U.S. patent number RE32,514 [Application Number 06/862,346] was granted by the patent office on 1987-10-06 for polymer compositions having a low coefficient of friction.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to David J. Steklenski.
United States Patent |
RE32,514 |
Steklenski |
October 6, 1987 |
Polymer compositions having a low coefficient of friction
Abstract
Polymer compositions which have a low coefficient of friction
are disclosed. The polymer compositions comprise a blend of at
least 80 percent by weight of a solid of film-forming polymer and
at least 0.35 percent by weight of a crosslinked silicone
polycarbinol. The described composition retains its low coefficient
of friction even after being exposed to hydrocarbon solvents during
a cleaning process. The described compositions are particularly
useful in forming protective layers for elements, particularly
photographic elements.
Inventors: |
Steklenski; David J.
(Rochester, NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
27012264 |
Appl.
No.: |
06/862,346 |
Filed: |
May 12, 1986 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
388321 |
Jun 14, 1982 |
4404276 |
|
|
Reissue of: |
503488 |
Jun 13, 1983 |
04473676 |
Sep 25, 1984 |
|
|
Current U.S.
Class: |
524/32; 427/387;
428/447; 430/272.1; 430/531; 430/961 |
Current CPC
Class: |
C08L
1/18 (20130101); G03C 1/7614 (20130101); G03C
11/08 (20130101); C08L 1/18 (20130101); Y10T
428/31663 (20150401); C08L 2666/02 (20130101) |
Current International
Class: |
C08L
1/00 (20060101); C08L 1/18 (20060101); G03C
1/76 (20060101); G03C 11/08 (20060101); G03C
11/00 (20060101); C08L 001/28 (); G03C
001/78 () |
Field of
Search: |
;524/31,32,33
;430/272,531,631,961 ;428/446,447 ;427/387,393.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
740041 |
|
Aug 1966 |
|
CA |
|
924102 |
|
Feb 1955 |
|
DE |
|
1201995 |
|
Aug 1970 |
|
GB |
|
1424429 |
|
Feb 1976 |
|
GB |
|
1437865 |
|
Jun 1976 |
|
GB |
|
1483673 |
|
Aug 1977 |
|
GB |
|
2016167 |
|
Sep 1979 |
|
GB |
|
628149 |
|
Sep 1978 |
|
SU |
|
Other References
Polymer Blends, Paul et al., Ed., vol. 1, Academic Press, New York,
1978, pp. 54-63. .
"Organofunctional Silicone Fluids--Silicone Polycarbinols", Dow
Corning Corp., Technical Bulletin..
|
Primary Examiner: Foelak; Morton
Assistant Examiner: Nutter; Nathan M.
Attorney, Agent or Firm: Marshall; Paul L.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a divisional of U.S. Ser. No. 388,321,
filed June 14, 1982, now U.S. Pat. No. 4,404,276, which is related
to U.S. Ser. No. 388,322, filed of even date herewith, issued as
U.S. Pat. No. 4,431,727 entitled PROTECTIVE OVERCOATS FOR
PHOTOGRAPHIC ELEMENTS by Steklenski.
Claims
What is claimed is:
1. A composition comprising a blend of at least 80 percent by
weight of a polymer and at least 0.35 percent by weight of a
crosslinked .[.silicone polycarbinol.]. .Iadd.member of the group
consisting of:
(a) a hydroxy-terminated polysiloxane of the general structure:
##STR3## wherein each of R.sup.1 and R.sup.2 is independently
selected from the group consisting of hydrogen, alkyl and aryl and
w is an integer from about 100 to about 2500, and
(b) a graft hydroxy functionalized polysiloxane having the general
structure: ##STR4## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and
R.sup.5 are each independently selected from the group consisting
of hydrogen, alkyl and aryl and R.sup.6 is a divalent linking group
and x and y are each independently selected from an integer from
about 2 to about 15.Iaddend..
2. The composition of claim 1 wherein said polymer is a compatible
polymer blend comprising:
(a) cellulose nitrate; and
(b) a hydrophobic acrylate polymer, wherein said polymer blend has
a sufficient amount of the acrylate polymer so as to have a glass
transition temperature of at least about 50.degree. C. and a
sufficient amount of cellulose nitrate so as to be resistant to
chlorinated hydrocarbon solvents. .[.3. A composition comprising a
blend of a major amount of a polymer or polymer blend and a minor
amount of a crosslinked member of the group consisting of a
hydroxy-terminated polysiloxane of the general structure: ##STR5##
wherein each of R.sup.1 and R.sup.2 is independently selected from
hydrogen, alkyl and aryl and w is an integer from about 100 to
about 2500 and a graft hydroxy functionalized polysiloxane having
the general structure: ##STR6## wherein R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 are each independently selected from hydrogen,
alkyl and aryl and R.sup.6 is a divalent linking group and x and y
are each independently selected from an
integer from about 2 to about 15..]. 4. A composition comprising a
solvent, a polymer, a silicone polycarbinol, a multifunctional
crosslinking reagent and a catalyst to catalyze the crosslinking of
the
silicone polycarbonol by the crosslinking reagent. 5. An element
comprising a support having thereon a layer comprising a blend of a
major amount of a polymer or polymer blend and a minor amount of a
crosslinked
silicone polycarbinol. 6. The element of claim 5 wherein said
polymer is a compatible polymer blend comprising:
(a) cellulose nitrate; and
(b) a hydrophobic acrylate polymer, wherein said polymer blend has
sufficient amount of the acrylate polymer so as to have a glass
transition temperature of at least about 50.degree. C. and a
sufficient amount of cellulose nitrate so as to be resistant to
chlorinated hydrocarbon
solvents. 7. The element comprising a support having thereon a
layer comprising a blend of a major amount of a polymer or polymer
blend and a minor amount of crosslinked member of the group
consisting of a hydroxy-terminated polysiloxane of the general
structure: ##STR7## wherein each of R.sup.1 and R.sup.2 is
independently selected from hydrogen, alkyl and aryl and w is an
integer from about 100 to about 2500 and a graft hydroxy
functionalized polysiloxane having the general structure: ##STR8##
wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 are each
independently selected from hydrogen, alkyl and aryl and R.sup.6 is
a divalent linking group and x and y are each independently
selected from an integer from about 2 to about 15.
Description
FIELD OF THE INVENTION
The present invention relates to polymer compositions which have a
low coefficient of friction.
DESCRIPTION RELATIVE TO THE PRIOR ART
It is well known in the art that many polymers have greater than
desired coefficient of friction. The high coefficient of friction
of these polymers limits their usefulness since they frequently are
not useful in contact with other components, such as, machine
components. It is well known to reduce the coefficient of friction
of certain polymers by copolymerizing into the polymer structure a
minor amount of a silicone polycarbinol. Alternatively, the
coefficient of friction of certain polymers is reduced by simply
blending the silicone polycarbinol with the polymer.
Both of these approaches to reducing the coefficient of friction
have disadvantages. If the silicone polycarbinol is copolymerized
with other monomers so as to provide a polymer with low coefficient
of friction, the formulation of special polymers which are
inconvenient and expensive is required. Further, not all polymers
can be modified in this manner since it must be possible to
copolymerize the silicone compound with the monomers which make up
the polymer. If the silicone polycarbinol is blended with an
already polymerized polymer, the composition does indeed have a low
coefficient of friction; however, the low coefficient of friction
is lost if the composition is subjected to organic solvent since
the silicone polycarbinol is leached from the composition by such
treatment.
Photographic elements which are used in motion pictures are cleaned
using chlorinated hydrocarbon solvents. In addition, the elements
are generally duplicated in what is known in the art as a "wet
gate" printer. In a wet gate printer, the printing gate is
constructed so that the photographic element to be duplicated is
immersed in a chlorinated hydrocarbon solvent during the
duplicating exposure. A useful base side protective coating for
this type of element must be resistant to chlorinated hydrocarbon
solvents.
One approach to providing both low coefficient of friction and
abrasion resistance is described in U.K. Patent application No.
2,016,167. This reference discloses a complicated blend including a
polymer, an epoxy silane for providing abrasion resistance, a
silicone fluid for low coefficient of friction and a catalyst for
the epoxy silane. Abrasion resistance is provided by forming an
extremely tough film in situ by catalyzing the polymerization of
the epoxy silane. The low coefficient of friction is provided by
the silicone fluid which optionally is a silicone polycarbinol.
Unfortunately, this composition also suffers from the disadvantage
that the low coefficient of friction is lost when the composition
is subjected to chlorinated hydrocarbon solvents, such as when
subjected to cleaning or wet gate printing. No suggestion as to how
to overcome this problem is made in this reference.
It is readily apparent that there is a continuing need for polymer
compositions which have a low coefficient of friction. The need is
particularly acute for polymer compositions which are subjected to
hydrocarbon solvents, such as, chlorinated hydrocarbon solvents,
during use.
SUMMARY OF THE INVENTION
I have found that the coefficient of friction of a polymer
composition is significantly reduced by incorporating into the
composition a crosslinked silicone polycarbinol. The coefficient of
friction of such a composition is not affected by contact with
chlorinated hydrocarbon solvents. Further, virtually any polymer or
blend of polymers is useful in the blend of the present invention
and thus the polymer compositions of the present invention are
simply and economically adapted to a variety of uses.
Thus, in one aspect of the present invention, there is provided a
composition comprising a blend of at least 80 percent by weight of
a solid or film-forming polymer and at least 0.35 weight percent of
a crosslinked silicone polycarbinol.
The composition of the present invention is particularly useful as
a coating for an element. Thus, in another aspect of the present
invention, there is provided an element comprising a support having
thereon a layer comprising the described blend.
In yet another aspect of the present invention there is provided an
element which is particularly useful as a motion picture
photographic element. Thus, there is provided a photographic
element comprising a support having on one side thereof a
hydrophilic radiation-sensitive layer and on the other side
thereof, as the outer-most layer, a layer comprising a blend as
described.
In a particularly preferred embodiment the cellulose
nitrate-hydrophobic polymer blends of U.S. Pat. No. 4,431,727 are
modified by the incorporation of the crosslinked silicone
polycarbinols as described. The resulting composition provides an
organic solvent resistant overcoat layer for the photographic
element which has a low coefficient of friction, which is capable
of chemically isolating an underlying antistatic layer and which is
extremely abrasion resistant.
DETAILED DESCRIPTION OF THE INVENTION
The compositions of the present invention include a crosslinked
silicone polycarbinol. The crosslinked compound is formed by
reacting a silicone carbinol oligomer with a suitable
multifunctional crosslinking reagent. Useful silicone carbinols
include hydroxy terminated polysiloxanes selected from the group
consisting of siloxanes of the general structure: ##STR1## wherein
each of R.sup.1 and R.sup.2 is independently selected from
hydrogen, alkyl such as methyl, ethyl or isopropyl and aryl such as
phenyl including substituted alkyl and aryl, for example tolyl,
xylyl, benxyl and phenethyl; and w is an integer from about 100 to
about 2500 and graft hydroxy functionalized polysiloxanes having
the general structure: ##STR2## wherein R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 are each independently selected from hydrogen,
alkyl and aryl as defined above and R.sup.6 is a divalent linking
group such as methylene, ethylene and butylene and x and y are each
independentely selected from an integer from about 2 to about
15.
As noted, the crosslinked silicone polycarbinol is formed by
reacting a silicone carbinol with a suitable multifunctional
crosslinking reagent. Useful crosslinking reagents include any
multifunctional compound which is capable of reacting with the
hydroxy group of the silicone polycarbinol generally in the
presence of a catalyst. Particularly useful multifunctional
compounds of this type include melamines such as
hexamethoxymethylmelamine and partially methylated melamine
formaldehyde: glycoluril containing compounds such as Cymel
1170.RTM. and Cymel 1172.RTM. (American Cyanamide Company). Other
useful multifunctional crosslinking reagents include methylol
phenols such as 2-methylolphenol, 2,4,6-trimethylolphenol and
methylolcresol; acyl halides such as terephthaloyl chloride,
isovaleroyl chloride and sebacoyl chloride; acid anhydrides such as
phthalic anhydride, maleic anhydride and pyromellitic dianhydride;
and isocyanates such as toluene diisocyanates, isophorone,
diisocyanate and 4,4'-methylene bis(cyclohexane isocyanate).
Crosslinking of the silicone polycarbinol occurs spontaneously as
solvent is removed from a mixture which contains the solvent,
polymer or polymer blend, silicon polycarbinol, multifunctional
crosslinking reagent and catalyst. While not necessary, the
catalyst is optionally removed from the composition after or during
the removal of the solvent.
In addition to the crosslinked silicone polycarbinol, the
compositions of the present invention include a solid or
film-forming polymer. A wide variety of polymer or polymer blends
are useful with the described crosslinked silicone polycarbinol. It
is only necessary that the composition form a single phase mixture.
Useful polymers include thermoplastic polymers that are soluble in
common solvents including, for example, acrylic ester polymers and
copolymers of acrylic esters with acrylic acids. Examples of these
polymers include poly(methyl acrylate), poly(methyl methacrylate)
and poly(methyl methacrylate-co-acrylic acid). Other useful
polymers include polyvinyl esters such as poly(vinyl acetate);
cellulose esters such as cellulose acetate, cellulose
acetate/butyrate; cellulose ethers such as methyl cellulose, vinyl
chloride copolymers; polyesters; and polyurethanes. Other useful
polymers include cellulose nitrate, poly-styrene, and polyvinyl
pyrrolidone.
The compositions of the present invention include a major amount of
the solid or film-forming polymer and a minor amount of the
crosslinked silicone polycarbinol. By major amount is meant that
the composition includes 80 percent or more of the described
polymer and, corresponding, 20 percent or less of the described
crosslinked silicone polycarbinol. More particularly, the useful
concentration of silicone polycarbinol in the coating composition
ranges from about 0.25 to about 10 weight percent of the final
composition. In preferred embodiments, the range of silicone
compound is between 0.5 and 3 weight percent. The amount of
crosslinking reagent varies with the amount of silicone
polycarbinol. Generally, it is desirable but not necessary to
include a sufficient amount of the crosslinking reagent to
crosslink substantially all of the silicone compound which is
included in the composition. Generally, the crosslinking reagent is
in the range of about 0.1 to about 10 weight percent of the final
dried composition and, preferably, in the range of about 0.5 to 5
weight percent. Thus, the weight percentage of the crosslinked
silicone polycarbinol, including the crosslinking reagent, is at
least 0.35 percent up to 20 percent.
The nature and amount of catalyst used in the composition of the
present invention in order to catalyze the crosslinking of the
silicone polycarbinol by the crosslinking reagent also varies
depending on the specific silicone compound chosen and its
concentration in the composition. In preferred embodiments, the
reaction is catalyzed by sulfuric acid which can be present in the
final composition in an amount between 0.5 and 2 weight percent.
Other acids, such as phosphoric, hydrochloric and p-toluenesulfonic
acid are also useful catalysts and are used in similar
concentrations.
In particularly preferred embodiments the polymer compositions
include a blend of cellulose nitrate and a hydrophobic polymer as
described in U.S. Ser. No. 388,322, filed of even date herewith,
issued as U.S. Pat. No. 4,431,727 entitled PROTECTIVE OVERCOATS FOR
PHOTOGRAPHIC ELEMENTS, referenced above. These compositions provide
protective overcoat layers for photographic elements which are
relatively resistant to abrasion, resistant to static charging,
resistant to ferrotyping, capable of chemically isolating the
antistatic layer which is desirably coated on the element, are
resistant to chlorinated hydrocarbon solvents, and have desirably
low coefficient of friction.
The preferred polymer blend comprises a compatible blend of:
(a) cellulose nitrate and
(b) a hydrophobic polymer
wherein the blend has a sufficient amount of hydrophobic polymer so
as to have a glass transition temperature of at least 50.degree. C.
and a sufficient amount of cellulose nitrate so as to be resistant
to chlorinated hydrocarbon solvents and photographic processing
compositions.
The layers containing the polymer blends of the present invention
have a glass transition temperature which is at least about
50.degree. C. Measurement of the glass transition temperature is
made by methods which are well-known in the art. (See, for example,
Techniques and Methods of Polymer Evaluation, Vol. 1, Marcel
Dekker, Inc., New York, N.Y.).
The polymer blend contains sufficient cellulose nitrate so as to
provide resistance to chlorinated hydrocarbon solvents and
photographic processing compositions. By "resistance to chlorinated
hydrocarbon solvents" is meant that the coated and dried layer is
substantially unaffected when contacted with the described solvent.
The determination of whether a particular blend is resistant to
chlorinated hydrocarbon solvents is made by the following simple
experiment. The blend of interest is coated on a suitable support
such as a glass slide or a cellulose acetate support and allowed to
dry. A sample of the element is then passed through an
ultrasonically agitated bath of 1,1,1-trichloroethane at
105.degree. F. such that is residence time in the bath is about 15
seconds. The coating is then visually examined for the effect of
this treatment. If the layer remains intact during this treatment,
it is considered to be resistant to chlorinated hydrocarbon
solvents. Generally the same amount of cellulose nitrate also
provides resistance to photographic processing compositions. That
is, the layer is capable of chemically isolating underlayers from
high pH solutions. It is desirable to maintain the amount of
cellulose nitrate at the lowest level possible consistant with
maintaining solvent and processing composition resistance because
cellulose nitrate is extremely flammable. The preferred amount of
cellulose nitrate in the blend is between 5 and 70 percent by
weight.
The particularly preferred compositions of the present invention
comprise a compatible blend of cellulose nitrate and an hydrophobic
polymer. By "compatible" is meant that a layer cast from a
homogeneous solution of the blend exhibits substantially no phase
separation and is substantially clear. Cellulose nitrate is capable
of forming a compatible blend with a wide variety of hydrophobic
polymers. Whether a particular blend is compatible is determined by
simple experiment. The polymer blend in question is dissolved in a
solvent or solvent mixture and cast on a glass slide. A solvent
mixture of acetone and 2-methoxyethanol (95/5 by volume) is useful.
The acetone is a true solvent for cellulose nitrate and the
2-methoxyethanol is present to reduce the drying rate. The cast
layer is allowed to dry and is visually observed. The blend is
considered compatible if little or no light scattering is detected
visually by viewing the layer at low angles of light incidence.
This is an art-recognized method for determining polymer blend
compatibility. (See R. J. Peterson et al, "Recent Advances in
Polymer Compatibility", ACS Polymer Preprints, pages 385-391,
1969.)
Cellulose nitrate is the reaction product of cellulose with nitric
acid. Cellulose is composed of a large number of
.beta.-anhydroglucose units. The glucose units have three hydroxyl
groups and are joined together by acetyl linkages. Various grades
of cellulose nitrate are characterized by the degree of
substitution by nitro groups of the hydroxyl groups in the
anhydroglucose units and by the degree of polymerization. Cellulose
nitrates which are useful in the present invention include any of a
wide variety of cellulose nitrates including those which are
commercially available. Useful cellulose nitrates include RS.TM.
cellulose nitrates, as well as AS.TM. and SS.TM. cellulose
nitrates. RS.TM. cellulose nitrates, for example, has a nominal
degree of substitution which corresponds to a nitrogen content of
about 12 percent. The viscosity of a particular cellulose nitrate
is related to its degree of polymerization and is expressed in
terms of either centipose or the time expressed in seconds for a
metal ball of specified size and density to fall through a measured
distanct in a solution of the cellulose nitrate. For the purposes
of the present specification, the viscosity in seconds is the time
required for a 1/32-inch (0.08 cm) steel ball to fall 2 inches
(5.08 cm) in a 12.2 percent solution of the cellulose nitrate in
acetone at 25.degree. C. This corresponds to the ASTMD1343-56
procedure. Reference is made to H. M. Sperlin et al, j"Cellulose
and Cellulose Derivatives", High Polymers, Vol V, 2nd edition, part
3, Interscience, New York, 1955.
The other component of the compatible polymer blend of the
preferred layers of the present invention is a hydrophobic polymer.
By "hydrophobic" is meant substantially water-insoluble and
substantially not swellable in water. In preferred embodiments, the
polymer is an acrylate polymer, i.e., either a homopolymer of an
acrylate monomer or a copolymer which comprises at least about 10
weight percent of an acrylate monomer. The acrylate polymer or
other hydrophobic polymer has a glass transition temperature such
that, when it is mixed with the desired amount of the cellulose
nitrate, it provides a layer having a glass transition temperature
of at least about 50.degree. C. Acrylate monomers are esters of
ethylenically unsaturated mono or dicarboxylic acids. Useful
monomers include methyl methacrylate, ethyl acrylate and diethyl
methylenemalonate. The comonomer of the acrylate copolymers which
are useful in the blends of the present invention are any of a wide
variety of monomers. Useful monomers include copolymerizable,
.alpha.,.beta.-ethylenically unsaturated monomers. Useful monomers
of this type include ethylene, propylene, 1-butene, isobutene,
2-methylpentene, 2-methylbutene, 1,1,4,4-tetramethylbutadiene,
styrene and .alpha.-methylstyrene; and monoethylenically
unsaturated esters of aliphatic acids such as vinyl acetate,
isopropenyl acetate and allyl acetate.
Useful hydrophobic acrylate polymers include poly(methyl
methacrylate), poly(butyl acrylate-co-methyl methacrylate),
poly(vinyl acetate-co-methyl methacrylate), poly(ethyl
methacrylate) and poly(styrene-co-methyl methacrylate). Other
nonacrylate polymers which are useful in the blend include
poly(vinyl acetate) and cellulose acetate butyrate.
The preferred protective overcoat layers of the present invention
are coated from a solvent solution of the polymers. The solvent
chosen is capable of dissolving both components of the blend as
well as the silicone polycarbinol. Frequently, it is desirable to
use a solvent mixture in order to adjust the viscosity of the
coating composition, to economize on solvent cost or for some other
purpose. Cellulose nitrate is soluble in a variety of solvents
including ketones, esters, amides and nitroparaffins. Certain
alcohols are also solvents for nitrocellulose, particularly when
used in admixture with other solvents. Useful alcohol solvents
include isopropanol and 2-methoxyethanol. If a solvent mixture is
used, the cosolvent is any of a wide variety of solvents. Useful
cosolvents include acetone, ethyl acetate and methyl ethyl ketone.
Useful diluents include liquid hydrocarbons, either aromatic or
aliphatic, such as 1,1,1-trichloroethane, dichloromethane and
toluene.
The described polymer blends are coated to produce the protective
layers of the present invention using any suitable method. For
example, the compositions are coated by spray coating, fluidized
bed coating, dip coating, doctor-blade coating or extrusion hopper
coating.
The weight percent solids in the coating composition which is
useful to form the layers of the present invention varies widely.
The percent solids, along with the method of coating, has a
substantial influence on the coverage of the layer which results
from coating the composition. A useful range for the weight percent
solids in the coating composition depends on the specific members
of the polymer blend and the solvents chosen and is usually between
about 1 percent to about 10 percent.
The protective overcoat layers of the present invention are
particularly useful over antistatic layers on the base side of a
silver halide photographic element. Useful antistatic layers
include those described in U.S. Pat. Nos. 3,399,995, 3,674,711 and
3,011,918 which relate to layers containing water-dispersible,
particulate polymers. One particularly preferred antistatic layer
is described in U.S. Pat. No. 4,070,189 which relates to the use of
water-dispersible, particulate vinylbenzyl quaternary ammonium or
phosphonium salt polymers. Another useful antistatic layer of this
type is described in U.S. Pat. No. 4,294,739. Another class of
particularly preferred antistatic layers consists of the
polyaniline salt-containing layers described, for example, in U.S.
Pat. Nos. 3,963,498 and 4,237,194.
Photographic elements comprise a support having thereon at least
one radiation-sensitive layer. The protective layer of the present
invention is coated as the outermost layer on the base side of the
photographic element. The other side of the photographic element,
commonly referred to as the emulsion side, has as its outermost
layer a hydrophilic layer. This hydrophilic layer is either the
radiation-sensitive layer itself such as one containing silver
halide or an overcoat layer which is hydrophilic so as to
facilitate processing of the element. This outermost hydrophilic
layer optionally contains a variety of addenda such as matting
agents, antifoggants, plasticizers and haze-reducing agents. The
outermost hydrophilic layer comprises any of a large number of
water-permeable hydrophilic polymers. Typical hydrophilic polymers
include gelatin, albumin, poly(vinyl alcohols) and hydrolyzed
cellulose esters.
Photograhic silver halide radiation-sensitive layers are well-known
in the art. Such layers are more completely described in Research
Disclosure, Dec., 1978 pages 22-31, item 17643. Research Disclosure
is published by Industrial Opportunities, Ltd, Homewell, Havant,
Hampshire, PO9 1EF, United Kingdom.
The photographic elements of the present invention include a
photographic support. Useful supports include those described in
paragraph XVII of the above-identified Research Disclosure.
Particularly useful supports include cellulose acetate and
poly(ethylene terephthalate).
The following examples are presented to illustrate the practice of
the present invention.
EXAMPLE 1
Poly(methyl methacrylate) [Elvacite.RTM. 2010, 1.5 g] and cellulose
nitrate [RS-1/2 second grade, 1.5 g] were dissolved in 65 mL
acetone and 30 mL 1,1,1-trichloroethane. To this solution was added
3.0 mL of a 2 percent (wt./vol.) solution of L-540.RTM. silicone
fluid (Union Carbide Corp.) in acetone, 1.5 mL of 10 percent
(wt./vol.) Cymel 303.RTM. (hexamethoxymethylmelamine; American
Cyanamid) in acetone, and 0.6 mL of a 5 percent (wt./vol.) solution
of H.sub.2 SO.sub.4 in isopropanol. The resulting composition was
coated on cellulose acetate support to give, upon removal of the
solvent, a layer approximately 0.6 .mu.m thick. The abrasion
resistance of the layer was tested by a single-arm scratch test,
using, for comparison, the polymer combination alone, and the
polymer combination with silicone fluid but without crosslinking
agent and acid catalyst. In the single arm scratch test, the film
is scratched with a ballpoint stylus under increasing loads. The
film is evaluated by projecting the film on a screen at a distance
of 4'. The scratch resistance is subjectively rated by an
experienced observer as the number of grams required to produce a
visible scratch. A plow is a severe scratch including gross
displacement of scratched material. Scratch data are presented
below.
______________________________________ First First Line Plow
______________________________________ (1) Polymer blend + L-540 90
gM. + >140 g Cymel 303 .RTM. + H.sub.2 SO.sub.4 (2) Polymer
blend + L-540 .RTM. 90 g >140 g (Comparison) (3) Polymer blend
only (Comparison) 60 g 100 g
______________________________________
It is clear from these data that the scratch resistance of the
polymer coating has been greatly improved by the silicone
addition.
The same three films were then passed through a simulated
film-cleaning device in which the films were treated with
ultrasonically-agitated 1,1,1-trichloroethane at 105.degree. F.
(40.degree. C.) for about 5 seconds. The abrasion resistance was
again evaluated by the single-arm scratch test.
______________________________________ Projected at 4 feet First
First Line Plow ______________________________________ (1) Polymer
blend + L-540 .RTM. + 90 g >140 g Cymel 303 .RTM. + H.sub.2
SO.sub.4 (2) Polymer blend + L-540 .RTM. 60 g 100 g (Comparison)
(3) Polymer blend only (Comparison) 55 g 100 g
______________________________________
It is clear from these data that the new coating compositions
maintain their enhanced abrasion resistance after treatment with
the chlorinated solvent in a film-cleaning device. Films prepared
with the silicone fluid alone, while providing an initial
enhancement, did not maintain their improved abrasion resistance
after treatment with the cleaning solvent.
EXAMPLE 2
Poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) (99:1
wt.), 3.0 g, was dissolved in 95 mL of 1,2-dichloropropane. To this
solution was added 3.0 mL of a 2 percent (wt./vol.) solution of
DC-1248.RTM. silicone fluid (Dow Corning Corp.) in acetone, 1.5 mL
of 10 percent (wt./vol.) Cymel 303.RTM. in acetone, and 0.6 mL 5
percent (wt./vol.) H.sub.2 SO.sub.4 in isopropanol. The resulting
composition was coated onto a cellulose acetate support to give,
upon removal of the solvent, a layer approximately 0.6 .mu.m thick.
Layers with the polymer alone, and the polymer with silicone fluid
but without crosslinking agent and acid catalyst, were prepared in
the same manner for comparison. The three films were passed through
the simulated film cleaner, as in Example 1, and the abrasion
resistance was evaluated using the single-arm scratch test.
______________________________________ Before Cleaning After
Cleaning First First First First Line Plow Line Plow
______________________________________ (1) Polymer + 110 g >140
g 80 g >140 g DC-1248 .RTM. + Cymel 303 .RTM. + H.sub.2 SO.sub.4
(2) Polymer + 110 g >140 g 50 g 80 g DC-1248 .RTM. (Comparison)
(3) Polymer only 50 g 90 g 60 g 95 g (Comparison)
______________________________________
Both the improvement in abrasion resistance and the maintenance of
the improvement after solvent cleaning are clearly demonstrated by
these data for the case in which silicone fluid crosslinking
reagent and acid catalyst are added to the polymer so that the
silicone polycarbinol is crosslinked.
The invention has been described in detail with particular
reference to preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *