Method of making a lithographic printing plate with an ink jet fluid material

Provided is a media-ink jet fluid marking material set which comprises a media comprising a support with a hydrophilic receiving layer together with an ink jet fluid marking material which comprises a liquid carrier medium and at least one organic or transition metal complex reactive component. Upon ink jet printing and subsequent exposure to an energy source, an effective amount of an olcophilic, water-insoluble, and substantially non-metallic pattern is achieved on the hydrophilic media. Such a media-ink jet fluid marking material set can be advantageously used in the manufacture of lithographic printing plates, and provides many advantages in the manufacture of durable and water-insoluble imaging elements.

FIELD OF THE INVENTION 
This invention relates to a media-ink jet fluid set used in ink jet 
printing to produce a more durable, water-fast image, and more 
particularly, to a media-ink jet fluid set that provides an economical 
lithographic printing plate. 
BACKGROUND OF THE INVENTION 
Lithographic printing has long been the most widely used printing 
technique, especially for short to medium printing run lengths of 1,000 to 
15,000. By the term "lithographic" is meant to include various terms used 
synonymously, such as offset, offset lithographic, wet lithographic, 
planographic, and others. Most lithographic plates are still produced 
photographically. The disadvantages of this and some of the alternative 
lithographic plate materials and processes are described in U.S. Pat. Nos. 
4,958,563 and 5,487,338. 
With the advent of the computer in revolutionizing the graphics design 
process leading to printing, there have been extensive efforts to develop 
a convenient and inexpensive computer-to-plate system, particularly for 
use in lithographic printing. Many of the new computer-to-plate system are 
large, complex, and expensive. They are designed for use by large printing 
companies as a means to streamline the prepress process of their printing 
operations and to take advantage of the rapid exchange and response to the 
digital information of graphics designs provided by their customers. There 
remains a strong need for an economical and efficient computer-to-plate 
system for the many smaller printers who utilize lithographic printing. 
A number of electronic, non-impact printing systems have been investigated 
for use in making lithographic printing plates to satisfy the needs of 
these smaller printers. Foremost among these have been laser printing 
systems, for example as described in U.S. Pat. No. 5,304,443 and 
references therein. These have had some limited success, but have not been 
able to overcome the disadvantages of undesired background toner imaging, 
limitation to small sizes (approximately 11 inches by 18 inches) which are 
too small for many applications and limitation to only those flexible 
substrates such as paper and plastic films which can transport through the 
laser printers. 
Another non-impact printing system which has received attention for 
economical and convenient computer-to-plate preparation for lithographic 
printing is thermal transfer printing, for example, as described in U.S. 
Pat. No. 4,958,564. This involves the printing of a hydrophobic wax or 
resin material on to the lithographic printing blank. This approach has 
similar size and flexible substrate limitations as described above for 
laser printing. In addition, the nature of the thermal transfer process is 
very demanding on intimate contact of the wax or resin donor ribbon to the 
receiver substrate to obtain consistent image quality. For this latter 
reason especially, the low cost thermal transfer printers in wide use for 
hard copy color output printing from computers are not used to prepare 
lithographic printing plates. Instead, more expensive, specially built 
thermal transfer printers have been proposed. The only widely used 
printers for hard copy computer output that have seen some use in making 
lithographic plates are laser printers, in spite of their aforementioned 
disadvantages. 
In recent years, ink jet printers have replaced laser printers as the most 
popular hard copy output printers for computers. Some of the competitive 
advantages of ink jet printers have been low cost, reliability, and the 
ability to make color images without significantly increasing the cost of 
the printer. Both thermal ink jet and piezoelectric ink jet printing 
methods have been widely adopted for desktop computer printing. A third 
conventional type of ink jet printing, a continuous flow type method, has 
found acceptance in high quality color printing and proofing in graphics 
applications. 
In spite of the very large and rapidly growing installed base of low cost 
desktop ink jet printers as well as a large number of higher cost, larger 
size ink jet printers used in prepress proofing and in printing output, 
there has not been use of these ink jet printers to make lithographic 
printing plates. There have been some reports in the literature proposing 
the use of ink jet printers to make lithographic printing plates. In 
Japanese Kokai 62-25081, an oleophilic liquid or fluid ink was printed by 
ink jet printing on to a hydrophilic aluminum surface of a lithographic 
printing plate. Titanate or silane coupling agents were present in the 
ink. 
An ink jet printing apparatus to make lithographic printing plates is 
described in PCT WO 94/11191. It is directed to depositing hydrophobic or 
hydrophilic substances on hydrophobic printing plates.. 
In U.S. Pat. No. 5,501,150, a fluid ink and hydrophilic media set 
containing materials to produce a silver-reducible image by ink jet 
printing are used to make a metallic silver image which, following wet 
processing to make the silver image sufficiently hydrophobic, is said to 
provide a lithographic printing plate. 
Ink jet printing where the ink is a solid or phase change type ink instead 
of a liquid or fluid type ink is described in U.S. Pat. No. 4,833,486 to 
deposit a hot wax on a surface of an offset plate. Upon cooling of the 
wax, it solidifies, thereby providing a printing plate. Solid ink jet 
printing has serious disadvantages for lithographic plates in that the wax 
or resin image has limited durability due to its thermoplastic, chemical, 
and adhesive properties and the amount and rounded shape of the solidified 
ink jet droplet on the media do not have the intrinsic image resolution 
properties found in liquid or fluid ink jet printing. 
There is also prior art in the use of ink jet printing to apply an opaque 
image or mask pattern to a photosensitive lithographic printing plate 
blank, as for example, in Japanese Kokai 63-109,052. The blank is then 
exposed through the ink jet imaged mask pattern and then processed by 
conventional means to provide a lithographic printing plate. This approach 
retains the materials and processing of conventional lithographic printing 
plates and only uses ink jet printing as an alternative in the photomask 
through which the conventional plates are exposed. Thus this approach adds 
to the complexity and expense of the platemaking process and does not 
depend on the ink jet ink image for the hydrophobic image of the plate. 
U.S. Pat. No. 5,495,803 describes a solid or phase change type of ink jet 
printing to form a photomask for a printing plate. 
Much of the technical development in ink jet printing has been directed to 
color and black imaging for computer hard copy output. The need for more 
archival, durable, and waterfast imaged media has led to ink jet inks and 
receiver media that contain chemically reactive components. For example, 
U.S. Pat. No. 5,429,860 describes a reactive ink jet ink/media set where 
the receiver media has a reactive component which reacts with the ink to 
give a more durable image and reacts in the non-image areas to give a 
durable coating. This patent is directed solely to durable colorant 
imaging elements and has no teaching on durable oleophilic material 
imaging elements or production of lithographic printing plates, which are 
the subjects of the present invention. Other prior art, as for example, 
U.S. Pat. No. 5,006,862 describes the use of reactive colorants in the 
liquid ink jet ink or fluid to provide more durable, waterfast, and bleed 
resistant images when printed on the media. These approaches for archival, 
more durable color and black ink jet images do not address the 
requirements for a durable hydrophobic image suitable for a lithographic 
printing plate. It would be advantageous to have a liquid ink jet ink or 
fluid that could be used on the large installed and future base of ink jet 
printers, now used extensively to print colorants on media, to print a 
durable oleophilic and water-insoluble image, particularly for use on a 
suitable lithographic printing plate blank to make a lithographic printing 
plate. 
Accordingly, it is an object of this invention to provide a liquid ink jet 
ink or fluid that provides an oleophilic, durable, and water-fast image 
upon ink jet printing. 
Another object of this invention is to provide a liquid ink jet fluid-media 
set that provides an olcophilic, durable, and water-fast image with a 
hydrophilic, durable non-image area. It is a further object of this 
invention that this liquid ink jet fluid-media set provides an imaged 
printing plate suitable for high quality lithographic printing. 
It is a further object of this invention that the liquid ink jet 
fluid-media set be capable of being printed on conventional, low cost 
desktop ink jet printers to provide an imaged printing plate suitable for 
high quality lithographic printing. Yet another object of this invention 
is that the liquid ink jet fluid-media set is capable of being printed on 
conventional large format ink jet printers with printing widths and 
lengths in excess of 24 inches to provide an imaged printing plate 
suitable for high quality lithographic printing. Still another object of 
this invention is that the liquid ink jet fluid-media set is capable of 
being printed on ink jet printers of all sizes with a wider choice of 
rigid and flexible media than with laser and other non-impact printers to 
provide an imaged printing plate suitable for high quality lithographic 
printing. 
It is a further object of this invention that no wet processing step, 
before or after the ink jet printing, is required to provide an imaged 
printing plate suitable for high quality lithographic printing. 
It is another object of this invention that no colorant is required in the 
liquid ink jet fluid to provide an oleophilic, durable, and waterfast 
image and to provide an imaged printing plate suitable for high quality 
lithographic printing. 
It is a further object of this invention that no metal precursor is 
required in the liquid ink jet fluid or the media and no metal is required 
in the image areas to provide an oleophilic, durable, and water-fast image 
and to provide an imaged printing plate suitable for high quality 
lithographic printing. 
Still another object of this invention is to provide a convenient and 
economical method to provide an imaged printing plate suitable for high 
quality lithographic printing. 
These and other objects of the present invention will become apparent upon 
a review of the following specification and the claims appended thereto. 
SUMMARY OF THE INVENTION 
In accordance with the foregoing objectives, there is provided by the 
present invention an ink jet liquid or fluid containing an organic or 
transition metal complex reactive component and a hydrophilic media. Such 
a fluid composition and media is, in general, useful as novel materials in 
the preparation of a lithographic printing plate, as well as of durable, 
waterfast imaged materials. In a preferred embodiment, the ink jet fluid 
contains isocyanates, blocked isocyanates, diketenes, diketene emulsions, 
polyamide epoxides, acid anhydrides, acid chlorides, or chromium complexes 
of organic acids as the reactive component. Upon ink jet printing on a 
hydrophilic media and subsequent exposure to an external energy source or 
another suitable means, an oleophilic, durable, and water-insoluble imaged 
media with hydrophilic non-image areas is obtained. 
It is most preferred that the ink jet fluid contains blocked isocyanates, 
diketene emulsions, or chromium complexes of organic acids as the reactive 
component. 
A process for the production of such an imaged lithographic printing plate 
using ink jet printing is also provided herewith. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
The novel ink jet fluid marking material of the present invention comprises 
a liquid carrier and at least one organic or transition metal complex 
reactive component. The liquid carrier is water or organic solvents or 
combinations thereof. Choice of the specific liquid carrier depends on the 
specific ink jet printer and its compatible ink jet printing head and 
cartridge being used for the ink jet printing. It also depends on the 
specific reactive component selected. Compatibility with both the ink jet 
hardware and with the reactive component is important in the selection of 
the liquid carrier. The types of liquid carriers suitable for use with the 
different types of ink jet printheads is known in the art, for example, as 
described in U.S. Pat. No. 5,085,698. In general, the piezoelectric and 
continuous flow types of ink jet printheads have a wider latitude of 
acceptable liquid carriers than the thermal or bubble type of ink jet 
printhead. For example, piezoelectric ink jet printheads work acceptably 
with various non-aqueous or organic liquid carriers while thermal ink jet 
printheads typically need a high percentage of water or volatile organic 
solvent in the liquid carrier. 
Likewise, the reactive components of this invention often have a 
compatibility with the types of liquid carriers that is known in the art. 
For example, some of the reactive components of this invention, such as 
isocyanates, ketenes, and acid anhydrides, are typically sufficiently 
reactive with water that they would only be compatible with non-aqueous or 
organic liquid carriers. If the compatiblity is not known, it can be 
readily estimated by mixing the reactive component in the liquid carrier 
in the desired amounts and using conventional chemical and physical 
methods, such as quantitative analysis of any change or decomposition of 
the reactive component, to measure stability. This is not sufficient to 
insure that the reactive component will be compatible and stable in the 
ink jet printhead during the conditions of storage and printing and in the 
presence of other materials besides the liquid carrier which are typically 
included in the ink jet fluid composition. For this reason, the final 
selection of the suitable liquid carrier for each reactive component needs 
to be demonstrated in the specific ink jet printer to be utilized and with 
the complete ink jet fluid composition, including other additives, 
present. 
The organic and transition metal complex reactive components of this 
invention are selected for their capability, in addition to being 
compatible and stable enough to be utilized in at least one type of ink 
jet printhead with a suitable liquid carrier, to form an oleophilic, 
water-insoluble, and durable image when printed on a hydrophilic receiving 
layer and subsequently exposed to an external energy source or other 
suitable means to cause the reaction of the reactive component. In the 
present invention it is preferred that the reactive component is an 
isocyanate, blocked isocyanate, diketene, diketene emulsion, polyamide 
epoxide, acid arthydride, acid chloride, or chromium complex of an organic 
acid. Examples of these reactive components include isocyanates sold under 
the LUPRANATE trade name by BASF Corporation, such as LUPRANATE M205; 
blocked isocyanates sold under the DESMODUR trade name by Bayer 
Corporation, such as DESMODUR BL3175; diketenes sold under the AQUAPEL 
trade name by Hercules Corporation; diketene emulsions sold under the 
HERCON name by Hercules Corporation, such as HERCON 79; polyamide epoxides 
sold under the POLYCUP trade name by Hercules Corporation, such as POLYCUP 
172; acid anhydrides sold under the GANTREZ Wade name by ISP Corporation, 
such as long alkyl chain vinyl ether-maleic anhydride copolymers; 
palmitoyl chloride from Aldrich Chemical Company; and chromium complexes 
of organic acids sold under the QUILON wade name by Dupont Corporation, 
such as QUILON C, a 25 to 30% by weight solution of the Werner complex of 
trivalent chromium and myristic or stearic acid in isopropyl alcohol, as 
described in Quilon chrome Complexes, Dupont Corporation, April, 1992. In 
a most preferred embodiment, the reactive component is a blocked 
isocyanate, diketene emulsion, or chromium complex of an organic acid. 
While not wishing to be bound to a particular theory, the ink jet inks or 
fluids of the present invention achieve a unique combination of 
oleophilicity, water-insolubility, and durability upon ink jet printing 
and subsequent reaction which is not present in ink jet inks of the prior 
art, including those containing colorants with reactive groups or reactive 
additives and those containing titanate and silane coupling agents. This 
advantageous combination of properties is attributed in part to the 
superior film forming properties of the reactive components of the present 
invention. These film forming properties provide the good mechanical 
integrity or durability over a range of image thicknesses and the strong 
bonding to the receiving layer that are needed for demanding applications 
such as lithographic printing plates and for other archival, durable 
applications in general. 
Another preferred reactive component is an electron beam, ultraviolet, 
visible, or infrared radiation curable material. In a most preferred 
embodiment, the radiation curable material contains unsaturated acrylic or 
vinyl groups. With the proper selection of radiation-sensitive reactive 
groups and of olcophilic groups in these radiation curable materials, the 
unique combination of oleophilicity, durability, and water-insolubility 
properties described above can also be achieved with these film forming 
materials. 
The media of the present invention is for use with the ink jet fluid 
marking material of the present invention and comprises a support that 
beaus a receiving layer containing at least one hydrophilic material. The 
selection of this hydrophilic material is made based on its performance in 
three main areas: receptivity to the ink jet fluid marking material to 
provide a high quality image with the desired resolution, amount, and 
uniformity; interaction with the reactive component in the ink jet fluid 
to provide a durable image; and the hydrophilic properties and 
water-fastness properties needed for high quality lithographic printing. 
For example, most aqueous-based ink jet fluids need a hydrophilic 
receiving surface for good image quality. The hydrophilic properties and 
water-fastness needed in lithographic printing are well known in the art. 
Preferred hydrophilic materials in the present invention are polyvinyl 
alcohols and copolymers thereof, cellulosic polymers, polyvinyl acetates 
and copolymers thereof, polyacrylates and copolymers thereof, 
polymethacrylates and copolymers thereof, polymaleic anhydrides and 
derivatives and copolymers thereof, polyvinyl acetals and copolymers 
thereof, polyvinyl pyrrolidones and copolymers thereof, polyamides, or 
inorganic polymers. In a most preferred embodiment, the hydrophilic 
material contains polyvinyl alcohol or a copolymer thereof, aluminum 
boehmite, alumina, a silicate, or silica. The inorganic polymers are 
typically formed from a sol gel, colloidal particle deposition, or 
anodization process to provide a gel or network of inorganic polymer. 
Although the supports for the media of this invention can be selected from 
a wide range of materials commonly used in lithographic printing plates 
with a basic requirement that the media with this support be capable of 
transport through the ink jet printing hardware where the media is 
required to be transported, the preferred supports are paper, plastic 
polymer film, or aluminum. 
After the ink jet fluid marking material of the present invention is 
printed on the media of this invention, the reactive component needs to be 
reacted by exposure to an external energy source or other suitable means. 
For the non-radiation curable reactive components of the present 
invention, the preferred external energy source is heat. For the radiation 
curable reactive components of the present invention, the preferred 
external energy source is the radiation, such as ultraviolet radiation, to 
which the material is most efficiently sensitive. For some non-radiation 
curable reactive components such as some isocyanates, ambient conditions 
are sufficient means to provide an effective reaction. 
In a preferred embodiment, a catalyst is added to the ink jet fluid marking 
material to increase the rate of reaction of the reactive component after 
printing and upon exposure to the external energy source or other suitable 
means to cause reaction. In a most preferred embodiment, the catalyst that 
is added is a metal complex, such as stannous stearate. 
In another preferred embodiment, the receiving layer of the media also 
comprises a catalyst to increase the rate of reaction of the reactive 
component after printing and upon exposure to the external energy source 
or other suitable means to cause reaction. In a most preferred embodiment, 
the catalyst that is added to the receiving layer is an alkaline material. 
Some of the reactive components react under alkaline conditions, but are 
stable in acidic conditions. Thus, these reactive components must be in 
the ink jet fluid of the present invention in an acidic environment, but 
require the presence of an alkaline material in the receiving layer to 
cause the desired reactivity. 
In another embodiment of the present invention, the reactive component in 
the ink jet fluid marking material reacts with the hydrophilic material in 
the receiving layer of the media. In a preferred embodiment, the reactive 
component that reacts with the hydrophilic material in the receiving layer 
is an isocyanate, blocked isocyanate, diketene, diketene emulsion, 
polyamide epoxide, acid anhydride, acid chloride, or chromium complex of 
an organic acid. In a most preferred embodiment, the reactive component 
that reacts with the hydrophilic material in the receiving layer is a 
blocked isocyanate, diketene emulsion, or chromium complex of an organic 
acid. 
The novel method of preparing an imaged lithographic printing plate of the 
present invention comprises providing a lithographic plate blank having a 
support that bears a receiving layer containing at least one hydrophilic 
material. An image is formed on this receiving layer using an ink jet 
printer which prints an ink jet fluid marking material which comprises a 
liquid carrier medium and at least one organic or transition metal complex 
reactive component. After ink jet printing, the lithographic plate blank 
with the imaged pattern comprising the reactive component is exposed to an 
external energy source or other suitable means to cause the reaction of 
the reactive component. This forms an effective amount of an oleophilic 
and water-insoluble pattern on the lithographic plate blank, thereby 
preparing it for high quality lithographic printing. 
In a preferred embodiment of the method of the present invention, the 
reactive component is an isocyanate, blocked isocyanate, diketene, 
diketene emulsion, polyamide epoxide, acid anhydride, acid chloride, or 
chromium complex of an organic acid. In a most preferred embodiment of the 
method of the present invention, the reactive component is a blocked 
isocyanate, diketene emulsion, or chromium complex of an organic acid. 
The invention will now be more fully explained by the following examples. 
However, the scope of the invention is not intended to be limited to these 
examples.

EXAMPLE 1 
An EPSON (trade name of Epson Corporation) black ink jet cartridge, catalog 
#5020047, was opened. After removing the internal sponge, the cartridge 
was rinsed thoroughly with dimethyl sulfoxide. An ink jet fluid consisting 
of 1 part of a blocked isocyanate, sold under the trade name of DESMODUR 
BL3175A by Bayer Corporation, and 4 parts of dimethyl sulfoxide was 
prepared and used to fill the cartridge. The cartridge was then taped shut 
and placed in the cartridge holder of an EPSON ink jet printer, a 
piezoelectric type desktop ink jet printer sold under the trade name of 
STYLUS COLOR IIS. 
Images were jetted on to printing plates sold under the trade name of the 
GENIE brand. The images were heated for 5 minutes with a hot air gun set 
at 900.degree. F. and held at 18 inches from the imaged plate. 
The ink receptivity in the imaged areas only was found to be excellent by 
soaking the sheet under tap water for 30 seconds and then rubbing a 
standard black rubber-based offset ink on the imaged surface side followed 
by a water wash. 
EXAMPLE 2 
A HEWLETT KARD (trade name of Hewlett Packard corporation) black ink jet 
cartridge, catalog #51625A, was emptied by piercing the top plug and 
withdrawing the liquid ink with a pipette. The cartridge was then rinsed 
twice with a solution consisting of 3 parts of isopropyl alcohol and 2 
parts of dimethylsulfoxide. An ink jet fluid consisting of 4 parts era 
chromium complex of an organic acid, sold as a 25 to 30% solution in 
isopropyl alcohol under the trade name of QUILON C by Dupont Corporation, 
and 1 part of isopropyl alcohol was prepared and used to fill the 
cartridge with the aid of a pipette. The cartridge was then placed in the 
cartridge holder of a HEWLETT KARD ink jet printer, a thermal type 
desktop ink jet printer sold under the trade name of HP540C, and imaged, 
treated with heat, and tested as described in Example 1. The ink 
receptivity in the imaged areas only was found to be excellent and similar 
to the results in Example 1. 
EXAMPLE 3 
The cartridge containing QUILON C from Example 2 was placed in the 
cartridge holder of an ENCAD (trade name of Encad Corporation) ink jet 
printer, a thermal type 36 inch wide ink jet printer sold under the trade 
name of NOVAJET III. Imaging, heat treatment, and testing as described in 
Example 1 gave results similar to the results in Example 1. 
EXAMPLE 4 
The procedure of Example 2 was followed except that a diketene emulsion, 
sold as a 10% solids emulsion by Hercules Corporation under the trade name 
of HERCON 79, was substituted for the ink jet fluid containing the QUILON 
C. The ink receptivity was found to be in the imaged areas only and 
similar to the results in Example 2. 
EXAMPLE 5 
The procedure of Example 1 was followed except that the imaging was done on 
a coated white opaque polyester film, sold by Epson Corporation under the 
trade name of EPSON GLOSSY PAPER. Analysis of the hydrophilic coating on 
the polyester film showed it to contain both aluminum boehmite inorganic 
polymer and a polyvinyl alcohol. The ink receptivity in the imaged areas 
only was found to be excellent and similar to the results in Example 1. 
EXAMPLE 6 
The imaged and heat treated plates from Examples 1 and 2 were primed on a 
conventional lithographic wet offset press using an oil-based black ink 
from Van Son Corporation and a fountain solution diluted by a ratio of 
1:10 from a concentrate sold by Itek Corporation under the trade name of 
MEGAPLATE FOUNTAIN CONCENTRATE. Satisfactory image quality was achieved on 
the printed paper sheets throughout a continuous run of 3,000 impressions 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the an 
that various changes and modifications can be made without departing from 
the spirit and scope thereof.