Note: Descriptions are shown in the official language in which they were submitted.
20~3~7
WArER SOLUBLE SALT PRECOATS FOR ~IRE DRA~ING
BACK~ROUND OF THE I~VENTION
.
I. Field of the InYentlon
Thls inventlon relates to modifled water so1uble salt
precoats for use ~n the cold drawlng of steel w~re.
2. Backg ound o~ the InYentlon
5~ater soluble salt codt~ngs are often applied to steel
w~re 1n the for~ of a~ueous solutions pr10r to drawlng. The
solution-coated wire ls dried and the result1ng salt coated wlre
1s then drawn through conventlonal reduc~ng dles uslng dry soap
lubricants - a process well-known to this art. The water soluble
IOsalt coating acts as a lubrlcant carrler, pulllng the dry soap box
lubricant ~nto the dles, thus provldlng lubrlcat10n. These drled-
in-place, water soluble salt coatings have proven to be superior
to other convent10nal coatings such as llme or borax coatings
because of their lmproved abillty to carry lubrlcank lnto the
15dles, A typlcal soluble salt composlt~on used for the coatlng of
steel (usually stalnless steel) wire conta~ns both sodlurn sulfate
and borax. Such soluble salt composltions prov~de coattngs wlth
excellent crystall~ne structure, resultln~ ln good soap lubr~cant
plck up when the coated wlre ls passed through a soap box, and
~0therefore good drawablllty. ~owever, such salt coatlngs are prone
2~ 377
to excesslve molsture absorptlon upon exposure to amblent alr,
partlcularly when exposed to alr haY1ng hlgh humldlty. Such
mols~ure absorptlon serlously lnterferes wlth, or even prevents,
the draw~ng of the coated wlre. 5n the other hand, soluble salt
coatlngs whlch prov~de low rnolsture absorptlon orovlde 11ttle or
oo crystalllne structure (~.e. amorphous or glaze type coatings)
and arP slgnlflcantly infer~or ln both lubrlcant plck-up and drawa
blllty. Thls Hobson's cholce problem has not prevlously been
solved.
STA~EMENi OF TI~E INYENTION
Other than ln the operatlng examples, or where otherw~se
lndicated, all numbers expresslng quantlt~es of lngre~ents or
reactlon conditions used herein are to be understood as modif~ed
1n all lnstances by the ter~ "aboutn.
Compositions for coat~ng steel wire have now been dlscovered
which prov~de uniform coatings wlth good crystalllne structure,
soap pick-up, and drawability, while at the same time low moisture
absorptlon even dur~ng humid days, t.e. low hygroscoplclty.
The compositions of the lnvent~on, which are in the for~ of
dry m~xtures prior to d11utlon with water for use, conta~n the
~ollow~ng components:
A. from 50 to 99.99, preferably from 70 to 89.9% by we~ght
K2SO4;
B. from O to 49099, preferably from 10 to 29.9~ by welght
K2B407 and/or KB02; and
C. fro~ 0.01 to 5, preferably from 0.1 to 1.0% by we~ght of
an ammonium or potasslum soap,
wherein up to 50% by welght, and preferably no more than 10X
by we~ght, of the total potasslum lons and arnmon~um lons pre-
sent ln A., B. and C, can be replaced wlth sodlum lons. More
preferably, substantlally none o~ the potasslum and ammon~um
are replaced wlth sodlum lons, slllce the more sod1um ~ons
present, the greater the hygroscoplclty. When sodlum 10ns are
present, they can be present ln one or more o~ components A~,
-2--
2 ~ 7
B. and C., e.g. component C. can be part~ally or entlrely a
sodlum soap. Al 50, component A. andlor B. can be a sodlum
or a potasslum salt, or a ml~ture of such salts, provlded the
llmitat10n on total quantlty of sod~ùm lon ~5 rr~lntalned.
S The fdct that the above compos~tlons prov~de Qood crystalll
-nity on steel wlre ls completely unexpe~ted, s1nce the above
cotnpos~t~cns without component C. glve non-unlform csat1ngs on
steel wlre wh~ch are not useful as such s~nce both soap p1ck-up
and drawabll~ty are unsatisfactory. In some unknown manner, the
I0 presence of t~le soap prov1des an at least part1ally crystalllne
uniform coatinq when the composition ln aqueous solut~on 1s
applled to the steel w1re wh1ch is then dried or allowed to dry.
The K2SO~ used as c~mponent A. can be chemlcally pure or of a
technlcal grade; the latter be1ng preferred due to cost con~
sider~tions.
The K2B407 used as component B. can also be chemically pure
or a techn~cal grade, and 1s generally available and used here1n
as the tetrahydrate (K2B407-4H20). Slmilarly, the KB02, whlch can
be used alone as component B, or ~n a mlxture wlth K2B407 1n any
proport10ns, can be chemlcally pure or a techn~cal grade.
The am~on1um or potass1um soap ~s one or more ammon~um andlor
potass1um salts of a C12-C22 fatty ~c~d or m~xture of two or more
such C12-C2~ fatty ac1ds. The fatty ac1ds are general1y saturated
and unbranched, wlth ammon1um or potass1um stearate belng pre-
ferred for use here1nl although mono- or dl-olefln~cally unsa-
turated C12-C22 fatty ac1ds can also be employed, e~ther alone or
1n m1xtures wlth each other andlor wlth saturated fatty acldsO For
example, amrnon~um and potass~um soaps der1ved frcm the fatty acld
mlxtures obtalned by the saponificatlon of tallow oil or coconut
oil, or a mlxture thereof, can advantageously be employed as com-
porlent C~ Also, ar~non1um or potass~um salts of branched or
cycloal~phatlc-conta~nlng Cl2-C22 fatty aclds can also be employed
here1n, elthcr alone or ln m~xtures wlth unbranched fatty acld
salts. A~so, am~onlum or potass~m ros~n ac1ds, e.g. ab1etlc acld,
can also be employed as c~nponent C~
The w1res coated w~th the coatlng composltlons o~ the lnven-
t~on are generally steel wlres, and usually stalnless steel w1res.
2~37~
However, other w1re substrates can also be coate~ wlth the present
coatlng composltlons such as mlld steel, t1tanlum, vanadlum,
tungsten, alumlnum, copper, nlckel, zlrconlum, etc., and alloys
thereof.
S The cGatlnys are dpplled by contactlng the w1res wlth an
aqueous solutlon o~ the c~nposltlon of the Invent10n, and allowlng
the resulting wet coatlng to dry ln place, elther wlth or w1thout
the apptication of heat. ~he aqueous solutlons generally conta1n
from 75 to 400 g/l of the c~mpos1t~on in water, preferably from
l50 to 250 ~Jl.
The wlre ls contacted with the solut~on by any conYenlent
technique, elther batch or a continuous strand, and allowlng the
resultlng wet-coated w1re to air dry before coll~ng ~or storage,
shlpping, or use. The coated wlre ls then passed through conven-
t~onal cold reduction equipment using a soap box (e.g. contain~ng
a conventlonal dry soap lubrlcant). The coat1ng on the w~re
functlons as a carrier to carry the dry soap lubrlcant lnto the
d~e.
The steps employed in the treatment of wlre accord~ng to the
invention lnclude the follow~ng:
1. Cleanlng the w~re - cleaning composltlons are well~known
ln the art and dc not comprlse part of the present
Invention.
2. Rlnslng wlth water.
3. Pickllng - here atso, pickllng composltlons are well-
known and the selectlon of a plckllng composltlon Ic not
part of the lnventlon.
4. Rlnslng wlth water.
5. Applying the coatlng composit10n of the 1nventlon as
descrlbed above.
6. Drylng the wlre as descr~bed above to produce the coated
wlre o~ the 1nventlon.
The coated wlre can then be drawn, also as descrlbed above,
The water used ln preparlng the aqueou5 solutlons o~ the
lnventlon lS pre~erably dlstllled or delonlzed water, but tap
water can also be used provlded lt ls not overly hard and has a
low dlssolved sodlum salts contentu
, -4-
` 2~3~
The lnventlon wlll be lllustrated but not llmlted by the
follow~ng examp1es.
EXA~PLES
EXAMPLL 1
The follow1ng 3queous cornposltlons were tested ~or the~r
morphology and hygroscopic~ty, when coated on stalnless steel
panels. Stalnless steel panels were coated wlth each of the
follow~ng composltions by ~rmerslng the panels ln the aqueous com-
posltion, removlng the ,oanels ,rom the ~ueous c~mposlt~on, and
allow~ng them to fldsh (alr) dry.
a) 187.2 Q of a mixture of 75 wgt X Na2S04 and 25 wgt X
sodlum tetraborate 10H20 per liter o~ delonlzed water.
Use temperature l90F.
b) 187.2 g of a m~xture of 75 wgt % K2S04 and 25 wgt X
~2B~07 4HzO per llter of deionized water.
Use temperature 190F.
c) to an aqueous solut~on prepared as ln a) was added 5 gll
of s~dlum stearate.
Use temperature l90 F~
d) to an aqueous solution prepared as ln b) was added 5 9/1
of a~mon1um stearate.
Use t~mperature 190 F.
The sectlons of sta~nless steel panel coated w1th the above
compositlons were then tested for hygroscopiclty and morphology.
The test results are set forth ln Table I be10w. In Table I, RH
relatlve hum~d~ty.
TABLE I
e}9C'~55EL~.LC~
Coat1ng
Bath ~0-95X RH/Amblent Alr
~tlon 90 mln. _24 hr. MorPh
a) 16.5X 107.0X Crystalllne
b) 5,1X 2.7X Amorphous glaze
c) lG. }% - Crystal 1 lnelsome glaze
d) 7.5X_ _ _ 3 4X _ _ _Cr,xstalllne/some~_ze
-5-
2~Q~3~7
* Average percent molsture ln t~,e coatlng. Molsture p1ck-up
measure~ by welght d~fferentlal o~ the uncoated panel and the
coated panel before and after alr exposure.
As can be seen from Table I, the compositlon of the lnven-
tlon, composlt~on d), produced a coatlng wlth good crystall~n~ty,
and low hygroscoplcity.
EXAMPLE 2
Thls example shows the effect of reldtlve ratlos of sodium
and potassium ions on the hygrosc3picity of the water soluble salt
coat~ngs. In th1s exarnple, stalnless steel panels were coated ln
accordance with Example 1 using the follow1ng compositlons, at a
concentratlon of 187.2 g/l ln delonlzed water, set forth ln Table
~I be~ow together w~th test results. In Table Il, M = molarlty or
gm-moles/liter of solution and RH = relatlve humidlty.
TABLE II
.
Coatlng Bath Composltlon: Hygroscoplclty:
Na,M K,M S04,~B407,MStearate, M90-95X RH/24 hrs.
e) 2.23 - 0.99 0.123 - 107.0X
f) 1.98 0.246 0.99 0.123 - 90.2%
9~ 0.246 1.98 0.99 0.123 - 10.6~
h) - 2,23 0.99 0.123 - 2.7%
~) - 2.23 0.99 0.123 0.016 3.4X
. _ _ _ _ . _ _ _ _ _ . . ~ _ _ _ . _ _ _ _ _ .
EXAMPLE 3
Thls example shows the relatlve hygroscop~c1ty of l~me
coatlngs compared to the coatlng from a known sodlum basecl salt
composltlon and a low sodlum salt composltlon of the lnventlon.
rhe coatlngs were produced on samples of the stalnless steel w~re
used ln Example 1 accordlng to the procedure of Example 1 trom the
follow1ng aqueous composltlons:
~) 187.2 9 of a mixture of 75 wgt X Na2S04 and ?5 wgt ~ sodlum
tetraborate~lOH20 per 11ter of delonlzed water.
Use temperature 190 F.
--6--
2~Q~37~
k) 1a~.2 9 o~ a mlxture of 79 wgt X K2S04, 20 wgt % sodlum tetr~-
borate lOH20, and 1 mole X or ammonlum stearate per llter o~
delonlzed water.
Use te~perature 1gO F.
l) 3% by welght of lllne ln de~on1zea water.
Use temper~ture 190 F.
m) 6% by welght of llme 1n delon~zed water.
Use temperature 190~ F.
The results are shown ln Table III be1Ow.
TA~LE I I I
Coat1ng Bath
~p_slt10n% molsture plck-up, 80-9OX RH, 24 hrs
J~ 28.3X
k) 3.0X
1) ~7.6~
_m) - 18.4X
~ . . .
As can be seen from Table III above, c~mposltlon k) ln
accordance wlth the lnvent10n has slgnlflcantly reduced hygrosco-
plctty compared to l~me coatlngs l) and m).
EXAMPLE 4
Ten dlfferent coatlng bath composltlons were evaluated for
~5 molsture plck up, morpholo~y, coatlng un1fonm1ty, and crystals per
lnch on stalnless steel panels.
The stalnless steel panels were coated wlth the coatlng com-
posltlons and coatlny baths set forth ln Table IY, accordlng to
the process glven ln Example 1, except that the wet-coated panels
were dr~ed us~ng a I0 mlnute bake at 250F. Molsture plck-up was
determlned ln a chamber whlch allowed constant temperature and
humldity of 80F and 92X respectlvely. A Surtron~c 3 sur~ace
prophylometer was used to determlne the number o~ crystals per
lnch o~ coatlng. Coatlng characterlzatlon and coatlng appearance
3S were determlned by vlsual observatlon.
~7-
2~3~7
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O ~ O ~ ~ ~~ C ~ ~ ~ ~ ~ ~ g
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.
20~377
In ~able IV, coatlng composltlons F, G, dnd J ara com-
po51tlon5 ln accordance wlth the lnYentlon, whlle coTposltlons A9
B, C, ~, E, H and I are comparlson composltlons. As can be seen
fr~m Table IV, conpos~t~ons F, G and J prodused unl~orm coatlngs
whlle exhlbltlng low mo1sture plck up. The only cDmparlson com-
posltlon that produced a unlform coat1ng waj c~mposltlon B, whlch
however exhl~lted an unacceptably h1gh ~olstur~ plck up. In fact,
composltions A, B, and C all exhlbited un3cceptably hlgh molsture
plck up, and hence poor wlre drawablllty propertles 1n humld con-
ditlons. Coat~ng cornpos1tlon E contalns potasslum sulfate andsodium stearate soap 1n accordance wlth the composltlons of the
lnven~lon, except that the sodlum stearate soap 15 present in too
hlgh a quantlty, resultlng ln a non-unlform, r~stly glaze coatlng,
havlng unacceptable wlre drawlng propertles. Coatlng composltlons
D, H, and I whlch are potass1um salt co~posltlons ln accordance
with the lnYention except that no soap ls present thereln, all
produced unacceptable non-unifùrm coatings and hence unaccep-
tability intonslstent w1re drawing characterlstlcs. In comp~rlng
coating compositions F, G and J of the lnventlon, c~mposltlon J
contaln1ng an alkall metal tet,aborate produced the most
crystalline coatlng. Hence, the presence of a tetraborate ln the
coat~ng conposltlons of the lnventlon, ~hlle optlonal, ls
nonetheless highly preferred.
