Note: Descriptions are shown in the official language in which they were submitted.
19 r1P~I '98 11:50 1'1ERCK PI~ITENT Gl''l~H 49 6151 727191 5.3~13
FILE, ~tN TH~ r ~
~EXT-TRANSLA~i~N
-- 1 .
~ltiluy~r ~te~~~ronc~ ~ ~n
~ e inven~ion r~latR~ to multilayer inter~erence
pigments consis~ing of a tran~parent c~r~ier material
coat~d with ale~nsti~g l~e~ of me~al ~x~des o~ low a~d
hi~h re~ractive index.
Multilayer inter~ren~e ~ig~ent~ with al~ernating
layer~ o~ materi~l~ o~ high and low refractive i~dex are
~o~. They dif_er in re~pect ~ the carrier material and
o~ ~he material for the individual la~ers, and in the
prepara~icn ~rocess. ~he layers are pre~ed either by
precipitation in a wet pro~e~s or by vapour de~ositicn or
sput~ring under vacuum. The layers a~pli~d ko the
~arrier or to a rel~a~e ~yer are all opticall~ active
~ nd ~ontribute to the development o~ the inte~erence
c~lour~. The carrier m~ri~l~ are o~ica~ly ac~ive only
in excep~ion~ case~.
US 4,43~,010 de~cri~es a mu~tilayer inrer~erence
pigment conAi~ting of a c~ntr~l layer o~ a re lective
material ta~inium) and alternaeing l~ye~s o~ two
transparent, diel~c~ri~c mat~rials o~ high and low refr~c~
ti~e index, ~or exampIe tit~nium dioxide and silicon
dioxide, on bo~h ~ides o~ ~he cen~ral alumini~m layer
~his pigment i~ used ~or ~he printing o~ securiti~.
JP H7-759 (Ko~oku) de~cribe~ a multilayer inter-
~S feren~e pig~ent with a metalllc lu~tre. It con~ist~ ofa ~ubstrate coated with alt~rnating la~er-~ o~ ti~ni~m
dioxide and ~ilic~n dioxide. ~he ~u~trate i~ formed ~rom
alwmin~u~, ~old or ~lver ~lake~ or ~akes of mi~a an~
~la~s coated with metals.
H7-246 366 describe~ a multilaye~ inter~erence
pigment with alternating layer~ of a material o~ high
refractive index and a mate~i~l o~ low ~e~rac~ive i~de~.
The sub~trate used is glas-~ and, ~or the coating, 6ilicon
dioxlde and ~i~anium dioxid~. The indi~idual laye~s
35 po~es~ a~ opti~ kne~ w~i¢~ i~ ~n integ~al m~l-
tiple o~ a quarter o~ the wavelen~th at which inter-
~erence i-~ expected. This res~lts, ~or the titani~m
dioxide layers, in a layer ~hi~kness o~ 44.~ nm at a
CA 02238035 l998-05-l9
19 1'1~I '98 11:50 r1ERCK PRTENT Gl'1BH 49 6151 7Z7191 5.4~13
- a -
re~ractive ;~R~ o~ 2.7 and, for the ilico~ dioxld~.
layer~, in a lay~r thickness o~ 80 nm at a re~racti~e
i~d~x of ~.5.
In the pigments described a~ove, the ~ilicon
dioxide lay~ a~t a~ optically a~ti~e ~yerx ~hi~
optically activR e~ct ~egins with ~ layer thickness o~
~bout 20 nm. Si}icon dioxide layers, however, are al~o
employed as dif~usion h~rrier~ in condu~tive pi~mants.
For instance, EP 0 373 575 de~cribes conductive platelet-
~orm pigment~ co~si~~ing of ~ pla~elet-~or~ me~al o~ide
ar ~ a ~la~el~t ~or~ ma~rial coated with m~tal oxide,
and a conductive layer, the metal axide layer and c~n-
ducti~e la~er bein~ ~a~ted by ~ silicon dioxide layer
which prev~nts ions ~rom the sub~trate or ~rom the metal
oxide layer di~using in~o the conduc~ive l~yer in ~he
cour~e of calcinin~; otherwi~e, the conductivity o~ the
a~timony-~oped ~n oxide layer i~ reduced. T~e t~ickne~s
o~ the silicon d;oxide interlayer i~ between 8 and 30 nm
a~ conccntra~io~ o~ ~rom 5 to.~0% ~y weight o~ sio~
based on the s~bs~ra~e.
It h~s ~urpri ingly been ~ound that the quality
o~ cu~tom~y commerci~l inter~eren~e pigments in re~pect
o~ their mechanical properties can be markedly improved
i~, in the ~tal oxide l~yer~ o~ high re~rac~ive index,
2S at lea~t one in~erlayer o~ another metal oxide i~
.,_,
arranged which posses~e~ no optical activity.
~ ~eatu~e o~ ap~ropriate metal oxide~ is that
de3pite their low thickneY~ the~ are obtained a~ ~ la~er
even a~ter the calc~ning o~ the pi~ment, since they do
not readily ~orm mixed phase~ with the su~ro~ metal
oxide~ of high re~active index Moreover, they ha~e a
markedly lower re~ractive i~ex ~han the metal oxide~
which ~orm thc optical layer
The invention t~ere~ore provides multilayer
35 interference pi~men~cs consist;Lng o$ a carrier material
eoaced w~th alte~natin~ layer~ o~ metal oxide3 o~ high
and low re~ractive inde~, the l~yer(~ o~ the m~t~1 oxide
o~ low re~ractivc index bein~ optically inacti~e
The in~ention additionally provides a proce3s ~or
CA 02238035 l998-05-l9
19 1'1RI '98 11-50 ~IERCK PRTE~IT Gl'1BH ~9 6151 7Z7191 5.5~13
preparing the noYel pi~ent~, ~n whi~ the tran~parent
carrier ma~erial i~ ~u~pended in water and coa~-ed in
alternation with a metal oxide.~ydrate of hi~h re_ractive
i~dex ~nd ~ metal oxi~e hydrate of low refractive indcx
~y addition and hydrolysis of ~h~ coxre~ond~ng ~ater-
col~le metal compounds, the p~ necessary for the ~recip-
itation o~ the respec~ive metal oxide hydrate bein~
e~tablished and kept constant by simultaneou~ addition o~
acid or ~a~e, and then the coated carri~r mAterial i~
separat~l of~ from the aqueous ~iu~pen~ion, dried, an~ i~
deQired, calcined.
The invention p~ovides, furthe~more, ~or the use
- o~ the no~el ~igmen~ ~o~ pigmenti~g pain~, p~inting
inks, pla~tics, ~laz~s ~or ceramics and gla~ , as well a~
cosm~tiC~.
~or this purpo~e they can be employed as mixture~
with cuctomar~ co~mercial pigments, for exam~le i~organic
or or~anic ab~orb.~ion pigment.q, metal-ef~ect pigm~nts and
LCP. pi~m~n
~0 Th~ carrier ma~erial i~ mi~a, anot~r phyllo~
i~te, gl~s~ flakes, or platelet-~orm ~ilicon dioxide,
which i~ prepare~ by the techni~ue described in WO
9~/~8237 on a continuou.~ belt by ~olidifi~ion and
hydroly~s o~ a waterglass solution.
Z5 The metal oxide o~ ~i~h refra~tive ~ndex ~an ~e
an oxide or mixtures of oxides with or witho~ ~rbing
~roper~ie~. su~h a~ Tio2, ZrO~, Fe~O3, Fe3O~, Cr2O3 or ZnO,
or a compound o~ hi~h re~ractive index ~uch as, ~or
example, iron ti~anate~, iron oxide hydrat~s an~ tit~nium
suboxide~, ~ mixture5 ~ndtor mixed phase~ of these
compound~ with one ano~her or with other metal o~ide~
~ he ~1 oxid~ ~ lo~ re~ra~ti~e index is sioi,
Al~03, AlOO~, ~03 or ~ mixture ther~o~ and ~an likewi~
h~ve absoxbing or non--ab~orbing properties. I~ desixed;
the oxide layer of low -re~r~c~ive index may include
alkali metal oxides and alkaline ear~h metal oxides as
c~n~ t i tuent s .
T~e metal oxide layers are pr~rably applied by
a wet-ch~mical method, i~ whi~h oontext it i~ p~sible t~
CA 02238035 1998-05-19
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e~ploy.~he wet-chemical coating techni~ues de~elo~ed ~or
the pr~paration o~ pearl lustre pi~ments; techni~ue~ o~
~hi~ kind are descri~ed, ~or example, in DE 14 67 468,
~E 19 5~ q8~, DE 20 ~9 56~, DE 2~ 14 ~45, DE 2~ 15 191,
DE ~2 44 2g8, DE 23 13 331, ~E 25 2Z 572, ~E ~1 37 808,
D~ 31 37 80~, ~E 31 5~ ~43, ~E 31 51 ~54, DE ~1 51 ~55,
DE 32 11 602, DE 32 35 017, or el~ in ~urther patent
documents and ot~er publications.
For ~oa~ing, ~he ~b~tra~e particle~ are ~U3-
~n~ed in water, and one or more hyd~olysa~le metal ~alt6
are A~e~ at a p~ which i~ appropriate ~or hydrolysis and
i~ chosen such that the metal ~Yi ~oe an~Jox me~l o~ide
hydrates ar~ precipitated directly onto the particle~
without any in~tance~ o~ cecondary precipitatio~. The p~
15 i8 kep~ con~a~t us~lly by simul~aneou~ meter~d addition
of a ~a~e or alknli. The pigments are su~se~uent~
~eparated of ~, wa~hed and dried ~nd, if deaired, eal-
' cined, the c~lcination temperature posaibly beinyoptimized in re~pect o~ the particular coating. I~
~e~ired, ~ollowi~g the application o~ individ~al cQating~
the ~igment~ ean.~e separated o__, dried and, i~ desired,
calci~ed ~e~o~e being ~e~uspended ~or the applic~tion oi
~urther lay~rs by precipitati~.
Pre~erably, u-~e is made o~ titanium dioxide as
2~ the metal oxide o~ high re~rac~ve index and o~ silicon
dioxide a~ the metal oxide o~ low re~ra~tiv~ index
~o~ th~ application o~ the titaniu~ dioxide
layers, pre~erence is given ~o the ~echnique descrihed i~
US ~,~53,001
An ayueous tit~ni~m ~ olution i~ slowly
to a ~uspension, heated to a~out 50 100~C, in pa~tic-
ular 70 - ~0~, o~ the mate~ial to be coated, and a
s~bst,3ntially ~onstant p~ o~ about 0.5 ~ 5; in ~articu~ar
a~out 1 5 - ~.5, ls maintained ~y ~im~ltan~ou~ metered
addition of a base, for example ~queo~ ,~m~onia soluti~n
o~ aque~us alkali m~tal hydroxide ~olution. As ~oo~ a~
the d~ired ~ayer thi~knes~ of the TiO~ precipitation ha~
en ~eac~d, the addition o~ ~he titanium .~alt ~olution
~nd of the ~a9e i~ 3topped
CA 02238035 l998-05-l9
19 M~I '98 11:51 MERCK PRTENT Gl'113H 49 6151 7Z7191 5.7~13
.
-- 5
~ his p~oce~s, also termed the ti~ratio~ ~o~e~,
iB notable for the ~a~t that it avoi~ an excess o~
titanium ~alt. This i8 achieved ~y supplying ~o t~e
hy~rolysis only that qU~ntity per unit time which is
necessary for uni~orm coatin~ with the hydrat~d TiO~ a~d
which can bo re~eived per unit time by the available
~urface area o~ the particle~ to b~ coated. ~her~ iY
there~or~ no ~roduc~on of hydrated tit~nium ~ioxide
~ar~-icles no~ precipi~ated on ~he sur~ace ~o be coated.
10For the applica~ion o~ the Qilicon dioxide
layers, ~he ~o~lowing ~roce~ o ~e e~ployed; a.sod~'u~
silicate ~olution is metered into a suspension, ~eated to
~~ about ~0 - 1004C, in particu~ar 7Q - 80aC, o~ the
material to be ~oated. The pH is held con~tant at 1.5 to
10, pre~erabl~ at ~ ~ to 8 ~, ~y ~imultaneou~ addition o~
10% hydrochloric acid. Stirring i~ ca~ri~d out for
~urther 3~ ~in~te~ ~ollowin~ addition o~ the silicate
~olution.
~t i~ al80 pos~ible to alter the powder colour o~
the pi~ment by applying ~urther layer~, ~or example
eolo~red metal oxide~ or PrusYian Blue, tr~nsition ~l
com~ound~, ~uch a~ compounds o~ Fe, Cu, Ni, Co or Cr, ~or
examp~e, or organic oompo~nd~ ~u~h as d~e~ or colour
lakes.
25It i~ ~dditionally possible to subiect the
~i~ished ~igme~ ~o an a~tercoating or aftertreatment
process which further incr~a~ea ~he 3~abil~ty to ~ig~t,
weathe~ ~nd ~he~i~ , or whi~h facilitate~ the handling
of the pi~ment, especially i~6 incoxporatio~ in~o di~~er-
30 ~nt media . 9u~ table a~tercoatin~ and a~tertr~e~
proce~e~ are tho-~e de~cri~ed, ~ e~m~le, in D~-C
22 1~ 191, ~-~ 31 ~1 354, ~3~A 32 35 017 or
DE-A 33 34 5~8
~he substance~ additionally ~lie~ ~ake up only
35about O 1 to 5~ by wei~ht, pre~erably abo~t 0.5 to 3~ by
wei~ht, of ~he ove~all pig~ent
Pre~erence is al~o ~ive~.~o an additional co~ing
with complex salt pigment~, e~ecially ~yanofe~rate
complexc~, for ex~mple Pru~sian ~lue and Turnbull.~s Blue,
CA 02238035 l998-05-l9
19 r1RI '98 ll:5Z ~1ERCK PRTENT G11BH 49 6151 727191 5.8~13
a~ i~ descri~ed i~ E~ ~ ~412 173 ~sic] and DE 23 13 332.
The ~ovel pi~ment can ~180 be ~oated w~h organac
dyes ~nd, in particular, wit~ phthalocyanine or metal
phthalo~yanine ~nd~or i.~danthr~ne dye~ in accordance with
DE 4009 567 ~hi~ is done by preparin~ a su-~pen~ion o~
t~e pigm~nt in a ~olution of the d~e and then h~ingin~
thi~ ~u~pensi~n together wieh a solvent in which the ~y~
~s o~ low or zero ~olubility.
The thicXness of the interlaye~ o~ metal- oxides
l~ o~ lo~ xefra~iv~ i~dex wi~hin ~ ~et~l oxide layer ~
hi~h refractive index is from l to 20 nm, pre~erably ~rom
to lO nm. Within this ran~e, a me~al oxide laye~ of low
re~ractive index, fcr example 3i~icon dioxide, i~
optically inactive, which is an essential ~eat~re o~ the
.15 present invention.
The thi~kn~s o~ the layers o~ me~l oxide~ of
high refra~tive index i~ b~tween 20 and 350 nm, pre~er-
a~ly ~etween 40 and 260 nm. since the interlayer~ o~ low-
refractive-i~dex metal oxide~ gre~ly i~e~e ~
mechanical 3ta~ility of th~ layer~ of high-re~ractive-.
index ~tal o~ides, it is al~o possible to prepare
thic~er laye~s o~ adeguate stability. In p~actice~ .
however, layer thicknes~es o~ only up to 260 nm ~re:
e~ployed, w~i~ in ~he c~se o~ a titaniuffl diox~de-mic~
pi~ment correspond~ to IIIrd-order ~reen.
_~ .
The n~mber and position o~ the interlayers i~
depende~ on ~he ~ot~1 l~yer thi~kne~ of the met21 oxide
layer o~ high re~ractive index The interlayer is pre~r-
~bly arranged ~ch ~hat ~he laye~ thickne~s of the m~tal
oxide layer~ o~ hi~h re~ractive index ~orresponds ~o the
o~tic~1 thic~ess, ~r ~o ~n integral mul~i~le ~ this
optical thickne~s, which is necessary ~or the respective
inte~e~e~ce c~lour. ~or ~xample, ~or a IIIrd-order gr~en
the interlayers would ~e axra~g~d ~uch ~t one laye~ i~
located at Ist-order gre~n and a ~econd layer at IIn~-
order green Thi~ i~ ~lid ~or pure interference colours
In ~ di~erent c~3e, the ~killed worker can de~ermine the
op~imum posiL~ on o~ th~ interlayers without any in~entive
exertion. For exam~le, a more yellow III~d-~r~er g~een i~
. .
CA 02238035 l998-05-l9
19 MP~I ~98 11:52 IrlERCK PRTENT G1~1~3H 49 6151 7Z~191 5.9~13
o~ained i~ the interlayer is placed toward~ I~nd-order
~old, compared wi~h ~ pure III~d-order ~reen in which the
interlayer is arranged o~ ~ IInd-order ~reen.
~x~le
100 g of ~ot~ium mica (10-60 ~1 are ~u~pended
in 2 1 of deioni~ed water. The ~uspen~ion i~ heated ta
75~C, a~ju~t~d t~ a p~ o~ 1.8 with dilute hydrochlo~ic
acid, ~ir~t o~ all coat~d with SnO, by.~i~g 3.3 ml~min
of SnCl4 ~olu~ion (~om ~.~ g o~ SnCl4 and 0.75 g o~ con~
1~ hydrochloric acid in 100 ml of deionized wate~). The p~
s held constant using 32 ~ ~odium hydroxide solution
Stirring i~ contin~ed for 15 ~inute-~ ~nd.~hen
coating with ~iO2 is carried out under the same
pH~temperat~e ~on~ition~ ~y adding 1.5 ml~min o~ Tl~lc
~olu~i~n ~400 g of TiCl4~1) and holding the pH c~nstant
with 32 ~ sodium hyaroxide solution. Coating i~ inte-
rr~pted a~ter the IInd-order green end point ic re~he~
stirring i~ ~ontinued ~or 15 mln~es, the ~H i~ ~j~ted
to ~.O with dilute ~o~i~m hydroxide solution (ov~r ~e.
course o~ about 15 minute~), and then stirring is con-
tinued ~or 10 ~i~utes ~ore
Coatin~ with Sioa is the~ carri~d ouS by ~ddi~g
3 ml/~in o~ ~odiu~ ~ilicate sol~tion (~rom 7.3 ~ o~
~odium ~ilicate wi~h 27 ~ SiO~ ~nd ~0 ml o~ deionized
water~ without pH compensation. Afte~ward-~, ~tirrihg ~
~ontinued' ~or 1~ minute~, the pH is read~usted to 1.8
with di~ute hydroch~oric acid ~ver the cour~e of ahout
10 minutes), an~ a ~econd Tio2 l~yer is applied a~
described above by ~dding TiClC solutlon. Coating is
interrupted af ter the IIIrd-order green com~ari~on en~
point has ~een reached, s~irring i~ ~ontinued ~or
1~ min~te~, ~nd then ~e pigment i~ ~iltexe~ o~ wi~h
suctio~, washed, dried and calcined at 850~C ~ox
30 minute~.
The pigment obtained has an intense green i~ter~
ference calour The division o~ the Tio~ layers is
~ollow~:
CA 02238035 l998-05-l9
19 r1RI '98 11: 53 ~1ERCK PRTENT G~113H 49 6151 7Z7191 5.10il3
,
18t laysr; ~bou~ 17 0 n~
Znd laye~ a~out 85 nm
~otal layer: abo~ 260 n~
~ he thickn~s o~ the SiOa i~terlayer i~ a~ou~
5 nm.
Com~ari 8 on Example
100 g o~ p~ta~$um miCa ~10-~0 ~m) ~xe ~u~pended
in ~ 1 of ~eionized water. The suspension i~ heated to
75~~, ~dju~ted to a ~.H a~ 1.8 with dilu~e.hydroc~loric
acid, ~irst of all coated with SnO~ by ~; n~ 3 . 3 ml~in
o~ SnCl~ solution (from 2.2 g o~ SnCl4 and O . 75 g of conc.
hydx~ochlo~iç a~id i~ 100 ~nl of d~i~nized w~e~) . ~.
is held c~n$tant using 32 % 80dium hydroxide 801ution.
Stirrin~ i~ con~inued ~or lS ~i~utes and then
1~ coatin~ .with TiQ i~ carried out under the 3ame
p~temperature condi~i~n~ by ~dding 1. 5 ml~min ~ Ti~1~
~olu~i~ t400 g o~ TiCl~l) and holdin~ thR pH c~n~t~nt
with 32 ~ sodium hydroxide solution. ~oating i~ inter-
rupted a~ter the II~r~-order ~reen en~ point ha~ been
rea~hed, ~irrin~ is continued ~or 15 minute~, and the~
the p~gmen~ ~s ~iltered o~ with ~uction, wa~hed, dried
and calcined a~ 850UC ~or 30 mi~ute~. Thè thicknes~ of
the Tio~ layer i~ a~out 2~5 nm. The pigme~t obtained~i~
~uch ~ak~r i~ the st~ength o~ the inter~eren;ce c~lour
than the pi~m~nt prep~red in a~corda~ce wi~h the i~ven-
tion. The platelets ~how severe cracks and i~tance~ of
~lakin~ in the Tio~ layer.
.
~olour ~haracteris~ics o~ the re~ul~ing p~gment~ ~Hunter
- L, a, ~) on the ~asis o~ nitro.~el}ulose coat~ng card~
NC coating c~d~ a~e p~pared by care~ully
di~e~ing O.9 g o~ pigment in 5~.5 g ~ N~ ~arnish,
devolatilizing the ~ix~re. and then applying ït with th.e
aid o~ a doctor ~lade t~ a card having a h~l~bl~k and
hal~-white sub~trate. The wet ~ hickne~s i~ 500 ~m
A~ter drying, the colour data are mea~ured u~der ~he
CA 02238035 1998-05-19
19 1'1RI '98 11: 53 ~lEl~!CK PRTENT G~1BH 49 6151 7Z7191 5.11~13
g
~tated geometries.
~omor,ry
450~ 2.5~22.5~ 45~~0
Bl~bcJc ~zd ~ c~ c~L ~l~r!~ e!~¢l
L 3 b L ~ 3 r- ~ b
Exan~le 2a.6 -li 4 -4.0 63 5 -28.3 +5.7 el3.0 +11.5. --0 8
CO~p~r~GOn ~;xa~lc~ '3e.. 4. -5.3 -3.7 5~.9 -:~1.3 +5.g a5.4 ~7.9 ~:0.8
The ~d~nt~ge~ ~ the pigmen~ o~ing ~ the
invention relative to the compari~on example are very
e~idenO:
Colour stren~th, repre ented by t~e ne~ative a value
glos~
~22.5~J22.5~):
28.3 a~ again~t ~1 3
Ll~;n~nce, repre~ente~ by the C val~e glcss
(22 5O~22.5O~;
63.5 as against 5~.
Glo~s, repre~e~ted ~y the ~gloss ~u~b~r~'
L~-~, 5D~Z, 5 _~45 ~O
55.Q as against ~.2
CA 02238035 1998-0~-l9
