Note: Descriptions are shown in the official language in which they were submitted.
-
2~473~8
METHOD FOR MANUFACTURING SUPER}OR INK-WATER
BALANCE AND Ar~r~Ar~TNR-REsIsTANT PS PLATES
Background of the Invention
This invention relates to photosensitive
printing plates and, more particularly, to processes and
composltions for making such plates which are P~pc.ri;-l ly
adapted to be resistant to ~lk~lin~ fountain solutions,
alkaline-related chemicals and solvent chemicals used in
the plate room and press room, and to provide an improved
ink-water balance.
A lithographic printing plate is made by mixing
a photosensitive material such as a diazo resin with a
binder and other ingredients to produce a photosensitive
coating which can be applied to an aluminum or other
substrate, which has been pretreated to render it highly
hydrophilic. Upon imagewise exposure of the printing
plate, the areas on the plate exposed to the light are
cured and become insoluble in a developer applied to the
plate after light exposure. The developer solubili~es,
and thereby, removes, the uncured photosensitive material
which had been protected from the light by the negative,
creating hydrophilic areas where the aluminum substrate
has been uncovered and oleophilic areas where the cured
photosensitive coating remains. The contrasting
oleophilic and hydrophilic surface areas on the developed
plate allow for preferential retention of a greasy image-
forming substance by an image area, and retention of an
aqueous ~ _ in~ solution by a non-image area, providing
a means for printlng by use of water and fatty ink.
Comparative Example 4 describes a prior art
lithographic prlnting plate particularly suitable for
newspaper printing. Such a printing plate provides for
qulck and easy development and exceptional print
resolution for newspaper printing when used with acid or
35 neutral fountain solutions. However, the above-described
~ ~ 21~388
printing plate exhibits only poor resistance to alkaline
fountain solution~ and some plate and press room
chemistry and, therefore, does not work well when used
with alkaline-based fountain solutions such as Rycoline,
5 Anchor or PSI alkaline fountain solutions, and does not
stand up well to alkaline and other plate and press-room
chemicals in common use such as certain plate cleaner
solutions. Eiurther, while such printing plates are
comparable to others on the market in terms of the ink-
10 water balance they produce during printing, a significantwaste of paper occurs during "warm starts" (press
stoppages and restarts ) as the water and ink used for
printing are brought into balance. Additionally, a high
water level must be reached before the ink-water balance
15 is realized, thus necessitating the use of greater
amounts of ink during printing.
Thus, the discovery of a photosensitive
printing plate which has the attributes described above
of easy developability and superior print resolution, but
20 which is resistant to alkaline fountain solutions and
other press-room chemicals, particularly such a plate
which produces an improved ink-water balance is highly
desirable. Moreover, the discovery of a photosensitive
printing plate exhibiting one or both of these advantages
25 has been the object of considerable interest in the
industry .
Summary of the Irvention
Among the several objects of the invention,
therefore, may be noted the provision of photosensitive
30 printing plates which exhibit improved resistance to
alkaline fountain solutions and other alkaline and press-
room chemicals, and produce an i 1 uv~d ink-water balance
resulting in reduced roll up time, less spoilage of
paper, lower requirements for water and ink in the
35 printing of the plates and faster clean up; the provision
~ 2147388
o~ uved photosensltive compositions and substrates
for use in producing such plates; and the provision of
methods for producing such improved photosensitive
printing plates and substrates.
Briefly, therefore, the present invention is
directed to a novel photosensitive printing plate. The
printing plate comprises a layer of a photosensitive
composition containing a photosensitive diazo resin and a
binder on an aluminum substrate. The photosensitive
composition contains ~a) a photosensitive diazo resin
comprising a cnn~pn~tion product of an aromatic
diazonium salt, a co-polymerizable compound free of
7nni groups, and an active carbonyl-containing
compound and (b) a binder comprising a high molecular
weight acrylic co-polymer. The aluminum substrate has
been grained, etched by application of a caustic solution
containing from about 1.0% to about 4.759c of an alkali
metal hydroxide by weight, and hydrophilized.
The present invention is further directed to an
alkaline-resistant photosensitive composition. The
photosensitive composition comprises:
(a) a photosensitive diazo resin which is a
copolymer containing the recurring monomer units having
the general formula (I) --
N2C ~XC ~\ / \
~ H ~ H
wherein Rl, R2, and R3 each denote separately a llydl uyt:l~
atom, a halogen atom, an alkyl group having from l to 3
carbon atoms, or an alkoxy group having from 1 to 6
carbon atoms, X denotes PF6 or BF4, R is a hydrogen atom,
5 an alkyl group having 1 or 2 carbon atoms or a phenyl
group, at least one of R4 and R5 is hydroxyl or carboxyl
and the other is a hydrogen atom, hydroxyl, carboxyl, an
alkyl group having from 1 to 3 carbon atoms, an alkoxy
group having from 1 to 6 carbon atoms, halogen, -SO3H or
10 its salt, or -S02H or its salt, R6 is a llydlug~ll atom, an
alkyl group having l or Z carbon atoms or a phenyl group,
and the ratio of m to n is from about 70:30 to about
85:15, and the dia~o resin has an average molecular
weight of from about 2,000 to about 3,000 and
~b) a binder comprising a high molecular weight
acrylic co-polymer, wherein the ratio of (a) to (b) by
weight is from about 0.033/1 to about 0.17/lØ
In a preferred embodiment of the photosensitive
composition of the invention, (b1 is a binder comprising
20 an acrylic copolymer containing the recurring monomer
units having the general formula ( II ) --
- C H 2 - C - ) j C - C H 2 - C - ~ k - R 9
CN COOP COOH
wherein R7, RB, and R9 are lntl~rc~nrl~ntly a
hydrogen atom or an alkyl group having from l to 3 carbon
25 atoms, and R10 is an alkyl group having from l to 3 carbon
2147388
atoms or a phenyl group,; is a number from 20 to 30, k
i8 a number from 50 to 70, and l a numoer from 4 to 14,
the binder polymer has an average molecular weight of
from about 50,000 to about 150,000, and has an acid
5 number of from 20-lO0.
The invention also includes a method for
producing a photosensitive printing plate. The method
comprises the steps of graining an aluminum substrate,
etching the grained substrate by contacting it with a
10 caustic solution containing from about l . 096 to about
4. 75% of an alkali metal hydroxide by weight,
hydrophilizing the aluminum substrate, coating the
substrate with a layer of a photosensitive composition
containing a photosensitive diazo resin and a binder as
15 described above, and drying the photosensitive printing
plate .
In an alternative: -af- L the invention is
directed to a method for producing a photosensltive
printing plate. The method comprises the steps of
20 graining an aluminum substrate, etching the grained
substrate by contacting it with a caustic solution
containing from about 1.0% to about 4.75% of an alkali
metal hydroxide by weight at a temperature of f rom about
45 C to about 80 C, hydrophilizing the aluminum
25 substrate, coating the substrate with a layer of a
2l47388
photosensitive composition containing a photosensitive
diazo resin and a binder~ and drying the photo6ensitive
printing plate.
The invention is further directed to a novel
treated aluminum substrate for use in a lithographic
printing plate. The novel treated aluminum substrate has
an optical density reading of at least about 0 . 38 and is
prepared by the steps of graining the aluminum substrate,
etching the grained substrate by contacting it with a
caustic solution containing from about 1. 0% to about
4. 75% of an alkali metal hydroxide by weight, and
hydrophilizing the aluminum substrate.
The invention is further directed to methods
for the preparation of such treated aluminum ~ubsLLaLes,
as described above, adapted for use ln such
photosensitive printing plates.
Other ob~ects and features will be in part
apparent and in part pointed out hereinafter.
Description of the Preferred Embodiment
It has been discovered in accordance with the
invention that by combining a particular photosensitive
coating containing an increased ratio of diazo resin to
binder with a less aggres~31vely etched aluminum
substrate, a photosensitive printing plate i8 produced
Z5 which exhibit~ greatly ~nhF-nf~e~ resistance to alkaline
fountain solutions and other alkaline and press-room
~ 21~7388
rhPm; rAl ,~, thus permitting longer run times and reduced
"down" times during which printing presses must be
stopped to replace worn out plates. Moreover, the
modi f ied substrate contributes to an improved ink-water
5 balance, allowing for faster roll up, less waste of paper
during start up, reduced rnn! tion of ink and easier
clean up.
The photosensitive printing plate of this
invention comprises a photosensitive composition as
10 described below layered or coated onto a grained, etched,
and hydrophilized aluminum substrate. The aluminum
sheets which may be employed as substrates include those
which are made from aluminum alloys such as Aluminum
Association alloys 1050, 1100 and 3003. Sheets used for
15 printing plate substrates preferably have a thickness of
from 6 to 20 gauge (1 gauge = 0.001 in).
In the practice of the instant invention, the
aluminum sheet is prepared for use as a substrate by
subjecting it to a series of treatments which includes
20 degreasing, graining, etching and hydrophili~ing its
surface, and preferably also includes an anodizing step
after etching.
The foregoing ~ minllm plates are pretreated
with a degreaser such as sodium silicate, sodium
25 hydroxide or various surfactants in order to remove any
oil adhering to the surface of the aluminum sheets.
38$
After degreasing, the aluminum substrate is
grained to create a "roughened" surface having pit8 and
peaks which provides a better "grip" for the
photosensitive coating and also creates places for
miniature ink and water reservoirs on the surface of the
developed plate. In a preferred embodiment, 8uch surface
roughening is produced by mechanically graining the
surface, e.g., by brush graining using a pumice slurry as
an abrasive, wire brush graining, or ball graining.
However, it may also be produced by chemical or
electrolytic graining techniques or by a combination of
such methods. Preferably, the aluminum sheets are
grained until reaching an optical density of from about
0.20 to 0.30, and most preferably from about 0.23 to
0 . 27 .
According to the invention, the grained
aluminum substrate is then etched using a caustic aqueous
solution containing, or consisting essentially of, an
alkali metal hydroxide, such as potassium hydroxide or,
preferably, sodium hydroxide. Prior to the instant ~=
invention it was widely believed that a relatively high
concentration of alkali -- e.g., one above 10%, was
required to aggressively etch the plate and create a
substrate background sufficiently "white" for plates of
the type described herein. Surprisingly, however,
applicant has discovered that le88 than half the
concentration of alkali previously believed to be
~ ~ 2~388
desirable provides for more than adequate shade contrast
and unexpectedly contributes to greater alkaline
resistance and to an i _ LVV-:d ink-water balance for the
photosensitive printing plate. Accordingly, the
concentration of the alkali metal hydroxide in the
caustic solution of the invention ifi from about 1 to
about 4.7596 by weight, preferably 2 to 4.4%, and most
preferably 3.9 to 4.1%. For optimum results, the caustic
solution is preheated to a t _~ ~-uLe between about 45
C and about 80 C, preferably from about 50 C to about
60 C, and most preferably at about 55' C, prior to the
etching treatment. The grained aluminum is immersed in
or otherwise contacted with the caustlc solution for a
time sufficient to obtain an optical density of at least
0.38, as measured by a densitometer, e.g., as sold by
Litho-Tronics, Wheeling, Illinois, using a yellow filter.
Under the conditions described above, contact time is
preferably for from about 4 to about 12 seconds, and most
preferably from about 6 to about 8 seconds. An alkaline
residue and film of smut left on the surface of the
aluminum substrate after graining and etching may readily
be neutralized and removed, respectively, by application
of an acidic solution, such as a 10-1596 nitric acid
solution, followed by washing with water.
If desired, the grained and etched aluminum
substrate may be anodically oxidized, e.g., in an acidic
solution such as one containing sulfuric acid, phosphoric
2~7388
acid, oxalic acid or a mixture of two or more of these or
other oxidizing compounds. In a preferred procedure, the
substrate i8 passed through an anodizing bath containing,
e.g., 10 to 20% sulfuric acid at a temperature of from
5 25D C to 50 C, resulting in the deposition of an
nllm oxide film of between about 160 and 240 mg/ft2 on
the substrate ' s surface.
While the anodized plate already has been
rendered somewhat hydrophilic, it is advantageous to
10 subject its surface to treatment with silicates such as
sodium or potassium silicate, to render it even more
hydrophilic. In a preferred ~ ~'i l, the sheet is
immersed in a 2 to 5i aqueous solution of sodium silicate
at a temperature of between about 75 to 90 C, followed
15 by rinsing in a hot water bath (e.g., at 75 C to 98 C).
Substrates 80 treated provide improved ink-
water balance, thereby providing for reduced roll up
time, less spoilage of paper, lower ink and water
requirements and faster clean up. Moreover, they
20 contribute to alkaline resistance when employed in a
printing plate subjected to alkaline fountain solutions.
According to the invention, the aluminum
substrate having been treated as described above, is then
coated with a photosensitive composition. The
25 photosensitive composition of the present invention
comprises a diazo resin and a binder mixed together with
other ingredients such as a solvent, a dye or pigment,
2~7388
ll
and an acld stabilizer. The diazo resin is substantially
organic solvent-soluble and water insoluble, and
preferably comprises a rnnti~n~tion product of an
aromatic ~i~7nn~llm sal~, a co-polymerizable r~ ' free
5 of diazonium groups, and an actlve carbonyl-contalning
compound such as formaldehyde or acetaldehyde. In a
preferred: -Ai - t of the invention the diazo resin is
a copolymer containlng the recurring monomer unlts havlng
the general formula ( I ):
N C ~ ) X
R
1 0
wherein Rl, R2, and R3 each denote separately a
llyd-og~l atom, a halogen atom, an alkyl group having from
1 to 3 carbon atoms, or an alkoxy group having from 1 to
6 carbon atoms, X denotes PF6 or BF~, R is a 11YdLUY~1
15 atom, an alkyl group having 1 or 2 carbon atoms or a
phenyl group, at least one of Ri and RS is hydroxyl or
carboxyl and the other is a hydrogen atom, hydroxyl,
carboxyl, an alkyl group having from 1 to 3 carbon atoms,
an alkoxy group having from 1 to 6 carbon atoms, halogen,
2I~7388
12
-S03H or its salt, or -SO2H or its salt, R6 is a hydrogen
atom, an alkyl group having 1 or 2 carbon atoms or a
phenyl group, and wherein the ratio of m to n is from
about 70:30 to about 85:15, preferably from about 75:25
5 to about 81:19, the polymer having an average molecular
weight of from about 2,000 to about 3,000, preferably
from about 2,250 to 2,750, and most preferably about
2,500. Preferably, R is a IIYdLO4~ group and at least
one of Rg and R5 is carboxyl. Specific examples of
10 combinations which may be used include the
hexafluorophosphate or tetrafluoroborate salts of a
conflPnRate between one of 4-diazodiphenylamine or 4-
diazo-4 ' -methoxydiphenylamine, one of benzaldehyde,
acetaldehyde or formaldehyae, and one of a phenol or a
15 benzoic acid. Particularly preferred is the
hexafluorophosphate salt of the polymer of 4-
diazodiphenylamine with formaldehyde and 4-hydroxy
benzoic acid.
Such a diazo resin can be obtained by
20 I-~nA~n~n~ the aromatic diazonium compound and the co-
polymerizable compound with at least one active carbonyl
compound, or with agents producing such a carbonyl
compound, in a strongly acid medium. Particularly useful
rnn~ n~tion media are phn6phnric acid and sulfuric acid,
25 which acids are employed in aqueous solutions of at least
4096 by weight, and preferably 70-100~ by weight.
Particular examples of carrying out the above
13 2~47388
cr~n~pn~tion reaction may by found in, e.g., U.S. Patent
3,867,147, incorporated herein by reference, and are well
known to those skilled in this art.
The dia~o resin is mixed with an oleophilic
5 polymeric binder of high molecular weight . Specif ic
examples of such resins include polymers derived from
hydroxy or carbonyl-containing, ethylenically unsaturated
monomers such as polyacrylates, polymethacrylates,
polyacrylonitriles, polymethacrylonitriles,
lO polyacrylamides, polymethacrylamides, polyacrylic acids,
and polymethacrylic acids or a mixed polymer containing
monomers of two or more of the above resin types, or one
or more of such resins and one or more secondary resins,
e.g., polyesters or polystyrenes. Preferably, the
15 oleophilic binder of the present invention is a high
molecular weight ~at least about 50,000) acrylic co-
polymer including, e.g., a co-polymer of acrylonitrile or
methacrylonitrile and one or more acrylates,
methacrylates or the acids or amides thereof. In a
20 preferred embodiment, such polymers contain the recurring
monomer units having the following general formula (II):
R7 R9 R9
C - C H z - C - ~ j ~ - C H 2 - C - ~ k ( - C H 2 - C~
CN COOQ COOH
wherein R7, R8, and R9 are independently a
hydrogen atom or an alkyl group having from 1 to 3 carbon
25 atoms and R10 is an alkyl group having from 1 to 3 carbon
21~7388
14
atoms or a phenyl group, j is a number from 20 to 30,
preferably about 24, k is a number from 50 to 70,
preferably about 60.5, and l a number from 4 to 14,
preferably about 7, the polymer having an average
molecular weight of from about 50,000 to about 150,000,
preferably from about 55,000 to about 80,000, and most
preferably about 62,000, and having an acid number of
from 20-100, preferably about 50-80, and most preferably
about 60. Preferably R7 and R8 are llydl~g~ atoms, R9 is
methyl and RlO is ethyl. In addition to the above
described three classes of monomers, the preferred
copolymer o:~ the invention may contain additional
amounts, not exceeding about 30%, of other kinds of
monomers co-polymerizable therewith including unsaturated
carboxylic acid amides such as acrylamides or
methacrylamides. A particularly preferred oleophilic
polymeric binder is a co-polymer of 4-hydroxyphenyl
methacrylamide, acrylonitrile, ethylacrylate, and
methacrylic acid in the approximate ratio, respectively,
of 8.5:24:60.5:7.
The copolymerization of the above described
classes of monomers is carried out by a conventional
procedure of radical polymerization in which
predetermined amounts of the individual, ~. are
mixed and dissolved in a suitable organic solvent such as
2-methoxy ethanol or 3-methoxy propanol with admixture of
a radical polymerization initiator such a~ an orçlanic
~1~7388
peroxide, e.g., benzoyl peroxide, and then heated with
agitation. As i8 known in the art, the proportions and
conditions of the polymerization reaction are controlled
so that the optimum amount of polymerization occurs to
achieve molecules of the desired molecular weight and
relative composltion.
The copolymer resin produced by the solution
polymerization discussed above i8 purif ied to remove
unreacted monomers and other impurities, e.g., by
precipitation, and is then ready to be mixed together
with the diazo resin and the other components of the
photosensitive composition.
In accordance with the invention it has been
discovered that by controlling the relative proportion of
the diazo resin, particularly one of formula ~I) to the
binder, particularly one of formula (II), 80 that the
ratio of diazo to binder by weight is from about
0.033/1.0 to about 0.17/1.0, preferably is from about
0.04Z/l.0 to about O.lZ/l.0, and most preferably is from
Z0 about .050/1.0 to about 0.08/1.0, a photosensltive plate
results which is markedly more resistant to alkaline
fountain 601utions and other chemicals than plates
previously produced, e.g., the prior art photosensitive
composition as described in Comparative Example 4.
Z5 To formulate the photosensitive composition of
the present invention 80 that the desired ratio of diazo
resin to binder is achieved, the diazo resin is
21 ~ 7388
~,
16
preferably incorporated into the photosensitive
composition at a concentration by weight of from about
.796 to about 2.4% of the total composition, preferably
from about .85% to about 2.0%, and most preferably from
5 abo7lt 1. 0% to about 1. 4% . The polymeric binder is
preferably incorporated at a concentration by weight of
from about 14.0% to about 21.0% of the total composltion,
preferably from about 16.0% to about 20.0%, and most
preferably from about 17 . 5% to about 19 . 0% .
The photosensitlve composition of the invention
preferably also inc~7l~7~ one or more dyes or pigments for
visualizing images. Examples of such dyes and pigme7 ts
include the following commercially available products:
Crystal Violet (CI 42555), Crystal Violet-carbinol base
(CI 42555:1), Acilan Brilliant Blue 5B (CI 42740),
Victoria Pure Blue BO~ (CI 42595), B0~-20 Blue Dye, Nile
Blue BX (CI 51185) and pigments of other shades and
colors. These dyes or pigments are generally used in an
amount of from about 0.2% to about 1.5% by weight of the
20 photosensitive composition.
An acid such as polyacrylic acid, phosphoric
acid, rh~srh~rous acid, tartaric acid, citric acid, malic
acid, or a salt thereof may optionally be added as a
stabilizer. In a preferred embodiment, a 25% by weight
25 solution of polyacrylic acid 18 in.ol~ol -Led in an amount
of from about 2 to 4g6 by weight of the composition.
~i~738:8
17
In a preferred embodiment, the photosensltive
composition of the instant invention consists essentially
of the previously mentioned ingredients -- i . e., a diazo
resin and binder, dye or pigment and stabilizer,
5 dissolved in a solvent. However, various additional
ingredients, including surface active agents,
plasticizers, fillers and other ~ ~ nts whose function
and particular ingredients are well known in this art,
may also be incorporated into the photosensitive
10 composition if desired for a particular application.
The photosensitive composition of this
invention as described above is dissolved in an
appropriate organic solvent such as 2-methoxy ethanol, 2-
methoxyethyl acetate, propropyleneglycol monomethylether,
15 3-methoxy propanol, 3-methu-Lyy~uyyl acetate,
cyrl nh~- ~n~nP, ethylene d~chloride, or a mixture thereof .
The solvent is preferably 2-methoxy ethanol. The
concentration of the solvent in the prepared
photosensitive coating is from about 60% to 90%,
20 preferably from about 70% to about 80%, and most
preferably from about 75% to about 80% by weight. The
photosensitive composition thus dissolved is then coated
onto an aluminum substrate which has been pretreated as
previously described. Preferably, the photosensitive
25 composition is coated to a thickness of about 0 . 35 g/ m2
to about 1. 86 g~ m2, preferably about 1. 2 g/ m2 (dry
basis ) using one of a number of techniques known in the
21~73~8
18
art, including, for example, by whirler coating, swabbing
or roller application. The coated aluminum substrate is
then dried, preferably at an lnitial temperature a~ about
45 C for about 3 minutes, and then dried at 85 C for
5 about 3 additional minutes.
To develop the photosensitive plate thus
prepared, the plate is exposed to a light source, e.g., a
metal halide, carbon arc or a high-ples~uld mercury vapor
lamp, through a negative and then processed with a
10 developer and gummed up for use, e.g., using an aqueous
solution of 596 gum arabic. Any developer can be used for
removing the non-exposed areas a~ long as it dissolves
the non-e~cposed areas of the photosensitive coating, but
not the cured exposed areas. In particular, a suitable
15 developer for use in developing a photosensitive coating
of the preferred type disclosed herein is a weakly
alkaline aqueous solution comprising an organic solvent,
an alkali agent, and at least one anionic surface active
agent (e.g., an aromatic or aliphatic ~ulphonate) in de-
20 ionized water.
The thus prepared photsensitive printing plateis ready for mounting on a printing press and i8
specially adapted for extended use with an alkaline
fountain ~3olution such as the Advantage Fountain Solution
25 3001 sold by PresAroom Solution Inc., Fort Worth, Tx.
214 7388
19
The following examples illustrate the
invention .
EXAMPLES
Example
An aluminum plate of 1100 Alloy raw coil having
a thickness of 12 gauge ~0.012 in) was degreased and
cleaned by dipping in a mixture of 1% Trisodium Phosphate
and 296 of Sodium Metha Silicate solution at 70*C for 10
seconds .
The aluminum plate was then surface-roughened
by mechanical graining with a 25-30% slurry concentration
oi #Z90 abrasive Sllica material to obtain an optical
density reading between 0 . 23 to 0 . 27 .
Thereafter the aluminum plate was etched with
496 Sodium lIyaroxide solution at 55C for 7.4 seconds.
After washing with water, the aluminum substrate was
neutralized with 12 . 596 of aqueous Nitric Acid solution,
washed with water and then anodized in a 16 . 596 Aqueous
Sulfuric Acid solution to yield an anodic coating weight
of 200 mg per square foot.
After anodizing the aluminum substrate was
dipped in 2.5% aqueous sodium silicate solution at 80C
for 12 seconds, washed with water and dried. Substrate
80 made provided excellent ink-water balance on the
press.
,, 21~7388
A light-sen8itive solution having the following
formulation was applied onto the surface of the
substrate. The amount of the light-sensitive coating
weighed after drying was 1.12g~m2.
Light-Sensitive Coating Solution
r~ , A.rl t Weight ( g )
Methyl Cellosolve 300 gm
PF6 salt of a polymer o~
diphenylamine-4-diazonium salt with
formaldehyde and 4-hydroxy benzoic acid 5 gm
4-hydroxyphenyl methacrylamide-acrylonitrile-
ethylacrylate-methacrylic acid copolymer 75 gm
Polyacrylic acid (25% wgt solution) 10 gm
Victoria Blue BOH 3 gm
The PS plate so prepared was exposed to light
from a 6 KW metal halide lamp at a distance of 71 cm
through a negative film for 24 seconds. The plate was
then developed with a developer having the following
formula and then gummed up to give a lithographic
20 printing plate.
Developer
r~ ellt Weight(9~ _
Phenyl Cellosolve 3 . 75%
Di-Ethanolamine 1. 396
25 Sodium Dibutylnapthalene Sulfonate 1. 2596
Deionized water 93 . 7%
21~73~8
21
The processea plate was mounted on a newspaper
printing press and ran with PSI alkaline fountain
solution. The plate so made provided excellent ink-water
balance and alkaline fountain solution resistance on
5 press. The results are reported below in Table I.
Example 2
An aluminum plate of 1100 Alloy raw coil having
a thickness of 0.30 mm was degreased and cleaned by
dipping in a mixture of 1% Trisodium Phosphate and 296 of
10 Sodium Metha Silicate solution at 70C for 10 seconds.
The aluminum plate was then surface-roughened
by mechanical graining with a 25-30% slurry concentration
of #290 abrasive Silica material to obtain an optical
density reading between 0.23 to 0.27.
Thereafter the ~luminlln plate was etched with
4% Sodium Hydroxide solution at 55C for 7.4 seconds.
After washing with water, the aluminum substrate was
neutralized with 12.5% of aqueous Nitric Acid solution,
washed with water and then anodized in a 16 . 5% Aqueous
20 Sulfuric Acid solution to yield an anodic coating weight
of 200 mg per square foot.
After anodizing, the aluminum substrate was
dipped in a 2.5% aqueous sodium silicate solution at 80C
for 12 seconds, washed with water and dried. The
25 substrate so ma~e provided excellent ink-water balance on
the press.
A light-sensitive solution having the following
formulation was applied onto the surface of the
substrate. The amount of the light-sensitive solution
30 weighed after drying was 1.12 g/m2.
738~
22
Light-Sensitive Coating Solution
C'~ n, ~InPnt ~ Weight(g)
Methyl Cellosolve 300 gm
PF6 salt o~ a polymer of
5diphenylamine-4-diazonium salt with
formaldehyde and 4-hydroxy benzoic acid 3 . 75 gm
5-1-y~lL~,..yl,henyl methacrylamide-acrylonitrile-
ethylacrylate-methacrylic acid copolymer 75 gm
Polyacrylic acid (259~ wgt solution) 10 gm
10Victoria Blue 13OH 3 gm
The PS plate so prepared was exposed to light
from a 6 KW metal halide lamp at a distance of 71 cm
through a negative film for 24 seconds. The plate was
then developed with a developer having the iollowing
15 formula and then gummed up to give a lithographic
printing plate.
Developer -
r)n en t Weiqht ( 96 )
Phenyl Cellosolve 3 . 75%
20 Di-Ethanolamine 1. 3%
Sodium Dibutylnapthalene Suli'onate 1. 25%
Deionized water 93 . 70~6
The processed plate was mounted on a newspaper
printing preYs and ran with PSI alkaline fountain
solution. The plate 80 made provided excellent ink-water
balance but only fairly good resistance toward alkaline
fountain solution. The results are outlined below in
Table I.
Example 3
An aluminum plate of 1100 Alloy raw coil having
a thickness of O . 30 mm was degreased and cleaned by
dipping in a mixture of 196 Trisodium Phosphate and 2% o~
Sodium Metha Silicate solution at 70C for 10 seconds.
88
23
The aluminum plate was then sur~ace-roughened
by mechanical graining with a 25-30% slurry concentration
of ~290 abrasive Silica material to obtain an optical
density reading between 0 . 23 to 0 . 27 .
Thereafter the aluminum plate wa6 etched with
4% Sodium Hydroxide solution at 55 C for 7 . 4 seconds .
After washing with water, the aluminum ~ubs~-~te was
neutralized with 12.5~ of aqueous Nitric Acid solution,
washed with water and then anodized in a 16 . 5% Aqueous
Sulfuric Acid solution to yield an anodic coating weight
of 200 mg per square foot.
After anodizing, the aluminum substrate was
dipped in 2.596 aqueous sodium silicate solution at 80C
for 12 seconds, washed with water and dried. The
substrate so rl~ade provided an excellent ink-water balance
on the press.
A light-sensitive solution having the following
formulation was applied onto the surface of the
substrate. The amount of the light-sensitive solution
weighed after drying was 1. I2 g/m2.
` 2~738~
24
Light-Sensitive Coatin~ Solution
Component Weight ( g )
Methyl Cellosolve 300 gm
PF6 salt of a polymer of
5 diphenylamine-4-diazonium salt with
formaldehyde and 4-hydroxy benzoic acid 2 . 5 gm
4-~-ydlo~y~henyl methacrylamide-acrylonitrile-
ethylacrylate-methacrylic acid copolymer 100 gm
Polyacrylic acid (2596 wt solution) 10 gm
Victoria Blue BOH 3 gm
The PS plate so prepared was exposed to light
from a 6 KW metal halide lamp at a distance of 71 cm
through a negative film for 24 seconds. The plate was
then developed with a developer having the following
15 formula and then gummed up to give a lithographic
printing plate.
Developer
~I "~n nt ~ Weight(
Phenyl Cellosolve 3 . 75%
20 Di-Ethanolamine 1. 3%
Sodium Dibutylnapthalene Sulfonate 1. 25%
Deionized water 93 . 7%
The processed plate was mounted on a newspaper
printing press and ran with PSI alkaline fountain
25 solution. The plate so made provided excellent ink-water
balance, but only fair alkaline resistance on press. The
results are outlined below in Table I.
~1~738~
COMPARATIVE EXAMPLE
Example 4
An aluminum plate of 1100 Alloy raw coil having
a thickness of 0.30 mm was degreased and cleanea by
5 dipping in a mixture of 1% Trisodium Phosphate and 2%
Sodium Netha Silicate solution at 70~C for 10 seconds.
The aluminum plate was then surface-roughened
by mechanical graining with a 25-30% slurry concentration
of #290 abrasive Silica material to obtain an optical
density reading between 0 . 23 to 0 . 27 .
Thereafter the Al ~ plate was etched with
12% Sodium lIydroxide solution at 55C for 7.4 seconds.
After washing with water, the aluminum substrate was
neutralized with 12.596 of aqueous Nitric Acid solution,
15 washed with water and then anodized in a 16 . 5% Aqueous
Sulfuric Acid solution to yield an anodic coating weight
of 200 mg per square foot.
After anodizing the Alllminllm substrate was
dipped in 2.5% aqueous sodium silicate solution at 80C
20 for 12 seconds, washed with water and dried. Substrate
so made provided only fair ink-water balance on the
press .
A light-sensitive solution having the following
formulation was applied onto the surface of the
25 substrate. The amount of the light-sensitive solution
weighed after drying was 1.12 g/m2.
` 214~388
26
Light-Sensitive Coating Solution
C~ L Weight ( g )
Methyl Cellosolve 300 gm
PF6 salt of a polymer of
5diphenylamine-4-diazonium salt with
formaldehyde and 4-hydroxy benzoic acid 2 . 5 gm
4-11ydlu~-y~henyl methacrylamide-acrylonitrile-
ethylacrylate-methacrylic acid copolymer 100 gm
Polyacrylic acid (25% wt solution) 10 gm
Victoria Blue BOE 3 gm
The PS plate 80 prepared was exposed to light
from a 6 KW metal halide lamp at a distance of 71 cm
through a negative film for 24 seconds. The plate was
then developed with a developer having the following
15 formula and then gummed up to give a lithographic
printing plate.
Developer
C~ ^~ t Weight ( % )
Phynyl Cellosolve 3 . 75%
Di-Ethanolamine 1.3%
Sodium Dibutylnapthalene Sulfonate 1. 25%
Deionized water 93 . 7%
The processed plate was mounted on a newspaper
printing press and ran with PSI alkaline fountain
25 solution. The plate 80 made provided only fair ink-water
balance and poor ~ nP resistance on press. The
results are reported below in Table I.
21 ~ 7388
27
TABLE I
Characteri6tic Ex. 1 Ex. 2 Ex. 3 Ex. 4
Ink-Water Balance 5 5 5 3
Alkaline Resistance 5 3 2 0
Note: Table I uses a 0-5 sliding scale in which 5 =
excellent and O = poor.
In view of the above, it will be seen that the
several ob; ects of the invention are achieved and other
advantageous results attained.
As various changes could be made in the above
methods and compositions without departing from the scope
of the invention, it is intended that all matter
contained in the above description shall be interpreted
as illustrative and not in a limiting sense.
