WO2018156811A1

WO2018156811A1 - Single layer coated inkjet-printable media with improved gloss

Info

Publication number: WO2018156811A1
Application number: PCT/US2018/019290
Authority: WO
Inventors: Datta G. Mislankar; Jason A. MORGAN; Michael Allen PETRI
Original assignee: Appvion, Inc.
Priority date: 2017-02-22
Filing date: 2018-02-22
Publication date: 2018-08-30

Abstract

An inkjet-receptive, glossy recording medium is produced by forming a single-layer coating on one or both major surfaces of a paper substrate or the like. The single-layer coating includes at least colloidal silica and hollow polymeric spheres, and it is preferably porous to inkjet inks both before and after calendering or supercalendering. The manufacturing cost of the product can be reduced by forming the coating on a given side of the substrate in a single coating pass with a single coating head, and by using a composition for the coating in which expensive conventional components are replaced in whole or in part with less expensive components.

Description

SINGLE LAYER COATED INKJET-PRINTABLE MEDIA WITH IMPROVED GLOSS

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to provisional patent application USSN 62/462,030, "Single Layer Coated Inkjet Printable Media With Improved Gloss", filed Februar 22, 2017,

FIELD OF THE INVENTION

The present invention relates to coated papers or other coated substrates in which the coating is both glossy, and adapted for inkjet receptivity. The invention also pertains to related methods, systems, and articles.

BACKGROUND OF THE INVENTION

High-speed industrial inkjet printing machines of web press systems, whose printing speed is 120 m/min, are known. Some of these high-speed industrial printing machines use water-based dye inks, while others use water-based pigment inks.

Numerous types of coated printing papers are also known, some of which are suitable for use in such high-speed industrial inkjet printing machines. Water-based dye inks need coated printing papers that yield high color densities and vivid color tone, and that prevent the inks from bleeding when the paper is exposed to humid conditions. Water-based pigment inks need coated printing papers that yield improved scratch or abrasion resistance of printed images on the paper, and elimination or reduction of uneven printing.

The currently available coated printing papers suitable for use in high speed industrial inkjet printing machines provide a variety of tradeoffs between performance and cost. There is a need for new types of inkjet-printable recording media, including coated printing papers, that can provide good performance characteristics in high-speed inkjet printing applications using different, lower-cost formulations and product constructions.

SUMMARY OF THE INVENTION We have developed a new family of inkjet-prin table recording media that can help satisfy this need. The new recording media provide a thin, flexible sheet-like material whose outer surface is both inkjet-receptive and glossy, in a product construction that can be produced by forming a single-layer coating on one or both major surfaces of a paper substrate or the like. The single-lay er coating may include at least colloidal silica and a pigment material of hollow polymeric spheres. The gloss of the surface can be produced by calendering, or supercalendering, the intermediate or precursor coated product, and the composition of the coating is preferably selected such that the coating is porous to inkjet inks both before and after calendering. The manufacturing cost of the product can be reduced by forming the single-layer coating on a given side of the substrate in a single coating pass with a single coating head, and by using a composition for the coating in which expensive conventional components are replaced in whole or in part with less expensive components.

We therefore disclose herein, among other things, recording media that include a substrate having a first major surface, and a first single-layer coating on the first major surface. The first coating preferably includes colloidal silica and hollow polymeric spheres, and the first coating is inkjet receptive.

The first coating may have a first gloss (TAPPI T 480, 75°) in a range from 55 to 80 or from 55 to 75, or may be adapted to provide the first gloss upon calendering of the recording medium. The first coating may have the first gloss in the range from 55 to 80 or from 55 to 75, and may be porous to an inkjet ink. The first coating may provide a first print density for black inkjet ink in a range from 1 .4 to 2, or may be adapted to provide the first print density upon calendering of the recording medium. The substrate may comprise, or consist essentially of, or consist of, an absorbent paper stock, and the absorbent paper stock may include a sizing agent treatment. The substrate may also have a second major surface opposite the first major surface, and the recording medium may further include a second single-layer coating on the second major surface, and the second coating may be inkjet receptive and include colloidal silica and hollow polymeric spheres. The first coating may have a first gloss in a first range from 55 to 80 or 55 to 75 (TA PPI T 480, 75°), or may be adapted to provide the first gloss upon calendering of the recording medium, and the second coating may have a second gloss in a second range from 55 to 80 or 55 to 75 (TAPPI T 480, 75°), or may be adapted to provide the second gloss upon calendering of the recording medium. The recording medium may consist essentially of, or consist of, the substrate, the first coating, and the second coating.

The first coating may have no more than 20% (TDS) of a fumed metal oxide. The first coating may further have less than 5% (TDS), or substantially no, fumed alumina. The first coating may include colloidal silica in a range from 40 to 70%, or 40 to 50% (TDS). The hollow polymeric spheres may be present in the first coating in a range from 5 to 30% or from 10 to 30% (TDS). The hollow polymeric spheres may have an average diameter in a range from 0.5 to 1 ,6 micrometers. The first coating may also include at least one of a dye fixing agent, a fumed silica, and a binder, or it may include each of the dye fixing agent, the fumed silica, and the binder.

We also disclose methods of making inkjet receptive, glossy recording media. Such methods may include: providing a substrate having a first major surface; coating a first material onto the first major surface to provide a first single-layer coating, the first material including colloidal silica and hollow polymeric spheres; drying the first coating; and calendering the coated substrate to render the first coating inkjet receptive and glossy, the first coating having a first gloss (TAPPI T 480, 75°) in a range from 55 to 80, or from 55 to 75.

The coating may be accomplished with only one coating head and in only one pass of the substrate. The first coating may be porous to an inkjet ink before and after the calendering. After the calendering, the first coating may provide a first print density for black inkjet ink in a range from 1.4 to 2, The substrate may comprise, or consist essentially of, or consist of, an absorbent paper stock. The absorbent paper stock may include a sizing agent treatment. The substrate may also have a second major surface opposite the first major surface, and the method further include: coating a second material onto the second major surface to provide a second single-layer coating, the second material comprising colloidal silica and hollow polymeric spheres; and drying the second coating; and the calendering may also render the second coating inkjet receptive and glossy, the second coating having a second gloss (TAPPI T 480, 75°) in a range from 55 to 80, or from 55 to 75,

After the drying, the first coating may have no more than 20% (TDS) of a fumed metal oxide, or less than 5% (TDS), or substantially no, fumed alumina. After the drying, the first coating may include colloidal silica in a range from 40 to 70%, or from 40 to 50% (TDS). After the drying, the hollow polymeric spheres may be present in the first coating in a range from 5 to 30% (TDS), or in a range from 10 to 30% (TDS). The hollow polymeric spheres may have an average diameter in a range from 0.5 to 1.6 micrometers. The first material may further include at least one of a dye fixing agent, a fumed silica, and a hinder, or it may include each of the dye fixing agent, the fumed silica, and the binder.

Numerous related methods, systems, and articles are also disclosed.

These and many other aspects of the present disclosure will be apparent from the detailed description below. In no event, however, should the above summaries be construed as limitations on the claimed subject matter, which subject matter is defined solely by the attached claims, as may be amended during prosecution.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive articles, systems, and methods are described in further detail with reference to the accompanying drawings, of which:

FIG. 1 A is a schematic front elevation view, which also serves as a schematic cross- sectional view, of a substrate for use with the disclosed recording media;

FIG. B is a schematic front elevation view, or cross-sectional view, of a low-gloss recording medium, made by forming on one major surface of the substrate of FIG. 1A a single- layer coating of a particular composition;

FIG. IC is a schematic front elevation view, or cross-sectional view, of a higher-gloss recording medium, made by supercalendering the recording medium of FIG. IB;

FIG. I D is a schematic front elevation view, or cross-sectional view, of another high- gloss recording medium similar to that of FIG. IC, but where a single-layer coating is provided on both major surfaces of the substrate; and

FIG. 2 is a schematic diagram of a single-pass, single-head coating system suitable for forming the single-layer coating on a given side of the substrate.

In the figures, like reference numerals designate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

As noted above, we have developed a new family of inkjet-printable recording media that are suitable for use in high-speed, e.g. 120 m/min, industrial inkjet printing machine applications, and optionally in other inkjet printing applications. The disclosed recording media preferably employ a simple, economical single-layer coating on one or both major surfaces of a paper stock or other substrate. The single-layer coating, in turn, makes preferential use of relati vely inexpensive ingredients or components that have nevertheless been found to give good performance characteristics. A precursor recording medium is made by simply drying the single- layer coating in place on the substrate, whereupon the coating provides an Inkjet receptive surface but a low gloss. A finished recording medium can then be made by calendering or supercalendering the precursor recording medium. This operation substantially improves the inkjet receptivity, increases the gloss, and maintains the porosity of the coating to inkjet inks, which is a surprising technical feat in view of the fact that supercalendering is commonly known to close off the surface of a coating, and prevent it from properly receiving ink. The balance achieved between high gloss and good print performance after calendering is surprising.

Recordable media are shown in various stages of production in FIGS. 1 A through ID. The production process may begin with the selection of a suitable substrate. Such a substrate 110 is shown in FIG. 1A. The substrate 110 is preferably thin, substantially planar, and flexible. The substrate 110 has a thickness defined by opposed major surfaces 110a, 110b. The substrate may preferably be or comprise a cellulose material, such as a conventional paper. In some of our work. Triumph brand Ultra P grade paper, available from Appvion, Inc., was found to be particularly useful. This paper has a basis weight of 89.5 g/m , and is treated with CaCl₂ surface sizing agent.

However, other paper products have also been found to be suitable. Uncoated base papers, including unsized, conventionally sized, and lightly treated base papers, can be used. Some papers may be treated with, for example, colloidal silica dispersion or cationic polymer. The substrate 110 is preferably simple in construction, and devoid of glossy coatings, or of other substantial, functional coatings. The substrate 110 may, for example, be substantially uniform in composition throughout its thickness, rather than a multilayered construction or material to which one or more separate, functional coatings have already been applied. In some cases, however, it may be desirable to treat, prepare, or otherwise work the substrate 110 in preparation for the coating step(s) that follow. The substrate 110 and its major surfaces are also typically light-diffusive in character, with no noticeable gloss properties.

After the substrate 110 is selected and optionally prepared, a liquid coating material is applied to one or both major surfaces 110a, 110b of the substrate 110, depending on whether Inkjet printabiliiy, and high gloss, is desired on one or both sides of the finished product. In FIG. IB, the substrate 110 is shown after such a coating material has been coated onto the major surface 110a, and then dried, to form a coating 112 on the major surface 110a. The coating 112 is in the form of a single layer, and preferably of substantially uniform composition throughout its thickness. The coated substrate, as shown in FIG. I B, is an intermediate product 120 or precursor to the final recording medium: upon carrying out a further processing step discussed below in connection with FIG. 1 C, the single-layer coating 112 is changed to provide in the final recording medium a high gloss and an outer surface that is receptive to inkjet inks. Before that processing step, the (unprocessed) intermediate product 120 exhibits a low gloss on the side of the coating 112, i.e., on the side of the exposed major surface 112a of the coating 112, which is coincident with the exposed major surface 120a of the intermediate product 120. By

appropriately selecting the composition of the liquid coating material, the (dry) coating 112 exhibits a porosity to inkjet inks that renders it inkjet receptive, although with print performance characteristics such as resolution that are not as advanced as those of the fini shed product.

Nevertheless, in view of the fact that the intermediate product 120, as-is, is useable as an inkjet recording medium, the intermediate product 120 can also be referred to as an intermediate recording medium 120, or more simply as a recording medium 120.

The composition of the liquid coating material is desirably selected to provide a highly glossy appearance, and a high performance inkjet receptivity, e.g., compatible with high-speed industrial inkjet printing machines, on the coated side(s) of the finished product. In this regard, the liquid coating material preferably includes colloidal silica and a hollow polymeric sphere pigment material. The hollow polymeric sphere pigment material may be or comprise Ropaque brand TH 1000 pigment available from The Dow Chemical Company, or any of the other Ropaque brand of pigments, or the like. The hollow polymeric sphere pigment may have an average particle size of 1 micrometer, or in a range from 0,5 to 1.6 micrometers. The hollow polymeric sphere pigment may also have a void volume of 55%, or in a range from 50 to 60%,

Although colloidal silica is highly beneficial in the disclosed coatings, it is also quite expensive. We have found that the material cost of the product can be substantially reduced by lowering the amount of colloidal silica and increasing the amount of the hollow polymeric spheres, or certain other materials such as dye fixing agents and binders. One class of dye fixing agents of interest include Cartafix brand fixing agents offered by Archroma Packaging & Paper Specialties. Fumed metallic oxides, including particularly fumed alumina, are other materials that are highly useful in the disclosed coatings, but they too are relatively expensive. We have found it possible to achieve good operational performance in the disclosed inkjet-printable recording media with the use of no, or substantially no, fumed alumina, fumed silica, or other fumed metal oxides, or by using no more than 5% (TDS), or no more than 10% (TDS), or no more than 20% (TDS) of fumed alumina, fumed silica, or any other fumed metal oxide. Besides the components already mentioned, the disclosed single-layer coatings can also include other functional components such as crosslinkers, defoamers, fillers, surfactants, optical brighteners, and rheology modifiers.

As noted above, the as-coated, but dried, coating 112 on the intermediate recording medium 120 exhibits porosity to inkjet inks, a low level of gloss, and moderate inkjet receptivity. The gloss of the coating 112 may typically be less than 35, or in a range from 30 to 35.

With regard to gloss: these and other gloss values reported throughout the specification and claims refer to values obtained using the known TAPPI T 480 standard at a 75 degree angle, unless otherwise indicated. Higher gloss values, and higher performance inkjet receptivity, can be obtained by subjecting the intermediate recording medium 120 to a calendering operation, or more specifically to a supercalendering operation, which can be considered a form of

calendering. We have found that a balance involving the composition of the coating 112 and the conditions of the supercalendering can be achieved such that the supercalendering, while being effective to increase gloss, does not close off the surface of the coating. Consequently, the coating remains porous to inkjet inks, and provides enhanced inkjet receptivity.

In laboratory experiments of samples disclosed herein, three laboratory-scale calender nips at settings of 2000 pounds per square inch (psi) were found to produce acceptable results. Larger scale calendering studies were also done to produce a translation between the laboratory calender settings (in psi) and the settings of a large scale, industrial-sized calender, given in pounds per linear inch (pli). Settings of 1000 to 2000 pli with four calender nips on the large scale calender was found to provide inkjet print quality comparable to that of the laboratory calender machine, however— the gloss values exhibited by samples calendered on the large scale calender were found to be consistently higher by 8 to 10 points than the gloss values of counterpart samples calendered on the laboratory calender. Figure I C illustrates the resulting finished recording medium 120' that results from subjecting the intermediate recording medium 120 to the supercalendering process. Reference numbers in this figure have corresponding reference numbers in FIG. I B, except that the reference numbers in FIG. IC include a prime symbol, as in 120', to indicate these elements have been permanently modified by the compression forces of the calendering process. As modified, the finished or final recording medium 120' exhibits a high degree of gloss and a high performance Inkjet receptivity on the side of the coating 112', i.e., on the side of the exposed major surface 112a' of the coating 112', which is coincident with the exposed major surface 120a' of the finished product 120'.

The gloss value of the coating 112' is preferably in a range from 55 to 80, or 55 to 75 (TAPPI T 480, 75°). Gloss values substantially outside of this range, whether below 55 or 50, or above 80, may be suitable for some market segments, but are not suitable for the market segment of interest , namely, recording media for high speed industrial inkjet printers. The inkjet recepti vity of the coating 112' may be characterized by one or more of a number of specific print performance tests, including print density, line bleed, dot gain, smudge rating, and dryness rating. These are discussed in more detail below.

The (dry) coating 112' of the recording medium 120' preferably exhibits porosity to inkjet inks, in spite of the calendering process. The opposite side of the product 120', at major surface 110b', exhibits the typical low gloss inherent with the base stock used as the substrate 110', and may or may not exhibit any degree of inkjet receptivity.

In many product applications, symmetrical product configurations are desirable. This is also true with regard to many types of papers, coated papers, and similar flexible sheet-like products, since printing is often desired on both sides of such products. Consequently, we also contemplate recording media similar to those of FIGS. IB and IC, but where a single-layer coating is provided on each of the two major surfaces 110a, 110b of the substrate 110, rather than on only one major surface. Such a recording medium 122' is shown in FIG. ID. The recording medium 122' may exhibit mirror symmetry about a reference plane parallel to the plane of the substrate 110' and equidistant from the major surfaces 1.10a', 110b'. The recording medium 122' may thus be the same as or similar to recording medium 120' of FIG. IC, except that during fabrication, liquid coating material was applied to both sides of the substrate, and both of the resulting single-layer coatings were dried before calendering the symmetrical intermediate recording medium to yield the finished, symmetrical recording medium 122' of FIG. ID. Such a product provides high gloss and Inkjet receptivity, as discussed above, on both sides, or at both major surfaces 112', 122a', and 114b', 122b' as shown.

Of course, in some cases, it may be desirable to deliberately make the coatings 112', 114' of recording medium 122' different from each other, resulting in an asymmetrical product construction. In some cases, for example, the coating 114' may have substantially the same composition but a substantially different thickness than the coating 112', In some cases, the coating 114' may have substantially the same thickness but a substantially different composition than the coating 112'. In some cases, the coating 114' may have both a substantially different thickness and a substantially different composition than the coating 112'.

Figure 2 is provided to illustrate a simple and relatively low-cost step in the

manufacturing process for the disclosed recording media. More particularly, FIG. 2

schematically illustrates a single -pass, single-head coating system 208 for forming a single-layer coating on a gi ven side of the substrate. In the system 208, a jumbo roll or other roll of substrate material 210 is unwound at an unwind station 230. The substrate 210 may be the same as or similar to substrate material 110 discussed previously. The substrate 210 may thus have a first major surface 210a and an opposed second major surface 210b. Conventional rollers and the like guide the substrate 210 along a film path which brings it in close proximity to a coating head 232. The coating head 232 includes or draws from a reservoir of the liquid coating material, and applies a layer of the coating material in a metered amount on the first major surface 210a of the substrate 210 to form a single-layer coating 212. The coating head 232 is shown schematically in the figure as a box, but it may be of any suitable design or type, such as a curtain coaler, a blade coater, a rod coater (including a Meier rod coater), or an air knife coater, for example. The coating 212 is then solidified in place on the surface 210a of the substrate 210 by passing the coated substrate 210 through a dryer 234, thus forming an intermediate recording medium 220. The recording medium 220 may be the same as or similar to the intermediate recording medium 120 discussed above. The recording medium 220 may then be wound up into a jumbo roll or other roll at a winding station 236.

To recap, the coating system 208 forms the single-layer coating 212 using a single pass of the substrate 210 past a single coating head 232. If desired, the system 208 can be readily modified to include a second coating head that deposits a second single-layer coating on the opposite major surface 210b of the substrate 210, before passing the substrate through the dryer 234, In either case, each single-layer coating on the substrate is formed using a single-pass of the substrate past a single coating head, and the (1 -side coated or 2-side coated) intermediate recording medium is wound up into a roll at the winding station 236. This simplified coating process and simplified product configuration can reduce manufacturing costs compared to recording media whose fabrication requires one, some, or all of: multiple coating layers; multiple coating heads; and multiple coating passes.

The roll of intermediate recording medium may then be transferred to a separate calendering system (supercalendering system), where the compression forces of the calender nip(s) permanently convert the low-gloss intermediate recording medium to a glossy, finished recording medium, such as the one-sided embodiment of FIG. 1C or the 2-sided embodiment of FIG. I D. Alternatively, the coating system 208 and the calendering system can in some cases be combined, such that an in-line calendering system is added to the film path of FIG. 2 between the dryer 234 and the winding station 236, whereupon the finished recording medium (rather than the intermediate recording medium) is collected at the winding station 236.

The final or finished recording medium can also if desired be con verted from a large, continuous roll good format into smaller, narrower rolls, or even individual pieces or sheets of desired sizes, by conventional converting techniques such as slitting and cutting.

The performance characteristics of a given surface or side of a recording medium as disclosed herein typically involve (a) an evaluation of the gloss of the surface itself, before any Inkjet ink is deposited onto the surface by a printer head, and (b) an evaluation of inkjet print performance, i.e., of the inkjet inks after being deposited onto the surface. The gloss

characteristic (a) is straightforward. As mentioned above, gloss values are reported herein using the known TAPPI T 480 standard at a 75 degree angle, unless otherwise indicated. Gloss values in a range from 55 to 80, or 55 to 75, are of greatest interest for the market segment targeted for the disclosed recording media. Gloss values substantially above or below these ranges are of little or no interest for this targeted market segment.

Performance characteristics relating to an evaluation of inkjet print performance are more complicated, because more than one performance characteristic is usually required, or desired, to adequately assess the degree to which the coating or surface can be considered truly inkjet receptive. Performance characteristics that are relevant to inkjet receptivity can include print density, line bleed, dot gain, smudge rating, and dryness rating. One objective of this testing is to evaluate the ability of the recording medium to be printed ai full production speeds in high speed industrial inkjet printing machines. The recording medium should handle the ink in a manner that enables high image density, high image resolution (such that an ink microdroplet remains in place on the recording medium where the printhead deposited it), and still have the ability for the surface to dry quickly so as to avoid smudging, bleed, or offsetting within the printed roll on the wind stand, or in a sheet stack when printed in sheet form.

With regard to the print performance characteristic of "print density": separate, solid patches of the four individual inkjet colors— cyan (C), magenta (M), yellow (Y), and black (K)— are printed on the surface of the recording medium. After printing, the ink density of each color is measured using a spectrodensitometer. Density values are given in units of optical density (OD), with higher values generally being more desirable. The four ink density values can also be averaged to yield a single representative average print density value.

With regard to the print performance characteristics of "line bleed" and "dot gain": line bleed is a commonly used diagnostic that measures how much two colors, printed right next to each other, bleed into one another to degrade image resolution. This may be a visual evaluation based on a control set of known standards. Dot gain is a similar test, which measures how a printed area can look darker than intended because the printed dots bleed into the unprinted white space that should exist between the printed dots. The line bleed and dot gain characteristics both measure the degree to which a microdroplet of inkjet ink stays on the surface in the place it was printed.

With regard to the print performance characteristics of "smudge rating" and "dryness rating": these are both measurements of how quickly the inkjet ink dries on the surface. The practical need is for the ink to dry sufficiently so as not to smudge the print, or have it offset onto adjacent sheet(s) in a wound roll or a stack of discrete sheets. In the case of the smudge rating, blocks of ink are printed on the recording medium, and the degree to which the image can be smudged with a device replicating a fingertip is measured visually against control images. This smudge test is performed at a fixed time after printing. The dryness rating is similar to the smudge rating, except that consecutive smudge tests are performed on a solid black print square at predetermined times of 5, 10, 15, 30, 60, and > 60 seconds after printing. The outcome of the diyness rating is the time at which the image is diy enough to avoid smudging beyond a predetermined amount.

In most cases, a given recording medium or coating thereof may be considered inkjet receptive if the print perfomiance characteristics of the given medium or coating are at least comparable to corresponding print performance characteristics of commercially available inkjet- printable recording media,

EXAMPLES

In accordance with the foregoing teachings, a number of recording media samples were fabricated and tested,

A first group of liquid coating materials were prepared, each of which was then used to form a single-layer coating on a paper substrate, and then supercalendered, to provide an inkjet- printable recording medium. The ingredients used for the various liquid coating materials are shown in Table 1; however, the number provided in each cell of Table 1 represents the percent total dry solids (TDS) of the given material that was present in the dry coating. In the table, the abbreviations have the following meanings:

• AA130 = Aeroxide Alu 130, a fumed alumina material

• BA = boric acid, a PVA crosslinker

• CGH = Cartabond GH Liquid, a PVA crosslinker

® LCLP = Ludox CL-P, a colloidal silica material, nominal particle size 22 nm

» RRM = Rheocarb RM 232D, a rheology modifier

» RTH ===^: Ropaque TH-1000, a hollow polymeric sphere pigment material from The Dow Chemical Company, 1.0 micron average size

• S540 = Selvol 540, a PVA binder

• SC809 = Syloid C809, a silica matting agent

TABLE 1

T2-3 10 0.625 0.1 89.025 0.25

T2-4 15 0.625 0.1 84.025 0.25

T2-5 20 0.625 0.1 79.025 0.25

T2-6 30 0.625 0.1 69.025 0.25

T3-1 15 0.1 81.775 1 2.5

T4-1 0.625 0.1 79.025 10 0.25 10

T4-2 10 0.625 0.1 79.025 10 0.25

T4-3 10 0.625 0.1 79.025 0.25

In using the formulations of Table 1 to make inkjet-printable recording media, Triumph brand Ultra P grade paper, available from Appvion, Inc. was used as the substrate (see e.g. FIG. 1). This material has a basis weight of 89.5 granis/ni², and is treated with a CaCl₂ sizing agent. Each of the liquid coating materials defined in Table 1 was coated as a single layer onto a major surface of the substrate using a laboratory Meier rod hand coating process, with a Weight of Coat (WOC), in pounds per (book or offset) ream (25" x 38" x 500 sheets), as reported in Table 2. The coating was then dried to provide an intermediate recording medium. The thickness of the dry coating is given in Table 2. Then, the coated substrate was supercalendered using a laboratory calender device having 3 calender nips at a setting of 2000 psi, which was determined to be optimal for that laboratory device. Measured gloss values of the coating after calendering are also provided in Table 2. To obtain print performance characteristics, each sample was printed using an Epson C88+ desktop Inkjet printer, which used a water-based pigment ink set comparabl e to that of typical commercial web format printing presses. The measured print performance characteristics are also provided for the various constnictions of Table 2, In that regard, SR. refers to the smudge rating. The smudge rating is given on a scale of 0-5, with 0 being excessive smudge and 5 being no smudge.

FABLE 2

With regard to the gloss values reported in Table 2 above and in Table 4 below, the reader should keep in mind the discussion above regarding gloss values of samples calendered on the large scale calender versus those of samples calendered on the laboratory calender - samples calendered on the large scale calender consistently exhibit gloss levels 8 to 10 points higher than counterpart samples calendered on the laboratory calender, whereas the inkjet print quality is comparable. In view of the limi ted availability of the large-scale calender for experimental tests, the laboratory calender was used to fabricate the Inkjet-printable recording media examples whose properties are reported in Tables 2 and 4. Consequently, one can expect to obtain gloss values 8 to 10 points higher than those reported in those Tables 2 and 4 if calendering of the samples is done on the large scale calender.

A second group of liquid coating materials were prepared, each of which was then used to form a single-layer coating on a paper substrate, and then superealendered, to provide an inkjet-printable recording medium. The ingredients used for the various liquid coating materials are shown in Table 3; however, the number provided in each cell of Table 1 represents the percent total dry solids (TDS) of the given material that was present in the dry coating. In the table, the abbreviations have the following meanings:

• A2 = Aerosil 200, a fumed silica material

• AA130 = Aeroxide Alu 130, a fumed alumina material

• B A = boric acid, a PVA crosslinker

• C = Carbowet GA-211, a surfactant

® CGH = Cartabond GH Liquid, a PVA crosslinker

• CVX = Cartafix VXZ, a cationic dye fixing agent

• FM = FM VF, a defoamer

® FP = FP-300 CS, a treated calcium carbonate material

® LE = Leucophor SAC, an optical brightener

• LCLP = Ludox CL-P, a colloidal silica material, nominal particle size 22 nm

• Om = OmyaJet 5010, a calcium carbonate precipitate

• PA = Paranol AC-7072, a styrene acrylic emulsion - binder

® P3 = Povai 3-85, a polyvinyl alcohol RTH = Ropaque TH-1000, a hollow polymeric sphere pigment material from The Dow Chemical Company, 1.0 micron average size

R2 = Ropaque TH-2000AF, a hollow polymeric sphere pigment material from The

Dow Chemical Company, 1.6 micron average size

S540 = Seivoi 540, a PVA binder

SDF = Surfynol DF-37, a defoamer

TJXA = Topsperse JX A, a rheology modifier

TABLE 3

In using the formulations of Table 3 to make inkjet-prin table recording media, Triumph brand Ultra P grade paper, available from Appvion, Inc. was again used as the substrate. Each of the liquid coating materials defined in Table 3 was coated as a single layer onto a major surface of the substrate using a laboratory Meier rod hand coating process, with a Weight of Coat (WOC), in pounds per (book or offset) ream (25 inches x 38 inches x 500 sheets), as reported in Table 4. The coating was then dried to provide an intermediate recording medium. Then, the coated substrate was supercalendered using a laboratory calender device having 3 calender nips at a setting of 2000 psi, which was determined to be optimal for that laboratory device. Measured gloss values of the coating after calendering are also provided in Table 4. To obtain print performance characteristics, each sample was printed using an Epson C88+ desktop Inkjet printer, which used a water-based pigment ink set comparable to that of typical commercial web format printing presses. The measured print performance characteristics are also provided for the various constractions of Table 4. In that regard, SR refers to the smudge rating, and DR refers to the dryness rating. The smudge rating is given on a scale of 0-5, with 0 being excessive smudge and 5 being no smudge. The dryness rating is given on a scale of 0-5, where 5 means drying occurred in < 5 sec, 4 means < 10 sec, 3 means < 15 sec, 2 means < 30 sec, 1 means < 60 sec, and 0 means > 60 seconds.

TABLE 4

COMPARATIVE EXAM PLE

A commercially available inkjet-printable recording medium product, Sword iJET 4.3 Gloss, sold by Mitsubishi Imaging (M PM), Inc., was tested for coating thickness, gloss, print density, and other print performance characteristics. The results are given in Table 5,

TABLE 5

Unless otherwise indicated, all numbers expressing quantities, measured properties, and so forth used in the specification and claims are to be understood as being modified by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations thai can vary depending on the desired properties sought to be obtained by those skilled in the art uti lizing the teachings of the present application. Not to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the in vention are approximations, to the extent any numerical values are set forth in specific examples described herein, they are reported as precisely as reasonably possible. Any numerical value, however, may well contain errors associated with testing or measurement limitations.

The use of relational terms such as "top", "bottom", "upper", "lower", "above", "below", and the like to describe various embodiments are merely used for convenience to facilitate the description of some embodiments herein. Notwithstanding the use of such terms, the present disclosure should not be interpreted as being limited to any particular orientation or relative position, but rather should be understood to encompass embodiments having any of orientations and relative positions, in addition to those described above.

Various modifications and alterations of this invention will be apparent to those skilled in the art without departing from the spirit and scope of this invention, which is not limited to the illustrative embodiments set forth herein. The reader should assume that features of one disclosed embodiment can also be applied to all other disclosed embodiments unless otherwise indicated. All U.S. patents, patent application publications, and other patent and non-patent documents referred to herein are incorporated by reference, to the extent they do not contradict the foregoing disclosure.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A recording medium, comprising:

a substrate having a first major surface; and

a first single-layer coating on the first major surface;

wherein the first coating comprises colloidal silica and hollow polymeric spheres; and wherein the first coating is inkjet receptive.

2. The recording medium of claim 1 , wherein the first coating has a first gloss (TA PPI T 480, 75°) in a range from 55 to 80, or is adapted to provide the first gloss upon calendering of the recording medium.

3. The recording medium of claim 2, wherein the first coating has the first gloss in the range from 55 to 80, and wherein the first coating is porous to an inkjet ink.

4. The recording medium of claim 1, wherein the first coating provides a first print density for black inkjet ink in a range from 1.4 to 2, or is adapted to provide the first print density upon calendering of the recording medium.

5. The recording medium of claim 1 , wherein the substrate comprises, or consists essentially of, or consists of, an absorbent paper stock.

6. The recording medium of claim 5, wherein the absorbent paper stock comprises a sizing agent treatment.

7. The recording medium of claim 1 , wherein the substrate also has a second major surface opposite the first major surface, and the recording medium further comprises:

a second single-layer coating on the second major surface;

wherein the second coating comprises colloidal silica and hollow polymeric spheres; and wherein the second coating is inkjet receptive,

8. The recording medium of claim 7, wherein the first coating has a first gloss in a first range from 55 to 80 (TAPPI T 480, 75°), or is adapted to provide the first gloss upon calendering of the recording medium, and the second coating has a second gloss in a second range from 55 to 80 (TAPPI T 480, 75°), or is adapted to provide the second gloss upon calendering of the recording medium.

9. The recording medium of claim 7, wherein the recording medium consists essentially of, or consists of, the substrate, the first coating, and the second coating.

10. The recording medium of claim 1 , wherein the first coating has no more than 20% (TDS) of a fumed metal oxide.

11. The recording medium of claim 10, wherein the first coating has less than 5% (TDS), or substantially no, fumed alumina.

12, The recording medium of claim 1, wherein the first coating comprises colloidal silica in a range from 40 to 70% (TDS).

13. The recording medium of claim 12, wherein the first coating comprises colloidal silica in a range from 40 to 50% (TDS).

14. The recording medium of claim 1, wherein the hollow polymeric spheres are present in the first coating in a range from 5 to 30% (TDS), or in a range from 10 to 30% (TDS),

15, The recording medium of claim 14, wherein the hollow polymeric spheres have an average diameter in a range from 0.5 to 1.6 micrometers.

16. The recording medium of claim 1 , wherein the first coating further comprises at least one of a dye fixing agent, a fumed silica, and a binder,

17. The recording medium of claim 16, wherein the first coating comprises the dye fixing agent, the fumed silica, and the binder.

18. A method of making an inkjet receptive, glossy recording medium, comprising:

providing a substrate having a first major surface;

coating a first material onto the first major surface to provide a first single-layer coating, the first material comprising colloidal silica and hollow polymeric spheres;

drying the first coating; and

calendering the coated substrate to render the first coating inkjet receptive and glossy, the first coating having a first gloss (TAPPI T 480, 75°) in a range from 55 to 80.

19. The method of claim 18, wherein the coating is accomplished with only one coating head and in only one pass of the substrate.

20. The method of claim 18, wherein the first coating is porous to an inkjet ink before and after the calendering.

21. The method of claim 18, wherein after the calendering, the first coating provides a first print density for black inkjet ink in a range from 1.4 to 2.

22. The method of claim 18, wherein the substrate comprises, or consists essentially of, or consists of, an absorbent paper stock.

23. The method of claim 22, wherein the absorbent paper stock comprises a sizing agent treatment.

24. The method of claim 18, wherein the substrate also has a second major surface opposite the first major surface, and the method further comprises: coating a second material onto the second major surface to provide a second single-layer coating, the second material comprising colloidal silica and hollow polymeric spheres; and

drying the second coating;

wherein the calendering also renders the second coating inkjet receptive and glossy, the

second coating having a second gloss (TAPPI T 480, 75°) in a range from 55 to 80.

25. The method of claim 18, wherein, after the drying, the first coating has no more than 20% (TDS) of a fumed metal oxide.

26. The method of claim 25, wherein, after the drying, the first coating has less than 5% (TDS), or substantially no, fumed alumina.

27. The method of claim 18, wherein, after the drying, the first coating comprises col loidal silica in a range from 40 to 70% (TDS).

28. The method of claim 27, wherein, after the drying, the first coating comprises colloidal silica in a range from 40 to 50% (TDS).

29. The method of claim 18, wherein, after the drying, the hollow polymeric spheres are present in the first coating in a range from 5 to 30% (TDS), or in a range from 10 to 30% (TDS).

30. The method of claim 29, wherein the hollow polymeric spheres have an average diameter in a range from 0,5 to 1.6 micrometers.

31. The method of claim 18, wherein the first material further comprises at least one of a dye fixing agent, a fumed silica, and a binder,

32. The method of claim 31, wherein the first material comprises the dye fixing agent, the fumed silica, and the binder.