Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making printing plates
Reexamination Certificate
2002-07-31
2004-07-06
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making printing plates
C430S271100, C430S905000, C430S910000
Reexamination Certificate
active
06759178
ABSTRACT:
This invention relates to a polymeric film, and in particular to a polymeric film which is substantially gelatin free and has a coating layer which is suitable for use as a component of a printing plate.
Printing plates, particularly lithographic printing plates, generally comprise a substrate, a hydrophilic coating layer, and a photopolymerizable light-sensitive layer. Imagewise exposure, by a suitable light source, results in hardening of the photopolymerizable layer, allowing the unhardened portions of the layer to be removed by washing with a solvent. The result is a hydrophobic polymer image on a hydrophilic substrate, which can be used as a lithographic printing plate. In an alternative process, a hydrophobic toner is applied to the hydrophilic coating layer by means of a laser imaging process.
The surface properties of the hydrophilic coating layer can be crucial in determining the quality of the final printed image. For example, some prior art hydrophilic coating layers exhibit poor coat quality and insufficient adhesion to the underlying substrate and/or overlying photopolymerized layer or toner. In addition, the coating layer may possess insufficient hydrophilicity and/or a surface topography which can lead to inadequate removal of the unhardened photopolymerized portions, resuming in the formation of a relatively poor quality printed image. In laser toner based processes the hydrophilic coating layer may require antistatic properties to control or avoid toner scatter, which reduces the quality of the final image.
Relatively high temperatures are employed in some processes used for producing printing plates, which can affect the curl and flatness of any polymeric film present in a printing plate.
Hydrophilic coating layers such as gelatin are traditionally applied to a polymeric film after the production of the film has been completed, i.e., “off-line”, which results in an increase in the number of process steps required to produce the coated film. There is a need to be able to apply the coating layer during the film making process, i.e., “in-line”, without the use of gelatin in order to simplify and improve the efficiency of the production process.
We have now devised a polymeric film which reduces or substantially overcomes at least one of the aforementioned problems.
Accordingly, the present invention provides a polymeric film which is substantially gelatin free and comprises a polymeric film substrate having on at least one surface thereof, a coating layer comprising a polymer comprising at least one or more repeating units comprising at least one or more pendant (—POXY) groups, wherein X and Y, which may be the same or different, are OH or OM wherein M is a cation.
The invention further provides a method of producing a polymeric film which comprises forming a polymeric film substrate, applying a coating composition to at least one surface of the substrate, the coating composition comprising a polymer comprising at least one or more repeating units comprising at least one or more pendant (—POXY) groups, wherein X and Y, which may be the same or different, are OH or OM wherein M is a cation.
The invention also provides a printing plate comprising a polymeric film substrate having on at least one surface thereof, a coating layer comprising a polymer comprising at least one or more repeating units comprising at least one or more pendant (—POXY) groups, wherein X and Y, which may be the same or different, are OH or OM wherein M is a cation.
The polymeric film according to the invention can also be fused as coating for mirrors, in particular car mirrors, and building surface cladding. The polymeric film substrate is a film capable of independent existence in the absence of a supporting base.
The substrate, to which a coating layer composition is applied to yield a polymeric film according to the invention, may be formed from any suitable film-forming, polymeric material. Thermoplastics materials are preferred, and include a homopolymer or copolymer of a 1-olefin, such as ethylene, propylene and but-1-ene, a polyamide, a polycarbonate, more preferably a polyester, and particularly a synthetic linear polyester which may be obtained by condensing one or more dicarboxylic acids or their lower alkyl (up to 6 carbon atoms) diesters, e.g., terephthalic acid, isophthalic acid, phthalic acid, 2,5-, 2,6- or 2,7-naphthalenedicarboxylic acid, succinic acid, sebacic acid, adipic acid, azelaic acid, 4,4′-diphenyldicarboxylic acid, hexahydro-terephthalic acid or 1,2-bis-p-carboxyphenoxyethane (optionally with a monocarboxylic acid, such as pivalic acid) with one or more glycols, particularly aliphatic glycols, e.g., ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol and 1,4-cyclohexane-dimethanol. A polyethylene terephthalate and/or polyethylene naphthalate film is preferred. A polyethylene terephthalate film is particularly preferred, especially such a film which has been biaxially oriented by sequential stretching in two mutually perpendicular directions, typically at a temperature in the range from 70 to 125° C., and preferably heat set, typically at a temperature in the range from 150 to 250° C., for example as described in GB-A-838708. Another preferred film comprises a copolymer of terephthalic and isophthalic acids with ethylene glycol. The substrate may also comprise a polyarylether or thio analogue thereof, particularly a polyaryletherketone, polyarylethersulphone, polyaryletherether-ketone, polyaryletherethersulphone, or a copolymer or thioanalogue thereof. Examples of these polymers are disclosed in EP-A-1879, EP-A-184458 and U.S. Pat. No. 4,008,203. Blends of these polymers may also be employed. A poly p-phenylene sulphide film is also suitable.
Suitable thermoset resin substrate materials include addition-polymerization resins, such as acrylics, vinyls, bis-maleimides and unsaturated polyesters, formaldehyde condensate resins such as condensates with urea, melamine or phenols, cyanate resins, isocyanate resins, epoxy resins, functionalized polyesters, polyamides or polyimides.
A film substrate for a polymeric film according to the invention may be unoriented or preferably oriented, for example uniaxially oriented, or more preferably biaxially oriented by drawing in two mutually perpendicular directions in the plane of the film to achieve a satisfactory combination of mechanical and physical properties. Formation of the film may be effected by any process known in the art for producing a polymeric film, for example a tubular or a flat film process.
In a tubular process simultaneous biaxial orientation may be effected by extruding a thermoplastics polymeric tube which is subsequently quenched, reheated and then expanded by internal gas pressure to induce transverse orientation, and withdrawn at a rate which will induce longitudinal orientation.
In the preferred flat film process a film-forming polymer is extruded through a slot die and rapidly quenched upon a chilled casting surface (drum) to ensure that the polymer is quenched to the amorphous state. Orientation is then effected by stretching the quenched extrudate in at least one direction at a temperature above the glass transition temperature of the polymer. Sequential orientation may be effected by stretching a flat, quenched extrudate firstly in one direction, usually the longitudinal direction, i.e. the forward direction through the film stretching machine, and then in the transverse direction. Forward stretching of the extrudate is conventionally effected over a set of rotating rolls or between two pairs of nip rolls, transverse stretching then being effected in a stenter apparatus. Stretching is effected to an extent determined by the nature of the film-forming polymer, for example a polyester is usually stretched so that the dimension of the oriented polyester film is from 2.5 to 4.5 its original dimension in the, or each, direction of stretching.
A stretched film may be, and preferably is, dimensionally stabilized by heat-setting under dimensional restraint at a temperature above the glas
Brabbs Noel Stephen
Chappel, Jr. Cornell
Goodchild Karen
Rogers Stephen Derek
Siddiqui Junaid Ahmed
Dupont Teijin Films US Limited Partnership
Huff Mark F.
Lee Sin J.
LandOfFree
Polymeric film having a coating layer of a phosphonic acid... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polymeric film having a coating layer of a phosphonic acid..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polymeric film having a coating layer of a phosphonic acid... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3217480