U.S. patent number 3,864,132 [Application Number 05/255,331] was granted by the patent office on 1975-02-04 for article having a hydrophilic colloid layer adhesively bonded to a hydrophobic polymer support.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Herbert B. Cowden, Arthur A. Rasch, David P. Sullivan.
United States Patent |
3,864,132 |
Rasch , et al. |
February 4, 1975 |
Article having a hydrophilic colloid layer adhesively bonded to a
hydrophobic polymer support
Abstract
An article is disclosed characterized by a hydrophobic polymer
support and a supported portion having a surface comprising a
hydrophilic colloid layer which is bonded to the support by an
adhesive layer containing an inorganic oxide such as silicon oxide,
aluminum oxide, magnesium oxide, tantalum oxide, titanium oxide,
boron-silicon oxide, and mixtures thereof. The article can be a
photographic article including a radiation sensitive material such
as silver halide.
Inventors: |
Rasch; Arthur A. (Webster,
NY), Cowden; Herbert B. (Rochester, NY), Sullivan; David
P. (Rochester, NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
22967833 |
Appl.
No.: |
05/255,331 |
Filed: |
May 22, 1972 |
Current U.S.
Class: |
430/496; 430/954;
430/524 |
Current CPC
Class: |
G03C
1/853 (20130101); G03C 1/91 (20130101); Y10S
430/155 (20130101) |
Current International
Class: |
G03C
1/85 (20060101); G03C 1/91 (20060101); G03c
001/94 () |
Field of
Search: |
;96/87R,67,29L,85,1R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Torchin; Norman G.
Assistant Examiner: Goodrow; John
Attorney, Agent or Firm: Lewis; J. T.
Claims
What is claimed is:
1. In a photographic article comprising a radiation-sensitive
silver salt, a support having a hydrophobic polymer supporting
surface, a hydrophilic colloid layer and a subbing layer which is
contiguous to said supporting surface and said hydrophilic colloid
layer and is bonded to each, the improvement in which said subbing
layer is binderless and consists essentially of an inorganic oxide
selected from the group consisting of silicon oxide, magnesium
oxide, aluminum oxide, tantalum oxide, titanium oxide, boro-silicon
oxide and mixtures thereof and is from 10 to 1000 angstroms
thick.
2. The invention according to claim 1 in which said support is a
polyester film support.
3. The invention according to claim 1 in which said hydrophobic
polymer is polyalkylene terephthalate.
4. The invention according to claim 1 in which said support is
polyolefin coated paper.
5. The invention according to claim 1 in which said silicon oxide
is silicon monoxide or silicon dioxide.
6. The invention according to claim 1 additionally including a
metal layer associated with the surface of said support which is
opposite from said subbing layer.
7. The invention according to claim 1 in which said subbing layer
exhibits a thickness in the range of from 50 to 500 angstroms.
8. In a photographic article comprising a radiation-sensitive
silver salt, a flexible hydrophobic polyester film support, a
gelatin layer and a subbing layer interposed between and bonded to
said film and said gelatin layer, the improvement in which said
subbing layer is vapor deposited to a thickness of from 50 to 500
angstroms and comprises a binderless inorganic oxide selected from
the group consisting of silicon oxide, magnesium oxide, tantalum
oxide, titanium oxide and mixtures thereof.
9. A photographic article according to claim 8 in which said
support is polyethylene terephthalate.
10. A photographic article according to claim 8 in which said
support is polyethylene terephthalate, said radiation-sensitive
material is a silver halide and said inorganic oxide is silicon
oxide.
11. A photographic article according to claim 10 in which said
silver halide is silver bromochloride.
Description
This invention relates to improving the adhesion of hydrophilic
colloid layers to hydrophobic support surfaces. In one aspect, this
invention relates to articles having a hydrophilic colloid layer
and a hydrophobic support surface which are bonded by an interposed
inorganic oxide adhesive layer, for example, a metal oxide adhesive
layer. In another aspect, this invention relates to a photographic
article in which a hydrophilic colloid layer of a radiation
sensitive portion of the article is bonded to a hydrophobic support
surface using an inorganic oxide subbing or adhesive layer.
It has been recognized that colloid layers which are hydrophilic in
nature in order to be uniformly permeable to aqueous solutions
utilized in photographic processing, do not readily or uniformly
bond to hydrophobic polymer supports with the tenacity that is
frequently desired. Since the majority of the photographic
supports, principally film and resin coated paper supports,
utilized with such hydrophilic colloid layers are hydrophobic, it
is common practice to treat the surface of these supports so that
they present a hydrophilic surface for receipt of the colloid layer
to be bonded.
For example, in the case of polyethylene terephthalate films, which
exhibit a comparatively marked degree of hydrophobicity, one
approach to achieving the desired tenacious bonding of a
hydrophilic colloid such as gelatin to the film is to deposit on
the polyester film a comparatively complex terpolymer subbing layer
containing dissimilar monomeric units which promote adherence
between the hydrophobic and the hydrophilic materials. The
terpolymer firmly and uniformly adheres to hydrophobic polyethylene
terephthalate film surfaces and also to hydrophilic gelatin
surfaces and in this way a reliable and strong indirect bond is
achieved between the gelatin and the film.
A principal disadvantage of such subbing layers is that they are
complex and hence add significantly to the time and cost of
photographic article manufacture. The complexity is reflected both
in bonding layer preparation and control, particularly where
complex polymers are utilized, and in achieving compatibility with
radiation-sensitive article portions. Compatibility with the
radiation-sensitive materials and addenda normally associated with
photographic articles is particularly demanding. Also, the subbing
layers must be compatible with the processing solutions brought
into contact with the radiation-sensitive articles after
exposure.
While common photographic film supports are typically hydrophobic
and do not adhere well to hydrophilic colloids, it has been
observed that such supports are, with respect to certain types of
coatings, excessively adherent. For example, metal anti-static
layers have been employed in photographic articles in the past.
However, when a metal anti-static layer is vacuum deposited onto a
film support and the coated film wound in reel form in the vacuum
chamber before exposure to air, the metal frequently will adhere to
both adjacent film surfaces. When this occurs the metal may cause
"blocking"-- i.e. prevent unwinding of the reel or, if unwinding is
in fact accomplished, the metal coating may be partially and
randomly transferred to the opposite surface of the polymer
support.
Prior to this invention it has been recognized that vapor deposited
inorganic oxides are, like vapor deposited metals, readily adherent
to glass and plastic surfaces. It has also been recognized that
certain vapor deposited inorganic oxides may in turn receive vapor
deposited overlayers, such as vapor deposited metal oxide, metal
halide and metal overlayers, and thereby bond any such overlayer to
a support. For example, Agfa British Pat. No. 1,066,944, published
Apr. 26, 1967, teaches using certain vapor deposited metal oxides
as adhesives for vapor deposited metal halides.
Such vapor deposited overlayers, however, differ markedly in
physical properties from hydrophilic colloids. In addition to being
hydrophilic, which in itself renders the colloids difficult to bond
to hydrophobic surfaces, hydrophilic colloids also ingest water
when brought into contact with aqueous solutions, such as
photographic processing solutions. The ingestion of water creates
substantial dimensional changes in the hydrophilic colloid and/or
large internal stresses, particularly at a bonding interface. For
example, a hydrophilic colloid layer may ingest a quantity of water
several times its original weight leading to doubling, tripling or
greater increase in its original thickness. When a hydrophilic
colloid is deposited directly on a hydrophobic support, it can be
sloughed from the support on swelling of the layer during exposure
to aqueous solutions. Accordingly the art has heretofore generally
utilized terpolymers as above noted as subbing layers to facilitate
adhesion of hydrophilic colloid layers to hydrophobic support
surfaces.
It is an object of this invention to provide an article in which
the bonding of an article portion presenting a surface comprised of
a hydrophilic colloid to a hydrophobic polymer support surface is
achieved using an interposed adhesive layer that is of low cost and
complexity.
It is another object to provide a photographic article having a
radiation sensitive portion comprising a hydrophilic colloid layer
which is bonded to a hydrophobic polymer support surface by means
of an interposed subbing layer that is relatively inert and
insoluble in the course of photographic processing and also that is
compatible with radiation sensitive materials and addenda.
It is still another object to provide a photographic article
bearing a metal layer that is protected against blocking by an
inorganic oxide layer positioned on a major surface of the support
opposite to the metal layer.
These and other objects of this invention are accomplished in one
aspect by an article comprising a support having a hydrophobic
polymer supporting surface, a hydrophilic colloid layer and an
adhesive layer which is contiguous to the supporting surface and
the hydrophilic colloid layer and is bonded to each. The adhesive
layer comprises an inorganic oxide selected from the group
consisting of silicon oxide, aluminum oxide, tantalum oxide,
magnesium oxide, titanium oxide and mixtures thereof. In a
preferred form the article contains a radiation-sensitive material.
A metal layer can be associated with a surface of the support from
which the subbing layer is absent.
In accordance with this invention it has been found that a
hydrophilic colloid layer can be firmly bonded to a hydrophobic
polymer supporting surface by means of an inorganic oxide adhesive
layer which is contiguous to the supporting surface and to the
hydrophilic colloid layer. Such adhesive layers (commonly referred
to as subbing layers in the photographic arts) are binderless
layers which consist essentially of inorganic metal oxide and are
capable of bonding directly and tenaciously to both hydrophilic
colloid layers and to hydrophobic polymeric support surfaces to
perform the function heretofore performed by considerably more
complex polymer layers. The term "binderless layer" refers to a
layer that is substantially free of organic adhesive materials and
refers particularly to the absence of those organic adhesive and
binder materials commonly utilized in the photographic arts, such
as natural and synthetic polymeric binders and colloidal vehicles.
The binderless adhesive layer may be formed of crystalline or
amorphous inorganic oxides. In a preferred form the adhesive layer
is a glass.
It is a surprising feature of this invention that the hydrophilic
colloid remains tenaciously bonded by the inorganic oxide to the
hydrophobic support surface when the article is immersed in colloid
swelling aqueous solutions and when the article is subjected to
mechanical flexure of the support and colloid. In the course of
processing after exposure, photographic articles bearing
radiation-sensitive colloid layers are often brought into
association with alkaline, acid and/or neutral aqueous solutions in
accordance with procedures well known to those skilled in the art.
In the course of such processing the colloid layer, being water
permeable, ingests appreciable quantities of aqueous solution, and
the increase in volume of the emulsion layer can produce marked
dimensional changes and/or internal stresses. The inorganic oxide
layer utilized in the practice of this invention remains
comparatively stable during such photographic processing.
Furthermore, despite dimensional changes and stresses produced
during photographic processing a colloid layer is rendered highly
adherent by an inorganic oxide layer even when subjected to
mechanical stress, as, for example, when binding a colloid layer to
a flexible support that is wound or repeatedly flexed.
It is a surprising feature of this invention that not only does the
inorganic oxide layer serve as an excellent adhesive between the
hydrophobic polymer surface and the hydrophilic colloid surface,
but, additionally, this layer may be relied upon to prevent
undesired adhesion of a metal to the support surface. For example,
it has been observed that where a metal layer is deposited on a
hydrophobic polymer film support and the film is wound on a reel
prior to allowing the metal surface to become oxidized, the metal
will adhere to both adjacent surface of the film. This may lead to
blocking, preventing unwinding of the film, or the metal may adhere
randomly to the opposite surfaces of the film. To cite a specific
example, in vacuum depositing a metal anti-static coating onto a
film surface in an evacuated enclosure, it is necessary, in order
to coat appreciable lengths of film, to wind the film from one reel
to another during coating and before air exposure occurs. The
resulting adhesion and/or partial transfer of the metal anti-static
coating to the opposite surface of the film upon unwinding poses a
substantial difficulty. Where an inorganic oxide layer is formed on
one major surface of the film, a freshly deposited metal layer on
the opposite surface of the film will not transfer to the adjacent
inorganic oxide surface on winding and will not adhere to the metal
oxide surface so as to prevent unwinding of the film. In comparing
colloid coated films with and without inorganic oxide bonding
layers provided according to this invention, similar improvements
in preventing the colloid layer from being pulled away by the metal
layer are obtained with those films having inorganic oxide bonding
layers.
In the articles of this invention the overall thickness of the
adhesive layer can be widely varied. To the extent that the layer
is formed so thin that it does not fully cover the support surface
the advantages of this invention may be at least partially
diminished. At the same time, for many photographic applications it
is desirable to limit the layer thickness employed so that the
optical density of the photographic article is not objectionably
increased. For many applications and photographic applications
particularly layer thicknesses of from 10 to 1000 angstroms are
desirable, with thicknesses of from 50 to 500 angstroms being
preferred. Binderless adhesive (or subbing) layers consisting
essentially of inorganic oxide according to this invention may be
readily formed by conventional vacuum vapor deposition procedures
as well as by other techniques generally known to those skilled in
the art.
Adhesive layers employed in the practice of this invention are
prepared from inorganic oxides. Oxides of silicon, such as silicon
monoxide and silicon dioxide, are preferred inorganic oxides, since
they are substantially water insoluble and chemically inert in
photographic processing and use environments and are essentially
transparent. Silicon oxides are also preferred since they can be
vapor deposited by heating to vaporization temperatures that are
low as compared to those required for vaporizing the other
inorganic oxides utilized in the practice of this invention.
Aluminum oxide, boron-silicon oxide, magnesium oxide, tantalum
oxide and titanium oxide as well as mixtures thereof are
particularly suited to the practice of this invention.
The inorganic oxide adhesive layer may be utilized on any
hydrophobic supporting surface. Typical hydrophobic polymers which
form supporting surfaces according to this invention include
cellulose esters such as cellulose nitrate and cellulose acetate;
poly(vinyl acetal) polymers, polycarbonates, polyesters such as
polymeric, linear polyesters of bifunctional saturated and
unsaturated aliphatic and aromatic dicarboxylic acids condensed
with bifunctional polyhydroxy organic compounds such as polyhydroxy
alcohols--e. g. polyesters of alkylene glycol and/or glycerol with
terephthalic, isophthalic, adipic, maleic, fumaric and/or azelaic
acid; polyhalohydrocarbons such as polyvinyl chloride; and
polymeric hydrocarbons, such as polystyrene and polyolefins,
particularly polymers of olefins having from 2 to 20 carbon atoms.
The above polymers may be utilized in the form of flexible films or
other unitary supports or may be utilized as coatings on metal,
glass, paper and polymer supports. A preferred class of coated
supports is alpha-olefin resin coated paper supports, such as paper
supports coated with polyethylene, polypropylene, ethylene-butene
copolymers and the like.
The hydrophilic layer to be adhesively bonded to the hydrophobic
polymeric support surface can be formed from one or more
hydrophilic, water permeable colloid forming substances including
both naturally occurring substances such as, for example, proteins
such as gelatin and gelatin derivatives; cellulose derivatives;
polysaccharides such as dextran, gum arabic and the like and
synthetic polymer substances, such as water soluble polyvinyl
compounds like poly(vinylpyrrolidone), acrylamide polymers and the
like.
The hydrophilic colloids utilized can also contain other synthetic
polymeric compounds such as those which increase the dimensional
stability of the colloid layers. Suitable synthetic polymers
include those described, for example, in Nottorf U.S. Pat No.
3,142,568, issued July 28, 1964; White U.S. Pat. No. 3,193,386,
issued July 6, 1965; Houck et al. U.S. Pat. No. 3,062,674, issued
Nov. 6, 1962; Houck et al. U.S. Pat. No. 3,220,844, issued Nov. 30,
1965; Ream et al. U.S. Pat. No. 3,287,289 issued Nov. 22, 1966; and
Dykstra U.S. Pat. No. 3,411,911 issued Nov. 19, 1968. Particulary
effective are those water-insoluble polymers of alkyl acrylates and
methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates,
those which have cross-linking sites which facilitate hardening or
curing described in Smith U.S. Pat. No. 3,488,708, issued Jan. 6,
1970, and those having recurring sulfobetaine units as described in
Dykstra Canadian Pat. No. 774,054.
The hydrophilic colloid can be hardened by various organic or
inorganic hardeners, alone or in combination, such as the aldehydes
and blocked aldehydes described in Allen et al. U.S. Pat. No.
3,232,764, issued Feb. 1, 1966, ketones, carboxylic and carbonic
acid derivatives, sulfonate esters, sulfonyl halides and vinyl
sulfonyl ethers as described in Burness et al. U.S. Pat. No.
3,539,644 issued Nov. 10, 1970, active haolgen compounds, epoxy
compounds, aziridines, active olefins, isocyanates, carbodiimides,
polymeric hardeners such as oxidized polysaccharides like
dialdehyde starch and oxyguargum and the like.
Where the article formed is employed in forming an image by
exposure to activating radiation that portion of the article to be
bonded to the support will contain in or on it a
radiation-sensitive material. This material may be panchromatic or
orthochromatic material, sensitive only to X-rays or sensitive to
selected portions of the electromagnetic spectrum. In one form of
the invention the radiation-sensitive portion of the photographic
article can contain a single, unitary hydrophilic colloid layer
having dispersed therein the radiation-sensitive material together
with photographic addenda to form a photographic emulsion layer or
coating having a hydrophilic colloid surface. In alternative forms
the radiation-sensitive portion of the article can comprise a
plurality of layers with the radiation-sensitive material or
materials being contained in some or all of the layers, but not
necessarily in the hydrophilic colloid layer immediately adjacent
the inorganic oxide subbing layer. For example, as is
characteristic of color photography, a plurality of layers can be
present sensitized within separate segments of the visible
spectrum. While each of the layers can comprise a hydrophilic
colloid photographic emulsion coating or layer, it is recognized
that only the bonding surface of the radiation sensitive portion of
the article need be comprised of hydrophilic colloid in order to
achieve the objectives of this invention. Suitable hydrophilic
colloid layers which can be bonded to a hydrophobic support surface
but which contain no radiation-sensitive material, such as silver
halide, when coated include, for example, antihalation layers,
nucleated chemical transfer receiving layers, dye-mordant layers
and the like.
Suitable radiation-sensitive materials which can be employed in
practicing this invention are sensitive to electromagnetic
radiation and include such diverse materials as silver salts, zinc
oxide, photosensitive polycarbonate resins and the like. Silver
halides are preferred radiation-sensitive materials and are
preferably associated with a colloid or synthetic polymer
dispersion vehicle to form an emulsion coating or layer. Silver
halide emulsions can comprise, for example, silver chloride, silver
bromide, silver bromoiodide, silver chlorobromide, silver
chloroiodide, silver chlorobromoiodide crystals or mixtures
thereof. The emulsions can be coarse or fine grain emulsions and
can be prepared by a variety of techniques, e.g. single jet
emulsions such as those described in Trivelli and Smith The
Photographic Journal, Vol. LXXIX, May, 1939 (pp. 330-338), double
jet emulsions such as Lippmann emulsions, ammoniacal emulsions,
thiocyanate or thioether ripened emulsions such as those described
in Nietz et al. U.S. Pat. No. 2,222,264, issued Nov. 19, 1940;
Illingsworth U.S. Pat. No. 3,320,069, issued May 16, 1967, and
McBride U.S. Pat. No. 3,271,157, issued Sept. 6, 1966. Negative
type emulsions can be made, as well as direct positive emulsions as
described in Leermakers U.S. Pat. No. 2,184,013, issued Dec. 19,
1939; Kendall et al. U.S. Pat. No. 2,541,472, issued Feb. 13, 1951;
Schouwenaars British Pat. No. 723,019, issued Feb. 2, 1955;
Illingsworth et al. French Pat. No. 1,520,821, issued Mar. 4, 1968,
Illingsworth U.S. Pat. No. 3,501,307, issued Mar. 17, 1970; Ives
U.S. Pat. No. 2,563,785, issued Aug. 7, 1951, Knott et al. U.S.
Pat. No. 2,456,953, issued Dec. 21, 1948 and Land U.S. Pat. No.
2,861,885, issued Nov. 25, 1958.
The silver halide emulsions employed in the articles of this
invention can be sensitized with chemical sensitizers, such as
with: reducing compounds; sulfur, selenium or tellurium compounds;
gold, platinum or palladium compounds; or combinations of
these.
The photosensitive emulsion coatings or layers can additionally
include a variety of conventional addenda both for the colloid and
for the radiation-sensitive material. For example, photographic
emulsion layers employed according to this invention may include
development modifiers, antifoggants and stabilizers, plasticizers
and lubricants, brighteners, spectral sensitization agents and
color forming materials as set forth in paragraph IV, V, XI, XIV,
XV, and XXII, respectively, of Product Licensing Index, Vol. 92,
December, 1971, publication 9232, pages 107- 110.
As previously indicated photographic articles of this invention can
be processed with aqueous photographic processing solutions.
Photographic articles containing the inorganic oxide subbing layers
described herein can also be used in non-aqueous processing-- e.g.
in so-called dry processing systems. For example, the subbing
layers described herein can be used in silver halide containing
articles designed for recording print out images as described in
Fallesen U.S. Pat No. 2,369,449 issued Feb. 13, 1945 or Bacon et
al. U.S. Pat. No. 3,447,927 issued June 3, 1969; direct print
images as described in Hunt U.S. Pat. No. 3,033,682 issued May 8,
1962 and McBride U.S. Pat. No. 3,287,137 issued Nov. 22, 1966; and
articles designed for processing with heat, such as in articles
containing an oxidation-reduction image-forming combination with a
photosensitive metal salt such as a silver salt as described in
Sheppard et al. U.S. Pat. No. 1,976,302 issued Oct. 9, 1934;
Sorensen et al. U.S. Pat. No. 3,152,904 issued Oct. 13, 1964 and
Morgan et al. U.S. Pat. No. 3,457,075 issued July 22, 1969.
A metal anti-static layer can be utilized in the practice of this
invention. Such a layer is conveniently coated on the opposite side
of the support on which the radiation-sensitive material is to be
coated. Preferred metals for forming anti-static layers on
polymeric film supports are chromium, silver, nickel, and aluminum.
Typically the metal anti-static layers are kept as thin as is
consistent with providing the required surface resistivity
characteristics. A metal anti-static layer in order to be effective
must generally provide a surface resistivity of less than 10.sup.12
ohms per square, with surface resistivities of less than 10.sup.8
ohms per square being preferred for most photographic applications.
To insure that all areas of a photographic article exhibit a
surface resistivity of less than 10.sup.8 ohms per square, it is
generally preferred that the article exhibit an overall surface
resistivity of less than 10.sup.5 ohms per square. As is well
understood by those skilled in the art surface resistivity is
determined by measuring the resistance between two parallel
electrodes of a given length spaced apart by the same distance
along a surface. Since an increase in the length of the electrodes
tends to decrease the resistance observed by an amount equal to
that by which the resistance would be increased by lengthening the
spacing between the electrodes by a like increment, it is apparent
that the electrode length and spacing is not material so long as
they are identical. Hence the surface resitivity expressed in ohms
per square is a resistance measurement taken for the special case
in which electrode length and spacing are identical and therefore
mutually cancelling parameters.
Metal anti-static layers providing surface resistivities within the
above criteria are generally formed having thicknesses of less than
500 angstroms and, preferably, less than 100 angstroms. By limiting
the thickness of the metal anti-static layer its optical density is
limited and the amount of metal which may enter film processing
solutions during film development and processing is limited.
It is, of course, recognized that the photographic article formed
according to this invention can, if desired, incorporate
anti-static or conducting layers other than or in addition to metal
anti-static layers. Such layers can comprise soluble salts, e.g.
chlorides, nitrates, etc., ionic polymers such as those described
in Minsk U.S. Pat. No. 2,861,056, issued Nov. 18, 1958, and Sterman
et al. U.S. Pat. No. 3,206,312, issued Sept. 14, 1965, or insoluble
inorganic salts such as those described in Trevoy U.S. Pat. No.
3,428,451, issued Feb. 18, 1969.
This invention may be better understood by reference to the
drawings, which are each fragmentary sectional views of
photographic articles according to this invention. For ease of
illustration the various elements of the articles are not drawn to
scale.
FIG. 1 illustrates an article 1 comprising a hydrophobic polymer
support 3. A hydrophilic colloid coating 5 is located by the
support and is adhesively bonded thereto by an inorganic oxide
layer 7 according to this invention. An optional metal anti-static
layer 9 is bonded to the major surface of the polymer support not
bonded to the colloid coating.
FIG. 2 illustrates a photographic article 10 in which a dielectric
support 12 is provided with a hydrophobic polymer layer 14 adjacent
one major surface. A radiation-sensitive hydrophilic colloid
coating 16 containing radiation-sensitive material is adhesively
bonded to the hydrophobic polymer layer by an inorganic oxide layer
18.
FIG. 3 illustrates a photographic article 100 in which a dielectric
support 102 is provided with a hydrophobic polymer layer 104
adjacent one major surface. An inorganic oxide layer 106 bonds a
radiation-sensitive portion 108 of the article to the hydrophobic
polymer surface presented by the layer 104. The radiation-sensitive
portion 108 is comprised of a hydrophilic colloid layer 110, which
is as coated substantially free of radiation-sensitive materials,
and a radiation-sensitive emulsion layer 112, which overlies the
layer 110.
To further illustrate the invention the following examples are
included:
EXAMPLE 1
To illustrate the non-blocking characteristics of the inorganic
oxide coatings of this invention and to prepare supports protected
against blocking for use in subsequent comparisons a glass is
deposited on one major surface of several rolls of polyethylene
terephthalate film support in the following manner: A roll of
support is loaded into a conventional vacuum roll coater, and a
boro-silicon oxide coating is deposited by placing a boro-silicon
oxide (i.e. borosilicate) glass available as Code 8329 glass
(manufactured by Jena Glaswerk Schott and Gen., Mainz, West
Germany) in the crucible of an electron beam heated vapor source.
The vacuum chamber is closed and pumped down to a pressure of 7.2
.times. 10.sup..sup.-5 Torr. The glass is heated in an electron
beam until it is evaporating at a high rate. Shutters protecting
the support from the vapor are opened and the support is drawn
through the vapor stream at a rate such that the boro-silicon oxide
glass coating that condenses on the support forms a film of less
than 100 angstroms thick. After coating, the source is cooled, the
pressure in the chamber raised to atmospheric pressure, and the
coated roll reloaded in the system so that all subsequent coatings
are made on the side opposite the glass coating. This first glass
coating is non-blocking and is provided to assure direct
comparability of later coatings. It should be recognized that
oxides of silicon, titanium, tantalum, aluminum and magnesium are
also non-blocking and can be deposited singly or in combination in
place of the glass layer.
EXAMPLE 2
In order to compare the qualities of inorganic oxide, metal and
terpolymer subbing layers in promoting the adhesion of hydrophilic
colloid layers to hydrophobic polymer film supporting surfaces, to
the support surfaces opposite the non-blocking glass layers several
adhesive coatings, as designated in Table I, are deposited using
the above vacuum vapor deposition procedure. As indicated in Table
I one roll is coated with boro-silicon oxide on both major surfaces
and, for purposes of comparison, aluminum, nickel and silicon
dioxide are deposited on glass coated rolls of the support. Layer
parameters are set forth in Table I.
TABLE I ______________________________________ Layer Thickness Net
Optical Density ______________________________________ Nickel 40A
0.21 Aluminum 100 0.41 Silicon monoxide 250 0.00 Boro-silicon oxide
100 0.00 Silicon dioxide 50 0.00
______________________________________
The net optical densities are determined using an optical
densitometer; the net optical densities in each instance being the
difference between the optical densities of otherwise identical
coated and uncoated supports. It can be seen that the inorganic
oxide layers are advantageous in failing to significantly add to
the optical density of the articles.
The supports having the coatings described in the above Table I are
stored in rolls for two weeks under ambient conditions and then
overcoated with a gelatin silver bromoiodide photographic emulsion
at a coverage equivalent to 400 mg of silver/ft.sup.2. In addition,
film supports of uncoated polyethylene terephthalate and
polyethylene terephthalate coated with a conventional subbing layer
formed of a terpolymer of methyl acrylate, vinylidene chloride and
acrylic acid are are similarly overcoated with this emulsion.
The dry, unprocessed photographic emulsion adheres very poorly to
the unsubbed support and flakes off when the support is flexed or
twisted. This effect does not appear on any of the articles which
are provided with a layer interposed between the support and the
photographic emulsion coating. This indicates that prior to
processing each of the interposed layers to some extent improves
the bond between the support and the hydrophilic emulsion
coating.
To illustrate the effects of photographic processing on the
adhesion of the emulsion coatings to the supports like-sized strips
are cut from the supports having the aluminum, boro-silicon oxide
and terpolymer subbing layers. In the first comparison the emulsion
coating is scribed to the support with an 0.1 mm stylus and the
article is processed under conditions of high agitation as follows:
Each emulsion coated support is developed in a buffered aqueous
developing solution having a pH of approximately 10 and
incorporating equal parts by weight p-methyl aminophenol and
hydroquinone for 2 minutes at 23.degree.C, followed by 3 minutes
fixation in a sodium thiosulfate containing aqueous fixing bath.
Peel is measured in millimeters from the originally scribed line to
the remaining adjacent edge of the emulsion. Exemplary results are
set forth as Comparison No. 1 in Table II.
In a second comparison, using strips identical to that used in the
first comparison, a 1 -inch circle of the emulsion coating on each
strip is identically washed at 70.degree.C and dried. Thereafter
the percent peel from the strip is measured by observing the area
within the 1 -inch circle from which the emulsion coating has
spalled during washing and by calculating this as a percentage of
the total circle area. Exemplary results of Comparison No. 2 are
set forth in Table II.
TABLE II ______________________________________ Layer Comparison
No. 1 Comparison No. 2 mm peel % peel
______________________________________ Aluminum Complete peel
Complete peel Boro-silicon oxide 4.3 4 Ter-polymer 1.4 1
______________________________________
While the boro-silicon oxide adhesive layer does not bond quite as
well as considerably more complex conventional terpolymer subbing
layer, it bonds considerably better than the aluminum, which is
representative of oxidizable metal layers. At the same time the
degree of bonding afforded by the boro-silicon oxide layer under
the stringent conditions provided fully demonstrates its highly
adhesive characteristics. In a similar manner, an article can be
prepared in which a gelatin layer containing no silver bromoiodide
is substituted for the gelatin silver bromoiodide photographic
emulsions employed in this example. Such an article also possesses
excellent adhesion characteristics.
EXAMPLE 3
To illustrate that the inorganic oxide layers employed in the
practice of this invention are non-blocking and may be utilized to
prevent blocking of metal layers associated with the support, such
as anti-static layers, a plain, untreated polyethylene
terephthalate film support is coated with an approximately 100
angstrom thick film of silicon monoxide using the equipment and
techniques described in Example 1. An additional sample of
untreated support is spliced to the metal oxide coated sample and
another coating run made in which a nickel film approximately 50
angstroms thick was deposited on the side of the substrate opposite
the silicon monoxide film and on one side of the uncoated
substrate. When the coated support is unrolled, it is found that
the section of support coated with nickel alone blocks badly and
the nickel film is partially stripped from the coated surface
during unwinding. In that part of the roll which is protected with
the silicon monoxide layer, no blocking occurs, and the support is
unwound without damaging the nickel film.
* * * * *