Note: Descriptions are shown in the official language in which they were submitted.
i~q ~ 4~9 Xramer Case ~-3
This invention relates to novel polymers and their use
in preparing printing plates. More particularly, this invention
relates to photocross-linkable polymers having pendant diazo ester
groups and printing plates prepared therefrom.
Photocross-linkablé polymers are kn~wn in the art. U.S.
Patent No. 3,467,523, for example, shows polymers containing azido-
sulfonyl groups attached to a polymer chain, which can be used as
light-sensitive substances in printing plates, etc. Unfortunately,
the polymers containing azidosulfonyl groups are limited in that
they require the use of a sensiti~ing agent to render them cross-
linkable at a practical rate with visible or normal ultraviolet
light (without a sensitizer, they require the use of short wave-
length ultraviolet light).
It has now been found that certain polymers containing
pendant diazo ester groups are capable of being photocross-linked
without the use of sensiti~ing agen~s and are excellently suited
for use in the preparation of both lithographic and relief print-
ing plates, as well as for etching resists for printed circuits.
In contrast to many photo~ross-linkable polymer systems, they are
not insensiti~ea by the presence of air. Specifically, the poly-
mers containing pendant diazo ester groups in accordance with
this invention are the polymers that are photocross-linkable
under active radiation and that have the following units
_ _~ p
C=O
C=N2
X
` where P is derived from a soluble hydroxy containing polymer
which has been esterified to ~ive the above pendant groups and X
hyo~^og4n or
isja radical selected from the group consisting of
O O
.. ..
-C-OR, -C-CH3, -CN and -Ar, where Ar is selected from phenyl and
phenyl substituted with 1 to 3 -N02, Cl, F, Br, Cl_8 alkyl or
Cl_s alkyloxy groups and R is selected from C1_18 alkyl, C5_7
- 2 ~
q~
~,¢~
cycloal~yl, Cl ~ alkyl substituted C5_7 cycloalkyl and Ar, where
Ar ls as defined above.
Any soluble hydroxy containing polymer which can be es-
terified to give the desirable pendant groups can be used as the
backbone polymer, providing it contains no functional groups which
react with or decompose diazo groups thermally (e.g., fumarate
esters or sulfonic acids). Typical h~droxyl containing polymers
that can be used in this lnvention are the partly or completely
hydrolyzed vinyl acetate polymers, such as poly(vinyl acetate),
ethylene--vinyl acetate copolymer and vinyl chloride--vinyl
acetate copolymer; vinyl alcohol polymers, such as p~ly(vinyl
alcohol); allyl alcohol copolymers such as styréne--allyl alcohol
copolymer; cellulose and cellulose ethers and esters, such as
cellulose, hydroxyethyl cellulose, ethyl cellulose, hydroxvpropyl
cellulose, ethyl hydroxyethyl cellulosa and hydroxypropyl methyl
cellulose; thermoplastic phenoxy resins, such as the condensa-
tion product of bisphenol A and epichlorohydrin without epoxy
end groups; and polymers and copolymers o hydroxyalkyl acrylates
and methacrylates, such as styrene--hydroxy ethyl acrylate and
poly(hydroxyethyl methacrylate~. Polvmer~ ~hich are ~ater sol-
uble, or soluble in aqueous solutions, such as water-alcohol
mixtures or salt solutions are particularly desirable.
The pol~mers containing pendant diazo ester groups of
this invention can be prepared by several methods which will be
obvious to those skilled in the art. One method, for example,
O .
particularly applicable when X is -C-OR or nitrophenyl is to
partially esterify the hydroxyl containing polymer as follows
o
~P ~ ~ + Cl--C-CH2--X~ ~ P ~^~ + HCl
OH O
C=O
CH2
X
and then to dia~otize the resulting ester as f~llows
P~~~_ + ~ (C2H5)3~ , ~ 3
S2N3 S2MH2
C=O C=O
C, H2 C=N2
X X
Typical of the acid chlorides that may be used to esterify the
hydroxyl containing polymer are ethyl malonyl chloride, phenyl
malonyl chloride, methyl malonyl chloride, 4-nitrophenylacetyl
chloride and 2,4-dinitrophenylacetyl chloride.
Another method of synthesis utilizes the reaction of
the p-toluenesulfonylhydrazone of a carboxylic acid chloride con-
taining an ~-carbonyl group with a hydroxyl containing polymer in
the presence of a strong base.
S02NHNH2
10X--CCOH + ¢~ 502NHNH=CCOH3 ¢~j2NHN=CCCl
CH3 CH3
X (C H5) N
S02NHN=CCCl + ~---- P ~ 2 3 ~ ~,~,_ p __
¢~ O OH o
C=O
CH3 .
C,=N2
X
Typical of carboxylic acids containing an a-carbonyl group which
may be used are glyoxylic acid, benzoylformic acid, 4-methoxy-
benzoylformic acid, 4-methylbenzoylformic acid, and 4-
chlorobenzoylformic acid.
It will be understood that the above preparatory meth-
ods are only illustrative and that other approaches and varia-
tions will be obvious to those skilled in the art. It is desir-
able in most cases to only partially esterify the hydroxyl groups
-- 4 --
of the hydroxyl-containing polymers and thus obtain a polymer
with fewer diazo ester groups. In general, only enough diazo
ester groups to effect cross-linking of the polymer are required.
Most desirably, there will be approximately one diazo ester group
per 1 to 10~ hydroxyl-containing monomer units in the polymer
chain in the case of vinyl and condensation polyrners and approx-
imately one diazo ester group per 0.4 to 25 anhydroglucose units
in the case of cellulose and cellulose derivatives.
Typical of the photocross-linkable polymers containing
pendant diazo ester groups of this invention are the diazoacetyl
ester of the condensation product of bisphenol A and epichloro-
hydrin containing no epoxy end groups, the ethyldiazomalonyl
ester of hydrolyzed ethylene--vinyl acetate copolymer, the phenyl-
diazomalonyl ester of hydrolyzed ethylene--vinyl acetate co-
polymer, the diazoacetyl ester of hydrolyzed ethylene--vinyl
acetate copolymer, the p-nitrophenyldiazoacetyl ester of hydro-
lyzed ethylene--vinyl acetate copolymer, the phenyldiazoacetyl
ester of hydrolyzed ethylene--vinyl acetate copolymer, the
diazoacetyl ester of styrene--allyl alcohol copolymer, the ethyl
; 20 diazomalonyl ester of poly(vinyl alcohol), the 2,4-dinitrophenyl-
diazoacetyl ester of hydroxypropyl cellulose, the methyl diazo-
malonyl ester of ethyl cellulose, the diazoacetyl ester of
methyl acrylate--hydroxyethyl acrylate copolymer, the p-chloro-
phenyldiazoacetyl ester of hydroxypropyl cellulose, the p-
methoxyphenyldiazoacetyl ester of ethyl cellulose, the cyanodi-
azoacetyl ester of hydrolyzed ethylene--vinyl acetate copolymer,
the acetodiazoacetyl ester of hydrolyzed ethylene--vinyl acetate
copolymer, the acetodiazoacetyl ester of poly(vinyl alcohol~, the
o-, m-, and p-tolyldiazoacetyl esters of hydroxypropyl cellulose,
the ethyldiazomalonyl ester of styrene--hydroxypropyl acrylate
copolyrner, the acetodiazoacetyl ester of poly~vinyl alcohol),
the methyldiazomalonyl ester of the condensation product of bis-
phenol A and epichlorohydrin containing no epoxy ond groups, the
acetodiazoacetyl ester of hy~roxyethyl cellulose, the
-- 5 --
p-nitrophenyldiazoacetyl ester of poly(vinyl alcohol), the ethyl
diazomalonyl ester of hydroxypropyl cellulose, the ethyldiazo-
malonyl ester of methyl hydroxypropyl cellulose, the methyldiazo-
malonyl ester of the condensation product of hisphenol A and epi-
chlorohydrin containing no epoxy end groups, the acetodiazoacetyl
ester of methyl methacrylate--hydroxyethyl methacrylate copoly-
mer, the chlorophenyldiazoacetyl ester of poly~vinyl alcohol),
the m-fluorophenyldiazoacetyl ester of hydrolyzed ethylene--vinyl
acetate copolymer, the octyldiazomalonyl ester of poly~vinyl
alcohol), the stearyldiazomalonyl e~ter of poly~vinyl alcohol~,
the p-bromophenyldiazoacetyl ester of hydrolyzed ethylene--vinyl
acetate copolymer, the 4-tert.-butylcyclohexyldiazomalonyl ester
of poly(vinvl alcohol), the 4-methylcycloheptyldiazomalonyl ester
of poly(vinyl alcohol), the cyclopentyldiazomalonyl ester of
hydroxyethyl cellulose, the cyclohexyldiazomalonyl ester of
hydroxyethyl cellulose, the cycloheptyldiazomalonyl ester of
hydroxyethyl cellulose, the p-nitrophenyldiazomalonyl ester of
hydroxyethyl cellulose, the 2,4-dinitrophenyldiazomalonyl ester
of hydroxyethyl cellulose, the 2,4,6-trinitrophenyldiazomalonyl
ester of hydroxyethyl cellulose, the 2,4,6-trichlorophenyldiazo-
malonyl ester of hydroxyathy~ cellulose, the p-tolyldiazomalo~yl
ester of partially hydrolyzed poly~vinyl acetate~, the m-ethyl- :
phenyldiazomalonyl ester of partially hydrolyzed polyCvinyl
acetate), the p-hexy~phenyldiazomalonyl ester of partially
hydrolyzed poly~vinyl acetatel, the p-octylphenyldiazomalonyl
ester of partially hydrolyzed poly(vinyl acetate~, the p-methoxy-
phenyldiazomalonyl ester o~ partially hydrolyzed poly~vinyl
acetate), the m-butyloxyphenyldiazomalonyl ester of partially
hydrolyzed poly(vinyl acetate), the p-amyloxyphenyldiazomalonyl
ester of partially hydrolyzed poly~vinyl acetate) t the p-amyloxy-
phenyldiazoacetyl ester of hydrolyzed ethylene--vinyl acetate
Qn~
copolymer,~the p-octylphenyldia~oacetyl ester of hydrolyzed
ethylene--vinyl acetate copolymer, ~x~
The polymers containing pendant diazo ester groups may
39
be utilized alone or in admixture with other materials~ It may be
desirable in certain cases to extend the dia~o ester containing
polymer with inorganic or organic fillers, including other poly-
mers, with solubility characteristics similar to those of the
photocross-linkable polymer employed. It may also be desirable
to add other compounding ingredients such as plastici~ers, anti-
oxidants, etc., just as long as they do not interfere with the
absorption of light by the polymer and do not cause decomposition
of khe diazo groups. Obviously, there are many cases in which
plasticizers and fillers are not required or desired, and ex-
cellent printing plates can be prepared with the dia~o ester
containing polymer alone.
In practice, the photocross-linkable polymer will gen-
erally be coated on a suitable support. Typical supports that
can be used are grained or ungrained plastic sheets such as poly-
amides, polyesters, polycarbonates and polyolefins; paper and
paper foils; and grained or ungrained metal sheets such as alum-
inum, zinc, copper, iron, steel, silver and gold. Obviously, the
more expensive metals will not normally be used as supports in
printing plates but can be used as a laminate over plastic in
preparing etching resists for printed circuits. By the term
"grainea", used above, is meant a lithographic graining generally
described as a microscopic surface roughness essentially devoid
of scratches. In a~dition to or in place of graining, it will be
understood that the support may be first treated with some mate-
rial, such as described in U.S. Patent 3,440,959 or 3,470,~13,
or Defensive Publication T-868,002, to vary the affinity of the
surface to water or ink. The photocross-linkahle polymer can be
coated on the support by several methods, such as hy compression
molding or solvent casting. By the latter method the photocross-
linkable polymer will be dissolved in a suitable solvent such as
water, alcohol, a halogenated hydrocarbon, ketone~ aromat c, c~e.
and by trailing blade coating, spraying, curtain coating~ dipping,
ctc.~ applied to the support and the solvent allowed to evaporate~
3~
Coatings of various thicknesses can be e~ployed, depending upon
the ultimate utility. For example, if the coated support is to
be used in preparing relief printing pla~es, the thickness of the
light-sensitive coating will be from about ~ mils to about 50
mils. On the other hand, lf the coated support is to be used in
preparing lithographic printing plates, then a thinner light-
sensitive coating of from about 2 microns to about 50 microns
will be used. If the coated support is to be used as an etching
resist for printed circuits, the thickness of the light-sensitive
coating will be from about 0.5 micron to ahout S microns.
The photocross-linkable polymers having pendant diazo
ester groups of this invention can be cross-linked by exposure to
actinic radiation of from about 2000 A to about S000 A. Most
preferably, the light will be from about 3000 A to about ~000 A.
Any of the commercial light sources emitting in this region, such
as mercury vapor ~ights, carbon arc, tungstén filament, etc., can
be used to expose and cross-link the polymers. Various time periods
are required for the exposure, depending upon the specific diazo
ester containing polymer and the intensity of the light. In
general, exposure of from about 3~ seconds to about 30 minutes
will be sufficient to effect cross-linking. After exposure of a
photocross-linkable polyme~ coated support, as for example,
through a negative, the exposed portions will be cross-linked and
insoluble in the usual sol~ent for the polymer, while the unex-
posed portions will be uncross-linked and removable by washing
(i.e., developing) in a solvent for the polymer. The same sol-
vents disclosed above as useful in solvent casting the polymers
on a substrate can be used to wash away unexposed (i.e., uncross-
linked) polymer. In the case of etching resists for printed cir-
cuits, a typical procedure is to expose the photocross-linkable
polymer coating through a negative or some other ~asking means,
wash a~ay uncross-linked polymer to exposë the metal laminate
surface and then etch away the exposed metal.
The following examples are presented for purposes of
-- 8 --
illustration, parts and percentages being by weight unless other-
wise speciied.
Example 1
This example illustrates the preparation of a polymer
containing pe~dant dia~oacetyl groups.
A p-toluenesulfonyl hydraæone of glyoxylic acid is
prepared from 22.7 parts of glyoxylic acid and 46.~ parts of
p-toluenesulfonylhydrazide. After recrystalli~ing from ethyl
acetate-carbon tetrachloride, 20 parts of the hydrazone glyoxylic
acid and 24 part~ thionyl chloirde are refluxed in approximately
100 parts of benzene ~or two hours, after which the volatiles are
removed at aspirator pressure. The residue is triturated with a
small amount of warm benzene, collected and recrystalli~ed from
a mixture of benzene and petroleum ether to yield the p-toluene-
sulfonyl hydrazone of glyoxylic acid chloride, which can he shown
; as follows:
~ CH3
`~ .
S02NHN=CHC--Cl
A solution is prepared containing 7 parts of the p-
toluenesulfonyl hydra~one of glyoxylic acid chloride and 5.7
parts of a phenoxy resin, having the general formula
oCH2--CH-CH2 ~--
CH3 OH
i~ approximately 100 parts of methylene chloride. To the solu-
tion is added drop~ise with stirring in the dark 6.1 parts of tri-
ethylami~e. The reaction mixture is allowed to sta~d in the dark
for three- hours and the~ ~recipitated hy adding to methanol. The
resulting product ~ontains monomer units with the general formula
~ CH2--Ci.H-CH2 ~
CH3
C=O
l=N2
H
The modified resin exhibits strong infrared absorption at 4.75
and 5.9~, showing the presence of ~C=N2 and ~C=0 groups, and
indicating that about 26% of the hydroxyl groups are substituted.
A relief printing plate is prepared by coating a grained
sheet of polyethylene terephthalate with a solution of the dia~o-
acetyl modified resin in methylene chloride and evaporating the
solvent with a stream of nitrogen. The resulting 20 mil coated
; film is covered with a photographic transparency and exposed for
30 minutes to a 450 watt mercury lamp at a distance of approx-
imately 2 inches. The exposed coating is then washed with methylene
chloride to give a sharp high resolution relief image. Similarly,
a 0.5 mil ilm of the diazoacetyl modified resin on a grained
aluminum lithographic plate is prepared, exposed and developed as
described above to give a high resolution image which accepts ink
relative to the aluminum substrate.
Exa~ple 2
This example illustrates the praparation of a polymer
containing dendant ethyldiazomalonyl groups.
To a solution of 3.4 parts of the hydroxypropyl cellu-
lose shown in U.S. Patent 3,27~,521 and having a molar su~stitu--
tion (M.S.) of 3.5 disso~ved in equal parts of tetrahydrofuran
and methylene chloride is added 1.6 parts of pyridine and 3.0
parts of ethylmalonyl chloride with stirring. The reaction mixture
is allowed to stand for two days and then the solids Cpyrid;ne
hydrochloride) removed by filtration. The solvent is stripped
from the filtrate at reduced pressure, the product is redissolved
in tetrahydrofuran ahd reprecipitated by pouring into water at
-- 10 --
3~
60C. ApproxLmately 75% of the hydroxyl groups of the hydroxy-
propyl cellulose are esterified.
To a solution of 2.8 parts of the above ethylmalonyl
derivative of the hydroxypropyl cellulose in methylene chloride
is added 1 part triethylamine and 2 parts of p-toluenesulfonyl
azide. The solution is allowed to stand in the dark for two days
and the solvent removed under vacuum. The residue is dissolved
i~ tetrahydrofuran and reprecipitated by pouring into water at
60C. The resulting product exhibits a strong infrared absorption
N
at 4.7~ showing the presence of -C- groups.
A relief printing plate is prepared by coating a grained
sheet of polyethylene terephthalate with a solution of the ethyl-
diazomalonyl modified cellulose in methylene chloride and evap-
orating the solvent with a stream of nitrogen. The resulting 5
mil coated fil~ is covered with a photographic transparency and
exposed for 20 minutes to a 450 watt medium pressure mercury
lamp at a distance of approximately 2 inches. The exposed coat-
ing is then washed with methylene chloride to give a sharp relief
image.
Exampl-e 3
This example illustrates the preparation of another
polymer containing pendant ethyldiazomalonyl groups.
An ethyle~e--vinyl acetate copolymer, containing approx-
imately 28 weight percent of groups derived from vinyl acetate,
is saponified to yield a copolymer having the general formula
~--(CH2--CH2) ~8--CH-CH2 ~
OH
To a mixture of 2.6 parts of the saponified copolymer and 88 parts
of benzene is added 1.5 parts of ethylmalonyl chloride and the
mixture heated at reflux for 1.5 hours during which time all the
solids go into solution. To the resulting solution is aaded 1.1
parts of 2,6-lutidine and tha mixture heated at reflux. After 2
hours the refluxing mixture is filtered hot and the filtrate
poured with stirring into 316 parts of methanol. The precipitate
is collected and washed with methanol. The resulting ethyl mal-
onate modified copolymer exhibits a strong infrared absorption
at 5.75~ and has monomer units with the general formula
.,(CH2--CH2) ~,8-CI H--CH2--
o
C=O
ICH2
IC=O
o
C2H5
To a solution o 1.8 parts of the ethyl malonate modified copoly-
mer in methylene chloride is added 0.5 part of triethylamine and
l 0 part of p-toluenesulfonylazide. The mixture is allowed to
stand at room temperature in the dark for two days and then the
product is precipitated by pouriny it into about 150 parts of
methanol. The precipitatea product is collected and washed with
methanol. The resulting ethyl dia~omalonate modified copolymer
exhibits strong infrared absorption at 4.7~ and 5.75~ and has
structural units with the general formula
v~ ~(cH2-cH2)~8--CIH CH2 ~~~--~~~~~
O
C=O
C=N2
C=O
C2H5
A relief printing plate is prepared by coating a grained
sheet of polyethylene terephthalate with a lO~ solution of the
ethyl diazomalonate modified copol~mer in toluene and drying in
a stream of nitrogen, The resulting lO mil coated film is covered
with a photographic negative and exposea 15 minutes to a 450 watt
mercury lamp at a distance of 2 inches. The exposed film is then
~ ~4~'~3~
washed with methylene chloride to give a high resolution image in
which the half-tone dots are claarly visible.
~xample 4
This e~ample lllustrates the preparation of a polymer
containing pendant acetodia~oacetyl groups.
To a suspensio~ of 2,~ parts of the saponified copolymer
described in Example 3 in 44 parts of benzene is added 2.5 parts
of diketene dissolved in an equal amount of acetone. The mixture
is heated on a steam bath for 5 minutes and poured with stirring
into approximately 400 parts of methanol. The precipitate is
collected and washed with methanol. The resulting acetoacetate
modified copolymer is dia~oti~ed using triethylamine and p-
toluenesulfonylazide by the method described in Example 3. The
resulting diazoacetoacetate modified copolymer exhibits strong
infrared absorption at 4.7~ and 5.8~ and has structural units
with the general formula
_v~ (cH~-cH2~8--lH CH2--~~'~
I
C=O
l=N2
C=O
C~
A ~ solution of the dia~oacetoacetate modified polymer
in methylene chloride is coated on a grained sheet of polyethylene
terephthalate, and the solvent evaporated to give a coated thick-
ness of 8 mils. The film is covered with a photographic trans-
parency and exposed to a 450 watt mercury lamp for 30 minutes.
The exposed coating is washed with methylene chlorid~ to give a
well defined relief lmage.
Example 5
This example illustrates the preparation of a polymer
containing pendant p-nitropheny~diazoacetate groups.
To a suspension of 2.6 parts of the saponified copolymer
described in Example 3 in 44 parts of ben~ene is- added 2 parts
- 13 -
1(J~9~39
of p-nitrophenylacetyl chloride. The mixture is heated at reflux
for 3 hours and 0.8 part of pyridine added. After standing at
room temperature for an hour, the reaction mixture is poured into
240 parts of methanol. The precipitate is collected and washed
with methanol.
To a solution of 2 parts of the p-nitrophenylacetate
modified polymer in 98 parts of dry pyridine, cooled in an ice
bath, is added 0.4 part of piperidine and 1.0 part of p-toluene-
sulfonylazide with stirring. The solution is stored in the dark
overnight and then poured into 31~ parts of methanol. The bright
yellow preaipitate is collected and washed with methanol. The
resulting p-nitrophenyldiazoacetate modified copolymer exhibits
strong infrared absorption at 4.8~, 6.6~ and 7.S~ and has
structural units with the general formula
_~A~ (CH2--CH2)~8-IH CH2
O ~ ':
C=O
=N 2
[~
N02
A relief printing plate is prepared by coating a grained
sheet of polyethylene terephthalate wïth a solution of the p-
nitrophenyldiazoacetate modified copolymer in methylene chloride
and evaporating the solvent with a stream of nitrogen. The re-
sulting 5 mil coated film is covered with a photographic negativeand exposed to a 450 watt meraury lamp a~ a distance of 2 inches.
T~ exposed' coating i5 then washad with toluene to give a good
raised image. Exceptionally high resolution of the half-tone
dots is noted.
Example 6
To a suspension o 3.0 parts of the saponified copoly-
mer described in Example 3 and 50 parts of ben~ene is added ~.4
parts of phenylmalonyl chloride and 1.0 part o pyridine. The
- 14 -
~0~9439
mixture is heated at reflu~ for l.S hours and allowed to cool to
room temperature. The reaction mixture is poured into 300 parts
of methanol and the precipitated polymer collected and washed
with methanol. To a solution of 2.1 parts of the phenyl malonate
modified copolymer in methylene chloride is added 0.5 part tri-
ethylamine and 1.0 part o p-toluenesulfonylazide. The mixture
is allowed to stand at room temperature in the dark for 2 days,
and the polymer precipitated by pouring into 200 parts of meth-
anol. After washing with methanol, the polymer exhibits strong
infrared absorption at 4.7~.
A lithographic plate is prepared by whirl coating a 5%
solution of the phenyldiazomalonate modified copolymer in chloro-
form onto a brush grained aluminum plate. After drying at room
temperature, the plate is covered with a photographic negative
containing line work and half-tone pictures, and exposed to a bank
of four meraury arcs rated as 80 watts/linear inch. The exposed
film is washed with chloroform to give a good image. The plate
was rubbed with gum arabic solutions and gave excellent prints when
used on an offset lithographic press.
EXam~le 7
To a solution of 11.0 parts of poly~vinyl alcohol~,
having a molecular weight of approximately 96,000, in 20Q parts of
N-methyl pyrrolidone is added 18.9 parts of ethylmalonyl chloride
and 5.0 parts of acetyl chloride with stirring. The reaction mix~
ture is poured into ~000 parts o water to precipitate the poly-
mer. The solids are collected and washed with water.
To a solution o 17.8 parts of the ethyl malonate mod-
ified polymer in 310 parts of acetonitrile is added successively
8.1 parts of triethylamine and 15.7 parts of p-toluenesulfonyl-
azide. The solution is stored in the dark for two days, and poured
into 2500 parts of water. The solids are collected, taken up in
27~ parts of acetonitril~ and reprecipitated. The infrared spec-
trum has a band at 4.7~ indlcating the presence o~ dia~o ester
groups.
- 15 -
~ 1~9439
A 5% (wt./vol.~ solution of the above ethyl diazomal-
onate polymer in chloroorm is whirl coated on a 6-mil grained
aluminum plate, dried at room temperature, and exposed for two
minutes through a photographic negative and a Stauffer 21 Step
Sensitivity Guide (AT 20 x 0.15) to a bank of four medium pres-
sure mercury arcs rated at 80 watts/linear inch. The plate is
washed with acetone to yield a sharp image and a solid coating
at step 5 on the guide. The plate is rubbed successively with
gum arabic solution, commércial fountain solution (3 oz./gal.),
and commercial lithographic rub up ink. The image areas accept
the ink while the substrate aluminum does not.
Example 8
To a solution of 8.8 parts o~ the polytvinyl alcohol),
96,000 mol wt., described in Example 7, in lS0 parts of N-methyl
pyrrolidone is added 7.8 parts of acetyl chloride and 20.0 parts
of p-nitrophenylacetyl chloride with stirring. The solution is
allowed to stand for ~4 hours, and is poured into 4000 parts of
water. The precipitate is collected and washed with water.
To a solution of 2.9 parts of the p-nitrophenyl acetate
modified polymer in 145 parts of dry pyridine is added 0.9 part
of piperidine and 2.0 parts of p-toluenesulfonyl a~ide. The
solution is kept in the dark overnight and poured with stirring
into 465 parts of methanol. The yellow precipitate i5 collected,
chopped, and washed with methanol. The infrarad spectrum of the
dried polymer shows strong absorption at 4.8~
A solution of the p-nitrophenyldiazoacetate modified
polymer in chloroorm is whirl coated on a 6 mil grained aluminum
plate and dried at room temperature in the dark to give a film
approximately 5~ thick. The film is exposed through a phbto-
graphic negati~e to the light from a 650 watt quart~-halogen tung-
sten lamp at a distance of 1~ inches. The plate i`s washed gently
with chloroform. An orange image remains in the areas exposed to
the light, while the bac~ground dissolves, exposing the aluminum
substrate. The pla~e is rubbed with 14 Baume gum arabic
- 16 -
~ Oq9~,9
solution and then with commercial lithographic rub up ink. The
image areas accept the ink while the substrate aluminum does not.
- 17 -
