Note: Descriptions are shown in the official language in which they were submitted.
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DEVELOPMENT OF RADIATION SENSITI~E
COMPOSITIONS
This invention relates to the development of
radiation-sensitive compositions and is concerned with
the development of such compositions as are used for
the production of printing plates and photoresists.
In the production of printing plates and
photoresists, a radiation sensitive composition is
coated onto a substrate to form a radiation sensitive
plate which is then image-wise exposed to radiation so
as to selectively expose different areas of the
coating. The radiation struck areas and non-radiation
struck areas have differing solubility in developer
liquids and thus the more soluble areas can be
selectively removed from the substrate by the
application of a suitable developer liquid to leave an
image on the substrate constituted by the less soluble
areas.
Radiation sensitive compositions are usually
classified as being either positive-working or
negative-working. Positive-working compositions have
the property of becoming more soluble in a given
developer liquid when exposed to radiation whereas
negative-working compositions have the property of
becoming less soluble.
This difference has meant that in the past,
the developer liquids used for the two classes of
composition have been substantially different. In
particular, negative-working compositions have
generally required a developer liquid comprising a
substantial proportion of an organic solvent. Thus a
developer liquid suitable for positive-working
compositions would not develop a negative-working
composition and a developer liquid suitable for a
negative-working composition would over develop a
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positive-working composition.
It is an object of the present invention to
provide a developer liquid suitable for use in
developing both positive and negative-working
compositions.
According to one aspect of the present
invention there is provided a method of developing an
image-wise exposed radiation sensitive composition
which comprises the step of contacting the composition
with a developer liquid containing an ethylhexyl
sulphate.
According to another aspect of the present
invention there is provided a developer liquid
comprising, an alkaline material, an ethylhexyl
sulphate, and a surface active agent.
The developer liquid can be used with either
positive-working compositions such as compositions
comprising a quinone diazide and an alkali soluble
resin, compositions comprising a diazo ester and a
novolak resin, and compositions comprising a novolak
ester or negative-working compositions such as
compositions comprising a diazo compound containing
groups having the structure
y
A-N2~ - Ar - R - X - C - X'
in which Ar represents a divalent or other polyvalent
radical derived from an aromatic or heteroaromatic
compound; X and X' which may be the same or different,
each represents O, S or an imino group, provided that
at least one of X and X' is an imino group; Y
represents O or S; R represents a single bond or a
divalent or other polyvalent radical; and A- is an
anion tas described in EP-A-0030862 which is herein
incorporated by reference), compositions comprising at
least one photoinitiator and at least one
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photopolymerisable compound which is an acrylic or
methacrylic ester of a tetra functional polyol having
the general formula:
C(CH2O)4(c3H6O)n H4
wherein the average degree of propoxylation n is from 3
to 6, from 50% to 90% of the available hydroxy groups
have been converted to acrylate or methacrylate groups,
and the remaining hydroxy groups have been reacted with
a di-isocyanate or a polyisocyanate (as described in
EP-A-0260823 which is herein incorporated by
reference), compositions comprising a thioxanthone
sensitiser and a light sensitive polymer having pendant
dimethyl maleimide groups, compositions comprising
supported diazodiphenylamine/formaldehyde condensate,
and compositions comprising trimethylolethane
triacrylate and a methyl methacrylatetmethacrylic acid
copolymer as binder.
The developer liquid is particularly suitable
for use in machines for automatically developing
radiation sensitive plates including such compositions.
Generally, the developer liquid can be used in any
processor designed for developing positive-working
plates. The useful life of the developer liquid will
depend on the manner in which the development section
of the processor is constructed. Processors having
fully enclosed development tanks will give greater bath
life due to restricted contact of the developer liquid
with the atmosphere. The activity of the developer
liquid can be maintained by replenishment and monitored
by determining its conductivity as described in
EP-A-0107454.
The alkaline material is the primary
developing agent for positive-working compositions and
its concentration determines the degree of development
and the useful life of the developer liquid. The
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alkaline material may be a hydroxide, a phosphate an
amine, such as monoethanolamine or a silicate and
preferably is sodium metasilicate. In the latter case,
the sodium metasilicate concentration will generally be
from 4 to 20wjv% preferably from 7 to 12 w/v%.
Suitable hydroxide concentrations are 0.2 to 10 w/v%
(preferably from 2.0 to 5.0 w/v%), suitable phosphate
co~centrations are 4 to 20w/v% (preferably 7 to 12w/v%),
and suitable amine concentrations are 1 to 20 v/v%
(preferably 5 to 10 v/v%).
The ethyl hexyl sulphate acts as a developing
aid for negative working compositions and is preferably
in the form of the sodium salt. However, other salts
may be used. Generallv its concentration will be from
2 to 20% by vol, preferably from 3 to 5% by vol, of a
40w/v% solution.
The surface active agent prevents
overdevelopment of positive working compositions and
may be a non-ionic surfactant such as a polyoxyethylene
lauryl ether or an ethylene oxide/propylene oxide
condensate of polv~ethylene) glycol. The latter is
preferred since it also prevents soiliny deposits being
formed on the plate surface when developing radiation
sensitive plates in some automatic plate processors
using hard water in their plate washing section.
Generally the surface active agent will be present in
an amount of from 0.075% to 1.5% by vol, preferably
from 0.2 to 0.5% by vol.
In an embodiment, the developer additionally
includes a water soluble salt of an aliphatic
carboxylic acid. This may be the potassiurn or sodium
salt of an acid containing 1 9 carbon atoms, preferably
octanoic acid. It acts as a developing aid for both
positive and negative-working compositions. The use of
sodium octanoate is preferred. The water soluble salt
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will generally be present in an amount of from 1% to
20% by vol, preferably from 2% to 6% by vol, of a 40%
w/v solution.
In an embodiment, the developer additionally
includes the sodium salt of ethylene diamine
tetraacetic acid. This has the advantage of complexing
calcium and magnesium ions present in the wash water to
prevent the formation of hard water salts. It will
generally be present in an amount of from .2% to
10.0w/v%, preferably 1 to 3w/v%.
The following Examples illustrate the
invention
EXAMPLE 1
A series of positive-working pre-sensitised
plates consisting of a grained and anodised aluminium
substrate coated with a composition based on a quinone
diazide and an alkali soluble novolak resin were
exposed in a printing down frame beneath a continuous
tone step-wedge.
The plates were then processed in a Howson-
Algraphy Positive Plate Processor containing in the
developer section a developer solution having the
formulation:-
25 Sodium metasilicate 3.5Kg
Brij 30 0.25L
Rewopol NEHS-40 5L
Sodium octanoate
solution (40% w/w) 5L
Nervanaid BConc. 1.0 Kg
Water to 5OL
Rewopol NEHS-40 is a 40% solution of the
sodium salt of 2-ethyl hexyl sulphate tn - ethyl hexyl
sulphate) produced by Rewo Chemicals Ltd, Nervanaid B
Conc is the sodium salt of ethylene diamine tetraacetic
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acid (ABM Chemicals Ltd), and ~rij 30 (I.C.I.) is a
polyoxyethylene lauryl etherO
There was no sign of the plate being over
developed.
EXAMPLE 2
A series of negative-working plates were made
according to Example 1 of European Patent Specification
No.0030862 and were exposed and processed in the same
wa~ as the plate of Example 1. The plates developed
cleanly.
EXAMPLE 3
Example 2 was repeated except that plates made
according to Example 1 of European Patent Specification
No.0260823 were used.
Similar results were obtained.
EXAMPLES 4 TO 6
Examples 1 to 3 were repeated using, as the
developer, the following composition:-
Nervanaid B Conc 0.25 Kg
Sodium metasilicate 3.50 Kg
Sodium octanoate (40%) 2.50L
Rewopol NEHS 40 5.00L
Brij 30 0.25L
Water to 50L
Similar results were obtained in each case.
EXAMPLE 7
Examples 1 to 3 were repeated using as the
developer, the following composition:-
Nervanaid B conc 20Kg
Sodium metasilicate (5H20) 7OKg
Sodium octanoate (40%) 100L
Rewopol NEHS 40 100L
Supronic B10 2L
Demineralised water to 1 OOOLo
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Supronic B10 is an ethylene oxide/propylene
oxide copolymer of poly(ethylene glycol).
Similar results were obtained in each case.
EXAMPLE 8
Examples 1 to 3 were repeated using as the
dev~loper the following composition:-
Nervanaid B conc. 2OKg
Sodium metasilicate (5H2O) 70Kg
Sodium octanoate (40%) 10OL
Rewopol NEHS 40 100L
Supronic B10 0.75L
Demineralised water to 1000L.
Similar results were obtained in each case.
EXAMPLE 9
The following developer formulation was used
in an Autopos automatic plate processor to develop an
image-wise exposed Super Amazon Plate (Howson-
Algraphy) including a positive working radiation
sensitive composition based on a diazo ester and a
novolak resin:-
Sodium Metasilicate 70Kg
Brij 30 5L
Rewopol NEHS40 10OL
Sodium Octanoate (40% sol) 100L
Nervanaid B Conc 2OKg
Demineralised Water to 1000L
The plate developed cleanly with no sign of
over-development.
Similar results were obtained using a Super
Spartan Plate (Howson-Algraphy) and a Triton Plate
(Howson-Algraphy~ which are similarly based on positive
working diazo ester/novolak compositions.
EXAMPLE 10
The above formulation was used to develop
negative-working AQ2 and AQ3 plates ~Howson-Algraphy)
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including radiation sensitive compositions based on a
diazo resin and binder.
The plates developed cleanly with no residual coating.
EXAMPLES 11 to 15
Examples 9 and 10 were repeated using the
following developer formulations:
EX11 EX12 EX13EX14 EX15
Sodium Metasilicate70Kg 40Kg70Kg 70Kg 70Kg
Brij 30 15L 5L 5L 5L 5L
Rewopol NEHS-40100L 100L 50L100L 100L
Sodium Octanoate
(40% sol)100L100L 100L 50L 100L
Nervanaid B Conc20Kg20Kg 20Kg20Kg 40Kg
Demineralised Water to 1000L 1000L 1000L 1000L 1000L
In each case, the plates developed cleanly.
EXAMPLES 16 AND 17
Examples 9 and 10 were repeated using the
following developer formulations:-
EX16 EX17
Sodium Metasilicate 70Kg 70Kg
EX16 EX17
Supronic B10 0.75L 2L
Rewopol NEHS-4010OL 10OL
Sodium Octanoate
t40% sol)100L 100L
Nervanaid B Conc20Kg 20Kg
Demineralised water to 1000 L 1000 L
The plates developed cleanly in each case~
EXAMPLE 17
Example 9 was repeated using commercially
available positive working plates viz New Capricorn
(Horsell) including a radiation sensitive composition
based on novolak ester, P61 (Hoechst) including a
radiation sensitive composition based on a diazo ester
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and novolak resin and Nylolith PMS (BASF) including a
radiation sensitive composition based on a novolak
ester. These plates processed cleanly with no over-
development.
EXAMPLE 18
Example 9 was repeated using Nylolith NL (a
commercially available negative working plate of BASF
including a radiation sensitive composition based on a
supported diazo system). It developed cleanly~
EXAMPLE 19
The developer formulation of Example 9 was
used in an NP60 processor (Horsell) to develop AQ3,
Super Amazon and Super Spartan plates and was used in a
VA6 processor (Hoechst) to develop AQ3 and Super Amazon
plates and an Ultrapos (Horsell) plate including a
radiation sensitive composition based on a novolak
ester. In all cases it was found to develop both
negative and positive plates cleanly.
