A multilayer, photosensitive element comprising a coversheet, a photohardenable layer, a contiguous layer, an isolation layer, an adhesive layer, and a support, is described. The element is used for image reproduction.

FIELD OF THE INVENTION 
This invention relates to a multilayer, photosensitive element for image 
reproduction. More particularly, it relates to a photosensitive element 
comprising a coversheet, a photohardenable layer, a contiguous layer, an 
isolation layer, an adhesive layer, and a support. 
BACKGROUND OF THE INVENTION 
Photosensitive elements for image-reproduction are well-known in the 
graphics arts industry. Elements are exposed to actinic radiation through 
an image-bearing transparency, such as a color separation transparency, to 
produce an image that is either a positive or negative of the 
transparency. After imagewise exposure, the photosensitive elements are 
developed by washing out the soluble image areas, toning with a colorant, 
peeling apart, or combinations of these techniques. 
Peel-apart photosensitive elements, which do not require a solvent for 
their development, are disclosed in Cohen, U.S. Pat. Nos. 4,174,216 and 
4,247,619. These elements comprise, in order a strippable coversheet, a 
photoadherent photohardenable layer, a tonable contiguous layer, and a 
support. The element is imagewise exposed through the coversheet, and the 
coversheet is subsequently peeled off. The exposed areas of the 
photosensitive layer adhere to the coversheet and are removed, revealing 
the tonable contiguous layer. The unexposed areas of the photosensitive 
layer which remain on the contiguous layer do not accept toner. The 
revealed contiguous layer is toned in a succeeding step to produce a 
negative image of the transparency used for exposure. The toned image may 
be used as a single-color surprint proof. 
The process described above can be used to produce a multicolored image. 
First, the support is removed from a photosensitive element thereby 
revealing the contiguous layer. The contiguous layer of the resulting 
element is adhered to the exposed and peeled-apart photohardenable layer 
of a previously formed colored image. The resulting element is then 
imagewise exposed through the coversheet, peeled-apart, and toned with a 
different colored toner to produce a two-color image. This sequence of 
steps may be repeated as many times as desired to produce a multicolored 
surprint proof. 
The elements disclosed by Cohen have numerous advantages for the production 
of colored images. However, imperfections known as "pickoff defects" can 
occur during image formation. In addition, these elements may have a 
higher dot gain than the press print. A high dot gain is unsuitable in the 
printing industry. 
Pickoff defects occur when portions of the contiguous layer adhere to the 
exposed photohardenable layer and are removed with the photohardenable 
layer when the exposed element is peeled apart. Regions which should 
accept toner are not able to do so because the tonable contiguous layer 
has been removed. Also, in the production of multicolored images, the 
contiguous layer from an earlier formed colored image may be revealed and 
accept toner during the toning process. Consequently, pickoff defects have 
a deleterious effect on the image and may make it unsuitable for use as a 
prepress proof. 
The production and mounting of printing plates is expensive and time 
consuming. Thus, it is essential that a proof accurately predict the 
appearance and quality of the image obtained by printing. The dots on a 
halftone press print are larger than the dots on the corresponding 
halftone separation transparency. This phenomenon is known as dot gain. A 
discussion of dot gain and its causes can be found in Principles of Color 
Proofing, by Michael H. Bruno, GAMA Communications, Salem, NH, 1986, pp 
84-87. For a prepress proof to be an acceptable representation of the 
press print, it must accurately duplicate the dot gain of the press print. 
The elements described by Cohen generally produce too much dot gain and 
thus, the resulting proof does not completely simulate the press print. 
Precolored peel apart photosensitive elements, in which the photohardenable 
layer comprises a colorant, are disclosed in Taylor, U.S. Pat. No. 
4,489,154, and in Choi, U.S. Pat. No. 5,001,036. In certain instances, 
these elements have an advantage over tonable elements because it is 
unnecessary to apply a colorant to the element after it has been exposed 
and peeled apart. Although these elements have been used to produce 
overlay proofs, it has not been possible to use them to produce multicolor 
surprint proofs due to pickoff defects. 
Accordingly, a need exists for a photosensitive element which does not have 
pickoff defects and which more accurately duplicates the dot gain of the 
printing press. 
SUMMARY OF THE INVENTION 
In one embodiment, this invention concerns a multilayer, peel-apart, 
photosensitive element comprising, in order: 
(1) a strippable coversheet which is transparent to actinic radiation; 
(2) a photohardenable layer; 
(3) a contiguous layer; and 
(4) a support; 
wherein the adhesive relationship is such that, on peeling apart, either 
the unexposed or exposed regions of said photohardenable layer are removed 
with said coversheet while the other of said unexposed and exposed regions 
remain on said contiguous layer; 
the improvement wherein said photosensitive element additionally comprises: 
(5) a non-elastomeric isolation layer; and 
(6) an adhesive layer; 
wherein said isolation layer and said adhesive layer are arranged so that 
the photosensitive element comprises, in order from top to bottom, said 
coversheet, said photohardenable layer, said contiguous layer, said 
isolation layer, said adhesive layer, and said support. 
In a preferred embodiment of this invention, the photohardenable layer 
comprises a monomer, a binder, and a photoinitiator system activatible by 
actinic radiation. In another preferred embodiment, the unexposed regions 
of the photohardenable layer adhere more strongly to the contiguous layer 
and the exposed regions of the photohardenable layer adhere more strongly 
to the coversheet. In yet another preferred embodiment, the 
photohardenable layer additionally comprises a colorant and the support is 
removable. 
This invention also concerns improved processes for forming colored images 
using the multilayer, peel-apart, photosensitive elements of the 
invention. 
Few, if any, pickoff defects are produced when a photosensitive element of 
this invention is used to produce a colored image. The number of images 
unsuitable for use as surprint proofs is greatly reduced. Surprisingly and 
unexpectedly, dot gain is also reduced. The colored image closely 
simulates the image produced by printing.

DETAILED DESCRIPTION OF THE INVENTION 
In accordance with the invention, there is provided, a peel-apart 
photosensitive element adapted for the preparation of colored images. 
Referring to FIG. 1A, the photosensitive element (10) comprises, in order, 
a coversheet (12), a photohardenable layer (14), a contiguous layer (16), 
an isolation layer (18), an adhesive layer (20), and a support (22). 
In one preferred embodiment, the support (22) is removable. Referring to 
FIG. 1B, the support (22) has been removed and the element minus support 
(22) is adhered to a receptor (24). The adhesive relationship of the 
photohardenable layer (14) relative to the coversheet (12) and contiguous 
layer (16) is such that the unexposed regions (26) of the photohardenable 
layer (14) adhere more strongly to the contiguous layer (16) and the 
exposed regions (28) of the photohardenable layer (14) adhere more 
strongly to the coversheet (12) and are thus removed. If the element is 
not precolored, i.e., the photohardenable layer (14) does not comprise a 
colorant, the revealed regions (30) of the contiguous layer (16) are toned 
to produce a colored image which is a negative of the transparency used 
for exposure. Thus, the element is said to be "negative working". If the 
element is precolored, i.e., the photohardenable layer (14) comprises a 
colorant and therefore does not need to be subsequently toned, the 
unexposed regions (26) which remain on the contiguous layer (16) form a 
colored image which is a positive of the transparency used for exposure. 
Thus, the element is said to be "positive working" . 
In another preferred embodiment, the support (22) is removable, and the 
element (10) is precolored, and additionally comprises a photorelease 
layer between the coversheet and the photohardenable layer. Referring to 
FIG. 1C, the support (22) has been removed and the element minus the 
support (22) is adhered to a receptor (24). The adhesive relationship of 
the photohardenable layer (14) relative to the coversheet (12) and the 
contiguous layer (16) is altered by the photorelease layer (32) such that 
the exposed regions (34) of the photohardenable layer (14) adhere to the 
contiguous layer (16) and the unexposed regions (36) of the 
photohardenable layer (14) adhere more strongly to the photorelease layer 
(32) and the coversheet (12) and are removed. The exposed regions (34) of 
the photohardenable layer (14) which remain on the contiguous layer (16), 
produce a colored image which is a negative of the transparency used for 
exposure. Thus, the element is said to be "negative working". 
The terms "positive-working" and "negative-working" as used herein, refer 
to the relationship of the final image produced by the element to the 
transparency used for exposure, and not to the operation of the element. 
Positive-working elements produce a duplicate image of the transparency; 
that is, the colored regions of the transparency are colored and the 
uncolored regions in the transparency are uncolored in the final image. 
Negative-working elements produce an image that is the reverse of the 
transparency; that is, the colored regions of the transparency are 
uncolored and the uncolored regions in the transparency are colored in the 
final image. 
Non-precolored and precolored peel apart elements in which the exposed 
regions are removed with the coversheet on peeling apart, i.e., the 
element operates by photoadherence, will produce opposite images. Thus, in 
the non-precolored element, the exposed regions (28) of the 
photohardenable layer (14) are removed, revealing the contiguous layer 
(16) which is then toned. In the final image, the colored regions 
correspond to the exposed regions of the photohardenable layer (14) which, 
in turn, correspond to the uncolored regions of the transparency. Since 
the colored regions of the final image correspond to the uncolored regions 
in the transparency, a negative image is produced. 
In a precolored element, removal of the exposed regions (28) of the 
photohardenable layer (14) also leaves the unexposed regions (26) of the 
photohardenable layer (14) on the contiguous layer (16). However, since 
the unexposed regions (26) are precolored, in the final image, the colored 
regions of the image correspond to the colored regions of the transparency 
used for exposure. Thus, a positive image is produced. 
In elements in which the unexposed regions are removed on peeling apart, 
i.e., the element operates by photorelease, the opposite effect will be 
observed. Thus, a non-precolored element will, on peeling apart and 
toning, produce a positive image. On peeling apart, a precolored element 
will produce a negative image. 
The normal operation of a photoadherent element may be reversed, i.e., act 
as if it was not a photoadherent element, by the process disclosed in 
Taylor, U.S. Pat. No. 4,987,051. In this process the coversheet (12) is 
first removed, and the element is imagewise exposed. Following imagewise 
exposure, the coversheet (12) is replaced, and the element is overall 
exposed. The element is subsequently peeled apart. In this process, the 
exposed regions of the photohardenable layer (14) remain on the contiguous 
layer (16) and the unexposed regions are removed with the coversheet (12). 
The use of this process is considered to be equivalent to using a 
photorelease peel-apart photosensitive element. 
CONTIGUOUS LAYER/ADHESIVE LAYER 
The contiguous layer (16) is a tacky, or slightly soft, deformable material 
which is able to accept toner. To produce an element with good aging 
stability, suitable materials for the contiguous layer should resist 
monomer diffusion from the photohardenable layer into the contiguous 
layer. In addition, these materials should not migrate into the 
photohardenable layer. Preferred materials are elastomeric polymers and 
mixtures thereof, which are inherently tacky at ambient temperatures, such 
as, for example, natural or synthetic rubbers. Especially preferred 
materials are polymers of butadiene or isoprene and random, teleblock, 
block copolymers of butadiene or isoprene copolymerized with styrene, and 
poly(alpha-olefins) in which the alpha-olefin contains from about five to 
about ten carbon atoms. For nonprecolored tonable elements, the contiguous 
layer must be tonable, i.e., the toner must adhere to the contiguous 
layer. For precolored elements, it's not essential for the contiguous 
layer to be tonable. The contiguous layer may also contain oxidation 
inhibitors, optical brighteners, ultraviolet absorbers, antihalation 
agents, and the like. A preferred oxidation inhibitor is Irganox.RTM. 
1010, which is preferably present at a level of 0.1% to 1% by weight. 
The adhesive layer (20) adheres the element to the support (22) or to the 
exposed and peeled apart photohardenable layer of the previous element 
when the element is used to prepare a multicolor image. Preferred 
materials for the adhesive layer (20) are elastomeric polymers and 
mixtures thereof, which are inherently tacky at ambient temperatures, such 
as the polymers described above for the contiguous layer (16). The same 
material may be used in both the contiguous layer and the adhesive layer. 
Alternatively, different materials may be used. 
ISOLATION LAYER 
The isolation layer (18) comprises a film forming organic polymer which is 
less deformable than the polymers contained in the contiguous layer and 
the adhesive layer. The isolation layer must also possess good clarity and 
low color. In addition, it must adhere to the contiguous layer and to the 
adhesive layer. Various non-elastomeric organic polymers which can be used 
include (a) polymers and copolymers of vinyl acetate, such as, for 
example, poly(vinyl acetate) and ethylene/vinyl acetate copolymer; (b) 
acrylic and methacrylic polymers and copolymers, such as, for example, 
poly(methyl methacrylate), poly(ethyl methacrylate), poly(n-butyl 
methacrylate), poly(isobutyl methacrylate), and methyl methacrylate/butyl 
methacrylate copolymers; and (c) compatible mixtures thereof. A preferred 
polymer is poly(vinyl acetate). 
PHOTOHARDENABLE LAYER 
The photohardenable layer (14) is one whose adhesive relationship relative 
to the coversheet (12) and the contiguous layer (16) is such that, after 
exposure to actinic radiation, the unexposed or exposed regions of the 
photohardenable layer adhere more strongly to the coversheet while the 
other regions of the photohardenable layer adhere more strongly to the 
contiguous layer. Materials with ethylenically unsaturated groups which 
are photohardenable, photopolymerizable, photocrosslinkable, and/or 
photodimerizable, are used in the photohardenable layer, and are 
"photohardenable" within the meaning of this application. The preferred 
photohardenable compositions are photopolymerizable and comprise an 
organic polymeric binder, an addition polymerizable ethylenically 
unsaturated monomer, and an initiator system activatible by actinic 
radiation. AND 
In an element which operates by photoadherence, the element (10), is 
imagewise exposed and the exposed terephthalate of the photohardenable 
layer are removed with the coversheet when the element is peeled apart. 
Photoadherent peel-apart photosensitive elements are disclosed in Cohen, 
U.S. Pat. Nos. 4,174,216 and 4,247,619; and Taylor, U.S. Patent, U.S. Pat. 
No. 4,489,154. 
In an element which operates by photorelease, the element (10), is 
imagewise exposed and the unexposed regions of photohardenable layer are 
removed with the coversheet when the element is peeled apart. Photorelease 
photosensitive elements are disclosed in Cohen, U.S. Pat. No. 4,282,308; 
Choi, U.S. Pat. No. 5,001,036; and Applicant's assignee's U.S. patent 
application No. 07/542,470, filed on Jun. 22, 1990 and U.S. patent 
application No. 07/741,715 filed Aug. 7, 1991. 
MONOMERS/BINDERS 
The monomer has at least one and preferably two or more terminal 
ethylenically unsaturated groups capable of free-radical initiated, chain 
propagated, addition polymerization, and preferably has some degree of 
polarity. In addition, the monomer must be compatible with the binder and 
substantially nondiffusible in the contiguous layer. Useful monomers 
include epoxy monomers containing ethylenic unsaturation, such as those 
disclosed in Crary, U.S. Pat. No. 3,661,576. Preferred monomers are the 
diacrylate and dimethacrylate esters of the epichlorohydrin adduct of 
bis-phenol A. 
The binder can be a polar material, such as an acidic polymer containing at 
least 1.5 mole percent free acid groups to impart polarity to the polymer, 
or a nonpolar material such as the materials described in Burg, U.S. Pat. 
No. 3,060,023; Chu, U.S. Pat. No. 3,649,268; and Collier, U.S. Pat. No. 
3,984,244. Suitable binders include polymers of methyl acrylate, methyl 
methacrylate, and copolymers thereof. A preferred binder is poly(methyl 
methacrylate). 
PHOTOINITIATOR SYSTEM 
The photoinitiator system comprises one or more compounds which directly 
furnish free-radicals when activated by actinic radiation. It can also 
comprise a plurality of compounds, one of which yields free-radicals after 
having been caused to do so by another compound, or sensitizer, which has 
been activated by the radiation. 
Numerous conventional photoinitiator systems may be used provided they (a) 
are compatible with the other ingredients of the system, (b) do not alter 
the unique relationship between the coversheet; the contiguous layer; the 
photorelease layer, if present; and the exposed and unexposed 
photohardenable layer required for the operation of the element, and (c) 
do not impart unwanted color to the final image. 
Preferred photoinitiator systems are 2,4,5-triphenylimidazolyl dimers in 
combination with chain transfer agents, or hydrogen donors, such as are 
disclosed in Chambers, U.S. Pat. No. 3,479,185; Cescon, U.S. Pat. No. 
3,784,557; Dessauer, U.S. Pat. No. 4,311,783; and Sheets, U.S. Pat. No. 
4,622,286. Preferred hexaarylbisimidazoles (HABI) are 
2-o-chloro-substituted hexaphenylbisimidazoles in which the other 
positions on the phenyl radicals are unsubstituted or substituted with 
chloro, methyl or methoxy. The most preferred initiator is o-Cl-HABI, 
i.e., 1,1'-biimidazole, 2,2'-bis(o-chloro-phenyl)-4,4,'5,5'-tetraphenyl-. 
A preferred sensitizer is 7-diethylamino-4-methylcoumarin. 
Hydrogen donor compounds useful as chain transfer agents in the 
photopolymer compositions include: 2-mercaptobenzoxazole, 
2-mercaptobenzothiazole, 4-methyl-4H-1,2,4,triazole-3-thiol, and the like. 
A preferred hydrogen donor is 2-mercaptobenzoxazole. 
Although the HABI initiating systems described above are preferred, other 
initiating systems may be used in practicing this invention. Typical free 
radical-generating addition polymerization initiators include: quinones; 
ketones, such as Michler's ketone and benzophenone; dialkylamino 
benzaldehyde; benzaldehyde; dialkylamino benzoate esters; and combinations 
thereof. Other useful photoinitiators, described in U.S. Pat. No. 
2,760,863, include vicinal ketaldonyl alcohols, such as benzoin, pivaloin, 
acyloin ethers, e.g., benzoin methyl and ethyl ethers; 
alpha-hydrocarbon-substituted aromatic acyloins, such as 
alpha-methylbenzoin. 
Redox systems, such as those involving dyes, e.g., Rose 
Bengal/2-dibutylaminoethanol, may be also used. A useful discussion of dye 
sensitized photopolymerization can be found in "Dye Sensitized 
Photopolymerization" by D. F. Eaton in Adv. in Photochemistry, Vol. 13, D. 
H. Volman, G. S. Hammond, and K. Gollinick, eds., Wiley-Interscience, New 
York, 1986, pp. 427-487. For some applications such as color proofing, the 
use of dye-based initiator systems, especially those which use dyes whose 
absorption extends well into the visible region of the spectrum, may be 
undesirable because such dyes may affect the color of the resulting image. 
COLORANTS 
If the element is precolored, one or more colorants will be present in the 
photohardenable layer (14). Dyes and pigments may be used as colorants. 
Examples of suitable colorants include: 
yellow: Cromophtal.RTM. Yellow 3G (C.I. No. Pigment Yellow 93), 
Hostaperm.RTM. Yellow 3G (C.I. No. Pigment Yellow 154); 
magenta: Monastral.RTM. Violet R (C.I. No. Pigment Violet 19), 
2,9-Dimethylquinacridone (C.I. No. Pigment Red 122), Indofast.RTM. 
Brilliant Scarlet R6300 (C.I. No. Pigment Red 123), Quindo Magenta RV 
6803; 
cyan: Monastral.RTM. Blue G (C.I. No. Pigment Blue 15), Monastral.RTM. Blue 
(BT 383D) (C.I. No. Pigment Blue 15) Monastral.RTM. Blue G (BT 284D) (C.I. 
No. Pigment Blue 15), Monastral.RTM.Green GT (751D) (C.I. No. Pigment 
Green 7); 
black: Raven.RTM. 450 (C.I. No. Pigment Black 7), Raven.RTM. 1035 (C.I. No. 
Pigment Black 7), Elftex.RTM. 8 (C.I. No. Pigment Black 7), Elftex.RTM. 12 
(C.I. No. Pigment Black 7). 
Other colorants may be used provided that they (a) are compatible with the 
other ingredients of the system, and (b) do not alter the unique 
relationship between the coversheet, the contiguous layer, the 
photorelease layer, if present; and the exposed and unexposed 
photohardenable layer required for the operation of the element. 
OTHER INGREDIENTS 
The photohardenable layer (14) of both precolored and non-precolored 
photosensitive elements may also contain other ingredients which are 
conventional components of photohardenable systems provided they (a) are 
compatible with the other ingredients present in the photohardenable 
layer, (b) do not alter the unique relationship between the coversheet; 
the contiguous layer; the photorelease layer, if present; and the exposed 
and unexposed photohardenable layer required for the operation of the 
element, and (c) do not impart unwanted color to the final image. Such 
components may include stabilizers, antihalation agents, optical 
brightening agents, release agents, surfactants, coating aids, 
plasticizers, fillers, and the like. 
For non-precolored, tonable elements, about 3-15% of triacetin and 
preferably about 5-7%, may be added to the photohardenable layer (14) to 
prevent fine toned line defects. These defects appear as very fine lines 
of color in regions of the image which should be uncolored. Triacetin may 
also be added to the photohardenable layer of precolored photosensitive 
elements as disclosed in Peiffer, U.S. Pat. No. 5,087,549. 
A conventional thermal polymerization inhibitor is normally present to 
increase the storage stability of the element. The dinitroso dimers 
described in Pazos, U.S. Pat. No. 4,168,982, may also be useful. However, 
it is frequently unnecessary to add additional inhibitor because monomers 
generally contain polymerization inhibitors added by their manufacturers. 
Nonionic surfactants may be added to the photohardenable layer as coating 
aids. Preferred coating aids are polyethylene oxide, such as Polyox.RTM. 
WSRN 3000, and fluorinated nonionic surfactants, such as Fluorad.RTM. 
FC-430. 
The addition of optical brightening agents to the photohardenable layer 
produces an image which is free from distortion due to halation. Useful 
ultraviolet radiation absorbing materials and brighteners are disclosed in 
Held, U.S. Pat. No. 3,854,950. Particularly useful optical brighteners are 
2-(stibyl-4")-(naphto-1',2',4,5)-1,2,3-triazol-2"-sulfonic acid phenyl 
ester and 7-(4'-chloro-6'-diethylamino-1',3',5'-triazine-4'-yl) 
amino-3-phenyl coumarin. 
COMPOSITION 
The binder must be present in sufficient amount to form a film when the 
composition is coated. The monomer must be present in sufficient amount to 
alter the relative adhesive relationship so that, on peeling apart, either 
the unexposed or exposed regions of the photohardenable layer are removed 
with the coversheet while the other regions remain on the contiguous 
layer. The photoinitiator system must be present in sufficient amount to 
initiate polymerization of the monomer on exposure to actinic radiation. 
In precolored systems, the colorant must be present in a sufficient amount 
to uniformly color the image to a sufficient optical density, but not to 
the extent that it adversely affects the properties of the photohardenable 
layer, such as photospeed, adhesion, etc., needed for the operation of the 
element. Optical densities between 1 and 2 are desirable for surprint 
proofs. 
The binder/monomer ratio may vary widely but in general should be about 3:1 
to 1:3. The monomer should be compatible with, and may be a solvent for, 
and/or have a plasticizing action on the binder. The proportions of 
monomer and binder are made in accordance with the requirements of 
selective photoadhesion or photorelease and of hardness. To provide a 
suitable hardness, the monomer concentration is normally kept low so that 
the photohardenable layer will be sufficiently hard and non-tacky. 
For non-precolored, tonable elements, the composition of the 
photohardenable layer will typically be within the following percentage 
ranges, based on total weight of the photohardenable layer: about 5-60% 
monomer, preferably about 35-50%; about 0.1-10% initiator system, 
preferably about 1-5%; about 25-75% binder, preferably about 35-50%; and 
about 0-15% other ingredients, preferably about 3-10%. 
For precolored elements, in which the photohardenable layer comprises a 
colorant, the composition will normally contain, based on total weight of 
the photohardenable layer about 5-60% monomer, preferably about 35-50%; 
about 0.1-10% initiator system, preferably about 1-5%; about 20-70% 
binder, preferably about 30-45%; 0.5-20% colorant(s), preferably 8-15%; 
and about 0-15% other ingredients, preferably about 3-10%. 
SUPPORT/COVERSHEET/RECEPTOR 
The support (22) may be any suitable film which has the necessary stiffness 
and dimensional stability and which exhibits proper adhesion to the 
adhesive layer. A preferred material is polyethylene terephthalate film. A 
removable support is required for the preparation of a multicolor surprint 
proof. A silicon release treated polyethylene terephthalate film is 
preferred for this application. The support is typically about 25 to about 
125 microns thick. 
The coversheet (12) is strippable, i.e., removable by peeling it apart from 
the rest of the element. The adhesive relationship of the coversheet to 
the photohardenable layer will vary depending on whether the element 
operates by photoadherence or photorelease. For elements which operate by 
photoadhesion, the exposed regions of the photohardenable layer adhere 
more strongly to the coversheet while the unexposed regions adhere more 
strongly to the contiguous layer. For elements which operate by 
photorelease, the unexposed regions of the photohardenable layer adhere 
more strongly to the coversheet while the exposed regions adhere more 
strongly to the contiguous layer. 
The coversheet (12) must be transparent to actinic radiation because 
irradiation is carried out through the coversheet. The topography of the 
coversheet may be altered, and its polarity increased, by electrostatic 
discharge treatment as disclosed by Buzzell, U.S. Pat. No. 4,356,253 or by 
flame treatment with an air-propane flame. This will enable the exposed 
areas of the photohardenable layer to adhere better to the surface of the 
coversheet. Preferred materials for the coversheet are polymeric films, 
particularly polyethylene terephthalate film. For elements which operate 
by photoadhesion, the most preferred material is an electric discharge 
treated polyethylene terephthalate film. For elements which operate by 
photorelease and which additionally comprise a photorelease layer, the 
most preferred material is untreated polyethylene terephthalate film. 
While the thickness of the coversheet may vary over a wide range, films 
having a thickness of about 13-50 microns are preferred. Although thinner 
coversheets produce halftone dots of good roundness with sharp edges, the 
coversheet should be thick enough to prevent tearing when it is stripped 
from the element. If the coversheet is to be flame or electric discharge 
treated, it should be thick enough to prevent such treatment from injuring 
the coversheet. In general, a rapid rate of coversheet stripping produces 
better image quality. 
The receptor (24) may be any material which has the necessary stiffness and 
dimensional stability. The receptor is flat and preferably smooth and 
opaque. Exemplary materials which may be used as the receptor include 
adhesive subbed opaque polyethylene terephthalate film base, e.g., 
Melinex.RTM. 994 (ICI Americas Inc., Wilmington, Del.); and paper stock, 
e.g., Kromekote.RTM. opaque white paper (Champion Paper Co., Stamford, 
Conn.), or Cromalin.RTM. receptor stock (E. I. du Pont de Nemours and 
Company, Wilmington, Del.). The preferred material is an opaque white 
paper. 
PHOTORELEASE LAYER 
Photosensitive elements which operate by photorelease may comprise 
photohardenable compositions which photorelease, such as those described 
by Cohen, U.S. Pat. No. 4,282,308, and those described in U.S. patent 
application No. 07/542,470, filed on Jun. 22, 1990. Alternatively, 
photosensitive elements that operate by photorelease may comprise a 
photorelease layer (32) situated between the coversheet (12) and the 
photohardenable layer (14). The photorelease layer modifies the adhesive 
relationship between the coversheet and the photohardenable layer so that 
after the photohardenable layer has been exposed to actinic radiation, the 
unexposed, i.e., unphotohardened regions of the photohardenable layer, 
adhere more strongly to the coversheet than to the contiguous layer and 
are removed with the coversheet. The exposed, i.e., photohardened, regions 
of the photohardenable layer adhere more strongly to the contiguous layer 
than to the coversheet and remain on the contiguous layer when the element 
is peeled apart. 
Agents suitable for use in photorelease layers are disclosed in Choi, U.S. 
Pat. No. 5,001,036. These photorelease agents are solid, polymeric 
compounds which consist essentially of the oxyethylene repeat unit, i.e.: 
EQU --[OCH.sub.2 CH.sub.2 ]-- 
Various end groups, such as hydroxyl or alkoxyl, may be present. While 
small amounts of co-monomers (up to about 5%) may be present in the 
polyoxyethylene chain, provided the polymer is still solid at room 
temperature, oxyethylene homopolymers are preferred. 
Oxyethylene homopolymers are generally divided, on the basis of molecular 
weight into two groups. Those two groups are (a) polyethylene glycols and 
(b) polyethylene oxides. Both groups, however, are oxyethylene 
homopolymers with primary hydroxyl end groups, i.e., H(OCH.sub.2 
CH.sub.2).sub.n OH. 
The polyethylene glycols are a series of low to medium weight homopolymers 
of ethylene oxide. They can be regarded chemically as polyether diols 
consisting of long, linear chains of oxyethylene units with primary 
hydroxyl groups at each end. Depending on chain length, they range in 
physical form at room temperature from viscous liquids (MW 200-700), to 
waxy semisolids (MW 100-2000), to hard, waxlike solids (MW 3,000 to 20,000 
and above). 
The polyethylene oxides are a series of high molecular weight oxyethylene 
homopolymers. They are free-flowing white powders commercially available 
in a broad range of molecular weight grades, i.e., as low as 100,000 to as 
high as 5,000,000. Polyethylene oxides are available from the Union 
Carbide Corporation under the tradename Polyox.RTM.. Oxyethylene polymers 
are discussed in detail in Chapters 18 and 19 of Handbook of Water-Soluble 
Gums and Resins, R. L. Davidson, Ed., McGraw-Hill, New York, 1980. 
The photorelease agent is typically coated onto the coversheet. Thus, the 
polymer used as a photorelease agent, must be of sufficient molecular 
weight to be a solid at ambient temperature. The polymer must also form a 
film at ambient temperature. Although polyethylene oxides with varying 
molecular weights can be used, oxyethylene homopolymers with a molecular 
weight greater than 20,000 are preferred. More preferred are oxyethylene 
homopolymers in the molecular weight range of about 100,000 to about 
600,000. The most preferred photorelease agents have a molecular weight of 
about 300,000 to 400,000. 
The photorelease layer consists essentially of the photorelease agent, but 
it may also contain minor amounts of other ingredients that do not 
materially affect its essential characteristic, i.e, photorelease. 
Preferably the photorelease layer will contain at least 65%, and more 
preferably, at least 75% of a photorelease agent. 
Other ingredients can be added to the photorelease layer to improve 
performance. For example, a surfactant may be added as a coating aid. 
Preferred coating aids for the photorelease layer are low molecular 
weight, non-ionic polyethylene oxide/polypropylene oxide/polyethylene 
oxide copolymers. The coating aid may be added at 0=14 1% (weight/volume) 
of the coating solution, preferably at about 0.1% (weight/volume) of the 
coating solution. 
The addition of poly(vinyl pyrrolidone) (PVP) to the photorelease layer 
improves image quality by providing a cleaner separation of the coversheet 
when the element is peeled apart. A preferred PVP is PVP K-90, a high 
molecular weight PVP. PVP may be added as 0-5% of the photorelease 
Poly(acrylic acid) improves aging performance and reduces peel sensitivity, 
that is, the sensitivity of the quality of the image to the rate and 
smoothness of the peeling apart of the element. Poly(acrylic acid) may be 
added at about 0-10% of the photorelease layer, and preferably about 
4-10%. 
MANUFACTURE 
The photohardenable layer (14) is prepared by (a) mixing the ingredients of 
the system in a suitable solvent, such as dichloromethane, usually in the 
weight ratio of about 15:85 to 25:75 (solids to solvent), (b) coating the 
photohardenable layer onto a coversheet (12), and (c) evaporating the 
solvent. The coating should be uniform. The coating weight is typically 
about 15-40 mg/dm.sup.2, and preferably about 20-30 mg/dm.sup.2. 
Any suitable solvent may be used to coat the contiguous layer (16), 
isolation layer (18), and adhesive layer (20). The coatings should be 
uniform. The contiguous layer typically has a dry coating weight of about 
5 to 120 mg/dm.sup.2, preferably 10 to 80 mg/dm.sup.2. The isolation layer 
typically has a dry coating weight of 20 to 100 mg/dm.sup.2. The adhesive 
layer typically has a dry coating weight of 15 to 70 mg/dm.sup.2. 
The photorelease layer (32) may be coated onto the coversheet (12) from 
water or any other solvent or solvent mixture in which it is soluble. Good 
image reproduction requires formation of a discrete, uniform, contiguous 
film. The photorelease layer may be 0.03 to 0.3 micron thick, preferably 
0.05 to 0.2 micron, and more preferably, about 0.1 to 0.15 micron thick. 
The photosensitive element (10) may be prepared using conventional coating 
techniques. If the photorelease layer is not present, the photohardenable 
layer is coated onto the coversheet. After the solvent has evaporated, a 
release film, such as polyethylene, may be placed over the coating to 
protect the photohardenable layer until the rest of the element is formed. 
The contiguous layer is then coated over the photohardenable layer. If a 
release film is present on the photohardenable layer, it must be stripped 
off before the contiguous layer is coated. The adhesive layer is coated 
onto the support. Following evaporation of the solvent, the isolation 
layer is coated onto the adhesive layer. After the solvent has evaporated, 
the surface of the isolation layer is laminated to the surface of the 
contiguous layer. 
The photosensitive element (10) may also be prepared using conventional 
multilayer coating techniques. For example, the photohardenable layer and 
the contiguous layer may be coated simultaneously onto the coversheet. 
Similarly, the adhesive layer and the isolation layer may be coated 
simultaneously onto the support. The surface of the isolation layer is 
then laminated to the surface of the contiguous layer. 
If the photorelease layer is present, it is first coated onto the 
coversheet. The element is then formed as described above. Other ways of 
preparing the photosensitive elements of this invention will be apparent 
to those skilled in the art. 
EXPOSURE 
Any convenient source may be selected to provide actinic radiation absorbed 
by the photoinitiator system. The radiation can be natural or artificial, 
monochromatic or polychromatic, incoherent or coherent. Most of the 
actinic radiation should be absorbed by the photoinitiator system to 
provide efficient image formation. Conventional sources of actinic 
radiation include fluorescent, mercury vapor, mercury-xenon, metal 
additive, and arc lamps. Useful sources of coherent radiation are lasers 
whose emissions fall within or overlap the absorption bands of the 
photoinitiator system. Exposure is conventionally carried out through an 
image-bearing transparency, preferably a halftone or continuous tone color 
separation transparency. However, other means, such as a modulated 
scanning laser beam, cathode ray tube, and the like, can be used to 
imagewise expose the element. These alternative methods of exposing the 
element are considered to be equivalent to exposure through an 
image-bearing transparency. 
IMAGE FORMATION: NON-PRECOLORED ELEMENTS 
Following exposure and peeling-apart of a non-precolored element, the 
element is colored by applying a suitable colorant, generally know as a 
toner. The excess toner is removed, and toner remains only on the revealed 
regions (30) of the contiguous layer (16), i.e., the regions of the 
contiguous layer (16) from which the exposed regions (28) of the 
photohardenable layer (14) were removed. Suitable toners are described in 
Chu, U.S. Pat. No. 3,620,726; Gray, U.S. Pat. No. 3,909,282; Manger, U.S. 
Pat. No. 4,215,193; and Ruskin, U.S. Pat. No. 4,661,439. Toners may be 
applied by dusting with pads dipped in toners as disclosed in Burg, U.S. 
Pat. No. 3,060,024; hand-operated machine toning as disclosed in Sandner, 
U.S. Pat. No. 4,019,821; and automatic toning as disclosed in Tobias, U.S. 
Pat. No. 4,069,791. Colorant applied by a transfer process described in 
Burg, U.S. Pat. No. 3,060,025 using a precolored toning film, such as 
described in Frohlich, U.S. Pat. No. 4,806,451, is considered to be toning 
within the scope of this application. 
A non-precolored photosensitive element with a removable support is used to 
prepare multicolor surprint proofs from conventional negative halftone 
color separation transparencies. First, the support is removed from the 
photosensitive element; and the element minus the removable support is 
then adhered to a permanent support known as the receptor. The resulting 
composite structure is then exposed to actinic radiation through the 
coversheet using a color separation transparency or by an equivalent 
exposure process. The coversheet is subsequently peeled off the exposed 
element at room temperature or at an elevated temperature by stripping 
with a smooth, moderate to rapid, continuous motion, preferably at a peel 
angle of 180.degree.. The revealed contiguous layer is then colored by 
applying a toner of a color corresponding to the color separation 
transparency used in the exposure step. 
A multicolor surprint proof is prepared, by adhering an additional 
photosensitive element, minus its removable support, to the exposed, 
peeled apart photohardenable layer of the image previously prepared. The 
resulting element is exposed in register through a different color 
separation transparency, peeled apart, and toned as described above to 
produce a two color image. This sequence of steps may be repeated as many 
times as desired to produce a multicolor proof. A typical surprint proof 
comprises yellow, magenta, cyan, and black images. A topcoat, such as that 
described in Taylor, U.S. Pat. No. 4,921,776, may be applied to the 
surprint proof as a final protective layer. 
IMAGE FORMATION: PRECOLORED ELEMENTS 
Following exposure and peeling-apart of a precolored element, a one-color 
precolored image is produced. A precolored image, as used herein, refers 
to an image produced from a precolored element, i.e., an element 
comprising a colorant. 
A precolored photosensitive element with a removable support is used to 
prepare surprint proofs from conventional halftone color separation 
transparencies. The support is removed from the photosensitive element and 
the element minus the removable support is then adhered to a permanent 
support known as the receptor. The resulting composite structure is 
exposed to actinic radiation through the coversheet using a color 
separation transparency or by an equivalent exposure process. If exposure 
is through a negative color separation transparency, an element which 
operates by photorelease should be used. If exposure is through a positive 
separation transparency, an element which operates by photoadherence 
should be used. The coversheet is then peeled off the exposed element as 
described above, to produce a single-color surprint proof. 
A multicolor surprint proof is prepared by adhering an additional 
photosensitive element, minus its removable support, to the exposed, 
peeled apart photohardenable layer of the image previously prepared. The 
resulting element is exposed in register through a different color 
separation transparency and peeled apart as described above to produce a 
two-color image. This sequence of steps may be repeated as many times as 
desired to produce a multicolor proof. A topcoat, such as that described 
in Taylor, U.S. Pat. No. 4,921,776, may be applied to the surprint proof 
as a final protective layer. 
Multicolor images may also be prepared by combining precolored and 
non-precolored photosensitive elements. For example, a four color surprint 
proof may be prepared from the precolored elements by the process 
described above. A fifth color is then added by removing the support from 
a non-precolored element and the element, minus the removable support, is 
laminated to the precolored image. The element is then exposed in 
register, peeled apart, and toned as described above to produce a five 
color proof which is made up of four precolored elements and one 
non-precolored element. Alternatively, a non-precolored element may 
replace one of the precolored elements in a four color proof. The 
precolored elements may also be combined with the non-precolored elements 
disclosed in Chu, U.S. Pat. Nos. 3,620,726 and 3,649,268. Other possible 
combinations of precolored and non-precolored elements will be apparent to 
those skilled in the art. Thus, the combination of precolored and 
non-precolored photosensitive elements permits the preparation of surprint 
proofs containing standard colors, i.e., colors which are supplied in 
precolored element, and specialty colors, i.e., colors which are not 
supplied in precolored elements. 
INDUSTRIAL APPLICABILITY 
The elements of this invention are useful for preparing colored images. 
These images are particularly useful in the graphic arts field, especially 
for color proofing in which proofs are prepared to duplicate the images 
produced by printing. 
The advantageous properties of this invention can be observed by reference 
to the following examples which illustrate, but do not limit, the 
invention. 
EXAMPLES 
In the Examples which follow, "coating solution" refers to the mixture of 
solvents and additives coated on the coversheet, even though some of the 
additives may be in suspension rather than in solution. "Total solids" 
refers to the total amount of nonvolatile material in the coating solution 
even though some of the additives may be nonvolatile liquids at ambient 
temperature. 
______________________________________ 
GLOSSARY 
______________________________________ 
Calcofluor .RTM. White 
7-Diethylamino-4-methylcoumarin; 2H-1- 
benzo-pyran-2-one, 7-(diethylamino)-; 
CAS 71173-56-3; American Cyanamid, 
Wayne, NJ 
Carboset .RTM. 525 
Poly(ethyl acrylate/methyl 
methacrylate/acrylic acid) 56/37/7; 
B. F. Goodrich Co., Cleveland, OH 
-o-Cl-HABI 1,1'-Biimidazole, 2,2'-bis[ -o- 
chlorophenyl]-4,4',5,5'-tetraphenyl-; 
CAS 1707-68-2 
Cyan pigment 
Monastral .RTM. Blue G (BT 284D); C.I. 
Pigment Blue 15; copper phthalocyanine 
Diene 55AC Poly(cis-butadiene); Firestone, Akron, 
OH 
Elvacite .RTM. 2014 
Methyl methacrylate copolymer; E. I. 
du Pont de Nemours and Company, 
Wilmington, DE 
Elvacite .RTM. 2016 
Methyl methacrylate/n-butyl 
methacrylate copolymer; E. I. du Pont 
de Nemours and Company, Wilmington, DE 
Elvacite .RTM. 2042 
Poly(ethyl methacrylate); CAS 9093-42-3; 
E. I. du Pont de Nemours and Company, 
Wilmington, DE 
Elvacite .RTM. 2044 
Poly(n-butyl methacrylate); CAS 9003-63-8; 
E. I. du Pont de Nemours and Company, 
Wilmington, DE 
Elvacite .RTM. 2045 
Poly(iso-butyl methacrylate); 
CAS 9011-15-8; E. I. du Pont 
de Nemours and Company, Wilmington, DE 
Elvacite .RTM. 2051 
Poly(methyl methacrylate); MW 350,000; 
E. I. du Pont de Nemours and Company, 
Wilmington, DE 
Elvax .RTM. 140 
Ethylene vinyl acetate copolymer; 
E. I. du Pont de Nemours and Company, 
Wilmington, DE 
Ebecryl .RTM. 3704 
Acrylated esters of epoxy resins; 
Hoechst-Celanese, Summit, NJ 
FC-430 Fluorad .RTM. FC-430; fluoroaliphatic 
polymeric esters; CAS 11114-17-3; 3M, 
St. Paul, MN 
Gentro .RTM. 1506/27 
Styrene-butadiene random copolymeric 
rubber; Gen Corp., Akron, OH 
Goodrite .RTM. K-732 
Aqueous polyacrylic acid solution, 
partial sodium salt; B. F. Goodrich, 
Cleveland, OH 
Hetron .RTM. Q6332 
Unsaturated polyester resin; Ashland 
Chemical Co., Columbus, OH 
Irganox .RTM. 1010 
Tetra-bis-methylene-3-(3,5-di-tert- 
butyl-4-hydroxyphenyl) propionate 
methane; Ciba-Geigy, Hawthorne, NY 
Magenta pigment 
Quindo Magenta RV 6803; Harmon 
2-MBO 2-Mercaptobenzoxazole; 2- 
benzoxazolethiol; CAS 2382-96-9 
Methacrylate 
Elveron .RTM. 6037; Poly(methyl- 
dispersant methacrylate/2-ethylhexyl acrylate - 
Desmodur .RTM. N adduct; Mn 9,000 
Pluronic .RTM. L-92 
Liquid (ethylene oxide/propylene 
oxide/ethylene oxide) A-B-A block 
copolymer; BASF, Parsippany, NJ 
Polyox .RTM. WSRN 
Polyethylene oxide; MW 400,000; Union 
3000 Carbide, Danbury, CT 
PVP K-90 Polyvinylpyrrolidone (MW 350,000); 
GAF Corp., Wayne, NJ 
Raven .RTM. 450 
Carbon black, C.I. Pigment Black 7; 
Cities Service Co. 
Raven .RTM. 1035 
Carbon black, C.I. Pigment Black 7; 
Cities Service Co. 
Scarlet Pigment 
Indofast .RTM. Brilliant Scarlet R6300; 
C. I. Pigment Red 123 
Taktene .RTM. CB221 
Poly (cis-butadiene); Polysar, Akron, 
OH 
Tinopal .RTM. PCR 
2-(Stilbyl)-(naphtho-1',2',4,5)-1,2,3- 
trizol-2"-sulfonic acid phenyl ester; 
CAS 6994-51-0; Ciba-Geigy, Ardsley, NY 
Tinopal .RTM. SFG 
3-Phenyl-7-[2'-(4'-N,N-diethylamino)- 
6'-chloro-1',3',5'-triazinylamino]- 
coumarin; Ciba-Geigy, Hawthorne, NY 
Tinuvin .RTM. 328 
2-(2'-Hydroxy-3',5'-di-tert- 
amylphenyl)-benzotriazole; Ciba-Geigy, 
Hawthorne, NY 
Triacetin Glyceryl triacetate; Haarman & Reimer 
Corp., Springfield, NJ 
Uvitex .RTM. OB 
Benzoxazole, 2,2'-(2,5- 
thiophenediyl)bis[5-(1,1- 
dimethylethyl)]; CAS 7128-64-5 
Vinac .RTM. B-15 
Poly(vinyl acetate); MW 90,000; 
CAS 9003-20-7; Air Products and 
Chemicals, Allentown, PA 
Yellow Pigment 
Cromophtal .RTM. Yellow 3G; C.I. Pigment 
Yellow 93; Ciba-Geigy, Hawthorne, NY 
Zonyl .RTM. FSN 
Nonionic fluorosurfactant; E. I. 
du Pont de Nemours and Company, 
Wilmington, DE 
______________________________________ 
Control Example A and Examples 14 8 compare the number of pickoff defects 
and the effective dot area obtained using the photosensitive elements of 
this invention with the number of pickoff defects and the effective dot 
area obtained using elements which do not comprise the isolation and 
adhesive layers. 
EXAMPLES 1-8 
These examples illustrate the preparation and exposure of photosensitive 
elements of this invention. 
Step 1 
Photohardenable Layer (14) 
The composition described in Table 1 was coated onto about 12.2 micron 
thick clear polyethylene terephthalate coversheet, which had been surface 
treated by electrostatic discharge at about 0.05 coulomb/ft.sup.2 (0.544 
coulomb/m.sup.2), using conventional coating techniques. Coating 
conditions were 22.5% solids in dichloromethane at a coating weight of 
about 30 mg/dm.sup.2. Following coating, a polyethylene release film was 
placed on top of the photohardenable layer to protect it until the rest of 
the element was formed. An element consisting of coversheet, 
photohardenable layer, and release film was formed. 
TABLE 1 
______________________________________ 
Composition of the Photohardenable Layer.sup.a 
______________________________________ 
Elvacite .RTM. 2051 
43.51 
Ebecryl .RTM. 3704 
44.79 
Triacetin 5.00 
-o-Cl HABI 2.50 
2-MBO 1.50 
Tinopal .RTM. SFG 2.00 
Tinuvin .RTM. 328 0.20 
Polyox .RTM. WSRN 3000 
0.50 
______________________________________ 
.sup.a percent by weight 
Step 2 
Adhesive Layer (20) 
A coating solution of 89.78% Diene 55AC, 9.97% Gentro.RTM. 1506/27, and 
0.25% Irganox.RTM.1010 (5.5% solution in dichloromethane) was prepared. 
Step 3 
contiguous Layer (16) 
A coating solution of 79.5% Taktene.RTM.221, 20.0% Gentro.RTM. 1506, and 
0.5% of Irganox.RTM. 1010 (7.7% solids in dichloromethane) was prepared. 
Step 4 
Isolation Layer (18) 
A coating solution of Vinac.RTM. B-15 (22.5% solids in dichloromethane) was 
prepared. 
Step 5 
Photosensitive Element (10) 
The coating solutions for the contiguous layer and the isolation layer were 
coated simultaneously onto about 0.92 mil (about 23 micron) thick silicon 
treated polyethylene terephthalate film by a conventional multilayer 
coating technique to form an element consisting of polyethylene 
terephthalate film, isolation layer, and contiguous layer. The release 
film was removed from the element formed in Step 1, and the 
photohardenable layer was pressure laminated at room temperature to the 
contiguous layer to form an element consisting of: coversheet, 
photohardenable layer, contiguous layer, isolation layer, and polyethylene 
terephthalate film. The solution prepared in Step 2 was coated onto a 
support of about 0.92 mil (about 23 micron) thick silicon treated 
polyethylene terephthalate film to form an element consisting of adhesive 
layer and support. 
The polyethylene terephthalate film was removed from the element consisting 
of coversheet, photohardenable layer, contiguous layer, isolation layer, 
and polyethylene terephthalate film and the resulting element was pressure 
laminated at room temperature to the element consisting of adhesive layer 
and support to form photosensitive element (10) consisting of coversheet 
(12), photohardenable layer (14), contiguous layer (16), isolation layer 
(18), adhesive layer (20), and support (22). Coating weights for the 
photohardenable layer, contiguous layer, isolation layer, and adhesive 
layer are provided in Table 2. 
Step 6 
Image Formation 
The support was removed from the photosensitive element and the revealed 
adhesive layer laminated to Du Pont Cromalin.RTM. CRS/3 receptor stock (E. 
I. du Pont de Nemours and Company, Wilmington, Del.) to form an element 
consisting of receptor, adhesive layer, isolation layer, contiguous layer, 
photohardenable layer, and coversheet. This element was placed in a vacuum 
frame with the coversheet up, i.e., facing the light source. A test form 
consisting of an UGRA target (copyright 1982) and a field of 50 1.5 in 
(3.8 cm) diameter circles was placed on top of the coversheet with the 
emulsion side in contact with the coversheet. A vacuum was drawn on the 
element and transparency for 90 sec prior to exposure. The element was 
exposed for about 36 sec with the radiation from a 5 kw high pressure 
mercury vapor lamp (Violux.RTM. 5002S, Exposure Systems Company, 
Bridgeport, Conn.) equipped with a photopolymer bulb with a Kokomo.RTM. 
filter about 54 in (137 cm) above the element and transparency. 
The exposed element was removed from the vacuum frame and placed on a 
heated (about 26.degree. C.) peel table. The coversheet was removed by 
peeling back at 180.degree. ("peel-back mode") in a smooth, continuous 
motion. The revealed portions of the contiguous layer were toned with Du 
Pont negative Cromalin.RTM. black toner using a Du Pont Automatic Toning 
Machine (E. I. du Pont de Nemours and Company, Wilmington, Del.) to 
produce a black, one-color image consisting of receptor, adhesive layer, 
isolation layer, black toned contiguous layer, and exposed and 
peeled-apart photohardenable layer. 
The support was removed from a second photosensitive element and the 
revealed adhesive layer laminated to the one color image to form an 
element consisting of receptor, adhesive layer, isolation layer, black 
toned contiguous layer, exposed and peeled-apart photohardenable layer, 
adhesive layer, isolation layer, contiguous layer, photohardenable layer 
and coversheet. The element was exposed through the UGRA target and field 
of 50 1.5 in (3.8 cm) diameter circles as previously described. The UGRA 
target was placed in over an untoned region of the image. The circles 
overlapped, but were not in register with, those of the black image. The 
element was peeled apart and toned with cyan toner as previously described 
to form a two color image consisting of receptor, adhesive layer, 
isolation layer, black toned contiguous layer, exposed and peeled-apart 
photohardenable layer, adhesive layer, isolation layer, cyan toned 
contiguous layer, and exposed and peeled-apart photohardenable layer. 
This process was repeated, first with magenta toner and then with yellow 
toner, to produce a four-color image consisting of: receptor, adhesive 
layer, isolation layer, black toned contiguous layer, exposed and 
peeled-apart photohardenable layer, adhesive layer, isolation layer, cyan 
toned contiguous layer, exposed and peeled-apart photohardenable layer, 
adhesive layer, isolation layer, magenta toned contiguous layer, exposed 
and peeled-apart photohardenable layer, adhesive layer, isolation layer, 
yellow toned contiguous layer, and exposed and peeled-apart 
photohardenable layer. The image was protected by a layer of conventional 
Cromalin.RTM. off-press proofing system topcoat. 
Step 7 
Effective Dot Area 
Effective dot area (EDA) was measured for the cyan and magenta portions of 
the 30% and 50% regions of the UGRA test targets using a MacBeth RD 918 
reflection densitometer which measures the amount of light reflected by a 
solid image. The instrument contains a series of filters so that each 
image may be illuminated with light appropriate for the colored image 
being evaluated. (The cyan image is illuminated with red light, etc.) To 
calculate the effective dot area the amount of light reflected by a 
particular region is compared with the amount of light reflected by the 
receptor and the amount of light reflected by a region with 100% toner 
coverage. Effective dot areas are provided in Table 3. 
Step 8 
Pickoff Defects 
The 50 circles for each color and their overlapping regions were inspected 
for areas in which portions of the toned contiguous layer was missing. The 
number of locations in which the toned contiguous layer was missing was 
the number of pickoff defects. The number of pickoff defects is provided 
in Table 3. 
CONTROL EXAMPLE A 
Control Example A is a commercial multilayer, peel-apart, tonable 
photosensitive element (Cromalin.RTM. C/N negative off-press proofing 
film, E. I. du Pont de Nemours and Company, Wilmington, Del.) and 
represents the state of the art. Coating weights are given in Table 2. The 
element was exposed and toned as described in Step 6 of Example 1 to 
produce a four-color image. The number of pickoff defects and the 
effective dot areas for the cyan and magenta images at 30% dots and 50% 
dots using an UGRA target with 150 lines/in (60 lines/cm) are provided in 
Table 3. 
TABLE 2 
______________________________________ 
Coating Weight.sup.a 
Photo- 
hardenable 
Contiguous Isolation 
Adhesive 
Example Layer Layer Layer Layer 
______________________________________ 
Control A 
37 125 NA.sup.b 
NA.sup.b 
1 30 42 75 50 
2 30 42 55 35 
3 29 50 40 25 
4 37 100 60 35 
5 37 50 60 35 
6 37 100 60 15 
7 37 50 60 15 
8 37 50 20 15 
______________________________________ 
.sup.a mg/dm.sup.2 
.sup.b NA = Not Applicable (Layer is not present in the element.) 
TABLE 3 
______________________________________ 
Effective Dot Area 
Pickoff Cyan Magenta 
Example Defects 30% 50% 30% 50% 
______________________________________ 
Control A 17 50 70 52 73 
1 0 47 68 52 70 
2 0 48 68 50 69 
3 0 48 69 51 72 
4 0 47 69 52 71 
5 0 44 66 48 74 
6 1 48 69 51 72 
7 1 45 66 48 70 
8 7 46 68 49 71 
______________________________________ 
EXAMPLES 9-12 
These examples illustrate photosensitive elements of this invention wherein 
the material used as the contiguous layer was also used as the adhesive 
layer. The procedure of Example 1 was repeated except that the material 
used in the contiguous layer was also coated as the adhesive layer. 
Coating weights are provided in Table 4. The number of pickoff defects and 
the effective dot areas for the cyan and magenta images at 30% dots and 
50% dots using an UGRA target with 150 lines/in (60 lines/cm) are provided 
in Table 5. 
TABLE 4 
______________________________________ 
Coating Weight.sup.a 
Photo- 
hardenable 
Contiguous Isolation 
Adhesive 
Example Layer Layer Layer Layer 
______________________________________ 
9 30 42 75 50 
10 30 62 55 35 
11 30 62 55 50 
12 30 62 55 70 
______________________________________ 
.sup.a mg/dm.sup.2 
TABLE 5 
______________________________________ 
Effective Dot Area 
Pickoff Cyan Magenta 
Example Defects 30% 50% 30% 50% 
______________________________________ 
9 1 48 68 50 71 
10 2 48 69 51 71 
11 1 49 70 53 72 
12 0 49 70 55 73 
______________________________________ 
EXAMPLE 13 
The procedure of Example 9 was repeated except that the isolation layer was 
Elvax.RTM. 140. Coating weights were photohardenable layer, 30 mg/dm.sup.2 
; contiguous layer, 30 mg/dm.sup.2 ; isolation layer, 30 mg/dm.sup.2 ; and 
adhesive layer, 35 mg/dm.sup.2. The number of pickoff defects and the 
effective dot areas for the cyan and magenta images at 30% dots and 50% 
dots using an UGRA target with 150 lines/in (60 lines/cm) are provided in 
Table 6. 
TABLE 6 
______________________________________ 
Effective Dot Area 
Pickoff Cyan Magenta 
Example Defects 30% 50% 30% 50% 
______________________________________ 
13 2 49 68 53 71 
______________________________________ 
EXAMPLE 14 
The general procedure of Example 1 was followed to prepare a photosensitive 
element. The materials were the same as those in Example 1 except (1) the 
isolation layer was Elvacite.RTM. 2042 and (2) the adhesive layer had the 
same composition as the contiguous layer. Coating weights were 
photohardenable layer, 30 mg/dm.sup.2 ; contiguous layer, 42 mg/dm.sup.2 ; 
isolation layer, 60 mg/dm.sup.2 ; and adhesive layer, 25 mg/dm.sup.2. 
A one-color image was formed by removing the support from the 
photosensitive element and laminating the resulting element to 
Cromalin.RTM. CR5 receptor stock (E. I. du Pont de Nemours and Company, 
Wilmington, Del.). The resulting element was exposed, peeled apart, and 
toned with magenta toner as described in Step 6 of Example 1. Exposure was 
carried out through a UGRA target. A special target consisting of a right 
triangle and a square was used to measure pickoff defects. An effective 
dot area was 72% was measured for 50% dots. No pickoff defects were 
observed. 
EXAMPLE 15 
The general procedure of Example 14 was followed to prepare a 
photosensitive element. The materials were the same as those in Example 14 
except that the isolation layer was Elvacite.RTM. 2044. Coating weights 
were photohardenable layer, 30 mg/dm.sup.2 ; contiguous layer, 42 
mg/dm.sup.2 ; isolation layer, 63 mg/dm.sup.2 ; and adhesive layer, 29 
mg/dm.sup.2. An effective dot area was 73% was measured for 50% dots. No 
pickoff defects were observed. 
EXAMPLE 16 
The general procedure of Example 14 was followed to prepare a 
photosensitive element. The materials were the same as those in Example 14 
except that the isolation layer was Elvacite.RTM. 2014. Coating weights 
were photohardenable layer, 30 mg/dm.sup.2 ; contiguous layer, 42 
mg/dm.sup.2 ; isolation layer, 63 mg/dm.sup.2 ; and adhesive layer, 29 
mg/dm.sup.2. An effective dot area of 75% was measured for 50% dots. No 
pickoff defects were observed. 
EXAMPLES 17-20 
The general procedure of Example 14 was followed to prepare a 
photosensitive element. The materials were the same as those in Example 1 
except that the isolation layer was the material indicated in Table 8. 
Coating weights are provided in Table 7. Effective dot areas and pickoff 
defects are provided in Table 8. 
TABLE 7 
______________________________________ 
Coating Weight.sup.a 
Photo- 
hardenable 
Contiguous Isolation 
Adhesive 
Example Layer Layer Layer Layer 
______________________________________ 
17 39 39 62 30 
18 39 45 40 29 
19 39 40 51 18 
20 39 41 90 27 
______________________________________ 
.sup.a mg/dm.sup.2 
TABLE 8 
______________________________________ 
Pickoff 
Example Isolation Layer 
EDAY.sup.a 
Defects 
______________________________________ 
17 Elvacite .RTM. 2014 
72 none 
18 Elvacite .RTM. 2016 
72 minor 
19 Elvacite .RTM. 2044 
72 none 
20 Elvacite .RTM. 2045 
73 none 
______________________________________ 
.sup.a Effective dot area for 50% dots measured for a magenta onecolor 
image. 
EXAMPLE 21 
This example illustrates the preparation and exposure of photosensitive 
elements comprising a precolored photohardenable layer and a photorelease 
layer to form a multicolor negative surprint proof. 
Step 1 
Photorelease Layer (32) 
A solution of WSRN-3000 (70.74% by weight total solids), PVP K-90 (2.19%), 
Goodrite.RTM. K-732 (16.90%), and Pluronic.RTM. L-92 (10.17%), was coated 
onto about 12.2 micron thick clear polyethylene terephthalate coversheet 
using conventional coating techniques. Coating conditions were 0.85% 
solids in water and coating weight about 2 mg/dm.sup.2. After coating the 
element was rewound. An element consisting of a coversheet and a 
photorelease layer was formed. 
Step 2 
Precolored Photohardenable Layer (14) 
The composition of the colored chips used in the precolored 
photopolymerizable layers is provided in Table 9. 
TABLE 9 
______________________________________ 
Ingredient.sup.a 
Yellow Magenta Scarlet 
Cyan Black 
______________________________________ 
Yellow Pigment 
40 -- -- -- -- 
Magenta Pigment 
-- 45 -- -- -- 
Scarlet Pigment 
-- -- 30 -- -- 
Cyan Pigment 
-- -- -- 30 -- 
Raven .RTM. 450 
-- -- -- -- 20 
Raven .RTM. 1035 
-- -- -- -- 20 
Methacrylate 
10 25 10 10 20 
dispersant 
Elvacite .RTM. 2051 
50 30 60 60 40 
______________________________________ 
.sup.a percent by weight 
The coating solutions described in Table 10 were prepared by adding the 
ingredients shown in each of the columns to dichloromethane. The monomer 
and binder, Hetron.RTM. Q6332 and Elvacite.RTM. 2051, were added and 
dissolved first, followed by the colored chips, and then all the other 
ingredients. All solutions were prepared under yellow light. All 
quantities in Table 10 are in weight percent. 
These compositions were each coated onto the element formed in Step 1. Each 
composition was extrusion die coated on top of the photorelease layer 
using conventional coating techniques. The coating solution was about 12% 
solids in dichloromethane. Coating weights are indicated in Table 10. 
Following coating, a polyethylene release film was placed on top of the 
precolored photohardenable layer to protect it until the rest of the 
element was formed. A series of four elements, each consisting of a 
coversheet, a photorelease layer, a precolored photohardenable layer and a 
release film, was formed. These elements corresponded to the four process 
colors which are yellow, magenta, cyan and black. 
TABLE 10 
______________________________________ 
Ingredient.sup.a 
Yellow Magenta Cyan Black 
______________________________________ 
Yellow Chips 25.04 -- -- -- 
Magenta Chips -- 17.66 -- -- 
Scarlet Chips -- 7.49 -- -- 
Cyan Chips -- -- 16.63 -- 
Black Chips -- -- -- 34.49 
Hetron .RTM. Q6332 
53.10 54.31 53.83 54.39 
Elvacite .RTM. 2051 
17.39 16.00 22.99 4.57 
-o-Cl HABI 1.00 1.02 1.02 1.02 
Carboset .RTM. 525 
1.00 1.02 1.02 1.02 
Tinopal .RTM. PCR 
0.26 0.26 0.26 0.26 
2-MBO 0.50 0.51 0.51 0.51 
Tinopal .RTM. SFG 
0.50 0.51 0.51 0.51 
Polyox .RTM. WSRN-3000 
1.00 1.02 1.02 1.02 
Tinuvin .RTM. 328 
0.11 0.11 0.11 0.11 
Zonyl .RTM. FSN 
0.10 0.09 0.09 0.09 
Coating Weight.sup.b 
20 34 34 25 
______________________________________ 
.sup.a percent by weight 
.sup. b mg/dm.sup.2 
Step 3 
Contiguous Layer (16) 
A coating solution of 79.5% Taktene.RTM. 221, 20.0% Gentro.RTM. 1506, and 
0.5% of Irganox.RTM. 1010 (7.7% solids in dichloromethane) was prepared. 
Step 4 
Isolation Layer (18) 
A coating solution of Vinac.RTM. B-15 (22.5% solids in dichloromethane) was 
prepared. 
Step 5 
Adhesive Layer (20) 
A coating solution of 49.5% Taktene.RTM. 221, 50% Gentro.RTM. 1506, and 
0.5% of Irganox.RTM. 1010 (7.7% solids in dichloromethane) was prepared. 
Step 6 
Precolored Photosensitive Element 
The coating solutions for the contiguous layer prepared in Step 3 and the 
isolation layer prepared in Step 4 were coated simultaneously onto about 
14 micron thick silicon treated polyethylene terephthalate release film by 
a conventional multilayer coating technique to form an element consisting 
of silicon treated polyethylene terephthalate release film, isolation 
layer, and contiguous layer. 
The release film was removed from the element formed in Step 2, and the 
precolored photohardenable layer was pressure laminated at room 
temperature to the contiguous layer of the element just formed to form an 
element consisting of coversheet, photorelease layer, precolored 
photohardenable layer, contiguous layer, isolation layer, and silicon 
treated polyethylene terephthalate release film. The coating weight of the 
contiguous layer was 12 mg/dm.sup.2 and the coating weight of the 
isolation layer was 75 mg/dm.sup.2. 
The solution prepared in Step 5 was coated onto a support of about 23 
micron thick silicon treated polyethylene terephthalate release film to 
form an element consisting of adhesive layer and support. The coating 
weight of the adhesive layer was 50 mg/dm.sup.2. 
The polyethylene terephthalate film was removed from the element consisting 
of coversheet, photorelease layer, precolored photohardenable layer, 
contiguous layer, isolation layer, and silicon treated polyethylene 
terephthalate release film and the resulting element was pressure 
laminated at room temperature to the element consisting of adhesive layer 
and support to form a precolored photosensitive element consisting of: 
coversheet, photorelease layer, precolored photohardenable layer, 
contiguous layer, isolation layer, adhesive layer and support. 
Step 7 
One Color Image Formation 
The support was removed from the black precolored photosensitive element 
and the revealed adhesive layer laminated to Du Pont Cromalin.RTM. CRS/3 
receptor stock (E. I. du Pont de Nemours and Company, Wilmington, Del.) to 
form an element consisting of receptor, adhesive layer, isolation layer, 
contiguous layer, black pigmented photopolymer layer, photorelease layer 
and coversheet. This element was placed in a vacuum frame with the 
coversheet up (i.e., facing the light source). A test form consisting of 
an UGRA target (copyright 1982) and the Cromalin.RTM. Comm Guide was 
placed on top of the coversheet with the emulsion side in contact with the 
coversheet. A vacuum was drawn on the element and transparency for 120 sec 
prior to exposure. The element was exposed for about 10 sec with the 
radiation from a 5 kw high pressure mercury vapor lamp (Violux.RTM. 5002S, 
Exposure Systems Company, Bridgeport, Conn.) equipped with a photopolymer 
bulb with a Kokomo filter about 54 in (137 cm) above the element and 
transparency. 
The exposed element was removed from the vacuum frame and placed on a peel 
table that was heated at about 26.degree. C. The coversheet was removed by 
peeling back at 180.degree., i.e., the "peel-back mode", in a smooth, 
continuous motion. The regions which were exposed to actinic radiation 
released from the coversheet during the peeling process to produce a 
black, one color image consisting of receptor, adhesive layer, isolation 
layer, contiguous layer, and black precolored photohardenable layer. The 
unexposed regions remained with the coversheet and were removed. The image 
was the negative of the transparency used for exposure. 
Step 8 
Two color Image Formation 
The support was removed from the cyan precolored photosensitive element and 
the revealed adhesive layer laminated to the one color image formed in 
Step 7 to form an element consisting of receptor, adhesive layer, 
isolation layer, contiguous layer, exposed black precolored 
photohardenable layer, adhesive layer, isolation layer, contiguous layer, 
cyan precolored photohardenable layer, photorelease layer and coversheet. 
The element was exposed and peeled apart as described in Step 7. The 
two-color image produced therefrom consisted of receptor, adhesive layer, 
isolation layer, contiguous layer, black precolored photohardenable layer, 
adhesive layer, isolation layer, contiguous layer, and cyan precolored 
photohardenable layer. 
Step 9 
Three and Four Color Image formation 
The process of Step 8 was repeated, first with the magenta precolored 
photopolymerizable element and then with the yellow precolored 
photopolymerizable element to produce first a three color image and then a 
four-color image. The four color image consisted of receptor, adhesive 
layer, isolation layer, contiguous layer, black precolored photohardenable 
layer, adhesive layer, isolation layer, contiguous layer, cyan precolored 
photohardenable layer, adhesive layer, isolation layer, contiguous layer, 
magenta precolored photohardenable layer, adhesive layer, isolation layer, 
contiguous layer, and yellow precolored photohardenable layer. The image 
was protected by a layer of conventional Cromalin.RTM. off press proofing 
system topcoat. 
Step 10 
Image Evaluation 
Effective dot area was measured for the cyan and magenta portions of the 
30% and 50% regions of the UGRA test targets using a MacBeth RD 918 
reflection densitometer as described in Step 7 of Example 1. The 
resolution was measured on the UGRA target by observing the dots in both 
the high light and shadow dot regions with a conventional 10x graphic arts 
magnification loop. Image quality is provided in Table 11. 
TABLE 11 
______________________________________ 
Dot Effective Dot Area 
Pickoff 
Image Range 30% 50% Defects 
______________________________________ 
Yellow 2-97 56 74 None 
Magenta 3-96 57 76 None 
Cyan 2-97 56 74 None 
Black 2-98 55 75 None 
______________________________________ 
EXAMPLE 22 
A magenta one-color image was prepared by following the general procedure 
of Example 21, Steps 1-7 except that sufficient triacetin to make up 5% by 
weight total solids was added to the composition for the magenta 
precolored photohardenable layer described in Table 10. The element was 
then laminated to CRS/3 receptor stock, exposed, and peeled apart as 
described in Example 21, Step 7. The exposure was for about 10 sec. 
Effective dot areas at 30% and 50% dots were 55% and 73%, respectively. 
The image had 2-97% dots (UGRA target with 60 lines/cm). No pickoff 
defects were observed. 
EXAMPLE 23 
A magenta precolored photosensitive element was prepared by following the 
procedure of Example 21. Coating weights were as follows: photorelease 
layer, 2 mg/dm.sup.2 ; photohardenable layer, 30 mg/dm.sup.2 ; contiguous 
layer, 40 mg/dm.sup.2 ; isolation layer, 75 mg/dm.sup.2 ; and adhesive 
layer, 50 mg/dm.sup.2. A four layer image was prepared following the 
procedure of Example 23 except that the magenta precolored element was 
used for each layer. Each exposure was for about 10 sec. Image quality is 
provided in Table 12. 
TABLE 12 
______________________________________ 
Dot Effective Dot Area 
Pickoff 
Layer Range 30% 50% Defects 
______________________________________ 
First 2-98 54 72 None 
Second 2-98 55 73 None 
Third 2-98 55 74 None 
Fourth 2-98 55 74 None 
______________________________________ 
EXAMPLE 24 
This example illustrates the preparation and exposure of photosensitive 
elements comprising a precolored photohardenable layer to form a 
multicolor positive surprint proof. 
The photosensitive element was prepared as described in Example 1, except 
that the coating solutions for the precolored photohardenable layer 
described in Table 13 were used in place of the composition for the 
photohardenable layer described in Step 1 of Example 1. As described in 
Example 1, the coating solutions were coated onto an electric discharge 
treated polyethylene terephthalate film. 
TABLE 13 
______________________________________ 
Ingredient.sup.a 
Yellow Magenta Cyan Black 
______________________________________ 
Yellow Chips 24.52 1.52 1.23 -- 
Magenta Chips -- 21.86 -- -- 
Cyan Chips -- -- 17.70 -- 
Black Chips -- -- -- 33.44 
Hetron .RTM. Q6332 
39.68 39.11 39.40 37.16 
Elvacite .RTM. 2051 
26.42 28.03 32.23 22.21 
-o-Cl HABI 2.95 3.02 3.00 2.66 
2-MBO 1.70 1.72 1.69 1.72 
Calcofluor .RTM. 
1.97 1.97 1.99 2.01 
White 
Uvitex .RTM. OB 
1.97 1.97 1.99 -- 
FC-430 0.10 0.10 0.10 0.10 
Polyox .RTM. WSRN-3000 
0.69 0.70 0.67 0.70 
Coating Weight.sup.b 
25 26 29 26 
______________________________________ 
.sup.a percent by weight 
.sup.b mg/dm.sup.2 
The support was removed for the black precolored photosensitive element and 
the revealed adhesive layer laminated to Du Pont cromalin.RTM. CRS/3 
receptor stock (E. I. du Pont de Nemours and Company, Wilmington, Del.) to 
form an element consisting of receptor, adhesive layer, isolation layer, 
contiguous layer, black pigmented photopolymer layer, and coversheet. This 
element was exposed to actinic radiation and peeled apart as described in 
Example 21, Step 7, to produce a black, one-color image consisting of 
receptor, adhesive layer, isolation layer, contiguous layer, and black 
precolored photohardenable layer. The exposed regions remained with the 
coversheet and were removed. The image was the positive of the 
transparency used for exposure. 
Following the procedure of Example 21, Steps 8 and 9, a two color, a three 
color, and a four color image were produced. The image was evaluated as 
described in Example 21, Step 10. Image quality is given in Table 14. 
TABLE 14 
______________________________________ 
Dot Effective Dot Area 
Pickoff 
Image Range 30% 50% Defects 
______________________________________ 
Yellow 2-97 56 75 None 
Magenta 2-98 54 73 None 
Cyan 2-97 55 74 None 
Black 2-98 54 74 None 
______________________________________ 
EXAMPLE 25 
A cyan precolored photosensitive element was prepared by following the 
general procedure of Example 1. Coating weights were as follows: 
photohardenable layer, 20 mg/dm.sup.2 ; contiguous layer, 45 mg/dm.sup.2 ; 
isolation layer, 75 mg/dm.sup.2 ; and adhesive layer, 50 mg/dm.sup.2. A 
four layer image was prepared following the procedure of Example 1 except 
that the cyan precolored element was used for each layer. Each exposure 
was for about 10 sec. Image quality is given in Table 15. 
TABLE 15 
______________________________________ 
Dot Effective Dot Area 
Pickoff 
Layer Range 30% 50% Defects 
______________________________________ 
First 2-98 52 72 None 
Second 2-98 54 73 None 
Third 2-98 54 74 None 
Fourth 3-98 54 75 None 
______________________________________ 
Having described the invention, we now claim the following and their 
equivalents.