
:
In a manner similar to that described in Example I,
all four colors were superimposed in register to give a full
four color proof.
Example III
In a manner similar to Example I, the following
formulation was prepared and stirred to solution. As also
previously indicated, the parent coating media was pigmented
in the ratios indicated and these were stirred to excellent
dispersion in about 15 minutes:
1. Methyl Methacrylate/Methacrylic Acid Copolymer 85/15 25%
solution in Ethyl Cellosolve (78 cps 30,000 M.W.) 56.0
grams
2. Ethoxylated Bisphenol A 10.0 grams
3. 2,3 dimethoxy phenyl quinoxaline .2 grams
The pigmented coating media were laid on 3 mil po-
lyester support sheets, dried, top-coated with PVA, dried,
exposed, and developed as indicated in Example II. Step
wedges of 3 ghosting to 5 were obtained in all cases.
- 20 Transfers were made, as in Example I, with no
difficulty.
Example IV
A further example of this disclosure was formula-
~; ted and stirred to solution as in Example I:
1. MethyI Methacrylate/Methacrylic Acid 85/15 56.0
grams - 25% solution in Ethyl Cellosolve (24.5 cps)
2. Trimethylol ethane triacrylate 16.0 grams -~
3. Hexyl di ethylene glycol ether 1.0 grams
-25-
:
, ~ .
~04587Z AZ-739
4. 2,3 dimethoxy phenyl quinoxaline .55 grams
Again, the pigmentation ratios for the dispersions
and stirring procedures were followed as in Example I. PVA
top coating procedures, exposure procedures, and development
procedures were used as in Example II, except that the clear
but slightly tacky coatings that were obtained were exposed
on release paper to avoid picking.
Mark I~Cover Sheets, obtained from J & B Papers,
are supplied with a lacquer coating to obtain a high gloss,
high quality printing paper. A sample of this paper was coat-
ed with 20,000 molecular weight M~A/MAA eopolymer used in the
coating formulation at a coating weight of 20 g/m2 and dried
for 2' at 100C.
Image transfers were made in the C~F laminator at
temperatures as low as 200F, but with.simultaneous increases
in pressure to 35-40 psi. .At 250F transfer temperature, the
roll pressure could be reduced to about 15 psi. ':
Example V
., .
., .
. As in Example I, another thermoplastic photopoly-
merizable composition was made from the following components ;~
and stirred to complete solution: .
1. Styrene/Maleic Acid Copolymer 80/20 p :
20% solids in MEK (250 cps) . 70.0 grams
2. HeXyl diethylene glycol ether 1.0 gram
3. .Trimethylol ether triacrylate 14.0 grams
4. 2,3 dimethoxy phenyl quinoxaline .2 gram
In a similar manner to Example II, the 12.0 gram
portions of the mix were pigmented, coated on 3 mil Melinex~ i~t'.:
polyester film, dried, top coated with PVA, exposed and de-
Al ~ -26-
.. . . .. . .
1045872 ~ ~ AZ-73s
veloped. Step wedges of 7 ghosting to 9 were obtained in
each case and the images had good clarity.
Transfers were made ~y coating a Mark I cover sheet
with an MMA/MAA 85/15 copolymer. The copolymer had a 250 cps
viscosity at 25% solids.
In this example, a 6~ solids clear flux of the co-
polymer in ethyl cellosolve was made by stirring at 70C. A
sample of the flux was removed and a bead was made of the
flux and placed across one end of a bonded sheet of printing
paper. This was coverea by a release sheet and the composite
was run through the laminator at 230-240F and sufficient
roll pressure to produce a thin coating. The coating was al-
lowed to cool and the release sheet stripped. A .75-1.0 mil
c~ating was obtained with the bulk of the coating on the sur-
face.
Suitable image transfers were brought about by
transferring the images at 250-260F and 35-40 psi as in Ex-
ample I.
Example VI-
A thermoplastic photopolymerizable composition was
made from the following components and stirred to solution in
about one hour.
1. Methyl methacrylate/Ethyl acrylate/Metha-
crylic ~cid 75/10/15 56.0 grams
(25% ethyl cellosolve - 58 cps.)
2. Trimethylol ethane triacrylate 8.0 grams
3. Hexyl diethylene glycol ether 1.0 gram
4. 2,3 dimethoxy p~enyl quinoxaline .2 gram
All four colors were prepared, as in Example I, and
were coated on 3 mil Melinex~ film, dried, PVA top coated, ~ -
.. ~ ' .
-~~ AZ-739
1~4587Z
dried, exposed, and developed as in Example II.
Step wedges of 6 ghosting to 8 were obtained and
these overlays were found to have exceptionally good adhesion
to the polyester support.
25% adhesive solutions were made from the terpolymer
used in the photopolymerizable composition above and from an
MMA/EA/MAA 65/20/15 terpolymer. These were coated on Mark I
cover sheeting at a dry coating weight of about 20.0 g~m2 and
dried for 2' in an 100C oven.
An electrically heated hand roller (Emerald Film
Systems) was used to make the transfers. In the case of the
75/10/15 terpolymer, the transfers were made at 290-300F and
heavy hand pressure on the roller. The 65/20/15 terpolymer
transferred the images at about 270F and with heavy hand
; pressure.
ExamPle VII
A thermoplastic photopolymerizable composition based
on dyes was maae from the following components:
(All quantities are in gramsj
Component Cyan Yellow Magenta ~lack
Methyl Methacrylate/56.0 56.0 S6.0 56.0
Methacrylic Acid Co-
polymer (25% solids
78 cps)
Oxyethyl methacrylate 9.5 9.0 10.0 11.0
with 2,2,4 tri methylene
diisocyanate~2,2,4 tri
methylene diisocyano di
ethyl methacrylate)
9-Phenyl acridine .4 .7 .6 .8
Irganox 1076 .1 .2 - .1
Victoria Pure Blue.37 .01 - .27
FGA Dye (BAS~)
--28--
; ~ A~
- . . . . . . ...
~~ . i . ..
.... . - . . . . .. .
.. . .
1045872 AZ-739
Auramin FWA Dye (BASF) - .6 - .8
Rhodamin 6 GDN - .02 .3 .3
Extra (DuPont)
~eozapon Fiery Red G ~ - - .2 -
(BASF)
Intraplast Pink 5 BLG ~ .3
~Intracolor)
~he entire composition was stirred for about 1 hour
to effect maximum solution of the components and then each sys-
tem was filtered to remove unwanted sediment. The formulations
were then coated on polyester film (ICI's Melinex 0~ at a coat-
ing weight of 6.8 - 7.2 g/m2 and dried for 2' at 60C.
All four photosensitive coatings were exposed for
1/2 unit in the Nu Arc~exposure equipment. As in Example I,
the negatives were placed on the film support side and the pho-
topolymer exposed through the support film. ~ ~-
~ , .
An alkaline developar, EN-ll, supplied by -Kalle AG,
wa~ used and images with step wedges of 6 ghosting to 8 were `
obtained;
The receptor sheet was prepared for transfer as in
Example II-and processed through the laminator as in Example
I. Four color proofs were obtained with excellent dot rendi-
tion.
Example VIII
The following-photopolymerizable system, also based
on dyes, was prepared as indicated in Example VII.
(All quantities are in grams.)
Component Cyan Yellow Magenta BlacX
~ethacrylic acid/ 54.0 54.0 54.0 54.0
styrene/hexyl meth-
acrylate (28/22/50)
26% solids in MEK
-29-
. ~
104S872 - 3 o - AZ-739
ComponentCyan Yellow Magenta Black
Polyethylene glycol 3.75 3.75 3.75 3.75
diacrylate 400
Trimethylol Propane 1.25 1.25 1.25 1.25
Triacrylate
9 Phenyl Acridine .6 .6 .6 .6
Victoria Pure Blue .093
(FGA Dye(BASF)
Sudan Yello-~ Dye (Kalle) .367
Auramine 0 Dye (BASF) .127
Interplast Pink 5 BLG .044
(Intracolor)
Rhodamine 6 GDN-Extra .2
(Dupont)
Black Dispersion 8.8
(Example I)
It was found most convenient to dissolve the dyes in
methyl cellosolve according to the following concentrations:
Victoria Pure Blue Dye1.5g/100 gms. M.C.
Sudan Yellow5.0g/100 gms. M.C.
Auramine 02.6g/100 gms. M.C. ~ ~ -
Interplast Pink 5 BLG.6g/100 gms. M.C.
Rhodamine 6 GDN4.2g/100 gms. M.C.
These solutions were filtered and added to the for-
mulation in the amounts shown. The formulations were then coa-
ted on polyester film (I.C.I.'s Melinex 0~ at a coating weight
of about 9.2g/m2 and dried for 2' at 140C.
; All four photosensitive coatings were exposed for
(~)
1/3 of a ~uArc unit through the appropriate negative placed on ~-
the film support side of the coated carrier film.
An alkaline developer, EN-ll, sypplied by Kalle AG,
was used and images with step wedges of solid 4 ghosting to 7
.
were obtained.
.
.. ~ ' .. ",
- .
.
.
;
104587Z - 3 1 - AZ-739
A M~rk I '_over sheet, as described in Example IV,
was ~oated with Acryloia s-48N adhesive (Rohm & Haas) to a dry
coating weight of about 20g/m2 and dried for lS minutes in a
60C hot air oven and then 2 hours in a 100C hot air oven.
The developad images and receptor sheets were mated
and images transferred through the CTF laminator as in Example
I.
Four color proofs were o~tained with excellent dot
rendition.
Example_IX
The following thermoplastic photopolymerizable com-
positions were prepared and stirred for about 1 hour. The pig-
ment dispersions are those given before in Example I.
(All quantities are in grams.)
Component 1 2 3 4
! `
Methacrylic acid54.4 54.4 54.4 54.4
9tyrene/hexyl meth-
acrylate (30/10/60)
26~ solids in MEK
Polyethylene glycol 6.0 4.25 -4.25 4.25
diacrylate 400 ;
9 Phenyl acridine .2 .2 .2 .2
Black dispersion9.08
Yellow dispersion 7.4
Magenta dispersion 7.9
Cyan dispersion 4.93
All four colors were coated on 3 mil polyester film
(Melinex 0) at a coating weight of 9.S g/m2, dried for 2' at
60C and exposed for 1/2 unit in the ~uArc exposure unit.
.. . ~ .
The exposed films were developed with the alkaline
developer as in Example I and step wedges of S ghosting to 8
were obtained.
' , ,
.
- ~ AZ-739
lV45~72
Four color transfers were prepared by applying
Acryloid B-48 N~ dhesive to the M~rk I cover sheet as shown ,
in Example II and the transfer process was carried out as in
Example I.
Complete image transfer was obtained and dot rçndi-
tion was excellent.
Example X
The following thermoplastic photopolymerizable com-
positions were prepared and stirred to complete solution in
about 1 hour. Dispersion9 are those previously given in Exam-
ple I.
(All quantities are in grams.) -~
Component 1 2 3 4
Hexyl methacrylate/sty- 54.4 54.4 54.4 54.4
rene/methacrylic acid
~S5.6/12.7/31.7)Acid No_
190-26% solids in MæK
Polyethylene glycol 4.25 4.25 4.254.25
diacrylate 400
.
9 Phenyl Acridine 0.5 0.5 0.5 0.5 ~ ~
Black dispersion 9.08 -
Yellow dispersion 7.4
Magenta dispersion 7.4
Cyan dispersion 7.4
Each color was coated on 3 mii polyester film (Meli-
nex O)~at a coating weight of 9.2 g/m2, dried for 2' at 60C,
and exposed for 1/3 unit for black and 1/2 unit for yellow, ma-
genta, and cyan.
Four color transfers were prepared, again, by apply-
ing Acryloid B-48 N adhesive to the Mark I~cover sheet as in
' ' ' ' - .
-32-
- : ..
-- : , , ~, .
' AZ-739
104587Z
Example II and carrying out the transfer as in Example I.
Complete image transfer was obtained with excellent
dot rendition.
Example XI
The following formulation was prepared and pigment-
ed as described in Example I: -
Methyl methacrylate/Methacrylic acid 56.0
copolymer a5/15 25% solution in ethyl
cellosolve
Poly~thylene glycol diacrylate (400) 10.0
2,3 dimethoxy phenyl quinoxaline 0.2
The pigmented systems were applied to 3 mil (Melin-
. ~
exO) polyester film and dried in a 60C air oven for 2'. A
; dry coating weight of 4,5 g/m2 was obtained.
The coatings were then covered with another sheet
o:Melinex 0 polyester film and exposed for 1/2 NuArc unit
through the carrier sheet. The cover sheet was removed and
attempts were made to transfer the unexposed images to bonded
printing paper by means of hot transferin the DuPont CTF
20 laminator.
The unexposed portions of the images could only be
partially transferred at 225F and at usual laminator press-
.. ~ ~
ures (15-20 psi).
~xample XII
The following photopolymerizable system, also based
on dyes, was prepared as indicated in Example VII.
(All quantities are in grams.)
,
'. ' ' '
~, . ' ' . .
. .. , .: . , . . : : :. .
AZ-73g
104S872 _~ y_
Component Cyan Yellow Magenta Black
Methacrylic acid/ 56.0 56.056.0 56.0
styrene/hexyl meth-
acrylate (28/22/50)
25% solids in MEK
Polyethylene glycol 3.75 3.75 3.75 2.80
diacrylate 400
Trimethylol Propane 1.25 1.25 1;25 .95
Triacrylate
9 Phenyl Acridine .6 .6 .6 1.25
Victoria Pure Blue .093
~FGA D~E (BASF)
Interplast Pink 5 BLG ~ .044
~I~tracolor)
Rhodamine 6 GDN-Extra .2
(DuPont)
Black Dispersion 15.4
~Example I)
Spirit Soluble Fast .51
Yellow "A" (BASF)
T~i methyl propane 3.75
Tri methacrylate
It was found most convenient to dissolve the dyes
in methyl cellosolve according to the followlng concentra-
tions:
Victoria Pure Blue Dye 1.5g/100 gms. M.C.
Spirit soluble Fast Yellow "A" 7.0g/100 gms. M.C.
Auramine 0 2.6gjlOO gms. M.C.
Interplast Pink 5 BLG ~ .6g/100 gms. M.C.
Rhodamine 6 GDN 4.2g/100 gms. M.C.
These solutions were filtered and added to the for-
mulation in the amounts shown. The formulations were then
coated on polyester film (I.C.I.'s Melinex O), at a coating
weight of about 9.2g/m2 and dried for 2' at 140C.
All four photosensitive coatings were exposed for
1/3 of a NuArc~unit through the appropriate negative placed
A~
. .. , . ~ .
. . .
- . .... ,: ~ .... . .. .. -
AZ-739
1(~4~87Z - 3 s
on the film support side of the coated carrier film.
An alkaline developer, EN-ll, sùpplied by Kalle AG
was used and images with step wedges of solid 4 ghosting to
7 were obtained.
A Mark I~cover sheet, as described in Example IV,
was coated with Acryloid B-48N adhesive (Rohm & Haas) to a
dry coating weight of about 20g/m2 and dried for 15 minutes
in a 60C hot air oven and then 2 hours in a 100C hot air
oven.
The developed images and receptor sheets were mated
and images transferred through the CTF laminator as in Exam-
ple I. Four color proofs were obtained with excellent dot
rendition.
It should be understood that, while the examples
refer to paper receptor sheets, plastic, plastic~paper la-
minates, metal foils and other combinations may also be
utilized. Particularly, suitable receptor sheets may be the
same types used as a carrier support, such as thin films of
polyethylene terephthalate, copolymers and terpolymers of
methyl methacrylate, modified celluloses, 6,6 Nylon, 6,12
Nylon, 6 Nylon, polyvinyl acetates and alcohols, etc.
It should a 190 be understood that the adhesive may
be applied to the imaged support sheet prior to transfer
; of the image areas to the receptor 9heet.
The adhesive may be applied to the imaged support
sheet by the transfer coating technique previously described.
. ~owever, other suitable methods of applying adhesive to the
imaged support sheet, or to the receptor sheet, prior to
` AZ-739
1~)4S87Z
transfer of the image areas to the receptor sheet may also
be practiced. Reference is made to U. S. Patent No.
3,721,557 which discloses a number of suitable techniques.
While the previous examples refer to photopolymer-
izable, light-hardenable coatings, negative-working systems,
with suitable resinous binders, negative-working diazo sen-
sitizors and appropriate dyestuffs and/or pigments, can be
used for the same purpose.
It will be obvious to those skilled in the art
that many modifications may be made within the scope of the
present invention without departing from the spirit thereof
and the invention includes all such modifications.
. -
- 3 ~ - :
' ~ .
. .
:
'' '
- . . - . . .
