Note: Descriptions are shown in the official language in which they were submitted.
~%~
^ 1 -
SILANE DISPERSING AGENT
FOR MAGNETIC MEDIA
BACKGROUND OF THE INVENTION
This invention relates to a novel
sil~ne-contalning dispersing agent in~ended for use
in the dispersion of ferromagnetic particles
employed ~n magne~ic coating. More particularly,
this in~ent~on relates to novel compositions
contalning silylated copolyethers or isocyanato
silanes wi~h phosphate esters as the
silane-containing dispersing agent.
PRIOR ART
Audio and video tape and other
informat~on-storing magnetlc media, can be prepsred
by coat~ng MylarTM or some other non-magnetic
substrate with a solvent-based magnetic coating
cont~ining ~ine ~errom~ tic p~rticles dispe~sed in
a suitable polymeric binder. In conventional
practice, the acicular (needlelike) ferromsgnet1c
particles are orien~ed ~n a magnetlc field and the
solvent is evaporated.
The current trend in the electronics
industry is toward higher information density which
can be achieved with suitable dopants (often cobalt)
and by the use o~ progressively ~-maller
ferromagnetic partlcles of h~gh coerclve strength.
These ~actors increase dispers~on viscosity
enormously. Consequently, effectlve dispersing
agents are needed to sch~eve the high partlcle
loading densi~y required.
Prlor art teachin8 dlsperslng agent~ for
magnetlc media da~es back 15-20 years. U.S. Pa~ent
D-14679
2 -
3,144,352 describes the use of lecithin British
Patent 1,080,614 describes the use of oleic acid
lubricant ~nd monobutyl phosphate dispersant. ~er.
Offen. 2,543,962 teaches ~he use of aminosilanes for
improved dispersibility and abrasion resistance.
U.S. Patent 4,076,890 teaches a range of
organofunctional silanes as dispersing agen~s
(including alkyl, amino, mercapto, epoxy, vinyl,
chloro~ in magnetic media for abrasion resistance
and reduced drop-out.
Organo$unctlonal silanes have likewise been
reported as improving the squareness ratio in
magnetic coatings. Japanese Kokai 81 49 767 and CA
g5-995~6.
Phosphate dispersants are widely reported
in the literature. Sodium metaphosphate (CA
86-19g032). Potassium dihydrogen phosphate
(~apanese Kokai 79,143,894). Polyethylene-
polypropylene glycol monoether phosphates (J~p~nese
Kokai 82,205,461). Dioctylphosphate (European
Patent Application 48456). Phosphoric acid alkyl
ester (U.S. Patent No. 4,244,987). Lecithin (U.S.
Patent Nos. 3,144,352 and 4,196,258).
Combinations of aminosil~nes with
surfactant are disclosed in Japanese Kokai
58,1559517 and U.S. Patent No. 4,244,987.
In broad strokes, the prior art mentions
the use of ~ range of organofunctional silanes for
various benefits in magnetic coating. Notably
absent, however, ~re re~erences to polyether silanes
or isocyanato ~ilanes. Cited dlspersing agents ~lso
include a rangP o~ candidates, chiefly the
phosphates.
D-14679
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The frag~le needle-llke ferromagnetlc
particles have an unusually high propensity to form
strong aggregates primarily because of magnetic
attraction between particles. To a lesser degree,
part~cle asymmetry, surface area, surface roughness
and sorbed species (air, water) slso favor
agglomerat~on. When an inappropriate dispersing
agent is used, mechanics~ d~spersion can fracture
the ferromagnet~c particle causing a performance
loss. This is of particular concern with fine
ferromagnet~c particles designed for higher
information densi~y. Thus an effectlve dispersing
agent, such as presently set forth, performs an
important unction.
This present inventlon ~s novel in th~t it
provides the use of a combination of a polyether
silane or isocyanato silane and an organophosphate
ester as an effective dispersing agent for use in
magnetic coatings. Unexpected benefits in the
reduction of viscoslty is an impor~ant aspect of
this invention not previously descrlbed in the prior
art.
SUMMARY OF THE INVENTION
The novel composition of a silylated
copolyether or ~n isocyanato silane with Rn
orgsnophosphate este~ outperformed "state of the
art" dispersing agents. The novel dlspersant of the
present invention w~s found to be ef~ectlve when
integrally added or pretreated on the ferromagnet~c
particle. Because dispersion viscosity is
effectively reduced, higher pigment lo~dings without
D-14679
the loss of ~ilm integrity; reduced grinding times;
reduced sur~actant demand; magnetic co~tings with
improYed tensile strength, squareness (ratio of
remnant magne~ic flux density to satura~ion magnetic
flux density) magnetic proper~ies, surface
appearance and less migration of dispersing agent to
the surface of the magnetic coating are expected as
concom~tant benefits.
DETAILIED DESCRIPTION~ OF THE INVENTIO~
In accordance with the ins~ant invention
there is provided a novel dispersing composition
useful in the dispersion of ferromagnetic partlcles
in the manufacture of magnetic coatings. This
dispersing composition comprises a silylated
copolyether or ~n isocyana~o silan~ with a phosphate
ester.
The s~lylated copolyether employed as a
component in the dispersing agent of the present
invention is of th~ general formula:
R2 ~4
[~30(CmH2m-cHo)x~cH2-cH~o)y CWH2W~ 2 Si [ ~ 4-(2 a)
~here Rl ls indivldually a hydrogen atom, an alkyl
group having from 1 to 12 carbon atoms, an alkoxy
slkyl group having from 2 to 12 carbon atoms, or sn
acyl group having from 6 to 12 carbon a~oms; R2is
individually a hydrogen atom, sn alkyl group h~ving
from 1 to 18 carbon atoms or ~n aryl group having
D-14679
~2~
-- 5
from 6 to 18 carbon atoms; R3 is indlvldually a
hydrogen atom, an alkyl group having from 1 to 12
carbon atoms, an aryl group having from 6 to 18
carbon atoms or an aryl alkyl group having from 7 to
18 carbon atoms; R is individually an alkyl group
having l to 4 carbon atoms; the sum of x + y has a
value of from 2 to 100, preferably 10 to 60; z has a
vAlue o$ 1 ~ ? or 3 and preferably is equal to 1; w
has a value 0 to 6, preferably 3; m has a value of
1, 2 or 3; and a has a value of O or 1.
Exemplary silylated copolyethers which are
useful in practicing the present invention include,
but are not limited to,
C,H3
CH30(CH2-C-0)27(CH2-cH2-0)24 C3H6si(0CH3)3
CH3
C4HgO(CH2-C~0)5C3H6Si(OcH3)3
H
C~3
C4HgO(CH2-C-O~gC3H6Si(OCH3)3
H
CH30(CH2-CH2O312~3H6S~(OcH3)3
D-14679
C4H9o~cH2-cH25))l2c3~l6si(ocH3)3
CH30(CH2-CH20) 1oC3H6Si (OCH3 )3
,CH3
CH30(CH2-C-0)2C3H6sl~OcH3)3
H
CH3
~-O( CH2 -C -O ) 4 ( CH2 -CH20 ) 4C3H6S i ( OC2Hs ) 3 and
H
C9Hlg-~-o(cH2-cH2-o)lo-c3H6si(ocH2-cH2ocH3)3
C, H3 / CH3
CH -O(CH2-C-0)2~CH2-CH20)24C3H6Si(OcH3)2
3 H
:
CH3
CH C(O)O(CH2-C-0)5C3H~, Si(OCH3)3
D-14679
,
~2~
C~3 C2~Hs
~H o~cH~-c-o)4o(cH~-cH2o)24c3H6si~ocH3~2
Generally, the s~lyla~ed copolyethers are
commercially ava~lable or they may be prepared by
reacting a hydroxyl end capped polyether wlth allyl
chloride followed by the hydrosllylatlon of the
adduct, l.e., as ~aught in U.S. 2,868,~24 and U.S.
2,846,458.
The isocyanRto sllane employed ~s an
alternat1ve to the sllylated copolyether component
in the d1spersing agent is of the general formula
II.
~6
OCN-R -Si-~OR )3-b
where R6 is indivlduslly an alkyl group
having 1 to 4 carbon a~oms; R7 is lndividually a
hydrogen atom, an alkyl group having from 1 ~o 12
carbon atoms, an alkoxy alkyl group having from 2 to
12 carbon a~oms or an acyl group hav~ng from 6 to 12
carbon Rtoms; b is O, 1, 2 or 3; and R is an
alkylene, arylene or aralkylene grou~ havlng from 1
to 18 carbon atoms or a group o the ~ormula:
D-14679
.
-- 8
H O
~ N - C - NH - C3H6-
CH3 ~
OCN
Exemplary isocyanato silanes include but,
are not limi~ed to,
C,H3
OCN -:C3H~ - Si - (OC~3)2
OCN - C2H6 - Si - ~OCH3)3
l_ O
OCN ~ ~ N C - HN - C3H6 - Si (OCH3)
OCN ~ (C3H6) Si (OCH3)3
o, m, p isomer
OCN - C3H6 - Si (OC2Hs)3
The isocyanato silanes are commercially
available or they may be prepared by forming the
carbamate adduct of an alkylchloroformate with an
aminoalkyltrialkoxy silane and cracking the
carbamate to form the isocyanato silane~and
alkanol. See for instance U.S. Patent 3,607,901.
D-14679
~L2~
_ 9
The phosphate ester employed as a second
component in the dispersing agent of the present
invention is of the general formula:
III.
R9 0
[R8((:~CH2-C )c(oc~2-cH2)do~e P [OA~v
where R is a hydrogen atom or an alkyl
group containlng from 1 to 1~ carbon atoms; R is
a hydrogen atom, an alkyl group containing from 1 to
4 carbon atom, an aryl group containing from 6 to 18
carbon atoms; or an alkylaryl group containing from
7 to 17 carbon atoms; the sum of c ~ d has a ~alue
of from 2 to 100 and preferably c is at least 1; e
has a value of 1 or 2; v has a value of 1 or 2; and
A is a hydrogen, sodium, potassium or lithium atom
or an NH4 group.
Exemplary phosphate esters which are useful
in practicing the present inv~ntion include, but are
not limited to,
CH3 0
..
C4H9(o-cH2-c)2oo-p-oH
H OH
CH3 0
..
C4Hg(O-CH2-C)sO-P-OH
H OH
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C, H3 ,O,
C4Hg (O-CH2-C)440-P-OH
H OH
C~13
C4Hg ( O - CH2 - C ~ 2 ( OCH2 - CH2 ) ;~ 50 -P -OH
H Off
~H3 ,,
4Hg (o-cH2-c)l4(ocH2-cH2)l9~-p-oH
H OH
GH3 ..
4Hg ~O-CH~-C)34(0cH2-c~2)450-P-oH
H OH
CH3
4Hg ( OCH2- C ) 10 ( OCH2 ~ CH2 ) 42 ~P, OH
H OH
, 3 "
H3 (OCH2-C)s O P - O Na
H OH
~-1467g
o CH3
.. I ,.
CH3 C (ocH2-c)2(ocH2c~2)2~5 P ONH4
OH
Generally, the phosphate es~ers may be
prepared by the phosphorylation of a hydroxy
endblocked polyalkylene oxide with polyphosphoric
acid or phosphorus pentoxide. It is believed that
phosphorylation is preferably conducted in such a
manner as to maximize mono-ester formation and
minimize ~ormation of diorgano phosphate esters and
free phosphoric acid. See U.S. Patent 3,235,627 and
U.S. Patent 4 t 4161830.
In addition to the silylated copolyethers
and the phosphate es~ers, the dispersin~ agent may
optionally contain the followlng:
(a) Ancillary wetting agents ~e.g.
lecithin);
(b) Acid scavengers (e.g. propylene oxtde);
~ c) Organomodified silicone fluids to
modify surface tension, surface lubricity or reduce
static charge; and
~ d) Adhesion promoters.
The ratio of silylated copolyethers to
phosphate esters is from 10:90 to 99:1, preferably
25:75 to 75:25.
The ratio of isocyanato silane to phosphate
ester is from 35:65 to 99:1 preferably 50:50 to
~0:10,
The manner in which the dispersing agent
acts to disperse the ferromagnetic particles is
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~: i;5~
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sllb~ect to scientific con3ecture and may lnvolve two
separate stages, each requiring a speci~ic
componen~. The understanding o~ ~his mechanism ia
not, however, a critical aspect o~ thls inventlon.
One component of this present invention ls
a low molecular weight anionic polyether ester acid
phosphate which ia sorbed on the ferromagnetic
particle. In this firs~ stage sorption, the
erromagnetic par~lcles acquire a greater charge and
are subsequen~ly separated by electrostatic
repulsion which counteracts the usual magnetic
forces of at~rac~ion. Because most magnetic coating
formulations are typic~lly nonaqueous9 thls
electrokinetic e~fect resides close to the
ferromagnetic partlcle surface. Consequently this
first stage sorption gives ~ quic~ but short range
separation that ~nitia~es the deagglomeration
process .
This limited separation exposes
ferromagnetic particle surface area to a second
stage sorption of a higher molecul~r welgh~
polyether silane which may ultimately covalently
bond to the ferromagnetic particle via Si-O
linkages. The bulky silylated polyether acts to
further increase an~ maintain ferromagnetic part~cle
separation. Since the force of magnetic attraction
diminishes wlth the distsnce of pa~ticle sepsration,
agglomerates are effectively deagglomerated and ~he
~ndency to reagglomerate is diminlshed.
Additional f~ctors may also be involved.
The polyalkylene oxide mo~ety present in either
component of the lnvention i~ believed to facilit~te
desorption of air and wster from the ferromagnetic
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., , .. .. .... - -
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particle surface, render the particle surface more
organophilic and therefore more susceptible to
wetting by the organic solvent and/or the polymer
binder.
Other agents used in the preparation of the
magnetic coating include, but are not limited to
organic solvents (acetone, MEK, THF, DMF); thermo-
plastic polymeric binder (polyurethane, PVC, phenoxy
resin, acrylic resin, cellulosic resins); thermoset
resins (epoxy); electron beam curable oligomers
(urethane acrylates~; cross linkers or curing agents
(polyisocyanates); lubricating agents (silicone
fluids, organomodified silicone fluids, fatty acids
and corresponding derivatives); antistatic agents
(halo- and quarternary nitrogen compounds);
conductive pigments (carbon black); wetting agents
(lecithin, "Aerosol OTT~"), and additional silanes
to improve adhesion or other properties.
The dispersing agent may be either
pretreated onto the ferromagnetic particles from
aqu~ous or organic solvent slurry or integrally
added to the coating formulation.
In general the magnetic recording medium
consists of a support having thereon a magnetizable
recording layer in which the ferromagnetic particles
are dispersed in a binder, the contained
ferromagnetic particles having been processed with
the dispersing agent of the present invention.
The magnetizable powders which can be used
in the present invention include the generally known
and conventional ferromagnetic powders. Suitable
ferromagnetic powders are y-Fe203, Co doped
D-14679
~2~5'~
y-Fe2O3, Fe3O4, Co-doped Fe3O4,
CrO2, ferromagnetic alloy powders or mixtures
thereof. Specific Pxamples of these ferromagnetic
alloy powders are as follows: Fe-Co, Fe-Ni,
Fe-Co-Ni-, Fe-Ni-Zn, Fe-Mn-Zn, Fe-Co-Ni-B,
Fe-Co-Ni-Cu-Zn, Fe-Co-Ni-Cr, Fe-Co-Ni-P, Fe-Ga-As,
Fe-As-Te, Fe-Mn, Zn-Cr, Ni-Co, Ni-Cu, Ni-Cr, Co-Mn,
Co-Mg, Ni-Co-As-Sb, Ni-Co-As-Sb, Cr-Ga-As, Cr-As-Te,
and Cr-As-Sb, and the like.
These alloys are well-known in the art and
are described in U.S. Pat. Nos. 3,026,215;
3,031,341; 3,1Q0,194; 3,242,005 and 3,389,014;
British Pat. Nos. 752,659; 782,762 and 1,007,323;
French Pat. No. 1,107,654; German Pat. No. OLS
1,281,334. These ferromagnetic powders are
generally used at about 300 parts by weight in a
binder at a level of about 50 to sbout 200 parts by
wt., preferably 70 to 150 parts by wt. The particle
size range of the ferromagnetic powder generally
employed is a particle size of 0.2 to 2 micrometers
in length, with an aspect ratio of 1/1 to 20/1.
Solid additive particles generally present
in the magnetizable layer are inorganic particles
such as carbon black, graphite, molybdenum
disulfide, tungsten disulfide, clay, silica,
carbonates, alumina powder, abrasive materials,
metal oxides, etc., and these are particularly
effective. Organic particles such ~s fine powders
of $1uorine-contRining resins, polyolefin resins,
polyamide resins, etc., can also be incorporated
with no particular detrimental influences. The
fluorine-containing resins gener&lly ha~e a
molecular weight from about 80,000 to about 120,000
D-14679
L L~
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and are materi~ls such as trifluorochloroethylene,
tetrafluorethylene, etc., the polyoleÇins reslns
generally have a molecular weight o~ abou~ 800,000
to about 1,200,000 and are materials such 8S
po~yethylene, polypropylene, e~c., and the polyam~de
resins generally have a molecular weight of abou~
5, ono to about 200~000 and are materials such as
6-nylon, 6~6-nylon, 6,10-nylon, 7-nylon, 9-nylon,
ll-nylon, and ~he like. These materials are
described in Japanese Patent Publicat~on Nos.
40461/71 and 3~001/7~. These solid additive
particles are added, in part~cular, as antistatic
agents, lubricants, surace-ma~ting agents or a tape
dursbility-improving agents as described in U.S.
Pat. Nos. 3,2.~3,n66; 2,~58,106; 3,312,563; 3,517,378
and 3,630,914. They are o~ten utilized generally in
the production o~ tapes a~ a level of ~bout 0.1 to
25 wt.~, preferably 0.2 to 13 wt.~, of the inorganic
or organic particles per 100~ by wt. of the
ferromagnetic powder; with particle sizes of about
0.02 to about 2 microns, preferably 0.08 to 1
micrometers, being generally used.
As the binder used fo~ the recordlng layer
in the present invention, 8 conventionally known
thermoplastic resin, thermosetting resin, (or
reaction-type resin) or mixtures thereof are used.
As the thermoplastic resins, those having
softening point o less th~n 150C, a mean molecul~r
weight of about 10,000 to about 200,000 Rnd a
copolymerization degree of about 400 to about 500,
such as vinyl chloride-vinyl acetate copolymers,
vinyl chloride-vinylidene chloride copolymers, vinyl
chloride-~crylonitrlle copolymers,
~-14679
-- -- .
~ ~s~
acrylate-acrylonitrile copolymers,
acrylate-vinylidene chloride copolymers,
acrylate-stryene copolymers,
methacrylate-acrylonitrile copolymers,
me~hacrylate-Yinylidene chloride copolymers,
meehacrylate-styrene copolymers, urethane
elastomers, polyvinyl Eluorides, vlnylldene
chloride-acrylonitrile copolymers J
bu~adiene-acrylonitrile copolymers, polyamide
resins, polyvlnyl bu~yrals, cellulose derivatives
(such as cellulose diacetate cellulose triaceta~e,
cellulose propionate, cellulose acetate butyrflte,
nitrocellulose etc.), styrene-butadiene copolymers,
polyester resins, chlorovinyl ether-acrylate
copolymers, amino resins, various synthetlc rubber
thermoplastic resins, and the like, are used.
The thermose~ting resin or resction-type
resin used pre~erably has a molecular weight of les~
than about 200l000 in the state of a coating
solution and, upon heat~ng after coating and drying,
the molecular weight becomes infinite due to the
reaction of condensatlon, addition, etc. Of ~hese
resins, those which are not softened or melted
be~ore the thermal condensation are preferred. To
be specific, there are, for example, phenol resins,
urea resins, melam~ne resins, alkyd resins, ~illcone
resins, acrylic reactive resins, epoxy-polyamide
resins, a mix~ure of a high molecular weight
polyester resin and an isocyanate prepolymer, 8
mixture of a methacrylate copolymer and a
diisocyanate prepolymer 9 a mixture of polyester
polyol and a polylæocyanate, urea-formaldehyde
D-14679
~2~5~
resins, ~ mixture of ~ low molecul~r weight
glycol/high moler:ular weight
diol/triphenylmethane-isocyanate, polyamide resins
and mixtures thereof~
The magnetic record~ng layer may be formed
by dissolving the above-descr~bed composition in sn
organic solvent and applying the resulting coating
snlut~on to the base support. As the organic
solvent used upon coat~ng, there can be employed
ketones such as acetone, methyl ethyl ketone, methyl
isobutyl ketone, cyclohexanone, etc., alcohols such
as me~hanol, ethanol, propanol, butanol, etc.,
esters such as methyl acetste, ethyl acetate, butyl
acetate, proply aceta~e, amyl ace~ate, ethyl
lactate, glycol acetate monoethyl ether, etc.;
ethers; glycol ethers such as glycol dimethyl ether,
glycol monoethyl ether, dioxane, etc.; aromatic
hydrocarbons such as benzene, toluene, xylene, etc.;
chlorlnated hydrocarbons such as methylene chloride9
ethylene chloride, carbon tetr~chloride, chloroform,
trichloroethane, dichlorobenzene, and the like. The
magnetic recording layer may also be a water-borne
formulation or an electron beam curable formulation.
Suitable support~ which can be used ~n the
p~esent inven~ion ~re those having a th~ckness of
about 5 to 50 ~, preferably 10 to 40 ~, and
suitable examples of supports are supports o~
polyesters such as polyethylene terephthalate;
polyolefins such 8S polypropylene; cellulose
deriva~ves such as cellulose triacetate, cellulose
diacetate; polycarbonate, and the like.
D-14679
5~
Whereas the exact scope of the instant
invention is set forth in the appended claims, the
followlng specific examples illustrate certain
aspects of the present invention and, mor~
particularly, point out methods o~ evaluating the
same. However, the examples are set forth for
illustration only and are not to be cons~rued as
limitations on the present ~nvention except ~ set
forth ~n the appended cl~ims. All p~rts and
percen~ages are by weight unless otherwise specified.
ExamPles:
~ ow viscosity values ~re ~ measure of
effective performance and probably indicative of one
or more of the following concomit~nt advant~ges:
R) higher loading of magnetic iron oxide. (i.e.,
higher information stor&ge dens~ty), b) reduced
grinding time, and/or c) reduced surfact~nt demand.
DEFINITIONS
A. G~f~c RE-610; MW 800
A mixture containing the following componen~s wlth
typical concentration~:
HlgCg ~3 OH
Cg~ ~ ~OCH2cH2)Il ~ ~ -P-OH (26 mole%)
MW ~ 800
D-14679
~2~ g
-- 19 --
Free Phosphoric Acid (11 mole %)
o
HO-P-OH
bH
Water 0.5 wt% max
B. Soya Lecithin (Central 3F-UB or Centrolexl~ P
from Central Soya Corp.)
A mixture. A phophatide residue from manu-
facture o~ soybean oi]..
A major ~~ 60-70%) component
H2C-C-OCR
o CH3
11 1+
H C O P OCH2 C~l2 3 OH-
O I
~¦ OH CH3
H2C-C-OCR
~-Phosphatidylcholine
R = typically C16-C 18
D-14679
'~
~i5~ L~
- 20 -
Gandidate DisPersants
S-l ( C3H6)27(OC2H4)24OC3H6Si(OMe)3
S-2 - y-Isocyanato$rlethoxys~1ane
S-3 - y-Aminopropyltriethoxysil~ne
S 4 CH~o(c~H4o)l2(cH2)3si(o ~3)3
S-5 - C4HgO (C3H6O)5(CH2)3 ( 3 3
S-6 - CH~CCH3COO(CH2)3Si(OCH3)3
S-7 - 1:1 wt blend of S-6 ~nd S-8
S B CH3O(cH2cH2O)75 3 6 S 3)3
P-l
Bu(OC3H6)20 O 1 40 - 85 mole~
OH
MW ~ 1,300
Corresponding Diorganic ~ster 2 - 20 mole~
Free Phosphoric Acid 2 - 45 mole~
P-2 - Composi~lon prepared by phosphoryl~tion
f~C3H6)17 O
MW ~ 1040
CH3
P-3 - C4Hg O(cH~cH2o)l8(~2ct-o~l4H
H
D-14679
- 21 -
O CH O
ll 1 3 11
P-4 - (Cyclophos PV4): HOP O (CH2CH20)4(CHCH2)250 1 OH
OH
The results are attached as follows:
PROCEDURE I
PREPARATION OF ~AGNETIC COATINGS
WET GRIND
2.06 grams of the dispersant candidate is
first dissolved in 32.2 grams of cyclohexanone
solvent. To this solution are added 51.4 grams dry
magnetic iron oxide and 25.0 grams Polyurethane
Solution (15.0 wt.% "EstaneT~" 5701F-l in a
cyclohexanone solvent). Initial premixing is done
with a hand spa~ula to wet all ingredients. The
resultant slurry is then ground at 3,500 rpm for 30
minutes on an Eiger Mini-50 Motor Mill.
LET DOWN
To the Wet Grind, 32.0 grams of
Polyurethane Solution are slowly added while
grinding. Then grinding is continued at 3,500 rpm
for additional 30 minutes on the Eiger Mini-50 Motor
Mill.
The final dispersion contains 4.00 wt.%
dispersant candidate based upon the weight of
contained magnetic iron oxide.
D-14679
~`~
- 22 -
Final DisPersion Cast Film
Wt.% ol.~ Wt.~ Vol.
Compon~nt
Magnetic Iron Oxide 36.03 10.41 82.9 54.5
Polyureth~ne Binder 5.99 6.72 13.8 35.2
Dispersant Candidate 1.44 1.96 3.3 10~3
CyGlohexanone
Solvent 56.54 80.91 -~
10~.O 100.0 1~0.O100.O
PROCEDURE II
PREPARATION OF CAST FILMS
A 50 mil wet film ls ~ast on
silicone-coa~ed release paper and air dried for one
week. The dried fllm is stripped rom the release
paper, cut into test strips and allowed to air dry
for an additional week.
PROCEDURE III
PREPARATION OF ~I.ECTRON B~AM
CURA~LE MAGNETIC COATING
WET GRIND
1.63 grams of the dispersant candidate is
first dissolved in 15.00 grsms af cyclohexanone
solvent. To ~his solution are added 34.09 grfims of
dry magnetic iron oxide and 19.44 grams of an
electron beam curable polyurethflne resin solution
(RD 4345-63 from Lord Gorp, a medium molecular
weight resin as a 58 wt.~ solution in
cyclohexanone). Initlsl premixing is done with a
hard spatula to wet all in8redients. The resultant
slurry is ~hen ground at 3500 rpm for 30 minute~ on
an Eiger-Mini-50 motor m~ll.
D-14679
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- ~3 -
I.ET DOWN
To the Wet Grlnd an additional 29.84 gram~
of cyclohexanone are slowly added while grinding.
Then g~inding ts cont~nued at 3500 rpm for an
additional 30 minutes on the Eiger Mini-50 motor
mill.
The final dispersion contains 4.7~ wt.
dispersant candidate based on the weight of
contained magne~ic iron oxide.
Final Formulstion
Final DisPersion Cast Film
Component Wt.%Vol.~ Wt.% Vol.~
Magnetic Iron Oxide 34.09 9.77 7~.53 39.84
Polyurethane Reætn
Solids 11.2812.56 24.00 51.20
Dispersant Candidate 1.63 2.20 3.47 8.96
Cyclohexanone 53.0075.47 --- ---
100.00100.00 100.00100.00
TYPes of Ma~etic Iron Oxide
A = Hercules TMOG-642. High coercive
strength ~Coercive Force = 650 Oersteds),
Cobalts Doped y-Fe~03. Acicular
particle, length = 0.20 micrometers,
sspect ration = 8-10.
B = Pflzer "Pferrox" 22~HC, y-Fe2O3
with no cobalt dopant. Coercive orce
(oersteds) J 350; Speciftc Magnetization
(emulg), 74; Average length
D-14~7~
. " ,. . . .
~2 E;~
- 24 ~
(micrometers), 0.35; Average width
(microme~ers), 0.06; Acicul~rity ~atio,
6; Poder Density (g/cm3), 0.8; Particle
Density ~g/cm3), 4.7; pH, 3.0; Oil
Absorption (mlJ100 g), 50; Specific
Surface Area (m Ig), 24.
PolYmeric Binder
"Estane" 5701F-l is ~ block copolymer
having a gl~ss transition temperature of
-28C. It consists o~ 60% soft block and
40~ hard block. The sof~ block ~s
~2,000 MW polyes~er of Adipic ~cid and
1,4-But~nediol. The hard block is
~1,500 MW polyurethane prepared from
4,4'-Diisocyanate Diphenyl Methane and
1,4-Butanediol.
Method of Introducln~ DisPersant
C = Integral Addition, i.e., dissolving of
dispers~ng agent in cyclohexanone olvent
prior to addltion of untreated magnetic
iron oxide and polyurethane binder.
Formulation detail in Procedure I.
D = Pretreatment of dispersing agent on
magn2t1c iron ox~de in ~oluene slurry.
Pretrea~ed oxide is vscuum dried for two
hours @ 120C. In prepsring subsequent
disper$10n (Procedure I) magnetic iron
oxide content corrected for weight of
dispersing agent pretreatment.
D-14$79
- 25 -
E = Pretreatment of dispersing agent on
magnetic iron oxide in water slurry.
Same drying conditions and dlspersion
preparation considerations as for (~).
TABLE I - Viscosity values achieved with
various disper~ing agents made from
Procedure I obtained at 25C us~ng a
Wells-Brookfield cone and plate
viscometer. Shear thinning index is
viscosity at 1 reciprocal second
divided by viscosity a~ 200
reciprocal seconds. The thixotropic
degree represents the hysterysis of
the rheogram.
TABLE II - Cast film properties achieved on
~ilms made from with various
disperslng agents mad~. from
Procedure I. The films are made by
Procedure II.
TABLE III - Y~scosi~y values achleved with
various dispersing agents made from
Procedure III.
TAB~E IV - Provldes a gene~ic description of
the m~gnetic iron oxide, polymeric
binder, candida~e organosili~-on
dispersing agents and dispersing
agen~s ~valuated. Mode of
introducing candidate d~sper~ant
also deflned.
D-14679
~Çi5~
-26 -
TABLE I
E CANDIDATE DISPERSANT METHOD TYPE DlSPERSlON RHEOLOGY
~ OF OF
A Candidate WT X INTRO- MAGNETIC VIS. VIS. SHEAR OEGREE
MBASED DUCING IRON (cps.) (cps.) THINNING OF
PON DISPER- OXIDE @ @INDEX THIXO-
LMAGNETIC SANT USED 1.0 200TROPY
EOXIDE _ SEÇ.-l SEC.-l X
A N~ne - - A113,0003,650 31.0 45
8 None - - B61,4001,400 42.6 10
1 S-l (2.0X)
P-l (2.0X~ 4.0 C A15,700 950 16.5 17
2 S-l (2.0Y.)
P-l (2.0%) 4.0 D A18,900 940 20.0 17
3 S-l (2.0%)
P-l (`2.0X) 4.0 E A14,200 660 21.4 22
4 S-l (2.0%)
P-l (2.0%) 4.0 C B9,440 440 21.4 22
C "Gafac'~'`
RE-610 4.0 C A44,0001,460 30.1 11
D "Gafacr~"
RE-610 4.0 C B20,500870 23.6 31
E P-l 4~0 C A39,2001,270 30.9 20
E S-l 4.0 C A55,0002,340 23.5
P-l ~2.0X)
S-2 (2.0%) 4.0 C A31,400 1,770 17.7 BO
G P-l (2.0æ)
S-3 (1.0%)
P-3 (l.OZ) 4.0 C A23,600 1,720 13.7 93
6 P-l (2.0Z)
S-4 (2.0%) 4.0 C A34,600 1,450 Z3.9 14
D-14679
A`
~6S~
- 27 -
~L__E I (CONT'D.)
E CANDIDATE DISPERSANT METHOD TYPE DISPERSION RHEOLOGY
X OF OF
A Candidate WT % INTRO- MAGNETIC VIS. VIS. SHEAR DEGREE
M BASED DUCING IRON (cps.) (cps.) THINNING OF
P ON DISPER- OXIDE @ @ INDEX THIXO-
L MAGNETIC SANT USED 1.0 200 TROPY
F OXIDE SEC.-l SEC.-l X
7 P-l (2.0%)
S-5 (2.0%) 4.0 C A 56,600 2,330 24.3 25
H Soya
Leci thi n ( Z . 0~0)
S-l (2.0%) 4~0 C A 70,800 2,850 25.0 56
I GaFac'~ RE-610 (2.0%)
S-l (2.0%~ 4.0 C A55,100 1,860 Z9.6 11
8 P-2 (2.0%)
S-l (2.0~.) 4.0 C A56,500 2,220 25.4 11
9 P-2 (2.0%)
S-l (2.0%) 4.0 C A70,000 2,320 30.5 4
J "Cyclophos" (2.0%)
S-l (2.0%) 4.0 C A 31,500 1,420 22.2 50
10 S-l (l.OX)
p_l ( 1 ~ 0%)
"Gafac~" RE-610
(2.0~) 4.0 C A 17,300 63027.5 27
S-2 4.0 C A 42,400 1,990 21.3 59
11 S-3 (2.0X)
P-3 (2.0%) 4.0 C A44,000 1,750 25.1 21
L Soya
Lecithin 4.0 C A40,900 1,670 24.5 27
12 1.0% P-l
3.0% S-l 4.0 C A22,000 1,650 13.3 85
13 2.0% P-l
2.0% S-l 4.0 C A15,700 77120.4 50
D-14679
~:65~
- 28 -
TABLE I ( GONT ' D . )
E CANDIDATE DISPERSANT METHOD N PE DISPERSION RHEOLOGYX OF OF
A Ca~d;date WT S INTRO- MAGNETIC YIS. VIS. SllAR DEGRE
BASED DUCING IRGN ~cps.~ (cps.) THINNING OF
P ON DISPER- OXIDE ~ e INDEX THIXO-
L MAGNETIC SANT USED 1.0 2~0 TROPY
E OXIDE _ _ SEC.-I_ SEC.-I
14 3.0S P-l
1.0~ S-l4.0 C A 31,500 1,000 31.5 10
15 3.0~ S-2
1.0~ P-l4.0 C A 18,9D0 76U 24.9 67
16 2.0~ ~-2
2.0% P-l4.0 C A 26,700 849 32 12
17 2.0~ S-2
2.0% P-l4.0 C A 31,40D 1770 17.7
18 1.0~ S-2
~0~ P-l 4.0 C A 3~,300 1,340 29.4 40
D-14679
~26~
_ ~9 _
TABLE I I
E CANDIDATE DISPERSANT METHOD TYPE CAST FILM PROPERTIES
X OF OF
A Candidate WT ~ INTRO- MAGNETICGl~ssT~nsil~
M ~ASED DUCING IRON ~ Str~ngth
P 0~ DISPER- OXIDE 60 (psi)
L MAGNETICSANT USED
E _ ~X I DE
I S-l (2.0~)
P-l (2~0~) 4.0 C A 47.1 799
2 S-l (2.0~
P-l (2.0S) 4.0 D A
3 S-l (2.0~)
P-l (2.Q%) 4.0 E A
4 S-l (~.0~)
P-l (2.C~ 4.0 C B
C "6~
R 4 104.0 C A 81.7 553
P-l 4.0 C A 29.3 445
F S-7 4.0 C A 24.7
P-l (2.0%)
S-2 (2.CS) 4.0 C A 11.9 571
6 P-l (2.0~)
S-3 (1.00
P-3 (I.QS) 4.0 C A 33.0
D- 14679
~59L~
- 30 -
TABLE~ CONT ' D.
-
E CANDIDATE DISPERSANT METHOD TYPE CAST FILU PROPERTIES
X OF OF
A Candida~e WT S INTRO- MAGNETIC Gloss Tensi 19
~ i~ASED DUCIN6 IRON ~S~r~ngth
P ON DISPER- OXIDE 60 (psi)
L MAGNETICSANT USU
E OXIi~E
I Ga~c R-610 t2.0%)
S-l t2.G%~ 4.0 C A 63 8S6
8 P-2 l2.0~)
S-l t2.0~) 4.0 C A 61.4
P-2 ~2.G~)
S-l t2.0a~ 4.0 C A 4B.5
J ~Cyclophos~ t2.00
S-l t2.0~ 4.0 C A 15.6
S-l tl.O~)
p_ I ~ I .OX)
nGa~acn RE-610
t2.0~) 4.0 C A 31.6 531-
K S-2 4.0 C A 13.6 737
I I p_3 ~2.CS)
S-3 t2.0$) 4.0 C A 40.3 593
D-14679
~ . . . .
~2Ç~
- 31 -
TABLE I I I
.
E CANDIDATE DISPERSANT METHOD TYPE DISPERSION RHEOLOGY
X OF OF
A Cand;d3ts ~T ~ INTRO- MAGNETIC YIS. VIS. SHEAR DEGREE
M BASED DUCING IRON (cps.) tcps.) THINNING OF
P ON DISPER- OXIDE ~ ~ INDEX THIXO-
L MAGNETIC SANT USED 1.0 200 TROPY
E OXIDE SEC~-I SEC.-I _ S
M Non9 - - A73,900 417 177
N ~C9ntrol~x P" C A 15,700 330 47.6 60
LQclthin Fr x
t~ntrol Soya 4.78
i9 S-l (2.39)
P-l (2.39) 4.78 C A 4,720 181 26.166
0 ~6~fac RE610~
4.78 C A 7,865 î97 40.060
P P-l 4.78 C A7, K 5 189 41.740
Q S-2 4.78 C A12,600 236 53.450
R S-l 4.78 C A14,200 354 40.133
S S-6 4.78 C A26,7t~ 393 68.029
T S-3 4.78 C A28>300 684 41.4î61
U S-7 4.78 C A31,500 629 50.03D
S-2 (2.39)
P-l (2.39) 4.78 C A 9,439 244 38.7 33
21 S-2 t~.59)
P-l (1.19) 4.78 C A î5,731 346 45.5 30
D - 1 4679
