U.S. patent number 3,552,315 [Application Number 04/526,988] was granted by the patent office on 1971-01-05 for offset master for imaging by diffusion transfer with nucleating agent, cadium salt and a salt of zirconium, thorium or titanium.
This patent grant is currently assigned to A. B. Dick Company. Invention is credited to Mary K. Ormsbee.
United States Patent |
3,552,315 |
Ormsbee |
January 5, 1971 |
OFFSET MASTER FOR IMAGING BY DIFFUSION TRANSFER WITH NUCLEATING
AGENT, CADIUM SALT AND A SALT OF ZIRCONIUM, THORIUM OR TITANIUM
Abstract
The preparation of an offset master for imaging to provide an
oleophilic ink receptive image by diffusion transfer from an
exposed silver halide negative in which the offset master has a
surface which is water insoluble, water receptive, hydrophilic and
lithographic and in which the lithographic surface is provided with
one or more coatings providing the combination of a nucleating
agent, a water soluble salt of cadmium and a water soluble salt of
a metal selected from the group consisting of zirconium, thorium
and titanium and in which the cadmium salt may be placed in whole
or in part with an antioxidant.
Inventors: |
Ormsbee; Mary K. (River Forest,
IL) |
Assignee: |
A. B. Dick Company (Niles,
IL)
|
Family
ID: |
27062280 |
Appl.
No.: |
04/526,988 |
Filed: |
February 14, 1966 |
Current U.S.
Class: |
430/204; 101/462;
430/209; 101/459 |
Current CPC
Class: |
G03F
7/07 (20130101) |
Current International
Class: |
G03F
7/07 (20060101); B41n 001/04 (); B41n 001/12 ();
G03o 005/54 () |
Field of
Search: |
;96/29,76
;101/456,466,149.2,453,459,462 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
565,696 |
|
Jul 1960 |
|
BE |
|
202,937 |
|
Aug 1954 |
|
AU |
|
830,623 |
|
Mar 1960 |
|
GB |
|
856,770 |
|
Dec 1960 |
|
GB |
|
Primary Examiner: Lesmes; George F.
Assistant Examiner: Brammer; J. P.
Claims
I claim:
1. An offset master for imaging to provide an oleophilic ink
receptive image by diffusion transfer from an exposed silver halide
negative comprising a base sheet having a water insoluble, water
receptive, hydrophilic, lithographic surface, said master having on
the lithographic surface the combination of a nucleating agent for
silver halide a water soluble salt of cadmium as a component
separate and apart from the nucleating agent and present in an
amount within the range of 0.01 to 0.5 parts by weight of the
cadmium salt to 1 part by weight of the nucleating agent, and a
water soluble salt of a metal selected from the group consisting of
zirconium, thorium and titanium as a component separate and apart
from the nucleating agent and present in an amount within the range
of 1 to 8 parts by weight of the metal salt to 1 part by weight of
the nucleating agent.
2. An offset master as claimed in claim 1 in which the nucleating
agent comprises a stannous halide.
3. An offset master as claimed in claim 2 in which the stannous
halide, the zirconium salt and the cadmium salt are present in the
same coating.
4. An offset master as claimed in claim 2 in which the stannous
halide, zirconium salt and cadmium salt are present in separate
coatings.
5. An offset master as claimed in claim 2 in which the salts are
present in the ratio of 1 part by weight of the stannous salt to
1.7 to 3.5 parts by weight of zirconium salt and 0.02 to 0.2 parts
by weight of cadmium salt.
6. An offset master as claimed in claim 2 in which the salts are
present on the lithographic surface in a coating weight within the
range of 0.1 to 4 grams per square meter.
7. An offset master as claimed in claim 2 in which the salts are
present on the lithographic surface in a coating weight of 0.5 to 3
grams per square meter.
8. An offset master as claimed in claim 1 which includes a film of
plastic material as a cover over the coated lithographic surface.
Description
This invention relates to the art of offset or lithographic
duplication and more particularly to a new and improved offset
master and method for the preparation of same.
Offset masters for offset copy work are generally of the direct
image type wherein the hydrophilic lithographic surface of the
master is imaged directly by the application of an oleophilic ink
receptive imaging material, as by inscribing with a crayon or ink,
or by transfer from a carbon sheet in response to compression or
impact by stylus, typewriter key, die impression or the like. When
mounted on a lithographic press and wet with an oleophilic ink
composition and an aqueous repellent, the nonimaged portions of the
master accept the aqueous repellent while the ink composition is
taken up by the oleophilic ink receptive imaged portions of the
master for subsequent transfer either directly to copy sheets
brought into surface contact with the inked master or indirectly to
an offset blanket from which the image is transferred to copy
sheets.
When it is desirable to prepare an offset master imaged from an
original, it has been necessary to make use of an indirect offset
master, more often referred to as a photolithographic master. A
master of the type described has been produced wherein the
hydrophilic lithographic surface is overcoated with a water
soluble, resin forming, light sensitive diazo compound in which a
negative transparency is first formed of the original and then the
diazo light sensitive coating is exposed to the developed negative
transparency to resinify the diazo compound in the exposed areas
while the portions of the light sensitive diazo coating in the
unexposed areas are removed by washing to produce an imaged
photolithographic plate. Others of the photolithographic masters
are somewhat similar in construction in that the master sheet is
presensitized with a light sensitive material that is convertible
to an ink receptive imaging material upon exposure to light. Such
presensitized photolithographic masters are subject to a number of
deficiencies including high cost, short shelf life, the need to
make use of specialized equipment and materials, and the need to
prepare a negative transparency by conventional photographic
technique.
More recently lithographic or offset masters capable of being
imaged by diffusion transfer technique from an exposed but
underdeveloped silver halide negative have been produced in which
the hydrophilic, lithographic surface is provided with a nucleating
or fogging agent for reducing silver halide to an ink receptive,
water repellent silver image whereby, when the master sheet is
brought into contact with the exposed silver halide negative wet
with a silver halide solvent and developer, the silver halide in
the unexposed portions of the negative transfer by diffusion to the
surface of the master where the silver halide or complex formed
thereof is reduced to a silver, ink receptive, water repellent
imaging material on the hydrophilic, water receptive lithographic
surface to produce the master having an image corresponding to the
original.
The diffusion transfer reversal technique makes use of equipment
and materials which are of low cost and which have heretofore found
widespread use in single copy diffusion transfer reversal processes
commonly employed in the field. The diffusion transfer process also
eliminates the need for the preparation of a negative transparency
and the exposure of the negative transparency to a presensitized
master is also completely eliminated.
To the present, the diffusion transfer reversal process for
preparation of an imaged lithographic master from an original has
been limited to use of a master sheet formed of a metal base such
as aluminum, having its surface treated as by silicating, brushing,
anodizing, or the like, to render the surface water receptive,
hydrophilic and lithographic. It is desirable to expand the
lithographic process to enable use of lower cost coated paper
lithographic masters which can be imaged by diffusion transfer
technique and it is also desirable to provide means for improving
the definition of the image formed on the lithographic surface as
by providing a desired differential between the hydrophilic, water
receptivity of the lithographic surface and the ink receptivity and
water repellency of the image that is formed thereon by the
deposited silver and it is a related object of the invention to
provide a lithographic master embodying such improvements and to
provide a method for producing same.
Another object of this invention is to produce and to provide a
method for producing an offset or lithographic master which can be
fabricated of a paper or film base as well as of an amphoteric
metal such as aluminum, which can be imaged directly or indirectly
by diffusion transfer from an exposed silver halide negative or by
direct application of silver halide to form the image on the
lithographic surface, which provides a desirable balance between
the hydrophilic nonimaged portion and the oleophilic imaged portion
of the master, which need not be presensitized and therefore is not
sensitive to light, and which is capable of use to produce a large
number of copies of good quality by conventional lithographic
duplicating technique.
These and other objects and advantages of this invention will
hereinafter appear and for purposes of illustration, but not of
limitation, embodiments of the invention are shown in the
accompanying drawings, in which:
FIG. 1 is a perspective view partially in section of a lithographic
master prepared in accordance with the practice of this
invention;
FIG. 2 is a sectional elevational view of a modification in a
lithographic master prepared in accordance with the practice of
this invention;
FIG. 3 is a sectional elevational view showing the arrangement of
elements including the master shown in FIG. 1 and an exposed silver
halide negative in position to form the image by diffusion transfer
on the lithographic surface;
FIG. 4 is a perspective view partially in section of the imaged
master produced with the master of FIG. 1; and
FIG. 5 is a perspective view partially in section of the master of
FIG. 1 having a protective plastic film.
The offset or lithographic master embodying the features of this
invention comprises a flexible base sheet 10 having a water
insoluble, water receptive, ink repellent, lithographic surface 12
which is overcoated with one or more coatings 14 containing a
silver halide fogging or nucleating agent, a zirconium salt and a
cadmium salt as the essential components, and desirably though not
essentially, a removable protective film 16 of plastic material
covering the coated surface.
As the base sheet 10, use can be made of a foil of an amphoteric
metal, such as aluminum, zinc or copper, in which the surface of
the metal such as aluminum is rendered hydrophilic and lithographic
by treatment such as brushing, anodizing, or preferably by
silicating with a soluble silicate solution. Instead, use can be
made of a paper base sheet 10 which is resinous impregnated or
treated with a resinous material for high wet strength and which is
provided with a continuous water insolubilized, water receptive,
ink repellent, hydrophilic lithographic coating 12 formulated of a
hydrophilic colloid of resin as a binder and a filler such as zinc
oxide, satin white, clay and the like. Suitable binders comprise
casein, starch, carboxymethylcellulose, polyacrylic acid, polyvinyl
acetate, alginates, polyvinylpyrrolidone, and polyvinyl alcohol,
reference being made to the following patents for illustrations of
coated paper lithographic plates formulated of the above materials,
namely: Worthem U.S. Pat. No. 2,534,650 (casein); Van Dusen U.S.
Pat. No. 2,542,784 (carboxymethylcellulose); Ensink U.S. Pat. No.
2,806,424 (alignates); Beatty et al. U.S. Pat. No. 2,760,431 (zinc
polyacrylate); Toland U.S. Pat. No. 2,230,982 (polyvinyl
alcohol).
The base sheet is formed with openings 18 at one end for use in
mounting the master onto the plate cylinder of a conventional
planographic printing press for use in the production of multiple
copies. Instead of openings for mounting on the press, other means
on the end portion of the master may be provided for clamping the
master onto the plate cylinder.
As the nucleating agent, it is preferred to make use of a stannous
halide, such as stannous chloride, stannous bromide, stannous
fluoride and the like. Though less desirable in the combination
described, use can be made of other silver halide nucleating
agents, sometimes referred to as fogging agents, as described in
U.S. Pat. No. 2,352,014 and including colloidal silver and the
like.
The zirconium salt comprises a water soluble salt of zirconium such
as zirconyl methylate, zirconyl acetate, zirconyl propionate,
zirconyl chloride, zirconyl nitrate, and other zirconyl halides and
the like. While less desirable than the zirconyl salts and while
not equivalent thereto in the described system, the zirconium salts
can be replaced in whole or in part by the corresponding water
soluble salts of thorium or titanium.
As the cadmium salt, use can be made of a water soluble salt of
cadmium such as an organo cadmium salt represented by cadmium
acetate or an inorganic salt such as cadmium chloride, cadmium
bromide, cadmium nitrate, or other cadmium halide and the like. The
cadmium salt can be replaced by an antioxidant but when use is made
of an antioxidant it is preferred to make use of such antioxidant
in combination with the cadmium salt. Representative of the
antioxidants which may be employed are: ##SPC1##
The materials are formulated into a coating composition in the
ratio of 1 part by weight stannous salt per 1.0 to 8 parts by
weight of the zirconium salt and 0.01 to 0.5 parts by weight of the
cadmium salt, and preferably in an amount within the range of 1
part by weight of the stannous salt to 1.7 to 3.5 parts by weight
of the zirconium salt and 0.02 to 0.2 parts by weight of the
cadmium salt. The materials can be formulated into a coating
composition in which the materials are present in an amount to
provide a solids content of 1 to 15 percent by weight and
preferably 2 to 8 percent by weight. The composition is applied in
coating weights within the range of 0.1 to 4 grams per square
meter, and preferably in an amount within the range of 0.5 to 3
grams solids per square meter.
Instead of applying the materials from a single coating
composition, the three essential components can be applied in
corresponding amounts in separate coatings to provide one coating
20 containing the cadmium salt, with or without an antioxidant
additive, and the other coating 22 containing the zirconium,
thorium or titanium salt, and a third coating containing the
fogging or nucleating agent, or the materials may be formulated
into two coating compositions in which the components are present
in the various combinations.
Application onto the lithographic surface can be made by
conventional coating processes, such as by spray coating, roller
coating, flow coating and the like, followed by air drying or
drying at elevated temperature, such as up to 200.degree. F.
The following are examples of compositions which may be applied as
coatings onto the lithographic surface in the preparation of
diffusion transfer offset masters embodying the features of this
invention: ##SPC2## ##SPC3##
An aluminum base sheet 10 having a silicated water receptive,
lithograph surface 12, prepared in accordance with the teachings of
the Jewett et al. U.S. Pat. No. 2,714,066, is roller coated with
the composition of example 1 to provide a coating weight of about
0.75 grams per square meter. The applied coating 14 is either air
dried or drying can be accelerated by heating to an elevated
temperature of about 200.degree. F. to produce the finished
master.
In the preparation of a coated paper lithographic plate embodying
the features of this invention, use is made of a coated paper
direct image plate formed of high wet strength paper base sheet 10
having a lithographic coating 12 provided thereon as described in
the Worthem U.S. Pat. No. 2,534,650, or the Van Dusen U.S. Pat. No.
2,542,784, or the Ensink U.S. Pat. No. 2,806,424, or the Beatty et
al. U.S. Pat. No. 2,760,431. The lithographic surface of the coated
paper base sheet is over coated with a composition of one of the
examples 1 to 5 applied to provide an overall coating having a
coating weight of 0.5 to 3.0 grams per square meter. The applied
coating is dried at elevated temperature within the range of
100.degree.--200.degree. F.
In the use of a plural coating process of example 6, part A is
applied first onto the lithographic surface and then dried, after
which part B is applied and dried to provide the plural coatings 20
and 22.
The shelf life of the masters prepared in accordance with the
practice of this invention can be greatly extended and improved
when the coating or coatings, applied in accordance with the
practice of this invention, is covered with a removable film 16 of
plastic material, such as a film of polystyrene, Teflon,
polyvinylidene chloride, polyvinyl chloride, chlorinated rubber and
the like.
More than one coating of the composition embodying the features of
this invention can be applied onto the lithographic surface. Such
plural coatings will enhance the protective features of one coating
for another to resist oxidation and deterioration. In such event,
the need for a protective film 16 is greatly minimized.
In use of an offset master prepared in accordance with the practice
of this invention, use is made of a negative 30 in the form of a
base sheet 32 having a light sensitive, silver halide gelatin
coating 34. Representative of suitable negatives are Gevaert GS
negative (Gevaert Photo Production of Antwerp, Belgium); Oricopy
(Oriental Photocopy Company, Tokyo, Japan), or Anken Photo Rapid
negative, of the Anken Chemical Company of the United States.
The negative 30 is exposed to the original in a conventional
photographic exposure apparatus. The exposed negative is then
brought into pressure contact with the coated surface of the master
sheet after one or both of the surfaces have been wet with a
monobath developer, as represented by the following example:
##SPC4##
The sheets can be processed through an A, B. Dick 110 Photocopier
filled with the monobath solution. In operation, the monobath
operates to form a soluble complex of the silver halide in the
unexposed portions of the negative for transfer of the complex of
silver halide by diffusion to the coated surface of the master
where the silver halide is nucleated to deposit dense masses of
silver 36 concentrated at the surface of the master to form an ink
receptive, highly hydrophobic image 38 on the lithographic
hydrophilic surface.
The formed silver image remains strongly bonded to the lithographic
surface. The imaged plate is wet with a conventional fixer or
conditioner, such as the CT offset fixer of Eastman Kodak or -
84-4966 A. B. Dick Photoplax Conditioner, which operates to make
the nonimaged areas hydrophilic and fix the image onto the master.
Thereafter the imaged master can be mounted on the plate cylinder
of a conventional lithographic press and sequentially wet with
aqueous repellent and oleophilic ink whereby the repellent wets out
the nonimaged portions of the plate while the ink wets out the
imaged portions of the plate thereby to enable production of
thousands of copies of good quality.
It will be understood that changes may be made in the details of
formulation, method of application and use without departing from
the spirit of the invention, especially as defined in the following
claims.
* * * * *