Note: Descriptions are shown in the official language in which they were submitted.
~079561 `-
This invention relates to radiation pol~merlsable
composition~.
B~gian Patent ~lo.82,Q~404 describes ~hoto-
polymerisa~e c~mpositions comprising ta) a wa~er-
soluble or~water-dispersible.polymer or copolymer, or-.
a po~ymer or copolymer mixture in which one or more of the
components is water-soluble or wa~er-dispersi~le; tb) an
addition-polymerisable monomer whlch is soluble in or
compatible with a solvent or dispexsing medium or (a); ana.
(c) a photo-initiator capable of ini~iating polymerisation
of the monomer whereby the composition may be rendered
water-insoluble by radiation.
Bqlgian Pate~t`No.789,950 descrlbes the photopoly~
merisation of ethylenically unsaturated material . ~:
-
uslrlg a photo~inl~iator comprising
(i~ at least one photosensitiser havi~g the struc~ure
~ ~~(X)n~~
c~ , .
where x is ~C=0, ~CR1R2 or ~CR30R4, Rl t ~ ~
may be the same or dif:Eerent, are hydxogen or hydro-
carbyl groups; n ls O or 1 and the groups A9 which
may be the same or different, are hydrocarbyl or
substi~uted hydrocarbyl groups, the groups A beins
aromatic or substituted aromatic when n is ~ and
X i~ ~CR1~2 ~nd also when n is ~, and
' ~ ~ . ;
' : '
- : .
, . . .
~ ~7 ~ ~6 ~
tii) at least one reducing ayenk capable o~ reducing
the photosensitiser when the photosensitiser is
~n a p~oto~exc~ted state~
We have now found that it may be advantageous to employ
S as the polymer or copoLymer in the photopolymerisable
composition of Patent No.820,404 a compound capable
of acti~g also as the reducing age~t o Pa~ent No~789~950 ~ -
in association with the photoinitiator of the latter
applicationO :~
` 10 . Thus the present in~ention pro~ides a photopol~merisable
; composition comprising (a) a water-soluble or water-dispersib.~e
polymer or copolymer, or a polymer or copolymer mixture in
which one or more of the components is watex~soluble or
water-disperslble, (b) an addition~polymeri.sable ~onomer
, 15 which is soluble in or compatible with a solven~ or d~spersing
! medium for ~a); and (c) at least one photosensitiser having
the s~ructure
A~-(X)n-A
O
where X ls C=0, >CRlR2 or ~CR30R4, Xl to ~4; whi y
the same or different are hydro~en or hydrocarbyl groups,
n ls 0 or 1 and the ~roups A, which may be the same or
, different are hydrocarbyl or substitu~ed hydrocarhyl groups,
; : the groups A being aromatic or subs~ituted aromatic when
n is 1 and X ls >~RlR2 and also when n is 0, polymeric component
(a) being capable of reducing photosensitlser (c) when said ~. :
photosens~iser is in a~ ~xcited state to effec~ addi~ion ~-
_ ~ ~
- : .........
~ ~.' ' . , .
~795~ 1
pol~me~isation of at least a proportio~ of components
~a) and (b) oE the composition
Polymeric component (a) preferably compxises a
reducing comp~nent having the structure s-~-B where M is
an element of Group Vb of the Periodic Table of the
Elements, at least one of the units B having a ~arbon atom
which forms part of the polymer chain o the polymeric
component (a) and at least one other of units B, being ~¦
hydrogen, hydrocarbyl, substituted hydrocarbyl, or a group
10 in ~hich two units B together with the element M form a. :~
ring system, and where the element M is attached directly
to an aromatic group, at least one of the other groups B
has a - ~ - group attached to M
; , . .
Preferably polymeric component (a) comprises a :
poly- (N-vinyl pyrrolidone) and, optionally, a vinyl :
acetate component.
The reducing component of the polymer should
nave a reduction potential such that in the con~entration
in which it is incorporatad in the ~.~nposition it is
capable of reducing the photosensitiser when ~he photo-
sensitiser is in an excited state yet is incapable of
reducing the photosensitiser when the latter is not excited
~y radiation The reducing component, at the conce~tration.
at which it is present in the nhotopolymerisable composition, ¦.
should have little or no inhibiting effect on polymerisation.
:~ The Peroidic Table of the Elements referred to ~- .
is that published ln "Advanced Inorganic Chemistry", second ~ ..
~4~
.-
. : ~ .
'
':
:
~.
- , , - ~ . . . . .
. ., . : .. . : -
3 a~7~
edition, by F A cotton ancl G Wilkinson (Int~rscience
1966), and element M may be, for example, phosphorus or
more preferably nitrog~n If desire~ M may be ~xsenic
or antimon~ and throughout this specifi-cation where
reference is made to specific examples of reducing
components in which M is nitrogen we tend ~lso, where
they are suitable, to include corresponding ex~mples in
which M is phosphorus, arsenic or antimony
The reducing ¢omponent may be primary,secondary or
tertiary; that is, in the structure B-~-B two, one or
none of the units B may be hydrogen atoms For example,
the reducing component may be derived frc~ a p~imary,
; secondary or tertiary amine or phosphine ~:-
One or ~ore of the groups B may be ~ydrocarbyl
and the hydrocarbyl group may be, for example, alkyl,
cyclo-alkyl or alkaryl. PreEerably, one or more o~ group :
is an alkyl group having from 1 to 10 carbon atoms.
Examples of suitable reducing components in :~
' which one or more of the units B is hydrocarbyl are those
~0 notionally deri~ed from propylamine, n-butylamine,
~entylamine, hexylamine, dimethylamine, diethylamine,
dipropylamine, di-n-butylamine, dipentylamine, trimethyl-
amine, triethylamine, tripropylamine, tri-n-butylamine,
tripen~ylamine, dimethylaminoethyl methacrylate, and :.
long chain fatty amines, e,g. Cl8H37NMe2
Thus the reducing component is conveniently
introduced into the polymer by copolymerlsation.
Suitable reducing .
-5- .
.
.
~ 6 ~
comonomers in which one or more of the units B is hydro-
carbyl are for example the following esters of a
methacrylic acid.
2-amino ethyl
3-amino 2 hydroxypropyl
2-amino propyl
4-amino butyl
5-amino pentyl
6-aminobenzyl
N-methyl amino ethyl
2-N ethyl amino ethyl
3-N propyl am~no propyL
N-methyl amino methyl
4-N-butyl amino butyl
5 N-pentyl amino pentyl
NN_dimethyl amino methyl
2 N,Ndimethyl amino ethyl
3 NN-d1propyl amino propyl
4 NN-dibu~yl amino butyl ...
NN_d~pentyl amino pentyl
Examples of reducing components containing aromatic
groups include those notionally derived from N,N'-dimethyl
aniline, N-methyl diphenylamine, p-(N,N-dimethyl amino)
styrene, 2 a~ilinoethyl methacrylate, 2-p methoxy anilino-
ethyl methacrylate, 2-anilino l-methyl ethyl acrylate.
One or more of the units B may be a substituted
hydrocarbyl group and in particular the hydrocarbyl grou~
may carry a substituent having the structure - R2 ~ M
R3
- 6 -
'~
~ ..... .. . . ., : - .. : . . -
- . . . . . ::
- : - . . . ,. . : - . : . - . . , .: , - - . . -
- . - : : .. . -
. : - . . .
where M is an element of Group Vb of the Peri.odic Table
of the Elements and the unit R2 is, for example, an
alkylene chain and the units R3 which may be the same
or different, are hydrogen atoms or hydrocarbyl groups,
especially alkyl (particularly Cl-C4) groups.
B Examples of reducing components having the structure
B-M-B in which at least one of the units B is a substituted
hydrocarbyl group include notional derlvatives of the
structure
~ N - (CH2) n - N \
R3 R3
in which n is a whole number of at least two and the
groups R3, which may be the same or different, are hydrogen
atom~ or hydrocarbyl, especially alkyl groups For
example, the reducing component may be notionally derived
from ethylene d~amine~ trimethylene diamine, tetramethylene
diamine, pentamethylene diamine or hexamethylen~ diamine,
or N-hydrocarbyl, especially N-alkyl derivatives thereof.
~0 Examples of such copolymerisable monomers are the
following esters of ~meth)acrylic acid:-
1,3 bis-(dimethylamino)isopropyl
1, 3 bis- tdiethylamino)isopropyl
N-~diethylaminoethyl) N-methylami~o methyl
Other suitable reducing component. include ~o~ional
. derivatives of compound~ having the structure
R3 \ / R3
/ N (CH2~n N \
R3 R3
. . 7
~ .
-.. . . -. . . . - : .. - .. : . ~ . :.. . ..
. , .. : .. . . . .. :, ... .. ~. .. . . . . . . . .
, - . . . ... . - . .
.:: . .~: . . . . . , . : . - -
.. : . ~ . ' ~ . -
-
.- . -
~1'0'7',956J,
in wh.ich one or more of the hydrogen atoms in the -CH2
unit is suk,stituted by an - N~ 3 group, especially an
-NH2 group-
Ex,~mples of reducing componen~s in which th~e element
M forms part of a ring system include those notionally
derived from piperidine, and N~hydrocarbyl, especially
N-alkyl, derivatives of piperidine fox ex,ample 1,3 bis
(di-piperidinomethyl)isopropyl metha~-rylate.
Other reducing components include those notionally
derived from tri,allylamine, lallyl)~-N-C~2- ~ CH2 N
~allyl?2, allyl thiourea,o-tolyl thlourea, soluble salts
c,f aromatic sulphinic acids, e.g. S-benzyl iso-thiuroni~m,
p-toluene sulphinate, ,and sodium diethyl dithiophosphate.
I Incorpora~ion of the reducing componen~ into the
i 15 polymeric compon~ent of the composition, or preparation of
! a polymeric component containing such a reducing co~ponent
I according to the invention, may be by known techniques
. ..
for polymer preparation and will present no difficulty
I to the skilled man. Suitable preparative ~ethods include
i 20 copolymerisation of the polymeric component of the
composltion with a material compri5ing the reduciny
component and copolymeris,,~ble with the said polymeric
component~
A particularly suitable me~hod ~o~ incorpora~ing the
reduclng component is by free radical fropolymeris~tion
using for instance amino alcohol esters o~ (meth)acrylic
' acid.
.
8 -
' ~:
- : '.
- . . .
.. ~ .
.
.
~ 1~'7~
The reducing component can also be introduced by
reacting an existing polymer, for example poly~inyl
alcohol, with an amino aldehyde. Monomers containing
acid functions should not be employedO
Polycondensation techniques may also be employed
where appropriate.
Suitably the concentration of the reducing component
in the composition may be in the range 0.001% to 50~ by
weight of addition-polymerlsable or ethylenically
lo unsaturated material in the composition although concen-
trations outside these ranges may be used if desired.
Preferably, the reducing component is present in a
concentration of 1% to 10% by weight of the ethylenically
unsaturated material in the composition.
Where o~e or more of the groups B in the reducing
component B-~-B is aromatic then it is preferred to have
a concentration of reducing component is the photopoly-
merisable composition in the range OoOl~ to 0.5% by weight
of ethylenically unsaturated material in ~he compositio~.
Typical water-soluble polymers include hydroxyethyl
cellulose, polyvinyl pyridine, sulphonated polystyrene,
and partially hydrolysed polyvinyl acetate.
Component (a) comprises a water-~oluble polymer
either alone or in admixture or copolymerised with one
or more less water-soluble polymers or monomers (as
appropr~ate~, examples of which are polyacrylates, poly-
alkyl acrylates (e.g. polymethyl acrylate, 2-ethyl hexyl
acrylate), polyalk~l methacrylates (e.g. polymethyl
_ g _ ,,
' ' ' ' ' '. .`.- - ' . . .
methacrylate~ lauryl methacrylate), dialkyl maleates
(e.g. di-iso-octyl maleate, di-butyl maleate, diethyl
maleate).
Selection of the ingredient(s) of component (a) will
be made in the light of the requirement that it should be
capable of being washed from a film of material using
an aqueous liquid, preferably water, i e. that it should
be water-soluble or water dispersible. Preferably also
the composition is soluble in an alcohol or other
convenient solvent for ease of film formation.
Our preferred component (a) comprises poly(N-vinyl-
pyrrolidone), either alone or in admix~ure with polyvinyl-
acetate, or a copolymer of N-vinylpyrrolidone and vinyl
acetate. The polyt~-vinylpyrrolidone) and the copolymer
of N-vinylpyrrolidone and vinyl acetate are both water
and lower alcohol (e.g. methanol and ethanol) soluble,
and we have found this advantageous because formation of
the composition of the invention into a film from a
solution is one of the lower alcohols (i.e. up to C4) is
pref~rred~ Substitution derivatives of the components,-
where suitable may also be employed, of course.
The component (a~ will usually be present in he
composition in an amount forming from 50% to 95~ by weight,
the water solubl~ polymer preferably foxming 30-70% of
the total of (a~.
The monomer employed is one which is pxeferably,
although not necessarLly, water insoluble. It i8 desirable
of course tha~ the monomer be hlghly compati~le with the
`~ 10 --
.~ . ~ . . . :
, ~
. . . - . .. . .
- - : . :: .. . - , :
5~L
polymeric and any other components of the composition,
and capable of polymerising. with at least one of component
(a) to form a water-insoluble product. Preferably the
monomer comprises at least two non-conjugated ethyl~nic
double bonds, and prefexably has terminal unsaturation.
As examples of suitable monomers we would ~ention
(1) N (CH2CH20f ~ C a CH2) 2
~here R = H or CH3; in which the ~enæene ring may contai~
one or more substituents which may be the same or
di~erent, incl~ding alkyl groups up to 4 car~on atoms,
-COOH, halogen, -COORl in which R, is a lower (e.;g. up to
4 carbon atoms~ alkyl group~ -S02 NR2 R3 or -CONR4R5
where R2, R3, R~ and R5 each represents H or a lower
alkyl group.
e~g. N:N-bis-~-acryloyl oxyethyl) aniline
N:N-bis~ methacryloyloxyethyl) m toluidine
- ~ N:N (ac~yloyloxyethyl~-chloro aniline
(2) CH2 - C - CONH(C~2)30tCH2)20(CH2)3H 2
where R - H-or CH3.
e.g. 1,2-(yacrylamidopropoxy)ethane
1,2-(yme~hacrylamidopropoxy)ethane
(3) Acrylates,
; e.g. allyl methacrylate
e~hylene glycol dimethacrylate
~ ~ trim~thylol propane triacrylate
:
. :, .
; .............. . .
,
trimethylol propane trimethacrylate
pentaerythritol tetra acrylate
pentaerythritol mono hydroxy triacrylate.
(4) vinyl urethanes,
e.gc a reaction product of di(4-isocyanatophenyl)methane,
polypropylene glycol and 2-hydroxyethyl methacrylate in
mole ratio 2:1:2.
Reaction product of tolylene diisocyanate, penta-
exythritol/propylene oxide adduct, and 2-hydroxyethyl
methacrylate in mole ratio 4:1:4;
~5) Allyl monomers
e.g. triallyl cyanurate.
The proportion of monomer in the composition will
vary within wide limits but will usually lie within the
range 5% to 50% by weight, preferably 10 to 25~ by
weight of the composition.
It wlll be appreciated that, although not preferred,
component (b) could be an oligomer, that is a short
polymeric chain having up to 8~ say, 5 repeating
monomeric units.
The reducing component of the polymer should
naturally be one which does no~ adversely affect the
~ater-soluble or water-dispersible property of the
pol~mer to an undesixable degree, and it will ~e selected
accordingly.
The photosensitiser employed accordlng to the
present invention may be any suitable compound. In
particular according ~o the invention ~e prefer to employ
.. ~.
'' ~ ,~, '. . '
~ ;, ~. .. .
a photosensitiser as described, and in the proportions
indicated~ in selgian Patent No.789,950.
In general the groups A in the photosensitiser
will be aliphatic or aromatic and it is to be understood
that the groups A may be the same or different, that is,
for example, in the pho-tosensitiser of struc~ure I both
groups A may be aromatic, or both may be aliphatic, or
one group A may be aromatic and the other aliphatic
provided that when n is l and X is >CRlR2, and when n is
0, ~oth groups ~ are aromatic. Howev~r, for reasons of
convenience in the prepaxation of the photosensitiser
the groups A are preferably the same.
~7
. .
:~ ,
- 13 ~-
.
.. ~
. -
.. ~ .
Within the scope of the term aliphatic groups we
include cycloaliphatic groUpS and aliphatic groups carrying
aromatic subs~ituents, that is, alkaryl groupS. Similarly,
within the scope of the term aromatic group we include
S groups carrying alkyl substi~uents, that ls~ aralkyl grouPs.
The aromatic group may be a benzenoid aromatic group,
e.g. the phenyl group, or it may be a non-ben~enoid cyclic
group which is recognised ln the art as possessing the
chaxacteristics of a benzenoid aromatic group.
The groups A, especially when aromatic, may carry
substituent groups other than hydrocarbyl, e. g. halogen
or alkoxy, provided the photos~nsikiser containing the
substituents groups is not present ln the photopolymerisable
composition in such a concentration as to result in
substantial inhibition of pol~merisation of the ethylen-
ically unsaturated material in the composition.
In the photosensitlser having the structure I the
group X preferably has the structure ~C=0 or ~CR30R4
where R3 and R4 are a~ hereinbe~ore described.
The groups ~1' R2~ R3 and R4 ma~ be hydrogen or
hydrocarbyl groups, for example alkyl. Preferably the
groups Rl to R4 are hydrogen.
In the photosensitiser having the structure I the
groups A may be further linked tog~ther by a direct link,
or by a ~ivalen~ group, e.g. a dlvalent hydrocarbyl group,
that is~ in addition to the link through the group
~ ~ ~ tX~n - the groups B may be further lLnked so as to
. - ,
,. , : . . : : .
:- . : : - ~ . - :
, : . :
~ ~ 7 ~ 5 ~ ~
forn~ ~ cyelic ring system. -~or example, wh~re the groups
A are aromatic the photosensitiser may have the structure
(Y)m
~ - (X~ ~ II
in which X and n are as hereinbefore described, Y is
~CH2, or hydrocarbyl derivative thereof, and m is o,
1 or 2. Preferably, the group Y is linked ~o the aromatic
groups in positions ortho ~o the group - ~ - (X)n -
The groups A togethex may orm a fused aromatic rlng
system.
Particularly preferred photosensiti~ers on account
of the rapid rates at which the ethylenically unsaturated
ma~exial may be polymerised are a-diketones having the
structure I in which X ls >C=0 and n is 1. In general r
the a-diketone~ are capable of being excited by radia~ion
in the visible region of the spectrum, that is, by light
: having a wavelength greater than 400 m~, e.g. in thP
. . .~15 w velength:~ange 403 m~ to 500 m~, although ultraviolet
radiation or a mixture o~ ultraviolet radiation and
viæible light, ma~ be used. Suitable -diketone photo-
sensltisers include biacetyl in which both groups A are
methyl, bqnzil in which both groups A are phenyl, ~-
-
dlketon~s ln which buth of the groups A are fused aromtic,
e.g. a-naphthil and B naphthil, and ~-diketones in which
: ~ the groups A are aralkyl groups~ e.g. p-tolil. As an
~ `: example of a suitakle a-diketone pho~osensitiser in which
:: ,
~ 15
, ~ : : . ;- . . . . . ... . .
.
.
~ S 6 ~
the groups A are non-benzenoid aromatic there may be
mentioned furil in which the groups A have the struckure
~ ~ e.g. 2:2'-furil. In ~he a-diketone photo-
sensitiser the groups ~ may carry non~hydrocarbyl groups,
S for exampl~, the photosensitiser may be p,p'-dialkoxy
benzil, e.g. p,p'-dimethoxy benzil, or p,p'-dihalobenzil,
eOg. p,p'-dichloxobenzil, or p-nitrobenzil.
In the photosensitiser having the structure I, n may
be zero in which case the groups A are aromatic or
subs~ituted aromatic. An example of such a photosensitiser
is benzophenone in which both the groups A are phenyl.
Further suitable photosensitisers include those
having the structure I in which n is l and X is >CR30R4.
For example, ~he photosensitiser may be ben~oin in which
R3 and R4 and H and both the grou~s A are phenyl, an alkyl
benzoin in which R3 is hydrogen and R4 is alkyl, e.g.
methyl, a-naphthoin and ~-naphthoi~ in which both the
groups A are fused aro~atic, p,p'-dialkoxy benzoin, e.g.
p,pl-dime~hoxy benzoin, and p,p'-dihalobenzoin, e.g.
p,p'-di~hlorobenzoin, in which the groups A oarry non-
hydrocarbyl groups, and furoin in which the groups A are
non-benzenoid aromatic and have the structure
e.g 2,2'-furoin.
In the photosensitiser the groups A may b~ linked
together by a direct link or by a divalent hyd~ocarbyl
group to form a cyclic ring system~ For example where the
groups A are aliphatic the photosensitiser may be
c~mphorquinone.
- - 16 -
. . . .
- , .: . . - ,
;
.- ~ . . , - . . ^ .. .
3L~7~56~
. .
Where the photosensitisar has the structure II
suitable photosensitisers include fluorenone in which
n and m are both zero and the aromatic groups A are
linked by a direct link ortho to the group - C - (X)n -,
and phenanthraquinone in which X is >C=0', n is 1, and m
is 0, the aromatic groups A being linked by a direct link
ortho to the group - C ~ (X)~ ~. The photosensitiser may
be acenaphthene quinone in which the groups A in structure
I together form a fused aromatic ring system.
~he photosensitlser may, for example, be present in
the photopolymerisable composition ln a concentration in
the range 0.001% to 10% by weight of the ethylenically
unsaturated material in the composition although concen-
trations outside these ranges may be preferred.
The method of mixing.of the photosensistiser with
the ethylenlcally unsaturated material may have a bearing
on the succesR or otherwise of achieving the desired
concen~rations of photos~nsitiser and reducing agent
: therein.
- 20 Thus, where the photosensi~iser is no~ suficiently
soluble in the ethylenically unsa~ura~ed matexial, or
where one or the other may be dissolved only with
difficulty, we have found that dissolution of the photo-
sensltlser may be assisted by addition to the ethylenically
unsaturated material of a small amount of a diluent in
. whlch the photosensitiser is soluble and which is :
mlscible with the ethylenically unsaturated material.
17 ~
:
.... ~. ,. . , . .. . . . , . : ~ .
- ~ . . . . . . : .
:: : :
.
- : .
- . . . , , :
,.' ' .'' . ' - ' ~ : '' :
~ S 6 ~
Suitably, the photosensitiser may be intxoduced into
the ethylenically unsaturated material in the form of
a solution in such a diluent.
According to a further embodiment of the lnvention
there i5 provided a process for the preparation o a
polymeric material which comprises irradiating a photo-
polymerisable composition as herein described with
radiation having a wavelength which i5 capable of being
absorbed by the photosensitiser so as to convert the
photosensitiser to an excited state.
The radiation may be visible light or ultraviolet
radiation or radiation which includes within its spectrum
radiation of both visible and ultraviolet wavelengths.
Suitably, the radiation may have a wavelength in the
range 230 m~ ~o 600 m~. Sunlight may be used as ,the
sourcP o~ radiation although the wavelength of radiation
to be used will be determined by the particular photo-
sen~itiser in the composition, the radiation being of a
wavelength such a~ ~o be absorbed by the photosensitiser
so as to convert the photosensitiser to an excited state.
A suitable wavelength may be chosen by means of simple
experiment e.g. by measuring the electronic absorption
spectrum of the photosensitiser.
In general, polymerisation of the ethylenically
unsaturated material proceeds readily at ambient temperature
when the composition 1s irradiated with radiation having
a wavelength which converts the photosensitiser to an
18 -
- ~
. , . -. . .
-, ' . ' : '. ~ .. ' :
- . . - ~ . : . .
3L~7~356,1
excited state. However, the rate of poly~erisation may
in general be increased by effecting the polymerisation
at a temperature above ambient.
The invention provides photopolymerisable compositions
which may be developed (that is, unexposed areas removed)
by treatmen~ with water or an aqueous liquid, and the
compositions may be employed for example in the preparation
of coated sheet materialsl carrying a layer of the
composit~on. Such sheet material~ may be employed for
` example as printing plates. Other uses for the compositions
include photo-resist applications.
According to anokher aspect of the invention there-
for, we provide a carrier having dep~sited thereon a
photopolymerisable composition as hereinbefore described.
Preferably the carrier will be a sheet together with a
- layer of the composition deposited upon at least one
surface thereof. A particular application o~ such a
sheet product is in the production of relief plates
whlch are capable, af~er suitable processing, of being
used both for direct or offset letterpress printing
flexo printing, flexo-printing or as pattern plates
as described fully in Belgian Patent No.820,404, and
accordingly another a~pect of the lnvention provides a
" ~ ., , . , ,, "
method of preparing reIief pl tes ~y selectivi~y exposing
- - - . .. . . .
a composition according to the invention to appropriate
radiation, fsr example through a negative, and developing
the exposed composition (convenien~ly in the form of a
sheet upon a substrate).
19
,., , - , , . : . . .
, . . , ~:
: . :
, - . , .
. : : . . .
.
s~
The invention is illustrated by the following examples:-
Example 1
Preparation of Polymer
A mixture of vinyl acetate (100 gm), vinyl pyrrolidone
(100 gm), dimethylamino ethyl methacrylate (4 ~m) and azobis
iso-butyronitrile (2 gm) was added to ref~uxing industrial
methylated spirits (160 gm). The mixture was refluxed in
a nitrogen atmosphere ~or a total of 14 hours. A viscous
straw coloured solution was obtained.
_ _
The above solution ~100 gm) was mixed with ethylene
glycol dimethacrylate (11 gm), benzil (1.65 gm) and dimethyl
phthalate (5.5 gm). The mi~tu~e was spread on to a steel
shee~ and dri`ed by heating at 60C for 1 hour and 85C for
1 hour to yield a coating 0.5 mm thick.
The dried plate was exposed through a negative to ultra
violet radiation for 5 mins and then washed for 4 minutes
with a spray of water to give a relief image. After drying
; at 105C for 10 minutes the plate was suitable for use as
a let~erpress printing plate. The plate was ~uite flexi~le
and after processing could be ormed round a roller of
4 cm diamster.
Exam~le 2
167 parts of 60% solution o~ copoly(vlnyl acetate/vinyl
pyrrolidone), made by polymerislng a mixture of equal weights
of vinyl pyxrolidone and vinyl acetate in industrial methylated
spirits, was mixed with 20 paxts of ethylene glycol dimeth-
acrylate, 10 parts of dlmethyl phthalate, 2 parts dimethyl
..... _ . ................. . . .....
- 20
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amino ethyl methacrylate and 2 parts benzilO A portion
of the solution was used to prepare a printin~ plate
as described in Example 1. After exposure and wash-
out, the plate cracked on being formed round a 4 cm
diameter roller.
Plates were prepared as described ln ~xample 1 using
different photoini~ia~ors at various concentrations ln
the following basic composition:-
vinyl pyrrolidone:vinyl aceta~e-dimethyl~minoethyl
methacrylate polymer ~50:50:2) 100 pts
ethylene glycol dime~hacrylate ~0 pts
Cereclor - 50LV* 10 pts
The dxied plates were exposed to W radiation
through a "By Chrome"*screen tint negativeO The exposur~
times quoted are those which were requirea to retain th~
5~ dots on the plate after processin~ as described in
Example 1. . . .
. ~oncentration of gxposure
~ ~ (m
3 t-Bu~yl anthraquinone 0O01 6
4 1I n n n O o l 6
1~ n n n 10 O . 7 5
6 ~ 1. 0 10
' 25 7 Fluorenone 0.01 ~12
8 n n n O. 1 S
9 ~ 00 5 5
10 . ~ 1 . 0 5
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1~77~5t;~
. . . Concentration of Exposure
Exam~le Photolnltlator
~) ~mins
11 Ben20phenone 3.0 5
12 A plate was made using vinyl pyrrolidone:vinyl
acetate copolymer (50:50) in place of the
copolymer in the composition of Example 11.
An exposure of 12 minutes was found to be necessary
~o retain the 5~ dots.
~K~o~le~ 7
Plates were prepared as described as in Example 1
but using polymer with different amounts of reducing agent
in the composition.
vinyl pyrrolldone:vinyl acetate:dimethylamino ethyl
methacrylate (50:50:various) 100 pts
ethyle~e glycol dimethacrylate 20 pts
Cereclor -50 LV 10 pts
t-Butyl anthraquinone 0.75 pks
~ - EXposur~ time
.
` 20 13 0 1~
14 ~ ~.0 8
5.0 10
16 7.5 12
1:7 10.0 >lS
. - 25 The plates were:exposed to UV radiation th~ough a
By Chrome screen tlnt negative and the exposure time
indicated is that required to retain the 5~ dots on the
plate after processing.
. ,
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Exam~le_18
A plate was prepared as in Example 1 but replacing
the ethylene glycol dimethacryla~e by polyethylene
glycol dimethacrylate (Sartomer 210 - available ~rom
Sartomer Resins~ Inc). The processed pla~e showed good
flexibility and could be ormed round a roller of 4 cm
diameter.
Example 19
A plate was made using the polymer described in
Example 1~ The composition was:
polymer 100 pts
eth~lene glycol dimethacryl~te 20 pts
di-isobutyl phthalate 20 pts
fluorenone 1 pt
:1 15 The plate was exposed through. a negative to W
radiation for 5 minutes. The unexposed areas of polymer
were removed by washing with a water spray for 4 minutes.
~ After drying~ the plate was used on a rotary newpaper
`, - press. After 300,000 impressio~s the prints were still
¦ 20 of good quality.
: *Trade Mark
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