Note: Descriptions are shown in the official language in which they were submitted.
t ~'
~ 94/09497 2 1 4 ~ ~ 1 8 PCT/US93/08288
EPOXY IMPREGNATED TAPE BACKING
Background of the Invention
The present invention relates to backing
materials for tapes comprising flexible substrates which
are either coated or impregnated with polymerizable,
cationically sensitive compositions. Polymerization is
achieved using ionic organometallic compounds as
photoinitiators.
Description of the Related Art
The formation of polymerized, crosslinked structures
using cationically sensitive species is well known. A
variety of methods for polymerizing these species has
been disclosed in the prior art, including the
polymerization of epoxy materials. The earliest reports
of polymerization of epoxy materials relied upon thermal
curing using, e.g., polyfunctional amines or anhydrides.
See, e.g., Industrial Polymers, Ulrich, Hanser Publiching
Co., Copyright 1982, pages 91-94.
Rec~ntly, more convenient means of curing epoxies at
room temperature have been discovered, i.e., photo-
polymerization. These methods rely upon generation of
reactive species which initiate polymerization without
heating. This is accomplished most frequently by using
photoinitiators which react to light at specific
wavelengths. Photoinitiators for cationically sensitive
species reside in three main classes, i.e., aryldiazonium
salts; sulfonium salts, iodonium salts, and related
compounds, commonly called "onium" salts, and
organometallic compounds; see, Photocrosslinking of Epoxy
Resins, Advances in Polymer Science 78, F. Lohse & H.
Zweifel, Springer-Verlag Publ., 1986, pages 61-81.
The use of epoxy resins in tape backings is also
known in the art.
JAP 61197869 discloses the use of compositions
containing a blend of epoxy monomers to permeate a porous
W094/09497 ~ ~ 4 ~f 4.1 ~` PCT/US93/082 ~
-2-
web or substrate. This impregnated web may be cured to a
rigid condition by exposure to an ultraviolet energy
source.
JP58002372 discloses the addition of flame
retardants to provide this desirable characteristic to
cured structures.
U.S. Patent 4,704,322 discloses an epoxy
impregnated, electrically insulating tape having three
layers. An inner layer of mica flakes is sandwiched
between two layers of scrim fabric. The composite
structure is coated with a low viscosity, fluid,
polymerizable, epoxy composition. The epoxy composition
comprises three main ingredients; an epoxy resin, a
phenolic accelerator and an organic titanate. Coating is
accomplished by brush application of the fluid to the
tape. The tape absorbs the fluid thereby becoming
impregnated with the epoxy composition. Application of
heat converts the tape to a B-staged condition. In this
condition the structure is stable under normal storage
conditions. When desired, it is possible to convert the
electrically insulating tape to a rigid, fully cured
condition by the application of heat.
United States patent 5,089,536 discloses the use of
organometallic photoinitiators for cationic
polymerization of a wide range of polymerizable species.
However, it does not address the relative rates of curing
when compared with other types of cationic polymerization
initiators e.g. diazonium or other "onium" catalysts.
Nor does it discuss control of the flexibility of
articles, such as porous web materials, which may be
impregnated with epoxy compositions which are
subsequently cured under the influence of suitable
actinic radiation. This reference also teaches that
solvents are required to provide epoxy compositions of
desired viscosity, which is undesirable.
Also, most prior art backings containing epoxy
monomers are relatively unstable and must be used within
214 4 ~ 1 8 PCT/US93/08288
a short time of addition of a curing agent. They must be
further processed after polymerization, usually by
heating, in order to develop any shelf stability. This
is time consuming, and expensive.
The present inventors have now discovered that
simplification of the process and an increase in the rate
of production of backing materials, as well as backing
materials of prescribed flexibility, can be obtained by
the use of a blend of epoxides in combination with
certain organometallic photoinitiators. The use of
organometallic photoinitiators facilitates the cationic
polymerization reaction more effectively than previously
disclosed cationic polymerization initiators such as
"onium" salts.
Preferred compositions of the current invention are
stable even with the photoinitiators present, until
exposed to suitable actinic radiation. The invention
therefore overcomes problems associated with earlier
backings constructions by eliminating the need for
solvents and providing a faster, less costly method of
manufacture which is free from the time consuming post-
curing procedures at elevated temperatures.
It has further been discovered that, by varying the
coating or impregnating compositions, it is possible to
control the flexibility of the resulting backing
materials.
Summary of the Invention
The invention provides electrical tape backings
useful with various adhesives, having controlled
flexibility, along with the requisite electrical and
handling properties.
Tape backings of the invention comprise a substrate
coated or i~ eyllated with a blend of epoxy materials, at
least one organometallic photoinitiator, and at least one
accelerating agent.
~ ~14~41$
--4--
Specifically, the in~ention provides a tape backing
comprising a substrate which has coated thereon a
photopolymerized epoxy composition containing
a) a plurality of epoxides including at least one
selected from the group consisting of cycloaliphatic
epoxides and bisphenol A epoxides, and at least one
aliphatic epoxide,
b) from 0.1~ to 2% of at least one organometallic
cationic initiator capa~le of initiating
polymerization at wavelengths of from 2~ to 600 nm,
~ 80
and
c) at least one accelerating agent,
wherein said backing is fully cured after an irradiation
of from l to 15 seconds, without a heating step.
Preferred tape backings of the invention comprise a
porous substrate, and are therefore impregnated by the
photopolymerizable epoxy composition.
In one preferred embodiment of the invention using a
polyester substrate, electrical tapes, comprising an
adhesive and a flexible backing therefore are provided,
said backing comprising a substrate having coated
thereon,
a) a photopolymerized polymer containing
a plurality of epoxides including at least one
selected from the group consisting of cycloaliphatic
epoxides and bisphenol A epoxides, and at least one
aliphatic epoxide,
b) at least one organic photoinitiator comprising at
least one catalytically-effective amount of an ionic
salt of an organometallic complex cation sufficient
to effect polymerization, said metal being selected
from elements of Periodic Groups IVB, VB, VIB, VIIB,
and VIII~, and
c) at least one accelerating agent,
wherein said tape has a dielectric strength of at least
3.5 kV to 10 kV, and an insulating resistance of at least
1 x 106 Megaohms. ~
~ 094/0g497 i PCT/US93/08288
21~18
-5-
As used herein these terms have the following
m~A~;ngs.
1. The term "photopolymerizable" means that a
compound or composition is capable of polymerizing when
irradiated by ultraviolet emissions in the range of from
about 180 nm to about 420 nm.
2. The term "impregnated" means that a substrate
contains porosities which have been filled to the
saturation point by the photopolymerizable composition.
3. The term "epoxide" is used to refer to an
individual material containing at least one epoxy group.
The term "epoxy" is used interchangeably, and also used
to refer to a resin containing a blend of epoxides.
Detailed Description of the Invention
Epoxy blends useful in tape backings of the
invention can be aliphatic, cycloaliphatic, aromatic or
heterocyclic and will typically have an epoxy equivalent
of from 1 to 6. Particularly useful are the aliphatic,
cycloaliphatic, and glycidyl ether type 1,2-epoxides such
as propylene oxide, epichlorohydrin, styrene oxide,
vinylcyclohexene dioxide, glycidol, butadiene oxide,
glycidyl methacrylate, and the like.
Representative epoxides include glycidyl ether of
bisphenol A, vinylcyclohexene dioxide, 3,4-
epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate,
3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-
methylcyclohexane carboxylate, bis(3,4-epoxy-6-
methylcyclohexylmethyl)adipate, aliphatic epoxy modified
with polypropylene glycol, dipentene dioxide, epoxidized
polybutadiene, silicone epoxy, 1,4-butAn~iole diglycidyl
ethylene, polyglycidyl ether of phenolformaldehyde
novolak, resorcinol diglycidyl ether, polyglycol
diepoxide, polyacrylate epoxide, urethane modified
epoxide, polyfunctional flexible epoxides, and mixtures
thereof.
21~4~18
.
~; .
Preferred epoxides include 3,4-epoxy cyclohexyl
methyl-3,4-epoxycyclohexane carboxylate, bis(3,4-epoxy
cyclohexyl)adipate, polyglycidyl ether of an aliphatic
polyol, polyglycidyl ether of castor oil, polyglyol
diepoxide and tetrabromo bisphenol A glycidyl ether.
Epoxides of the bisphenol A type, when polymerized
to the resin form, will form a relatively rigid
structure, as will cycloaliphatic epoxides. This may be
modified by the addition of multifunctional aliphatic
epoxides which, on their own, normally provide pliable
cured resin structures. When both types of epoxides are
combined in photocurable compositions it is possible to
produce cured resin systems with properties intermediate
between those of the pure resin systems.
By varying the proportions of cycloaliphatic epoxide
and bisphenol A epoxide to aliphatic epoxide, it is
possible to provide a range of resin flexibilities from
somewhat rigid to quite flexible. These same
characteristics of rigidity or flexibility may be
imparted to flexible substrates which are either coated
with the photocurable compositions or impregnated with
them.
While at least two epoxides are required for control
of flexibility it is possible to add others. The
additional epoxides may provide other attributes beyond
control of flexibility. Such attributes include, e.g.
water repellency, flame retardancy, etc. A brominated
epoxide, based on bis-phenol A, exhibits flame retardant
properties. Some flame retardancy of the brominated bis-
phenol A is conveyed to the composition when it is
included with other combinations of epoxides.
Tape backings of the invention also comprise at
least one catalytically-effective amount of an ionic salt
of an organometallic complex cation sufficient to effect
polymerization, said metal being selected from elements
of Periodic Groups IVB, VB, VIB, VIIB, AND VIII~.
21~418
--7- ~
Specifically, the ionic salts having the formula:
tLI')(L~)(L3')M'] ~LIb)(L~)(L3b)~]h[Ll')(L )(L )~]
~Lld)(L2d)(L3d)~]~(~)(L5)(L6)+ex
wherein M-, Mb, ~, and ~ repr~sent metal atoms which may
be the same of diffe~rnt s lected from the elements of
periodic Groups IVB-VIIIB. The photoinitiator may be a
mononuclear, binuclear, trinuclear or tetranuclear
complex compound comprising the metallic atoms and the
attendant ligands, L.
Ligands are provided by any compound having an
accessible unsaturated group, i.e., an ethylenic group
acetylenic group or aromatic group, which have ~-
electrons regardless of the total molecular weight of the
compound. Such compound must be soluble in a reaction
medium for these electrons to be accessible, see e.g.,
U.S. Patent 5,089,536.
Useful compounds include, but are not limited to,
cyclopentadienyl iron (II) hexafluoroantimonate,
cyclopentadienyl iron (II~ hexafluorophosphonate,
cyclopentadienyl iron (II) hexafluoroarsenate and the
like.
Preferred electrical tape backings of the invention
also comprise an accelerating agent such as a peroxide.
Useful ~eroxides include such as cumene hydroperoxide,
25 ~ ~}~ hydroperoxide, methylethylketone peroxide,
tribut~yl cumene peroxide, and triphenyl methyl
hydroperoxide.
Useful accelerating agents provide a cured resin
which is dry to the touch and therefore will not block
when converted into ro'l form. Unless the accelerator is
- present, it is freguently necessary to promote complete
curing of the epoxy compositions of this invention
- usually by heating.
Preferred electrical tape backings of the invention
also comprise at least one flame retardant. This may be
a brominated ether of bisphenol A, as discussed abo~e, or
2144418
.. . . . .
may be an inorganic flame retardant additive, such as
various metal oxides and oxide hydrates, as well as
nitrogen or phosphorous containing compounds. Preferred
flame retardants include, but are not limited to, oxides
of antimony in combination with brominated bisphenol A
epoxides.
Compositions of the invention may also include
optional adjuvants such as co-curatives, hardeners,
fillers, plasticizers, pigments, antioxidants, surface
modifying agents, and the like in amounts such that they
do not interfere with the photopolymerization of the
epoxides.
Useful substrates for the invention include porous
substrates such as glass cloth; papers such as flat back
paper, and crepe paper; nonwovens, such as polyester, and
cellulose~r~acetate~ Also useful, though less preferred
are nonporous substrates, including film-forming
polymers, e.g., polyesters, acetates, polyphen~iene
sulfide, polyimide, and the like.
Tape backings of the invention are made by mixing
the epoxides with the photoinitiator, and then coating
the photopolymerizable mixture onto a desired substrate
and photopolymerizing to a dry state.
The photopolymerization, or curing reaction, for the
composites of the invention, will proceed at a faster
rate than for compositions lacking the organometallic
photoinitiator. When desired, the composite is then
fully cured, i.e., irradiated, by exposure to an
ultraviolet light having emissions in the range of from
about 180 nm to about 420 nm.
Materials of this invention are useful as adhesive
tapes, electrical tapes or rigid insulating composite
str~ctures.
Depending on the use desired, one skilled in the art
can easily select an adhesive for use with the tape
backings of the invention. Useful adhesives include, but
are not limited to, rubber resin adhesives, synthetic
094/09497 2 1 4 4 ~ 1 8 PcT/us93/o8288
g
block copolymers such as styrene-butadiene-styrene,
polybutadiene, polyisoprene, styrene-isoprene copolymers,
acrylate adhesives such as those disclosed in RE 24,905,
and blends of the above, all of which may include
tackifiers and other conventional additives. The
adhesives may be hot-melt, solution polymerizable,
suspension polymerizable, or preferably, ultraviolet
radiation polymerizable, such as those disclosed in U.S.
Patent 4,181,752.
When an electrical tape is desired, the tape should
have a dielectric strength of at least 3.5 kV to 10 kV,
an insulating resistance of at least 1 x 106 Megaohms.
The adhesive may also contain a flame retardant additive
such as those described, infra, as useful in the tape
backing.
Useful tapes of the invention are made by coating an
adhesive mass onto the tape backing by conventional
coating methods such as knife coating, gravure coating,
meyer bar and the like, and then curing the adhesive by
the appropriate means.
Test Methods
Adhesion Test
A strip of adhesive tape (2.54 cm x 25.4 cm) is
applied with adhesive contact to the cleaned and polished
surface of a Type 302 steel plate (5 cm x 12.2 cm x 0.16
cm). Constant pressure is applied to the tape strip by
slowly rolling a 2 kg rubber coated steel roller two
passes over the plate at a speed of 5 cm/sec.
Approximately 12.2 cm of tape extends beyond one end of
the steel plate. The adhesive tape is then conditioned
for 20 mins. Adhesion measurement requires that the
steel plate is positioned with its length vertically
disposed. The tape extension hangs from the lower edge of
the plate. The end of the tape extension, farthest away
from the steel plate, is folded to cause adhesive-to-
adhesive contact and form a tab of approximately 2.54 cm
W094/09497 2 ~ 4 ~ ~ ~ 8 PCT/US93/0828 ~
--10--
long. By grasping this tab and lifting vertically, a U-
shaped loop, with adhesive on the outer face of the U,
may be formed. Further application of force produces
tension in the tape loop and causes the tape to separate
or peel back from the steel plate. When approximately
1.27 cm of tape has peeled back, the lower end of the
steel plate is centrally clamped in the lower jaw of a
tensile testing machine, i.e., INSTRON~ Model TM. The
2.54 cm tab is clamped in the upper jaw of the tester.
The lower jaw is held in a fixed position while the upper
jaw is raised at a speed of 30.5 cm/min.
The average force registered during removal of the
tape from the steel plate provides the measure of
adhesion to steel.
Two-Bond Adhesion
A 2.54 cm x 12.7 cm strip of double-coated adhesive
test tape on a release liner is placed lengthwise,
located centrally along a cleaned steel panel (5.1 cm x
12.7 cm x 0.13 cm). The unprotected adhesive coating is
used for attachment to the steel plate. The steel panel
is placed on a flat surface with the test tape visible on
the upper surface of the plate. A 2 kg rubber coated
roller is used to apply constant pressure to the tape by
rolling along the release liner for several passes.
A single-coated specimen tape (2.54 cm x 12.7 cm),
which is subject to property measurement, is prepared for
attachment to the test tape. The opposite side of the
backing is wiped with a degreasing solvent, and then the
release liner is removed from the test tape. The
cpecimen tape is applied lengthwise so that the degreased
side is in contact with the newly exposed adhesive
surface of the test tape. 7.62 cm strips of a single
sided, aggressive adhesive, tape are placed across the
width of each end of the steel panel and the specimen
tape to hold it in position. An additional strip 30.5 cm
long x 1.27 cm wide is placed lengthwise in adhesive-to-
094/09497 2 ~ 8 PCT/US93/08288
adhesive contact such that approximately 15 cm of theaggressive adhesive tape extends beyond one end of the
steel panel. Since the specimen tape is wider than the
aggressive adhesive tape, exposed fields of adhesive
extend on either side of the latter. These adhesive
fields are protected by adhesive-to-adhesive application
of strips (12.7 cm long x 1.27 cm wide) of the aggressive
adhesive tape. The resulting layered tape structure is
compressed with several passes of the 2 kg roller in
either direction.
The steel panel is placed with its longitudinal axis
in a vertical orientation with the aggressive tape
extension hanging from its lower end. The end of the
tape, furthest from the plate, is folded back in adhesive
contact with itself to form an end tab approximately 1.27
cm long. By grasping this tab and lifting vertically, a U
shaped loop is formed with adhesive on the outer face of
the U. Further application of force produces tension in
the tape loop and causes the aggressive adhesive tape to
urge 100% removal of adhesive from the specimen tape.
Application of this force is maintained until the tapes
are separated for a distance of approximately 2.54 cm.
At this point the lower edge of the steel panel is placed
in the lower jaw of a tensile testing machine, i.e.,
INSTRON~ Model TM, and the tab of the tape loop is placed
in the upper jaws of this tester.
The force required for separating the specimen and
aggressive adhesive tapes for an additional distance of 5
cm is measured as the lower jaw of the test machine is
withdrawn relative to the fixed upper jaw.
Tensile and Elonqation Tests
Tensile at Break - The stretching force, per unit
width, at which a linear test sample fails and ruptures
into two distinctly separate portions.
Elonqation - Comparison of the increase in length of
W094/09497 ii4 ~ 4 1 8 -12- PCT/US93/0828
a stretched versus an unstretched test sample at the
instant that the sample breaks under the applied
stretching force.
A sample of backing material 17.8 cm long x 2.54 cm
wide is placed between the jaws of an Instron~ TM tensile
tester with the longitudinal axis in a vertical
orientation such that one end of the sample may be
clamped in the upper jaw of the tensile tester and the
opposite end of the sample in the lower jaw of the
tester.
The test is run by separating the jaws of the tester
at 30.5 cm per minute. As the sample stretches, the force
applied is increased to a level at which failure and
rupture occurs in the central portion of the sample.
Measurement of tensile is obtained by determining the
maximum force per unit width just before failure.
Elongation is measured as the percent increase in length
of the sample, under maximum load, before failure.
Roll Unwind Test
A roll of adhesive tape of the invention having a
width of 2.54 cm is wound on to 7.62 cm ID cores and
limited in length so that the roll diameter does not
exceed 16.5 cm. Using a modified tensile tester, Thwing-
Albert, Intelect 500 TA, the force to unwind a roll of
this tape is measured as follows.
Initially, five laps of tape are unwound from the
adhesive roll and ~isc~rded. The roll of tape is then
placed over an unwind mandrel which is of a size to
accommodate the 7.62 cm core, located on the front of the
tensile tester. A length of tape is unwound and
adhesively attached to a drive roller. The longitudinal
axes of unwind mandrel and drive roller are parallel and
they are positioned at approximately the same height.
Between the unwind mandrel and the drive roller, the tape
adopts the form of an inverted U, the apex of which is
supported on but not in adhesive contact with the surface
094/09497 2 1 ~ PCT/US93/08288
~ .... f
-13-
of a freely rotating cylinder. This cylinder is attached
to the load cell of the tensile tester, and has a
diameter similar to that of the adhesive tape roll. The
freely rotating cylinder is positioned above, midway
between and in the same vertical plane as the unwind
mandrel and the drive roller. With the drive roller in
motion, the tape is pulled from the roll of adhesive
tape. The force, generated during unwind, between
adhesive and backing, is transmitted to the rotating
cylinder and thence to the force sensing load cell.
During smooth operation of the drive roller (1.27 m/min)
over a pre-selected cycle time the force transmitted to
the load cell is measured and converted to a number for
tape unwind.
Dielectric Breakdown Determination
A specimen 15.25 cm in length x 2.54 cm in width is
cut from a roll of tape, and one end is inserted between
the electrodes of a dielectric tester, e.g., one capable
of increasing voltage at a uniform rate of 0.5 kv/sec,
with the adhesive surface contacting the upper electrode.
The voltage control, Variac, is then zeroed, and the
circuit breaker is reset. The tester is then initialized
such that the voltage potential across the specimen will
increase until the flow trips the circuit breaker. The
voltage at which the dielectric breakdown occurs is then
recorded. The procedure is repeated at the opposite end
of the specimen and at the center. The average of the
three individual breakdown voltages is then recorded.
Insulative Resistance Measurement
This test requires 12 polished stainless steel
electrodes 0.64 cm x 0.64 cm x 2.54 cm with rounded edges
mounted on a solvent cleaned methylmethacrylate test
board 2.54 cm apart. (For further information on the test
W094/09497 PCT/US93/08288 -
- 21~18
-14-
board, see ASTM D-1000). Several outer wraps are
discarded from a roll of tape, and a 23 cm sample is cut.
This sample should be handled carefully so that the inner
two-thirds is not touched. The sample is placed adhesive
side down on top of six cleaned electrodes, and a second
set of electrodes and retaining clips are placed thereon
to form a sandwich. Any excess sample is then cut off,
and the test board is placed on a test chamber capable of
maintaining 96% relative humidity at 23C. with the
adhesive toward a glycerine solution having refractive
index of 1.336-1.34. Condition the specimen for 18 hours
at 23C and 50% RH. Attach a megometer to the test
board, and set at 120V. Measure insulation resistance
across each pair of electrode terminals (total 5
readings). Record the average insulation resistance in
megaohms.
FlammabilitY
The flammability test involves wrapping a film strip
around a wire with a 50% overlap and repeating with
another film strip in the opposite direction. The
wrapped wire is exposed to an open flame for 30 seconds.
The flame is removed and the burn time of the film is
measured. Desirable flame retardance would be exhibited
by a material that does not begin to burn, or self
extinguishes in less than 4 seconds.
The following examples are meant to be illustrative,
and are not intended to limit the invention. Persons
skilled in the art will easily discern variations within
the scope of the invention, which is defined by the
claims.
Exam~les
Exam~le 1
A three necked, round bottom flask having a stirrer
and thermometer was charged with 60.0 gm bis(3,4-
epoxycyclohexyl)adipate, available as "ERL 4299", from
2 1 ~ 8 . ~;
-15-
Union Carbide Inc., and 40 gm polyglycidyl ether of an
aliphatic polyol, available as "Heloxy 84", from Rhone
Poulenc. This mixture was stirred while being heated to
75OC, and then maintained at this temperature. The
photoinitiator, 1.0 gm cyclopentadienyl iron (II)
hexafluoroantimonate, was added to the flask. Stirring
of the contents continued for one hour with the
temperature controlled at 75C. The hot fluid
composition was filtered, and allowed to cool to room
temperature. Just prior to coating, 1.5 gm cumene
hydroperoxide, available from Atochem, was adde,d. The
coating composition had a viscosity of <~ c~s. It was
applied to a substrate of glass-cloth, "Burlington Glass
Fabric - Style I8026". The fluid composition was
absorbed by the glass cloth, impregnating the whole
structure with epoxy fluid. The impregnated ~lass cloth
was subjected to ultraviolet rays in the range of 180 -
420nm, for a period of <10 secs using an American ~V
Company mini-conveyorized curing system, having variable
lamp intensity and speed control. The resulting backing
material was tested to determine its tensile, elongation
and electrical insulation characteristics. These values
are shown in Table l.
Table 1
Insulation Tensile Elongation
Resistance (ohms)kg/cm2 percent
3 x 10l~ 13.26 5.4
This glass cloth backing material was further coated with
a rubber based adhesive. This adhesive tape is useful
for applications where tape is used for electrical
insulation. Measurements, from this tape, of adhesion to
steel and unwind are shown in Table 2.
Table 2
Adhesion to Steel Roll Unwind
N/dm gms/cm
Glass C'oth Backing 16.6 248.4
094/09497 2 1 4 ~ PCT/US93/0~288
ExamPles 2-3
The epoxy fluid of example 1 was coated separately
on crepe paper, available as "M-2251" from Mosinee Paper
Corporation, Mosinee Wisconsin, and flat-back paper,
available as "#525" from Lydell, Inc., Troy, N.Y.
Insulation resistance, tensile and elongation for these
were tested as described above, the results are shown in
Table 3.
Table 3
Insulation Tensile Elongation
Resistance (ohms) kg/c*percent
Crepe Paper 5 x 10l3 16.65 7.9
Flatback Paper 8 x lol 2.3 13.9
These backings were also coated with rubber based
adhesives, and tested for adhesion and roll unwind. The
results are shown in Table 4.
Table 4
Adhesion to Steel Roll Unwind
N/dm gms/cm
Crepe Paper 23.9 173
Flatback Paper 28.3 215
Example 4
A flame retardant backing of this invention was
prepared by including a flame retardant polymer and a
flame retardant pigment in the coating composition.
The composition contained 40.0 gms "ERL 4299", 30.0
gms "Heloxy 84", 30.0 gms Tetrabromo Bisphenol A
Diglycidyl Ether, available as Epirez 5163, from Rhone
Poulenc, 4.0 gms ultrafine grade antimony trioxide,
available from Laurel Industries, 1.0 gm photoinitiator
and 1.4 gms cumene hydroperoxide. This composition was
applied to a non-woven polyester substrate and subjected
~ A~J~
2 1 4 4 4 1 8 Pcr/usg3/08288
-17-
to 180 nm to 420 nm radiation from an ultraviolet light
source.
The resulting backing material was tested using UL~
(Underwriters Laboratory), 510 flame test. An average
time of 14 seconds was required to extinguish the flame.
.
~Amples 5 and SC
The following coating compositions were prepared as
in example l, except that the photoinitiator was varied.
Example 5 Example 5C
ERL 4299 40.Ogm 40.Ogm
Heloxy 84 30.Ogm 30.Ogm
Bpirez 5163 30.Ogm 30.Ogm
Antimony Trioxide 4.Ogm 4.Ogm
15 Photoinitiator l.Ogm~ 3~0gm2
Cumene Hydroperoxide l.Ogm O.Ogm
I Cyclopentadienyliron(II)xylene hexafluoroantimonate
2 FX 512 - a sulfonium hexafluoroantimonate
Using continuous coating, exposing and wind-up
equipment, examples 5 and 5C were applied separately to
samples of non-woven polyester substrate material. The
epoxy coated web was transported at 180 cm/min past a W
light station, which emitted radiation in the range of
180nm to 420nm at an intensity of 200 watts/in. Example
5, a composition of the present invention, provided a
fully cured backing which was dry to the touch.
Conversely, Example 5C, a composition outside the scope
of the invention, did not cure fully and remained tacky.
The web speed was then reduced to half the original
speed, i.e., 90 cm/min, with the lamp conditions
` unchanged. Example 5C failed to cure completely; Example
5 was fully cured. This demonstrates that compositions
of the present invention cure more rapidly than those
using catalysts of the "onium" type which have been
reported previously. The backings were aged at 100C for
10 minutes, to completely cure Example 5C, then coated
W~94/09497 2 1 4 ~ 4 1 8 PCT/US93/0828 ~
-18-
with rubber adhesive, as described in Example 1, and
tested for tensile and elongation. The results are shown
in Table 5.
Table 5
Tensile StrengthElongation
N/dm percent
Example 5 578 26.00
Example 5C 394 35.50
~ - !
1 8
~ , . ~ .
--19--
- ExamPles 6-9
These example5 were made according to example 1
except that the epoxy ratios were varied as indicated in
Table 6.
s These backings were coated with a tacXfied natural
rubber adhesive and an isooctyl acrylate/acrylic
acid/methyl acrylate adhesive (7 and 8), and tested for
adhesion, tensile and elongation, and flammability. The
results are shown in Table 6.
Table 6
EXAMPLE NUMBER
COMPOSITION 6 7 3 9
ERL 4299 - Epoxy 70 60 50 40
15Epirez 5163 - Flame 30 30 30 30
Retardant
Heloxy 84 - Epoxy O 10 20 30
Photoinitiator~ 1 1 1 1
Cumene HydroperoXide 1.5 1.5 1.5 1.5
20Antimony Trioxide 4 4 4 4
Tensile (kglcm2) 2.4 2.3 2.4 2.3
Elongation (Percent) 4 13 25 25
2-Bond Adhesion tN/dm) 133 133 140 lll
(105*) (106*)
25Adhesion (N/dm) 43 46 43 39
(49*) (49*)
Dielectric ~ ~nt 5.1 4.9 4.7 5.0
(kV) (4 3*) (5 7*)
Insulation 1.2x10l3 2.9x10~2 3.3xlO~ 2.0x10l
Resistance(Ohms)
30Thickness (~m) 135 127.5 127.5 130
Fl~mm~hility (secs) 13 23 34 <20
' Cyclopentadienyliron (II) xylene hexafluoroantimonate
* Asterisked values were obtained from tape constructions
having an acrylate adhesive.
