Note: Descriptions are shown in the official language in which they were submitted.
-- 1
The invention relates to a catalytically active powder, its
prepara~ion, and a ~ekhod using khe said powder ~o ma~e insula~ing
substrates ac~ivating ~or receiving electrolessly depas~ed
metal in a coherent ~etal layer.
Catalytically active powders directly suitable for activating
electroless ~etallizing have not been ~nown previously.
In deposition of metal on insulating substrates such as for
instance plastics, the following steps may be employed: evaporation
of metal under Yacuum~ application of conductive paints followed
by electrGlytic metal deposition, and elec~roless metalli~ing,
the latt,er in addition possibly being followed by electrolytic
me~al 1 izi ng .
Electroless metallizing has gained widespread use within
electrotech~ics as well as for metallizing finished plastics.
A disadvantage of the kno~ ~ethods for elec~roless metalli~ing
is th_ series of wet process steps used within the commercial
utilization in order to achieve a sufficient adhesion of
the metal layer to the surface of the substrate. The process
steps are ~requently carried out in the following sequence:
etching, r,eutralizing, sensitization9 activation~ acceleration,
and electroless metal deposition. In a great number of processes,
sensitization and activat,on consti~ute one process step,
since the purpose thereof is to situate the ca~alyzing see~s
on the surface of the substrate~ the said seeds catalyzing
, , ~ .
, ,~",~
2 -
the metal deposition from the bath in a metallizing bath.
Such a catalyst sensitizes and activates an insulating surface
for electroless metallizing in one step and consists for
instance of a mixture of SnC12 and PdC12, the so-called palladium-
tin system. This system usually includes an aqueous solutionof a colloidal nature, since it is important to s~abil ke
the system, as precipitation reactions otherwise occur involving
aging and destruction of the catalyzing effect.
The patent literature refers to both organic and aqueous
solutions9 which by influencing an insulating substrate may
make the substrate receptive to electroless metal deposition.
Danish printed accepted specification No. 1329801 describes
how a compound of an element from group 8 or lB of the periodic
system or mixtures thereof in an organic solvent, which in
addition may contain an adhesive, may wet a substrate and
make it catalytically active. 6erman Offenlegungsschrift
~lo. 26 36 457 also s~ates an aqueous ca~aly~ic laquer for
the production of printed circuits and comprislng a binder,
a metal compound, a complex builder, ~nd 3 reducing agent.
Upon application and drying, the said ~etal compound is present
as metal seeds which may be additionally reinforced through
electroless m~tallizing. Aqueous solutions have previously
been encumbered with the draw-back that hydrophobic plastics
substrates can only be wetted with difficulty. This feature
was especially recognized by the so-called ~wo-step process
with separate sensi~i2ation and acti~a~ion steps, cf~ e.g.
., ~ ,
US patent No. 4,042,730, or more de-tailed Metallic Coating
of Plas~tics by William Golde, Vol. I, especially Chapter V.
Danish paten-t applicatlons Nos. 1507/79, 4277/80, and
3300/81, published respec-tively October 11, 19~0, April 10,
1982 and January 24, 19~3; s-tate a method and powders for a
dry sensitization of the surface of an insu:l.atiny substrate
possessing several advantages compared with khe state of the
art, inter alia concerning the distribution of the adhesion
of the me-tal and concerning reduced expenses for the metal
deposition. It should in this connection be stated that
sensitization means one process step applying a chemical
compound to the surface of a substrate. This chemical
compound adheres an activator/catalyst to the substrate
through a galvanic process by contact with an aqueous solu-
. tion containing the said activator/catalyst.
Another manner of making substrates catalytic for
electroless metal deposition includes adhering solid par-
ticles to the surface of the substrate, the solid particles
being catalytical towards electroless metal deposition.
Most suitable are the systems including particles of a
colloidal nature, and systems are known including precious
metals, as well as other systems having an effect with non-
precious metals. The aqueous SnC12/PdC12 catalyst is the
most frequently used, since reasonable stability of the
aqueous solu-tion is obtainable. ~S patent No. 3,011,920
describes a process for preparing such a colloidal catalyst,
which before use is accelerated by the addition of acid or
base. Solid catalyst mixtures - used for the preparation of
an optically transparent liquid - have been
.2 ~ 3
- 4 -
described in US patent No. 3~67~,923~ Such systems are genera11y
encumber.d with the problem of a lacking lony-term stability7
and the literature within the field describas aging effects
and the importance of the use of an acce1erator solu~ion.
Within electroless metallizing, an accelerator sol~tion means
a solution of chemica1s with an acid or alkaline reaction,
the influence of which on the activated substrate pro~otes
the initiation of an electroless metal deposition . In the
present connection, the catalyst solution may in addition
have an activating effect on the ca~alytic powder ~elted
down, which corresponds to the fact that the catalyst solution
in the hither~o known commercial utilization is activated
before use through addition of a chemical. There is still
doubt about!the actual functioning of ~hese systems, and
a discussion ~hereof appears inter alia from "An Electron
Diffraction Study on Mixed PdC12/SnCl2 Catalysts for Electroless
Plating" by T. Osaka e~ al. in Jour. Electrochem. Soc., Nov.
1980, pp. 2443ff, and "A Study on Activation and Acceleration
by Mixed PdC12/SnC12 Catalysts for Electroless Metal Deposition"
2~ by R. Zeblenski in the same journalj December 198~, pp. 2652ff.
It has long been desired to obtain an improved stability
of the PdC12/SnCl2 catalysts which have gained a widespread
use for processes within electrotechnics, cf. inter alia
US patents PJos~ 4,18J,198 and 4,21~,7h8. Regarding the effect
of these catalysts it is considered probable that the precious
metal (e. g. Pd) in the elemental form is s~abilized by tin
; compounds in the solution.
-- 5 --
As described in US patent No. 3,993,799 it has turned ou~
that systems including colloidal par~icles of non-precious
metals are also cakalytic for electroless metal deposit;on
when appropriate baths are employed. It has in connec~ion
with such systems been diflicult to obtain high ca~alytic
activity simultaneously with good stabillty. US patent No.
3,958,048 describes how the colloidal nature eould disappear
in less than 24 hours. US patent No. 4,167,596 describes
the use oP hydro-oxides understoo~ as a mixture of oxides
and hydroxides of cobalt, nic~el, iron, copper, and mixtures
thereof while adding stabili~ers, surfac~ants~ and reactivity-
modifying compounds. After immersion of the substrate into
s~ch a colloidal system, following rinsing a furkher im~ersion
is carried out in a solution with a reducing compound~ Apart
from the wetting of the substrate, such a process has ~he
drawback that it cannot be carried out-selectively. It has
been described in the patent literature how improved adhesion
can be obtained, cf~ inter alia US patent NoO 4,233,344,
wherein hydrazine hydrate is used as an adhesion-improviny
agent. A change of the pH in the colloidal systemg cf. US
patent No. 4,220,678, changes the charge of the colloidal
particles, which has an lnfluence on the adhesion of the
said particles to the substrate.
It has thus been highly desired to improve the adhesion between
~5 colloidal, catalyzing systems and an insulating substrate
and, i~ desired, to position the compounds catalytic for
2~i$~
electroless me-tallizing in a prescribed pattern. In addi~
tion it is of great commercial and practical importance to
produce durable chemicals for use in electroless metallizing.
The present invention provides a powder con-taining
fine-grained par-ticles of a meltable plastics material, one
or more chemical compounds catalytic for electroless metal-
liziny, in an arnount of 0.2-20% by weiyht and a surfactant
in an amoun-t of 0.1 to 100 mille by weight, both being cal-
cula-ted on the plastics material. Upon melting down onto a
substrate and acceleration followed by electroless metalliz-
ing the powder resul-ts in a metal layer adhering to the plastics
powder melted down and having a limit defined by the distri-
bution of the plastics powder melted down.
Catalytically active compounds which have proved
particularly suitable as ingredients of a powder active for
electroless metallizing are compounds of the metals from
group 8 of the periodic system, such as iron, cobalt, nickel,
ruthenium, rhodium, palladium and iridium. In conjuction
with the cataly-tically active compound may be present a tin
compound in which the tin is in the 2-~ oxidation state.
Hydroxides of iron, cobalt, nickel, copper and
silver are capable of activatiny for electroless metallizing
when unstable metallizing baths may be used.
~, ~-
~2~ q~
A commercial catalyst of the PdC12/SnC12 type may be used
as an ingredient in a powder according to khe invPn~ion.
The active chemical compounds for electroless metallizing
may be dispersed as colloidal particles in the plastics
5 material, being a styrene/acryl-copolymer resin.
A mixture of glycerolmonostearate and glyceroldisteara-te
(3% by weight of the plastics) constitutes a surfactant which
as an ingredient in the powder melted down ensures a good
contact wi~h the metallizing bath, whereby a coherent me~al
layer is obtained.
A Fine-grained magnetic material may be incorporated into
the powder in such a manner that the powder may be transferred
magnetcstatically or charged electrostatically in a controlled
manner by means of a magnetic brush arrangement.
1~ Preparation of the powder is preferably carried out by mixing
the plastics material in finely divided form or prepared
through emulsion polymerisation in aqueous medium with an
aqueous solution or dispersi~n of 0.1 - lOO~o by weight
of sur~actant9 calculated on the amount of plastic material,
whereafter the ca~alyzing compound or compounds are added
in an amount of 0.2 - lQ% by w~ight, calculated on the amount
of plastics material, and drying the completed mixture upon
adjustment of the des~red acidity. This method ensures d
-- 8 --
homogeneous distribution of the catalytically active compoundls)
on each ~owder particle.
The plastics suspension may be spray driedp whereby a powder
having a uniform particle size is obtained.
Prior to the drying of the plastics suspension, a reducing
compound or compounds may be added9 the reaction o~ the reducing
compound(s) with the catalytica11y active compound(s) improving
the deposition of metal.
.
Preferably, the powder melted down onto a substra~e is treated
in a salt-acid or alkaline medium with the purpose o~ improving
the deposition of metal and obtaining an improved adhesion
of the metal to the plastics po~der melted down.
The powder is applied to entire surface of the insulating
substrate or that part of the surfacP which is desired to
be metalli~ed, electroless metalli~ing is carried out ~fter
melting down and acceleration.
The powder may be electrostatically transfered to a substrate.
Alternatively, magne~ic compounds incorporated may ensure
magnetostatic transfer under the influence o~ magnetic poles
provided on the substrate in a~vance.
2~
g
The powder staked according to the invention, where a plastics
powder contains the well-known PdCl2/SnCl2 catalysts or other
precious metal catalysts of colloidal nature or hydro-oxides
of non-previous metals, as well as surfactants, is characteri~.ed
in that after melting down the powder onto a substrate and
suitable acceleration, metallizing with a good adhesion and
a sharp metallizing limit (boundary or edge) ar~ achieYable.
Such a powder provides an essential improvement compared
to the prior art. Thus the durability of the catalyzing
compounds has been considerably increased, not the least
due to the acceleration not being carried out until the powder
has been melted down onto the substrate, and not as by the
conventional wet process where acceleration of ~he catalyst
is carried out prior to immersion of the substrate. It has
not previously been recognized that by using catalysts in
the form of catalyzins plastics powder~ whether the powder
oontains precious metal systems or non-precious meeal compounds,
considerable advantages can be obtained. For instan~e, there
is no need ~or etching of ~he substrate in order to form
?O cavities in which the catalyzing compound may be sucked up
so as to ensure a good adhesion. Furthermore, the colloidal
nature of the cataly~ing compounds of a powder ascording
to the invention has been stabilized in a particular ~anner
by the fine-gra~ned plastics powder usedO
L2~
- 10 -
The cataly~ic compounds in a powder according to the invention
may include any des,red compound of the metals ~om group
8 of the periodic syste~, particularly iron, cobalt7 nickel,
ruthenium, rhodium, palladium, iridium in addition to a tin
5 compound, the tin to as large an extent as possible being
present in the oxidation step 2+, or another reducing compound
of inorganic or organic nature. In addition, the catalytically
ac~ive compound may be from group lB of t'ne periodic system,
iOe. copper, silver, gold.
When the catalyzing compounds are complex compounds, i~ may
be necessary to use an accelerator) which may be acid or
alkaline, for the metallizing process. When commercial catalysts
of ttle PdC12/SnC12 type are used, an aquevus salt acid solution
(conc. HCl to H20 e.g. 1:2) is a suitable accelerator. In
this manner the stabilizing alkaline halides are remo~ed
from the cataly~ing powder melted down, wh~reby a more water
permeable surface is achieved in addition. In the following
metallizirg process, this increased surface porosity causes
an extremely good adhesion of metal to melted down plastics
powder.
For the preparation of a powder according to the invention
including an Sn-Pd catalyst it may under certain circumstances
be undesired that alkaline halides are used to for~ a complex
compound with PdCl2, since this can result in a very fatty
powder. However, US patent No. 4,2129768 states ~hat other
halides are applica~le, e.g. CaC12~6H20 and LaC13. 7H20.
It has been found particularly advantageous for a powder
according to the invention to utllize a double salt of CaC12.
6H20 and PdC12, since a very electros~atic powder is ~hereby
ob~ained. Another manner of avoiding unfortunate properties
by a powder including a conventional Sn-Pd catalyst, such
as e.g. 9F from Shipley Corp.~ is to use a plastics emulsion
instead of a jet-ground powder. In this manner khe concentration
of the dDuble salt is reduced~ ~he dou~le salt con~aining
the catalytically active meta7.
In the fleld of conventional elec'croless metallizin~, surfactants
have usually been added to the baths used. It was not previously
reco~nized that an improved effect was obtainable by means
of a powder capable of activating the surface of a substrate
lS for electroless metallizin~ and including a sur~actank.
The hydro~ho~ic part of this surFactant adheres to the hydrophobic
plastics material, being the most essential ingredient of
the powder, while the hydrophilic properties ensure a good
contact bet~en the powder melted down and an aqueous medium.
Especially regarding commercial catalysts of the PdC12/SnC12
type the great advantage is obtained in conneckion with the
invention in that the said catalyst is not actiYated for
electroless metal deposition until the powder according to
the invention has been melted down, the substrate with the
powder melted down being immersed into an acid or alkaline
medium. As a result, both the powder and a plastics film
formed of said powder demonstrate a durability not preYiously
known.
A method for the preparation of a powder according to the
invention includes the steps of the plastics material in
the fine-grained form or prepared by emulsion polymerisation
in aqueous mediuln being mixed with an aqueous dispersion
of a surfactant, whereafter the ca~alyzing compounds are
added and dried upon adjustment of the desired acidity, e-97
10 spray dried. The method is thus carried out in an a~ueous
medium, and colloidal particles present ther2in or precursors
for such particles, inter alia as a consequence of the influence
of the surfactant, adhere strongly to each plastics particle,
acting as stabilizer as well as a cement during the melting
down of the dry powder, the said cement binding the compounds
activating/catalyzing for the electroless metallizing to
the surface of the substrate. The aqueous medium furthermore
has the advantage that par~ly hydrol~ysed and oxide-containing
compounds are present, which can be ~elted down through for
instance the spray drying process in the sur~ace of ~he powder
particles and thereby improve the wetting of the melted down
powder.
The preparation of a powder according to the invention including
non-precious catalyst compounds may be carried out on the
basis of commercially available solutions with stabilizers
present therein and which ~ay be acceleraked in a suitable
manner, or the colloidal particles may be precipitated prior
to the drying process through the adrJition of reducing surf~c~-
ac~ive and precipitating reagents. In the subsequ~nt drying
5 process, the colloidal nature is in a particular manner stabilized
on the surface of each powder gain as islands of catalytically
active compounds.
A powder according to the invention m~y be applied to an
insulating substrate through sprînkling, electrostatic or
10 magnetostatic transfer directly to the substrate or via a
light-sensitive master, cf~ the prior art. The powder is
then melted d~wn in order to ob~ain a suitable adhesion to
the substrate. If the catalyzing co~pounds are so stable
that they cannot directly initia~e electroless metallizing,
accel~ration can be carried out. Such acceleration may include
the steps of the powder melted down on the substrate being
subjec~ed ~o ~he influence of an acid or alkaline mediuln.
As a result the catalyzing compounds are made active for
electroless metallizing. In addition, a more porous structure
is obtained, which improves additionally the adhesion of
the electrolessly deposited metal. In a la~er galvanic prooess
it is possible to increase the thickness of the metal layer.
6~
- 14 -
With;n the neighbouring field, photocopying, magnetic one-
component toners have gained inoreasing use. For use ln
equipment using this principle, it is possible to prepare
a powder which includes a magnetic material in each powder
S particle, e.g. oxides of iron, the partlcle size of which
is usually less ~han 2.5 ~m. In addi~ion it is possible
to precipitate a thin layer of pallad1um on these grains
of magnetic material, e.g. by reducing a palladium salt dissolved
in a slurry of the said grains on~o their surface, e.g. by
addition of formaldehyde. Whether these grains of magnetic
material have a thin layer of palladium on the surface or
no~. or are commercial powders such as for instance Bayferrox
Gl fr~em~rk~ ~ f
(Bayer Che~ie3, a powder according to the inventinn can be
prepared which in each powder grain includes grains of magnetic
~aterial. I~ is most advantageous ~ha~ these are slurried
in a plastics emulsion, to which one or more of the catalytically
active compounds as well as a sur~actant are added, the surfactant
i~proving the hydrophilic properties of the powder prepared
when the powder is melted down onto an insulating subs~rate.
The invention thus provides a catalytically ac~ive powder
which can be used directly to initiate electroless metallizing~
and which possesses a novel capacity of achie~ing good adhesion
~o the substrate as well as pore~free merging. The stability
of the powder prepared has proved to be surprisingly good,
and i~ is of great environmental importance ~hat transport
of a catalyst for electroless metallizing by using the powder
according -to the invention may be carried ou-t as transpor-t
of a stable powder instead of being transpor-t of liquids
detrimen-tal to environmen-t.
For further explanation of -the powder according -to
the invention, its prepara-tion and use, the following
Examples are given.
Example 1
__ _
A powder including the following ingredients:
Styrene plastics (Piccolastic D 125, a trademark
of Hercules Corp.) 100 g
PdC12 0.1 y
SnC12.2H2O (all Sn-compounds have been converted
into equivalent SnC12.2H2O) 5 g
Surfac-tan-t (Span 60, a trademark of ICI-Atlas) 0.4 g
Example 2
A powder as stated in Example 1 was prepared by
100 g of plastics material (Piccolastic D 125, a trademark)
upon crushing being ground on a Trost jet mill. The finely
ground powder was slurried in an aqueous dispersion contain-
ing the surfactant in an amount corresponding to 4% by
weigh-t of the plastics material. 5 g of SnC12.2H2~ were
weighed ou-t and heated to 95C, whereafter 0.1 g of PdC12
was added. Upon cooling, this mixture was crushed and
dissolved in water, whereafter this solution was added to
the plastics suspension. Upon adjustment of the pH to 8 by
means of ammonia water, the plastics suspension was dried on
a spray drier (supplied under the trademark NIRO Atomizer
model Minor) with a rate of rotation of the atomizer wheel
of 35,000 rev/min. and with a feeding velocity and supply of
hot air adapted in such a manner that the input temperature
and the output temperature were 180C and 80C,
respectively.
- 15 -
~L2~ 2~
_ample _
A powder including the Eollowing ingredients:
Piccotoner 1200 (a trademark of He:~cules Inc.) 100 y
Ca-talyst 9F (Shipley Inc.) 5 g
Atmer 122 (a trademark oE ICI-Atlas) 0.3 g
Example a,
A powder as s-tated in Example 3 was prepared by
100 g of Yiccotoner 1220 (a trademark) upon crushing being
added to an aqueous dispersion containing 0.3 g oE Atmer 122
(a trademark) which is a surfactant, in 1 litre of liquid.
An amount corresponding to 5 g of solid matter of Catalyst
9F, which is a commercial catalyst of the PdC12SnC12 type
produced by Shipley Inc., was diluted to a volume of 1 litre
and pH was adjusted by means of a 6 NaOH solution to about
pH ~. Under heavy stirring the diluted catalyst solution
was added to the plastics suspension. By 6N NaOH pH was
adjusted to 7, and the mixture was dried on a spray drier
(NIRO (a trademark) Atomizer model Minor) with a rate of
rotation of -the atomizer wheel of 35,000 rev/min and a
feeding velocity and supply of hot air adapted in such a
manner that the input temperature and the output tempera-
ture were 180C and 80C, respectively.
6~i 13
Example 5
The use of powder as sta-ted in Example 3 i5 per-
formed by applying it to an insula-ting substrate comple-tely
or partly, -the powder being sprinkled through a serioyra-
phic mask, transferred electropho:rographically or in ano-ther
manner, whereafter it i9 melted down at a temperature of
140C. The subs-trate with the powder melted down is immer-
sed :into a solution of concentrated hydrochloric acid and
water in the ratio 1:3 for a period of 8 minutes. Subse-
quen-tly, i-t is treated in an accelerator solution (supplied
uncler the trademark Shipley l9H) for 3 minu-tes in order upon
rinsing to be metallized in a Shipley 328 (a trademark)
electroless copper bath at room temperature.
Example 6
A powder including the ingredients:
Org-D-21 (a trademark of Hercules Inc.)100 g
AgNO3 7.5 g
Atmer 114 (Surfactant, a trademark of ICI-Atlas) 0.3 g
Example 7
A powder including the ingredients:
Org-D-21 (a trademark of Hercules Inc.)100 g
C C 2 2 8.0 g
Atmer 114 (surfactantr a trademark of ICI-Atlas) 0.3 g
Example 8
A powder as stated in Example 6 was prepared by
100 g of plastic material upon crushing being ground on a
Trost je-t mill. The finely ground powder was slurried in an
a~ueous dispersion containing the surfactant (supplied under
the trademark Atmer 114) in an amount corresponding to 3% by
weight of the plastics material. An aqueous solution of the
metal salt was added in the desired amount, whereaf-ter pH
was adjusted to 8 by 6N NaOH. Subsequently, the plastics
suspension was dried on a spray drier (supplied under the
~,,,C
trademark NI~O Atomizer model Minor) with a rate of rotation
oE the atomizer wheel of 35,000 ~ev/min and a feediny velo-
city and supply of ho-t air adapted in such a manner tha-t~the
input temperature and the output temperature werc 170~C an~
70C, respectively.
_ample 9
Analogous wi-th Example 8, a powder as sta-ted in
Example 7 was prepared.
Example 10
A powder of a plastics material containing hydr-
oxides of a metal present in one or more oxidation steps was
prepared by 100 g of plastic material (supplied under the
trademark Piccotoner 1200) being slurried in a dispersion of
a surfactant (Atmer 122, a trademark of ICI-Atlas), the
amount of which corresponded to 3~ by weight of the plastics
powder. An aqueous solution was admixed which contained 8 g
of CuC12, and during heavy stirring an aqueous solution af 2
g of ICBH4 was addi-tionally added, whereafter a 6N NaOH
solution was added until a pH of about 9 was reached. The
resulting plastics suspension was dried on a spray drier
(supplied under the trademark NIRO Atomizer model Minor)
with a rate of rotation of the atomizer wheel of 35,000
rev/min and a feeding velocity and supply of hot air adapted
in such a manner that the input temperature and the output
temperature were 200C and 80C~ respectively.
.,, ,. . ~
,' :\
Example 11
An aqueous plastics emulsion (Dresinol, a trade-
mark of Hercules Inc.~ corresponding to 100 g oE solid ma-t-
-ter was added to an aqueous dispersion of 0~3 y of sur~ac-
tan-t (Span 60, a trademark of ICI~Atlas). ~uring heavy
stirriny 30 g of Fe3O~ of a particle size of less than 0.5
~rn were added -to the above. Fur-thermore, an aqueous solu-
tion of Ca-talyst 9F (Shipley Inc.) was added in an amount
corresponding to ~ of solid matterl and -the pH was adjusted
to 8 by 6N NaOH, whereaf-ter spray drying was carried out on
a ~IRO (a -trademark) Atomizer model Minor with a rate of
rotation of the atomizer wheel of 35,000 rev/min and a
feeding velocity and supply of hot air adapted in such a
manner that the input tempeature and the output temperature
were 160C and 65C9 respectively.
Example 12
A powder including the following ingredients:
Piccotoner 1200 (a trademark of Hercules Inc.) 100 g
PdC12 0.4 g
2.6H2O 2.8 g
2. H2O 2.8 g
Atmer 121 (a trademark of ICI-Atlas)0.3 g
-- 19 --
. . , ~ .
~ .:
Example 13
A method for -the preparation of a powder as stated
in Example 12 included the following s-teps: 0.~ g oE PdClz
were dissolved in 2.~ g of CaC12.6H~O which were kep-t melted
at 95 C. After 15 minutes 2.8 g of SnC12~2H2O were added.
This solu-tion was now added -to a plastics suspension, where
100 g o~ Piccotoner 1200 ~a trademark) which in advance had
been jet-ground, were slurried into 500 ml of distilled
water, wherein 300 mg of surfactant Atmer 121 (a trademark
of ICI-Atlas) were dispersed. The alkalinity was adjusted
to pH 8 by 6N NaOH, and a NIRO (a trademark) Atomizer model
Minor was used for the spray drying. The atomizer wheel was
adjusted -to 35,000 rev/min, and the feeding velocity and
supply of hot air were adjus-ted in such a manner that the
input temperature and the output temperature were 180C and
80C, respectively.
- 20 -
2 ~ %~
- 21 -
Example 14
A powder as prepared by the mekhod described in Examp1e 11
was transferred in a device for photocopying, whereby po~ders
containing magnetic matter are electrDstatically transferred
to a light~sensitlve master, the masker optionally being
a polyester film coated with a light-sensitive material.
A picture obtained electrostatically by illuminat10n on the
light-sensitive surface charged to a positiYe high voltage
of 2.8 ~V was produced by the said powder by means of a conventiona7
magn2t brush arrangement kep~ at ground potential. Transfer
of ~he result~ng electrostatic picture to an insulating substrat2
was sarried out by charging the substrate.
A powder as prepared by the method described in Example 11
15 was used for developing a magnetically structured CrO2-coated
polyester film, on which a magnetostatic picture was produced
by illumination with a Xenon ~ ash la~p. During ~his procedure,
the ~rO~-coated ~agneti~ed film was illuminated throush a
photographic ~ilm where the light penetrated the bright areas
20 of the ~ilm and heated khe magnetize~tilm to ~ore than its ,'
Curie point. The developing was carried out by a "powder `,
cloud" technique (powder cloud in flow of air). The powder
grains adhering to the magnetized film were subsequently
transferred to an insulating ~ubstrate by the said subs~rate
being brought to a positive potential of about 20 kY.
~2~2
- 22 -
Exam~le 16
Powders as s~ated in Examples 1, 3, 6, 7, and 11 were in
turn transFerred electrostatically as fnllows. The powder
was charged electrostatically to a voltage o~ 2u2 kV in a
conventional device for electrostatic powder transfer. By
means of a ~low of air the powder was transferred to a substrate
whereaft~r it was melted down by heating to the melting temperature.
~e~
A powder with a composition as stated in Example 12 and prepared
as stated in Example 13 was mixed in the weight ratio 2 to
100 with iron powder of a particle size of 50 to 100 ym (a
conventional carrier for use in magne~ brushes). ~y such
a developing mixture in a conventional magnet brush arrangement,
latent electrostatic pictures were developed on a photo-sensitiYe
master, which through conventional corona discharge had
been charged to a negative high voltage of 3.2 kY and subsequently
illumina~ed selectively by means of a patternD Transfer
from the said photo-sensitiYe master was carried out by charging
an insulating substrate so that the partioles werQ transferred
20 by attraction. In a conventional manner the particles were
fixed to the insulating substrate and electroless ~etallizing
was carried out~
