Note: Descriptions are shown in the official language in which they were submitted.
SPECI Fl CATI ON
CARBOXYLIC ACID-CONTAINING NICKEL POVVDER AND CARBOXYLIC ACI D-
CONTAI NI NG NI CKEL POWDER PRODUCT! ON METHOD
TECHNICAL FIELD
[ 0001]
The present i nventi on r el at es to a carboxyl i c aci d-
contai ni ng ni ckel powder and a met hod for produci ng the carboxyl i c
aci d-contai ni ng ni ckel powder.
BACKGROUND ART
[ 0002]
A conduct i ve metal powder has conventi onal I y been used
as a conductive mat er i al for an el ectroni c component.
I n a
multi I ayer ceramic capacitor, si nce both a cerami c I ayer and an
i nternal el ect rode I ayer are rapi dl y bei ng made t hi nner,
it is
requi red to form the i nternal electrode I ayer havi ng a t hi n and
uni form t hi ckness.
For t hi s reason, the conductive metal powder
for i nternal
electrodes of the multi layer cerami c capacitor is
requi red to have a narrow parti cl e size di stri buti on.
Further, the
conductive metal powder i s requi red to be free of coarse parti cl es
that could contact both of the adj acent i nternal el ectrodes across
the di el ectri c I ayer, because such coarse parti Cl es cause a short-
ci rcui t of the el ectrodes.
Furthermore, when the conductive metal
powder i s mixed with an organi c sol vent and the I i ke to form a
paste, the conductive met al powder
i s requi red to di sper se
uniformly in the paste.
[ 0003]
The classification of a powder produced by van i ous
product i on methods has been used as a method for produci ng a powder
with a desi red parti cl e si ze di stri but i on. Examples thereof i ncl ude
a method of cl assi fyi ng a powder accordi ng to the difference i n
parti cl e size by usi ng the difference i n sedi ment at i on vel oci ty of
the parti cl e in the gas or liquid phase.
The cl assi f i cat i on i n the
gas
phase is call ed dry cl assi f i cat i on, whi I e that i n the I i
quid
phase i s cal I ed wet cl assi f i cat i on. Wet cl assi f i cat i on has
super i or
cl assi f i cat i on accuracy, but requi r es the use of a I i qui d as a
di spersi on medi um and dryi ng and crushi ng after cl assi f i cat i on. For
these reasons, dry cl assi f i cati on i s by far I ess costly.
1
CA 03174962 2022- 10-6
[ 0004]
However, dry classification had a probl em that it was
difficult to operate for I ong per i ods of time because the powder
adhered to van i ous parts i nsi de the cl assi f i er, cl oggi ng the powder
supply port and the i nsi de of the pi pi ng, etc.
I n addi ti on, the I ow
cl assi f i cat i on accuracy resul ted i n I ow yields.
[ 0005]
As a met hod ai med at sol vi ng such probl ems, Pat ent
Document 1 di scl oses a method of dry cl assi f i cat i on of a powder by
mi xi ng the powder and an auxi I i ary agent consi sti ng of al cohol s
with a boil i ng poi nt of lower than 200 C or lower, such as ethanol ,
and dry classifying whi I e vapor i zi ng the auxi I i ary agent.
[ 0006] Pat ent Document 2 di scl oses a met hod
of dry
cl assi f i cat i on of a powder by mi xi ng the powder and an auxi I i ary
agent consisting of an aqueous al cohol sol uti on containing 10 to 50
vol % of al cohol such as ethanol , and dry cl assi fyi ng the powder
whi I e vaporizing the auxiliary agent.
[ 0007] Pat ent Document 3 di scl oses a met hod
of dry
cl assi f i cat i on of a powder by mi xi ng the powder composed of ni ckel
and an auxi I i ary agent composed of an organi c sol vent havi ng a
f I ash poi nt of 80 C or hi gher, such as di ethyl ene gl ycol , and dry
cl assi f yi ng the powder whi I e vapor i zi ng the auxiliary agent.
There
i s another disclosed method of dry classification of a powder by
mi xi ng the powder consi st i ng of ni ckel and an auxiliary agent
consi st i ng of water, and dry cl assi f yi ng the power whi I e vapori zi ng
the auxi I i ary agent.
[ 0008] Pat ent Document 4 di scl oses a met hod
of dry
cl assi f i cat i on of a powder by mi xi ng the powder and di ethyl ene
gl ycol monomethyl ether, which is a Ii qui d auxi I i ary agent and then
dry classifying the powder.
RELATED ART DOCUMENT
PATENT DOCUMENT
[ 0009] Pat ent Document 1 i s WO 2010/ 047175 Al
Patent Document 2 i s WO 2010/ 057206 Al
2
CA 03174962 2022- 10-6
Patent Document 3 is WO 2010/106716 Al
Patent Document 4 is WO 2012/124453 Al
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[ 0010]
However, the inventors of the present invention have
found a probl em that dry cl assi f i cat i on by adsorbi ng an auxi I i ary
agent such as ethanol onto the powder al I ows the cl assi f i er to be
operated for a I ong per i od of time, but the obtai ned powder
contai ns many coarse parti cl es, so that it is requi red to repeat
classification many times to reduce the number of coarse particles.
Another probl em was that, al though repeated cl assi f i cation may
reduce the number of coarse parti cl es, it is ti me- consumi ng and
costly, resul ti ng i n reduced
productivity and a si gni f i cant
decrease i n the yi el d of the obtai ned powder.
[ 0011]
in addi t i on, the powder obtai ned as descri bed above has
been di f f i cul t to uniformly di sperse i n the paste obtai ned by
mi xi ng wit h t he or gani c sol vent and t he I i ke.
[ 0012]
Accordi ngl y, it is an obj ect of the present i nventi on to
provide a carboxyl i c aci d- contai ni ng nickel
powder havi ng high
di spersi bi I i ty i n a gas phase and hi gh di spersi bi I i ty i n a paste
when used for f ormi ng the paste by mi xi ng with the organi c sol vent
and the I i ke; and a method for produci ng the carboxyl i c aci d-
contai ni ng ni ckel powder.
MEANS OF SOLVING THE PROBLEMS
[ 0013]
Such an object is achieved by the present invention
descri bed in the following items (1) to (9).
(1) A carboxyl i c aci d- contai ni ng ni ckel powder which contains
a pl ural i ty of ni ckel parti cl es and has a carboxyl i c acid on a
surf ace of each of the ni ckel parti cl es,
wherei n by using a TG-MS, when a temperature i s rai sed from
38 C to 600 C at a heat i ng rate of 20 C/mi n i n an i nert atmosphere,
a peak is detected i n a mass chromatogram of a mol ecul ar i on of the
carboxyl i c acid, and wherei n when a boil i ng
poi nt of the
3
CA 03174962 2022- 10-6
carboxyl i c acid is Tbp [ C], a peak top of the peak exi sts within a
range of (Tbp + 100)QC or hi gher and 600QC or I ower, and
wherei n a content of the carboxyl i c aci d per 1 m2 of a surf ace
area of the ni ckel
part i cl e consti tut i ng the carboxyl i c aci d-
contai ni ng ni ckel powder i s 155 lig or more and 450 1..tg or I ess.
[ 0014] (2) The carboxyl i c acid-containing ni
ckel powder
accordi ng to the above i tem (1), wherein by using the TG-MS, when
the temperature i s rai sed from 38QC to 600QC at the heating rate of
20QC/mi n in the i nert atmosphere, there i s no peak top of the peak
i n the mass chromatogram of the mol ecul ar i on of the carboxyl i c
acid wi t hi n a range of (Tbp - 50) C or hi gher and (Tbp + 50) C or
I ower.
[ 0015] (3) The carboxyl i c acid-containing ni
ckel powder
accordi ng to the above i tern (1) or (2), wherein the carboxyl i c acid
has the boi I i ng poi nt of 100 C or hi gher and 270 C or I ower.
[ 0016] (4) The carboxyl i c aci d- contai fling
ni ckel powder
accordi ng to any one of the above items (1) to (3), wherein the
carboxyl i c aci d has a mol ecul ar wei ght of 40 or more and 160 or
I ess.
[ 0017] (5) The carboxyl i c acid-containing ni
ckel powder
accordi ng to any one of the above items (1) to (4), vvherei n the
carboxyl i c aci d has 2 carbon atoms or more and 9 carbon atoms or
I ess.
[ 0018] (6) The carboxyl i c acid-containing ni
ckel powder
accordi ng to any one of the above items (3) to (5), wherein the
carboxyl i c acid is at I east one sel ected from the group consisting
of aceti c aci d and propi oni c aci d.
[ 0019]
(7) A method for producing a carboxyl i c aci d- contai fling
ni ckel powder def i ned by any one of the above items (1) to (6), the
method compri si ng,
bri ngi ng a carboxyl i c aci d in a gaseous state i nto contact
with a ni ckel powder di spersed i n a gas phase.
4
CA 03174962 2022- 10-6
[ 0020]
( 8) The met hod for producing the carboxyl i c acid-
containing ni ckel powder according to the above item (7), wherein
the
ni ckel powder i s di spersed i n an atmosphere cont ai ni ng the
carboxyl i c aci dint he gaseous state.
[ 0021]
( 9) The met hod for producing the carboxyl i c acid-
containing ni ckel powder according to the above item ( 7) , wherein
under the condi ti on that the ni ckel powder bei ng i n a dispersed
state in a gas phase at the ti me of generati on has been dispersed
i n the gas phase, the carboxyl i c aci d in the gaseous state i s
supplied i nto the gas phase.
EFFECTS OF THE INVENTION
[ 0022]
Accordi ng to the present i nventi on, it is possi bl e to
provide the carboxyl i c aci d- cont ai fling ni ckel powder havi ng the
high di spersi bi I i ty i n the gas
phase and havi ng the high
di spersi bi I i ty i n the paste when used for f ormi ng the paste by
mi xi ng with the or gani c sol vent and the I i Ice and the method for
produci ng the carboxyl i c aci d- contai ni ng ni ckel powder.
BRI EF DESCRI PTI ON OF THE DRAW! NGS
[ 0023]
Fl G. 1 is a di agr am showi ng a conf i gurati on exampl e of a
cl assi f i er whi ch i s used to obtai n a f i ne powder havi ng an
extremely small number of coarse part i cl es usi ng a carboxyl i c aci d-
contai ni ng ni ckel powder of the present i nventi on.
MODE FOR CARRYING OUT THE INVENTION
[ 0024] Her ei naf t er , preferred
embodi ment s of the present
i nventi on will be descri bed i n detail .
[ 1] NI CKEL POWDER CONTAI NI NG CARBOXYLI C ACI D
First, the carboxyl i c aci d- contai ni ng ni ckel powder of the
present i nventi on will be descri bed.
[ 0025] The carboxyl i c acid-containing ni ckel
powder of the
present i nventi on contai ns a pl ural i ty of ni ckel parti cl es and has
a carboxyl i c aci d on a surf ace of each of the ni ckel part i cl es.
I n
other words, the carboxyl i c acid-containing ni ckel powder of the
CA 03174962 2022- 10-6
present i nventi on contains carboxyl i c aci d-
adsorbed ni ckel
part i cl es i n whi ch the carboxyl i c aci d i s adsorbed on the surf ace
of each of the ni ckel part i cl es as base parti cl es.
[ 0026]
For the carboxyl i c acid-containing ni ckel powder of the
present invention, by using a TG-MS
(Ther mogr avi met ry- Mass
Spectrometry), when a temperature i s rai sed from 38QC to 600QC at a
heating rate of 20 C/ mi n i n an i nert atmosphere, a peak i s detected
i n a mass chromatogram of a mol ecul ar i on of the carboxyl i c aci d.
Further, when a boil i ng poi nt of the carboxyl i c acid i s Tbp [ C] , a
peak top of the peak exi sts wi t hi n a range of ( Tbp
100) C or
hi gher and 600 C or I ower. Furthermore,
a cont ent of the
carboxyl i c aci d per 1 M2 of a surf ace area of the ni ckel part i cl e i s
155 pg or more and 450 pg or I ess.
[ 0027]
By sat i sf yi ng such condi ti ons, it is possi bi e to provi de
a carboxyl i c aci d- contai ni ng ni ckel powder
havi ng high
di spersi bi I i ty i n a gas phase and hi gh di spersi bi I i ty i n a paste
when used for f ormi ng the paste by mi xi ng with an organi c sol vent
and the I i ke. I n addi ti on, Si nce the di spersi bi I i
ty of the
carboxyl i c aci d- cont ai ni ng ni ckel
powder in the gas phase is
excel I ent,
coarse part i cl es can be suitably removed by dry
cl assi f i cat i on.
Further, t hi s makes it possi bi e to suitably obt ai n
a f i ne powder havi ng a sharp part i cl e size di stri but i on i n an
excel I ent yi el d by the dry cl assi f i cation or the I i ke.
Furthermore,
si nce the di spersi bi I ity of the carboxyl i c aci d- contai ni ng ni ckel
powder i n the paste contai ni ng the carboxyl i c aci d- contai fling
ni ckel powder i s excel I ent, it is possi bi e to i mprove smoothness of
a coati ng film formed by usi ng the paste.
[ 0028]
A value of the peak top of the peak in the mass
chromatogram of the mol ecul ar i on of the carboxyl i c aci d detected
by the TG-MS can be adj usted, for exampl e, by an adsorpti on form of
the carboxyl i c aci d onto the ni ckel part i cl e.
More speci f i call y,
for exampl e, the val ue of the peak top of the peak i n the mass
chromatogram of the mol ecul ar i on of the carboxyl i c aci d detected
by the TG-MS can be suitably adj usted by adj usti ng an adsorption
6
CA 03174962 2022- 10-6
met hod of the carboxyl i c aci d onto the ni ckel parti cl e, a condition
of adsorpti on treatment, an adsorpt i on amount or the I i ke.
[ 0029]
I n the present speci f i cat i on, the coarse parti cl es refer
to
parti cl es havi ng a suf f i ci ent I y large parti cl e di amet er
with
respect to a vol ume- based cumulative 50% particle diameter ( D50) of
a target powder whi ch may be a powder
obt ai ned by the
cl assi f i cat i on as descri bed above. For exampl e,
the coarse
parti cl es can be parti cl es havi ng the parti cl e diameter of 1.5
times or more with respect to the D50 of the target powder.
Further,
the coarse parti cl es can be parti cl es havi ng the parti cl e di ameter
of 2.0 times or more with respect to the D50 of the target powder.
Furthermore, the coarse parti cl es can be parti cl es havi ng the
parti cl e diameter of 2.5 times or more with respect to the D50 of
the target powder.
[ 0030] I n the present speci f i cat i
on, the vol ume- based
cumulative 50% parti cl e diameter (D50) refers to a vol ume- based
cumulative f racti on 50% val ue of the parti cl e size di stri but i on
measured usi ng the I aser- type parti cl e Si ze di stri but i on anal yzer
unl ess otherwise speci f i ed.
For exampl e, the vol ume- based
cumulative 50% parti cl e diameter (D50)
can be determi ned by
measurement usi ng a I aser di f f racti on/ scat t eri ng type parti cl e
size
di St ri but i on anal yzer LA- 960 ( manuf act ur ed by HORI BA) .
[ 0031]
For the TG-MS, STA2500 Regulus manufactured by NETZSCH
can be used as TG- DTA for raising a temperature of a sampl e.
I n
addi ti on, J MS- Q1500GC manufactured by J EOL Ltd. can be used as MS
for mass spectrometri c anal ysi s of substances vapor i zed by rai Si ng
the temperature of the sampl e.
[ 0032]
The content of the carboxyl i c acid per 1 m2 of the
surf ace area of the nickel particle constituting the carboxyl i c
ad i d- contai ni ng ni ckel powder can be obtai ned by measurement usi ng
a CS (Carbon and Sul fur)
anal yzer (for exampl e, EMI A- 320V
manufactured by HORI BA, Ltd. ) .
7
CA 03174962 2022- 10-6
[ 0033]
As descri bed above, in the carboxyl i c acid-containing
ni ckel powder of the present i nventi on, the peak appears i n a
predet ermi ned regi on ( (Tbp + 100) C or hi gher and 600 C or I ower),
which i s different from the boiling point of the carboxyl i c acid,
i n the mass chromatogram of the mol ecul ar i on of the carboxyl i c
acid in the analysis by the TG-MS.
This is thought to be due to
the carboxyl i c aci d bei ng adsorbed on the ni ckel part i cl e in a
speci fic form,
Al though the detailed mechanism is unknown, the
i nvent ors consi der it as f ol I ows. For exampl e,
i n a case of
chemi cal adsorpt i on where the carboxyl i c
acid is chemi call y
adsorbed on the ni ckel part i cl e,
the carboxyl i c aci d is more
st r ongl y adsorbed thereon compared with a case of physi cal
adsorpti on.
Therefore, it is presumed that the peak appears in a
hi gh temperature range of 100 C or hi gher than the boiling poi nt of
the carboxyl i c acid.
It is consi der ed that si nce the carboxyl i c
acid i s adsorbed on the ni ckel part i cl e i n the speci fic form and
the carboxyl i c aci d i s adsorbed on the surf ace of the ni ckel
part i cl e i n an appropri ate rat i o,
it is possi bl e to obtain the
above- ment i oned excel I ent effects.
That i s, it is consi dered that
the di spersi bi I i ty of the carboxyl i c aci d- contai ni ng ni ckel powder
i n the gas phase i s i mproved, and the di spersi bi I i ty thereof i n the
paste is improved when the carboxyl i c acid-containing ni ckel powder
i s used for f ormi ng the paste by mixing with the organi c sol vent
and the I i ke.
[ 0034]
Further, since the content of the carboxyl i c acid per 1
m2 of the surf ace area of the ni ckel parti cl e i s equal to or greater
than the I ower I i mi t val ue, the di spersi bi I i ty of the carboxyl i c
aci d- contai ni ng ni ckel powder i n the gas phase can be suf f i ci ent I y
excel I ent .
[ 0035]
Further, since the content of the carboxyl i c acid per 1
m2 of the surf ace area of the ni ckel part i cl e i s equal to or I ess
than the upper I i mi t val ue, the di spersi bi I i ty of the carboxyl i c
aci d- cont ai ni ng ni ckel
powder in the paste can be sufficiently
excellent when the carboxyl i c aci d- contai ni ng ni ckel powder is used
for f ormi ng the paste by mi xi ng with the organi c sol vent and the
I i ke.
8
CA 03174962 2022- 10-6
[ 0036]
I n the present speci f i cat i on, the "boil i ng poi nt" refers
to the boil i ng poi nt under 1 atm, that is, the normal boil i ng poi nt
unl ess ot herwi se speci f i ed.
[ 0037]
In a case where the carboxyl i c acid-containing ni ckel
powder contai ns a pl ur al i ty of ki nds of carboxyl i c aci ds, at I east
one car boxyl i c acid may satisfy the above- menti oned condi ti ons.
I n
part i cul ar,
it is preferable that the one havi ng the hi ghest
content among the pl ur al i ty of ki nds of car boxyl i c aci ds sat i sf i
es
the above condi ti ons.
More preferably, al I ki nds of carboxyl i c
aci ds contai ned i n t he car boxyl i c aci d- cont ai ni ng ni ckel
powder
sat i sf y the above condi ti ons.
[ 0038]
As descri bed above, in the carboxyl i c acid-containing
ni ckel powder of the present i nventi on, the peak top of the peak i n
the mass chromatogram of the mol ecul ar i on of the carboxyl i c aci d
detected by the above TG-MS analysis may exi St within the range of
(Tbp + 100) C or hi gher and 600 C or I ower.
It is prefer abl e t hat
the peak top exi sts wi t hi n the range of (Tbp + 120) C or hi gher and
580 C or I ower. .
It is more pref erabl e that the peak top exi sts
within the range of (Tbp + 150) C or hi gher and 560 C or I ower. .
It
i s even more pref erabl e that the peak top exi sts i n (Tbp + 200) C or
hi gher and 540 C or I ess.
It is most pref erabl e that the peak top
exi sts wi t hi n the range of (Tbp + 230) C or more and 520 C or lower.
As a result, the above-described effects are more remarkably
exhi bi t ed.
[ 0039]
In the carboxyl i c acid-containing ni ckel powder of the
present i nventi on, the content of the carboxyl i c aci d per 1 m2 of
the surf ace area of the ni ckel part i Cl e may be 155 pg or more and
450 g or I ess.
It is pr ef erabl e that the content i s 155 pg or
more and 400 pg or I ess.
It is more pref erabl e that the content i s
155 pg or more and 380 pg or I ess.
It is even more pref erabl e that
the content i s 155 pg or more and 350 pg or I ess.
I n part i cul ar,
i n the carboxyl i c aci d- contai fling ni ckel
powder of the present
i nventi on, the content of the carboxyl i c aci d per 1 m2 of the
surf ace area of the ni ckel part i cl e i s preferably 160 pg or more
9
CA 03174962 2022- 10-6
and 350 pg or I ess, more preferably 170 pg or more and 350 pg or
I ess, and even more pref erabl y 250 pg or more and 350 pg or I ess.
As a result, the above-described effects are more remarkably
exhi bi t ed.
[ 0040]
When the carboxyl i c acid-containing ni ckel powder of the
present invention is analyzed by the TG-MS as descri bed above, the
peak top of the peak i n the mass chromatogram of the mol ecul ar i on
of the carboxyl i c acid exi sts wi thi n the range of (Tbp + 100) C or
hi gher and 600 C or I ower.
I n addi ti on, an addi ti onal peak top of
the peak i n the mass chromatogram of the mol ecul ar i on of the
carboxyl i c aci d may exi St out si de the above range.
However, it is
pref erabl e that the addi ti onal peak top of the peak i n the mass
chromatogram of the mol ecul ar i on of the carboxyl i c aci d does not
exi St \Ail t hi n the range of (Tbp - 50) C or hi gher and ( Tbp + 50) C or
I ower.
[ 0041]
As a result, the di spersi bi I i ty of the carboxyl i c aci d-
contai ni ng ni ckel powder i n the gas phase can be further improved.
I n the case where the carboxyl i c acid-containing ni ckel powder
contai ns a pl ural i ty of ki nds of carboxyl i c aci ds, it is pref erabl e
that at least one carboxyl i c acid satisfies the above-mentioned
condi ti ons.
Further, it is more pref erabl e that the one havi ng the
hi ghest content among the pl ural i ty of ki nds of carboxyl i c aci ds
sat i sf i es the above- ment i oned condi ti ons.
Furthermore, it is even
more pref erabl e that al I ki nds of carboxyl i c aci ds contai ned i n the
carboxyl i c aci d- contai ni ng ni ckel
powder satisfy the above-
ment i oned condi ti ons.
[ 0042]
The vol ume- based cumul at i ve 50% part i cl e di ameter D50 of
the carboxyl i c aci d- contai ni ng ni ckel powder i s preferably more
than O. 01 pm and 10 pm or I ess, more preferably more than O. 03 pm
and 2.5 pm or less, even more preferably more than 0.05 pm and 1.2
pm or I ess, and most preferably more than O. 10 pm and 0.80 pm or
I ess.
[ 0043] [1- 1] NI CKEL PARTI CLES
CA 03174962 2022- 10-6
The ni ckel part i cl es constitute the mai n component of the
carboxyl i c aci d- contai ni ng ni ckel powder and each of the ni ckel
part i cl es i s mai ni y composed of ni ckel .
[ 0044]
The ni ckel part i cl e may be mai ni y composed of ni ckel .
For
exampl e, the ni ckel part i cl e may be composed of ni ckel as a
si ngl e metal , or may be composed of a ni ckel alloy.
1 n the ni ckel part i cl e,
the component with the hi ghest
content may be ni ckel , but the content of components other than the
ni ckel i n the ni ckel part i cl e i s preferably 40% by mass or less,
more preferably 30% by mass or I ess, and even more preferably 20%
by mass or less.
Among them, the content of the components other
than the ni ckel i n the ni ckel part i cl e i s preferably 10% by mass or
less, more preferably 5% by mass or less, and even more pref erabl y
1% by mass or I ess.
I n part i cul ar, the components other than the
ni ckel are pref erabl y cont al ned only as i nevi t abl e components i n
the ni ckel parti cl e.
I n this regard, the content of the components
other than the ni ckel i n the ni ckel part i cl e i s pref erabl y 1,000
ppm or less.
[ 0045] A shape of t he ni ckel
part i cl e i s not I i mi t ed, and
exampl es thereof i ncl ude spheri cal , flaky, granul ar, van i ous other
shapes, and a mixture of one or more sel ected therefrom.
[ 0046]
in this speci f i cat i on, the term "spheri cal" refers to a
part i cl e shape i n whi ch the r at i o of a I ong di ameter to a short
di ameter i s 2 or less.
The term "f 1 aky" refers to a shape i n whi ch
the rat i o of a long di ameter to a short di ameter exceeds 2.
[ 0047]
Examples of the method for producing the ni ckel particle
i ncl ude, but are not I i mi ted to, an el ectrol ysi s
method, an
at omi zat i on method, a mechani cal pulverization method,
a wet
r educt i on method, a spray pyrol ysi s method, a chemi cal
vapor
deposi ti on method, a physi cal vapor deposition method and the 1 i ke.
[ 0048] [1- 2] CARBOXYLI C ACI D
The carboxyl i c acid-containing ni ckel
powder contains the
carboxyl i c acid i n addi ti on to the ni ckel part i cl e.
11
CA 03174962 2022- 10-6
[ 0049]
Most of the carboxyl i c acid contai ned in the carboxyl i c
aci d- contai ni ng ni ckel powder is adsorbed on the surf ace of the
ni ckel part i cl e as the base part i cl e.
I n other words, most of the
carboxyl i c acid contai ned i n the carboxyl i c aci d- cont ai ni ng ni ckel
powder is contai ned as a component of the carboxyl i c acid-adsorbed
ni ckel part i cl e.
[ 0050]
The form of adsorpti on of the carboxyl i c acid onto the
ni ckel part i cl e can be either physi cal
adsorpti on or chemi cal
adsorpti on.
[ 0051]
The carboxyl i c aci d is not part i cul an y limited as I ong
as it is a compound havi ng a carboxyl group.
[ 0052]
The carboxyl i c aci d preferably has a boil i ng poi nt of
100 C or hi gher and 270 C or I ower, more pref erabl y 105 C or hi gher
and 250 C or I ower, even more pref erabl y 110 C or hi gher and 200 C
or I ower, and most pref erabl y 115 C or hi gher and 170 C or I ower.
[ 0053]
As a result, the di spersi bi I i ty of the carboxyl i c acid-
contai ni ng ni ckel powder i n the gas phase can be further improved.
I n addi ti on, when the carboxyl i c acid-containing ni ckel powder is
used for f ormi ng the paste by mi xi ng with the organi c sol vent and
the I i ke,
the di spersi bi I i ty of the carboxyl i c aci d- cont ai ni ng
ni ckel powder i n the paste can be further improved.
I n the
production of the carboxyl i c aci d- contai ni ng ni ckel powder, the
carboxyl i c aci d as a raw mat en i al can be sui tabl y handl ed i n a
I i qui d state, thereby i mprovi ng the handl i ng property.
Further,
when the carboxyl i c aci d in a vapori zed state i s adsorbed on the
ni ckel powder, the carboxylic acid can be adsorbed on the ni ckel
powder i n a more sui tabl e state.
[ 0054]
The carboxyl i c aci d i s pref erabl y a monocarboxyl i c aci d.
Thus, the di spersi bi I i ty of the carboxyl i c acid-containing
ni ckel powder i n the gas phase can be further i mproved.
I n
addi ti on, when the carboxyl i c aci d- contai ni ng ni ckel powder is used
for f ormi ng the paste by mi xi ng with the organi c sol vent and the
12
CA 03174962 2022- 10-6
like, the di spersi bi I i ty of the carboxylic acid-containing ni ckel
powder i n the paste can be further improved.
[ 0055] The molecular wei ght of the carboxyl i c
acid is
preferably 40 or more and 160 or I ess, more preferably 50 or more
and 120 or I ess, and even more pref erabl y 55 or more and 100 or
I ess.
[ 0056] Thus, the di spersi bi I ity
of the carboxyl i c aci d-
contai ni ng ni ckel powder i n the gas phase can be further improved.
I n addi t i on, when the carboxyl i c aci d- contai ni ng ni ckel powder i s
used for f ormi ng the paste by mi xi ng with the organi c sol vent and
the I i ke,
the di spersi bi I i ty of the carboxyl i c aci d- cont ai ni ng
ni ckel powder i n the paste can be further i mproved.
[ 0057]
The number of carbon atoms of the carboxyl i c acid is
preferably 2 or more and 9 or I ess, more preferably 2 or more and 7
or I ess, and even more pref erabl y 2 or more and 5 or I ess.
[ 0058] Thus, the di spersi bi I ity
of the carboxyl i c aci d-
contai ni ng ni ckel powder i n the gas phase can be further improved.
I n addi ti on, when the carboxyl i c acid-containing ni ckel powder is
used for f ormi ng the paste by mi xi ng with the organi c sol vent and
the I i ke,
the di spersi bi I i ty of the carboxyl i c aci d- cont ai ni ng
ni ckel powder i n the paste can be further i mproved.
[ 0059]
Exampl es of the carboxyl i c aci d i ncl ude f ormi c aci d,
acetic acid, propi oni c aci d, i sobut yr i c
aci d, but yr i c acid,
crot oni c aci d, i soval en i c aci d, val en i c aci d, caproi c aci d,
enant hi c
aci d, capryl i c aci d, pel argoni c aci d,
I act i c aci d, oxal i c aci d,
succi ni c aci d, ol ei c aci d, acryl i c aci d, met hacryl i c aci d and the
I i ke.
One or a combi nat i on of two or more sel ected from these can
be used.
It is preferable that the carboxyl i c aci d i s at I east one
sel ected from the group consi st i ng of the aceti c aci d and the
propi oni c aci d.
It is more pref erabl e that the carboxyl i c aci d i s
the acetic acid.
13
CA 03174962 2022- 10-6
[ 0060] Thus, the di spersi bi I ity of the
carboxyl i c acid-
contai ni ng ni ckel powder i n the gas phase can be further i mproved.
I n addi ti on, when the carboxyl i c acid-containing ni ckel powder is
used for f ormi ng the paste by mi xi ng with the organi c sol vent and
the I i ke,
the di spersi bi I i ty of the carboxyl i c aci d- cont ai ni ng
ni ckel powder i n the paste can be further i mproved.
[ 0061] [ 1- 3] USE OF CARBOXYLI C Ad I D- CONTAI NI NG NI CKEL POWDER
The use of the carboxyl i c aci d- contai ni ng ni ckel powder of
the present i nventi on i s not parti cul arly limited, but may be used
as a conduct i ve powder.
I n parti cul ar, the carboxyl i c aci d-
contai ni ng ni ckel powder is preferably used as a conductive powder
for a conductive paste.
Si nce the di spersi bi I i ty as the powder i s
hi gh, the di spersi bi I i ty i n the paste tends to be hi gh.
I n
parti cul ar, the carboxyl i c aci d- contai fling ni ckel
powder of the
present i nventi on i s pref erabl y used as the conductive powder and
more preferably used as the conductive powder for the conductive
paste after bei ng subj ect ed to a cl assi f i cat i on step, especi ally
after bei ng subj ected to a step of dry cl assi f i cat i on as descri bed
I at er.
Si nce the carboxyl i c aci d- contai ni ng ni ckel powder has hi gh
f I ui di ty and excel I ent handl i ng property, the ni ckel powder can be
easi I y handl ed i n the case of
bei ng subj ect ed to van i ous
appl i cat i ons.
[ 0062]
By subjecting the carboxyl i c acid-containing ni ckel
powder of the present i nventi on to the step of dry cl assi f i cat i on
as descri bed bel ow, it is possi bl e to sui tabl y obtai n a fi ne powder
which has a smal I average parti cl e di ameter, a narrow parti cl e size
di st ri but i on, and contai ns al most no coarse parti cl es.
Such a f i ne
powder has a narrower
parti cl e si ze di stri but i on than the
carboxyl i c aci d- contai ni ng ni ckel powder of the present i nvent i on
before cl assi f i cat i on, and thus the f i ne powder can form a coati ng
film havi ng more excel I ent smoothness.
Further, when the f i ne
powder i s used for an i nternal el ect rode, the f i ne powder can form
an electrode I ayer havi ng a uni form t hi ckness.
Si nce al most no
coarse parti cl es are contai ned therei n, it is possi bi e to suitably
prevent the conductive powder parti cl es from comi ng i nt o contact
with both the i nternal el ectrodes and causi ng a short ci rcui t.
14
CA 03174962 2022- 10-6
Therefore,
even i n appl i cat i ons where such hi gh rel i abi I i ty i s
r equi red,
a suf f i ci ent I y sat i sf act or y effect can be obt ai ned.
Therefore, when the f i ne powder i s used for f or mi ng i nt er nal
conductors (internal el ect r odes) and t ermi nal
electrodes of a
multi I ayer cerami c el ect roni c component
such as a multi layer
cerami c capacitor, a mul ti I ayer cerami c i nduct or and a multi I ayer
pi ezo el ect r i c actuator, the above- descri bed effect
i s more
remarkably exhi bi t ed.
[ 0063]
The conductive powder may be used for forming conductive
port i ons of el ect roni c components, for example, as a conductive
paste by mi xi ng with a gl ass f ri t and an or gani c vehi cl e.
[ 0064]
METHOD FOR PRODUCI NG CARBOXYLI C ACI D- CONTAI NI NG NI CKEL
POWDER
Next, a met hod for produci ng the carboxyl i c aci d- cont ai fling
ni ckel powder accordi ng to the present i nvent i on will be descri bed.
[ 0065]
The method of the present invention for produci ng a
carboxyl i c acid-containing ni ckel powder is a method for produci ng
the carboxyl i c acid-containing ni ckel powder of
the present
i nvent i on descri bed above.
The method i ncl udes a step of bri ngi ng
the carboxyl i c aci d in a gaseous state i nto contact with the ni ckel
powder whi ch i s an aggregate of the pl ural i ty of ni ckel part i cl es
di spersed i n a gas phase.
[ 0066]
As a result, it is possi bl e to provi de the method for
produci ng the carboxyl i c aci d- contai ni ng ni ckel powder havi ng hi gh
di spersi bill ty i n the gas phase and hi gh di spersi bill ty i n the
paste when the carboxyl i c aci d- cont ai ni ng ni ckel powder i s used for
f ormi ng the paste by mi xi ng with an organi c sol vent and the I i ke.
Further, as compared with a case where the carboxyl i c aci d i n the
gaseous state is brought i nto contact with the ni ckel powder i n a
stat i onary state, the carboxyl i c acid can be adsorbed on the
surf ace of each of the ni ckel part i cl es i n an overwhel mi ngl y short
time with lower concent rat i on thereof. Therefore,
it is
advantageous from the vi ewpoi nt of consumpti on of the carboxyl i c
acid and shorteni ng of time.
CA 03174962 2022- 10-6
[ 0067]
The method for producing the carboxyl i c aci d- contai fling
ni ckel powder accordi ng to the present i nventi on may have the step
of bri ngi ng the carboxyl i c aci d in the gaseous state i nto contact
with the ni ckel powder di spersed i n the gas phase.
However, for
exampl e, it is pref erabl e to di sperse the ni ckel powder, whi ch i s
the aggregate of the pl ur al i ty of ni ckel part i cl
es, i n an
atmosphere contai ni ng the carboxyl i c aci d in the gaseous state.
[ 0068] In the method for
produci ng the carboxyl i c aci d-
cont ai ni ng ni ckel powder accordi ng to the present i nventi on, under
the condi ti on that the ni ckel powder bei ng i n a di spersed state i n
a gas phase at the ti me of gener at i on has been di spersed i n the gas
phase, a step of bri ngi ng the carboxyl i c aci d in the gaseous state
i nto contact with the ni ckel powder may be performed by suppl yi ng
the carboxyl i c aci d in the gaseous state (carboxyl i c acid gas) i nto
the gas phase.
[ 0069]
I n thi s way, after the ni ckel powder i s generated i n the
gas phase, the carboxyl i c aci d gas can be brought i nto contact with
the ni ckel powder havi ng a better di spersed state by suppl yi ng the
carboxyl i c aci d gas i nto the gas phase before coil ect i ng the ni ckel
powder.
Thus, the carboxyl i c aci d can be more uni f orml y adsorbed
on the ni ckel powder.
[ 0070]
Examples of the method of generating the ni ckel powder
bei ng i n the di spersed state in the gas phase at the ti me of
generati on i ncl ude: a gas phase method such as a chemi cal vapor
deposi ti on met hod and a physi cal vapor deposi ti on method; an
at omi zat i on method; a spray pyrol ysi s method; and the I i ke.
I n
part i cul ar, by gener at i ng the ni ckel powder usi ng the gas phase
method or the spray pyrol ysi s method, it is possi bl e to more easi I y
adj ust the part i cl e di amet er of the ni ckel powder so as to be a
sui t abl e condi ti on.
[ 0071] In the met hod for
pr oduci ng the carboxyl i c aci d-
cont ai ni ng ni ckel powder accordi ng to the present i nventi on, the
method may have the step of bri ngi ng the carboxyl i c aci d in the
16
CA 03174962 2022- 10-6
gaseous state i nto contact with the ni ckel powder di spersed i n the
gas phase.
It is not I i mi ted to the method of bringing the
carboxyl i c acid in the gaseous state i nto contact with the ni ckel
powder i mmedi at el y after producti on of the ni ckel powder.
For
exampl e, the carboxyl i c acid in the gaseous state may be brought
i nto contact with the ni ckel powder coil ected once.
[ 0072]
[ 3] METHOD FOR PRODUCI NG Fl NE POWDER USI NG CARBOXYLI C
ACI D-CONTAI Ni NG Ni CKEL POWDER OF THE PRESENT I NVENTI ON
Next, a method for produci ng a f i ne powder usi ng the above-
ment i oned carboxyl i c aci d- contai ni ng ni ckel powder of the present
i nvent i on will be descri be.
[ 0073]
A method for produci ng a fine powder according to the
present embodi ment is a method for produci ng a f i ne powder havi ng a
vol ume- based cumul at i ve 50% part i cl e di ameter D50 Wi t hi n a range
of
0.01 pm or more and 5. 0 pm or I ess.
The method i ncl udes: a step of
generating a powder to be classified by dispersing a carboxylic
aci d- contai ni ng ni ckel powder havi ng D5o of more than 0.01 pm and 10
pm or I ess i n a gas phase; and a step of dry cl assi fyi ng the powder
to be classified.
[ 0074]
As a result, it i s possi bl e to provi de the method for
produci ng the fine powder whi ch i s capable of produci ng the fine
powder havi ng an extremely smal I number of coarse part i cl es and
havi ng the vol ume- based cumul at i ve 50% part i cl e di ameter D50 wi t hi
n
a range of 0. 01 pm or more and 5.0 pm or I ess with hi gh
productivity.
[ 0075]
Such excellent effects can be obtai ned by the following
reasons.
That i s, as compared with the case of perf ormi ng the dry
cl assi f i cat i on by adsorbi ng an auxi I i ary agent such as ethanol onto
the powder, the di spersi bi I i ty of the powder in the gas phase i s
i mproved and the cl assi f i cat i on accuracy i s enhanced by usi ng the
carboxyl i c aci d- contai ni ng ni ckel powder in which the carboxyl i c
acid i s adsorbed on each of the ni ckel
part i cl es under a
predetermi ned condi ti on.
Therefore, the number of coarse part i cl es
contai ned i n the produced f i ne powder can be extremely reduced.
I n
17
CA 03174962 2022- 10-6
addi ti on, it is possi bl e to reduce the number of cl assi f i cat i on,
thereby i mpr ovi ng pr oduct i vi ty.
[ 0076]
When the fine powder obtai ned as descri bed above is
mixed with an organi c sol vent and the I i ke to form a paste, the
di spersi bi I i ty of the f i ne powder i n the paste is part i cul an y
excel I ent .
Therefore, the smoothness of a coati ng film formed
using the paste can be improved.
[ 0077]
I n addi ti on, by usi ng the carboxyl i c aci d- contai ni ng
ni ckel powder of the present i nvent i on, the f I ui di ty of the powder
i s enhanced, the adhesi on of the powder to a cl assi f i er i s reduced,
and the yi el d is improved.
Further, si nce the adhesi on to the
cl assi f i er i s reduced, a powder supply port and an i nsi de of the
pi pi ng in the cl assi f i er are hardly clogged, so that the operati on
ti me of the classifier is extended and the productivity is improved.
[ 0078]
In addi ti on, in the present embodi ment , the carboxyl i c
aci d- contai ni ng ni ckel
powder i n whi ch the carboxyl i c acid i s
adsorbed on each of the ni ckel
parti cl es i n advance under a
predetermi ned condi ti on i s used.
Thi s i s advantageous i n terms of
si mpl i fyi ng and downsi zi ng a structure of an apparatus used for
produci ng the f i ne powder. Further, as compared with a case where a
ni ckel powder on whi ch a carboxyl i c aci d i s not adsorbed i s put i n
a di spersi ng machi ne, the f I ui di ty of the powder becomes hi gher. I n
addi ti on, the adhesi on of the powder i n the di spersi ng machi ne i s
I ess I i kel y to occur.
As a result, the movement of the powder i n
the di spersi ng machi ne becomes smoother.
Thi s i s al so because the
carboxyl i c aci d- contai ni ng ni ckel powder in whi ch the carboxyl i c
aci d i s adsorbed on each of the ni ckel part i cl es i n advance under a
predetermi ned condi ti on i s used.
[ 0079]
in this speci f i cat i on, the "cl assi f i cat i on" refers to an
oper at i on of cl assi f yi ng the powder i nt o a group of r el at i vel y
large part i cl es (in other words, coarse powder) and a group of
relatively small particles (i n other words, fine
powder).
Speci f i call y, i n the present speci f i cat i on, the fine powder refers
to
a group of part i cl es havi ng a vol ume- based cumulative 50%
18
CA 03174962 2022- 10-6
part i cl e di ameter D50 wi t hi n a range of 0.01 pm or more and 5.0 pm
or I ess. Further, the coarse powder refers to a group of parti cl es
havi ng a I arger D50 than that of the f i ne powder.
[ 0080] [ 3- 1] CLASSI Fl ER
FIG. 1 i s a di agram showi ng a conf i gurati on exampl e of a
cl assi f i er whi ch i s used to obtai n a f i ne powder havi ng an
extremely small number of coarse part i cl es usi ng a carboxyl i c aci d-
contai ni ng ni ckel powder of the present i nventi on.
I n the foil owi ng descri pti on, the upper side i n FIG. 1 is
ref erred to as "upper" and the lower si de i n FIG. 1 i s ref erred to
as "1 ower".
[ 0081]
A classifier 1 is an ai rf I ow classifier which performs
cl assi f i cati on usi ng centrifugal force act i ng on the powder.
The
cl assi f i er 1 i ncl udes a casi ng 3 which forms a cl assi f i cati on
chamber 10.
[ 0082]
At the upstream side of the cl assi f i cati on chamber
( cl assi f i cati on zone) 10, there is a dispersion zone 11 where the
carboxyl i c aci d-contai ni ng ni ckel
powder is di spersed pri or to
cl assi f i cati on. The cl assi f i cation chamber 10 i s the area where the
dispersed carboxyl i c acid-containing ni ckel powder is classified.
[ 0083] The classifier 1 has an introduction port
4 for
i ntroduci ng the carboxyl i c aci d- contai ni ng ni ckel powder i nto the
di spersi on zone 11, an ai r nozzl e 5 that i nj ects hi gh- pressure ai r
( pri mary ai r) i nto the di spersi on zone 11, a gui de vane 6 to
i ntroduce secondary air to fl ow i nto the cl assi f i cati on chamber 10
to form a swi rl i ng ai rf I ow in the cl assi f i cati on chamber 10, a f i
ne
powder di scharge port 7 that has an openi ng at the upper center of
the cl assi f i cati on chamber 10, and a coarse powder di scharge port 8
that has an openi ng along the lower per i phery of the classification
chamber 10.
[ 0084]
Next, the method for dispersing and classifying the
carboxyl i c aci d- contai ni ng ni ckel powder usi ng such a cl assi f i er 1
will be descri bed.
19
CA 03174962 2022- 10-6
[ 0085] The carboxyl i c aci d- contai fling ni
ckel powder is
i ntroduced i nto the di spersi on zone 11 from the i ntroduct i on port 4.
The
carboxyl i c aci d- contai ni ng ni ckel powder is di spersed by a
di spersi ng force imparted by the pri mary ai r i nj ected i nto the
di spersi ng zone 11.
Then, the carboxyl i c aci d- contai ni ng ni ckel
powder i s introduced i nto the cl assi f i cat i on chamber 10 i n a
di spersed state.
[ 0086]
I n the cl assi f i cat i on chamber 10, the secondary ai r i s
f I own t herei n through the gui de vane 6, whi ch ai rf I ow i s swi rl ed i
n
the cl assi f i cati on chamber 10 and i s exhausted from the upper
center of the cl assi f i cat i on chamber 10.
An outward centrifugal
force exerted by the swi r I i ng ai rf I ow and a central I y- di rect ed
ai rf I ow separate the carboxyl i c aci d- contai ni ng ni ckel powder i n
the solid-gas mixture i nto a coarse powder and a f i ne powder.
[ 0087]
The coarse powder moves radi ally outward in the
cl assi f i cat i on chamber 10 due to the outward centrifugal force of
the
swi r I i ng ai rf I ow, and i s coil ected from the coarse powder
di schar ge port 8 on the I ower per i phery of the cl assi f i cat i on
chamber 10.
On the other hand, the fine powder moves radi ally
i nward i n the classification chamber 10 due to the central I y-
di rect ed ai rf I ow, and i s col I ected from the f i ne powder discharge
port 7 at the upper center of the cl assi f i cat i on chamber 10.
[ 0088]
A suction pump (not shown i n the figure) is connected to
the f i ne powder di scharge port 7. The fine powder is discharged and
coil ected together with the ai r ( exhaust air) i n the classification
chamber 10.
[ 0089]
The step of generating a powder to be classified
corresponds to the step performed i n the di spersi on zone 11, and
the step of dry cl assi f i cat i on corresponds to the step performed i n
the cl assi f i cat i on chamber (cl assi f i cat i on zone) 10.
That is, the carboxyl i c aci d- contai ni ng ni ckel powder in a
di spersed state i n the di spersi on zone 11, or i n other words, the
carboxyl i c acid-containing ni ckel powder introduced
into the
CA 03174962 2022- 10-6
classification chamber 10, is the powder to be cl assi f i ed i n this
speci f i cat i on.
[ 0090]
In the above expl anat i on, the airflow classifier that
uses the centrifugal
force from the swi r I i ng airflow for the
cl assi f i cat i on i s used as an exampl e, but the cl assi f i cat i on met
hod
of
a cl assi f i er is not limited to any part i cul ar method. For
exampl e, a cl assi f i cat i on met hod for uti I i zi ng centrifugal force
due
to rotation of a rotor, a cl assi f i cat i on met hod for using
gravity, and a cl assi f i cat i on met hod for usi ng i nert i al force may
be used.
[ 0091]
In the present invention, the step of generating a
powder to be classified and the step of dry cl assi f i cat i on are not
I i mi ted to the case where the same equi pment i s used, and may be
performed usi ng separate equi pment.
I n other words, the powder to
be cl assi f i ed may be obtai ned by di spersi ng the carboxyl i c aci d-
contai ni ng ni ckel powder i n a di spersi ng machi ne,
and then
cl assi f yi ng the powder to be cl assi f i ed i n a dry cl assi f i er.
[ 0092] [ 3- 2] STEP OF GENERATI NG POWDER TO BE CLASSI Fl ED
I n
the step of generati ng a powder to be cl assi f i ed, the
powder to be cl assi f i ed i n which the carboxyl i c acid-containing
ni ckel powder i s di spersed i n the gas phase i s obtai ned.
[ 0093]
The supply speed of the carboxyl i c acid-containing
ni ckel powder to the cl assi f i er, that i s, for exampl e, the supply
speed of the carboxyl i c aci d- cant ai ni ng ni ckel
powder from
I ntroducti on port 4 i nto the di spersi on zone 11 i n the cl assi f i er 1
shown i n Fl G. 1 depends on the si ze (capacity) of the cl assi f i er 1.
However, it is preferably 1 kg/ hr or more and 20 kg/ hr or I ess,
more preferably 3 kg/ hr or more and 15 kg/ hr or less, and even more
preferably 5 kg/ hr or more and 12 kg/ hr or less.
[ 0094]
As a result, the di spersi bi I i ty of the carboxyl i c aci d-
contai ni ng ni ckel powder can be improved, and the product i vi ty of
the f i ne powder can be further improved.
21
CA 03174962 2022- 10-6
[ 0095] The suppl yi ng and di spersi ng pressure dun i ng di
spersi on,
that i s, for exampl e, the pressure of the di spersed ai r i nj ected
from the ai r nozzl e 5 i nto the di spersi on zone 11 i n the cl assi f i er
1 shown i n FIG. 1 i s not parti cul an y I i mi ted, but i s preferably
O. 2 MPa or more and 1. 0 MPa or I ess, more preferably 0.4 MPa or
more and 0.8 MPa or I ess, and st i I I more preferably 0.5 MPa or more
and O. 7 MPa or I ess.
[ 0096] As a result, the di spersi bi I i ty of the carboxyl i
c aci d-
contai ni ng ni ckel powder can be improved, and the producti vi ty of
the f i ne powder can be further improved.
[ 0097] [ 3- 2] STEP OF DRY CLASS! Fl CATI ON
I n the step of dry cl assi f i cat i on, the powder
to be
cl assi f i ed obt ai ned i n the step of gener at i ng the powder to be
classified is dry cl assi f i ed.
[ 0098] Because the powder to be classified is suitably
di spersed i n the gas phase, the cl assi fi cati on accuracy i n the step
of dry cl assi f i cat i on i s
improved. Consequently, the number of
coarse part i cl es i n the produced f i ne powder can be extremely
reduced.
I n addi ti on, the improved cl assi f i cat i on accuracy can
reduce the number of ti mes of cl assi f i cat i
ons to improve
productivity.
[ 0099] As the fluidity of the powder to be classified is
i ncr eased, adhesi on of the powder to be cl assi f i ed to an i nsi de of
the cl assi f i er will be reduced, whi ch improves the yi el d.
As the
adhesi on of the powder to be cl assi f i ed to the i nsi de of the
cl assi f i er is reduced, blockage of a powder supply port and an
I nsi de of piping of the classifier hardly occur, thereby extending
the operati on ti me of the cl assi f i er.
Thus, the productivity i s
I ncr eased.
[ 0100] Thus, the fine powder containing the extremely smal I
number of coarse part i cl es can be produced with a hi gh producti vi ty.
22
CA 03174962 2022- 10-6
[ 0101]
A gas phase temperature at which the step of dry
cl assi f i cat i on i s performed i s not I i mi t ed, and preferably ranges
from 60 C to 300 C, more preferably from 100 C to 250 C, and even
more preferably from 150 C to 200 C.
[ 0102]
I n the ranges, probl ems such as def ormati on of part i cl es
by heat and al t er at i on of constituent mat er i al s of the part i cl es
are prevented more eff ect i vel y.
At the same time, the centrifugal
force is increased due to a hi gher speed of the ai rf I ow.
I n
addi ti on, it is possi bl e to prevent water vapor from adheri ng to
the part i cl es, thereby further enhanci ng
the classification
accuracy. The productivity can al so be further improved.
In
addi ti on, the number of coarse part i cl es i n the f i ne powder can be
part i cul ar I y reduced.
[ 0103]
A suct i on ai rf I ow amount during the step of dry
cl assi f i cat i on, i . e. , for example, a suct i on ai rf I ow amount by
the
suction pump connected to the f i ne part i cl e di scharge port 7 i n the
cl assi f i er 1 shown i n FIG. 1, is not limited, and preferably ranges
from 5.0 m3/ mi n to 30 m3/ mi n, more pref er abl e from 6.0 m3/ mi n to 20
m3/mi n, and even more preferably from 7. 0 m3/ mi n to 9.0 m3/ mi n.
I n these ranges, more eff i ci ent cl assi f i cat i on of the powder
to be classified can be achieved.
[ 0104]
A suction pressure at which dry classification is
performed, i . e. , for exampl e, a suct i on pressure by the suct i on
pump connected to the f i ne part i cl e di scharge port 7 i n the
cl assi f i er 1 shown i n FIG. 1, is not limited, and preferably ranges
from -60 kPa to -5 kPa, more preferably from -50 kPa to -10 kPa,
and even more preferably from -40 kPa to -15 kPa.
I n these ranges,
a more eff i ci ent classification of the
powder to be classified can be achieved.
[ 0105]
By the dry classification, the powder to be classified
i s classified i nto a f i ne powder and a coarse powder. The powder to
be
cl assi f i ed i s cl assi f i ed i nt o, f or exampl e, t he f i ne
powder
havi ng the vol ume- based cumul at i ve 50% part i cl e di ameter D50 rangi
ng
from O. 01 pm to 5. 0 pm, and the coarse powder havi ng the D50 I arger
23
CA 03174962 2022- 10-6
than that of the f i ne powder.
Among them, the fine powder is
coil ect ed as the fine powder produced.
[ 0106]
As descri bed above, the f i ne powder having the vol ume-
based cumul at i ve 50% part i cl e diameter D50 rangi ng from 0.01 pm to
5.0 pm i s produced.
[ 0107]
The fine powder produced i n this way has the extremely
smal I number of coarse part i cl es. I n addi
ti on, secondary
aggregat i on i s prevented, si nce the carboxyl i c aci d i s adsorbed on
the f i ne powder i n a sui tabl e state.
[ 0108]
Furthermore, the method as descri bed above can reduce
the
number of times of cl assi f i cat i ons due to the improved
classification accuracy.
Further, adhesion of the powder to be
cl assi f i ed to i nsi de the cl assi f i er i s al so reduced,
thereby
i ncreasi ng the yi el d.
I n addi ti on, the reduced adhesi on i nsi de the
classifier prevents blockage of the powder supply port and the
i nsi de of the pi pi ng of the classifier, thereby extending the
oper at i on ti me of the cl assi f i er and i mpr ovi ng pr oduct i vi ty.
[ 0109]
The step of dry classification may be performed only
once or repeated multi pl e times, whi ch enabl es to further enhance
the cl assi f i cat i on accuracy.
[ 0110]
A yield of fine powder in the step of dry classification
i s not I i mi ted, and i s pref erabl y 80% or hi gher, more preferably
81% or hi gher, and even more preferably 82% or hi gher, and most
preferably 83% or more.
Thus, the effects of the pr event
i nvent i on are more
remarkably exhi bi t ed.
[ 0111]
In this speci f i cat i on, the yield of fine powder in the
step of dry cl assi f i cat i on is cal cul at ed from a wei ght of the
powder before cl assi f i cat i on,
i . e. , a wei ght of the carboxyl i c
aci d- contai ni ng ni ckel powder, and a wei ght of the powder after
cl assi f i cat i on, i . e. , a wei
ght of the f i ne powder, usi ng the
foil owi ng f or mul a:
24
CA 03174962 2022- 10-6
Yi el d (/0) = (wei ght of powder after cl assi f i cat i on / wei ght
of powder before cl assi f i cat i on) x 100
[ 0112]
The fine powder produced by the method according to the
present
i nventi on as descri bed above have the vol ume- based
cumul at i ve 50% part i cl e di ameter 050 rangi ng from 0.01 pm to 5.0 pm.
Pref erabl y, the D50 of the f i ne powder ranges from 0.03 pm to 2.0 pm,
more pref erabl y from 0.05 pm to 1.0 pm, and even more pref erabl y
from 0.10 pm to 0.60 pm.
[ 0113] Thus, the fine powder with an i deal
part i cl e size
di st ri but i on can be obtai ned.
Convent i onal I y, when the D50 was
wi t hi n such a range, a probl em of coarse part i cl es is li kel y to
occur to cause adverse effects. I n contrast, the present i nventi on
can prevent the occurrence of such a probl em more eff ecti vel y even
when the D50 i s wi t hi n the range.
That i s, the effects of the
present i nventi on are more remarkabl y exhi bi ted when the D50 of the
fine powder is within the above range.
[ 0114]
The fine powder produced by the method according to the
present i nventi on as descri bed above pref erabl y has a val ue of ( D90
-
D10) / D50 rangi ng from 0.30 to 0.90, more preferably from 0.35 to
0.80, and sti I I more pref erabl y from 0.40 to 0.75, wherein Dio [ pm]
i s a part i cl e di ameter at vol ume- based cumul at i ve f r act i on 10%,
D50
[ pm] i s a part i cl e di ameter at vol ume- based cumul at i ve f r act i on
50%,
and
D90 [ pm] i s a part i cl e di ameter at vol ume- based cumul at i ve
f racti on 90% of a part i cl e size di st ri but i on measured by a I aser
part i cl e size anal yzer.
[ 0115]
The val ue of ( D90- D10)/ D50 i s an i ndex of a uni f ormi ty of
the part i cl e size di st ri but i on.
A smal I er val ue of ( D90- D10)/1)50
i ndi cat es a narrower part i cl e Si ze di st ri but i on, i . e. , more uni
form
part i cl e size.
[ 0116]
Thus, the f i ne powder has more uni form part i cl e si ze and
i s used sui tabl y for van i ous appl i cat i ons.
CA 03174962 2022- 10-6
[ 0117]
In the met hod for producing the fine powder, the number
of
coarse part i cl es, as determi ned by the f ol I owi ng measurements,
i s preferred 30 or I ess, more pref erabl y 25 or I ess, and even more
preferably 20 or I ess.
[ 0118]
In such cases, van i ous probl ems caused by the presence
of
coarse part i cl es i n the f i ne powder can be prevented more
ef f ect i vel y.
[ 0119]
The above measurement of the coarse particle count can
be performed, for exampl e, as f ol I ows.
Fi rst I y, a di spersi on I i qui d of the f i ne powder is prepared by
mi xi ng 1.0 g of the f i ne powder with 20 ml of ethanol whi ch mixture
i s then treated with an ul t r as oni c
cl eaner ( e. g. , W- 113
manufactured by Honda El ect r oni cs Co., Ltd. )
for 1 mi flute.
Subsequently, 30 I of the di spersi on I i quid prepared i s sampled
and then dropped onto an al umi num sampl e stand, whi ch i s dr i ed to
remove the di spersi on medi um. Thereby, a sampl e for measurement i s
prepared. The sampl e thus prepared i s observed by usi ng a scanni ng
electron microscope ( e. g. , SU- 1510 manufactured by Hitachi Hi gh-
Tech Corpor at i on) for 50 f i el ds of vi ew at a magni f i cat i on of
10, 000 times.
The total number of particles having a diameter 1.5
times or greater than the vol ume- based cumulative 50% particle
di amet er D50 of the f i ne powder i s counted as the coarse part i cl e
count.
[ 0120]
The suitable embodi ment s of the present invention have
been descri bed above, but the present i nventi on i s not limited to
these.
[ 0121]
For exampl e, the equi pment sui t abl y used i n the met hod
for
produci ng the f i ne powder of the present i nvent i on i s not
limited to those descri bed i n the af or ement i oned embodi ment s.
EXAMPLES
[ 0122]
The present i nvent i on i s descr i bed i n more detail with
sped i f i c exampl es bel ow, but the present i nvent i on is not limited
onl y to the f ol I owi ng exampl es.
I n the f ol I owi ng expl anati ons,
26
CA 03174962 2022- 10-6
treatments for whi ch no part i cul ar temperature or
humi di ty
condi t i ons are indicated were conducted at room temperature ( 25 C)
and a relative humi di ty of 50%. I n addi ti on,
the van i ous
measurement condi ti ons, unl ess ot her wi se i ndi cat ed, are those at
room temperature ( 25 C) and a relative humi di ty of 50%. The vol ume-
based cumul at i ve f r act i on 10% val ue Dio, the vol ume- based cumul at i
ve
f r act i on 50% val ue D50, and t he vol ume- based cumul at i ve f r act i
on 90%
val ue D90 were measured for the carboxyl i c aci d- cont ai ni ng ni ckel
powder and the f i ne powder usi ng a I aser di f f r act i on/ scat t er i ng
particle size anal yzer LA-960 (manufactured by HORI BA Lt d. )
The condi ti ons of the carboxyl i c aci ds used i n each of the
foil owi ng exampl es are summari zed i n Tabl e 1.
[ 0123] [Tabl e 1]
Table 1
Carboxylic acid Boiling point [CC] Molecular -weight Carbon number
Acetic acid (AA) 118.5 60.05 2
Propiomic (PA) 141 74.9
[ 0124]
[ 4] PRODUCTI ON OF CARBOXYLI C ACI D- CONTAI NI NG NI CKEL
POWDER
Exampl e 1
First, a ni ckel powder having a volume-based cumulative 50%
part i cl e di amet er 050 of 0.31 pm was prepared.
The ni ckel powder was di spersed i n an atmosphere cont ai ni ng
an
acet i c aci d as a car boxyl i c aci d for 10 seconds, thereby
obt ai ni ng a carboxyl i c aci d- contai ni ng ni ckel powder which was an
acetic aci d- adsor bed ni ckel powder.
The acetic acid with a purity
close to 100% ( speci al grade 99. 7+% manufactured by Fuj ifilm Wako
Pure Chemi cal Cor por at i on) was used.
I n addi ti on, the temperature
of the atmosphere contai ni ng the aceti c acid was adj usted to 100 C
when the ni ckel powder was di spersed.
The part i al pressure of
acetic aci dint he atmosphere was set to 6.6 x 10-5 atm.
[ 0125] Exampl e 2
27
CA 03174962 2022- 10- 6
The car boxyl i c aci d- cont ai ni ng ni ckel powder as the aceti c
acid-adsorbed ni ckel powder was obtai ned i n the same manner as i n
Example 1 except that the partial pressure of the acetic acid i n
the atmosphere at the ti me of di spersi ng the ni ckel powder i n the
atmosphere contai ni ng the aceti c acid as the carboxyl i c aci d was
changed to 6. 6 x 10-6 atm.
[ 0126] Exampl e 3
The carboxyl i c aci d-contai ni ng ni ckel powder was obtai ned i n
the same manner as i n Exampl e 1 except that a propi oni c aci d was
used i nstead of the aceti c aci d and the condi ti ons for di spersi ng
the ni ckel powder i n the atmosphere contai ni ng the carboxyl i c aci d
were changed as shown i n Tabl e 2.
[ 0127] Exampl e 4
Fi rst, a powder of ni ckel acetate t et rahydrat e was prepared.
The powder of the ni ckel acetate tetrahydrate was sprayed and
heated to 1500 C i n a gas phase, thereby obtai ni ng the ni ckel
powder di spersed i n the gas phase. The temperature of the gas phase
was adj usted to 300 C i n a state where the ni ckel powder was
di spersed i n the gas phase.
A treatment was performed for 10
seconds by suppl yi ng the aceti c aci d as the carboxyl i c aci d i nto
the gas phase i n whi ch the ni ckel powder i s di spersed. Thereby, the
carboxyl i c aci d- contai ni ng ni ckel powder whi ch was the aceti c aci d-
adsorbed ni ckel powder was obtai ned. The aceti c aci d with a purity
close to 100% (speci al grade 99. 7+% manufactured by Fuj ifilm Wako
Pure Chemi cal Corporati on) was used.
The part i al pressure of the
acetic aci d in the gas phase at the ti me of perf ormi ng the
treatment with the aceti c aci d as the carboxyl i c aci d was set to
6.6 x 10-5 atm.
The vol ume- based cumul at i ve 50% part i cl e di ameter
D50 measured by col I ecti ng the ni ckel powder before suppl yi ng the
acetic acid as the carboxylic acid was 0.31 pm.
[ 0128] Exampl e 5
The carboxyl i c aci d- contai ni ng ni ckel powder whi ch was the
acetic acid-adsorbed ni ckel powder was obtai ned in the same manner
as i n Exampl e 4 except that the temperature of the gas phase at the
ti me of suppl yi ng the carboxyl i c aci d was changed to 500 C and the
28
CA 03174962 2022- 10-6
partial pressure of the aceti c acid in the gas phase at the ti me of
perf or mi ng the treatment with the aceti c acid as the carboxyl i c
acid was changed to 1.3 x 10-5 atm.
[ 0129] Exampl e 6
The carboxyl i c aci d- contai ni ng ni ckel powder which was the
acetic acid-adsorbed ni ckel powder was obtai ned in the same manner
as i n Exampl e 5 except that the part i al pressure of the aceti c aci d
i n the gas phase at the ti me of perf ormi ng the treatment with the
acetic aci d as the carboxyl i c aci d was changed to 6.6 x 10-5 atm.
[ 0130] Comparative Example 1
As a powder of Comparative Exampl e 1, the ni ckel powder used
as
the raw mat en i al powder i n Exampl e 1 was used without the
treatment with the carboxyl i c aci d. Namely, the powder accor di ng to
this Comparative Exampl e was the ni ckel powder which was not
treated with the carboxyl i c aci d.
[ 0131] Comparative Example 2
First, a ni ckel powder having a volume-based cumulative 50%
part i cl e di ameter 050 of 0.31 pm was prepared.
The ni ckel powder was di spersed i n an atmosphere contai ni ng
an ethanol as an al cohol for 10 seconds, thereby obtai ni ng an
alcohol-adsorbed ni ckel powder as an alcohol-treated powder.
The
temperature of the atmosphere contai ni ng the al cohol was adj usted
to 25 C when the ni ckel powder was dispersed. The partial pressure
of the al cohol i n the atmosphere was set to 9. 6 x 10-6 atm.
[ 0132] Comparative Example 3
The al cohol -treated powder whi ch was the treated powder of
the
or gani c compound was produced i n the same manner as i n
Comparative Exampl e 2 except that an i sopropanol was used i nstead
of
the ethanol as the al cohol and the part i al pressure of the
al cohol i n the atmosphere at the time of perf ormi ng the treatment
with the al cohol was set to 8.8 x 10-6 atm.
[ 0133] Comparative Example 4
29
CA 03174962 2022- 10-6
First, a ni ckel powder having a volume-based cumulative 50%
parti cl e di ameter D50 of 0.31 pm was prepared.
The ni ckel powder was pl aced i n an atmosphere contai ni ng an
acetic aci d as a carboxyl i c acid, thereby obtai ni ng a carboxyl i c
aci d- cont ai ni ng ni ckel powder whi ch was an acetic acid-adsorbed
ni ckel powder. The aceti c aci d with a purity close to 100% (special
grade 99. 7+% manufactured by Fuj i film VVako
Pure Chemi cal
Cor por at i on) was used. The treatment ti me with the aceti c aci d was
set to 30 mi nut es.
Further, the treatment temperature at the ti me
of perf ormi ng the treatment with the aceti c aci d was set to 50 C.
Furthermore, the parti al
pressure of the aceti c acid in the
atmosphere at the ti me of perf ormi ng the treatment with the aceti c
aci d was set to 1. 0 X 10-1 atm.
[ 0134] Comparative Exampl es 5 and 6
The car boxyl i c aci d- cont ai ni ng ni ckel powder as the aceti c
acid-adsorbed ni ckel powder was obtai ned i n the same manner as i n
Exampl e 1 except that the condi ti ons for di spersi ng the ni ckel
powder i n the atmosphere contai ni ng the acetic aci d as the
carboxyl i c aci d was changed as shown i n Tabl e 2.
[ 0135] Comparative Example 7
The carboxyl i c aci d-contai ni ng ni ckel powder was obtai ned i n
the same manner as i n Comparati ve Exampl e 4 except that a propi oni c
acid was used as the carboxyl i c aci d i nstead of the aceti c aci d,
the treatment ti me with the carboxyl i c aci d was set to 60 mi flutes,
the treatment temperature at the ti me of perf ormi ng the treatment
with the carboxyl i c aci d was set to 120 C, and the parti al pressure
of the carboxyl i c aci d in the atmosphere at the ti me of perf ormi ng
the treatment with the carboxyl i c aci d was set to 5. 0 X 10-1 atm.
[ 0136] Table 2 was
prepared to show the manufacturing
condi ti ons of the powder of each of the above Exampl es and
Comparative Exampl es.
I n addi ti on to the manufacturi ng condi ti ons,
Tabl e 2 was prepared to show a temperature of a peak top of a peak
i n a mass chromatogram of a mol ecul ar i on (mol ecul ar i on of aceti c
aci d: nu/z=60, mol ecul ar i on of propi oni c aci d: m/z=74) of the
carboxyl i c aci d, where the peak was detected when a temperature was
CA 03174962 2022- 10-6
rai sed from 38 C to 600 C at a heat i ng rate of 20 C/mi n in a hel i um
atmosphere which was an inert atmosphere by using the TG-MS for
each powder.
Tabl e 2 was al so prepared to show a content of the
carboxyl i c aci d per 1 m2 of the surf ace area of the ni ckel part i cl e
const i t ut i ng the obt ai ned powder.
I n this regard, El ( El ect r on
I oni zati on) method was used as an i oni zati on met hod for the MS.
Further, Tabl e 2 was prepared to show presence or absence of the
peak top of the peak i n the mass chromatogram of the mol ecul ar i on
of the carboxyl i c aci d wi thi n the range of (Tbp + 100) C or hi gher
and 600 C or lower, where Tbp [ C] was the boil i ng point of the
carboxyl i c aci d used i n each of the above Exampl es and Comparative
Exampl es 4 to 7. Furthermore, Tabl e 2 was prepared to show presence
or absence of the peak top of the peak i n the mass chromatogram of
the mol ecul ar i on of the carboxyl i c aci d wi t hi n the range of (Tbp -
50) C or hi gher and (Tbp + 50) C or lower.
For the TG-MS, STA2500
Regulus manufactured by NETZSCH was used as the TG- DTA for raising
the temperature of the sample, and j MS- Q1500GC manufactured by j EOL
Ltd. was used as the MS for the mass spectrometri c anal ysi s of
substances vapor i zed by rai si ng the temperature of the sample.
Moreover, the content of the carboxyl i c aci d per 1 m2 of the surf ace
area of the ni ckel part i cl e const i t ut i ng the powder was obt ai ned
using the CS (carbon/Sul fur) anal yzer (EMI A- 320V manufactured by
HORI BA, Ltd.). Speci f i call y, (1) an amount of carbon i n the
ni ckel
powder before the carboxylic acid adsorpti on treatment and (2) an
amount of carbon i n the ni ckel powder after the carboxyl i c aci d
adsorpti on treatment were measured.
Then, a val ue obtai ned by
subt r act i ng ( 1) from ( 2) was def i ned as an amount of car bon
i ncr eased by the carboxyl i c acid adsorpti on treatment, After that,
t hi s val ue, the rat i o of carbon i n the carboxyl i c aci d, and the
sped i f i c surf ace area of the ni ckel powder before the carboxyl i c
acid adsorpti on treatment were used to obtai n the content of the
carboxyl i c aci d per 1 m2 of the surf ace area of the ni ckel part i cl e
consti tuti ng the powder.
I n Table 2, the aceti c aci d was indicated
as "AA", the propi oni c acid was i ndi cat ed as "PA", the ethanol was
i ndi cat ed as "Et OH", and the i sopropanol was i ndi cat ed as "I PA".
[ 0137] [Tabl e 2]
31
CA 03174962 2022- 10-6
C3
2,
o
0
,
.-,J
A
ta
0
m
m
0
m
Y
,
9
0,
Table 2
TG-MS result
Peak in mass Peak in mass
Gas
chromat.gram of chromatogram of
phase
molecular ion of molecular ion of
Adsorpt
temperat
carboxylic acid carhoxylic acid
Treatment Depost
ion
Depoa urn at ime
within the range of within the range
p
t for gas) ar t
amount
it Method for adding deposit the time
(Th,¨nulcc or higher of :Tb, + /oo) c
usinP de ial press
of
Type of
and (Tbp , 50) C or or higher and
posit ore [atm]
deposit
adding lower 600 C or lower
[1.germ'l
deposit
Presence
Presence
lb
Peak top or Peak top
or
s.
Temperatu Absence Temperat
nce of p
re jaC]
of peak ore I'd]
eah top
top
Disperse powder in gas phase of 10
Ex.1 Al 1DC seconds 6.6.10-'
395 Presence 120 Presence 360
carboxylic acid atmosphere
Disperse powder in gas phase of 10
Ex.2 AA 1DC 6.6.10-6
155 Absence - Presence 380
carboxylic acid atmosphere seconds
Disperse powder in gas phase of 10 =
Ex.3 PA 120 1.3.10-'
215 Absence - Presence __ 270
carboxylic acid atmosphere seconds
Supply carboxylic acid gas into
Ex.4 Al gas phase where powder is 300 d E.Ex10-'
275 Absence - Presence 380
secons
UJ dispersed
NJ Supply carboxylic a,id gas into
Ex.5 Al gas phase where powder is 500 1.3x10-'
/73 Absence - Presence 380
dispersed
seconds
Supply carboxylic acid gas into
Ex.6 AA gas phase where powder is 500 E.E.10-'
226 Absence - Presence 360
seconds
dispersed .
Corn
- - - - - -
Ahsence - Absence -
Ex.1
torn Disperse powder in gas phase of 10
Et0H 25 ,r1.0-.
223 Absence - Absence -
Ex.2 alcohol atmosphere seconds
Com Disperse powder in gas phase of 10
IPA 25 6.6.11)
2D7 Absence - Absence -
Ex.3 alcohol atmosphere seconds
Corn Place powder in carboxylic acid 30
AA 1.0x10-1
516 Presence 120 Presence 260
Ex.4 atmosphere minutes
Com Ex5 seconds
Disperse powder in gas phase of 10
Al /00 E.Ex10-4
542 Presence 120 Presence 360
. carboxylic acid atmosphere
Cow Disperse powder in gas phase of 10
AA /DO 3.5.10-'
101 Absence Presence 300
Ex.6 carboxylic acid atmosphere seconds
Cam Place powder in carboxylic acid E0
PA 120 5Ø10-r
633 Presence 140 Presence 270
Ex.7 atmosphere minutes
'Ex" refers to Example.
'Corn Ex" refers to Comparative Example.
[ 0138] PRODUCT! ON OF Fl NE POWDER BY DRY CLASS! Fl CATI ON
The powder of each of the Exampl es and Compar at i ve Exampl es,
that i s, each of the carboxyl i c aci d- cont ai fling ni ckel powder for
the Exampl es and Comparative Exampl es 4 to 7, the ni ckel powder for
Comparative Exampl e 1, and the alcohol-treated
powder for
Comparative Exampl es 2-3 was put into the dry classifier shown in
Fl G. 1 at 10 kg per hour. The supply di spersi on pressure was set to
0.6 MPa. As a resul t, a powder to be cl assi f i ed was obtai ned.
[ 0139]
Next, the powder to be classified was introduced into
the cl assi f i cat i on chamber. Then,
the dry cl assi f i cation was
performed under the condi ti ons that the temperature i nsi de the
cl assi f i er was set to 25 C, the suct i on ai r vol ume was set to 8.5
m3/ mi n, and the suction pressure was set to -35 kPa. As a result, a
f i ne powder was produced.
[ 0140]
Thereafter, the obt ai ned f i ne powder was subj ect ed to
the dry Cl assi f i cat i on i n the same manner as descri bed above.
Namely, the dry cl assi f i cat i on was performed twi ce i n total to
obt ai n a fi nal f i ne powder.
[ 0141] EVALUATI ON
[ 6- 1] Yield
For each of the Exampl es and Comparative Exampl es, the wei ght
of
the powder before the Cl assi f i cat i on and the wei ght of the
powder after the cl assi f i cat i on, i . e. ,
the wei ght of the f i ne
powder obt ai ned by perf ormi ng the cl assi f i cat i on treatment twice
were measured.
After that, the yi el d was cal cul at ed by the
f ol I owl ng equat i on.
Yi el d CVO = (wei ght of powder after Cl assi f i cat i on/wei ght of
powder before cl assi f i cat i on) x 100
[ 0142] [ 6- 21 EVALUATI ON OF PARTI CLE SI ZE DI STRI BUTI ON
For each of the above Exampl es and Comparative Examples,
part i cl e size di st ri but i ons were measured for the ni ckel powder as
the raw mat eri al powder and for the obt ai ned f i ne powder by usi ng
the
I aser di f f r act i on/ scatt eri ng particle size anal yzer LA- 960
33
CA 03174962 2022- 10-6
(manufactured by HORI BA, Lt d. ) .
Based on the results, a val ue at
the vol ume- based cumul at i ve f r act i on 10% ( Dio) [ pm] , a val ue at
the
vol ume- based cumul at i ve f ract i on 50% (D50) [ pm] , and a val ue at the
vol ume- based cumul at i ve f r act i on 90% (D90) [ pm] of the part i cl e
si ze
di st ri but i on were det ermi ned respectively.
[ 0143]
Then, ( D90 - Dio) / D50 was cal cul at ed based on t he val ues
of D10 [ pm] , D50 [ pm] , and D90 [ pm] det ermi ned as descri bed above.
[ 0144] [ 6- 3] EVALUATI ON OF COARSE PARTI CLE COUNT
For each of the above Exampl es and Comparative Exampl es, a
di spersi on I i qui d was prepared by mi xi ng 1 g of the powder after
two times of the cl assi f i cat i on with 20 ml of ethanol
as a
di spersi on medi um, whi ch mi xt ure was treated with an ul t rasoni c
cleaner (W-113 manufactured by Honda El ect roni cs Co., Ltd.) for 1
mi flute, A sampl e for measurement was prepared by sampl i ng 30 pl of
the
prepared di spersi on I i qui d, dr oppi ng the sampl ed di spersi on
I i qui d onto an al umi num sampl e stand, and dryi ng to remove the
di spersi on medi um.
The sampl e obtai ned was observed with the
scanni ng el ectron microscope (SU- 1510 manufactured by Hitachi Hi gh-
Tech Cor por at i on) for 50 f i el ds of vi ew at a magni f i cat i on of
10, 000 times.
The tot al number of coarse part i Cl es, whi ch were
def i ned as those with a part i cl e di amet er 2.0 times or greater than
the D50 of the target fine powder determi ned in [ 6- 2] above, was
count ed.
[ 0145] [ 6- 4] SMOOTHNESS OF COATI NG Fl LM
The powder of each of the Exampl es and Comparat i ve Exampl es
obt ai ned in the above [ 4] , i . e. , 100 parts by wei ght of the powder
before the Cl assi f i cat i on treatment, 3.0 parts by wei ght of an
ethyl cell ul ose resin ( STD100 manufactured by Dow Chemi cal Company)
and 100 parts by wei ght of di hydrot er pi neol acetate were mi xed to
obtain a mixture.
Then, the mixture was mixed at 2000 rpm for 2
mi nut es by a hybr i d mi xer ( ARE- 310 manuf act ur ed by THI NKY) to
obtain a nickel paste.
The obt ai ned nickel paste was cast with a
film t hi ckness of 10 pm, and the surf ace roughness Ra was measured
by using a fine shape measuri ng i nst rument ( ET3000i manufactured by
Kosaka Laboratory Ltd. ).
34
CA 03174962 2022- 10-6
[ 0146] For the f i ne powder of each of t he Exampl es and
Compar at i ve Exampl es obt ai ned i n t he above [ 5] , a past e was
prepared, a coati ng film was formed by usi ng the paste and a
surf ace roughness was measured i n the same manner as descri bed
above.
[ 0147] These results are coil ecti vel y shown i n Tabl e 3.
Further, as for the f i ne powder obtai ned i n each of the above
Exampl es, the number of part i cl es havi ng a part i cl e di amet er of 3.0
times or more of the volume-based cumulative 50% particle diameter
D50 of each fine powder was determi ned by the method shown in [ 6- 3].
As a result, such a part i cl e was not contai ned therei n for any of
the Exampl es.
[ 0148] [Tabl e 3]
CA 03174962 2022- 10-6
C7
>
0
0
,
-4
A.
.o
o
m
m
o
m
Y
,
9
o, Sable 3
Classification
Smoothness of coating film
Number of
YHeld TI:c n. n., (11..,- ,CRTSR
Surface roughnass Surface roughness
(using powder before classification)
(using powder after classification)
[1.] [Um] [pm] Ipm] Dln)/DFn particles
Lnmj Lnmi
[Poe]
Example 1 92.2 0.19 0.25 3.41 0.79 23 40.6
30.9
Example 2 93.3 0_99 0.29 0_41 2.74 20 62.5
85.1
'
Example 3 61.1 0.19 0.28 0.41 0.79 19 53.3
50.5
Example 4 63.8 0.19 0.28 0.41 0.73 18 55.2
51.3
Example 5 83.5 0.15 0.29 5.41 0.75 18 60.7
57.8
Example 0 92.0 0.19 0.28 0_41 0.79 17 57.2
53.6
Comparative
52.5 0.18 0.27 0.42 0.99 82 90.2
87.4
Example 1
Comparative
64.7 0.19 0.30 0.45 0.87 55 80.5
75.6
Example 2
comparative
65.4 0.19 0.30 0.45 0.87 5E 77.1
72.1
Example 2
Comparative
62.1 0.15 0.28 0.41 0.79 23 109.2
103.1
Example 4
comparative
61.9 0.19 0.28 0.41 0.79 23 113.9
105.1
UJ Example 5
01 Comparative
74.4 0.19 0.29 5.42 3.82 42 71.1
27.9
Example 8
Comparative
01.0 0.19 0.29 0_42 0.82 20 125.0
118.1
Example 7
[ 0149]
As is apparent from Table 3, each of the above Exampl es
suitably produced the metal f i ne powder havi ng the D50 i n the range
of from 0.01 pm to 5.0 pm and an extremely small number coarse
part i cl es with a hi gh yi el d.
From thi s, it can be sai d that the
carboxyl i c aci d- cont ai ni ng ni ckel powder of each of the Exampl es i s
excel I ent i n the di spersi bi I i ty i n the gas phase.
I n addi ti on, i n
each of the Exampl es, the surf ace roughness of the coati ng film
formed usi ng the paste i s small and the smoothness thereof i s hi gh.
From this,
it can be said that the carboxyl i c acid-containing
ni ckel
powder of each of the Exampl es i s excel I ent i n the
di spersi bi I i ty i n the paste.
I NDUSTRI AL APPLI CABI LI TY
[ 0150] The carboxyl i c acid-containing ni ckel
powder of the
present i nventi on cont ai ns a pl ural i ty of ni ckel part i cl es and has
a carboxyl i c aci d on a surface of each of the ni ckel parti cl es,
wherei n by using a TG-MS, when a temperature is rai sed from 38 C to
600 C at a heat i ng rate of 20 C/mi n i n an i nert atmosphere, a peak
i s detected i n a mass chromatogram of a mol ecul ar i on of the
carboxyl i c aci d and wherei n when a boil i ng poi nt of the carboxyl i c
acid is Tbp [ C], a peak top of the peak exi sts wi t hi n a range of
(Tbp + 100) C or hi gher and 600 C or I ower, and wherei n a content of
the
carboxyl i c aci d per 1 m2 of a surf ace area of the ni ckel
part i cl e consti t uti ng the carboxyl i c aci d- contai ni ng ni ckel
powder
i s 155 lig or more and 450 pg or I ess.
Thus, it is possi bl e to
provide the carboxyl i c aci d- cont ai ni ng ni ckel powder havi ng hi gh
di spersi bi I i ty i n a gas phase and hi gh di spersi bi I i ty i n a paste
when used for f ormi ng the paste by mi xi ng with an organi c sol vent
and the I i ke.
The met hod for pr oduci ng the carboxyl i c aci d-
cont ai ni ng ni ckel powder accor di ng to the present i nventi on is a
met hod for producing the carboxyl i c aci d- contai ni ng ni ckel powder
of the present i nventi on. The method i ncl udes a step of bri ngi ng a
carboxyl i c aci d in a gaseous state i nto contact with a ni ckel
powder di spersed i n a gas phase.
Thus, it is possi bl e to provi de
the
method for produci ng the carboxyl i c aci d- cont ai fling ni ckel
powder havi ng the hi gh di spersi bi Ii ty in the gas phase and the hi gh
di spersi bi I i ty i n the paste when used for f ormi ng the paste by
37
CA 03174962 2022- 10-6
mi xi ng with an or gani c sol vent and the I i ke.
Therefore, the
car boxyl i c aci d- cont ai ni ng ni ckel powder of t he present i nvent i on
and the met hod for producing the carboxyl i c aci d- cont ai ni ng nickel
powder have i ndust ri al avail abi I i ty.
EXPLANATION OF REFERENCE NUMERALS
[ 0151] 1: CLASSI Fl ER
3: CASI NG
4: I NTRODUCTI ON PORT
5: Al R NOZZLE
6: GUI DE VANE
7: Fl NE POWDER DI SCHARGE PORT
8: COARSE POWDER DI SCHARGE PORT
10: CLASSI Fl CATI ON CHAMBER (CLASSI Fl CATI ON ZONE)
11: DI SPERSI ON ZONE
38
CA 03174962 2022- 10-6
