U.S. patent application number 16/672684 was filed with the patent office on 2021-05-06 for solvent-free flexographic imaging and printing with photoresponsive printing members.
The applicant listed for this patent is Anthony P. KITSON, Kevin RAY. Invention is credited to Anthony P. KITSON, Kevin RAY.
Application Number | 20210129573 16/672684 |
Document ID | / |
Family ID | 1000004590535 |
Filed Date | 2021-05-06 |
![](/patent/app/20210129573/US20210129573A1-20210506\US20210129573A1-2021050)
United States Patent
Application |
20210129573 |
Kind Code |
A1 |
KITSON; Anthony P. ; et
al. |
May 6, 2021 |
SOLVENT-FREE FLEXOGRAPHIC IMAGING AND PRINTING WITH PHOTORESPONSIVE
PRINTING MEMBERS
Abstract
Flexographic printing members amenable to aqueous (or organic)
development do not exhibit the deleterious effects on printing
performance characteristic of some conventional alternatives.
Embodiments of the invention utilize a photopolymerizable layer
comprising, consisting of, or consisting essentially of a
photopolymerization initiator and a water-dilutable (but not
water-soluble) monomer.
Inventors: |
KITSON; Anthony P.; (West
Suffield, CT) ; RAY; Kevin; (Windham, NH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KITSON; Anthony P.
RAY; Kevin |
West Suffield
Windham |
CT
NH |
US
US |
|
|
Family ID: |
1000004590535 |
Appl. No.: |
16/672684 |
Filed: |
November 4, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B41C 1/05 20130101; B41N
2207/14 20130101; B41N 1/12 20130101; B41C 2210/26 20130101 |
International
Class: |
B41N 1/12 20060101
B41N001/12; B41C 1/05 20060101 B41C001/05 |
Claims
1. A method of preparing a printing member, the method comprising
the steps of: providing a printing member comprising (i) an imaged
photomask having an imagewise pattern of opaque and non-opaque
regions, the opaque regions substantially blocking passage
therethrough of actinic radiation, (ii) a support, and (iii)
disposed between the photomask and the support and in contact with
opposed surfaces thereof, a layer of photopolymer polymerizable by
actinic radiation, the photopolymer consisting essentially of an
initiator and a water-dilutable but not water-soluble monomer;
exposing the precursor to actinic radiation through the photomask
to cause polymerization of the photopolymer; and developing the
printing member with an aqueous medium or an organic solvent to
remove only unexposed portions of the photopolymer layer.
2. The method of claim 1, wherein the photopolymer is capable of
emulsification in water.
3. The method of claim 1, wherein the water-dilutable but not
water-soluble monomer is an aliphatic urethane acrylic
oligomer.
4. The method of claim 1, wherein the photopolymer layer also
includes a hydrolyzable binder.
5. The method of claim 4, wherein the hydrolyzable binder is a
rubber.
6. The method of claim 5, wherein the rubber is butadiene maleic
anhydride copolymer.
7. The method of claim 1, wherein the photopolymer layer further
comprises a dye.
8. The method of claim 1, wherein the photopolymer layer further
comprises an anti-oxidant.
9. The method of claim 1, wherein the printing member is a
flexographic printing member.
10. The method of claim 1, wherein the printing member is a
letterpress printing member.
11. A printing member comprising: a laser-ablatable layer
comprising a material that absorbs laser radiation; a support; and
disposed between the laser-ablatable layer and the support and in
contact with opposed surfaces thereof, a layer of photopolymer
polymerizable by actinic radiation, the photopolymer comprising an
initiator and a water-dilutable but not water-soluble monomer,
wherein the photopolymer is developable by organic and aqueous
solvents and combinations thereof.
12. The printing member of claim 11, wherein the laser-ablatable
layer is ablatable by IR radiation.
13. The printing member of claim 12, wherein the laser-ablatable
layer consists essentially of a polymer and carbon black dispersed
therein.
14. The printing member of claim 11, wherein the photopolymer layer
also includes a hydrolyzable binder.
15. The printing member of claim 14, wherein the hydrolyzable
binder is a rubber.
16. The printing member of claim 15, wherein the rubber is
butadiene maleic anhydride copolymer.
17. The printing member of claim 16, wherein the butadiene maleic
anhydride copolymer is a butadiene/styrene/maleic anhydride
copolymer.
18. The printing member of claim 15, wherein the rubber is
polyisoprene maleic anhydride rubber.
19. The printing member of claim 11, wherein the photopolymer layer
further comprises a dye.
20. The printing member of claim 11, wherein the photopolymer layer
further comprises an anti-oxidant.
Description
BACKGROUND OF THE INVENTION
[0001] Flexography utilizes resilient relief members to transfer an
image from a printing member to a recording medium. As in
letterpress printing, a flexographic member or plate has a surface
comprising an "imagewise" pattern of raised features. Ink is
applied to and carried by these raised features and transferred
therefrom to the image receiver. Although developed primarily for
printing packaging materials, flexography is today used in a wide
variety of applications and on recording media such as paper,
corrugated board, films, foils, and laminates.
[0002] Flexographic printing plates can be prepared from
photosensitive elements comprising a photopolymerizable layer
containing an elastomeric binder, a monomer, and a photoinitiator,
interposed between a support and a cover sheet or multilayer cover
element. A standard process of making such photosensitive elements
is described in U.S. Pat. No. 4,460,675; as set forth therein, a
previously extruded photopolymerizable composition is fed into the
nip of a calender (i.e., a series of hard, high-pressure rollers in
rolling contact) and is pressed between a support and a multilayer
cover element to form a photopolymerizable layer. Upon imagewise
exposure of the photosensitive element to actinic radiation through
a photomask, the exposed areas of the photopolymerizable layer
become insolubilized. Treatment with a suitable solvent or solvent
mixture removes the unexposed areas of the photopolymerizable
layer, leaving a printing relief which can be used for flexographic
printing. See also U.S. Pat. Nos. 4,323,637, 4,427,759, and
4,894,315.
[0003] The photomask may be ablatable by, for example, infrared
(IR) radiation but is opaque to actinic (e.g., ultraviolet (UV))
radiation. This IR-sensitive layer may be imaged digitally, using a
laser. Subsequent overall exposure of the photopolymerizable
element to actinic radiation through the imagewise-ablated
photomask produces an imagewise pattern of hardened regions;
unpolymerized areas that did not receive exposure, and remaining
areas of the IR-sensitive layer, are washed away during
development. Following drying, the flexographic printing plate is
ready for use.
[0004] Developing the exposed photosensitive element with a solvent
or solvent mixture is time-consuming, since drying for extended
period (0.5 to 24 hours) is typically necessary to remove entrained
developer solution. In addition, these developing systems produce
potentially toxic by-product wastes (both the solvent and any
material carried off by the solvent). For printing of food
packaging, elimination of solvent residue on the finished plate is
also crucial. Accordingly, many flexographic plates use
water-soluble photopolymerizable layers to permit aqueous
development. While convenient, such plates can exhibit poor
chemical resistance and other vulnerabilities to image
integrity.
SUMMARY OF THE INVENTION
[0005] The present invention is directed toward achieving the
benefits of aqueous development without the accompanying
deleterious effects on printing performance. Embodiments of the
invention utilize a photopolymerizable layer comprising, consisting
of, or consisting essentially of a photopolymerization initiator
and a water-dilutable (but not water-soluble) monomer. Optionally,
the photopolymerizable layer may include a water-hydrolyzable
binder. Other optional ingredients that may be present are binders
such as natural and synthetic rubbers, monomers and oligomers,
dyes, and/or anti-oxidants. None of these optional materials
contributes to function or structure, so a formulation consisting
essentially of a photopolymerization initiator and a
water-dilutable (but not water-soluble) monomer may include any or
all of these optional materials.
[0006] Advantages offered by embodiments of the invention include
environmentally friendly development (without organic solvents),
fast development times, good image integrity with high resolution,
good ink receptivity, and good chemical resistance. Surprisingly,
even when emulsified, the photopolymer composition can be developed
using organic developers despite the presence of a monomer selected
to permit aqueous processing. The approach described herein may be
applied not only to flexographic printing plates but also to
lithographic printing plates, letterpress plates, and
raised-feature photopolymer signs such as Braille signs.
[0007] Accordingly, in a first aspect, the invention relates to a
method of preparing a printing member. In various embodiments, the
method comprises the steps of providing a printing member
comprising (i) an imaged photomask having an imagewise pattern of
opaque and non-opaque regions, the opaque regions substantially
blocking passage therethrough of actinic radiation, (ii) a support,
and (iii) disposed between the photomask and the support and in
contact with opposed surfaces thereof, a layer of photopolymer
polymerizable by actinic radiation, the photopolymer consisting
essentially of an initiator and a water-dilutable but not
water-soluble monomer; exposing the precursor to actinic radiation
through the photomask to cause polymerization of the photopolymer;
and developing the printing member with an aqueous medium or an
organic solvent to remove only unexposed portions of the
photopolymer layer.
[0008] The photopolymer may be capable of emulsification in water.
For example, the water-dilutable but not water-soluble monomer may
be an aliphatic urethane acrylic oligomer. In some embodiments, the
photopolymer layer also includes a hydrolyzable binder, e.g., a
natural or synthetic rubber. For example, the rubber may be
butadiene maleic anhydride copolymer. In various embodiments, the
photopolymer layer further comprises a dye and/or an anti-oxidant.
The printing member may be a flexographic printing member or a
letterpress printing member.
[0009] In another aspect, the invention pertains to a printing
member comprising, in various embodiments, a laser-ablatable layer
comprising a material that absorbs laser radiation; a support; and
disposed between the laser-ablatable layer and the support and in
contact with opposed surfaces thereof, a layer of photopolymer
polymerizable by actinic radiation. The photopolymer comprises an
initiator and a water-dilutable but not water-soluble monomer, and
the photopolymer is developable by organic and aqueous solvents and
combinations thereof.
[0010] The laser-ablatable layer may be ablatable by IR radiation,
and may consist essentially of a polymer and carbon black dispersed
therein. In various embodiments, the photopolymer layer also
includes a hydrolyzable binder, e.g., a rubber such as butadiene
maleic anhydride copolymer or polyisoprene maleic anhydride rubber.
For example, a butadiene maleic anhydride copolymer may be a
butadiene/styrene/maleic anhydride copolymer.
[0011] In various embodiments, the photopolymer layer further
comprises a dye and/or an anti-oxidant. The printing member may be
a flexographic printing member or a letterpress printing
member.
[0012] As used herein, the term "free radical" refers to a highly
reactive atom or molecule with at least one unpaired electron. A
"free-radical polymerization mechanism" means initiation of
polymerization by free radicals that attack short-chain oligomers
with ethylenic unsaturation; these free radical species are known
as "free-radical initiators."
[0013] "Water-dilutable" has the same meaning as "water-reducible,"
referring to a material that may be diluted with water--i.e., its
concentration may be reduced uniformly by addition of water. A
material that is water-dilutable without being water-soluble means
that the material disperses uniformly in water but remains as a
separate phase (that may, for example, be filtered) with a particle
size of at least 1 nm and in some cases at least 1 .mu.m, with
water as the continuous phase. For example, a material capable of
emulsification is water-dilutable but not water-soluble. A material
that is infinitely water-dilutable disperses uniformly in water
regardless of the volume of water relative to that of the
infinitely water-dilutable material.
[0014] The term "monomer" refers generally to a functional chemical
unit that may be covalently linked with other such units to form a
polymer. However, the term is used broadly to include oligomers,
which include one or more repeating units but can themselves be
linked to form a polymer.
[0015] The term "plate" or "member" refers to any type of printing
member or surface capable of recording an image defined by regions
exhibiting differential affinities for ink and/or fountain
solution. Suitable configurations include the traditional planar or
curved plates that are mounted on the plate cylinder of a printing
press, but can also include seamless cylinders (e.g., the roll
surface of a plate cylinder), an endless belt, or other
arrangement.
[0016] The term "hydrophilic" is used in the printing sense to
connote a surface affinity for a fluid which prevents ink from
adhering thereto. Such fluids include water for conventional ink
systems, aqueous and non-aqueous dampening liquids, and the non-ink
phase of single-fluid ink systems. Thus, a hydrophilic surface in
accordance herewith exhibits preferential affinity for any of these
materials relative to oil-based materials.
[0017] The term "substantially" or "approximately" means.+-.10%
(e.g., by weight or by volume), and in some embodiments, .+-.5%.
The term "consists essentially of" means excluding other materials
that contribute to function or structure. For example, a
radiation-sensitive composition consisting essentially of a
polymerizable component, an initiator composition, a
radiation-absorbing component and a polymeric binder may include
other ingredients, such as a catalyst, that may perform important
functions but do not constitute part of the polymer structure of
the composition following polymerization. Percentages refer to
weight percentages unless otherwise indicated.
DESCRIPTION OF DRAWINGS
[0018] The foregoing discussion will be understood more readily
from the following detailed description of the disclosed
technology, when taken in conjunction with the following drawings,
in which:
[0019] FIG. 1 schematically illustrates preparation of a
flexographic printing plate according to embodiments of the
invention.
[0020] FIG. 2 is a sectional side elevation illustrating the
structure of a flexographic printing plate according to embodiments
of the invention.
DETAILED DESCRIPTION
1. Preparation and Use of Flexographic Plates
[0021] Refer to FIG. 1, which illustrates a representative process
for imaging a flexographic printing plate 100. The plate 100
includes a laser-ablation layer 105, a photopolymerizable layer
110, an adhesive and anti-halation layer 115, and a polymer base
120. First, the base 120 of the plate 100 is exposed to actinic
radiation from, e.g., a source 125 of UV radiation in order to
harden the base 120. The orientation of the plate 100 is then
reversed and the ablation layer 105 is selectively removed by a
laser 130 emitting, for example, in the near-IR region. The
ablation layer contains a material, such as carbon black in an
acrylic binder, that absorbs laser radiation and catastrophically
overheats, removing the layer 105 where exposed or rendering it
easily removed. The output of the laser 130 can be provided
directly to the plate surface via lenses or other beam-guiding
components, or transmitted to the surface of a blank printing plate
from a remotely sited laser using a fiber-optic cable. A controller
135 and associated positioning hardware maintain the beam output at
a precise orientation with respect to the plate surface, scan the
output over the surface, and activate the laser at positions
adjacent selected points or areas of the plate 100. The controller
135 responds to incoming image signals corresponding to the
original document or picture being copied onto the plate 100,
activing the laser 130 to ablate plate regions that will not
receive ink during printing. The image signals are stored as a
bitmap data file on a computer. Such files may be generated by a
raster image processor ("RIP") or other suitable means.
[0022] Following imaging, the ablation layer 105 functions as a
mask when the now-reversed plate 100 is again exposed to the source
125 of actinic radiation. Radiation admitted through removed
regions of the ablation layer 105 polymerizes the underlying layer
110, hardening it. The effects of the radiation expand with depth
in the photopolymerizable layer 110 so that a floor is formed
beneath the unexposed regions, thereby creating a series of raised
regions 130 and recesses 135. Remaining portions of the imaged
ablation layer 105 and unpolymerized regions of layer 110 are then
removed by brushing and washing in a "washout" step, leaving a
raised pattern of features 140 that will accept and transfer ink
during printing. The plate may now be dried, e.g., under a hot-air
dryer 145, and subjected again to the source 125 of actinic
radiation to complete the photo-curing process.
[0023] Different types of UV light may be employed at different
points in the process. The first and second exposures may involve a
combination (typically the same combination) of UVA or UVB, for
example, and the final exposure may be UVC light ("germicidal UV,"
100 to 280 nm, usually 280 nm).
[0024] Optionally, a very thin additional layer may be included
above the photopolymer layer 110 but below the ablative layer 105.
This "anti-slip" layer may protect the user and equipment from
encountering the photopolymer layer 110, which may be tacky even
after the second UV light exposure. This layer, if included, is
removed in the washout step. Another optional layer is a plastic
coversheet over the ablative layer 105, which provides protection
prior to use and its peeled off before or after the ablative layer
105 is imaged.
[0025] A representative flexographic printing plate 200 in
accordance with embodiments of the invention is shown in FIG. 2 and
includes a polymer base layer 220, an anti-halation layer 215, a
polymeric ablation layer 205 and, sandwiched therebetween, a
photosensitive layer 210 comprising a water-dilutable monomer or
oligomer. The polymer base layer 220 may be, for example,
polyethyelene terephthalate (PET), polycarbonate, polyethylene
napthalate, polybutylene terephalate, polyimide, and
polyetherketone with a thickness ranging from 0.05 to 0.3 mm. The
polymeric ablation layer 205 may be a carbon-loaded acrylic,
polyvinyl alcohol or cellulosic resin having a thickness of 0.1 to
5 microns and a loading level of 1 to 75%, and may be coated with
an optional anti-slip layer 225. Alternatively, a photomask may be
employed.
[0026] The photosensitive layer 210, described in greater detail in
the examples below, may have a thickness of 0.1 to 10.0 mm. In
addition to the water-dilutable (but not water-soluble) monomer,
the photosensitive layer may include a hydrolyzable binder such as
a natural or synthetic rubber, e.g., butadiene maleic anhydride
copolymer or polyisoprene maleic anhydride rubber. In this case,
other monomers may be part of the copolymer; for example, the
synthetic rubber may be a butadiene/styrene/maleic anhydride
copolymer. In some cases, the photopolymer layer 210 can be a
stacked series of different layers. The reflection-preventing
anti-halation layer 215 may also promote adhesion between the base
220 and the photopolymer layer(s) 210. An anti-slip layer 230 may
optionally be included or, in some embodiments, the ablation layer
205 may perform the anti-slip barrier function. In still other
embodiments, the ablation layer 205 may be omitted altogether.
[0027] The foregoing approach may be applied to lithographic or
letterpress plates. A letterpress plate may be structurally similar
to a flexographic plate but the support 220 is typically magnetic
steel rather than polyester and the exposed photopolymer 210 may be
harder than that of a flexographic plate; whereas a typical
flexographic plate may have a hardness of about 65-75 Shore A, a
letterpress plate may have a hardness of about 65 Shore D.
2. Examples
[0028] A series of photopolymer compositions were prepared using
the following formulations listed in Table 1 (with all units in
grams). Component descriptions and sources appear in Table 2.
TABLE-US-00001 TABLE 1 Ingredient Composition 1 2 3 4 5 6 7 8 9 10
1 76.28 5.00 7.50 0.50 0.50 0.005 0.00 7.50 0.00 52.72 2 77.25 0.00
15.00 0.75 0.75 0.008 22.73 0.00 11.25 72.27 3 92.48 0.00 9.75 0.75
0.75 0.004 0.00 15.00 9.00 72.27
TABLE-US-00002 TABLE 2 Ingredient No. Material Source 1
Tetrahydrofuran Sigma Aldrich, Milwaukee, WI 2 Trimethylolpropane
Sigma Aldrich, ethoxylate triacrylate Milwaukee, WI 3 SARTOMER
CN307 Sartomer, Exton, PA (hydrophobic acrylate ester) 4 IRGACURE
651 Ciba, Newport, DE photoinitiator (2,2-dimethoxy- 2-phenyl
acetophenone) 5 Butylated hydroxytoluene Sigma Aldrich, Milwaukee,
WI 6 Valifast Blue 1605 (spirit Orient Corporation color) of
America, Seaford, DE 7 NEOREZ 1391 (polyurethane TCI Materials,
supplied at 35% solids in Shrewsbury, MA water) 8 POLYVEST EPMA120
Evonik, Parsippany- (polybutadiene resin) Troy Hills, NJ 9 BOMAR
XR9416 (oligomer Dymax, Torrington, capable of emulsification in CT
water) 10 NIPOL LX111NF (latex Zeon Corporation, supplied at 55%
solids in Tokyo, Japan water)
Example C1
[0029] Ingredients 1-9 of Composition 1 were dissolved/dispersed in
a beaker. Ingredient 10 was then added to the solution slowly while
stirring with a Silverson L5 high shear lab mixer. The resulting
slurry was poured into a glass dish and placed in an oven for 24
hours at 75.degree. C. to dry.
[0030] The resulting composition was compounded into sheet form
using a two-roll mill available from Reliable Rubber and Plastic
Manufacturing Co, North Bergen, N.J. The roll nip was set to
produce a photosensitive sheet with a thickness of approximately 70
mils (0.070 inch). The resulting sheet was laminated to transparent
polyester sheets to provide a flexographic printing construction
(lacking the ablation mask shown in FIG. 1), with the 70-mil
photosensitive layer sandwiched between a PET base layer of 7 mils
thickness and a 2-mil PET cover film coated with a release
layer.
[0031] Imaging was carried out on a Thiemer COPYMAT exposure unit
equipped with a THS3007 3000W metal halide UV lamp, available from
Thiemer GMBH, Birstein, Germany.
[0032] Back exposure: the imagable composition was placed cover
sheet down in the light exposure unit and exposed under vacuum for
90 seconds with light intensity set at 50%.
[0033] Main exposure: the composition was then placed base sheet
down in the exposure unit. A Stouffer graphic-arts test strip was
placed on top of the cover sheet, as was a photographic negative
imaged with a 65-line screen calibrated screen tint. The
photopolymer was then exposed under vacuum for 18 minutes with
light intensity set at 50%.
[0034] Development: this refers to removal of unexposed (and
therefore unpolymerized) photopolymer. The cover sheet was removed,
and the patterned photopolymer was placed in a glass dish
containing heptane. It was scrubbed with a stiff brush until a
relief image formed. The sheet was then dried in an oven at
75.degree. C. for 15 minutes.
[0035] Post-exposure: the integrity of the imaged polymer was
further enhanced by post-exposure to UV radiation. The sheet was
placed base sheet down in the exposure unit and exposed for 6
minutes under vacuum with light intensity set at 50%.
Example C2
[0036] Another sheet using Composition 1 ingredients was produced
using the same procedures as in Example 1, except the patterned
sheet was developed in water containing 5% by weight Stop and Shop
brand (54 Hazard Avenue, Enfield, Conn. 06082) dishwasher detergent
warmed to 50.degree. C.
Example 3
[0037] A sheet using Composition 2 was produced according to the
procedures set forth in Example 1.
Example 4
[0038] A sheet using Composition 2 was produced according to the
procedures set forth in Example 2.
Example 5
[0039] A sheet using Composition 3 was produced according to the
procedures set forth in Example 1, except the patterned sheet was
developed in water containing 2% by weight Stop and Shop brand
dishwasher detergent and 2% AJAX Ultra Triple Action liquid dish
soap (Colgate-Palmolive, New York City, N.Y. 10022) warmed to
50.degree. C.
Example 6
[0040] Another sheet using Composition 3 was produced according to
the procedures set forth in Example 1, except the patterned sheet
was developed in plain water warmed to 50.degree. C.
[0041] Evaluation
[0042] The photosensitivity of the sheet was determined by reading
the Stouffer test strip. The shore hardness of the imaged
photosensitive sheet was measured with a durometer. The ease of
development of the composition was graded on a scale of 1 to 5 with
1 corresponding to excellent development (the unexposed material
was removed quickly and easily) and 5 representing no development
at all. The quality of the image was assessed under magnification
and also rated on a scale of 1 to 5 with 1 being full reproduction
of the photographic mask and 5 being no image.
Results for Examples 1-6
TABLE-US-00003 [0043] Stouffer shore A ease of image Example
reading hardness development quality Comments 1 solid 8, clear 14
70 2 2 2 -- 70 5 -- Does not develop in detergent 3 solid 8, clear
15 75 2 2 4 solid 8, clear 16 75 2 3 develops (rather slowly) in
detergent 5 solid 6, clear 17 68 1 1 easy to develop and excellent
image quality 6 solid 10, clear 18 68 2 2
[0044] Printing with Example 6
[0045] In one experiment, a rubber roller was coated in Titan black
ink, supplied by Spinks Ink Company, Addison, Ill. The ink was
rolled across the surface of the patterned sheet obtained in
Example 6. The sheet was placed ink-side-down onto a piece of paper
and pressure was applied to reveal a print with good image
fidelity.
[0046] In another experiment, one part Smooth Lith, available from
Van Son, Islandia, N.Y., was added to 9 parts Titan black ink to
reduce the tackiness. A Heidelberg GTO printing press was equipped
with the ink and the patterned sheet obtained in Example 6 was
attached to the plate cylinder using double-sided tape. All packing
was removed from the blanket cylinder. The press was run dry (no
fountain solution). On the first revolution a good image was
transferred from the plate to the blanket. When the blanket was
contacted with paper, an image with good fidelity was formed. In
this way, multiple copies were made.
[0047] Discussion of Results
[0048] The formulations of Examples 1 and 2 do not contain a
monomer capable of emulsification in water. The composition will
develop in organic solvent but will not develop aqueously. Examples
3 and 4 contain a monomer capable of emulsification in water,
specifically, an aliphatic urethane acrylic oligomer, BOMAR XR9416.
The composition will develop in solvent or aqueous developer.
Examples 5 and 6 contain a monomer capable of emulsification in
water and a binder capable of hydrolysis in water (XR9416 and
Polyvest MA75). The composition will develop easily in aqueous
developer or even pure water.
[0049] Examples 7 and 8 demonstrate the composition can function as
a printing plate.
[0050] Although the present invention has been described with
reference to specific details, it is not intended that such details
should be regarded as limitations upon the scope of the invention,
except as and to the extent that they are included in the
accompanying claims.
* * * * *