In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water and an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An ink jet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-receiving layer, and includes those intended for reflection viewing, which have an opaque support, and those intended for viewing by transmitted light, which have a transparent support.
An important characteristic of ink jet recording elements is their need to dry quickly after printing. To this end, porous recording elements have been developed which provide nearly instantaneous drying as long as they have sufficient thickness and pore volume to effectively contain the liquid ink. For example, a porous recording element can be manufactured by cast coating, in which a particulate-containing coating is applied to a support and is dried in contact with a polished smooth surface.
Ink jet prints, prepared by printing onto ink jet recording elements, are subject to environmental degradation. They are especially vulnerable to damage resulting from contact with water and atmospheric gases such as ozone. The damage resulting from the post imaging contact with water can take the form of water spots resulting from deglossing of the top coat, dye smearing due to unwanted dye diffusion, and even gross dissolution of the image recording layer. Ozone bleaches ink jet dyes resulting in loss of density. To overcome these deficiencies ink jet prints are often laminated. However, lamination is expensive since it requires a separate roll of material. Print protection can also be provided by coating a polymer solution or dispersion onto the surface of an ink jet element after the image is formed. The aqueous coating solutions are often polymer dispersions capable of film formation when water is removed. However, due to the wide variety of surface properties, it is difficult to formulate an aqueous polymer solution to be universally compatible to all ink jet receivers.
Alternatively, ink jet recording elements having a two layer construction, such as described in EP1078775A2, JP59222381 and U.S. Pat. No. 4,832,984 have been employed. These elements typically have a porous ink transporting topcoat of thermally fusible particles residing on either a swellable or porous ink-retaining layer. Upon printing, the ink passes through the topcoat and into an ink-retaining layer. The topcoat layer is then sealed to afford a water and stain resistant print. Such topcoats containing thermally fusible particles typically either contain a binder or are thermally sintered to provide a level of mechanical integrity to the layer prior to the imaging and fusing steps.
JP 256099694 discloses an ink jet recording element wherein the image-receiving layer contains latex or wax particles of 0.1 to 5.0 μm in diameter. While this recording element has a porous surface, the image-receiving layer has very poor integrity and tends to powder off the support which creates image defects.
EP 0858905A1 discloses the preparation of a recording medium comprising a porous outermost layer by coating and drying a particulate thermoplastic resin above its glass transition temperature (Tg), but below its minimum film formation temperature (MFFT). However, there is a problem with this element in that the drying temperature has to be controlled very precisely between the Tg and MFFT in order to achieve the desired result.
EP 0858906 relates to a base material, a porous ink-receiving layer and a porous surface layer having good ink capacity. However, it would be desirable to obtain good ink capacity without the need of using a separate ink-receiving layer.
It is an object of this invention to provide a novel porous ink jet recording element that absorbs inks instantly, and after imaging, provides an image which has good quality and is water and abrasion resistant. It is another object of the invention to provide a porous ink jet recording element which is easy to manufacture.