Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
1997-06-06
2001-03-06
Schwartz, Pamela R. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C428S195100, C428S914000, C156S235000
Reexamination Certificate
active
06197409
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to media used in ink-jet printing, and more particularly to media that provide a durable, water-fast image.
BACKGROUND OF THE INVENTION
Ink-jet printing is a non-impact method for recording information in response to an electronic signal, such as that generated by a computer. In the printer, the electronic signal produces droplets of ink that are deposited on media, such as paper or transparent film. Ink-jet printers have found broad commercial acceptance due to their reliability, relatively quiet operation, graphic capability, print quality, and low cost.
In current ink-jet printing applications, several inks (typically black, cyan, magenta and yellow) are used to print textual and graphic information on a printing medium, typically ordinary paper. The inks primarily are composed of water, and contain a colorant that may be a dye or pigment dispersion. Pigment dispersions are preferred since the dyes are highly soluble and tend to smear upon handling. Pigment dispersions offer improved water and smear resistance, as well as better light stability. The inks generally also contain a polyhydric alcohol to prevent nozzle clogging, and may contain various adjuvants. Such inks and ordinary paper are well suited for desk-top publishing, as currently practiced, wherein only a small portion of the paper receives printed text and graphic information.
It also is desired to reproduce high quality colored pictoral information (such as photographs and the like) using ink-jet technologies for applications such as commercial printing and desk-top publishing. In these applications, however, the printing medium will receive substantially more of the black and colored inks in order to accurately reproduce the various hues, tints, and colors contained in a typical colored picture. For example, the printing medium will be expected to receive up to 200% or more coverage in conventional commercial printing applications.
Ordinary paperstock is not suitable for such high quality applications for a number of reasons. Water disrupts the paper structure, causing “cockle” that affects appearance of the paper and, in extreme cases, may actually cause the paper to distort to the extent that it contacts the ink-jet pen, disrupting the printing process. Also, the paper may not absorb water sufficiently quickly to achieve the desired printing speed, or may cause flooding of the paper surface, which adversely affects image quality. Moreover, wicking of ink into the paper may cause the paper to “show through” into the printed image, detracting from image quality. There also is a need for the printed text and pictures to be more robust; e.g., exhibit better handleability, water fastness, and smear resistance after printing.
Special ink-jet media currently employ vehicle absorbtive components, and optionally additives, to bind the dyes to the media. The purpose is to provide reduced bleed, whereby the intrusion of one color into an adjacent color is minimized. As a consequence current media are inherently moisture sensitive, can be quite fragile to handling, and are subject to finger smearing. Moreover, the vehicle absorptive components usually consist of water-soluble polymers which results in slower printing speeds. In addition the water absorptive components leave the paper quite sensitive to moisture and smearing.
Thus, a need exists for media that will provide a printed image having improved durability, water-fastness, and smear resistance in both imaged and non-imaged areas. A specific need exists for such media capable of reproducing colored pictoral information in high quality, thereby meeting the demanding requirements of commercial printing.
SUMMARY OF THE INVENTION
The present invention provides a media particularly adapted to receive printed images involving large quantities of an aqueous ink-jet ink containing a pigment colorant. The printed image is readily transferred to a permanent substrate, which may be paper, due to an adhesive component contained in the ink-receiving layer of the media.
Accordingly, in one embodiment, the invention provides a media particularly adapted to receive a pigmented ink image from an ink-jet printer for subsequent transfer to a permanent substrate. The media has, in order:
(a) a substrate;
(b) a water-absorbing layer comprising a hydrophilic polymer that is substantially solid in the presence of aqueous pigmented ink; and
(c) a transparent, adhesive, ink-receiving layer that retains the aqueous ink pigment and is permeable to the aqueous ink medium.
In preferred embodiments, the ink-receiving layer may contain a thermoplastic polymer that is subsequently cross-linked, conveniently by lamination, as the ink-receiving layer is transferred to a permanent substrate. This cross-linking improves durability of the printed image. The ink-receiving layer also may contain a Reactive Component that aids binding of the ink colorant to the ink-receiving layer.
In other embodiments, the invention provides a process for using the media to create a printed image on the media, and transfer the printed image to a permanent substrate. The media and process provide special utility in demanding ink-jet printing applications involving printing of pictoral information, which requires more ink than normally used in printing text.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides an ink-jet transfer media that provides printed images having improved durability, water-fastness and smear resistance, on both imaged and non-imaged areas of the media.
The media is adapted to receive the relatively large volumes of ink needed to generate high quality pictoral information, and has a substrate, a water-absorbing layer, and an ink-receiving layer.
MEDIA SUBSTRATE
The media substrate (i.e., “support”) is a material having sufficient stiffness and dimensional stability to support a printed image without having the image distort or misalign, and sufficient water resistance that it can be exposed to an aqueous ink without warping or shrinkage. The material also must withstand heat and pressure applied during the lamination steps described below. The support typically has a thickness of about 25 to about 250 micrometers (1.0 to 10 mils), preferably about 50 to 200 micrometers (2 to 8 mils). Suitable materials include polymeric films, such as polyethylene terephthalate and polyethylene naphthanate, polyamides, polycarbonates, fluoropolymers, polyacetals, and polyolefins. Thin metal sheets may be selected, as well as natural or synthetic paper treated to be water resistant. The substrate may be transparent, translucent, or opaque. It may be colored and can have components, such as antihalation dyes, incorporated therein to meet the needs of specific applications. Polyethylene terephthalate films are a preferred support material.
Conventional antistat coatings may be present on one or both sides of the support to reduce static if the support is later separated from its coating layer by “peeling”, as discussed below. The substrate also may have a release layer or surface if it is desired to peel the substrate off after transfer. Materials having a release surface, such as polyethylene or a fluoropolymer, may be selected. Alternatively, a thin release layer may be used to promote separation of the media layers. Useful release layers are well known in the art and include, for example, silicones, melamine acrylic resins, vinyl chloride polymers and copolymers, vinyl acetate polymers and copolymers, plasticized polyvinyl alcohols, ethylene and propylene polymers and copolymers, etc. When a separate release layer is coated onto the support, the layer generally has a thickness in the range of 0.5 to 10 micrometers. The release layer may also contain materials such as antistats, colorants, antihalation dyes, optical brighteners, surfactants, plasticizers, coating aids, matting agents, and the like.
An anchor layer may be used to ensure adequate adhesion of the release layer (if used) to the support. The term “anchor layer”, as employed in the art, mean
Bodager Gregory A.
Fickes Daphne Pinto
Held Robert Paul
Moehlmann Jon Gregory
Work, III Ray Alexander
E. I. Du Pont de Nemours and Company
Schwartz Pamela R.
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