Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
6~
sACKGROUND OF THE INVENTION
The present invention relates to a resin which may be
used in the production of photosensitive elements and which
renders such photosensitive elements developable by aqueous
developers. The invention further relates to a radiation-
sensitive composition which may be employed to produce an
improved photographic element such as a lithographic printing
plate. Such plates show an increase of stability and press run
life and can be developed without organic solvents. The
composition can be readily formed into adherent coatings useful
in the graphic arts especially in the production of lithographic
printing plates.
Although there are many resins known which may be used
in the production of photosensitive elements in general, the
majority of them are severely limited by the need to develop the
photosensitive elements with solutions containing substantial
amounts of organic solvents. Such developing solutions are
undesirable in that their effluent is toxic and environmentally
harmful and the solvents are costly.
It is known to prepare interpolymers for the
stabilization of formaldehyde solutions wherein the interpolymer
is composed of vinyl acetate, vinyl acetal and vinyl alcohol,
as shown in IJnited States Patent 4,085,079. Similar polymers
are also disclosed in United States Patent 2,179,051. Each of
these resins, though, when used in photosensitive elements,
must be developed with developers which contain organic solvents.
What is desired, therefore, is a resin which may be
used to produce a photosensitive element which is developable
with a solution which does not necessarily contain organic
~76~
solvents and need only contain minor amounts of salts and
surfactants. Such resin should allow the photosensitive element
to develop in a dissolving fashion, thereby substantially
eliminating the presence of particles which may be re-deposited
onto the element surface and in-terfere with the operation
of the element. Such resin should also allow the production of
a photosensitive element having superior sensitivity, image
resolution, run length, and post-exposure and post development
image contrast, and which is compatible with commonly used
printing plate and press processing solutions.
SUMMARY OF THE INVENTION
.
This invention relates to a resin which may be used in
the production of a photosensitive element. More particularly,
this invention relates to a resin comprising units of each of
the general types A, s and C, in an ordered or random sequence,
wherein A is present in an amount of from 5% to 20% by weight
and is a unit of the formula
-CH -CH-
C = O
CH3
B is present in an amount of from 4% to 30% by weight
and is a unit of the formula
-CH2-CH-
OH
~ Z~$~
and C is present in an amount of from 50% to 91~ by weight and
comprises ~nits of each of the formulae C I, C II and C III
/C~2\
-CH OEI- -CH C~ CH-
O O (C I), 1 O (C II), O (C III)
~ / \/ I
CH CH H-C-R
R R
-CH-
where R is lower alkyl or hydrogen, and wherein said un:its C I
are present in an amount of from 7S~ to 85%; units C II are
present in an amount of from 3~ to 5%; and units C III are
present in an amount of from 10% to 22%, based on the total
weight of the units C.
ccording to another aspect, the invention relates to
a photosensitive composition which comprises, as a binder, a
resin as defined above and a photosensitive diazonium salt
condensation product.
DETAILED DESCRIPTION OF THE INVENTION
As used in describing the resin of this invention, the
term "lower alkyl" refers to a straight or branched chain
hydrocarbon having from 1 to 8 carbon atoms and containing no
unsaturation.
The vinyl alcohol/vinyl acetate copolymers useful as
a starting material for the production of the resin of this
invention are those having from about 75~ to about 80~
hydrolization by weight and, preferably, an average molecular
weight (AMW) of from about 5,000 to about 100,000. As used in
-- 3 --
~ ~t7~ 4~
this application hydrolization is on a weight basis and not a
mole basis. Such copolymers are easily synthesized by methods
known to those skilled in the art, or are commercially available.
Suitable copolymers include Vinol* 523 (AMW - 70,000) and Vinol 205
(AMW = 26,000) available from Air products Co. of Allentown,
Pennsylvania; Elvanol* 52-22 (A~W - 72,000) available from
DuPont of Wilmington, Delaware; and Gelvatol* 20-30 (AMW - 10,000),
Gelvatol 20-60 (AMW - 60,000), and Gelvatol 2~-90 ~AMW - 90,000)
available from Monsanto Co. of St. Louis, Missouri.
The particular copolymer chosen as the starting material
depends upon the end use desired for the resin. For instance,
if the resin is to be used in the production of a lithographic
printing plate, the copolymers are preferably those having
higher molecular weights (i.e. about 50,000 to about 100,000). If
the resin is to be used in the production of screens for screen
printing applications, the copolymers are preferably those having
lower molecular weights (i.e. about 5,000 to about 30,000).
Although these ranges are generally preferred, they are not
critical.
In forming the resin of this invention, the copolymer is
first dissolved in a solvent mixture of water and a hydroxyl group
containing solvent. The hydroxyl group-containing solvent must
be miscible with water, it must be a solvent for the copolymer,
and it must be a solvent for the final resin product. Preferably,
the hydroxyl group containing solven~ is an aliphatic alcohol.
Most preferably, the alcohol is one having from about 1 to 4 carbon
atoms such as ethanol. In order to ensure that the copolymer
* Trade Mark - 4 -
7~r~
molecules of the starting material are not so intertwined with
each other nor having tertiary or quaternary structure to the
extent that the reaction is interfered with to a substantial
degree.
The invention provides a method of preparing the
foregoing resin. The process steps include first dissolving the
vinyl alcohol/vinyl acetate copolymer in a solvent mixture of
water and a hydroxyl-group containing solvent to form a reaction
solution. This is usually conducted for at least about 12 hours
at a temperature of from about 20C to the boiling point of the
solution depending on the molecular weight of the copolymer. The
solution is then adjusted to at least about 50C while adding a
catalytic amount, preferably from about 1.0% to about 1.5% by
weight of an acid. ~his is insufficient to cause hydrolization.
Titrated into the acidified mixture is an aliphatic aldehyde
over a period of several hours. The aldehyde is added in an
amount sufficient to produce a degree of acetal formation of
from about 50% to about 91% by weight. Preferably one vigorously
mixes said reaction mixture throughout the foregoing steps.
Preferably the acid is then removed from the mixture by evaporation
or the mixture is neutralized.
The preferred aldehyde is acetaldehyde or propionalde-
hyde. The particular aldehyde chosen may also be related to the
end use intended for the resin of this invention. E'or use in the
production of a lithographic printing plate, propionaldehyde
is preferred; for use in the production of a screen printing
screen, acetaldehyde is preferred, The amount of aldehyde
titrated into the reaction mixture is preferably from about 25%
to about 100~ by weight of the copolymer. More preferably the
-- 5 --
amount of the aldeh~de is from about 28% to about 67~ by weight
of the copolymer.
As the acetal groups are formed at the expense of the
hydroxyl content of the copolymer, the water solubility is
reduced. In order to prevent premature precipitation of the
product formed, additional amounts of the hydroxyl group
containing solvent used in the solvent mixture are added
simultaneously with the aldehyde to accommodate the product's
reduced water solubility and increasing solvent solubility.
In order to properly form the acetal groups, a catalytic
amount of an acid is required to be present during the
titrations. Preferably the acid used is an inorganic mineral
acid or an organic sul~onic acid. Suitable mineral inorganic
acids include hydrochloric acid, sulfuric acid and phosphoric
acid. Suitable organic sulfonic acids include p-toluene
sulfonic acid and stilbene disulfonic acid. Most preferably,
the acid catalyst is hydrochloric acid.
After the titrations are completed, the reaction
mixture preferably is neutralized with an alkaline salt in order
to quench the reaction mixture so as to prevent the deacetaliz-
ation which may otherwise occur. The neutralization shouldadjust the pEI of the reaction mixture to about 6.5 to about 7.5,
and should preferably be 7Ø Suitable alkaline salts for the
neutralization include sodium carbonate, potassium carbonate,
sodium hydroxide and potassium hydroxide, with sodium carbonate
being the most preferred.
After neutralization, the reaction mixture is preferably,
although not necessarily, cooled to room temperature (about 22 to
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~.276~?4(~
25C) and then slowly mixed with water or other suitable
compositions such as acetone or methyl ethyl ketone with
continued vigorous agita-tion to effect precipitation. The
resulting precipitates is water washed to remove all remaining
acid, aldehyde and unreacted copolymer, and is then warm air
dried so as to have not more than 1% water residue.
The resultant resin, when used to form a photosensitive
element, is found to be developable with a solution which does
not necessarily contain organic solvents and need only contain
a minor amount, if any, of salts and surfactants; it allows the
photosensitive element to develop in a dissolving fashion,
thereby substantially eliminating the presence of particles which
may be re-deposited and interfe~e with the operation of the
element; allows the production of a photosensitive element having
superior sensitivity, image resolution, run length and post-
exposure and post-development image contrast; and is compatible
with commonly used plate and press processing solutions.
A photosensitive composition which may be prepared
using the resin of this invention comprises, for example, an
admixture of a diazonium salt, and, if desired, a photo-
polymerizable monomer and a photoinitiator; and the resin of
this invention. The mixture is usually prepared in a solvent
composition which is compatible with all the composition
ingredients. Suitahle solvents for this purpose include water,
tetrahydrofuran, butyrolactone, glycol ethers such as
propylene glycol monomethyl ether and methyl cellosolve,
alcohols such as ethanol and n-propanol, and ketones such as
methyl ethyl ketone, or mixtures thereof. Preferably, the
-- 7 --
solvent comprises a mixture of tetrahydrofuran, propylene
glycol monomethyl ether and butyrolacetone. The composition is
then coated on the substrate and the solvent removed by drying.
The composition may also contain other art recognized ingredients
such as colorants, acid stabilizers, plasticizers and exposure
indicators in amounts easily determined by those ski]led in the
art.
Specific examples of light sensitive diazonium
materials useful as aforementioned include any suitable light
sensitive diazonium polymeric or monomeric compound which are
well known to the skilled artisan, although the polymeric
diazonium compounds are preferred. Suitable diazonium compounds
include those condensed with formaldehyde such as disclosed in
United States 2,063,631 and 2,667,415, the polycondensation
products such as disclosed in United States 3,849,392 and
3,867,147, and the high photo-speed and co-condens~d diazos
such as disclose~ in United States 4,436,804 and United States
4,533,620.
Preferably, the polymeric binder is present in the
photosensitive composition at a percent solids level of
from about 20% to about 75P~ by weight. A more preferred range
is from about 30% to about 65% by weight and, most preferably, the
polymeric binder is present at a percent solids level of -from
about 35% to about 50% by weight. A preferred light sensitive
diazonium salt condensation product is prepared by reacting at
least one A-N2X compound and at least one Bl compound of the
formula
E( C a b)m
-- 8 --
in which A is a radical of a compound of the formula
(Rl-R3-) pR2 N2X
wherein
Rl is an optionally substituted phenyl or naphthyl
group,
R2 is an optionally substituted phenylene group r
R3 is a single bond or one of the groups
2 q 4
-O- (CH2) r-NR4-
-S- (CH2) r-NR4-,
-S-CHz-CO-NR4-~
5
--O--,
-S- or
-CO-NR4-
wherein
q is a number from 0 to 5,
r is a number from 2 to 5,
R4 is selected from the group consisting of hydrogen~
alkyl with 1 to 5 carbon atoms, aralkyl with 7 to 12 carbon atoms,
and aryl with 6 to 12 carbon atoms,
R5 is an arylene group having 6 to 12 carbon atoms,
X is an anion
p is a number from 1 to 3,
E is a radical obtained by splitting off of m
H atoms from a compound free of diazonium groups
selected from the group consisting of aromatic amines,
~ ~:'7~
phenols, thiophenols, phenyl ethers, aromatic thioethers,
aromatic heterocyclic compounds, aromatic hydrocarbons and
organic acid amides,
Ra is selected from the group consisting of hydrogen
and phenyl,
Rb is selected from the group consisting of hydrogen, alkyl,
lower acyl and phenyl, and
m is an integer from 1 to 10
in a strongly acidic condensation medium under condensation
conditions sufficient to produce a polycondensation product of
an aromatic diazonium compound containing, on the average, about
0.] to 50 Bl units per unit of A-N2X.
Preferably, this diazonium salt embodiment comprises
the 1:1 polycondensation product of 3-methoxy-4-diazo-diphenyl
amine sulfate and 4,4'-bis-methoxy-methyl-diphenyl ether,
precipitated as the mesitylene sulfonate, such as is taught in
United States 3,849,392.
The diazonium salt is preferably present in the
composition of the subject invention at a percent solids level of
from about 3% to about 20% by weight. More preferably it is
present at about 5% to about 18% by weight and most preferably
the diaæonium salt is present at a percent solids level of from
about10% to about 15% by weight.
A particular photosensitive composition further
includes an acrylic monomer. When a photopolymerizable
composition such as this is being employed, a suitable photo-
initiator is usually also present. Suitable photoinitiators
which may be used in this invention are preferably those free-
-- 10 --
.276Q~8
radical photoinitiators having a maximum absorption range of fromabout 320 to about 400 nm. Examples include the acetophenones,
benzophenones, triazines, benzoins, benzoin ethers, xanthones,
thioxanthones, acridenes and benæoquinones. More preferred of
these are the 2-aryl-4,6-bis-trichloromethyl-triazines.
The most preferred photoinitiator is 2-stilbenyl
4,6-di(trichloromethyl)triazine.
The photoinitiator is preferably present in the
composition at a percent solids level of about 1.5% to about
8.0% or more by weight, more preferably about 2.0~ to about
6.0% ~y weight and is most preferably present at a percent solids
level of from about 3.0~ to about 4. 06 by weight~
According to a particular embodiment, the photopoly-
merizable mixture of the subject invention comprises a
polyfunctional acrylic monomer which has two or more unsaturated
groups and a urethane oligomer which is hereinafter described.
The polyfunctional monomer is capable of reacting with
the urethane oligomer upon exposure to imaging radiation. The
monomer is characterized as having the unsaturated groups being
acrylic or methacrylic acid esters. The preferred monomer is
either a solid or liquid having a viscosity of greater than about
700 cps at 25C, preferably greater than about 2000 cps at 25C.
Most preferably, the monomer has a viscosity of greater than
about 4000 cps at 25C. A preferred polyfunctional monomer is an
ethylenically unsaturated compound having from 2 to 6 acrylic
or methacrylic acid ester groups.
Examples of compounds which are suitable for use as the
monomer of this invention include trimethylol propane tri(meth)-
acrylate and the ethoxylated or propoxylated analogs thereof,
pentaerythritol triacrylate, pentaerythritol trimethacrylate,
dipentaerythritol monohydroxy penta(meth)acrylate, dipentaery-
thritol hexaacrylate, dipentaerythritol hexamethacrylate,
pentaerythritol tetracrylate and pentaerythritol tetramethacryl-
ate. Preferably, the monomer is dipentaerythritol monohydroxy
pentaacrylate, although a combination of suitable JnOnOmerS is also
advantageous.
The monomer is present at a percent solids level which
is preEerably in the range of from about 10% to about 35~ by
weight. More preferably, the monomer is present at a percent
solids level of from about 15~ to about 30~ by weight and most
preferably from about 1~ to about 25% by weight. The oligomeric
component of the photopolymerizable mixture of the composition of
the subject inven~ion is a photocurable oligomer or polymer which
i5 prepared by reacting one molar equivalent of a substantially
linear polymeric compound having an active hydrogen group at each
end thereof with at least two molar equivalents of a diisocyanate
compound so as to form a prepolymer having an isocyanate group at
each end thereof; and subsequently reacting said prepolymer with
at least two equivalents of an ethylenically unsaturated compound
having an active hydrogen group to provide said prepolymer with
unsaturation at each end thereof. The preferred oligomer is one
having a polyester backbone prepared from an aliphatic dicarboxy-
lic acid and an aliphatic diol. The preferred dicarboxylic acid
is linear and has from about 2 -to 8 carbon atoms. The polyester
is prepared in such a way that the compound is symmetrical and
hydroxy-terminated. A procedure for doing so would be known to
~;~7~
the skilled artisan, for example as shown in Sandler and Karo,
POlymer Synthesis, Vol. 2, Academic Press 1977, pp 140-167. The
polyester polyol is in turn reacted with preferably an aliphatic
diisocyanate having from 2 to 15 carbon atoms, more preferably
withacycloaliphatic diisocyanate. The diisocyanate is reacted
with the polyester polyol so that one of the two isocyanate
groups is reacted with the terminal hydroxy group on the end of
the polyester backbone. The remaining isocyanate group is
subsequently reacted with a hydroxy~containing acrylate or
methacrylate. For example, 1,6-hexane diol is reacted with
adipic acid in a mole ratio of greater than 1:1 (adipic acid/1,6-
hexane diol) to form a polyester and then reacted with
dicyclohexyl-methane-4,4' bis diisocyanate in a 2:1 mole ratio
(diisocyanate/polyester). The product is reacted with 2-
hydroxy ethyl acrylate in a 2:1 mole ratio (acrylate/diisocyanate-
polyester product) to form an oligomer useful in this invention.
The oligomer may be characterized as follows:
U-D-R -D-U
wherein:
Rl is the radical of an essentially linear polymeric
compound having two end groups with active hydrogen functionality,
D is the radical of a diisocyanate compound, and
U is the radical of a compound having ethylenic
unsaturation and a group with an active hydrogen.
Examples o~ compounds which can be used as the Rl
group are polyesters obtained by reacting a dicarboxylic acid
with a diol in such a fashion that the mole ratio of diol to
dicarboxylic acid is greater than 1:1 so as to have a symmetrical
~ 2~7~
hydroxyl terminated polymer; polyethers obtained by reacting a
diol with an alkylene oxide in such a fashion that the mole
ratio of diol to alkylene oxide is greater than 1:1 so as to have
a symmetrical hydroxyl terminated polymer; and epoxies obtained
by reacting a symmetrical diglycidyl compound with a diol in
such a fashion that the mole ratio of diol to diglycidyl
compound is greater than 1:1 so as to have a symmetrical
hydroxyl terminated polymer.
More specifically, Rl groups which are polyesters are
prepared from dicarboxylic acids such as oxalic, malonic, succinic,
glutaric, adipic, pimelic, suberic, azelaic and sebacic acids,
and from diols such as ethylene glycol, diethylene glycol,
neopentyl glycol, propylene glycol, dipropylene glycol, 1,3-
butane diol, 1,4-butane diol, 1,6-hexanediol and 2-ethyl-1, 6-
hexane diol.
Rl groups which are polyethers are prepared from
diols such as ethylene glycol, diethylene glycol, propylene
glycol, dipropylene glycol, neopentyl glycol, 1,3-butane diol,
1,4-butane diol, 1,6-hexane diol and 2-ethyl-1,6-hexane diol,
and alkylene oxides such as ethylene oxide, propylene oxide and
tetrahydrofuran.
Rl groups which are epoxies are prepared ~rom diols
such as ethylene glycol, diethylene glycol, propylene glycol,
dipropylene glycol, neopentyl glycol, 1,3-butane diol, 1,4-butane
diol, 1,6-hexane diol and 2-ethyl-1,6-hexane diol, and diglycidyls
such as diglycidyl isophthalate, diglycidyl terephthalate,
diglycidyl phthalate and bisphenol-A diglycidyl ether.
Examples of compounds which can be used as the D group
are ethylene diisocyanate, propylene diisocyanate, tetramethylene
diisocyanate, dicyclohexyl-methane-4,4'-diisocyanate, hexamethy-
lene diisocyanate, l-methyl-2,3-diisocyanatocyclohexane,
l-methyl-2,6-diisocyanatocyclohexane, lysine diisocyanate,
4,4'-ethylene-bis-(cyclohexyl isocyanate) and isophorone
diisocyanate.
Example of compounds which may be used as the U group
include hydroxyethyl acrylate, hydroxypropyl methacrylate,
hydroxypropyl acrylate, hydro~yethyl methacrylate, 1,3-butane diol
acrylate, 1,3-butane diol methacrylate, 2,4-butane diol
acrylate, 1,4-butane diol methacrylate, neopentyl glycol
acrylate, neopentyl glycol methacrylate, pentaerythritol
triacrylate, pentaerythritol trimethacrylate and the mono acrylate
and ~ethacrylate of polyethylene glycol, polypropylene glycol and
polycopolymers of ethylene glycol and propylene glycol.
Useful oligomers in the practice of this invention
include those oligomers preferably having a molecular weight of
from about 1500 to about 4000, more preferably from about 2000 to
about 3500 and, most preferably, the oligomer has a molecular
weight of about 3000. It is desirable that the oligomer be in
solid form or semi-solid form, i.e. having a viscosity of
greater than about 480,000 cps at 25C. The composition
preferably contains the oligomer at a percent solids level of
from about 10~ to about 35% by weight. ~ore preferably the
oligomer is present in the radiation polymerizable composition
of this invention in an amount of from about 15% to about 30%
by weight and it is most preferably present at a percent solids
level of from about 15% to about 25% by weight. A fuller
description of such oligomers appears in EP-A 184725
- 15 -
~.~7~ 8
One o~ the significant aspects of this em~odiment of the
invention is the fact ~hat the unique combination of photo~
initiator, diazonium salt and photopolymerizable mixture
eliminates the need for use of an oxygen barrier layer or the
necessity for processing in a nitrogen barrier environment,
although the e~act mechanism for this is unclear. Among the
advantages derived is elimination of 1) the inconvenience of
applying a second coating, 2) the concern over the refractive
index and solubility of the oxygen barrier layer, 3) the concern
over bllnding on a printing press due to residue from the oxygen
barrier layer, and 4) the concern over potential image gain due
to the oxygen barrier layer.
~ he photoacti~ator which may be included in the
composition of this invention should be an amine-containing
photoactivator which combines synexgistically with the free-
radical photoinitiator in order to extend the effective half-life
of the photoinitiator, which is normally in the approximate range
of about 10 9 to 10 15 seconds. Suitable photoactivators include
2-(N-butoxy) ethyl-4-dimethylamino benzoate, 2-(dimethylamino)
amino benzoate and acrylated amines. Preferably the photo-
activator is ethyl-4-dimethylamino benzoate. The photoacti~ator
is preerably present in the composi~ion of this invention in an
amount of from about 1.0% to about ~.0% by weight, although the
skilled artisan may use more ox less as desired.
Accordin~ to another particular embodiment, the
photopolymerizable mixture of the subject invention comprises
a polyfunctional acrylic monomer which has two or more
- 16 -
~ 27~
unsaturated groups and a monofunctional acrylic monomer which
has 1 unsaturated group.
The polyfunctional acrylic monomer is described
above.
The monofunctional monomer is an ethylenically
unsaturated compound having one unsaturated group. The mono-
functional monomer is characterized as having the unsaturated
group being an acrylic or methacrylic acid ester. Preferably,
; the monofunctional monomer is a liquid having a viscosity in
the range of from about 1 to about 25 cps at 25C.
Examples of compounds which are suitable for use as
the monofunctional monomer of this invention include tri-
methylol propane mono(meth)acrylate and the ethoxylated or
propoxylated analogs t~ereof, pentaerythritol(meth)acrylate,
tetrahydro furfuryl(meth)acrylate, cyclohexyl acrylate, cyclo~
hexyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate,
glycidyl acrylate and glycidyl methacrylate. Preferably, the
monomer is pentaerythritol acrylate, although a combination of
suitable monomers is also advantageous.
In the photopolymerizable mixture of these two mono-
mers the polyfunctional monomer should be present in an amount
of more than about 50% and, more preferably, should be present
in an amount of from about 65% to about 99%, most preferably
from about ~0% to about 97.5~. The monofunctional monomer
should comprise the balance of the photopolymerizable mixture.
The photopo]ymerizable mi~ture is present at a
percent solids level which is preferably in -the range of from
about 20~ to about 70~ by weight. More preferably, the
- 17 -
~1.27~i~?4,~3
photopolymerizable mixture is present at a percent solids level
of from about 30~ to about 60% by weight and most preferably about
30% to about 50% by weight.
One of the significant aspects of this embodiment of the
invention is that the 3-dimensional structure provided by the
polyfunctional monomer provides good matrix integrity allowing for
a tough image and the linear propagation provided by the mono-
functional monomer provides good photospeed.
This embodiment, too, reduces the need for use of an oxygen
barrier layer or the necessity for processing in a nitrogen
barrier environment.
One of the significant aspects of this invention is that the
photosensitive composition produced thereby may be developed
with a composition which does not necessarily con-tain any organic
solvents and which need only contain a minor amount o salts
and surfactants. There is a great advantage in the elimination
of organic solvents in the developer composition due to the fact
that such solvents are expensive and their effluents are toxic.
Other components which may be included in the photosensitive
composition of this invention include acid stabilizers, exposure
indicators, plasticizers, photoactivator5 and colorants.
Suitable acid stabilizers useful within the context of this
invention include phosphoric, citric, benzoic, m-nitro benzoic,
p(p-anilino phenylazo) benzene sulfonic acid, ~,~'-dinitro-2,2'-
stilbene disul~onic, itaconic, tartaric and p-toluene sulfonic
acid, and mixtures thereof. Preferably, the acid stabilizer is
phosphoric acid. When used, the acid stabilizer is preferably
present in the radiation-polymerizable composition in the amount
- 18 -
~1 27~ 8
of from about 0.3% to about 2.0%, and most preferably from about0.75% to about 1.5%, although the skilled artisan may use more or
less as desired.
Exposure indicators (or photoimagers) which may be useful
in conjunction with the present invention include
4-phenylaæodiphenylamine, eosin, azobenzene/ Calcozine Fuchine
dyes and Crystal Violet and Methylene Blue dyes. Preferably, the
exposure indicator is 4-phenylazodiphenylamine. The e~posure
indicator, when one is used, is preferably present in the
composition in an amount of from about 0.001% to about 0.0035~
by weight. ~ more preferred range is from about 0.002% to about
0.030~ and, most preferably, the exposure indicator is present in
an amount of from about 0.005~ to about 0.20~; although the
skilled artisan may u~e more or less as desired.
A plasticizer may also be included in the composition of
this invention to prevent coating brittleness and to keep the
composition pliable if desired. Suitable plasticizers include
dibutylphthalate, triarylphosphate and substituted analogs
thereof and, preferably, dioctylphthalate. The plasticizer is
preferably present in the composition of this invention in an
amount of from about 0.5~ to about 1.25~ by weiyht, although
the skilled artisan may use more or less as desired.
Colorants useful herein include dyes such as Rhodamine,
Calcozine, Victoria Blue and Methyl violet, and such pigments as
the anthraquinone and phthalocyanine types. Generally, the
colorant is present in the form of a pigment dispersion which may
comprise a mixture of one or more pigments and/or one or more
dyes dispersed in a suitable solvent or mixture of solvents.
-- 19 --
When a colorant is used, it is preferably present in the
composition of this invention in an amount of from about 1.5% to
about 4.0% by weight, more preferably from about 1.75~ to about
3.0% and most preferably from about 2.0% to about 2.75%, although
the skilled artisan may use more or less as desired.
The composition of this invention may be dispersed or
dissolved in a solvent to facilitate application of the
composition to the substrate. Suitable solvents for this purpose
include water, tetrahydrofuran, butyrolactone, glycol ethers
such as propylene glycol monomethyl ekher and methyl cellosolve,
alcohols such as ethanol and n-propanol, and ketones such as
methyl ethyl ketone, or mixtures thereof. Preferably, the solvent
comprises a mixture of tetrahydrofuran, propylene glycol
monomethyl ether and butyrolactone. In general, the solvent
system is evaporated from the coating composition once it is
applied to an appropriate substrate, however, some insignificant
amount of solvent may remain as residue.
Substrates useful for coating with the composition of this
invention to form a lithographic printing plate include sheets o~
transparent films such as polyester, aluminum and its alloys and
other metals, silicon and similar materials which are well known
in the art. Preferably, the substrate comprises aluminum. The
substrate may irst be pretreated by standard graining and/or
etching and/or anodizing techniques as are well known in the art,
and also may or ma~ not have been treated with a composition such
as polyvinyl phosphonic acid, sodium silicate or the like
suitable for use as a hydrophilizing agent.
In the production of photographic elements such as lithogra-
phic printing plates, an aluminum substrate is first preferably
- 20 -
~ ~2'76a~
grained by art recognized methods such as by means of a wire
brush, a slurry of particulates or by chemical or electrochemical
means, for example in an electrolyte solution comprising
hydrochloric acid~ The grained plate is preferably then anodized
for example in sulfuric or phosphoric acid in a manner well
known in the art. The grained and optionally anodized surface
is preferably then rendered hydrophilic, for example, by
treatment with polyvinyl phosphonic acid, sodium silicate or the
like by means which are also known to the skilled artisan. The
thusly prepared plate is then coated with the composition of
the present invention, preferably at a coating weight of from
about 0.6g/m2 to about 2~5g/m2, more preferabl~ from about 0.8g/m~
to about 2.0g/m2 and most preferably from about 1.2g/m2 to about
1 5g/m2, although these coating wei~hts are not critical to the
practice of this invention, and dried.
Preferably the thusly prepared lithographic printing plate is
exposed to actinic radiation through a negative. The exposed
plate is then developed with a suitable aqueous developer
composition such as an aqueous developer comprising one or more
0 o~ the following groups:
a) a sodium, potassium or lithium salt of octyl, decyl
or dodecyl monosulfate;
b) a sodium, lithium, potassium or ammonium metasilicate
salt; and
c) a lithium, potassium, sodium or ammonium borate salt;and
d) an aliphatic dicarboxylic acid, or sodium, potassium
or ammonium salt thereof having from 2 to 6 carbon atoms;
and
e) mono,di-, or tri-sodium or -potassium phosphate.
- 21 -
20731-940
Other suitable developers include water, benzoic acid or
sodium, lithium and potassium benzoates and the hydroxy substitutea
analogs thereof as well as those developers described in United
States Patent 4,43G,807.
In conventional use, the developed plate is finished
with a subtractive finisher such as a hydrophilic polymer. Examples
include cold water soluble dextrin and/or polyvinyl pyrrolidone,
a nonionic surfactant, a humectant, an inorganic salt and water,
as taught by United States 4,213,887.
For the purpose of improving the press performance of a
plate prepared as described above, it is known that baking of the
exposed and developed plate can result in an increase in the
number of quality impressions over that otherwise obtainable. To
properly bake the plate, it is first treated with a solution desig-
nated to prevent loss of hydrophilicity of the background during
baking. An example of an effective solution is disclosed in United
States 4,355,096. The thusly prepared plate is then heat treated
by baking at a temperature of from about 180C up to the annealing
temperature of the substrate, most preferably about 240C. The
effective baking time is inversely proportional to the temperature
and averages in the range of from about 2 to about 15 minutes. At
240C the time is about 7 minutes.
Example 1
75.0 g of Vinol 523, a vinyl alcohol/vinyl acetate copo-
lymer which has from about 75~ to 80~ hydroxyl groups by weight and
an average molecular weight of about 70,000, is dissolved in a
- 22 -
~ 2~
solution comprising 225.0 g of water and 200.0 g of ethanol
for 16 hours at 70C after which 10.13 g of hydrochloric acid
(37%) is added and the temperature adjusted to 60C while
mixing vigorously. 37.66 g of propionaldehyde is slowly
titrated into the reaction mixture. Simultaneously, 250.0 g of
ethanol is likewise titrated into the reaction mixture. The
mixture i~ then neutralized to a pH of 7.0 with a sodium
carbonate/sodium hydroxide (50/50) mixture. The product is
isolated in granular form by precipitation with water. It is
then dried so as to have a moisture residue of not greater than
1.0%. A yield of 107 g or about 96% is obtained. The average
molecular weight is about 90, ono.
Using stanaard analytical techniques the product is found
to consist of 13.6% acetate, 9.8% hydroxyl and 76.6~ aceta~
groups. Of the acetal groups, 80% are found to be six-membered
cyclic acetal, 4% are five-membered cyclic acetal, and 16% are
intermolecular acetals.
Example 2
40.0 g of Gelvatol 20-30, a vinyl alcohol/vinyl acetate
copolymer which has from about 75% to 80% hydroxyl groups by
weight and an average molecular weight of about 10,000, is
dissolved in a solution comprising 120.0 g of water and 120.0 g
of ethanol for 16 hours at 70C after which 10.13 g of
hydrochloric acid (37%) are added and the temperature is adjusted
to 60C while mixing vigorously. 12.06 g of acetaldehyde is
slowly titrated into the reaction mixture. Simultaneously, 120.0
g of ethanol is likewise titrated into the reaction mixture.
The mixture is then neutrali~ed to a pH of 7.0 with a sodium
- 23 -
carbonate/sodium hydroxide (50/50) mixture. The product is
isolated in granular form by precipitation with water. It is
then dried so as to have a moisture residue of not greater than
1.0%. A yield of 49.5 g or about 95% is obtained. The average
molecular weight is about 10,500.
Using standard analytical techniques the product is found
to consist of 17.0% acetate, 28.0% hydroxyl and 55.0% acetal
groups. Of the acetal groups, 80% are found to be six-memberecl
cyclic acetal, 4% are five-membered cyclic acetal, and 16% are
intermolecular acetals.
Example 3
40.0 g of Gelvatol 20-30, is dissolved in a solution
comprising 120.0 g of water and 120.0 g of ethanol for 16 hours
at 70C after which 10.13 g of hydrochloric a-id (37%) are added
and the temperature is adjusted to 60C while mixing vigorously.
27.41 g of hexanal is slowly titrated into the reaction mixture.
Simultaneously, 120.0 g of ethanol is likewise titrated into
the reaction mi~ture. The mixture is then neutralized to a pH
of 7.0 with a sodium carbonate/sodium hydroxide (50/50) mixture.
The product is isolated in granular form by precipitation with
water. It is then dried so as to have a moisture residue of not
greater than 1.0~. A yield of 64.9 g or about 95% is obtained-
Using standard analytical techniques the product is foundto consist o~ 17.0% acetate,9.0~ hydroxyl and 74.0% acetal groups.
Of the acetal groups, 80% are Eound to be six-membered cyclic acetal,
4% are ~ive-membered cyclic aceta~, and 16% are intermolecular
acetals.
- 24 -
~ ~7~
Example 4
40.0 g of Gelvatol 20-30, is dissolved in a solution
comprising 120.0 g of water and 120.0 g of ethanol ~or 16 hours
at 70C after which 10.13 g of hydrochloric acid (37%) are added
and the temperature is adjusted to 60C while mixing vigorously.
35.98 g of octanal is slowly titrated into the reaction mixture.
Simultan~ously, 120.0 g of ethanol is likewise titrated into the
reaction mixture. The mixture is then neutralized to a pH of
7.0 with a sodium carbonate/sodium hydroxide (50/50) mixture.
~he product is isolated in granular form by precipitation with
water. It is then dried so as to have a moisture residue of
not greater than 1.0%. A yield of 72.5 g or about 95% is
obtained. The average molecular weight is about 11,200.
Using standard analytical techniques the product is found
to consist of 17.0% acetate, 10.0% hydroxyl and 73.0% acetal
groups. Of the acetal groups, 80% are found to be six membered
cyclic acetal, 4% are five-membered cyclic acetal, and 16% are
intermolecular acetals.
Example 5 (Comparison~
A sample of Formvar 12/85, a polyvinyl acetal resin
obtained from Monsanto Corporation of St. Louis, Missouri which
has been prepared according to United States Patent 2,179,~51
is analyzed using standard analytical techniques whereby the
product is found to have an average molecular weight of 32,000
and to consist of 23.5~ acetate, 5.7~ hydroxyl and 70.8% acetal
groups. Of the acetal groups, 90-95% are found to be six-
membered cyclic acetals, 0% are five-membered cyclic acetals and
5-10~ are intermolecular acetals.
- 25 -
, ~ ~
~ 2~
Example 6 (Comparison)
A sample of Butvar B-90, a polyvinyl butyral resin obtained
from Monsan-to Corporation of St. Louis, Missouri which has been
prepared according to United States Patent 2,915,58~ is analyzed
using s-tandard analytical -techniques whereby the product is Pound
to have an average molecular weight of 41,000 and to consist of
1~ acetate, 19~ hydroxyl and 80~ acetal groups. Of the acetal
groups, 90-95% are fo~nd to be six-membered cyclic acetals, 0
are five-membered cyclic acetals and 5-10~ are intermolecular
acetals.
Example 7
Various properties o~ a resin prepared as in Example 1 are
compared with those ofFormYar*12/85, as described in Example 5
and Butvar B-90, as described in Example 6. The results are
tabulated in Table I. The procedures employed are standard
ASTM ana}ytical techniques as shown, unless indicated.
Table I
ASTM Inventive Formvar Butvar
Units Method Resin 12/85 ~-90
Tensile 3
Strength 10 psi D638-58T 12.5-16.36.5-7.5 7.0-8.0
Elon~ation % D638-58T 85 30 75
Glass
Temperature C D1043-51(1) 57-71 92-100 62-68
Dielectric 103 ohm D150-59T 2.7 3.1 3.0
Constant 106 ohm D150-59T 2.5 2.9 2.8
Viscosity cps (2) 2~00-3000500-600 ~,000-18,000
Speci~ic
Gravity - D792-50 1.227 1.219 1.100
. 26 -
*Trade Mark
(1) The glass transition temperatur~ was determined by ASTM
D1043~Sl and by Differential Scanning Calorimetry. Results by
Differential Scanning Calorimeter run 5 to 8C higher than
ASTM method.
t2) Viscosity was determined in 15~ by weight solutions in
toluene: ethanol (60:40) at 25C using a Brookfield ~iscometer.
It can be readily seen that the resin of this
invention shows substantially increased tensile strength and
elongation while maintaining similar glass transition temperature,
dielectric constant and specific gravity. Viscosity
variations are not significant since they are essentially a
function of molecular weight.
Example 8
40O0 g of Gelvatal 20-~0, a vinyl alcohol/vinyl acetate
copolymer which has from about 75% to 80% hydroxyl groups by weight
and an average molecular weight of about 60,000 is dissolved in a
solution comprising 120.0 g of water and 120~0 g of ethanol
for 16 hours at 70C after which 10.13 g of hydrochloric acid
(37%) are added and the temperature is adjusted to 60C while
mixing vigorously with 27.41 g of hexanal.
Using standard analytical techniques the product is
found to consist of 1502% acetate, 7.6% hydroxyl and 77.2~
acetal groups. Of the acetal groups, ~0% are found to be six-
membered cyclic acetal, 4% are five-membered cyclic acetal,
and 16% are intermolecular acetals.
Example 9
75.0 g of Elvanol 52-22, a vinyl alcohol/vinyl acetate
copolymer which has from about 75% to 80% hydroxyl groups by
weight and an average molecular weight of about 90,000, is
- 27 -
7~
dissolved in a solution comprising 225.0 g of water and 200.0 g
of ethanol for 16 hours at 70C after which 10.13 g of
hydrochloric acid (37%) is added and the temperature adjusted
to 60C while mixing vigorously with 28.62 g of acetaldehyde.
Using standard analytical teehniques the product
is found to consist of 17O2% aeetate, 13.6% hydroxyl and 69.2%
aeetal groups. Of the aeetal groups~ 80% are found to be six-
membered eyclic acetal, 4% are five-membered cyclie aeetal, and
16% are intermoleeular aeetals.
Example 10
40.0 g of Vinol 205, a vinyl alcohol/vinyl acetate
copolymer which has from about 75% to 80% hydroxyl groups and
an average molecular weight of about 26,000, is dissolved in
a solution comprising 120.0 g of water and 120.0 g of ethanol for
16 hours at 70C after which 10.13 g of hydrochloric acid (37%)
are added and the temperature is adjusted to 60C while mixing
;~ vigorously with 20.09 g of propionaldehyde.
Using standard analytical techniques the produet is
found to eonsist of 13.6% acetate, 9.8% hydroxyl and 76.6%
aeetal groups. Of the acetal groups, 80% are found to be six-
membered eyelic aeetal, 4~ are five-membered eyclic acetal, and
16% are intermoleeular aeetals.
Example 11
An 8" x 25" seetion of lithographie grade 1100
aluminum alloy is degreased with an aqueous alkaline degreasing
solution and eleetroehemieally grained using 900 coulombs of
alternating current in a medium of nitric aeid and aluminum
nitrate. The grained plate is well rinsed and anodized in a
sulfuric acid bath. Sufficient eurrent and voltage is used to
~ 2~ -
~v27~ gL8
produce an oxide layer of 2.8g/m2. The anodized plate is well
rinsed and hydrophilized by immexsin~ the plate into a solution
of polyvinyl phosphonic acid. The plate is well rinsed and dried.
The thusly prepared plate is whirler coated with a solution having
the following composition:
~ w/w
Binder Resin as described in Example l4.36
Polycondensation product of 3-methoxy-
diphenyl amine-4-diazonium sulfate and
4,4-bis-methoxy methyl diphenyl ether,
isolated as the mesitylene sulfonate 4.59
Phosphoric Acid 0.23
4-Phenylazodiphenylamine 0.09
Pigment Dispersion 6.57
Propylene glycol monomethyl ether 74.08
Butyrolactone 10.08
The coated and dried plate is exposed to actinic
radiation through a negative exposure flat so as to yield a solid
seven on a 21 step Stouffer step wedge. The plate is developed
using the following composition at a pH o 7.3:
% w/w
sodium benzoate 6.9
sodium octyl sulfate 3~0
trisodium phosphate 2.8
monosodium phosphate 1.5
2 Balance
and finished with the following composition:
% w/w
Dextrin*** 5.52
sodium octyl sulfate 1.61
Triton X-100**** 1.00
- 29 -
~R~P~ RJ~
~.27~
% W/W
G.ivgaurd DXN***** 0.05
H3PO~ 2.37
H2O Balance
________
*** hydrolyzed tapioca dextrin
**** isooctyl phenol polyoxyethylene ethanol; 4.5 moles
ethylene oxide
***** 1,4-dimethyl-6-acetoxy-dioxane and run on a Solna
sheet fed press using abrasive ink, over-packing, and
a Dahlgren dampening system until image breakdown is
achieved. Under these conditions the plate provides
103,000 acceptable impressions.
Example 12
An aluminum plate selected and pretreated as in
Example 11 is whirler coated with a solution having the following
composition: % w/w
Binder Resin as described i.n Example 8 3.72
Polycond.ensation product as in Example 11 3.72
Phosphoric Acid 0.37
Dye 0.19
Propylene glycol monomethyl ether76.60
Butyrolactone 18.40
The coated and dried plate is exposed to actinic
radiation throuyh a negative exposure flat so as to yield a solid
seven on a 21 step Stou~fer step wedge. The plate is developed
and finished as described in Example 11.
- 30 -
Under the conditions of Example ll the plate provides
llO,000 acceptable impressions.
Example 13
An aluminum plate prepared as in Example 11 is whirler
coated with a solution having the following composition:
% w/w
Binder Resin as described in Example 94.19
Polycondensation product as in Example 11 4.41
Phosphoric Acid 0.51
Pigment Dispersion 4.42
4-Phenylazodiphenylamine 0.013
Solvent System 90.00
where.in the solvent system is comprised of 95% of a mixture
of n-propanol and water (72:28) and 5% of butyrolactone.
The coated and dried plate is exposed to actinic
radiation through a negative exposure flat so as to yield a
solid seven on a 21 step Stouffer step wedge~ The plate is
developed and finished as described in Example 11.
Under the conditions of Example 11 the plate provides
125,000 acceptabl.e impressions.
Example 14
An aluminum plate prepared as in Example 11 is whirler
coated with a solution ha~ing the following composition:
% w/w
Binder Resin as described in Example 10 8.0
Polycondensation product as in Example ll 10.0
Phosphoric Acid 2.0
4-Phenylazodiphenylamine 0.05
Pigment Dispersion 9.0
4~
% W/W
Propylene glycol monomethyl ether 35.48
Butyrolactone 35.48
The coated and dried plate is exposed to actinic radiation
through a negative exposure flat so as to yield a solid seven
on a 21 step Stouffer step wedge. The plate is developed and
finished as described in Example 11.
Under the conditions of Example 11 the plate provides
70,000 acceptable impressions.
Example 15
An aluminum plate prepared as in Example 11 is whirler
coated with a solution having the following composi-tion:
~_ w/w
Binder Resin as described in Example 2 5.48
Co-condensation product of diphenyl
amine-4-diazonium sulfate and 2,5-
dimethoxy-4-(tolyl mercapto)benzene
diazonium tetrachlorozincate with
paraformaldehyde 3.47
Phosphoric Acid 0.23
4-Phenylazodiphenylamine 0.09
Pigment Dispersion 6.57
Propylene glycol monomethvl ether74.08
Butyrolactone 10.08
The coated and dried plate is exposed to actinic
radiation through a negative exposure flat so as to yield a
solid seven on a Stouffer Step Wedge.
- 32 -
~.2~ 463
The pla~e is de~eloped with tap water and is found to be
fully developed and fully desensitized~ It is then ~inished
with ~he composition stated in ~xample 11.
Under the conditions of Example 11 the plate provides
95,000 acceptable impressions.
It can be readily observed that plates prepared
according to -this invention show substantially increased press
runs yet may be developed with compositions that do not
necessarily contain organic solvents and need only contain a
minor amount of salts and surfactants.
An aluminum plate as described in Example 11 is whirler
coated with a solution having the following composition:
w/w
Binder resin as described in Example 1 4.54
Dipentaerythritol monohydroxy pentaacrylate 2.01
Diacrylated urethane oligomer formed by
reacting 1,6-hexane diol with adipic acid
in a mole ratio o~ greater than 1:1 (adipic
acid/1,6-hexane diol) to form a polyester
20and then reacting with dicyclohexyl-
methane-41~'-bis diisocyanate in a 2:1 mole
ratio (diisocyanate/polyester). The product
is then reacted with 2-hydroxy ethyl
acrylate in a 2:1 mole ratio (acrylate/diiso-
cyanate polyester product) 2.01
Polycondensation product
as in Example 11 1.22
2-Stilbenyl-4,6-dl(trichloromethyl)triazine 0.32
.s' ~,~, .
- 3 3 -
% w/w
Methyl cellosolve 89.90
The coated and dried plate is exposed to actinic radiation
through a neqative exposure flat so as to yield a solid seven
on a 21 s-tep Stouffer step wedge. ~he plate is developed
and finished as described in ~xample 11.
Under the conditions of Example 11 the plate provides
595,000 acceptable impreqsions,
Example 17
A lithographic printing plate is prepared and processed
as described in Example 16 excep~ that the diacrylated ~rethane
oligomer i5 omitted. Under these conditions the plate providas
only 315,000 acceptable impressions.
Example~
A lithographic printing plate is prepared and processed
as described in Example 16 except that the dipentaerythritol
monohydroxy pentaacrylate is omitted. Under these conditions
the pla-te provides only 340,000 acceptable impressions.
Example 19
A lithographic printing plate is prepared and
processed as descri~ed in Example 16 except that the diazo
composition is omitted. Under these conditions the plate
provides only 220,000 acceptable impressions.
Example 20
A }ithographic printing plate is prepared and processed
as described in Example 16 except that the 2-stilbenyl-4,6-di-
(trichloromethyl)triazine is omitted. Under these conditions the
plate provide~ only 335,000 acceptable impressions.
- 34 -
- - \
It can be readily observed that plates prepared according
to this invention IExample 16) show substantially increased press
runs and may be developed with compositions which do not contain
organic solvents.
Example 21
An aluminum plate as described in Example 11 is whirler
c~a-ted with a solution having the following composition:
% w/w
Binder resin as described in Example 9 4.54
10 Pentaerythritol tetraacrylate2.01
Diacrylated urethane oligomer as in Example 16 2.01
Polyconaensa~ion product as in Example 11 1.22
2-Stilbenyl-~,6-di(trichloromethyl~triazine 0.32
Methyl cellosolve 89.90
The coated and dried plate is exposed to actinic
radiation through a negative exposure flat so as to yield a
solid seven on a 21 step Stouffer step wedge. The plate is
developed and finished as described in Example 11.
Under the conditions of Example 11 the plate provides
605,000 acceptable impressions.
Example 22
A~ aluminum plate as in Example 11 is whirler coated
with a soluti.on havin~ the following composition:
w/w
~inder resin as descr~.bed in Example 84.54
Pentaerythritol tetraacrylate 2.01
Diacrylated urethane oligomer as described
in Example 16 2.01
~ 35 -
~ w/w
Polycondensation product as described in Example 11 1.22
2-Stilbenyl-4,6-di(trichloromethyl)triazine 0.32
Methyl cellosolve _ _
The coated ana dried plate is exposed to actinic
radiation through a negative exposure flat so as to yield seven
on a 21 s-tep Stouffer step wedge. The plate is de~eloped and
finished as described in Example 11.
Under the conditions of Example 11 ~he plate provides
10 515, 000 acceptable impressions.
Exam~le ?3 ~Comparison)
An aluminum plate as in Example 11 is whirler coated
; with a solution having the followin~ composition:
% w~w
Binder resin Formvar 12/85,(see Example 6J 4.54
Pentaerythritol~tetraacrylate 2.01
; Diacrylated urethane oligomer as described in
Example 16 2.01
Polycondensation product as in Example 11 1.22
20 2-Stilbenyl-4,6-di(trichloromethyl)triazine0.32
Methyl cellosolve
The coated and dried plate is exposed to actinic
radiation through a negative exposure flat so as to yield a
solid seven on a 21 step Stouffer step wedge. The plate is
attempted to be developed with the developer described in
Example 11.
- 36 -
!~
\
~.2~
It is found that ~he plate cannot be de~eloped. No
indication of coating removal or de~ensitiza-tion is detected.
Example 24
An alumlnum plate as in Example 11 i9 whirler coated
with a solut~on ha~ing the following composition:
~ w~w
Binder resln as de~cribed in Example 1 4.54
Pentaerythritol tetraacrylate 2.85
Pentaerythritol triacrylate 0.86
10 Pentaerythritol diacrylate 0.19
Pentaerythritol acrylate 0.12
Polycondensation product as in Example 11 1.22
2-Stilbenyl-4,6-di(trichloromethyl)triazine 0.32
Methyl cellosolve Balance
The coated and dried plate i5 exposed to actinic
radiation through a ne~ative exposure flat so as to yield a solid
seven on a 21 step Stouffer step wedge. The plate is developed
and finished as described in Example 11.
Under the c~nditions of Example 11 the plate provides
540,000 acceptable impressions.
Example_25
A lithographic printing plate ~s prepared and
processed as described in Example 24 except that the
pentaerythritol acrylate is omitted. Under these conditlons
the plake provides only 315,~00 acceptable impressions.
? ~
, .:
- 37 -
Example 26
A lithographic printinq plate is prepared and
processed as described in Example 2~ except that the 2~stilben~yl-
4,6-di-(trichloromethyl)triazine is om:itted. Vnder ~hese
conditions the plate provides only 335,000 acceptable
impressions.
~xa~ple 27
An aluminu~ plate as described i.n Example 11 is whirler
coa-ted with a solution havinq the following composition:
1 0 ~ w/w
~inder resin as described in Example 8 4.54
Pentaerythrito1 tetraacrylate 2.~5
Pentaerykhritol triacrylate 0.86
Pentaerythritol diacrylate D.l9
Pentaerythritol acrylate 0.12
Polycondensation product as in Example 11 1.22
2-Stilbenyl 4,6-di(trichloromethyl)triazine 0.32
Methyl cellosolve Balance
The coated and dried pla e is exposed to actinic
radiation through a negative expos~lre ~lat so as to yield a
solid seven on a 21 step Stouf~er step wedge. The plate is
developed and ~inished as described in Example 11.
Under the conditio~s of Example 11 the plate provides
510,000 acceptable impressions.
Example 28
An aluminum plate as in ~xample 11 is whirler coated
with a solution having the following composition:
- 38 -
% w/w
Binder resin as described in Example ~ 4.54
Pentaerythritol tetraacrylate 2.85
Pentaerythritol triacrylate 0.86
Pentaerythritol diacrylate 0.19
Pentaerythritol acrylate ~.12
Polycondensation product as described in Example 11 1.22
2-Stilbenyl-4,6-di(trichloromethyl)triazine 0.32
Methyl cellosolve Balance
i~ The coated and dried plate is exposed to actinic
radiation through a negati~e exposure flat so as to yield a
solid seven on a 21 step Stouffer step wedge. The plate is
developed and finished as described in Example 11.
Under the conditions of Example 11 the plate
provides 575,000 acceptable impressions.
- 39 -
