Stock material or miscellaneous articles – Ink jet stock for printing – Plural ink receptive layers
Reexamination Certificate
2000-11-09
2003-07-15
Hess, B. Hamilton (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Plural ink receptive layers
C428S032270, C428S032280
Reexamination Certificate
active
06592953
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an ink receiving sheet for ink-jet printing and, more particularly, to a receiving sheet comprising a copolymer consisting in at least one N-vinylpyrrolidone monomer and at least one second monomer selected from the group of N-vinylcaprolactam, and N-vinylpiperidone monomers to improve post printed drop sweating in the resulting image, still maintaining a good glossiness.
BACKGROUND OF THE INVENTION
Ink jet printing has become increasingly popular, particularly for so-called “desk-top publishing”, because of its capability to produce small volumes of printed matter from digital input at high throughput speeds. Recent equipment developments have led to the introduction of multi-color ink jet printers that integrate colored graphics and text. To some extent, however, the applications of ink jet printing have been limited due to the demanding requirements the ink receptors must meet in order to provide high quality text and graphics.
It is desirable that receiving media for inkjet printing are capable of absorbing significant amount of liquid to ensure that the surface of said receptors be dry and non tacky to the touch after printing; but it is also desirable to maintain durability of printing image.
In case of multicolor ink-jet receptors, the ink-receiving layer is often subjected to multiple print, one for each primary color (yellow, magenta and cyan). During the first or second print, the amount of organic compounds absorbed in the layer can be partially desorbed creating on the image surface a local organic compound concentration that are visible as drop. Where a yellow ink is absorbed by the ink receiving layer after that cyan and magenta inks have been already absorbed therein, it is possible to have the formation of yellow colored drops in specific areas on the surface of the receiving layer, areas that have been saturated with cyan and magenta inks and that are no more able to properly absorb additional inks. This problem is generally known as post printed drop sweating.
U.S. Pat. No. 4,649,064 discloses a rapid-drying image-recording element adapted for water-based liquid ink marking, in devices such as pen plotters, ink jet printers and the like, comprising a support having thereon a hydrophilic ink-receiving layer which is cross-linked to a degree sufficient to render it non-blocking and waterfast while permitting it to rapidly absorb a water-based liquid ink. The element is utilised in combination with a water-based liquid ink that comprises a water-dispersible cross-linkable colorant/resin composition and the ink-receiving layer contains a cross-linking agent which cross-links the colorant/resin composition to thereby render the ink markings smear-resistant, abrasion-resistant and waterfast.
U.S. Pat. No. 5,919,558 discloses typical water soluble and non-water soluble polymeric binders for inkjet coatings, such as, for example, poly(vinylpyrrolidone), vinylpyrrolidone-vinyl acetate copolymers, or mixtures thereof. U.S. Pat. No. 4,425,405 discloses such a mixture applied on at least one surface of a paper substrate or incorporated internally of the substrate with a white filler in a pigment-to-binder weight ratio of 10:1 to 0.2:1. In addition, U.S. Pat. No. 4,503,111 discloses the use of poly(vinylpyrrolidone) as the binder in an inkjet recording sheet which uses a hydrophobic substrate prepared from a flexible, transparent plastic material.
U.S. Pat. No. 5,939,469 discloses a base material and a coating on said base material for binding anionic dyes of ink-jet inks to the base; said coating comprises (a) 50 to 99.5% by weight of a basic vinyl heterocycle selected from the group consisting of N-vinylimidazole, 2-methyl-1-vinylimidazole and a mixture thereof; said vinyl heterocycle having a pKa of at least 3.8; (b) 0 to 49.5% by weight of a further copolymerizable monomer; and (c) 0.5 to 10% by weight of a crosslinker. In particular, the further copolymerizable comonomer (b) is selected from the group consisting of N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyl-1,4-dihydropyridine and a mixture thereof.
U.S. Pat. No. 4,904,519 describes an ink jet recording sheet comprising a transparent polymeric backing having on at least one major surface thereof a transparent, ink-receptive layer comprising a cross-linked, hydrolyzed copolymer of a vinyl ester comonomer selected from the group consisting of vinyl acetate, vinyl propionate and vinyl stearate, and a vinyl amide comonomer selected from the group consisting of N-vinyl pyrrolidone and vinyl acetamide, the degree of hydrolysis being from about 80 to 95%, and the cross-linking being effected by an agent selected from the group consisting of borates, titanates, dichromates and aldehydes.
When the ink receptor media is printed with high quantity of ink, water and other components are absorbed by the coated layer and retained inside the film. At high humidity conditions, they tend to come off the layer and to coalesce in form of small drops on the surface, causing an oily feeling to touch and several handling problems. EP Patent Application 763,433 claims an ink jet recording medium containing at least one nitrogen-containing component to be selected from poly(vinylpyrrolidone), polyimines, gelatines or quaternary polymers. It should be assumed that one or more of these nitrogen-containing entities can function at least partially as a mordant.
A wide variety of the vinyl pyrrolidone polymers and copolymers of vinyl pyrrolidone with copolymerizable monomers such as vinyl acetate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, methyl acrylamide, methyl methacrylamide and vinyl chloride are commercially available and/or are disclosed in U.S. Pat. Nos. 4,741,969; 4,503,111; 4,555,437 and 4,578,285 and PCT application 92-09,440. The concentration of the vinyl pyrrolidone polymer in the ink-receptive layer is subject to some variation. It is used in sufficient concentration to absorb or mordant the printing ink in the layer. A useful concentration is generally in the range of about 15 to about 50 percent by weight based on the total dry weight of the layer, although concentrations somewhat in excess of about 50 weight percent and concentrations somewhat below about 15 weight percent may be used in the practice of the invention.
JP Patent Application 63-307,979 discloses a coating for ink-jet printing containing a hydrophilic soluble copolymer of vinylimidazole, vinylpyrrolidone and vinylbenzylsulfonic acid (60:30:10).
Despite polyvinylpyrrolidone derivatives work as good mordants with the majority of dyes used in ink formulations, they have low ability to fix other components (such as alkylene glycoles, low molecular weight polyoxyethylene compounds) that cause the bleeding phenomen. Hence, there is still a need for improved ink receptors that have minimum post printed drop sweating, still maintaining a good glossiness.
SUMMARY OF THE INVENTION
The present invention refers to an ink jet receiving sheet which comprises a support and at least one ink receiving layer comprising a binder selected from the group consisting of gelatin and gelatin derivatives, characterized in that said at least one ink receiving layer comprises at least a copolymer consisting of at least one N-vinylpyrrolidone monomer and at least one second monomer selected from the group of N-vinylcaprolactam monomer and N-vinylpiperidone monomer, to improve post printed drop sweating in the resulting image, still maintaining a good glossiness.
DETAILED DESCRIPTION OF THE INVENTION
The ink jet receiving sheet of the invention comprises a support and at least one ink receiving layer comprising a binder selected from the group consisting of gelatin and gelatin derivatives. Any gelatin made from animal collagen can be used, but gelatin made from pig skin, cow skin or cow bone collagen is preferable. The kind of gelatin is not specifically limited, but lime-processed gelatin, acid processed gelatin, amino group inactivating gelatin (such as acetylated gelatin
Ceruti Luca
Impellizzieri Gabriele
Sardelli Roberto
Ferrania S.p.A.
Hess B. Hamilton
Mark A. Litman & Assoc. P.A.
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