Coating compositions for forming inkjet-receptive coatings on a substrate

This application corresponds to U.S. Provisional Patent Application Ser. No. 60/730,132, filed Oct. 25, 2005 and Ser. No. 60/735,545, filed Nov. 10, 2005, the complete disclosures of each of these applications is hereby incorporated by reference herein.

1. Field of the Invention

This invention relates to inkjet printing onto a coated substrate, and, more particularly, to coating compositions which enable the ink to be absorbed onto the substrate effectively.

2. Description of the Prior Art

lnkjet printing is a highly successful method of forming images on different substrates such as paper, polyester, vinyl and canvas. However, it is desired to provide new and improved inkjet coating compositions which exhibit advantageous properties in commercial use. One such sought-after property, is an ability to absorb and retain the ink effectively.

What is described herein is an inkjet coating composition of the invention which includes:

(a) poly(diallyldimethyl ammonium chloride) (pDADMAC), (b) a crosslinkable cationic copolymer, (c) colloidal silica, (d) silica gel, (e) a binder, preferably vinyl acetate-ethylene copolymer, and (f) water.

A suitable coating composition for forming an inkjet-receptive coating on a substrate comprises:

(a) p(diallyidimethyl ammonium chloride),

(b) a crosslinkable cationic polymer,

(c) colloidal silica,

(d) silica gel,

(e) a binder, and

(f) water.

Preferably, the coating composition comprises, by weight,

(a) is 0.1-30%,

(b) is 1-50%,

(c) is 0.1-50%,

(d) is 0.1-55%,

(e) is 0.1-45%, and

(f) to 100%.

Most preferably, the coating composition comprises, by weight,

(a) is 1-25%,

(b) is 5-45%,

(c) is 1-20%,

(d) is 5-50%,

(e) is 5-35%, and

(f) to 100%.

Optimally, the coating composition comprises, by weight,

(a) is 2-20%,

(b) is 10-35%,

(c) is 2-10%,

(d) is 10-45%,

(e) is 6-25%, and

(f) to 100%.

Preferably (b) is a terpolymer of quaternized vinyl caprolactam (VCL), dimethylaminopropyl methacrylamide (DMAPMA) and hydroxyl ethyl methacrylate (HEMA), e.g. by weight, the terpolymer comprises 60-90% VCL, 10-30% DMAPMA and 2-10% HEMA.

Alternatively, (b) is a copolymer of vinyl pyrrolidone (VP) and dimethylaminopropyl methacrylamide (DMAPMA).

Suitably, the coating composition of the invention may include one or more of the following optional ingredients: crosslinked PVP; PVP, polyvinyl alcohol, a copolymer of vinyl pyrrolidone and dimethylaminopropyl methacrylamide neutralized with HCl or sulfuric acid, a crosslinker, calcium carbonate, titanium dioxide, barium sulfate, barium chloride, aluminum sulfate, aluminum chloride, polyethyloxazoline, Disintex® 1000, and/or a surfactant.

Suitably the coating composition of the invention forms a matte-finished inkjet coating on polyester, vinyl, paper and canvas.

Generally, the coating composition has a solids content of about 15-30%, and a viscosity of about 200-400 cps.

Preferably, (e) is a vinyl acetate-ethylene copolymer; (c) has a particle size of about 20-150 nm, and (d) has a particle size of about 1.5 to 10μ, most preferably, (c) has a particle size of about 25-50 nm, and (d) has a particle size of about 4.5 to 8μ.

Suitably, in the coating composition (e) is a latex.

What is formed herein is an inkjet-receptive coated substrate coated with the dried composition of the invention, which forms color inkjet images which dry rapidly, has good color density, exhibits low color density loss, and is water-resistant and adhesive.

Another embodiment of the invention is an aqueous dispersion of the inkjet composition.

In the composition of the present invention, the crosslinkable cationic polymer (b) suitably can comprise tertiary amino groups and/or hydroxyl groups. Preferably, (a) is a crosslinkable polymer of a vinyl lactam/dimethylaminopropyl methacrylamide/hydroxyethyl methacrylate terpolymer or a vinyl lactam/dimethylaminopropyl methacrylamide copolymer. A preferred vinyl lactam is vinyl caprolactam. A particularly preferred example of such a cationic polymer is the resin ViviPrint™ 200 manufactured by International Specialty Products (ISP). Such terpolymer preferably comprises vinyl caprolactam (VCL), dimethylaminopropyl methacrylamide (DMAPMA) and hydroxyethyl methacrylate (HEMA), uncrosslinked or crosslinked, unquatemized or quaternized, preferably quaternized and crosslinked. Suitable quaternizing agents include HCl and H 2 SO 4 . Preferably, the terpolymer comprises, by wt., 60-90% VCL, 10-30% DMAPMA and 2-10% HEMA, preferably 75-80% VCL, 13-16% DMAPMA and 4-6% HEMA.

Another preferred example of a cationic copolymer is the resin ViviPrint™ 131, 121 or 300, manufactured by ISP. For example, ViviPrint 131 is VP/DMAPMA copolymer neutralized with HCl.

The terpolymer suitably has a molecular weight of about 500,000 to about 1,500,000, preferably about 500,000 to about 1,000,000.

The cationic polymer suitably can be present in an amount by weight, of about 1 to about 50%, and, preferably, for ViviPrint™ 200, about 5 to about 45%, and, more preferably, of about 10 to about 40%, of the composition.

The colloidal silica (c) suitably are amorphous colloidal silica particles e.g. 20-150 nm. Preferred colloidal silicas are Silcron IJ-25 and IJ-50.

The silica gel (d) suitably are amorphous colloidal silica particles, e.g. 1.5-10μ. A preferred silica gel is Silcron G100.

In a preferred embodiment of the invention, the binder (e) is a vinyl acetate-ethylene copolymer e.g. Airflex® 465 Emulsion, available from Air Products. Airflex® 465 emulsion is a rapid-setting vinyl acetate-ethylene copolymer, which is a high-solids emulsion. This polymer adheres well to various substrates such as polyester, poly(ethylene terephthalate), tempered aluminum foil and polystyrene. This emulsion combines a high-solids content with a low viscosity, which is a combination that permits the addition of high-filler loadings, resulting in adhesive formulations with solid contents of 80%, or more. Furthermore, this emulsion does not thicken excessively on the addition of plasticizers which allows for the formulation of very high-solids adhesives. Airflex® 465 emulsion also is shear stable, and can be applied on high-speed packaging machines using roll, extrusion or spray equipment. The emulsion dries to a slightly tacky, clear, water-resistant film.

Optional components in:the composition for optimization of the coating composition when coated on different substrates include pigments, clays, e.g. organoclays and water-swellable clays, acrylic polymers, acrylic copolymers, alginates, carrageenan, microcrystalline cellulose, gelatin, carboxymethylcellulose sodium, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, methylcellulose, guar and guar derivatives, locust bean gum, polyethylene oxide, polyvinylpyrrolidones, copolymers of polyvinylpyrrolidones, polyvinylalcohols, other water soluble polymers, silica, aluminates, zirconates, calcium carbonates, xanthan gum and the like, polymers or copolymers of a water soluble vinyl lactam optionally having in situ-formed particles of crosslinked vinyl lactam polymer or copolymer, crosslinked polyvinyl pyrrolidone, and crosslinkers to achieve advantageous inkjet printable surface coatings having light stability. Preferred components and optimal amounts of these components will depend upon the specific support coating and application and can be readily determined by one of ordinary skill in the art.

The inkjet coating compositions of the invention can provide a matte finish coating on polyester, vinyl, paper or canvas.

Step 2: Add 65 g of Silcron G-100 (ISP/Millenium), 13 g of BaSO 4 , 13 g of ViviPrint PS10 (ISP) and 2 g of TiPure TiO 2 (duPont). Homogenize.

Step 3: Add 130 g of Airflex 465 (Air Products). Mix thoroughly, homogenize if necessary.

Step 4: Add 390 g of Aquazol 200 (ISP/PCI, 20% solids in water, previously made). Mix thoroughly, homogenize if necessary.

Step 5: Add 197 g of ViviPrint 200 (ISP, “as is”). Mix thoroughly, homogenize if necessary.

Step 3: Add 1 g of pDADMAC, 0.75 g UCAR 313 (Dow), 2.65 g of ViviPrint 200 (ISP). Mix thoroughly. This is vessel 2.

Step 5: Add 0.45 g of Ancarez AR 550 (Air Products) and mix thoroughly. Add 0.05 g Surfynol 440. Mix thoroughly, homogenize if necessary.

The printable coating compositions of the invention can be applied to paper, polyester, vinyl, canvas, etc. using a suitable wire wound rod to achieve an approximate coat weight of 15 gsm. The coating typically is dried in an oven where the set point is 100° C.-150° C.