Note: Descriptions are shown in the official language in which they were submitted.
217361~
WO 9S/10563 PCT/GB94/0216~
Polvmeric Film
, This invention relates to a polymeric film and in particular to a matt polyester
film.
Poly")alic and particulariy polyester, films have been used in the production of a
Ill&gllelic card such as a credit card, and in particular a "pre-paid card" eg a telephone
card and an "intelligent card", which is for exa., 'e capable of storing iuro,,,,dlion
relating to a number of rillallc;al l, dns&ctions. A polyc_tcr film for use in a magnetic
card is plt:rt,dbly opaque with the surface thereof exl,ibili,)g a matt finish. The matt
finish is required to reduce -~rec~ light f~tleotion from the surface of a ".ag"~lic card.
Opaque polye~ter films have been traditionally produced by i"co,~uo, dling a white
pigment, such as titanium dioxide into the film. Unfortunately, for certain a, ~ tions
the arort:",entioned polycrtcrfilms may possess an ulla~. s~ ''e surface gloss.
During the normal film making process waste polye_~er film is recycled or
,~ula;..,ed which can result in incif~ased colour, particulariy yellow ro""&lion in the
15 resultant film. Thus there is also a con.."~ ial requirement for an opaque polyeotcr
film, especially for use in a ."ag..elic card, to possess improved ~i' )ess particulariy
as regards reduced y~"~ ...leS5 thereof.
We have now devised a pol3re~,tdr film suitable for use in a .na~,,elic card which
reduces or substantially ove.co."es at least one of the &ru,~,.,e"lioned p,.b'e "s.
Accordingly, the present invention provides a matt poly.,.e(ic film co""~ i"g 74to 99% by weight of polye_~ur, 1 to 20% by weight of titanium dioxide pal li-.le-~ having a
volume distributed median particle diar"eler in the range from 0.1 to 2.0 um and 0.1 to
6% by weight of mica p&. ~ s having a volume distributed median pardcie iid",eler in
the range from 3 to 40 ~m.
The invention also provides a method of producing a matt poly."eric film
COIll,oriaillg 74 to 99% by weight of polye_ter 1 to 20% by weight of titanium dioxide
p< '?S having a volume di~t,ibulad median particle did",el~r in the range from 0.1 to
2.0 ,um and 0.1 to 6% by weight of mica p&l~ es having a volume distributed median
particle did,"el~r in the range from 3 to 40 um.
The invention further provides a "&g"eUc card co""~ i"g a Ill&yllelic layer anda matt poly."eric film which co,"~ .es 74 to 99% by weight of polye_ter, 1 to 20% by
weight of titanium dioxide p&l';''~S having a volume distributed median particledia",etdr in the range from 0.1 to 2.0 ~um and 0.1 to 6% by weight of mica palli~les
having a volume distributed median particle did",eter in the range from 3 to 40 l~m.
The polymeric film is a self-s~",po,ling film, ie a self-sl.~upo,ling structure capable
of i"depender,l exi;,Lence in the absence of a su~ po,li"g base.
WO 95/10563 ?~3~ pcrlGB94lo2l65
The polymeric film accordi"g to the invention may be formed frorn any synthetic,film-forming polyester material. Suitable lhèllllOp!~ ics polyester ",~le,ials include a
synthetic linear polye_~è, which may be ot - ~ed by condensi"g one or more
dicali oxylio. acids ortheir lower alkyl (up to 6 carbon atoms) diesters, eg lelèphll
acid, i~opl,ll,-' - acid, phthalic acid, 2,5- 2,6- or 2,7-na~JhU '-neuica,L,uxylic acid,
succinic acid, sebacic acid, adipic acid, azelaic acid, 4,4'-diphe"~ldica,i oxyl; acid,
hexal,~dlul~.Gphll,alic acid or 1 ,2-bis~p-cd,bdx~ heoox~ell~ane (optionally with a
l"onoc~,~ù~i ~ acid, such as pivalic acid) with one or more glycols, palticularly.
aliphatic glycols, eg eU,~lene glycol, 1,3-p,upanediol, 1 ,4-butanediol, neûpe,n~l glycol
and 1 ,4-cJ_lohexanedil.,eU,anol. A poly~ lene te,e~Jhdl,aldte or polyetl"l~lenenapl,lhalate film is plefelled. A polyethylene terl:plltl,aldle film is particularly plerelr~d,
e~l)ecr ~lly such a film which has been biaxially oriented by sequential stretching in two
mutually perpendicular di.e-,1iùns, typically at a It:lllpeldlule in the range 70 to 125,
and p,erê,dbly heat set, typically at a lé""oe,~ture ~n the range 150 to 250-, for
exd", 'o as desc,il,èd in British patent 838708.
The amount of the polyes~er present in the poly."e,i~, fllm according to the
invention is pr~re,dbly in the range from 78 to 96% by weight, more p,eré,di,ly from
82.5 to 92%, and especially from 85 to 89.5% by weight based upon the total weight of
the cG""~one.,b present in the poly."enc film.
The poly."ênc film according to the invention may be uniaxially oriented, but isp, t:re, dbly biaxially oriented by drawing in two mutually p~, pandhi.llar directions in the
plane of the film to achieve a s;~ r~t~ry GOIl.' ~alion of Illeclldl ---' and physical
plupe~lies. ro""~lion of the film may be effected by any process known in the art for
producing an oriented polye~.ter film, for exa" r ~ e a tubular or flat film process.
In a tubular process sim~ " ~eous biaxial one"lalion may be effected by
extruding a Ulellllop!~ s polyeotcrtube which is s~hsequently quenched, lel,ealed
and then e,~,anded by intemal gas pressure to induce transverse one"l~lion, and
vr~ ., at a rate which will induce longitudinal orienl~lion.
In the uler~lled flat film process a film-forming polye_tcr is extruded through a
slot die and rapidly quenched upon a chilled casting drum to ensure that the polymer is
quenched to the &Illol~Jllous state. O,ienl~lion is then effected by stretching the
quenched extrudate in at least one ~ire~ion st a telllpeldlure above the glass tl~nsili
te."perdt.lre of the polyestcr. Sequential orie,l~dlion may be effected by allel-,ll;ng a
flat, quênchêd extrudatê firstly in one dile~,Lion, usually the longitudinal di,èc~ion, ie the
forward di.e~ion through the film stretching ~.,a~i.ine, and then in the transverse
di.é~Lidn. Forward ~llel~hing of the extrudate is conveniently effected over a set of
WO 95/10563 21 7 3 ~ I PCT/GB94/02165
rotating rolls or between two pairs of nip rolls, transverse allt:lcll;ng then being effe`cted
in a stenter appardlus. Slrelul,illg is effected to an extent dl:le"";.,ed by the nature of
the film-forming polyes'er, for example a linear polyester is usually al,~tcl,ed so that
the dil"ension of the oriented polycstcr film is from 2.5 to 4.5 times its original
5 .lil"ension in the, or each dil~c~ion of all~l~;l,ing.
A al,~lched film may be, and pl~reldbly is, dil"ehaiondlly ~'-' ' e~ by
heat-setting underdi.llensional restraint at a le",peldlure above the glass l,~nailion
le",pert,l,lre of the film-fomming poly~,~.ler but below the melting le"r~i~e~t~lure thereof, to
induce crystallisation of the polyester.
The poly",e~ic film accG,.li"g to the invention is p,~re,~bly opaque and
pltJrerdbly exhibits a T,dns"l;~ion Optical Density (TOD) (Macbeth Dena;~ulllel~:" type
TD 902; l,~":.-";~aion mode) in the range from 0.4 to 1.75, more plt5~el~bly from 0.6 to
1.6, e~pec:--"y from 0.8 to 1.5, and particulariy from 0.9 to 1.4. The aror~l"er,lioned
TOD ranges are particularly ~p~ ''s to a 190 ~m thick polymeric film.
The surface of a poly",eric fllm according to the invention is matt and pr~rerdbly
exhibits a 60 gloss value, measured as herein des.;,ibed, of less than 60%, more
~,dbly less than 50%, especially in the range from 5% to 40%, and particularly from
1 5% to 35%.
The poly",e(ic film according to the invention is white and suitably exhibits a
~;,;teness index, measured as herein desc,il,ed, of greaterthan 80, p,~rer~ly greater
than 85, more p,t;rerably greater 90, especially greaterthan 95, and particularly greater
than 100 units.
The polyl"eric film accol.li"g to the invention p,~rer~ly exhibits a ye'l-l/.,eaa
index, measured as herein desu, il,ed, of less than or equal to 3, more pf~rt:rably less
than or equal to 1, especially less than or equal to -1, and partlcuiarly less than or equal
to -3.
The poly."eric film acco,di.lg to the invention plt:reldbly exhibits a root meansquare surface roughness (Rq), measured as herein descl ibed, in the range from 200
to 1500 nm, more pfer~lably from 400 to 1200 nm, and esl,e~ ~"y from 500 to 1000nm. The poly."e, ic film rj,~r~rdbly has a mean surface slope (~q - root mean square
surface slope of the profile throughout the asaeas",er,l length), measured as herein
desclibed, of greaterthan 2, more ~ r~,ably greaterthan 3, and especr~"y greater
than 4.
The individual or primary titanium dioxide pdl~; 'es suitably have a mean crystal
size, as determined by electron microscopy, in the range from 0.05 to 0.4 ,um,
plerérdbly from 0.1 to 0.2 ,um, and more pn:rer~bly of app,uAil.,dlely 0.15 ,lm. In a
WO 9SilOS63 ~ PCTIGB94/02165 --
pr~r~, I ed e" Ibocii, "enl of the invention the primary titanium dioxide pal Lir ' ~ s agy, t:gd1e
to form clusters or agglG",6,d1es cg",prising a plurality of titanium dioxide particles.
The ayy~dgd1ion process of the primary titanium dioxide pali- ~f S may take place
during the actual sy.,ll,esis of the titanium dioxide and/or during the polyester and film
5 making process.
The agy,~galed titanium dioxide filler ~"~r~;rably has a volume distributed
median particle did",eler (equivalent sphe,ical clia",~ldr co"espori-l:ng to 50% of the
volume of all the pallicles read on the cumulative distribution curve relating volume %
to the didllleter of the pali~ often referred to as the "D(v 0.5)" value) as
d~lt;l " ,ed by laser dirr, d~;tion of from 0.3 to 1.5 ;um more ~un~rel dbly from 0.4 to 1.2
~m and particulariy from 0.5 to 0.9 ,um.
The size distribution of the titanium dioxide pa,'; '~s is also an illl~oolldlltpdldllleldr for e~d",~ ' the p,-:aence of exccssively large particles can result in the
film exhibiting ullai~ tly 'apechle' ie where the -.,esence of filler d~ur~gdles in the film
can be dis~",ed with the naked eye. It is ~ re"dd that none of the titanium dioxide
particles inco, uGl dldd into the poly."eric film should have an actual particle size
exceeding 50 IJm. ra. t~ lr s exceeding such a size may be removed by sieving
pluc6saes which are icnown in the art. I IDw_./cr sieving ope,~lions are not always
totally succsssful in eliminating all pdli- '~5 greaterthan a chosen size. In practice
1hen~ro,~ the size of 99.9% by number of the titanium dioxide pa~ .5es should not
exceed 50 l~m pl~rerdbly should not exceed 30 um and more p,t:rera~ly should notexceed 20 um. Plere,dl,ly at least 90% more pl~rt:ldbly at least 95% of the titanium
dioxide filler pdl ~; ~e s are within the range of the volume distributed median particle
diameter ~ 0.5 um, and particularly ~ 0.3 um.
The amount of titanium dioxide incoluoldldd into the polymeric film deaildbl~
should be in the range from 3 to 17% by weight, more plt:relcbly from 6 to 14% by
weight and ~spec LIly from 8 to 12% by weight based upon the total weight of the pone~lta present in the poly."e,ic fllm.
The titanium dioxide pa,ii ~ ~s may be of anatase or rutile crystal form. The
titanium dioxide p&llicles plt7r~rdbly co",pnse a major portion of anatase more
plGre,ably at least 80% by weight, particularly at least 80%, and espec; -'~y
app,u~i,,,al~ ly 100% by weight of anatase. The pal1i-;!ts can be p,~paled by aLandald
procedures such as using the chloride process or p,e:r~rdbly by the sulphate process.
In one e",bodi."6r,1 of the invention the titanium dioxide pad,1icles are coated3~ p,~re,dblywithi~u~yall oxidessuchasaluminium silicon zinc ",adgnesiumor
mixtures thereof. Pl~re~d~ly the coating ad~li1ionally Colll~liadS an organic compound
~ WO 95tlO563 1 7~ PCT/GB94102l65
such as fatty acids and p.creldbly all~anols, suitably having from 8 to 30, preferabl~
from 12 to 24 carbon atoms. Polydio,yano~ '~ )es or polyoryanohyd-ugen ' : nes,
such as polydimethyls;loxdne or poly."ell,ylh~,d,ugen~ ' :nrle are suitable organic
compounds.
The coating is applied to the titanium dioxide palli-,les in aqu~ous suspension.The inoryan;c oxides are p,e~;pit;~l~d in aqueouC suapenaion from water-soluble
compounds such as sodium aluminate, aluminium sulphate, aluminium l-~ xide,
aluminium nitrate, silicic acid or sodium silicate.
The mica p&.li~,les p.crc,dbly have a volume di~ributed median particle
di&",eler, as her~,i"befo,t: defined, as delel ",i"ed by laser dirr~d~ tion, in the range from
8 to 30 ~m, more prercrdbly in the range from 11 to 25 ~m, and especially from 14 to
20 I-m.
As regards particle size distribution, the mica p&lliole~ n~r~l~bly have a 90th
percentile in the volume distributed cumulative particle size distribution of greater than
2 ~m, more prercldLly greater than 4 ~m, and especially greater than 5 ~um. In
addition, the mica particles prefc,dbly have a 1ûth percentile in the volume distributed
cumulative particle size distribution of less than 55 ~um, more p~t:rcr~bly less than 40
,um, and e~l~e~i "y less than 30 l~m.
The ratio, of p(creldbly at least 70%, more pl~:fcldbly at least 80%, and
particularly at least 90% by number, of the maximum width to the minimum width of the
mica p.l,'; 'es is p.e:rcrdbly less than 4:1, more plcrc-dbly less than 2:1, and particularly
less than 1.5:1.
In a p.crc..ed e.nbod;,..c..l of the invention the mica pa.~; les suitably have a
Ih- ' ~ess in the range from apl"oxi...all,ly û.1 to û.6 I-m. The average ll~icl~,.ess of the
mica particles is preferably in the range from 0.2 to 0.5 ,um, more p,efcr~bly from 0.3 to
0.411m.
In orderto obtain the advdnl;~souc ~,.o~,c.lies of the present invention the
conce..l.t,lion of mica p&lli~,les present in the pol~,..enc film should be in the range
from 0.1 to 6.û% by weight, plcfcrdbly 1.0 to 5.0% by weight, particulariy 2.0 to 3.5%
by wei~ht, and especially 2.5 to 3.0% by weight, based upon the total weight of the
~"-ponc,lts present in the poly...eric film.
Particle size of the titanium dioxide and mica pa. li-,les may be measured by
electron mic.uscope, coulter counter, se~i,nc.,l~tion analysis and static or dynamic light
s~llefi.,g. Te.~ es based on laser light dirr,~,lion are plt:rellcd. The median
3s particle size may be dele,." ~ed by plotting a cumulative distribution curve lcp-cse--li"g
the pe,ucr.ldge of particle volume below chosen particle sizes and measuring the 5ûth
WO 95/10563 7,~G~ PCT/GB94/02165 ~
percentile. The volume distributed median particle dia",dler of the filler pa, li '~ s is`
suitably measured using a Malvem Instruments Maale,ai~dr MS 15 Particle Sizer after
di~,uelaillg the filler in ell,~lene glycol in a high shear (eg Chemcoll) mixer. For
non-spl)ericdl pdllicles, such as planar pdlliulcs like mica, a s~uherical average
5 equivalent ~ia."t:ldr is r ~ t~r~
The titanium dioxide and mica pa, L Y - s may be added to the polyester film or
polyester film-fomming material at any point in the film manufacturing process prior to
the extrusion of the poly~ ar. For C~dlll, '9, the titanium dioxide and/or mica palLiclEs
may be added during IllORGllld( transfer or in the autoclave, although it is p,~:re"ed to
10 inco".G,dle the pdl~ ; as a glycol ~;spe,:ion during the ealt:rificdlion reaction stage
of the polycstcr s~"ll ,eaia. Altematively, the titanium dioxide and/or mica pdl li-.;lES may
be added as a dry powder into the polymer melt via a twin-screw extruder or by
Il Idalt:l IJdlCI~ cl ll~C ~ i ~"r.
The ratio by weight of titanium dioxide pdl ;- le s to mica pdl li-,le~s present in a
polymeric film acGo,di"g to the invention is pl~re,dl,ly in the range from 10:1 to 1:1,
more p,erdrdbly from 6:1 to 2:1, and especially from 5:1 to 3:1.
In a plerelldd embodiment of the invention, the poly."eiic film co".prises an
optical brtyl,lener. An optical b,i~Jl,lener may be included at any stage of the poly",er
or poly."~, ic film production. For a poly_~ter, it is p.~rell~:d to add the optical
bliylltdner to the glycol, or altematively by s~ ~hserl(lent addition to the polyestcr prior to
the ro""dlion of the poly."eriG film, eg by i";~ :icn during extrusion. The optical
briyl,ldner is pl~re,dbly added in a",ou"ls of from 50 to 1500 ppm, more p~ere,dbly
from 200 to 1000 ppm, and especially from 400 to 600 ppm by weight based upon the
weight of poly."enc material in the film. Suitable optical b(i~ enera include those
available co~"",e~ially underthetrade names "Uvitex" MES, "Uvitex" OB, ul ~ucop~EGM and; L.&:lloblil~'- OB-1.
The Ihiulhleaa of the polymeric film acc~rJi.,y to the invention is prere,dbly in the
range from 12 to 400 ,um, more plt;rt;ld~ly from 50 to 350 ,um, especially from 150 to
250 ~um, and particularly from 160 to 220 ,um.
A poly",e,ic film ac~,.ling to the invention may be coated on one or both
surfaces with one or more additional primer, coating, ink, lacquer""ay"t;lic and/or
metal layers, for example to fomm a lalll;.ldle or coll",Gsile which exhibits improved
,u,upe,lies, such as alllialdlic, adl,esion ,blulllulillg or release, co",pdrt d with the
cG",ponenlIlldlel;.31s.
A pl ~rt:l l ed adhesion pl ul l loli, ,g coating layer co~ ul iaes an acrylic resin. The
acrylic resin is p,~r~,ably ll,e""osel and plt:~elably co",prises at least one monomer
WO9S/10563 Z1 73Gl ¦ PCTIGB94/02165
derived from an ester of acrylic acid and/or an ester of l,-ell,acrrlic acid, and/or
derivatives thereof. In a pr~rel,ed elllbGdi~llehl of the invention, the acrylic resin
~Ill,l~lises greater than 50 mole %, plt:rerdblr less than 98 mole %, more plt rt rdbly
J from 60 to 97 mole %, especially from 70 to 96 mole %, and particularly from 80 to 94
5 mole % of at least one l,-onGr"ar derived from an ester of acrylic acid and/or an ester
of ~,.ell.acrr~ic acid, and/or derivatives thereof. A p.~ren~d acrylic resin for use in the
present invention prereldbly cG,..prises an alkyl ester of acrylic and/or ",~II,ac(ylic acid
where the alkyl group contains up to ten carbon atoms such as methyl, ethyl, n-propyl,
i50plup~rl, n-butyl, isobutyl, terbutyl, hexyl, 2-elh~ yl, heptyl, and n-octyl. Poly",er:,
10 derived from an alkyl acrylate, forexample ethyl acrylate and butyl acrylate, togt:ll.er
with an alkyl ...e:ll.au,rlate are ple~llcd. Foly."e,~ co---,u.isiny ethyl acrylate and
methyl ...ell.&c.ylate are particularly p~r~l~cd. The acrylate ...ono...er is pleféldbly
present in a prupG,lion in the range 30 to 65 mole %, and the ."t:ll.&cfylala ",onG",er is
p,arerdbly present in a plupGIlion in the range of 20 to 60 mole %.
A p~rt:--ad acrylic resin, derived from 3 I-.onol.. e,~ co.. ,u.i:.es 35 to 60 mole %
of ethyl acrylate/ 30 to 55 mole % of methyl 1~ ll,ac,~ldla/2 to 20 mole % of ac.~ e
or ",~:ll,ac,yld.uide, and especially cor,.p.iai.,g &,l~pluAillldl~ molar ~JIupGlliGns 46146/8%
.~spe~ively of ethyl acrylate/methyl ~..~I.ac.rl-4t~,/&c.yld.. ie omlleUI&clyl.,.llile, the
latter polymer being particularly effective when tl,~,.,.osel - for example, in the
20 p.asence of about 25 weight % of a methylated melamine-fu....~lde~,yde resin.A plcrt,l-l:d acrylic resin, derived from 4 ..onu-..e.~ co",,urisas a copoly."er
c~...pri:,i.,g cG--.onol"e,a (a) 35 to 40 mole % alkyl acrylate, (b) 35 to 40 mole % alkyl
",e1hacrylate, (c) 10 to 15 mole % of a ",onG..,er co"ta;. ~9 a free ca-L,ù,~yl group, and
(d) 15 to 20 mole % of a --onou-er cG-,la;,-ing sulphonic acid and/or a salt thereof.
25 Ethyl acrylate is a particuiarly plt:rtll~d ",onon,e( (a) and methyl ",eU-ac-~lldle is a
particularly pler~ d ",ono...er (b). ~1,,nGI~er (c) containing a free calLo~yl group, ie a
cdli uAyl group other than those involved in the poly.nenadlion reaction by which the
copoly..,er is formed, suitably COIll,uri:~ds a copoly...er '~e unsaturated ca,~u.cy~.c
acid, and is p,~:re.dbly sele~æd from acrylic acid, ..,~:II-acrylic acid, maleic acid, and/or
30 itaconic acid; with acrylic acid and itaconic acid being particulariy p~re..ed. The
sul~ 'nonic acid ~onG~ar (d) is p,~rt:rdL,ly aror"dlic and may be present as the free acid
and/or a salt thereof, for U~dll, ~e as the a"....or ~m, sllhstitllt~d a",.,.onium, or an
alkali metal, such as lithium, sodium or pot~ciurn, salt. The sulpllohdld group does
not pdllic~;~Jdla in the poly",er~isdLion reaction by which the a~ll,en -.l copolymer resin is
35 fommed. The sulphonic acid ",ono",er is prèrt:,dl~ly p-styrene sulphonic acid and/or a
salt thereof.
Wo 95/10563 ~ 6 ~ ~ PCT/GB94/0216
Prior to the depo~;tion of a coating medium onto the polymeric fllm according tothe invention, the eYI~osed surface thereof may, if desired, be subjected to a cl~e",:~~'
or physical surface-modifying l,edl",e"l to improve the bond b~ en that surface and
the s~hsequently applied coating layer. A p~r~:lled L.~d~ l.L is corona disol,a.ue,
which may be effected in air at al",Ga~.heric pressure with conver,lional equipment
using a high frequency, high voltage generdlor, p.~rt.dbly having a power output of
from 1 to 20 kw at a polenlial of 1 to 100 kv. D;s~,l.d,ue is conven e .lly accG",r' hed
by passing the film over a dielectric suppolt roller at the d;~ol~d~ya station at a linear
speed plareldbly of 1.0 to 500 m per minute. The (Jiscl~d,ya 1~,t,udes may be
positioned 0.1 to 10.0 mm from the moving film surface. Altematively, the polymefic
film surface may be p,et,~:dled with an agent known in the art to have a solvent or
swelling action on the polymer layer. C~dlll, 'S of such agents which sre particularly
suitable for the In~dl,.,~"l of a poly~ ar film surface include a h~logendled phenol
.li~solved in a cG,.,...on organic solvent, eg a solution of p-chloro-m-cresol,
2,4-dicl.!~ uphenol, 2,4,5- or2,4,6- Iri.il,'c u~ enol or 1 cl~'crult5sGl~ lol in acetone or
",ell.anol.
The coating medium may be applied to an already ofiented polymeric film, but
a~ 'ion of the coating medium is pler~:ldL/ly effected before or dufing the all~l~l.;ng
op~. ali~n.
In particular, it is p.erel,c:d that the coating medium should be applied to thesurface of a poly".enc film b, :-een the two stages (longitudinal and transverse) of a
II,e",~oplc!~liGs film biaxial stretching operdlion. Such a sequence of all~LI.lling and
coating is especially p~a~"~d for the production of a coated poly...eric fllm colnpria;ng
a linear polyEstcr, which is ~ule:fela~ly firstly all~L~;lled in the longitudinal ~ acLion over
a sefies of rotating rollers, coated with the coating layer, and then aLl c:lched
tr~nsversely in a stenter oven, pl~felably ~ w~ d by heat settlng.
In one embodiment of the invention the poly."e,ic film ad~itionally co""u,ises ahcat ~e'`l''l`'Q layer. The hcat ser'Ahle layershould be capable of forming a hcat scal
bond to itself and/orto the substrate, by heating to soften the poly."e(ic matefiai of the
heat-se-'-''e layer and apply.ng pressure without sonan;.,g or melting the polyester
material of the substrate layer.
The heat se~ 'e layer suitably co",p,ises a poly~stcr resin, particulariy a
copolycster resin derived from one or more dibasic alulllalic ~ILJo~c acids, such as
~e.~ l.ll -"., acid, isopl,lha"~ acid and hexahydluL~ pl,Ll,-''c acid, and one or more
glycols, such as ethylene glycol, diethylene glycol, triethylene glycol and neopentyl
glycol. Typical COpOIy~ ,a which provide 5;~ r~ ~ory heat-se~l~h'e proper~ies are
WO95/10563 1 73~ PCT/GB94102165
those of ethylene lele~JhLlldldld and ethylene isopl~ll,ala~e, e~peci~ "y in the molar`ratios
of from 50 to 90 mole % ethylene lelephlhaldle and c~lleapondingly from 50 to 10mole % eulilene iso~hlll&ldle. Plerelled copolyeste.a c~."plise from 65 to 85 mole %
ethylene tele~hlllaldle and from 35 to 15 mole % eUI~1lel)e isophulaldle~ and especially
5 a copolye~tcr of about 82 mole % ethylene terepl,ll,aldte and about 18 mole %
ell,~lene isophU,sldle.
A poly.neric film acco,.ling to the invention, particularly when coated with a
hoat s~ ''e layer, may be used to produce credit or icie,.~ c~ion cards. In particular,
the hcat se -' - ~'e layer may be printed thereon with ink or dye from convenlional
printing sources, for eAa", 'e in a themmal transfer printing process. The printed film
may be hcat scalcd to another poly."e,ic film, prereld~ly a polyester, more p,cre,ably a
llanapdler,l film which can act as a protective cover for the printed layer.
A Ill&yllelic card, as hel~;nberole desc,ibed, pr~rcld~ly co",~u,iaes the r~IIDW;.I9
layers, in order, (i) a Ill&yllclic layer, for storing the relevant i~rul'''dlion~ (ii) a
poly."eric film layer, according to the present invention, and (iii) a gldpll ~ ~ layer or
printing layer, which provides visual i"ro""dlion, such as the type of card, owner etc. A
range of convenliùndl binders may be used forthe Illay"d~ic coating Illalelials, which
are well-known to the man skilled in the art. A wide range of inks and lacquers may be
used in the ~,aph Iayer, such as allueous and organic solvent-based ~ elials,
particulariy electron beam- and UV-curable inks.
Poly."er~c films according to the invention may be used in other ~ppl~ lons
where a white opaque fllm exl,ibiling a matt surface is required, such as in
pholuu,d,~h;c a, r';c~'ions, non-",ay"elic inroll"dlion storage and as writing Illalclidls.
In this speciric-~;ùn the r.'l~w;.,g test IllelllGds have been used to determinecertain I~IOpellieS of the poly."e,ic film:
(i) T,dna,. ~n ODtical Densitv ~TOD)
TOD of the film was measured using a ~o~ ::, Dena;~u,,.cler TD 902 (oblai.-ed
from Dent and Woods Ltd, B2sin", :' , UK) in lldllal. n mode.
(ii) Matt Surface ProPertv
The 60 gloss value of the film surface was measured using a Dr Lange
R~ne~;tu,,,èlcr RB3 (ob~a;ned from Dr Bruno Lange, GmbH, nu~sc~ldG~r~ Germany)
based on the p,i".i,!'es desc,ibed in ASTM D 523.
(iii) Whi"ncsa Index and Yell_J~r"ess Index
The whiteness index and y~ .,eas index of the film was measured using a
Colorgard System 2000, 1~ del/~5 (manufactured by Pacific S~ ~nliric) based on the
~u,i. r'~S described in ASTM D 313.
WO gs/iO563 2 ~ 3 ~ 1 4 PCT/GB94/02165
(iv) Surface Rou~hness
The film surface root mean square roughness (Rq) and mean surface slope (~q)
were measured using a RankTaylor-Hobson Talysurf 10 (I ~icester UK) e" oy;.,g a
cut-off length of 0.25 mm.
The invention is illustrated by ,kfe,ence to the roll ~i.,g exd", r ~r.
FY~rnDIe 1
Poly~ll ,yle.1e lel ep~lU ~aldle poly" ,er co" I,Oriail)9 10% by weight of anatase
titanium dioxide having a volume distributed median particle dia",eler of 0.7 jlm 3.5%
by weight of mica (SX300 Mica s~ . r ~i~ d by Micl ur" ,e Minerals Ltd Derby UK) of
volurne distributed median particle dia",èler of 18 ;~m and 460 ppm of optical
brightener (~aalo~,ile OB1 Cdal",an Kodak) was extruded through a film-forming die
onto a water cooled rotating quen~ 9 drum to yield an alllGI~JIIOUS cast cû,,,posile
extrudate. The cast extrudate was heated to a te",pe,dl-lre of about 80-C and then
al,~lcl,ed longitudinally at a forward draw ratio of 3.2:1. The poly."eric film was passed
into a stenter oven where the film was all elched in the ~ d:re- lion to
ap~u,u,~i",~ly 3.4 times its original din.ensions. The biaxially allel~:l,ed polymeric film
was heat set at a telllpe.~lure of about 225-C. Final film thickness was appruAi---~ely
188 j~m.
The polymeric film was s~ ~ o ~ to the test procedures descni~ed herein and
e ,~ h ~~ the rO ~ ng plupellies.
(i) Trdna", ~ Optical Density (TOD) = 1.0
(ii) 60- gloss value = 31%
(iii) Whiteness Index = 98 units
Yo ~l"less Index = -3.0 units
(iv) Root mean square roughness (Rq) = 570 nm
Mean surface slope (~q) = 4.3
~ '8 2
The procedure of i_Xdll, ' 1 was ~epedled except that the optical i;~(iyl,lener was
omitted. The polymeric film was subjected to the test procedures descni~ed herein and
exl.il,ited the followin~ plupellies.
(i) T,d"s" n Optical Density (TOD) = 1.0
(ii) 60- gloss value = 31%
(iii) Whiteness Index = 84 units
Y~ ~.,ess Index = 1.5 units
(iv) Root mean square roughness (Rq) = 590 nm
Mean surface slope (~q) = 4.4
~ wogs/ios63 ~36~ 11 ~ PCT/GB94/02165 ~
ExamPle 3
This is a co""oar~ e e~" rl~ not accor~i"s to the invention. The procedure of
i-xample 1 was I epe~led except that the mica was omitted. The polymeric film was
subjected to the test procedures des~i,ibed herein and e,cl,il-iled the following
5 ,~, upel lies.
(i) T,a"~",;ssion Optical Density (TOD) = 0.9
(ii) 60 gloss value = 74%
(iii) Wl.iteness Index = 98 units
Y ~,~,ess Index = -3.0 units
10 (iv) Root mean square roughness (Rq) = 80 nm
Mean surface slope (~q) = 1.6-
The above ~ ", 'es illustrate the improved prupe,lies of polymeric filmsaccG~ling to the present invention.
