This invention relates to macroporous ink receiving media that provide durable high quality images with pigmented inks deposited thereon.
Inkjet and spray jet printing using dye-based inks is one method of manufacturing printed porous substrates such as textiles. Printed dyes may be xe2x80x9cfixedxe2x80x9d with dye mordants to improve waterfastness. Inkjet printing is well-suited for, among other things, short printing run and high resolution applications.
Pigment-based inks are commonly applied to porous substrates such as textiles by screen-printing methods, and are typically more durable than dye-based inks. In order to retain the pigment on the textile, a binder resin is employed to provide a means for anchoring the pigment to the textile. Screen-printing inks have viscosities that far exceed the maximum viscosities that may be successfully printed by inkjet methods. Additionally, the binder resins used in screen inks generally lend a stiffer (i.e., aesthetically undesirable) hand to the textile than if the same textile had been dyed. Screen printing is not a technology well-suited to short run printing in that a considerable effort is required to change screens and/or ink colors.
Dye-based inks generally suffer from poor stability compared to pigment-based inks, especially when lightfastness and waterfastness are considered.
There exists a need to provide durable lightfast and waterfast articles that combine the advantages of lightfastness, waterfastness, soft hand, and high resolution.
One aspect of the present invention is an ink receiving medium comprising a macroporous substrate having a pigment management system and a fluid management system in contact with surfaces of macropores of the substrate therein.
Another aspect of the present invention is an ink receiving medium comprising a macroporous substrate impregnated with a composition comprising one or more water-soluble multivalent metal salts together with a surfactant or a combination of surfactants for the ink and substrate being employed.
Another aspect of the present invention is an ink receiving medium comprising a macroporous substrate having a pigment management system and an optional fluid management system wherein the pigment management system is a non-aqueous solvent soluble metal salt.
The novel ink receiving media when imaged using an inkjet printer provide durable, high color intensity and high quality images which are tack-free and rapidly dry to the touch.
In another aspect, the present invention provides an ink receiving medium/ink set comprising a macroporous substrate impregnated with one or more multivalent water-soluble metal salts and a surfactant or combination of surfactants, and an ink that contains pigment colorants.
The ink receiving media of the invention provide images having improved durability, waterfastness, smear resistance, rapid dry times, and long term durability using a macroporous substrate without absorptive polymeric binders, or additional processes such as UV exposure or heating.
In a preferred embodiment, the ink colorant is a pigment dispersion having a dispersant bound to the pigment that will destabilize, flocculate, agglomerate, or coagulate on contact with the ink receiving medium. Upon deposition of ink at or just below the surface of the macroporous substrate, the fluid management system wicks the ink into the fibers or macropores where the pigment management system fixes (i.e., immobilizes) the pigment.
A feature of the present invention is the ability to xe2x80x9cfine tunexe2x80x9d the properties of the ink receiving media of the present invention to deal with the variables of inkjet ink delivery, including without limitation: drop volume, ink surface tension, porosity of the ink receiving medium, and capacity of the ink receiving medium to receive ink.
Other features of ink receiving media of the invention include that they: are cost competitive, work with pigmented inks, have high resolution, have high color density, provide wide color gamut, are waterfast, are smudge resistant, and provide rapid drying.
An advantage of ink receiving media of the present invention is that a laminated protective cover layer is not necessary to achieve water resistant images.
Another advantage of ink receiving media of the present invention is the ability to use inexpensive readily available materials in printing processes to produce images on, for example, custom papers such as real or simulated ragstock, textile fabrics, spunbonded fiber media, melt-blown microfiber (i.e., BMF) media, polyethylene envelope mailers and the like.
Another advantage of ink receiving media of the present invention is very fast drying of the pigment and fluid management systems during coating or impregnation. The process saves significant amounts of energy and thus, reduces costs.
As used herein, a xe2x80x9cmacroporous substratexe2x80x9d means a substrate having an average pore size of from about 3 xcexcm up to about 5 millimeters, preferably from about 10 xcexcm to about 2 millimeters, more preferably from about 100 xcexcm to about 0.5 millimeter and does not include microporous films and particles. In addition, the macroporous substrates of the invention are characterized by having a solidity of from at least about 1 percent up to about 90 percent, preferably from at least about 5 percent to about 70 percent, and even more preferably from at least about 10 percent up to about 50 percent.
As used herein, a xe2x80x9cpigment management systemxe2x80x9d means a composition comprising a metal salt that has coated or impregnated a substrate to prepare an ink receiving medium suitable for use in the process of inkjet printing.
As used herein, a xe2x80x9cfluid management systemxe2x80x9d means a composition comprising at least one surfactant that has coated or impregnated a substrate to prepare an ink receiving medium suitable for use in the process of inkjet printing.
The term xe2x80x9carithmetic median fiber diameterxe2x80x9d means the fiber diameter for which equal numbers of fibers have diameters that lie above or below this value. The arithmetic median fiber diameter can be determined through microscopic examination.
The term xe2x80x9csolidityxe2x80x9d means the volume of fibers per volume of web. It is a unitless fraction typically represented by xcex1:   α  =            m      f                      P        f            ⁢              xe2x80x83            ⁢              L        f            
where mf is the fiber mass per sample surface area; Pf is the fiber density; and Lf is the macroporous substrate thickness. Solidity is used herein to refer to the macroporous substrate itself and not to any composite structure in which it may be included as a component thereof. When a macroporous substrate contains mixtures of two or more kinds of fibers, the individual solidities are determined for each kind of fiber using the same Lf. The individual solidities are added together to obtain the web""s solidity, xcex1w.
The term xe2x80x9caverage pore sizexe2x80x9d (also known as average pore diameter) is related to the arithmetic median fiber diameter and web solidity and can be determined by the following formula:   D  =            d      f        ⁢          {              xe2x80x83            ⁢                                    (                                          2                ⁢                                  xe2x80x83                                ⁢                                  α                  w                                            π                        )                                              -              1                        /            2                          -        1            }      
where D is the average pore size, df is the arithmetic median fiber diameter, and xcex1w is the web solidity.