Note: Descriptions are shown in the official language in which they were submitted.
~ ~5~9~
--1- 106,753 CAN/R~:G
RECORDING DISKETTE E~AVING FLOCKED-FIBER WIPING FABRIC
AND METHOD OF MAKING
Technical Field
This invention concerns recording media such as a
diskette which comprises a flexible magnetic recording
disk contained in a jacket to which is attached a wiping
fabric in facing relationship to the disk~ A typical
diskette is disclosed in U. S~ Patent No~ 3~663,658
Back~round
The wiping fabric of No. 3,668,558 comprises a
porous, low-friction, anti-static material which may be a :~
self-supporting dusting fabric. In most diskettes now on
the market, the wiping fabric is fused to a sheet of the
jacket material in point-contact patterns. Ultrasonic
welding is sometimes employed instead of heat~ Whether
laminated by heat or by ultrasonic welding, there have
been problems such as (1) delamination of self-supporting
fabrics from the diskette jacketsJ ~2) the fabric
scratching the surface of the recording disk, especially
by hard nodules created upon fusing the wiping abric to
the jacket sheet, and (3) torque variations, especially
when the fiber distribution in ~h~ fabric has been
nonuniform. A fourth problem stems from the tendency of
fibers to protrude from the wiping fabric into the jacket
openingst thus creating the hazard that the protruding
fibers mlght be picked up by the drive mechanism and
become trapped at the gap of the recording headsO
~t is believed that all commercial diskettes are
fabricated by cutting the wiping fabric to size and
adhering the cut pieces one at a time to individual sheets
of the jacket material, leaving edges of each jacket sheet
uncovered~ Each sheet i5 then die-cut to provide a
jacket blank; two edges which are not covered by the
wiping ~abric are folded and heat-sealed or otherwise
adhered to tha outer surface o the jacket blank to
.
.
9 ~ ~
provide an envelope; the recording disk is inserted; and a third ~mcovered
edge is folded and then adhered to the outer surface to enclose the disk.
There have been problems with adhesion of the folded edges to the underlying
jacket material.
Disclosure of Invention
The aforementioned problems may be eliminated in the present inven-
tion,
According to one aspect of the invention, there is provided a disk-
ette which comprises a thin jacket containing a flexible recording disk and a
~iping fabric bonded to the jacket in facing relationship to the disk, charac-
terized in that the wiping fabric comprises a layer of short, closely-spaced
fibers, one end of each fiber being bonded directly to the jacket.
; ~ccording to another aspect of the invention there is provided a
diskette jacket for a flexib]e recording disk) which jacket has wiping fabric
bonded to its inner~facing surfaces, characterized in that the wiping fabric
comprises a layer of short, closely~spaced fibers, one end of each fiber being
bonded dîrectly to the jacket,
According to another aspect of this invention there is provided a
method of making diskettes comprising the steps of bonding a wiping -Eabric to
jacket material, cutting this into jacket blanks and forming each blank into a
jacket to enclose a recording disk permanently, characterized in that the
iping fabric is bonded to the jacket material by applying a bonding agent to
the jacket material to prGvide an adhesive layer and embedding short, closely
spaced fibers into the adhesive layer, one end of each fiber being thus bonded
d~rectly to the jacket material.
The flocked-fiber layer of the diskette-may comprise fibers which
are predominantly 10 to 25 micrometers in diameter and 0.05 to 0.8 micrometers
in length. In order to meet present diskette specifications, the flocked-
~ 2 ~
"' '
~5~
fiber ]ayer, including any adhesive added to bond it to the jacket, may increase
the thickness of the jacket material about 0.15~0.3 D~D to provide an overall
thickness of the jacket material with its flocked~fiber layer of 0.35-0.~5 mm.
It may be necessary to calender the flocked-fiber layer in order to reduce it
to a desired thickness, thereby bending over free ends of the fibers which
; otherwise tend to be upstanding. Preferably the fibers of the flocked~fiber
layer are densely packed to about 17-102 g/m2, If the fibers were too fine or
too low-in density, ~he recording surface might not be kept sufficiently clean,
and the bonding agent might be exposed to scratch the recording surface. If
the fibers were too coarse or too high in density, there might be undesirable
variability in the torque required to rotate the disk.
Especially useful fibers for the flocked~fiber layer are rayon,
nylon, polyester, acrylic, COttOII and mixtures thereof.
The fibers may be attracted to the adhesive layer electrostatically
or merely by gravity. It is preferred that there be a beater~bar beneath the
jacket material to assist in driving the fibers into the viscous, tacky
adhesive layer.
The bondin~ agent preferably i~ a water~based adhesive. A hot~melt
adhesive may ~e used. The use of a solvent might ~e hazardous if the fibers
are attracted to tlle adhesive layer electrostatically. However, the use of
a sol~ent to activate the jacket material to an adhesive state provides certain
kn~wn econom~es. I~ the Jacket material comprises paper or otherwise has a
f~brous nature, an adhesive coating can serve the dual functions of integrating
t~o~e fibers and adhering the flocked~fiber layer.
Preferably the fibers of the flocked-fiber layer are treated with
an anti-static agent prior to flocking in order to provide a more uniform
flocked~fiber layer, as is well known in the flocking art, That anti-static
agent also enhances the ~leeding off of charges from the Dlagnetic recording
~ 3
'`
'
: :
~ ~5~9~
disk of the diske-tte. Even so, it may be desirable to apply an additional
anti-static coating to the fiber--flocked layer, preferably as an in-line
process. Also as an in-line process and, if desired, simultaneously with
application of an anti-static coating, a lubricant may be applied to the
flocked-fiber layer as in British Patent specification No. 1,508,227.
The flocked~fiber layer may be applied to a roll of the jacket
material continuously to provide roll stock from which individual jacket blanks
can later be die~cu~. This should permit an economical advantage compared
to the individual~jacket~sheet assembly procedures of the prior art.
lQ For economy of manufacture, the flocked~fiber layer may be applied
to cover one face of the jacke~ material, the width of which may be a multiple
of the width of an individual jacket. The fiber-flocked jacket material may
then be wound up for convenient storage and shipment. The flocked jacket
material may later be unwound and die~cut to provide individual jacket blanks,
each of which is folded and adhesively bonded to itself to enclose a magnetic
recording disk. If desired, adhesive material may be applied only to selected
areas of the jacket material, as by a gravure printing process, thus effecting
a small raw material savings in both the adhesive material and the fibers.
The need to maintain registration in the die~cukting step would offset at
least partially that cost saying.
A diskette prepared according to these principles makes it more
practical to use certain jacket materials that previously were believed to
require uneconomical procedures, e.g., paper, polycarbonate film, and biaxially~
oriented polyester film. ~hen using paper, the adhesive base for the flocked-
fiber layer can serve the additional function of stabilizing the paper~ a
function wh~ch previously would have required a separate operation. Polycar-
honate and polyester films have not been adaptable to prior techniques for
applying wiping fabric.
-.` ?
9 ~ ~
Blief Description of Drawings
Figure 1 schematically illustrates the application of a flocked~
fiber layer to jacket material;
Figure 2 schematically shows a diskette; and
:'~
'. ~
:' .
.
,. ~;,
. , . -:, .: . . :
'' ' , ' . ,~ . '
--5--
Fi~. 3 is an enlarged cross-section along lines
3--3 of Fig. 2.
Referring to Fig~ 1, jacket material 10 is
unwound from a rol~ and coated with an adhesive
composition at a hopper-fed-knife-coater 12. Fibers 14
fallin~ from a brush hopper 16 are electrostatically
attracted to the adhesive layer 18 with the aid of
electrodes 19. A beater-bar mechanism 20 beneath the
jacket material 10 assists in driving the fibers into the
adhesive layer 18 to provide a flocked-fiber layer 22.
An oven 24 drives of the water from the adhesive to bond
the fibers to the jacket material. A cleaning station 26
removes loose fibers from both surfaces of the finished
material which is then wound up into a roll 28.
The finished material of the roll 28 i5 later
unwound and die cut to provide individual jacket blanks
which are folded around a flexible magnetic recording disk
30 to provide a diskette 32 as seen in Fig. 2. A series
of adhesive dots 34 bond the folded edges to the surface
of the jacket.
Referring to Fig. 3, the jacket of the diskette
32 consists of the jacket material 10 and the
flocked-fiber layer 22 (which includes the adhesive layer
18). The jacket material 10 at one side 35 of the
diskette extends beyond and is folded around the other
side 36 of the diskette and it~ overlapped fiber-flocked
layer 22 is bonded by the adhesive 34 to the uncoated
surface of the underlying jacket material 10. A better
bond has been obtained than has been experienced in
bonding olded edges in the prior art.
Example 1
Opa~ue plastici2ed polyvinyl chloride film of
0.275 mm thickness ~f the type used for flexible diskette
jackets was knife-coated on one face with a water-borne
acrylic-vinyl latex adhesive to a wet thickness of about
0.125 mm which by itsel would dry to a thickness of about
9 ~ ~
~6
0.075 mm. Random-cut cotton flock (14-24 micrometers in
diameter and 0.05 0~4 mm in length) was electrostatically
attracted to the adhesive coating which was tacky and
viscous, and the fibers were embedded into the adhesive
with the aid of beater bars~ After the flocked-fiber
layer coat was dried in an air-circulating oven for 2
minutes at 50C., both surfaces were aggressively brushed
and vacuumed to remove loose fibers, and the finished
material was wound up into a stock roll.
The stock roll was later slit to a useful width,
further cleaned, and then calendered to reduce the overall
thickness of the jacket material with its flocked~fiber
layer to 0.45 mm. Sheets cut from the roll were stacked
and placed in an oven at about 52C. for two hours to
15 remove the roll-induced curl.
The sheets were die-cut to provide blanks which
were folded and the two side flaps were sealed with a
hot-melt adhesive. A magnetic recording disk was
inserted, and the third flap was folded and sealed to
20 provide finished diskettes. The openings in the jackets
appeared to be free from any fibers protruding from the
flocked-fiber layer which could not be delaminated. In
these respects the diskettes of Example 1 appeared to be
superior to any diskette now on the market.
A number of diskettes of Example 1 were tested by
rotating the jacket in the horizontal position while the
disk was pinched between the two sides of the ~acket as in
ANSI Specification No. X3B8/78-145. Diskette users
generally specify ten million rotations without any
30 visible effect upon the magnetic recording disk. Not a
single di.skette of Example 1 has failed this test even
though many specimens have been tested for ten million
rotations and some have been tested for 20 million
rotations~
Initial tests suggest that the diskettes of this
invention are at least equal in performance to all
presently commercially available diskettes as to the
~ ~ 5 5 ~
--7~
torque required and the variability in the torque required
to rotate the disk.
_amples 2-11
Various diskettes of the invention were made as
in Example 1 except for changes indicated in the following
table.
_ Jacket _ Pdhesive
Thickness Thickness
Example Material (mm) Material Wet (mm) Fibers
2 PEr 0.15 A 0.15 nylon
10 3 PET 0.15 E 0.1 rayon I
4 PP 0,25 E 0.1 cotton
PP 0.25 E 0~1 rayon II
6 PC O.25 B 0.125 rayon III
7 PVC 0.275 D 0.1 rayon I
15 8 PVC 0.175 C 0.1 cotton
9 PC 0.25 B 0.125 polyester
~I 0.175 C 0.125 cotton
11 P'II 0.25 C 0.1 cotton
PET = opaque biaxially-oriented polyethylene
terephthalate film
PP = opaque biaxially-oriented low-density polypropylene
film
PC = opaque polycarbonate film
PVC = opaque plasticized polyvinyl chloride film
P-I = calendered manila paper made for tabulating card
us~
P-II = latex-coa ed paper
A = water borne acrylic latex~ A9% solids
B = water-borne acrylic latex, 45~ solids
C = water-borne acrylic latex, 43~ solids
D = water-borne vinyl-acrylic la~ex of Example 1
E = water-borne ethyl acrylate/polyvinyl acetate latex,
5~% solids
9 ~ ~
nylon = randon~cut nylon, 11-19 micrometers in thickness
and 0.25-0~625 mm in leng~h
rayon I = random-cut rayon, 9-17 micrometers in thickness
and 0.25-0.625 mm in length rayon II - precision-cut rayon, 1~ micrometers in thick-
ness and 0.25 mm in length
rayon III = precision-cut rayonJ 12 micrometers in thick-
ness and 0.375 mm in length
cotton - random-cut cotton of Example 10 polyester = precision-cut, cold-drawn polyethylene
terephthalate, 17 micrometers in thickness
and 0.5 mm in length
Of the fibers used in the diskettes of Examples 1-11,
cotton provided the softest fabric and hence caused the
least amount of wear o~ the facing magnetic recording
layer. Rayon provided nearly equal softness. Of the
fibers, the free ends of the cotton had the greatest
tendency to lie in the plane of the surace of ~he fabric
As a consequence, frictional drag was desirably low. Of
the fabrics of Examples 1-11, those made with cotton had
the least directionality and hence provided the least
variability in the torque required to drive the disko The
random-cut rayon was nearly as good as cotton in this
respect. Of the fabrics, those made with rayon best
dissipated static charges, with cotton a close second.
Of the jacket materials, polyvinyl chloride was
the easiest to handle in folding and showed the least
tendency for th~ fold to open upon exposure to elevated
temperatures. However, polyvinyl chloride was the most
susceptible to damage if exposed to unusually high
temperatures which might carelessly be encountered.
