Note: Descriptions are shown in the official language in which they were submitted.
2~636
-1- 557-2797
FILM FOR THERMAL IMAGING
BACKGROUND OF THE INVENTION
This invention relates to thermally image able films,
and to a release coating for such films.
Infrared imaging is a form of thermal imaging that
involves the use of a focused infrared lamp to heat an infrared
absorbing image, commonly referred to as the "original", which
image is in contact with a substrate, e.g., a transparent polymeric
film, having thermally sensitive imaging chemicals applied to a
major surface thereof. Upon image-wise absorbing the focused
infrared radiation, the original transfers the absorbed heat to the
thermally sensitive imaging chemicals on the surface of the sub-
striate, thereby causing a chemical reaction which results in the
formation of a copy of the image of the original on the substrate.
It is frequently desirable to prepare projection trays-
pernicious, e.g. transparencies for overhead projectors, from
originals which are actually plain paper copies that have previously
been prepared from electrophotographic imaging processes. The
electrostatic latent image on such a plain paper copy is developed
I by the application and fixing of toner powder to the plain paper
copy. Toner powder is generally a blend of polymer having low
melting point, and carbon. When the toner on the surface of a
plain paper copy in contact with the substrate from which the
projection transparency is to be prepared absorbs infrared radian
lion, partial remelting of the toner powder on the copy is likely
to occur. The portions of the original which bear the remelted
toner powder will frequently adhere to the transparency. When
the original is separated from -the transparency, toner powder from
.~....,.
I ho
~2~7~i36
-2- 557-2797
the original is likely to be removed from said original and
simultaneously transferred to the surface of the thus-formed
projection transparency. This transfer of toner powder reduces
the optical density of the image on the original and may, in effect,
destroy the quality of the image. Thus, the original can be
damaged when a projection transparency is made from it. The
adherence of the toner powder to the projection transparency may
also result in undesirable effects on the surface of the trays-
patency itself. When the image formed on the surface of the
transparency is black, the toner powder does not harm the image
itself, but the powder may be rubbed off the transparency and
transfer to surfaces which subsequently come in contact with the
transparency. When the image formed on the transparency is a color,
the toner powder can cause the colored image to have irregular black
spots in the colored image area. This is considered to be a major
defect in the transparency. A barrier film interposed between
the image able layer of the transparency and the original can pro-
vent toner powder from being picked up and retained by the trays-
patency. In a type of color transparency currently in use, a film
containing an acid does serve as such a barrier.
In addition to the foregoing problems, certain image able
materials tend to liberate moisture upon exposure to heat or infer-
red radiation. This moisture liberation results in formation of
opaque areas, i.e. "halos", around the edges of the images. These
areas scatter light and project as darkness around the image.
It, et at, U.S. Patent No. 3,955,035 discloses a in-
alkoxy Solon coating which imparts abrasion resistance, hardness,
and release properties to plastics. This coating, however, is
, I.
I.
-pa- 2 I 6 557-2797
brittle and will crack if applied to a flexible polyester sub-
striate of the type commonly used for preparing transparencies.
Clark, U.S. Patent No. 3,986,997 discloses a coating formed from
a dispersion of colloidal silica in a condensate of methyl in-
hydroxy Solon. This
I..
~227~i36
-- 3
coating is also brittle, and, thus, it is unsuitable for flexible
sheeting. Bane, et at, United States Patent No. 4,223,072 disk
closes a coating formed of phenol trihydroxy Solon. Although
this coating exhibits flexibility superior to that of the coating
disclosed in the Clark patent, the flexibility is insufficient to
allow coating on thin polyester films. Grenoble, United States
Patent No. 4,071,644 discloses a flexible sheet material coated
with selections which is useful as a non-adherent surface. The
coating composition in this patent comprises vinyl alkyd selection
oligamers, alkyd hydrogen selections, and a catalyst. These coat-
ins are curable at 250F (121C), a temperature at which a them-
portray sensitive coating such as that required for infrared
image able films and thermally image able films would react pro-
maturely. Garden, et at, United States Patent 3,936,581 discloses
a release coating containing vinyl selections in mixture with
alkyd hydrogen selections and a platinum catalyst. The optimum cure
temperatures are in excess of 100C, a temperature which would
bring about premature reaction of the temperature sensitive coat-
ins of infrared image able films.
According to the present invention there is provided a
film which can be imaged by thermal energy comprising:
(a) a substrate,
(b) a layer of thermally image able material coated on at
least one major surface of said substrate,
(c) a cured organopolysiloxane release coating, capable of
releasing toner, coated over said layer of image able material,
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said release coating being formed from a curable composition come
prosing a mixture of selections consisting essential of from 0.1
to I by weight of methylhydrogenpolysiloxane and from 97 to 99.9
by weight of a selection of the formula
(Shucks - x
in which x has a value from 1.9 to 2 inclusive and in which silo-
Jane substantially all of the molecules have attached thereto at
least a total of two silicon-bonded hydroxyl groups or alkoxy
groups of less than 5 carbon atoms, a catalyst, and a cross-linking
agent, said curable composition being curable at a temperature
under 70C. with a curing exposure time of under 3 minutes.
The preferred release coating is prepared from a compost-
lion comprising (1) a curable polysiloxane, (2) a catalyst, to)
a cross-linking agent, (4) a fast-cure additive, and (5) an
anchorage additive.
I ~2~63~ 557-2797
The release coating composition can be applied to the
imaging film by conventional means and cured at temperatures
sufficiently low so as to prevent adverse effects upon the layer
of image able material. The release coating is also sufficiently
permeable so as to allow moisture to escape from the image able
layer, thereby reducing the "halo" effect. In addition, the
coating is sufficiently flexible so that the film bearing it can be
imaged in commercially available infrared copying machines, e.g.,
EM Model 45 infrared copier. Toner powder from pie n paper copies
will not stick to this coating when the imaging film is processed
in a conventional thermal imaging apparatus, e.g., an infrared
copier.
DETAILED DESCRIPTION
The type of film contemplated for use in the present
invention is any imaging film which can be imaged by being exposed
to thermal energy, e.g. infrared radiation, while in surface-to-
surface contact with an original.
A particularly appropriate type of thermally image able
film contemplated for use in the present invention is described in
Isbrandt, et at, U.S. Patent No. 4,423,139. This film can be
imaged by means of infrared radiation. This film comprises a
polymeric film substrate transparent to visible light, bearing an
image able layer on at least one surface thereof. Substrate
materials which are suitable for this invention include polycarbon-
ales, polyesters, polyacrylates, polystyrene, and polypropylene.
A preferred substrate is polyvinylidene chloride primed polyester
film. The preferred polyester is polyethylene terephthalate.
I 22~763~
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The image able layer comprises a nitrate salt, e.g.,
nickel nitrate, at least one Luke dye, e.g., 3,7-di(N,N-diethyl-
amino)l0-benzoyl phenoxazine, and a binder, e.g., cellulose acetate
bitterroot, one or more aromatic compounds which form quinines,
dominoes, or quinonimes upon oxidation, e.g., catcall, and
l-phenyl-3-pyrazolidinone or derivatives thereof. The layer can
also contain a material which supplies hydrogen ions, e.g., an
acidic material such as phthalic acid. Upon the application of a
sufficient amount of thermal energy, the nitrate salt will oxidize
the Luke dye, resulting in a change in color.
Other thermally image able films that are suitable for use
in the present invention are described in Owen, U.S. Patent No.
2,910,277; Grant, U.S. Patent No. 3,080,254; and Newman et at,
U.S. Patent No. 3,682,684. Owen describes a heat-sensitive
chemically reactive eopy-sheet comprising a thin flexible carrier
web coated with a visibly heat-sensitive coating comprising (1) a
film-forming binder, (2) a noble metal salt of an organic acid,
and (3) a eyelid organic reducing agent for the noble metal ions,
having an active hydrogen atom attached to an atom which is select
ted from the class of oxygen, nitrogen and carbon atoms and is dir-
wetly attached to an atom of the cyclic ring. Grant describes
a heat-sensitive copy sheet comprising the same ingredients as
contained in Owen and further including a sufficient amount of
phthalazine to cause observable darkening of the thermographic
image. In both Owen and Grant, the preferred film-forming binder is
polystyrene resin, the preferred noble metal salts of organic
acid are silver Bennett and silver Stewart, and the preferred
reducing agents are 3,4-dihydroxybenzoie acid and methyl gullet.
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Newman et at describes a heat-sensitive sheet material including
a thin visibly heat-sensitive layer having wide exposure latitude
and comprising a mixture of ferris and silver soaps of long chain
fatty acids, a toner for the silver image, and a finlike kirk-
lent for the soaps. An example of ferris and silver soap mixture
is ferris surety and silver Bennett. An example of a toner
is phthalazinone, and
.
examples of finlike co-reactants for the soaps are pyrogallic acid, catcall,
3,4-dihydroxybenzoic acid, methyl gullet, and Bunnell pyrogallol.
Compositions for preparing the organopolysiloxane coatings suitable for
the present invention must be curable at -temperatures under 70~C with an exposure
time of under 3 minutes. Longer cure times or higher curing temperatures or both
would be detrimental to the imaging chemistry of the thermal imaging system.
Organopolysiloxanes suitable for the present invention include hydroxy-
terminated or alkoxy-terminated polyalkylsiloxanes, for example, organopolysilox-
aye obtained by curing a mixture of selections consisting essentially of from .1
to 3% by weight of methylhydrogenpolysiloxane and from 97 to 99.9% by weight of a
selection of the formula
(CH3)xsiO4-x
in which x has a value from 1.9 to 2 inclusive and in which selection substantial
fly all of the molecules have attached there-to at least a total of two silicon-
bonded hydroxyl groups and/or alkoxy groups of less than 5 carbon atoms, as desk
cried in United States Patent No. 3,061,567; cured epoxypolysiloxanes and their
blends with epoxy-terminated sullenness, as disclosed in United States Patent No.
4,313,988.
Organopolysiloxanes of the type disclosed in United States Patent No.
3,061,567 can be prepared from compositions comprising if) a silicone resin, (2)
a catalyst, (3) a cross-linking agent, and, optionally, a fast-cure additive, and
an anchorage additive.
A commercially available silicone resin which has been found -to be use-
fur for this invention is Sulfa* 294, which is available from Dow Corning
Corporation.
* Trademark
--6--
I ~2276~ 557-2797
Catalysts are desirable for reducing the time required
and heat input necessary to cure the aforementioned silicone
resins. Catalysts useful in the practice of this invention include
dialkyltin salts, wherein the alkyd groups contain from 1 to 6
carbon atoms. Catalysts that are preferred are represented by
the following general formula:
1l
(C4Hg)2Sn(OCR)2
wherein R is -CH(C2H5)(CH2)3CH3, SHEA, 2 10 3
Commercially available catalysts which have been
found to be useful in the practice of this invention include Dow
Conning AYE and Dow Corning ZOO, both of which are avail-
able from Dow Corning Corporation, dibutyltin diacetate available
from Alga Products, and dibutyltin dilaurate, available from Alga
Products and MOB Reagents.
Cross-linking agents can advantageously be employed
for promoting cure. Cross-linking agents suitable for the alone-
mentioned silicone resins include ortho-silicates, for example,
tetramethoxyethoxyethylsilicate.
Commercially available cross-linking agents which have
been found to be useful in the practice of this invention include
Dow Corning C4-2117, available from Dow Corning Corporation,
tetraethoxysilane, available from Alga Products, tetrapropoxysilane,
available from PER Research Chemicals. Dow Corning C4-2117 has
the following formula:
Si~o-cH2-cH2-ocH2cH2-ocH3)4
I;'
I, .
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An anchorage additive can also be added to the sift-
cone resin-containing composition to improve the adhesion ox the
coating to the substrate. A commercially available anchorage
additive is Sulfa 297, available from Dow Corning Corporation.
This additive also is useful
it
27~i3~j
for lncreasillg the pot life of the catalyzed coating
composition formulation. Other pot-life extenders include
an hydrous alcohols, kittens, and acetic acid. Represent
native examples of anilydrous alcohols are methanol,
5 ethanol, and isopropanol. Representative examples of
j kittens are methyl ethyl kitten and methyl isopropyl
j Isetone.
Sulfa 297 has the following formula:
O
11
OKAY
/ 11
R --S i-o SHEA
OUCH
wherein Al is a long chain molecule ending in C-C
or COCK
Preferably I contains from 1 to 5 carbon atoms.
Ike concentration of each ingredient can vary,
the particular amount of each depending upon the combine-
lion of properties needed, as explained hereinafter.
When employing Sulfa 294 resin, it is
preferred that the resin be dissolved in an aliphatic or
aromatic solvent, such as, for example, Hutton, VIM & P
naphtha, Tulane, and blends of Tulane and Hutton. Some
surfaces such as polyethylene may call or high levels of
aliphatic solvents to obtain uniform wetting. It is
preferred that the coa~incJ composition formulation,
hereinafter alternatively referred to as coating bath,
con Eerily 2 Jo 10 percent by wow silicone. The level
of catalyst can vary, depending upon the curing temperature
and time desired. When Dow Corning AYE catalyst is used
with Sulfa 294 resin, it is preferred that the
concentration of catalyst be Eroln 10 to 30 percent by
weight more preferably Lo to 18 percent by weicJht, based
it (-u JOY sulkily cellulose; Wylie Low CornincJ~ ZOO
catalyst is wised with Swahili') 2'~1 resin, it is preferred
- ~276~
that 5 to 15 percent by sleight catalyst, based on weight of
sulkier solids, be employed. When accelerated cure is
desired, Dow Corning C4-2117 fast cure additive can be
used at a level of 5 to 20 percent by weight, preferably 8
to 17 percent by weight, based on weight of silicone
solids. If Dow Corning C4-2117 fast cure additive is
used, either 3 to 8 percent by weight, based on weight of
silicone solids, of Sulfa 297 anchorage additive or 1 to
i 5 percent by weight an hydrous alcohol, based on weight ox
total coating solution, should be used as a pot life
extender.
The ingredients err preparing the curable
silicone poller composition can be combined by introducing
them into a vessel, and mixing them by any suitable mulled,
such as, for example, stirring. Because of possible too
rapid reaction of East-cure additive, e.g. Dow Corning
C4-2117, with catalyst, e.g. Dow Corning ZOO, the
asker a~clitive ~lloulcl lo doled and mixed well before
addition of catalyst.
The composition can be applied to the surface of
the imaging film by any of the techniques known in the art,
such as, for example, knife coating, Mayer rod coating,
curtain coaxing, extrusion bar coating, and rotogravure
coating. The composition is coated over the surface of tile
film bearing the image able layer formulation, thus acting
as a top coat. The composition is preferably applied to
the surface of the imaging film by coating from an organic
solvent. However, solvent less coating is an acceptable
method when using the squeeze roll coating technique.
3 Catalyst and cross-linking agents are critical in
that proper selection thereof will permit coating by means
of efficient methods, such as, for example rotogravure and-
reverse roll.
Phthalic acid and catcall present in the imaging
chelnistry tend to inhibit Lowe cut of the release coating
rally, a Long airy time Lo Nile imaging chemistry allows
for adequate cure, lout a short dry Tony for that layer
l I- 12~76~
reduces the likelihood of adequate cure. The additives
employed with the formulation for preparing the release
coating help to promote a faster cure and improved
anchorage.
i 5 Epoxysiloxane polymers of the type disclosed in
U.S. Patent No. 4,313,988 are represented by the formula,
R2 I R2
Messiah Sue no.
R2 R3 E
wherein R2 is a lower alkyd group of one to three carton
atoms, R3 is a monovalent hydrocarbon radical of 4 to 20
carbon atoms, E is a monovalent epoxy-containing
hydrocarbon radical, M is a sill group R2Si , R2R3Si -
or Russ , where R2, R3, and E are defined above, a is 5
to 200, b is 0 or up to 20~ of a, Ahab is 5 to 200, c may be
0 when Jo is Russ or greater than 0 but less than 20~ of
the value of a Ahab) when M is R2Si , R2R3Si or
Russ and n is 1 to 75. In the above formula, the
preferred R group is methyl, and the preferred M group is
Russ - when c is 0, and R2Si when c is greater than 0.
Also, when c is 0 and M is l~2~Si , n is 1 to 5, and
preferably n is 1 or 2.
The preferred b is 0.
Illustrative examples of the monovalent
hydrocarbon radical, R3, in the above formula are alkyd
radicals such as bottle, isobutyl, tert-butyl, Huxley, octal
and oc~adecyl; aureole radicals such as phenol, naphthyl and
- bisphenylyl; alkaryl radicals such as toll and xylyl;
aralkyl radicals such as phenylmethyl, phenylpropyl and
uhenylhexyl; and cycloaliphatic radicals such as
cyclopentyl, cyclohexyl and ~-cyclohexylpropyl; and ether
3 oxygen- or ester oxyc3en-containillc3 radicals such as
ethoxyuropyl, butoxyhutyl, and etiloxycarbonyluropy:L and the
l lice. 'Lowe prel~erLed [c3 is a Lky.l of Do carbon atoms.
~z2~63~
The selection grouts,
R2 R2 R2
! -so-, -I to-, and -lo-, are
R2 R3 E
ordered or randomly arranged in tile epoxypolysiloxane and
the l~onovalen~ epoxy-containinc~ hydrocarbon radical, E,
kennels a least one polymeri~able epoxy group.
I of _
the remainder being composed ox carbon and hydrogen, free
Ox acetylenic unsatura1ion and in addition Jo the oxen
oxygen can contain ether, o , or carbonyl oxygen, e.g.,
o
--OX--.
Illustrative examples of E are;
-CH2CH2 ~CHCH2 1
-CH(CH3)C O
-Cll2CH2CH20CH2CHCH20 [ire,, gamma-glycidoxyproQyl]
15 -CH2CH2 it beta-(3,4-epoxycyelohexyl)ethyl]
I
-CH,''H~CH3) Ho
-Cl-12C~2C~12 ~OCH2C~IC~
-12- ~27~3~
.
In the above epoxy-containing hydrocarbon
radical, the epoxy group is preferably located at the
terminal position of the radical, but it need not be a
terminal group.
Epoxy-terminated sullenness can be used optionally
with the epoxypolysiloxanes in the coating formulation of
this invention. Use of such epoxy-terminated sullenness
enables the release performance of the coating to be
varied. These epoxy-terminated sullenness are compounds or
Interlace having polymerizable epoxy group(s) and a
polymerizable Solon group, the bridging of these groups
being through a non-hydrolyzable aliphatic, aromatic or
aromatic and aliphatic diva lent hydrocarbon linkage which
may contain ether or carbonyl oxygen linking groups. The
exterminated Solon is represented by the formula,
(E Syrup
wherein E is an epoxy-containing monovalent hydrocarbon
radical defined above, p is 1 to 3 (preferably 3) and R4
can be an aliphatic hydrocarbon radical of less than 10
carbon atoms such as alkyd (methyl, ethyl, isopropyl,
bottle), an alkenyl such a ally or vinyl, or an azalea
radical such as Eormyl, acutely, or propionyl. Because o-f
availability and performance, the preferred R4 is a lower
alkyd such as knothole or ethyl. Many illustrative examples
are described in U.S. Patent No. 4,049,861.
In addition to the Solon, any hydrolyzate of the
above sullenness can be used. Roy hydrolyzate is formed by
partial or complete hydrolysis of the Solon or groups as
described further in U.S. Patent No. 4,049,861.
3 The amount of the epoxy-terminated Solon or
hydrolyze can rancJe Eroln to about 98% of the
epoxypolysiloxane used, the amount being determined by the
release perforlnance desired. Gellerally, the hither amounts
ivy the hither release values.
122~
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Curing of the epoxypolysiloxane-containing compositions
of this invention can be effected by mixing with conventional
epoxy curing catalysts and may additionally require heat or
radiation. Examples of epoxy curing catalysts are tertiary amine,
Lewis acids and their complexes, such as BF3 and complexes with
ethers and amine; antimony halide-phosphorus containing ester
complexes, such as with organophosphonates, mentioned below;
polyaromatic iodonium and sulfonium complex salts (e.g., having
SbF6, SbF50H, PF6, BF4, or AsF6 anions, as disclosed in U.S.
Patent No. 4,101,513) and organic acids and their salts or other
derivatives such as the highly fluorinated sulfonic and sulfonylic
acids as described in U.S. Patent No. 4,049,861. The presence of
the catalyst in the cured composition does not affect its efficacy
as a release material.
In the practice of this invention the epoxypolysilox-
anew catalyst, and optionally, the epoxy-terminated Solon are
mixed in a solvent or, where possible, without solvent. The
amount of catalyst used is about 1 to I by weight of the epoxy
composition. The resultant material is coated on the image able
layer and cured at ambient temperatures or, where necessary, heated
to bring about cure. Solvents which can be used include ethyl
acetate, isopropyl acetate, acetone, methyl ethyl kitten, Hutton,
Tulane, and mixtures thereof. The exact coating technique is not
especially critical and any of several well known procedures can be
used. Warned rods, such as a Mayer bar, or a rotogravure
applicator roll having, for example, 80 lines per in, provide unit
form coating. Optionally, a mixing spray nozzle having a line for
the epoxypolysiloxane fluid or solution and a separate line for the
, . . .
lZ27636
-aye- 557-2797
catalyst solution can be used.
he coating thickness of the organopolysiloxane release
coating can be controlled to obtain optimum performance. Coating
weights in excess of 2.1 g/m2 tend to become soft and to deform
upon exposure to heat. This
..,
~227~3~
deformation can lead to irregularities in image areas,
resulting in light scattering, Wesley in turn can produce
dark spots in the projected image. The preferred range Ox
coating weight is from about 0.108 g/m2 to about 1.076
j 5 cg/m2. Tie most preferred range is from about 0.108 g/m2 to
about 0.538 g/m2
In some situations, a barrier coat must be
interposed between the layer bearing the imaging chemicals
and the release coating in order to permit the release
lo coating to cure. An examples of a suitable substance for
barrier coats is chlorinated polyisoprene (erg , Purloin
S-20, con~nercially available from Hercules, Inc.).
As a formulation for preparing a release coating
for thermally image able films, the composition of this
Lo invention is superior to those in conventional use for the
following reasons:
(1) the composition can be cured at temperatures
below about 70C, low enough to prevent damage
to imaging chemistry;
(2) the composition can be coated with a high speed
coating apparatus, e.g., rotogravure, reverse
roll;
(3) the cured coating is sufficiently permeable to
moisture, resulting in reduction of image edge
haziness, or "ghosting";
(4) the cured coating allows better release than
coatings currently used in the art;
(S) the cured coating has good release from toner
powder with the result that toner powder will
3 not adhere to the surface of the film
The imaging film of the present invention is also
vile useful in thermal printing devices, such as the
Hewlett-Packard 9800 series, The thermal print heads are
extremely hot, e.g., grow r ho :L00C, and eye have? a
nclency of icon Ox L toll ~her~llcll:Ly image able materials
from the substrate, resulting in fouled print heads. The
-15~ 76~
cohesive strength of the coating, combined with its low
coefficient of friction, render it useful for separating
the print head from the thermally image able materials.
The Hollowing examples present specific illustra-
} 5 lions of the present invention. It should be understood
that the invention is not intended to be limited to
specific details to be set earth therein.
EXAMPLE I
A composition for preparing a silicone polymer
10 release coating was prepared from a formulation containing
the following ingredients in the amounts indicated:
Ingredient Amount
Resin (Swahili 294) 4,00 g
Hutton 32.80 g
15 ethyl ethyl kitten 8.20 g
Cross-linking agent (Dow
Corning Q2-7131) 0.075 g
Catalyst (Dow Corning
ZOO) 0.150 g
The composition was coated over the image able layer of a
sheet of transparent infrared image able film by means of
knife coating. The wet coating thickness was 2 miss
(50.8 I). The coating was dried at a temperature of :l40F
~60C) for 3 minutes.
In this and the following ExaTnples II and III the
transparent infrared imageahle film was 4 mix (100 I)
Luke polyethylene terel)hthala~e sheet bearing on one Injury
surface thereof- an ilnageal~:L(? lucre coated prom a
i5Ormulatio,l containing the Hollowing ingredients in the
3 alienates indicated
7636
-16-
nut _ Amount
Nickel nitrate [Nina 0.102 g
2(2'-hydroxy-5'-methylpheny:L)-
benzotriazole 0.100 g
1(3-bromo-~N,N dLmethylamino-
phenyl)-2(2'-5'-chloro-
1',3',3'-trimethylindolyl)ethene 0.084 g
Phthalic acid Owls g
l-Phenyl-3-pyrazolidinone 0,102 g
lo Catcall 0.0~7 g
Vinylidene chloride-acrylonitrile
copolymer (Saran F-310, avail-
able from Dow Chemical Company) 1.500 g
Walt ncJ agent (Flurried FC-430,
fluorinated alkyd ester
available from Minnesota Mining
and Manufacturing Company) 0.001 g
'l'etrahydrofuran 1.333 g
Methyl ethyl kitten 4.980
Prior to coating, the above formulation was scaled-up L500X
and rotogravure coated with a 79.4 lines/in. knurl at 125
train with an oven dwell time of 68 seconds at a
temperature of 180~F (82C).
Identical plain paper copies were employed as
originals to determine the relative amount of toner
adhering to the infrared imaging film. The effectiveness
of the silicone release coaling was measured by comparing
the optical density values on release coated and uncoated
film from the same lot. The optical densities were
JO measured with a Macbeth Model TDSO~AM densitometer. The
images were made on a EM Model 45 infrared transparency
maker. The treated and untreated film samples were Ted
through the transparency malcer side-by-side so that both
were exposed to identical conditions. uncoated polyester
felon was used as a control. The results are set forth in
Table I:
63~
I ,'~
Jo I I I o
I I I o, I
'clue o It I I no
O O
0 10 1 1 0
I o o g Lo
.,, r~,~looooo
U I Lo on
g IT d' go
I
000~ I Jo
.~'~ owe Jo
I Lo or
En Lo I I
Jo
I I l Al O Jo
O H 1 o'er
4 rrJ H
h AL- I H Jo
I I r I I: rat I
rut rl
or' pi I roll C Jo
Jo 63~
Untreated infrared image able film, i.e., elm not
having a release coating, should remove more toner from an
original, i.e., a plain paper copy bearing removable toner
powder, than should an infrared image able illume treated will
the release coating of the present invention. Thy toner
which adheres to the untreated film will block light and
thereby raise the transmission optical density readincJs.
untreated image able ill and treated image able film should
give the same optical density readings when the image is
prepared prom a printed original, i.e. an original having
no removable toner, assuming that the films are selected
Erwin the same slot. Tiffs wow indeed true (See Sample A,
Table I When untreated polyester film having no image
receiving layer was used, only the base optical density ox
the film should was observed see Sample A, Table I). When
a plain paper copy original having removable toner was used
to produce a transparency with untreated polyester film
having no image receiving layer, an image resulting from
removed toner was observed and measured (See Sample C,
Table I).
A transparency prepared from a toned original and
an infrared image able film treated with an effective toner
release coating should exhibit a lower optical density
reading Han a transparency prepared from a toned original
and an untreated infrared imatJeable film from the same lo,
solely due to the absence of adhering toner material on the
treated film. This was shown to be true in Samples I, C,
D, and E of ruble I, Furthermore, because toner deposition
on the untreated film was not uniform, the standard
3 deviation of tune average image density readings was greater
for the untreated films than for the treated films. (See
Samples I, C, D, and E of fable I). In contrast, standard
deviations calculated For transparencies prepared from
printed originals were approximately the same for both
treated and untreated films (Lee Sample A, Table I).
--lo-- ~%2~-33~
EX~MJ?LE II
This example demonsL-Kates that only certain
classes ox silken resins are suitable o'er use yin the
prune invention.
Tile following fable sets forth ingredients and
amounts for four dif~erenl: release coating formulations:
TUB II
Ingredient Amount
A B C D
Rosen
Sulfa 294 3.12~
Swahili 3 10.000
Sulfa 291 2.500
Sulfa 292 ~.3S0
15Fast-cure additive
Dow Corning
C~-2117 0.300 0.300 0.300 0.250
Anchorage additive
Sulfa 297 0.200 0.150 0 200 0.100
catalyst
Dow Corning
ZOO 0.300 0.300 0.300
Dow Corning
AYE 0 650
25 solvent
Isopropanol 3.221 3.925 4.670 4.650
Methyl ethyl
Acetone ].. 07~
Hutton 38.655 35~325 42.030 36.585
3 Each formulation was coated over the immobile
layer of a sheet ox transparent infrared image able elan by
means ox knife coating. The wet coating thickness was 2
miss (50.8 I). The following table sets forth cure
results l-or the previously mentioned release coaxing
formulations
-20- ~27~3~
TABLE III
Temperature Time
Formulation (Cj Seiko) Nature of cure
-- .. . I. _
A 68 60 Good
B 82 90 Good
C 77 90 Good
D 82 90 None
Formulation D did no cure at 82C because Dow Corning 23
catalyst requires a higher curing temperature than does Dow
Corning MY 176 catalyst. Of the three formulations
wherein cure was effected, only formulation A could be
cured at a temperature below 70C. Formulations B and C
would not be suitable for use in the present invention
because the temperatures required to cure the release
coating formulation would adversely affect the layer of
image able material.
EXAMPLE III
A composition or preparing an epoxysiloxane
release coating was prepared prom a formulation containing
the following ingredients in the amounts indicated:
Ingredient Amount
Al 31 ¦ 1 3
(CH3)3Sio----SiO- --Six ---Seiko
SHEA 135 (SHEA I
I H 2
of H
. SHEA _ 15 3.0 g
-
Hutton 37.6 g
Methyl ethyl kitten 9.4 g
Antimony pentachloride/di.metlly:Lmethyl n. 3 q
l?ht~gphonal:te complex
i36
-21- 557-2797
The composition was coated over the image able layer of a sheet
of infrared image able film by means of knife coating. The wet
coating thickness was 2 miss (50.8 em). The coating was dried at
a temperature of 150F (66C) -for 1-1/2 minutes.
The effectiveness of the epoxypolysiloxane release
coating was determined by the same procedures and with the same
equipment as used in Example I. The results are set forth in
Table IV:
-2.2- ~27~;3~
I r-
(I JO O r-l O O ED
I Al O O O C: C l O
Al Us ' I
Jo
.
mu I I
I 1 I
.
rl Al I) ~71 Us
I 0 O O O I
r'l O O O O O
Roy
4
I
2 a
U Jo r-l I I I Jo rl
~1_1 .~)
I
I I I I 5
Jo Jo
b
1_1 I us .r1
,-1 in I I'
I r r l I r~3
I a H X Pi (I I
so to I us:;
I c: .
Jo ) ox a
I I U)
~2~7636
-23- 557-2797
From table IV, it is apparent that untreated infrared
image able film removed more toner from an original than did an
infrared image able film treated with an epoxypolysiloxane release
coating. In addition, standard deviation values of average image
density readings were greater for untreated films than for treated
films.
EXAMPLE IV
In this example, the transparent thermally image able
film was 4 mix (0.102 mm) thick polyethylene terephthalate sheet
bearing on one major surface thereof an image able layer prepared
according to the procedure described below. All parts are parts by
weight unless indicated otherwise.
A first solution containing (a) 5 parts silver been-
ate, (b) 40 parts acetone, and (c) 5 parts methyl ethyl kitten
was ball milled for 24 hours. A second solution containing (a)
13.00 parts polyvinyl acetate resin, (b) 83.20 parts acetone, (c)
0.20 parts benzotria~ole, (d) 0.60 parts tetrachlorophthalic
android, and (e) 3.00 parts methyl gullet was stirred until
the resin had dissolved. Twenty parts of the first solution was
combined with ten parts of the second solution, and the combination
was stirred for 5 minutes with an air mixer. The immobile compost
it ion was coated over the polyethylene terephthalate sheet with a
flat bed knife coaler at 3.0 mix orifice and was dried in an oven
at 82C for 2 minutes. A third solution containing 5 parts cell-
lose acetate bitterroot resin and 95 parts acetone was stirred until
the resin had dissolved. This solution was coated over the dried
image able composition with a knife coaler at 2.0 mix orifice and
was dried in an oven at 82C for 2 minutes. A fourth solution
,~,~
I
-aye- 557-2797
containing 7.5 parts polyvinyl bitterly and 92.5 parts ethanol was
coated over the cellulose acetate bitterroot resin layer with a knife
coaler at 2.0 mix orifice and was dried in an oven at 82C for 2
minutes
A composition for preparing a silicon polymer
release kitten was prepared Loom a formulation c~ntainin(J
the following ingredients in the amounts indicated:
Amount
5 Ingredient (parts by weight)
Resin (Sulfa 294) 4.00
Anchorage additive (Swahili 297) 0.25
Hutton 3~.00
Methyl ethyl kitten 6.00
10 Fast cure additive (Clue) 0.75
Catalyst (Dow Corning ZOO) 0.62
Hutton and methyl ethyl Acetone were blended, and then, in
order were added the resin the East-cure additive, the
anchorage additive, and the catalyst. The release coating
composition was coated over the polyvinyl bitterly layer by
means cue a knife coaler a a 2 mix orifice. The coating
was dried in an oven at 82C -for 2 minutes
The effectiveness ox the rslea~e coating was
determined through the measurement and comparison ox the
optical density of the image on tile paper original prior Jo
making a transparency, after making a transparency with
thermally imacgeable film not treated with a silicone
release coating, and after making a transparerlcy with
thermally image able film treated with a silicone release
coating (A fresh original was used to prepare each
tratlsparency.) Originals were Include on a Cadillac Model 15~
copier. Transparencies were made on a prewarmed EM Model
45 Transparency Make Roy optical densities were measured
with a Luke Ludlow Tl~924 densitometer. The results in
3 the Elan table represent the average of four samples.
12~7~3~
-25- 557-2797
TABLE V
Optical density Standard deviation
Original 1.21 0.08
Untreated film 0.98 0.22
Treated film 1.21 0.12
Loss of optical density and increase in standard deviation is
observed when comparing the images on originals before and after
imaging with untreated film. Loss of optical density results from
toner particles being torn from the paper original. Because
tearing away of toner particles is not uniform, the standard
deviation increases. When treated film is used, no loss of optical
density is observed. Furthermore, the standard deviation is only
slightly higher than that of the original image, thus indicating
the uniformity of image is about the same.
"
