CA2068586A1

CA2068586A1 - Formation of images

Info

Publication number: CA2068586A1
Application number: CA 2068586
Authority: CA
Inventors: Andrew E. Matthews; David E. Murray; Allen P. Gates
Original assignee: Andrew E. Matthews; David E. Murray; Allen P. Gates; Du Pont (Uk) Ltd.
Current assignee: Du Pont UK Ltd
Priority date: 1991-05-14
Filing date: 1992-05-13
Publication date: 1992-11-15
Also published as: GB9110417D0; EP0514145A1

Abstract

ABSTRACT
Improvement in or relating to the formation of images Images are formed by directing radiation, such as red or infra-red laser light, at a radiation, sensitive plate and modulating the radiation. The radiation-sensitive plate includes a coating comprising core-shell particles having a water insoluble heat softenable core component and a shell component which is soluble or swellable in aqueous alkaline medium.
The radiation causes selected particles to coalesce, at least partially, to form an image and the non-coalesced particles are then selectively removed by means of an aqueous alkaline developer.

Description

2~8~86 2~p~ ln ~ ~ o ~h~

q~hi~ inverltion re~ates to lma~e formation ~nn ~on~rned wlth the ~orm~tion of lm~7es dir~ctl~ ~rom e~ ~c~xonicall~ ~ompo~ed ~ ;al gourc~s .
For many year~ lt has ~een ~ long term ~lm in the p~nt~n~ Inc~ r~ ~o f~rm prlntin~r lma~ dir~c:tls~ fr~m ~n e~ec:~xonlcally c;o~po~ lglt~l ~Rt~ba~s i . e ~ by a alle~ "~omp~ter-~o-pla~" 3yYt~ . trhe ~ant~ge o ao ~u~ yt:iL~ l UV~l ~,n~ ,1U~I1 ~ ~r ."~
pr~nting pl~te~ a~e:-(i) the ellmlnation of the ~o~tlylnl;~3rmedia~e ~llver ~ilm ~n~ pro~essiny chemlc~
(il) ~ savlng of ti~ n~
~5 ( ii~ e ~ility to ~utomate the ~y~tem wl~h ~on~eg-lerlt re~uG~ion ~n labaur co~t~.
Th~ int~od~lctlon of laser t~hnolog~ provlded th~
opportur~ity to ~ an ~mage direc~ly on ~
l?rintln~ plat~ b~ direc~inS~ s~3r bealn at ~e~uen~lal 20 ~r~as Of the plate ~n~l modulating the beam So ~
~rar~ i~s int~nslty. In thl~ Way, radlatlon ~n~itlve plate~ c:omprlsing ~ hl~h ~n~l~ivlty photocro3~ ble pol~ner coating have been exposed to wa~er cooleq W
~on-lon l~ser3 Elnd electrophotographlo pl~tes having 2$ sensitivi~y ~tretchin~ from th~ vlsibl~ sp~t~l region into the near in~ra-red region h~ve ~en ~u~ces~ull~
~xpo~ed uslng low powe~e~ ~ir-cool~d argon-ion ~n~
~emlconductor la~er de~ice~.
Xm~ing ~ystems ~r~ also availa~l~ which involve sandwich ~tru~ure which, on exposur~ to a heat gana~ating Infr~-red l~ser ~e~m, un~argoes ~elec~lv~
( image-wi8~ ) ~al~min~tic~n An~ sub5equ~nt tran~er of material~. Such ~o-called peel-apart ~ystems a~
~an~r~lly ~ed hs replacements fo~ sllvar h~llde ~ilm3 3$ Ac~ordlng to on~ a pect of the pr~ent lnv~ntion there i3 provided ~ radiation sensitlve plate whl~h 2 ~
~2~
c:omprise~ ~ substr~te c:o~ted wlth ( 1 ~ one ~r more layQr~ ~3ach compr:L~in~ core-ahell par~cle~ e~ch o~
which compri~e~ a wa~er-ln~oluble h~t soften~ble ~ore c~omponen-t ( A ) ~nd ~ ~h~ll componen~ ( s ) whlch i~
5 ~oluble o~ ~w~3llabl~ in ~!lqU~30UQ alkaline ~e~ium, ~n~l ~li) a ~ubs~anc:e capable of strongly ~sorb:Lng radlatio1n and transferr~in~ ths ener~y thu~ obtalned hea~ ~o ths core-~hall par~icleR ~o tha~ at l~a~
p~r~ial çoale~cence of the p~rti~les occ~rs.
The plate m~y cc1ntain on~ or more A~dl~cion~l lay~s so a~ to ~ncre~se ~dhe~lon to the ~ub~trate, lmprov~ ~esi~tance ~o abr~lon, or to lmpro~te ~hP.
perform~nc:~ of th~ ~stem in other re~pact~.
~ oordin~ to another B8p~ 0~ the prasent ~ n~en~lon ~h~e 1~ pl~ovld~d ~ Inethod of fo~mlng ~n ~nlaga whloh c:ompri~es ( a ) prc)vldins~ ~ ~adi~tlon ~ensitive plate herelnabove de~ln~, (b) imag~-wi~e expo~ln3~f ~h~ radla~lon-~ensltiv~
pl~te to a be~n~ of high intensl~cy r~dlation, ~y ~lr~ctlng the r~stion ~t ~e~uen~cial ~rea~ of ~he c:oating an~ modulat;ln~ ~he ~a~liatlon ~o th~t ~hs partiole~; in the ooa~in~ are ~3~31ec:tlvel~
partiall~ c~o~ ced, ~nd ( ::) developin~ the ~m~ge-wl~e ~epo~d pl~te with ~queo~ lkalln~ m~dium to ~ele~kively rernove the ~re~
cont~lrlin~ the non~ oal~ce~ p~rticle8 ~nd leave ~n image on the sub~trate ~e~ultlng frorn the ~t :Lea~t p~r~:ially co&l1e~ce~ p~rticle~.
It may he ~esir~1e ~o in~reas~ ~he d~3~ree o~
~oa1e~c~enoe of the s~1sc:~civ~1y coa1esced core-~he11 p~rtic1~s or to inc~re~se the sdhesion of the lma~ to th~3 ~ub~t~rat~. This Inay be ~c}liev~d after the se1e ::tlve removal o~ the non-coa1~Yce~ partic1es by 3$ hea~ing ~he p1ate to a te~perature, and fo~ ~ ~irne, ~u~f1clent to further ~often v~ me1t the p~rtic1e~, Mnd _3~ 8 ~ ~ ~
to ~rlng sbout the ~si~e~ qt.
The ~ub~tr~ts materl~l usf~d ~ependY upon the purpo~e ~or ~hich the lm~g~ 1~ to b~ u~ed ~n~ m~y b-3, ~o~ ~xalnple, o~med o~ me'c~l or pl86~tlc~3 m~t~rl~1. In 5 ~he c~ae where the image 1~ ~o be u~ed ~s ~ prlntlng imaga, the ~u~t~t3 i~ pr~s~1y electro~hemic~lly tr~ated. ellumlnium wher~as the sub~r te may be ~ llne~r polye~ter ~n the c:a~3~3 wher~3 ~ tr~n3par~ncy 1~ to be produced or copper in th~3 ca~ where th~ lmage 1~ to be 10 ~l~ed ln print~3d s~:lrc~ult ~o~rd n~nu~cture.
~ he aore-~hell pPIrtlcle~ contsln dl~tinct C~omain~i of componants ( A ~ nn~ t ~ ) . Tha domain~ are ~r~n~ed 80 tha~ c:omponent ( A ~ ~ the core ) 1~ enc~psulat~ by c:omporlen~ ( ~ ) ( the h~ll ) with th~ coxa an~ shell bsi~ç~
1~ lln~ed to ~3ach other by ~ron~ phy~;lcal ftdsorptlon or, nlor~ p~f~ferably, by chemical bonding. IJn~er amblent ~on~i~lon~, bo~h ~omponents ~r0 praf~ably ~olid ~n~
immobll~ a ge~er~llty; ~ore-shell p~rtic;:las ar~3 ~nown ana m~thods ior pr~p~rlng the ~ama ~r~ de~orib~
20 ln US pa~nt ~peclicatlol No~4~5~01~ ~nd ln Britl~h at~nt specl~icatlons ~c~. 8873S6 an~ No. 1107~49 ( Ex~mpl~
~2) .
qlhe component (A) is ~n oleophillc polyTner, pref~ar~bly h~rin~ mlni~ m ~llm ~c:rmin~ tenlper~tu~e ~S (MFT) ~bove ~mbiQn~ temper~ure, ~n~ m~y ~e ~n ~ ion p~lym~ ~ompri~ln~ r~ldue~ ~erlv~ from one o~ m~re of styr~n~ ub~ti~uted ~tyrenes, e~ rs of (meth)ac~llc ~cid, vlnyl halld~, (meth)aorylon~rile, vlnyl e~te~
o~ poly~th~r~, o~ 1~ m~y ~e a pol~ster, pol~mide or polyur~hana, or ~ny ~her~al~y fu~bl~ oleophilic m~terial o~ compo3itlon c~pable o~ formlng ~ co~e-$hel ~trw~re ~ deflned a~ov~. Prefer~d materi~ e ~dditl~n polym~rs ~ontalnin~ ~0% or more by wei~ht o~
~tyrene or ~ub~tit~te~ ~tyrene~.
Th~ compon~nt (s) is pr~afer~bly polyme~ic, ~n,~
contaln~ carbox~llc aold, ~ulphonamido, ~r other group~

2 ~

cap~t~le of c~onf~rring solubility, cr at le~t ~well~bil~y, ln ~qu~ou~ Alk~l~ne ~u~orl~.
Pa~ti~uJ~rly sul~b~ materiill3 ~or aomPon n~ ~B) elre:
1: ) copolym~ derivea from the ~opolymerl~tion c)~ ~n~
5 or mo~e e~hylenically un~turat~3d c;arboxy~ic ~clds ~ h one ~ more of ~;tyrene, sub~tit~ted ~tyrene~, ~me~h)ac:rylht~3 e~ r~, (mekh~ac~ nl~rlle or vinyl ac~3tate; ii ) dic:~Lrboxyllc ac:ld half-8~ters of hydl~oxyl group-c:ont~nlng po~ymer~, ~uc~h ~ phthall~, succln~c 10 or mal~ aid ~f ~3ster~ o~ ~ polyvi~y~ ~cet~l ~n~, ~n p~rtic~ r, ~ R pol~vinyl butyral; ~nd iii ) ~llcyl or ~ kyl half e~3ter~ of 13tyr~ne~ or alkly vin~l ~3ther~malela llnh~drlds ~opolym~ , in p~lcular ~lk~l hslf es~er~ of ~;~yrene-mal~ anhy~I~ide copolym~r~ ~uch 15 ~ ~crip~et 5~0 ( Mon3anto );
The shell component of ~h~ c:ore ~hell polymer 1 usea ~ the fllm formlng compon~nt ~n ~he lmagln~
18y~ ut ~lso ful~ a vital rol~ in ~tabi~lsing the pc~ymer par~lcl~, both when ln aqueou8 ~lspe~lon ;~0 dul~ng c:oatin~ o the ~ub~rat~ an~ whsn in the im~ing la~er on the substrat~. ~rhu~ ~h~ shell ~omponen~ may unc;tion 8S a prote~;tive colloid during th~ pr4par~tion o$ c,omp~nent ( A ) ~;ing an emul~lon polymerisatlon proce~s whereby llt~le or no ~urEac~ant i~ necess~ry, Z5 or ~lterna~ively m~ olloi~l~lly ~tabili~ pol~n~r par~cl~s whic;h have been pre:~o~ e~ wlth in~u:~r'icient ~u~ac:~ant ~o ~nsure stabili~. For example, ~olystyI~erle prapared u~ing 2% by wei~ht of monome~ of so~lium lauryl ~;ulphate I s not s~orage stabl~3 n aqueous 3G ~i~per~ion, bu~ become~ ~tahle w~-en component ~ B ), n~ nn1 n~ o~ective colloid iq ~dded.
Componerlt ( 13 ) then ~ubsequently ~ct5 a~ ~ f ilm fo;cnllng ~omponen~c in the lmagin~ l~ye~.
Wh~re a t~o ~tage o~ lnver~;e core ~shell ~5 pvlymer~ ion method is lu~d a~3, or exampl~3, ~escri~ed ln Europe~n Patent Publicat~or~ No. ~384~6, ~8~8~
-B -~he h~OphOblC: ~or~ p~rti~le~ c;fln be ~tablll~d 3~y khe ~3hell whez~ ~hl~ rbox~l ~unction~l eithe~ ln ~h~
neu~r~ e~ or unrl~utrall~ tate. ~ pr~erre~
tl~ nc: c:arbox~l monome~ i~ us~d ln the co~e ~omponen~
5 a~ thl~ n ~ult in over~velopmGnt.
~ h~ 6hel~ ~omponent W~ nerally fllm P~I~m pra~er~ntl~ to ~he core aomponer)t ei~hf~r by vlrtu~
o~ it havin~ ~ lower M~q' or by virtue of, Po~ e~mple, ~ havlng been ~olubillse~ by ~ volatile ha~e ~uc:h 10 ~mmonla .
~ t 16 partlcul~rly import~nt that the shell c;om;?onen~ i~ non-water ~c~luble~ Al~hough t~e shQ1 oom~onent contains ~uoh ~roup~ ~ carbc)xyl ~n~
~llphonamido, whloh c~onfQ~ th~ r~3quir~d ~olu~lllt~ o~
15 ~;well~illty ln aqu~ou~ ~lk~llne ~olu~ion, it i~ no~
~oltl~le ~n w~t~r P~ nd, when ~a~t ~own as ~
c;omponenJc of ~he hea~ ~ens~tive layer ln acoor~an~e wlth the ~rlvention, it do~s not: ~mpart to th~t l~y~r a ~ensitl~ity ~o water. A mar~k~ deterior~tion ln the 20 ~rope~tle~ of th~se ~llm~ ocoU~ when w~te~ solubïe mat~rlaLs, lnolu~lng ~u~actants, ~re pre~ent at l~vel~
o~er ~ low threshold vslu . Amongst tlle problsms cau~d by ~he pre~ence o~ w~er~soluhle oomponen~ a~e ~e ~vllowin~:
1~ The plate~ bec:ome ~en~iti.ve to ~illyBI` con ~ct and to w~ ter O
2, The ~tora~e stabili~, e~pe.oially un~e~ humltl c30nd.i~ions, detoriorate~ marke~ly.
3. Adh~sion o~ tha coa~ing to metal substrates i~ re~ea.

4. ~he p~ durabillty of the pl~t~s de~re~s~s.
Polymeric: b~ nde~s whiCh ~lr8 water soluble, ~uc:h pc~y(vlrlyl alcohol), poly(~ yl py~olidine), poly ( et~lene oxide ), gel~ tin, ca3ein, atc ., ar~3 thus 35 unsultab~e for u~e ln thi~ invention.
~y usirlcJ core ~hell particle~ ln which a -6~ 2 hydropho~i :; co~0 i~ en~ap~ulated by th~ pre~r~d oa~boxyl unctlonal ~hel~, colloidally stable po~ r partlole~ can loe prepi~red whioh ~re vir tually fre~
w~e~ soluble component~ and thu~ do not ~u~er ~rcJrn the di~advantage~ i~o~ed ~bove, The c~oating of ~sh~ r~iatlon ~ensitive plate ~
gene~ally water re~l~t~n~ sn~ preferred that the pl~te i~ pro~uced by applyin~ ~hf3 core-~hell partlcles ~o ~he sub~tr~ts ~rom wl~lly or s~Ytantially a~ueous ~0 me~lla. How~v~r non aquso~ ~ vehicle~ and v~hlc::le~ wh:lch al~e mlx~ur~s o~ ~queou~ ~nd non~aqueou~ ~olvents m~y be u~e~l~ In ~he c~e wh~ra an aqueous vehlcle is u~e~l, lt is p~fexr~d that vol~tll~3 ba~e~ ~u~h ~ ~mmoni~ or ellnines ~r~ u6~ 0 ~olublllse ~h~ ~ell component~;.
lS The particle ~ize o~ ~e cvre-~hell particle~ 1 p~efe~bly le~ th~n 1 mic:~on and mor~ preferably les~
~han O . 5 mlc~ons~ ~he t~e~ ~ht rqtio of ~hell to core In2y ~ in ~he ~n~e 0~ rom 1: 20 to ~0 :1 ~nd p~f~:~abl~
~ ~ ~ n the ran~e o~ ~ro~ 1: 9 to 1:1.
~n An em~o~imen~ ~he ~ource o~ ~he ht ~h donsl~
r~di~tion :l~ A l~er operating in t~e ultr~ violet, Yi~ible or lnfra-~d re~ior~ o th~ spectrum. F~ed ~nd 4 ~ra-red li~ht: ~ml~tlng la~er~ ~re prefer~ed, ~
~3xample the ~emi~:or~duato~ or ~lode lase~s typlc~l vf 25 whlGh 1~ the ga'l ïium ~luminium ar~eni~l~ la~er wh~h oper~3s in th~ 7S0-870 ~m re~lon.
Th~ r~iati~n-a~rbln~ ~ubf~tanc:e may be pre~n~
ln 'i;he ~me ~a~er a~ the ~ore-~hell particle~ or lt may ~e :lncorpor~'ce~ wlthin ~he par~lcle~ th~3m~1ve~ or 30 m~y be pr~ent in a ~ep~rate ~ut ad~ ac~nt layer .
Examplas of ~;uitable laser rad~ ation abso~bin~
l3uh~anc:es ~r~ carbon bla~k and gr~phlte and phtha~ocyanln~ oconi~lm an~ uaryli~ t~pe ~y~uf~s .
3~ The radlation e~ ltive ~uhs~nce 13 presant ln an 2~8~8~

~mount Whl~,h 1~ ef ~otlYe to cause ~om~ ooql~scenc~ ~
~he partlcle~ und~r th~ fluenc~ o the hi~t~ lnten~l~y ~dl~tion. Gene~a~ly, the r~dl~tlon ~en31tive t~n~e will conetltu~e ~rom 2.0 ~o 80~, by wel~h~, S of the ~o~ti~, ~yplaul ~evelop~l ~ for sale~tlvel~ r~movln~
the non-~oale~:ced pa~t:icls~, ln the non- image ~raa~, ~re ~ueou~ ~lk~lis such ~8 ~olll~ions ~f ~th~nol~mine, }iodlum metE~ ate, ~n al~llne ~hosphate ~uch a~
~od~um phosph~te, c: ~ ~n ~lk~li m~3tal hydroxiCle ln wat~3r .
~he followirl~ Example~ illu~trate the lnventi~n.
L
41~ ~m~ of di~ti;l l~d water were plac~ ln ~ ~L
1~k equipped with stirrer, conden~er, the~mom~3ter ~nd N2 inle~/~3xlt. ~o th~3 stlrred water w~e addsd ~S . 8 om3 o~ rbos~ XL37 ( a carboa~yl funatlonal ~crylic:
re~3in ob~aine~ a~ ~ 359~ aqusou~ psr~ion ~ron~ BF
l~;oodriah I~td ) . ~han 1~ om3 of 259~ ~u~ous ~mmoniu w~sr~
a~ded. ~hen ~ c:ry~ 1 çl~3~r ~olution w~s ob~ ned, 150g of ~tyrene wer~ lCled, followed by 1. Sg o~
~mmonlum p~r~ul~ha~,e in 10 cm3 ~ tlllefl wate~. ~he rnlx~ure was maln~alned ~ 65~C with vl~orous ~tir~ing ~or a perlod o~ our hour~ to giv~ ~ ~in~l pxoduct ol~
sol$ds ~ontent 25% w/w, wi~h a partlc:le ~l~e O~ s than 0~ 5 mi~ron~ ~nd ~ ~ef~idual ntonom~ on~ent o~
0. 05~ w/w . 'rhe fln~l product was a ~ore-~hell persion c:ompose~ of p~rticles comprlsing ~ cora of polystyrene ~n~ a ~he~l of ths c~rboxylate~ ~crylic 3~) ~opol~mer~ .
1509 of Mlcrolit:h Blaol~ C~WA ( a oarbon b~aclc co~e~ wlth an ~lkall ~olubl~ ac:ryllc rasin av~ilable from ~iba Ge~y ) were ~d~ed to a n-ixtur~ o 5~0 ~n~3 ~I20 and 250 cm3 of i~opropyl alcohol wlth ~i rring . Then 10 cm3 of 25~ ~ueoug ~mmonia were e~dde~ and the mlxt~lre wa~3 ~t~rr~3d ~o~ 9 hours. rhe ~e~ lt~n~ 1ne 2~ 6 par~ 3 fiiZe c~xbon dl~pf~r;ion wa~ ~lltered th~ou~h ;~
Wh~tman GF D fllter paper ~o ~lve ~ ~olid~ ~ont~nt of 1 ~ w/~ .
~2 cm3 of the :25P6 w/w core-~hell ~ 3per~ion An~
~3.3 çJ o~ tha 1596 w/w c:arbon dlsper~on were mlx~d to~kh~r ~nd dllu~a~ wi~h 1~0 cm3 o~ l~oprop~l alc:ohol ~nd 14 . 7 ~m~ of ~i~'¢llle~ ker ~o ~lve 200 c~3 o~ ~ 7%
w/v ~lispe~ion, Thi~ wa~ coate~ on ~o ~ gr~lne~ and anodlsed alumlnlum ~ubstrate to f~lVB a coa~ w~ ht of 0. 6 ~m~ he ~eeultant ~iation-sensltlv~ plat~ w~q o~ ve~y ~oo~ appaaran~.
The plate was exposed to the mo~ul~ted ~cadlatlon ~mana~ing ~onl an ~ y o~ 100 mW di~de laser~3 output:tin~ ~t 8~0 nm to ~ ctlvsly coals3ce ~ome o ~he aore-shell parti~les to Po~m an i~a~e. ~00 mJ cm ~
s~a~ applie~ to the pl~te whlc:h wc2~ then developQA in ~n ~gueous ethanolamins ~evelope~ ( ~lectro~ol B5 o~ ~u Pont~Howson Limi~ ) to ~ive a high res~lution d~Y~lop~d imsge. Th~ pl~te wa~ bak~d ~or two mlnute~
~t ~00C: to giv~L a ~2urable p~inting plate whi~h waa ~sp~ble ~f îai~hfully reproducing more than g~, ~0 ac: ~ies .
~B~
The procedure of Exa~pl~ 1 w~ ~epeat~ ~xcep~
that ~ Nd ~AG l~er ou~puttin~ ~t 1060 nm w~x u3e~2 to e~pose the pla~e. A lmllar re ult w~; ob~ined.
X~MPLE 3 The ~or~ ~hall di~p~sion fronn Example 1 WMS mixed ~l~h a ~quar~l:lum dye t 2% of ~otal ~olid~ ) ~n~ c:o~ed ~t 0. ~gm~ Qntc~ an alum:lnlum subst~ate~ Max of the ~quarylium dye was ~OOr,m ~n met:hylene chlori~e. The plate ~as exposed, developed and heate~ as in Exampl~
1. Similar res~llt~ were o~ta~ned.

-110 cm~ of dls~l:Lled w~te~, 0,34g of ~mmonlum persulphate, an~ 2g of ~odlum ~aurylsulphate we~e 2 ~ 8 ~
_g ~
pl~c~d ln a 500 cm3 ~la~3k equlpped w:it}~ e~lrre~, c:ond~n~er, thermonle1~r, ~nd N~ inl~t nnd ou~let. Ths ~tored solution wa~ he~t~CI to ~0 C and ~n emulslor~
cor~ ting o~ ~3 cm3 ~t~7rere, ~0 cnn3 dl~t~lle~ wa~er, 5 o . 4~ ~mmonium p~r~ulphate and 1. lg ~odium l~urylsulphate wa~ addad over 3 hour~. The tsmp~rature w~ main~lned ~ b~t~een dO arl~ 85C. 30 min~ e~
tll~ la~ 0~ the ~mul 1.on ha~ been adde~ a ~ecor!a ~m~ ~ion cont~inin~ m3 butyl~ ::r~lat~, 5 c:m3 methaa~yllc: ac:id, 20 cm3 di~tilleâ wa~er 0. 5g ~odium ulphate, 0,13ç~ ~mmoniun~ per~ulphate and 1~ 8 c~m3 oc:ty~ mercaptan was adde~ over 1 hour. ~he tsmp~rature was m2~int~ined at 80 C for ~ ~u~ther 1 hou~0' On coolln~ th~ spen~lon w~s ~ilter~d th~o~l~h a Wha~m~n 15 ~F-D filter pap2r to ~emo~,re the e~all amount of ~oa~ul~ted m~terlal . Thi~ gave ~ s~l~pen~lon c: f ~olids conten~ 30 . 5~6 w~w wi~h partlcle ~l~e of less thzln 0, 3 m~ on~ and a monomer C:on~en~c of 0.03~ w~w, 15 ~m3 o~ this core-~hell di~per~lon ~nd ~ . 2 c;m3 20 of th~ 15% w/w aarbor~ per~ion ox~ Exampl~ 1 were mixed ~og~ther with 1 ~m3 of 2596 aqueous ammonl~, 7 cm3 tilled water ~n~ 18 cm3 l~opropyl aloohol to give 50 c:m3 o:E ~ 7~ w/v di~p~r~ion. This was ooat~d on~o a ~rain~ ~nd anodi~ed al~mln~um ~lbstrat~ to ~lve a ¢oat 25 w~lght o~ O . 7 gm~~ . Thi.~ gatre a ~adiat~on-sen~itlve pl~te o~ simllar proper~le~ to that de~oribecl E~x~tlllpl~ 1 . .
ES~A~1P~.E 5 ( Comp~ on ) 1, 42g of C~rboset ~SI,37 ~a~ diluted with 10 cm3 H20 ~nd 0~ 5 cn~3 of 2S9c aq~l~ou~; ammonla was add~l to ol~re the polymer . 4 . 96g o:~ Texlcote 53 . 040 ( a 50 W/W ~3c~1id8 ~tyrene homopolymer emul~ion o~ MFT 105 C
avail~b:Le flo~ Sc:ott Bader ) were added, ~ollowe~l by 3 . 5g of the carbon Clisper~i on o~ Exampl~ l . The 36 ml7~tu~e wa~ dilut~d wlth ~0 ml of isopropyl alcohol ~nd ~18~

qo;~te~ on f~ ~r~ined ~nd ano~ e~ ~luminlum ~ub~cr~te t~
ç~ve a coat wel~ht o~ 0.6 ç~m~2. A pla~e uf goo~
~ppç~ nc~3 wa~ obtained. ~h~ pl~e was lm~ed u~ln~ a la~r dioda bu~ mora than 600 mJ cm~2 was rsq~:lreq ln or~er ~o p~O~ n i~a~e whlch w~ fully in~oluhle in th d~valoper use~ in ~;x~mpla 1.
~L~ ( compt~ n ) 5 ,. 9~g of Tçxlcot~ 53-040 were Added to 8 . 25 cm3 o~
~2 ~ 3 . Sg of ~ha oarbon dl8per~0n of Examp~ e 1 were 1~ a~d~d ~ollowe~ by ~6 ml of i~opropyl ~lcohol. Thl:3 W~!18 qoat~d on e~ ~raln~ and e~no~l18e~ aluminl~lm sub~t~ate ~t C).6 ~m-~ to give ~ plat~ 0,~ sa~:eptable appearance.
How~v~r, the ~o~tln~ w~ ry poo2~1y ~dhç3re~ to the ~ub~trat~, bain~T of tl du ~y textur~ whioh was ~a~ly 1~ ~em~v~bl~ ~y, ~or examp~e, fl~g~r oontac~. Th~ plate ima~e~ &nd d~velope~ ~Wl~h ~lectrosol 85) acc~3ptabl~ Qt an ~3xpo~u~e o~ 200 m~ ( la~r dio~es, ou~putting at 8~nm) .
~T,El ~ Comp2~ison ) ilomopolymQ~ ~t~r0na ~mulsion~ w~re ~ormed by using o~ ~he followlng ~urf a~tan~s with lO0~ of st~rene u~in~
d~ e~ elddltion pro~
2 ~ so~i~m ~auryl ~ulph~ ( 4g ) b. ~mm~ni~lm la~t~ate ~ 7 ~
~5 c:~ ~o~q~um l~t~lx2~ 7, 5~ ) ~h~F;e emul~ion~; were ~o:rm~llated with Carbo~et XL37 ~nd c:arbon d.i~perslon ~o that the ~me ratlo~ of poly~tyxene emu~ ~ion: ~rbo~3t X~37: carbon disp~rsion ~ ~n ESxample 5 were obtain~d. The~e ~av~ coatin~s of 30 ~cc~ptable appear~nc~ ~ a coat weiç1ht c: f 0~ 6 gm~~ on a ç~r~lned ~r~d ano~i~ed alumitliun~ subst~te. A goo~ imags was ~bt~lne~ by dlode ~x~osur~ at 200 mJ ~ollowed by de~el~pin~7 with Ele~tro~ol 85.
The plat~ w~re ~ored ln ~ humldlty ~ablnet a~
35 30~C and 97% ~ for 1 waek. ~he pl~tes were very diffic:ult to dev~lop after this time. Th~s is in 2 ~

oontr~t to ~he platQ of Examp~ e 1 ~hlch, ~r lma~in~
~ 200 mJ ~nd ~toring for ~our we~ks ln ~ h~lm~dl~y a~inet, could be ~eadily â~veloped with E~ ec~ro~ol ~5 .
~AMpr,~
U~.~ng an identlcal prooed~re to ~hat desc~lbe~ ~ n Example 1, ~ ~tyrene-b-lty~ acryl~te c:ore-shell polyer was fo~nled ~ 5 ~ of the Rtyrene was repl~ced by 5 g of butyl ~cryl~'ce. The ~e~ult~ srere ~lmll~r to thos~
obta~ne~ ln E~xamp.ïa 1.

In a S00 ml fla~k e~uippe~ as ln Ex~mple 1, 43 ml 0~ ~ar~c)set XL37 ( 3S~ w/w Boll ds ) we~e aaded to ~40 ml n~ ïed w~er. ~he r~in W~ di~olved by ~lng ~ ml of 25~ aqu~ou3 ~mmoni~ ~nd he~tlng to 50 n C ~
lS 0.75 ~ of ~mmonlum per~ulph~e wa~ ~h~n ~d~ed to the mlxtura, followed by 3.75 ~ ~f ~ mi~t~re of 37.5 g of B~yrens ~nd 37.5 ~ of ~b~ylonl~rll~. Aft~r a fu~ther 10 mlnut~ he remain~er o~ the monom~r mixt~r~ was ~dded over ~ perlod o~ ~wo hours. The temper~ture wa~
20 main~ained ~ 60 ~ ~o~ ~ fu~the~ ~our ho~r~ ~nd the product wa~ then filte~e~ ~ givOE ~ ~0.5~
dl~p~r~ion of ver~ ~ne partl~le ~iZH. Thls perfo~med ~n ~ ~lmil~r f~hion to the m~rl~l ~e~crib~ l.n ~x~nple 1.
E~ Qo~
8g ~f polyeth~ne (S3g4-~5, ~iamond Sh~m~o~k), 2g N~t.tonal 28-~9-30 (a ~e~poi~m~r of vlnyl acetate, vlnyl v~r~tate an~ crotonlc a~id, a~ailable ~rom Natl~nal Adhe lves ~ Ra~lnS L~d), an~ l.$g Mi~ollth Bla~k CTA
(~ predi~pe~se~ a~rbon avallahle from Ctba ~elgy) were mlll~d ln ~ mlxtu~a o~ tolu~ne, me~hyl ethyl ketone and methoxy propanol for ten hour~. ~ disper~ion of the polyethyl~n~ ~nd c~rbon ln ~ ~o~utlon of tha al~all ~oluhl~. re~in w~ ob~ln~d~ ~hi~ wa3 co~ted on ~
~r~i.ne~ and anodi~ed aluminlum suhstrate at 1 gm~~ to ~iv~ ~ pl~e ~f goo~ appearanceO Th~ plate im~d well ~8~3~

~-lZ-a~c ~00 m~ bu~ wa~ ~o prs~ux~ ~enYltive th~t developmen~ W~ ifPicul~.

Claims

1. A radiation sensitive plate which comprises a substrate coated with (i) one or more layers each comprising core-shell particles each of which comprises a water-insoluble heat softenable core component (A) and a shell component (B) which is soluble or swellable in aqueous alkaline medium, and (ii) a substance capable of strongly absorbing radiation and transferring the energy thus obtained as heat to the core-shell particles so that at least partial coalescence of the particles occurs.

2. A radiation sensitive plate as claimed in claim 1 wherein the substrate is of metal or plastics material.

3. A radiation sensitive plate as claimed in claim 1 wherein the core component isan oleophilic film forming addition polymer, polyester, polyamide or polysurethane.

4. A radiation sensitive plate as claimed in claim 3 wherein the addition polymer is derived from styrene, a substituted styrene, an ester of (meth) acrylic acid, a vinyl halide, (meth) acrylonitrile, a vinyl ester or a polyether.

5. A radiation sensitive plate as claimed in claim 1 wherein the shell component is a polymer containing carboxylic acid or sulphonamido groups.

6. A radiation sensitive plate as claimed in claim 5 wherein the shell component is a copolymer derived from one or more ethylenically unsatureated acids and one or more of styrene, a substituted styrene, an ester of (meth) acrylic acid, (meth) acrylonitrile or vinyl acetate; a dicarboxylic half ester of a hydroxy group containing polymer; or an alkyl or aralkyl half ester of a copolymer of maleic anhydride with styrene or an alkyl vinyl ether.

7. A radiation sensitive plate as claimed in claim 1 wherein the radiation-absorbing substance is present within said core-shell particles.

8. A radiation sensitive plate as claimed in claim 1 wherein the radiation-absorbing substance is carbon black graphite or a phthalocyanine, croconium or squarylium dyestuff.

9. A method of forming an image which comprises:-(a) providing a radiation-sensitive plate comprising:-a substrate provided with a coating comprising (i) one or more layers each comprising core-shell particles each of which comprises a water-insoluble heat-softenable component (A) and a shell component (B) which is soluble or swellable in aqueous alkaline medium, and (ii) a substance capable of strongly absorbing radiation and transferring the energy thus obtained as heat to the core-shell particles so that at least parital coalescence of the particles occurs, (b) image-wise exposing the radiation-sensitive plate to a beam of high intensity radiation, by directing the radiation at sequential areas of the coating and modulating the radiation so that the particles in the coating are selectively at least partially coalesced, and (c) developing the image-wise exposed plate with aqueous alkaline medium to selectively remove the areas containing the non-colesced particles and leave an image on the substrate resulting from the at least partially coalesced particles.

10. A method according to claim 9 wherein the radiation is red or infra-red laser light.