Magnetic coating compositions containing fluoropolyols

A class of fluorinated polyols which when added to formulated dispersions used to make a magnetic particle based coating not only improves the dispersion of the particles in the formulation during manufacture but also improves the wear characteristics of the cured coating during use. The fluorinated polyol may be prepared either by the reaction of a diglycidyl ether with a diol or by the reaction of two diols with epichlorohydrin.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to improved magnetic coating compositions and 
magnetic recording media produced with such compositions, as well as 
certain novel fluoropolyols. 
2. Description of the Prior Art 
Audio, video, computer, and other magnetic recording tapes and disks are 
subject to extensive wear during use. During both recording and playback 
the magnetic medium is in frictional contact with the read/write head 
resulting in abrasion of its surface with concommitant loss of signal, 
read/write head wear, and even audible squeal. Because of such wear the 
lubrication of magnetic media used in tape, disk, and other applications 
has played an important part in their development (See R. H. Perry and A. 
A. Nishimura, Kirk-Othmer: Encyclopedia of Chemical Technology 14, 732-753 
(1981)). 
A magnetic recording tape or disk consists of a magnetic coating on a 
flexible or rigid (hard disk) nonmetallic substrate. Historically, these 
coatings have been made from a suspension of magnetic particles dispersed 
in an organic binder. More recently, magnetic films produced by direct 
sputtering of magnetic materials on the substrate have been developed. The 
present invention relates primarily to magnetic coatings based on pigment 
dispersion. 
Basic manufacture of a magnetic particle based system involves the coating 
on the substrate of choice with a formulated product containing pigment, 
organic binder, solvent, dispersants, lubricants, conductivity aids, and 
other miscellaneous additives. Dispersants are used to deagglomerate the 
magnetic particles and to provide for their maximum possible separation 
while maintaining maximum pigment-to-binder volume ratio. Magnetic tape 
performance is critically dependent on the nature of this dispersion and 
its volume ratio. Numerous dispersion agents have been used, such as 
lecithin, organic esters of phosphoric acid, organic acids, quaternary 
ammonium compounds, organic amines and miscellaneous surfactants. Of 
these, the more successful have been soya lecithin and synthetic phosphate 
esters. Lubricants are used to reduce the head-to-tape frictional 
interaction. Earlier versions and much of the current productions of 
magnetic tape involve the use of rather well known lubricants: fatty acids 
and esters, glyceryl esters, fatty acid amides, silicones, hydrocarbons 
and other refined oils. The selection of lubricant is not necessarily 
easy. The ideal lubricant must not only be compatible with the formulated 
coating solution during manufacture, but after cure and dry, must also 
migrate to the head-tape interface at the proper rate to provide lubricity 
yet not exude excessively to cause build-up on the head. The more common 
lubricants used include: isocetylstearate, butoxyethyl stearate, 
butylmyristate, silicone oils, and synthetic sperm oil. 
More recently, various fluorinated materials have been shown to be 
excellent high-performance lubricants. In particular perfluoroalkyl 
polyethers have been used on both magnetic pigment/binder and on sputtered 
magnetic film recording tapes. Because of incompatibilities with other 
components of the formulated magnetic coatings used for pigment/binder 
tape manufacture, the fluorinated materials are generally applied as a 
coating to the previously manufactured tape. This post-treatment 
represents a costly and unwanted step in the manufacturing process (see 
U.S. Pat. No. 3,778,308). 
The usual perfluorinated fluid or oil is essentially a non-polar material 
and, as such, has little tendency to bind itself or stick to the magnetic 
coating surface. When used as a lubricant film on the magnetic coating 
surface these materials are easily removed and therefore do not provide 
long term protection for the tape. Because of this, considerable effort 
has been expended to develop fluorinated materials with associated polar 
groups (see U.S. Pat. No. 4,696,845). The presence of these polar groups 
causes the fluorinated fluid to be strongly bound to the magnetic coating 
surface and to provide longer term protection to the tape. In some cases 
the non-polar fluorinated fluid can be used in conjunction with a second 
coating material which enhances its binding to the surface. In this latter 
case, a second, undesirable, post-treatment step in the manufacturing 
process is required (see U.S. Pat. No. 4,722,859). 
It would be desirable to provide a class of fluorinated materials which 
overcomes the problems discussed above yet provides long term wear for 
magnetic coated tape. It would also be desirable to provide a class of 
fluorinated materials which is an excellent dispersant for the magnetic 
pigments used and therefore enhances the overall performance of the tape. 
Certain fluoropolyols are known in the art. See, for example, U.S. Pat. 
Nos. 3,720,639; 3,852,222 and 4,284,747. It would be desirable to provide 
other, novel fluoropolyols which are useful, in particular, in magnetic 
coating compositions. 
SUMMARY OF THE INVENTION 
In accordance with this invention, there is provided a magnetic coating 
composition comprising a suspension of magnetic pigments in an organic 
binder, said organic binder comprising a fluoropolyol of the structure: 
##STR1## 
where X+Y=2-16, X.noteq.0 and where R.sub.f =C.sub.n F.sub.2n+1 for n=0-18 
and where R is selected from the group consisting of aliphatic radicals, 
aromatic radicals, cycloaliphatic radicals and fluorinated radicals. 
Preferably, R is: 
(a) an aliphatic radical such as 
--(CH.sub.2).sub.n -- for n=2-8 
or --(CH.sub.2 CHXO).sub.n -- for n=1-3 and X=H or CH.sub.3, 
or (b) an aromatic radical such as derived from resorcinol, or bisphenol A, 
or (c) a cycloaliphatic radical such as derived from cyclohexanediol or 
cyclohexanedimethanol 
or (d) a fluorinated radical such as 
--CH.sub.2 (CF.sub.2).sub.3 --CH.sub.2 -- 
or --CH.sub.2 --CH.sub.2 (CF.sub.2 --CF.sub.2).sub.n CH.sub.2 CH.sub.2 -- 
for n=1-4 
##STR2## 
It has been found that when the above polymeric fluoropolyols are added to 
conventional formulations of raw materials used to manufacture 
particle/binder based magnetic recording tape; they 
(1) form stable, compatible material compositions with no phase separation 
of solution components; 
(2) aid in the dispersion of magnetic pigments in the formulated 
composition during blending and in the subsequent cured/dried magnetic 
coating produced by this formulation, thereby improving coating 
performance; and 
(3) provide for a low energy, low friction, surface on the cured/dried 
magnetic coating, thereby improving its useful lifetime yet not requiring 
a post-treatment to obtain this improvement. 
Also in accordance with this invention there is provided a magnetic 
recording medium comprised of the magnetic coating of this invention 
coated onto either a flexible or rigid substrate. 
Further in accordance with this invention, there is provided a fluoropolyol 
having the structure 
##STR3## 
where X+Y=2-16, and X.noteq.0 and where R.sub.f =C.sub.n F.sub.2n+1 for 
n=1-18, and where R is selected from the group consisting of aliphatic 
radicals, aromatic radicals, cycloaliphatic radicals and fluorinated 
radicals selected from the group consisting of: 
--CH.sub.2 (CF.sub.2).sub.n --CH.sub.2 -- for n=3-7, 
--CH.sub.2 --CH.sub.2 (CF.sub.2 --CF.sub.2).sub.n CH.sub.2 CH.sub.2 -- for 
n=1-4 and 
##STR4## 
It has been found that these polymeric fluoropolyols are especially useful 
as additives for magnetic compositions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An ideal wear additive for magnetic pigment based formulations may be 
described, in part, as a material which on direct blending in the 
formulation forms a homogeneous, single phase mixture with the other 
solution components. During the curing process this ideal wear additive 
will concentrate on the surface of the dried magnetic coating and will be 
bound there in a more-or-less permanent state and will provide a low 
friction surface against the read/write head, thereby protecting the total 
system for a long period of time. The ideal additive is effective at low 
concentrations and will not interfere with the coating of the formulation 
on the selected substrate nor will it interfere with the magnetic 
performance of cured/dried magnetic coating. The fluoropolyols of the 
present invention are such ideal wear additives. When blended in magnetic 
pigment based formulations, they form homogeneous solutions with other 
solution components, they do not interfere with the coating process, they 
concentrate and are bound on the surface of the cured/dried coating, and 
they cause the formation of a low friction surface. 
An ideal dispersion aid for magnetic pigment based formulations may be 
described, in part, as a material which aids in the deagglomeration of the 
magnetic particles which are held together by magnetic attractions, 
reduces the time required to mill or blend the formulation, thereby 
avoiding undesirable reduction in magnetic pigment size, and helps 
maintain a maximum distance between particles in the cured/dried coating, 
thereby improving magnetic performance. The dispersion aid should not 
interfere with the coating process and should not interfere with the 
performance of the wear additive or lubricant used in the formulation. The 
fluoropolyols of the present invention are such an ideal dispersion aid. 
When blended in magnetic pigment based formulations, they reduce required 
mill times to achieve proper formulation dispersion, and they improve the 
magnetic performance of the magnetic coating. 
As will be seen, it has been found that the fluoropolyols of the present 
invention are, simultaneously, in fact, both an ideal wear additive and an 
ideal dispersion aid for magnetic pigment based magnetic coating media. 
It has been found that the polymeric fluoropolyols of the structure 
indicated below possess characteristics of both a conventional polyol and 
a conventional fluoropolymer. As with most polyols the hydroxyl groups of 
the fluoropolyol are reactive and may be crosslinked with various types of 
agents, such as multifunctional isocyanates, to form resinous materials, 
such as urethane resins. Some of the properties of these resins are 
similar to those of the non-fluorinated resin while some are more related 
to the properties of a fluororesin. For instance, the chemical and thermal 
stability of the urethane resins appear to be dependent on the presence of 
the urethane linkage, and thus the stability of the fluorourethane 
produced from these fluoropolyol appears to be of the same order as that 
for non-fluorinated urethanes. The fluorourethanes, however, posses many 
of the properties of a fluoropolymer: low moisture absorption, low 
moisture permeation, low dielectric constant, low index of refraction, and 
low surface energy. 
The fluoropolyols have the structure: 
##STR5## 
where X+Y=2-16, X.noteq.0 and where R.sub.f =C.sub.n F.sub.2n+1 for n=0-18 
and where R is: 
(a) an aliphatic radical such as 
--(CH.sub.2).sub.n -- for n=2-8 
or --(CH.sub.2 CHXO).sub.n -- for n=1-3 and X=H or CH.sub.3 
or (b) an aromatic radical such as derived from resorcinol, or bisphenol A 
or (c) a cycloaliphatic radical such as derived from cyclohexanediol or 
cyclohexanedimethanol 
or (d) a fluorinated radical, preferably a fluorinated aliphatic, aromatic 
or cycloaliphatic radical, such as 
--CH.sub.2 (CF.sub.2).sub.3 --CH.sub.2 -- 
or --CH.sub.2 --CH.sub.2 (CF.sub.2 --CF.sub.2).sub.n CH.sub.2 CH.sub.2 -- 
for n=1-4 
##STR6## 
The fluorinated polyols may be prepared either by the reaction of a 
diglycidyl ether with a diol (see U.S. Pat. No. 3,720,639 to Griffith) or 
by the reaction of the two diols with epichlorohydrin (see U.S. Pat. No. 
3,852,222 to Field et al.). 
The novel fluoropolyols of this invention have the structure: 
##STR7## 
where X+Y=2-16, and X.noteq.0 and where R.sub.f =C.sub.n F.sub.2n+1 for 
n=1-18, and where R is selected from the group consisting of aliphatic 
radicals, aromatic radicals, cyclocaliphatic radicals and fluorinated 
radicals selected from the group consisting of: 
--CH.sub.2 (CF.sub.2).sub.n --CH.sub.2 -- for n=3-7, 
--CH.sub.2 --CH.sub.2 (CF.sub.2 --CF.sub.2).sub.n CH.sub.2 CH.sub.2 -- for 
n=1-4 and 
##STR8## 
In the above structures, preferably X is 2 to 5 and Y is 2 to 5. 
Preferably, the aliphatic radicals have from 1 to 8 carbon atoms, the 
cycloaliphatic radicals have from 6 to 8 carbon atoms and the aromatic 
radicals have from 6 to 15 carbon atoms. Also preferably in the 
fluorinated radical --CH.sub.2 (CF.sub.2).sub.n --CH.sub.2, n=3. 
The aliphatic radicals are more preferably selected from the group of 
--(CH.sub.2).sub.n -- for n=2-8 or --(CH.sub.2 CHXO).sub.n -- for n=1-3 
and X=H or CH.sub.3 ; the aromatic radicals are more preferably selected 
from radicals derived from resorcinol or bisphenol A; and the 
cycloaliphatic radicals are more preferably selected from radicals derived 
from cyclohexanediol or cyclohexanedimethanol. 
In the most preferred fluoropolyols, R.sub.f is C.sub.8 F.sub.17 or C.sub.6 
F.sub.13 and R is either --CH.sub.2 (CF.sub.2).sub.3 --CH.sub.2 --, 
--(CH.sub.2).sub.4 --, a radical derived from bisphenol A, or 
##STR9## 
There are many well-known possible combinations of materials which may be 
used to formulate a particle based magnetic coating. As previously 
discussed, the basic formulated product used to cast a magnetic coating 
consists of a magnetic pigment, an organic binder, a conductivity agent, a 
dispersant, a lubricant, and a solvent. Magnetic pigments which have been 
used include oxides such as .gamma.-Fe.sub.2 O.sub.3, Co-containing 
.gamma.-Fe.sub.2 O.sub.3, surface doped Co-.gamma.-Fe.sub.2 O.sub.3, 
Fe.sub.3 O.sub.4, Co-containing Fe.sub.3 O.sub.4, CrO.sub.2 and Ba 
(FeO.sub.2).sub.2 or powders of magnetic metals such as Fe, Co, Ni, etc. 
Although various thermoplastic materials have been used as the organic 
binder, it is more common in recent times to use thermoset materials. 
These include: polyurethanes, polyesters, epoxies and phenoxies, cellulose 
nitrate, polyimides, polyvinylacetal, polyvinylbutyral, polycarbonates, 
polysulfones, phenol-formaldehyde resins, melamine-formaldehyde resins, 
polyacrylic esters, polyacrylic acid, and a variety of vinylchloride, 
vinylidene dichloride, and butadiene copolymers, and the like. Polyester 
urethanes are particularly important because of their superior mechanical 
properties. 
Conductivity agents are included in the formula to reduce the electrical 
resistance of the magnetic coating and to prevent static charge build-up. 
In general, one of numerous possible carbon blacks may be used for such 
purpose. As discussed above, a variety of materials may be used as 
dispersants including soya lecithin and various synthetic phosphate 
esters. Solvents are used to dissolve the binder resins and additives and 
to provide a fluid medium for the magnetic pigment dispersion. Common 
solvents employed include: tetrahydrofuran, cyclohexanone, methyl ethyl 
ketone, methyl isobutyl ketone, and toluene. 
In the present invention all practical combinations of the above materials 
may be used. When a fluoropolyol of the invention is used in these 
combinations, it aids in the dispersion of the pigment in the formulated 
product and imparts a low friction surface and reduced wear 
characteristics to the cured/dried magnetic coating. In essence it becomes 
part of the binder system and is bound at the surface of the magnetic 
coating. A variety of cross-linking agents may be used. Among the 
preferred ones is an aromatic polyisocyanate adduct based on toluene 
diisocyanate. In the presence of selected cross-linking agents the 
fluoropolyol is bound within and on the binder resin selected. The only 
criterion which the formulated product should meet is that the solution 
phase of the formulated materials, including the crosslinking agent if 
used, must form a homogeneous, single phase system. In some cases the 
fluoropolyol may be prereacted in the system to achieve this condition. 
When a fluoropolyol of the present invention is blended with most practical 
combinations of binder resins, a primary dispersant, and a solvent, it 
forms a homogeneous, non-separating system. When magnetic powders and 
conductivity aids are added to this blend and the resulting system is 
mixed and milled, the particles are rapidly dispersed and upon coating and 
curing form a film with optimal magnetic properties. The surface of this 
film possess a low coefficient of friction. 
It has been found that when the fluoropolyol is removed from the blend such 
that dispersion depends only on the primary dispersant, the milling time 
of the resultant formulation must be increased about 30 to 50% to achieve 
a similar level of magnetic performance. In addition, if the fluoropolyol 
is replaced in the blend with a conventional migrating lubricant, the 
coefficient of dynamic friction increases by about 5 to 30% and the wear 
characteristic of the system under practical use conditions is 
significantly impacted in an adverse way. 
The fluoropolyols of the present invention are considered as both wear 
additives and dispersion aids for magnetic pigment based coating systems. 
The fluoropolyols are typically present in the magnetic coating in an 
amount from about 0.5 to 20 weight percent based on the weight of the 
total binder system, and preferably about 1 to 12 weight percent. The 
other components may be present in their conventional amounts. The 
magnetic coating may be coated onto a flexible or rigid substrate (such as 
a tape of floppy disk) in any conventional manner. 
The following non-limiting examples are given to further understand the 
present invention. 
Examples 1 and 2 demonstrate the two basic methods for preparing the 
fluoropolyols of this invention. 
EXAMPLE 1 
To a 2 liter, 3 neck flask equipped with a water cooled condenser, a 
stirrer, a heating mantle and nitrogen purge tube were added 331 grams of 
Compound 1 (identified below--C.sub.8 Diol), 164 grams of Compound 2 
(identified below) and 500 ml of methylisobutyl ketone (MIBK). While 
stirring and heating this mixture to reflux, 81.4 grams of epichlorohydrin 
and 80 grams of 50% sodium hydroxide were slowly added. After reflux for 
30 hours the mixture was cooled, washed four times with water, and dried 
by azeotropic distillation of water with MIBK. The resulting polyol had a 
number average molecular weight of 4400 and a hydroxyl content of 1.5 
meq/g. 
EXAMPLE 2 
To a 12 liter, 3 neck flasked equipped with a water cooled condenser, a 
stirrer, a heating mantle and nitrogen purge tube were added 1880 grams of 
the diglycidyl ether of Compound 1 (C.sub.8 DGE), 820 grams of Compound 2, 
2000 ml of MIBK, 8 g of benzyltriethylammonium chloride, and 0.1 grams of 
potassium hydroxide. With stirring this mixture was heated to a maximum 
temperature of 110.degree. C. for 50 hours, cooled, washed four times with 
water, and dried by azeotropic distillation of water with MIBK. The 
resulting polyol had a number average molecular weight of 6600 and a 
hydroxyl content of 1.45 meq/g. 
Compounds 1 and 2 above refer to the following structures: 
______________________________________ 
##STR10## R.sub.f = C.sub.8 F.sub.17 for Compound 
1 or 1,3-benzene-dimethanol. 5-heptadecafluorooctyl 
2,2,2,2 tetrakis- (trifluoromethyl) 
R.sub.f = H for Compound 2 
or 
1,3-benzene-dimethanol 
2,2,2,2 tetrakis- 
(trifluoromethyl) 
______________________________________ 
EXAMPLES 3-9 
In Examples 3-9 the benefits of using the fluoropolyol of Example 2 in a 
simplified version of a magnetic coating composition is demonstrated and 
compared with those obtained using a common migrating lubricant, 
isocetylstearate. In these examples samples were prepared in laboratory 
jar mills and were milled according to a test protocol (two days for Phase 
1 components and three days for Phase 2) which has been found to simulate 
milling levels achieved in production sandmill equipment. Samples were 
hand coated onto 1 mil Mylar polyester film for testing purposes. When 
used, the crosslinking agent was added just prior to coating. Examples 3 
and 4 are comparative examples where no fluoropolyol was used. The results 
are shown in Table 1. The coated films were tested for magnetic and 
durability properties. The results are indicated below. 
TABLE 1 
__________________________________________________________________________ 
EXAMPLE NO. 3 4 5 6 7 8 9 
__________________________________________________________________________ 
COMPOSITION (Parts By Wt.) 
PHASE 1 
PIGMENT (1) 10 10 10 10 10 10 10 
DISPERSANT (2) .3 .3 .3 .3 .3 .3 .3 
FLUOROPOLYOL -- -- .1 .2 .25 .2 .25 
URETHANE (3) .3 .3 .3 .3 .3 .3 .3 
MEK (4) 50 50 50 50 50 50 50 
ICS (5) -- .3 -- -- -- -- -- 
PHASE 2 
URETHANE (3) 2.7 2.7 2.6 2.5 2.45 
2.2 2.05 
MEK 50 50 50 50 50 50 50 
CROSSLINK (6) -- -- -- -- -- .3 .4 
PERFORMANCE 
SQUARENESS (B.sub.r /B.sub.m) (7) 
.79 .82 .83 .86 .86 .85 .86 
STEINBERG DURABILITY 
1 2 2 8 12 22 28 
@ 8m/sec-50 gm (min) 
SCRATCH RESISTANCE (gm) (9) 
250 250 300 400 400 500 500 
COEFFICIENT OF FRICTION (10) 
.384 
.307 
.286 
.284 
.286 
.291 
.291 
__________________________________________________________________________ 
(1) --Fe.sub.2 O.sub.3 - 
(2) RE610, a phosphate ester from GAF Chemicals Corporation 
(3) Estane .RTM. 5715, a thermoplastic polyurethane from B. F. Goodrich 
(4) Methylethyl ketone solvent 
(5) Isocetylstearate 
(6) Mondur .RTM. CB75, a difunctional isocyanate which is an aromatic 
polyisocyanate adduct based on toluene diisocyanate from Mobay Chemical 
(7) The ratio of remanence to saturation magnetization (B.sub.r /B.sub.m) 
as measured on a magnetic hysteresis loop. 
(8) Durability as measured on a Model MDT 3000 Media Durability Tester 
from Steinberg Associates. This machine simulates wear of the magnetic 
media in still frame mode on a video cassette player. It determines time 
to failure in minutes as a function of tension (in grams) and head speed 
(meter/second). 
(9) As measured by a weighted stylus 
(10) As measured by an inclined plane. 
The larger squareness ratio of the magnetic coatings produced by samples 
containing fluoropolyol (Examples 5-9) compared with those that did not 
(Examples 3 and 4) is indicative of a greater degree of magnetic pigment 
dispersion in these compositions. This greater dispersivity is further 
indicated by a high gloss produced by the fluoropolyol containing 
materials. In the absence of crosslinking agent (Examples 5-7) the 
presence of the fluoropolyol greatly enhances the Steinberg Durability and 
scratch resistance of the coatings as compared with the isocetylstearate 
containing product (Example 4). Similarly, the coefficient of friction for 
the fluoropolyol composition is lower. The presence of crosslinking agent 
(Examples 8 and 9), which acts both to crosslink the binder resin and 
react the fluoropolyol into the total binder system, further toughens the 
system and increases its overall durability. The fluorine atom content on 
the surface of the fluoropolyol containing coatings was 35% as measured by 
X-ray Photoelectron Spectroscopy (ESCA). 
EXAMPLES 10-16 
In Examples 10-16 the benefit of using fluorinated polyols compared with a 
non-fluorinated material of similar structure is demonstrated. Polyols for 
these examples were prepared as in Examples 1 and 2 (except as noted 
below) and have the following general structures: 
______________________________________ 
##STR11## 
Specific structures include: 
Example No. 
R.sub.1 R.sub.2 
______________________________________ 
10 R.sub.3 R.sub.4 
11 R.sub.3 CH.sub.2 (CF.sub.2).sub.3 CH.sub.2 
12 R.sub.3 (CH.sub.2).sub.4 
13 R.sub.3 
##STR12## 
14 R.sub.4 (CH.sub.2).sub.4 
15 
##STR13## (CH.sub.2).sub.4 
______________________________________ 
##STR14## 
##STR15## 
For the polyol of Example 11, C.sub.8 DGE/Hexafluoropentanediol (HFPD), th 
procedure of Example 2 was followed except that the mixture was heated for 
40 hours. The resulting polyol had a number average molecular weight of 
2800 and a hydroxyl content of 1.80 meq/g. 
For the polyol of Example 12, C.sub.8 DGE/Butanediol (BD), the procedure of 
Example 2 was modified in that the charge was as follows: 1880 g of 
C.sub.8 DGE (2.00 mols), 180 g of BD diol (2.00 mols), 2000 ml of MIBK and 
1.0 ml of BF.sub.3 etherate catalyst. This mixture was heated at 
90.degree.-100.degree. C. for 7 hours until 95% of the reactants 
disappeared as determined by gas chromatography. The resulting polyol had 
a number average molecular weight of 2100 and a hydroxyl content of 2.2 
meq/g. 
For the polyol of Example 13, C.sub.8 Diol/Bisphenol A (BPA), the procedure 
of Example 1 was followed, except that the charge was as follows: 83 g of 
C.sub.8 Diol (0.1 mol), 20 g BPA (0.1) mol, 20.4 g epichlorohydrin (0.22 
mol) and 19 g sodium hydroxide (0.24 mol), and 100 ml MIBK. The mixture 
was heated at reflux (93.degree.-96.degree. C.) for 6 hours. The resulting 
polyol had a number average molecular weight of 2600. 
For the polyols of Examples 14 and 15, the procedure of Example 2 was 
followed. 
Formulations were prepared as above except that a vinyl co-binder was 
included in the Phase 1 mixture to further toughen the system. Performance 
evaluations were conducted as before. Examples 15 and 16 are comparative 
examples. The results are shown in Table 2. 
TABLE 2 
__________________________________________________________________________ 
EXAMPLE NO. 10 11 12 13 14 15 16 
__________________________________________________________________________ 
COMPOSITION (Parts By Wt.) 
PHASE 1.sup.(1) 
PIGMENT 10 10 10 10 10 10 10 
DISPERSANT .3 .3 .3 .3 .3 .3 .3 
POLYOL .25 .25 .25 .25 .25 .25 0 
CO-BINDER.sup.(2) 
.6 .6 .6 .6 .6 .6 .6 
MEK 50 50 50 50 50 50 50 
PHASE 2.sup.(1) 
URETHANE 2.15 
2.15 
2.15 
2.15 
2.15 
2.15 
2.15 
MEK 50 50 50 50 50 50 50 
CROSSLINK .18 .18 .18 .18 .18 .18 .18 
PERFORMANCE.sup.(1) 
SQUARENESS (B.sub.r /B.sub.m) 
.87 .83 .83 .86 .82 .85 .85 
STEINBERG DURABILITY 
@ 8m/sec-50 gm (min) 
30 30 30 30 30 21 12 
SCRATCH RESISTANCE (gm) 
500 500 500 500 450 300 150 
FRICTION .28 .28 .28 .28 .28 .32 .36 
__________________________________________________________________________ 
.sup.(1) As above except as noted 
.sup.(2) Vitel 200, an ester copolymer from Goodyear 
The high fluorine content provided by the fluorinated polyols of Examples 
10-14 causes them to segregate at the surface and through reactions with 
the crosslinking agent to produce a bound low energy fluorourethane film 
on the magnetic coating. In the absence of fluorine in the polyol (Example 
15) no segregation occurs and wear performance approaches that for a 
formulation with no lubricant at all (Example 16). A polyol of low 
fluorine content (Example 14) also appears capable of segregation and 
provides intermediate performance between that of polyols of higher 
fluorine content and those with no fluorine at all. 
EXAMPLES 17 AND 18 
The ability of the fluoropolyols to enhance the dispersion of magnetic 
pigments is further demonstrated in Examples 17 and 18 with Example 18 
being a comparative example. In these examples it is seen that the amount 
of milling time required to achieve maximal magnetic performance is 
significantly less in the presence of the fluoropolyol. Two co-binders, 
VAGH and VITEL 200, were included in the overall formulation in order to 
further enhance performance and more closely replicate a typical 
commercial system. The fluoropolyol of Example 2 was used and the 
compositions are indicated below in Table 3. 
TABLE 3 
______________________________________ 
EXAMPLE 17 
EXAMPLE 18 
______________________________________ 
PHASE 1.sup.(1) 
PIGMENT 100 100 
DISPERSANT 3 3 
FLUOROPOLYOL 2.5 -- 
VITEL 200 4.0 4.0 
VAGH (2) 2.0 2.0 
METHYLETHYL KETONE 
200 200 
ISOCETYLSTEARATE -- 3.0 
PHASE 2.sup.(1) 
URETHANE (3) 21.5 21.5 
MEK 200 200 
CROSSLINK 1.5 1.5 
______________________________________ 
.sup.(1) As above except as noted. 
.sup.(2) A vinyl copolymer from Union Carbide Corp. 
.sup.(3) Estane .RTM. 5740 .times. 719 from B. F. Goodrich. 
Using the above compositions, the formulations were prepared by adding in 
order Phase 1 solvent, dispersant, binders, fluoropolyol or ICS, and 
pigment to a 10 gallon tank and mixing with a high speed Cowles Dissolver 
for 30 min. This pre-mix was transferred to a 1.5 liter horizontal, glass 
bead (1.2 mm) mill operated at a 0.5 liter/min pump rate with a shaft 
speed of 10 M/sec. using an 87% chamber charge. After each pass of Phase 1 
dispersion through the mill at 50.degree. C., a hand coat on Mylar film 
was prepared and physical and magnetic properties measured. After 
completion of the fourth pass of Phase 1 components, the Phase 2 binder 
and solvent were added as a solution to the Phase 1 dispersion and the 
resulting mixture blended for 30 min in a Cowles Dissolver. This combined 
mixture was milled three times under the same conditions as Phase 1, and 
after each pass a hand coating on Mylar film was prepared and properties 
measured. For these latter three samples a crosslinking agent was added 
prior to coating the formulation. The results of physical and magnetic 
property measurements are as indicated in Table 4. 
TABLE 4 
__________________________________________________________________________ 
STEINBERG 
HC(1) @8M/SEC-50GM 
SQUARENESS 
(Oe) 
FRICTION 
MIN 
__________________________________________________________________________ 
EXAMPLE 17 
PHASE 1 PASS 
1 .62 640 -- -- 
2 .79 648 -- -- 
3 .86 650 -- -- 
4 .86 650 -- -- 
PHASE 2 PASS 
1 .83 651 .286 30 
2 .86 650 .274 30 
3 .86 650 .274 30 
EXAMPLE 18 
PHASE 1 PASS 
1 .51 637 -- -- 
2 .68 647 -- -- 
3 .76 649 -- -- 
4 .80 651 -- -- 
PHASE 2 PASS 
1 .74 645 .319 16 
2 .79 649 .312 18 
3 .81 650 .307 26 
__________________________________________________________________________ 
(1)Magnetic coercivity 
The sample containing fluoropolyol (Example 17) not only produces the 
larger squarness ratio, it achieves both its maximal magnetic properties 
values with fewer numbers of passes through the mill. Both squareness 
(B.sub.r /B.sub.m) and coercivity are directly related (other parameters 
being equal) to the degree of pigment dispersion in the coating. The 
ability of the fluoropolyol to aid in pigment dispersion is significant 
and can reduce overall milling costs in manufacturing formulated magnetic 
pigment products. 
EXAMPLES 19 AND 20 
In order to additionally demonstrate the benefits of the fluoropolyols of 
the present invention, a complete magnetic pigment formulation was 
prepared and used to make 5.25 inch floppy diskettes (Example 19). The 
performance of these disks was compared directly to those made from an 
identical formulated product containing isocetylstearate (Example 20) and 
to three commercially available disk products. The fluoropolyol of Example 
2 was used and the formulation used for this demonstration is as indicated 
in Table 5: 
TABLE 5 
______________________________________ 
EXAMPLE 19 
EXAMPLE 20 
______________________________________ 
PHASE 1.sup.(1) 
PIGMENT 100 100 
DISPERSANT 3 3 
CONDUCTIVITY AID.sup.(2) 
3 3 
ALUMINA.sup.(3) 2 2 
FLUOROPOLYOL 2.5 -- 
VITEL 200 4 4 
VAGH 2 2 
ISOCETYLSTEARATE -- 3 
METHYLETHYL KETONE 
200 200 
PHASE 2.sup.(1) 
URETHANE 21.5 21.5 
MEK 200 200 
CROSSLINK 1.5 1.5 
______________________________________ 
.sup.(1) As above, except as noted. 
.sup.(2) Pearl 2000, a carbon black from Cabot. 
.sup.(3) E140, an alumina abrasive from Norton. 
Both formulations were mixed as described for Examples 17 and 18 and were 
milled in the same glass bead mill. Phase 1 components were milled 3 times 
and the combined Phase 1/Phase 2 mixture was passed an additional 2 times 
through the mill. The completely dispersed mixtures were filtered for 8 
hours through a 3 micron filter, the crosslinking agent was added, and the 
formulas were coated on Mylar film and cured using automated equipment 
employing a Gravure coating head and a three zone furnace 
(130.degree.-180.degree. C.) operated at 400 ft/min. 
The coating was calandered using a Perkins model with 7 rolls employing a 
soft cotton roll with pressure of 1000 pounds per linear inch (PLI) at 
180.degree. F. and was also operated at 400 ft/min. A total of 500 disks 
of both formulas was made and jacketed using a Kendall 9007 rayon 
polyester liner. As before, the finished coated product containing 
fluoropolyol had a high gloss and slippery feel as compared to the 
isocetylstearate containing coating. The results are indicated in Table 6: 
TABLE 6 
__________________________________________________________________________ 
COMMERCIAL 
PRODUCT 
SAMPLE EXAMPLE 19 
EXAMPLE 20 
A B C 
__________________________________________________________________________ 
1) PHYSICAL PERFORMANCE 
SCRATCH (gm) 500 450 500 500 500 
FRICTION .186 .241 .241 
.194 
.241 
TORQUE-STARTING.sup.(1) 
.48 .79 .55 .56 .58 
(inch. oz) RUNNING .14 .39 .16 .17 .12 
PAD LOADING 
2.01 3.10 2.61 
2.54 
2.80 
STEINBERG (Min) 
8M/SEC 20 GM 30 30 ND.sup.(5) 
30 ND 
50 GM 30 26 ND 30 ND 
100 GM 30 20 ND 30 ND 
13M/SEC 20 GM 30 22 30 30 30 
50 GM 28 16 20 21 20 
100 GM 18 1 15 16 18 
OUT OF JACKET WEAR (Min).sup.(2) 
1000 RPM 50 GM 240 190 240 240 240 
100 GM 80 40 80 60 80 
500 GM 30 10 20 20 20 
2) MAGNETIC PERFORMANCE 
COERCIVITY (Oe) 650 650 ND 620 ND 
SQUARENESS.sup.(3) .51 .50 ND .53 ND 
SFD.sup.(4) .39 .46 ND .41 ND 
__________________________________________________________________________ 
.sup.(1) Operating torque as measured on a commercial disk drive. 
.sup.(2) Wear measured by determining the length of time in minutes until 
the output of a recorded signal on a single track is 70% lost while the 
read head is subjected to the specified force. 
.sup.(3) The magnetic pigments in a floppy disk product are not oriented. 
The theoretical squareness for such a coating is 0.50. 
.sup.(4) Switching field distributiona value for this parameter (&gt;.4) 
indicates poor pigment distribution. 
.sup.(5) Not determined. 
Inspection of this data indicates that the floppy disks made with the 
fluoropolyol (Example 19) is clearly superior to that made with 
isocetylstearate (Example 20). Where data is available the performance of 
the Example 19 products is also either equivalent or superior to all three 
commercially sold disks. 
It can be seen that the present invention provides a magnetic coating 
composition which provides coated products having excellent long term wear 
and other physical and magnetic properties. The fluoropolyols of this 
invention are excellent dispersants for the magnetic pigments used in such 
coating compositions.