MXPA05013933A - Pigment for use in inkjet recording medium coatings and methods - Google Patents

Abstract

Pigment suitable for us in coating compositions for inkjet recording media. Surfaces of an inorganic particulate are interacted with a water-soluble polyvalent metal salt in an aqueous medium. The treated particle surfaces have a significant cationic surfaces charge imparted to them. The salt is a salt of a metal of Group II or Group III of the Periodic Table. Inkjet recording media treated with a coating composition containing the above pigment provide high density, fast-drying, and non-feathering ink images with suitable water fastness, while the coating compositions also offer cost advantages and improved rheology at higher pigment levels over coatings based on silica pigments.

Description

PIGMENT AND METHODS FOR USE IN RECOVERY MEDIA FOR RECORDING MEDIA WITH INK JET BACKGROUND OF THE INVENTION Field of the Invention This invention relates to pigments for coating compositions for ink recording media, especially adapted for ink jet printing, and to methods for preparing and using the pigments and coating compositions.

Description of the Related Art Ink jet recording processes represent one of the most important and widely used technologies for high speed electronic printing.

Ink jet printers typically include a plurality of nozzles connected to a liquid base ink supply. The nozzles can be excited to spray ultrafine liquid droplets of the ink, when demanded. Typically, a series of the nozzles is controlled to emit the ink drops in the pattern of characters or images on a paper surface. Thermal bubble printers and. piezoelectric printers are the two primary, prevalent inkjet technologies currently used by printer manufacturers.

Conventionally, ink jet printers have used a water-based ink. Typical inks contain a smaller amount of ink pigment and a larger amount of water as a vehicle. The paper used in an inkjet printer determines to a large extent the quality of the printed image. Suitable papers for ink jet printing typically involve a base paper, coated with a composition that improves the paper ink receiving properties. The base paper for ink-receptive coatings is usually made of bleached chemical pulp, to which charges, dyes and, if necessary, hardening agents and strength enhancers have been added. The conventional ink-receiving coating composition applied to the base paper generally includes a binder and a fine, porous powder capable of absorbing the coated ink on a paper surface. Matte and high-gloss inkjet papers are currently available at a significant price, higher than uncoated papers. The properties of brilliance and absorption of paper greatly affect the quality of the image. Common, uncoated papers are generally not suitable for high-resolution ink jet printing. A rough or non-smooth paper dissipates light in more directions than a paper with a smoother surface. Smoother paper makes the images printed on it appear brighter, all other factors being equal. With regard to absorption, ideally, when the ink is sprayed onto the paper, it remains in a compact, symmetrical point. The ink should not be absorbed very deeply by the paper, because the sprayed point will lose optical density on the paper surface and will tend to "feathered". "Feathering" means that the sprayed ink spot is absorbed by the paper in a manner that spreads out laterally in an irregular manner to cover an area slightly larger than intended. As a result, the printed image looks somewhat blurred, especially at the edges. High-quality inkjet paper would ideally be pre-coated with a film that holds the ink near the surface of the paper, to give a printed image with increased optical density, while allowing the aqueous medium or vehicle to be absorbed additionally in the body of the paper to accelerate the setting and drying of the ink. This supports faster printing speeds and reduces the bleeding or ink transfer problems created by low vehicle absorbency. Therefore, improved print quality and accelerated ink drying times are desired. It is difficult to achieve the proper balance of those properties, especially at higher printer resolutions and with smaller dot diameters. Silicas are currently the coating pigment most widely used to make coated paper for inkjet. The structured silicas are synthetic products. In general, silicas create an acceptable balance of ink jet printing capacity and ink drying attributes. However, prior use of silicas for that purpose has drawbacks. Silicas are relatively expensive in their manufacture. In addition to the relatively high cost of silicas, the formation of grinding dust associated with silicas during coating must be treated as a material handling problem. Additionally, silicas have high surface areas, and coatings that contain them tend to develop viscosity very rapidly, with small increases in silica content. As a consequence, for application coatings on inkjet paper, which use silicas, the silica solids content is typically formulated at a relatively low value; while relatively large amounts of binder are required in order to obtain a sufficiently high agglutination resistance. Increased coating viscosities, found at lower pigment levels, associated with the use of silicas as an absorption pigment in paper coatings, make it difficult to handle coating weights at those low levels of solids. The high surface area of the silica is useful, since it creates an open structure in a continuous binder phase. This open structure allows rapid absorption of the ink, which leads to good ink drying properties in an inkjet printer.

U.S. Patent No. 4,478,910 discloses inkjet recording paper comprising a base sheet with a specific degree of sizing, having a coating layer comprising fine particles of silica and a polymeric water-soluble binder. U.S. Patent Nos. 6,140,406 and 6,129,785 describe a coating composition for an ink jet recording medium comprising an aqueous suspension of silica-absorbing pigment, a polyvinyl alcohol binder and a cationic fixing agent. Preferably the pigment is a mixture of 75 percent or more of silica gel having a pore volume of 0.5 to 2.0 cc / g and 10 percent or more of alumina or alumina trihydrate. US Patent 5,985,424 discloses a coated paper for ink jet printing, wherein a base coat having good absorbency for the ink vehicle and a top coat is an ink receiving coating. In a preferred embodiment, the base coat contains a mixture of precipitated calcium carbonate and calcined clay, dispersed in a common coating binder; while the topcoat includes smoked or pyrogenic silica, dispersed in an emulsion prepared from styrene, polymerized in the presence of polyvinylpyrrolidone (a non-standard binder). Other types of pigments have been proposed, in addition to silica, for coating compositions for paper. For example, conventional calcium carbonate powders, used as a coating pigment for paper, do not functionally improve the characteristics of the inkjet coated papers. Accordingly, conventional calcium carbonate can be beneficially added to paper coatings, to improve the optical effects, for example, to increase brightness and smoothness; but it typically adversely affects the printing capacity and drying properties of the ink. U.S. Patent No. 6,441,076 discloses the production of a coating composition for paper applicable to inkjet paper, wherein the composition contains a high level of solids, ultrafine particle sizes, carbonate calcium / polyvinyl alcohol of low molecular weight, fine particle size, dissolved, partially hydrolyzed. In this application, the surface area of the calcium carbonate is very high, in order to mimic the operation of a silica with a high surface area. However, color reproduction and drying of the ink are not consistent with a sheet coated with silica. U.S. Patent No. 5,397,619 describes an ink jet recording paper comprising a base paper having a recording layer on at least one of its surfaces, which contains at least 40 weight percent. of a pigment, and not more than 60 weight percent of binder; which has a surface roughness, at a height of ten points on the surface of the recording layer, of no more than 5 μm, and an air permeability not greater than 1,000 seconds. The pigment may be silica, white carbon or silica gel obtained by the wet method; Superfine silica, obtained by the dry method, or a complex of calcium carbonate and silica, having a particle structure consisting essentially of silica crystallized from calcium carbonate crystals. U.S. Patent No. 6,274,226 discloses mesoporous silicoaluminate pigments, which are formulated with polyvinyl alcohol as a binder, for use in paper coatings for inkjet paper and without carbon paper. U.S. Patent No. 5,997,625 discloses a coating pigment for ink-jet printing, comprising hydrous clay, a caustic clay, leached and calcined, and porous mineral. U.S. Patent No. 5No. 882,396 discloses a coating composition for paper, for preparing a coated paper for ink jet printing, which includes a mixed pigment selected from one or more of the following: kaolin, calcined kaolin, dolomite, ground natural calcium carbonate, precipitated calcium carbonate, calcium sulfate or talc, preferably comprising 1 to 50 weight percent coarse pigment and 99 to 50 weight percent fine pigment, certain prescribed particle size distributions, and a polymeric adhesive hydrophobe. U.S. Patent No. 4,554,181 discloses an ink jet recording sheet having a dual component cationic recording surface comprising a substrate having a recording surface containing a cationic polymer that is used in combination with a salt polyvalent metal, soluble in water, in which the polymer provides the surface cationic groups to interact ionically with an anionic dye to insolubilize it. Insofar as the coating compositions contain pigments, the '181 patent does not disclose any meaning connected with the order of mixing of that type of component with the other ingredients, and indicates a mixing method in a single container for formulating the compositions of coating. In addition, the '181 patent only discloses the use of non-anionic type binders in coating compositions. Most cationic polymers are slightly colored in their liquid form, varying from pale orange colors to intense orange-red colors. The colors inherited from the cationic polymeric ingredients used in the paper coating compositions can affect the final gloss and hue of the coated sheet. Additionally, the use of specific cationic pigments leads to differential reactivity with the colored ink jet components, which creates good retention of the ink, but may change the color tonality of the image being printed. It would be convenient to provide coating compositions using reduced levels of cationic polymers, which also meet the performance requirements. There is a need for less expensive pigment alternatives for synthetic silicas, in paper coating applications, especially inkjet paper, which provide convenient coating rheology for high solids applications, along with uniform printability, including , but without limitation to them, the reproduction of color, the density of the printing and the drying of the ink. It would also be desirable that these coating pigments could function with coating binders for ordinary paper, and that they could be applied in a modern high speed papermaking machine.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a pigment suitable for use in coating compositions of an ink recording medium, comprising an inorganic particulate material, having treated surfaces, obtained by the contact made between the surfaces of the inorganic particles with a polyvalent metal salt soluble in water, in an aqueous medium; wherein the treated surfaces have a surface cationic charge and the salt is a salt of a metal of group II or group III of the Periodic Table. Papers coated with treatments containing the pigments provide rapid absorption of the ink vehicle, fixation of the dye on the surface and strong surface properties, attributed to the low demand of the coating binder. The ink jet recording media, treated with a coating composition containing the above pigment, provides high density, fast drying and ink images that do not "feather", with increased resistance to water. The pigments of this invention are effective functional replacements for relatively more expensive siliceous pigments, and can be applied at high levels of solids in a standard papermaking machine. In one embodiment, the coating compositions of this invention may contain about 45 percent to 70 percent by weight; and more particularly about 50 percent to 65 percent by weight, of the surface-treated pigment, and are still processable and work well. In one embodiment of this invention, coating compositions are prepared by a method in which the inorganic pigments are pretreated separately with a polyvalent metal salt of group II or group III of the Periodic Table, before placing contacting the pigment with an effective cationic polymer, effective for the water-soluble polyvalent metal salt to make contact with the surfaces of the particulate inorganic material, to provide an inorganic particulate material with a treated surface, having a cationic surface charge in the surfaces put in contact; and then, in a subsequent process, the pigment with treated surface is combined with a cationic polymer in a coating composition. It has been found that this method allows solid levels of up to 60 percent or more by weight, to allow coating compositions without experiencing gelling problems. Preferably the cationic polymer comprises a quaternary amine compound and, more preferably, an epichlorohydrin-polyamine compound. The term "gelling", for the purposes of the present, means that a high degree of coagulation of the pigment is experienced, so that the mixing operation can not be continued due to the rapid accumulation of high viscosity. In another embodiment, the pigments are mixed separately with a cationic polymer comprising a quaternary amine compound, before it is contacted with the mineral, and the surface is treated with a salt of a group II or group III metal. the Periodic Table, which has been found to allow solids levels up to 45 percent or more, by weight, which are possible in coating compositions without experiencing gelling problems. If these mineral mixing sequences are not followed according to the embodiments of this invention, it has been observed that at least 45 percent solids can not be reached in the coating compositions, when the coating compositions are prepared using cationic polymers and pigments. In addition, the present invention allows to reduce the amount of cationic polymer otherwise required in the coating compositions. A more uniform coating appearance is also obtained using the coating formulations of the invention. further, the present invention allows to use reduced binder contents and common and ordinary types of binder, in inkjet coatings. The simplicity in the formulation and the reduced costs are due to the reduction in the surface area of the pigment used in the present invention. The low surface area pigment of the present invention achieves ink drying properties throughout the coating structure. In one embodiment, the proper interaction of the ink in an ink-jet recording medium is achieved by using a coating pigment according to one embodiment of this invention, wherein the pigment is derived from an inorganic particulate material, having a relatively low surface area, such as, for example, precipitated calcium carbonate (PCC) or ground calcium carbonate (GCC), having a specific surface area of less than about 15 m2 / g. This achieved capacity is unexpected in view of the tendency of the covering field in the inkjet paper, towards the use of calcium carbonates with high specific surface area (ie, more than 30 m2 / g in paper coatings. For the purposes of the present, the "specific surface area" is measured by the BET method, and when the CCP or CCG, which is alkaline material, is treated with the surface treatments with polyvalent metal salt, strongly acid, According to an embodiment of the invention, such as aluminum hydrochloride (ACH) (pH 4-5), surprisingly the ACH does not dissolve the calcium carbonate particles during the surface treatment process, in addition, the strongly cationic charge formed in the particle surfaces by treatment with ACH is retained even at strongly alkaline pH values, after surface treatment, without causing an indebted increase or in the content of Ca + 2, as an indicator of the dissolution of the particle. A paper coated with this pigment behaves as if the surface were cationic by nature. As a consequence, high density images can be printed on the coated paper, especially using an ink jet ink dye having anionic character. Also the use of AH results in the uniform absorption of all the dyes of the ink, which leads to a more faithful reproduction of the color. Additionally, the pigments of the present invention, cationically charged, can be surprisingly used with an anionic binder, in coating compositions for paper, without incurring high viscosity. As a result, common anionic latex pigments, such as those based on a styrene-butadiene rubber binder, a polyvinyl acetate binder, and others, can be used. Polyvinyl acetate and other anionic latexes are also attractive from the point of view of cost and convenience. As a result, the pigment solids content in the paper coating compositions can be increased up to 45 percent or more by weight, while the level of binder content is reduced concomitantly, which supports the use of the coating compositions in modern machines to make paper. The pigment with low specific surface area and low binder content of the coating compositions for paper produces increased hiding power, which manifests itself as a great whiteness of coating, which is considered to be attributable to the covering capacity achieved on the substrate. Print. Additionally, the pigments do not impart discolored colors nor do they have a bad odor or low viscosity of fluid in the form of an aqueous suspension. The pigments of the present invention can be used to increase the printability of a wide variety of printing substrates, such as sheets and rolls of coated and uncoated paper.; plastic fiber paper, plastic films, metallic paper, coated cardboard, uncoated cardboard, and others. The inkjet paper coatings for matte paper, in particular, using the non-siliceous pigments according to the present invention can be advantageously formulated. The pigments of the present invention may also be suitable for coating compositions for high luster papers. The above benefits and advantages are translated into a less expensive paper coating composition for ink jet paper. The present invention also relates to the coating formulation, since the coating formulation is quite unique in its use of anionic latex binders, as well as the low levels of these binders in an ink jet coating.

BRIEF DESCRIPTION OF THE DIAMETERS Figure 1 is a flow diagram of a process scheme for forming and using a pigment and a paper coating, according to one embodiment of the present invention. Figure 2 is a flowchart of a process scheme for preparing a paper coating, according to a particular embodiment of the invention. Figure 3 is a flow diagram of a process scheme for forming a paper coating, according to an alternative embodiment of the invention. Figure 4 is a graph illustrating various mixtures of fine and structured clay, and their impact on the printing ink densities and the drying speed of the ink, as described in an example hereof. Figure 5 is a graph depicting the particle size distribution of an ultrafine milled calcium carbonate (UFGCC), as described in an example hereof.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES In accordance with the brief description of the invention which is given above, the present invention is directed to a singular, surface-treated pigment useful for coating compositions for paper. The treated surface pigment has a cationic surface charge that will effectively attract anionic ink inks and the like. Among other aspects, the papers treated with coatings containing pigments with treated surface, described herein, satisfy the commercial demands of good quality, water resistance and high speed printing capacity in paper or other printing substrates coated with the compositions based on the pigments with treated surface described here. The treated surface pigments described herein also provide a low cost alternative to silica pigments, and the paper coatings containing them have lower binder demand and improved rheology. Additionally, the present invention includes techniques for preparing coating compositions that include pigments with treated surface and cationic polymers that enable the increase in solids levels. In this way, the invention makes it possible to obtain papers and other substrates for inkjet with a coating of lower cost, with a high solids content but extremely effective, suitable for digital printing. With reference to Figure 1, an illustrative, non-restrictive process scheme 100 is designated to form a pigment with treated surface, having a significant cationic surface charge, and the uses of that pigment in other intermediate and final products. The particulate inorganic starting material is a bleaching agent in the form of a solid powder. In a preferred embodiment, the particulate inorganic material comprises calcium carbonate (CaCO3) particles. The particulate calcium carbonate is supplied either as a natural calcium carbonate material, mechanically treated, or as a chemically synthesized reaction product. The calcium carbonate particles can be ground natural calcium carbonate (GCC), as indicated in step 101. Marble, limestone, gypsum and coral are natural source materials for calcium carbonate. These natural sources of calcium carbonate are subject to mechanical treatments including grinding to provide a particulate form of the material, such as ultrafine ground calcium carbonate (UFGCC). Typically, milling is performed without dispersant or, alternatively, a fugitive dispersant can be used for milling. Alternatively, the calcium carbonate particles can be supplied as a synthetic reaction product, in the form of precipitated calcium carbonate (PCC), as indicated in step 102. A wide variety of particle sizes and forms can be chemically produced. of calcium carbonate particle, through the processes of precipitation. Precipitated products of calcium carbonate have a more uniform particle size distribution, and a greater degree of chemical purity than commercially available GCC. However, the GCC can be less expensive. Calcium carbonate is commonly precipitated in the form of calcite, in which crystals typically have rhombohedral, cubic or scalenohedral forms; or in the form of aragonite, which is acicular. Vaterite is another precipitated form of calcium carbonate, known in the art, which is metastable. The precipitated calcium carbonate is usually manufactured in a reactor, carbonating a suspension of hydrated lime or "whitewash", which is produced by quenching quicklime (CaO), followed by dehydration / filtration of the reaction product and the grinding the product to a desired particle size and a desired particle distribution. Suitable techniques for precipitating calcium carbonate are generally known and applicable here. While not generally necessary for this application, the crude particles of calcium carbonate synthesized could also be screened or ground to a desired scale of size distribution, by processing techniques described, for example, in U.S. Pat. 6,143,065 and 6,402,824 (Freeman and coinventores); whose descriptions are incorporated herein by means of this reference. The untreated calcium carbonate particles can then be supplied to the surface treatment station of step 103 in the pre-existing form of aqueous suspension. Alternatively, the untreated calcium carbonate can be supplied for surface treatment in the form of dry powder, which is dispersed in an aqueous medium to form a suspension, as an initial surface treatment process. The untreated calcium carbonate particles, supplied for surface treatment, generally have an average particle size of about 0.1 μm to about 5.0 μm and, more particularly, between about 0.5 μm and about 2.0 μm. The particle size distribution, as defined by the slope (slope factor), is preferably less than about 1.8. The term "slope" means the quotient value of the diameter value with respect to which 75 percent of the particles are smaller (as a numerator), divided by the diameter value with respect to which 25 percent of the particles are smaller (as the denominator). ); where the particle sizes are measured by a Sedigraph particle size analyzer. Precipitated calcium carbonate (PCC) or ground calcium carbonate (GCC) usually have a specific surface area of less than about 15 m2 / g. The TAPPI brightness of the calcium carbonate particles is usually at least about 96, both before and after the surface treatment, as described herein. The starting material of inorganic white pigment, which is treatable on the surface according to the invention, is not limited to calcium carbonate. For example, it can also be aluminum trihydrate (ATH) and / or magnesium hydroxide (Mg (OH) 2) particles, and the like. However, calcium carbonate is especially preferred, since not only is it capable of being surface treated to impart cationic surface charge to the particles, as described herein, but calcium carbonate also increases the opacity, brilliance and resistance to yellowing and aging of the coated paper that uses it. The calcium carbonate particles fed by means of step 101 or 102 are then subjected to a surface treatment step, which imparts or increases the cationic charge on the surfaces of the calcium carbonate particles, to an advantageous level for printing applications. , as indicated in step 103. The calcium carbonate pigment is surface treated with a water-soluble, polyvalent metal salt of a Group II metal or group III of the Periodic Table, dispersed in an aqueous medium. common. In a preferred embodiment the polyvalent metal salt is aluminum chlorohydrate. For the purposes of the present the aluminum chlorohydrate is occasionally abbreviated "ACH0 The ACH has the chemical structure AI2 (OH) nCI6.n The ACH can be formed by reacting hydrated alumina with hydrochloric acid, according to the following general equation: 2AI (OH) 3 + nHCl? AI2 (OH) nCI6-n + nH20 where 1 <; n < 6. The relative activity of the ACH product can be defined as follows: (%) = n / 6 x 100. For the purposes of this invention, the reaction product that is used will preferably be the product of a reaction carried out for produce a product that has an activity of more than about 50 percent, or even 75 percent. For example, when "n" is 5, the chemical structure corresponds to: AI2 (OH) 5CI (CAS number 12042-91-0). The ACH can also be obtained commercially in the form of powder or in solution, such as from Reheis, Berkeley, NJ 07922, USA The ACH is added on the surface of the calcium carbonate particles in an effective amount to provide a level of increase in cationic surface charge that is correlated with observable / measurable increases in print density or ink-drying performance of inkjet documents coated with a coating composition containing the pigment treated on the surface . The level of addition necessary to achieve those improvements can be determined empirically by applying the teachings provided here. This level of ACH addition, in general, but not necessarily always, ranges from about 0.1 percent to about 5 percent, based on the dry weight of calcium carbonate. Preferably, the calcium carbonate is treated with the ACH before its introduction into the paper coating composition and the ACH can be added in wet or dry form. The increase in the cationic charge imparted to pigments with treated surface, by treatment with ACH, is directly measurable qualitatively and quantitatively, by the use of a charge titration analyzer, such as Mutek PCD02, a detection detector. charge of particles. This is also demonstrated by comparing the printing properties, such as print density, ink drying, and others, of the papers coated with the coating compositions containing the treated surface pigments, with comparisons using the untreated pigment. Further, when treating PCC or GCC, which is an alkaline material, with surface treatments with highly acidic polyvalent metal salt, according to one embodiment of the invention, such as aluminum hydrochloride (ACH) (pH 4-5). ), quite surprisingly the ACH does not dissolve the calcium carbonate particles during the surface treatment process. In addition, the strongly cationic charge formed on the particle surfaces, by treatment with ACH is retained even at high pH alkaline values, after the surface treatment, without causing an undue increase in the Ca + 2 content, as an indicator of the dissolution of the particle. A paper coated with this pigment behaves as if the surface were cationic by nature. As a consequence, high-density water-resistant images can be printed on the coated paper, especially using an inkjet ink, which has an anionic character, so that the pigment and ink surfaces have opposite ionic charges and, for ende, mutually attractive. The beneficial, non-destructive interaction provided and observed between the surface of the calcium particles and the strongly acidic ACH used to treat them according to this invention was unexpected. The calcium carbonate product with treated surface, obtained in step 103, is in the form of a suspension. It is an aqueous dispersion of calcium carbonate particles with treated surface, produced at approximately 30 percent solids. The suspension product of step 103, which contains the particulate material with treated surface may be devoid of water by a suspension drying technique, suitable to provide a dry powder form of the inorganic particulate material with treated surface, without reducing its effectiveness Dry powder can be used as a pigment source ingredient when formulating paper coating compositions, as indicated in step 1 04. The pigments can be dried to the powder form by spray drying or rapid evaporation drying techniques. Equipment and conditions useful for this general purpose include those known and generally applied to suspensions of particulate minerals. Alternatively, as indicated in step 109, the suspension resulting from the surface treatment of the pigment with the polyvalent metal salt, while dispersed in the aqueous medium in step 103, can be used directly as a pigment source ingredient when formulating the compositions for paper coating. This suspension can contain up to about 60 percent, or even 70 percent by weight, of solids composed of the pigments with treated surface, without encountering problems related to high viscosity. As another alternative, dry ACH, which can be obtained commercially, can be mixed with the dry pigment powder in a dry mixing operation. This dry mixture can be formed into a suspension and produces the same calcium carbonate material with active surface.

In step 105 the pigment is packaged as a dry powder, obtained through step 104, and packaged in any suitable and convenient manner. Alternatively, a suspension containing the treated surface pigment that is supplied directly from step 103 (step 109) can be packaged in a leak-proof liquid container and shipped and handled in this manner. In another alternative embodiment, the packing step 105 could be omitted entirely in scenarios in which the treated surface pigment is manufactured and used in a paper coating composition, in the same manufacturing facility or in a nearby facility. In this situation the product can be transported in bulk form, by means of a conveyor, a truck, a rail car (for dust) and the like, or through a pipeline (in suspension), between the different stations or sites of manufacturing. In step 106 a composition is formulated to coat paper with the pigment having the treated surface, in combination with a binder and other optional additives. In a preferred embodiment of this invention, as shown in the process scheme 200 of Figure 2, the coating compositions are prepared by a method in which the inorganic pigments are previously treated, separately, with a polyvalent salt of a metal of group II or group III of the Periodic Table, before the pigment is contacted with a cationic polymer, effective for the water-soluble polyvalent metal salt to make contact with the surfaces of the particulate inorganic material, provide an inorganic particulate material, with the treated surface, having a cationic surface charge on the contact surfaces, similar to step 103 of Figure 1. Subsequently the pigments are mixed with treated surface, with water in step 201, to provide a suspension, and then, in the subsequent processing step 202, which corresponds basically to step 106 of Figure 1, combines its of pigment with treated surface, with a cationic polymer when preparing a coating composition. The coating composition prepared in this way can be used in a paper coating process, such as in step 107 of FIG. 1. It has been found that this method allows pigment solids levels with treated surface, of up to 60%. one hundred or more in weight, which may be possible in coating compositions. The cationic polymer preferably comprises a cationic quaternary amine compound and, more preferably, is epichlorohydrin-polyamine. In one embodiment, the coating compositions of the present invention may contain from about 50 percent to about 70 weight percent of the pigment surface treated with ACH, and remain processable (e.g., do not gel and perform well). ). Diallyldimethylammonium chloride (DADMAC) can also be used as the cationic quaternary amine compound, in the practice of the present invention. Commercial examples of these cationic quaternary amine compounds include, for example: TRAMFLOC 864, from Tranfloc, Inc., Tempe, Arizona, E.U.A., and Nalkat 7607 from Ondeo; and PRP 2550. In another embodiment, illustrated in Figure 3, a process scheme 300 is used in which a mixture of water and cationic polymer comprising a quaternary amine compound is prepared in step 301, which is combined with pigments. that had not yet been treated on the surface, but with ACH at step 302, with perfect mixing to provide a uniform mixture. Subsequently, in step 303, the resulting aqueous mixture or suspension of cationic polymer and pigments is contacted, and treated on the surface with the salt of a metal of group II or group ill of the Periodic Table. It has been found that this alternative method allows solids levels of up to 45 percent or more by weight, which are possible in coating compositions. In one embodiment, a level of at least about 45 weight percent is sustainable in a coating composition prepared by this alternative technique of the invention. The cationic polymer used in this embodiment comprises the quaternary amine compounds described hereinabove. If these orders of mixing the ore according to the embodiments of this invention are not followed, it has been observed that coating compositions with a content of at least 45 percent pigment can not be obtained in the coating compositions prepared using cationic polymers and pigments. Therefore, this invention can incorporate the inclusion of cationic polymers and can also be implemented to reduce the total cost of the coating formulation, while maintaining the advantages observed when using an ion-exchange treatment. polyvalent metal. The cationic polymer requirements are reduced by the coating formulations, and can even be eliminated, by means of the present invention. The other additives may include the commonly used categories of additives for coating compositions intended to be used in inkjet paper, such as binder interlayers, prepping agents, dispersants, rheology modifiers, organic brighteners, starches, and others. . Illustrations of some of these aditives are provided here. It is important that the cationic pigments of the present invention, with an anionic binder in paper coating compositions, can be used without incurring high viscosity. Consequently, pigments with anionic latexes, such as those based on styrene-butadiene rubber binder, polyvinyl acetate binder, and others, can be used. Polyvinyl acetate and other anionic latexes are additionally attractive from a cost point of view. Since the coating viscosity does not unduly increase when higher levels of the treated surface pigment of the present invention are added, the solids content of the pigment in the paper coating compositions can be formulated to about 50 weight percent. , or even more, while concomitantly reducing the level of binder content, which supports the use of coating compositions in modern papermaking machines. Increased levels of suspended solids are made possible by the pigments with treated surface, which carry the cationic charge according to the present invention. In one aspect, a coating composition of the present invention includes, on a solids basis, pigments treated with ACH in an amount of about 25 to 70 weight percent; an anionic binder in an amount of about 2 to 15 weight percent, and a cationic polymer in an amount of 0 to about 15 weight percent. More particularly, a coating composition of the present invention includes, on a solids basis, pigments treated with ACH in an amount of about 45 to about 60 weight percent; an anionic binder in an amount of about 5 to about 12 percent, and a cationic polymer in an amount of about 5 to about 15 percent by weight. In step 107 the printing substrate is coated on at least one side or one side and typically on both sides, with the coating composition formulated in step 106. The coating can be applied to a printing substrate, using coating techniques suitable including conventional paper coating techniques. The coating composition can be applied to a low coating weight, using a size sizing press or other suitable means for apiication. In another embodiment of the invention, the surface treated pigment can be used alternatively, or additionally, as a paper filler, incorporated in the base paper. In step 108 an inkjet printer sprays ink in the form of an image onto the coated paper or other printing substrate. The coating weights are generally 2 grams per square meter (2 g / m2) for a specific quality of inkjet (in which the coating is normally applied at a low solids content) to more than 10 g / m2 in grades Higher quality inkjet. The coating weight is generally independent of the type of printing substrate on the sheet or roll form. The printing substrates to which the present invention can be applied are not necessarily limited, and include coated paper and standard uncoated paper, in discrete sheets or in rolls; plastic fiber paper (for example TYVEK sheets), plastic films (for example, plastic vinyl films), metallic paper (for example, aluminum foil), coated cardboard, uncoated cardboard, and others. The papers obtained from synthetic pulps and mixtures of synthetic pulp / wood pulp, which can be obtained commercially, are generally useful and, in particular, those which have uniform absorption characteristics. Coatings for inkjet paper, intended for matte paper, in particular, can be advantageously formulated to employ the pigments with non-siliceous surface treatment, described herein. The treated surface pigments of the present invention may also be suitable for coating compositions for some high luster papers, depending on the printing specifications. Aqueous ink jet inks and dyes, used in conjunction with paper coatings containing pigments with treated surface, according to the present invention, can be formulated in a conventional manner; it being understood that anionic inks are preferred, and inks may include additives, such as surfactants, solubilizing agents, humectants, etc. Papers coated with treatments containing the pigments provide rapid absorption of the ink vehicle and fixation of the ink dye on the surface. High density, uniform ink images are obtained that dry quickly and do not "plume", with increased resistance to water. The pigments of the present invention are effective functional replacements for the more expensive siliceous pigments when they are used in a coating with a low content of binder, with a high solids content. Additionally, the pigments of the present invention fix the dye-based inks, in a manner that increases the water resistance that, otherwise, it would be faced with untreated calcium carbonate, in inkjet coating applications. The pigment content of low specific surface area and the low binder content of the coating compositions for paper, produces increased concealing powder, which manifests as a high whiteness of the coating, considered attributable to the coating opacity achieved on the printing substrate. Additionally, the pigments with treated surface, according to the invention, do not impart faded colors to the printing substrates, while having little odor and low fluid viscosity in the form of an aqueous suspension. In comparison, when many mineral pigments are treated with commercial cationic polymers, such as cationic quaternary amine and epichlorohydrin polymers, their ink jet printing ability, color densities, water resistance and coating formation efficiency are increase However, most cationic polymers carry varying amounts of active component in the range of 30 to 50 percent, and their viscosities are different, depending on the molecular weight of the polymer used, which thus requires closed monitoring when formulating the composition of covering. Additionally, and as a serious drawback, most cationic polymers are slightly colored in their liquid form, ranging from pale orange colors to intense orange-red colors. The colors inherited from said cationic polymers can influence the final gloss of the coated sheet. Furthermore, the non-uniform absorption of the ink by the organic cationic polymers can result in problems with the reproduction of the color tonality in the coating. The present invention allows reductions in the amount of cationic polymer used, or reduces its undesirable effects. In contrast, such as to make high gloss matt coated inkjet paper, aluminum chlorohydrate and similar polyvalent metal salts are a superior surface treatment agent for calcium carbonate pigments, due, among other reasons , which remains in clear solution while interacting with the contact surfaces of the calcium carbonate particles, to form positive charges on them, and interacts with all dyes of the ink in a way that intimately reproduces the desired shade of color. Thus, the present invention provides a technique for modifying calcium carbonate particles to make them highly suitable for inkjet printing applications. EXAMPLES The following examples are presented to illustrate the invention, but it should not be considered that the invention is limited thereto. In the following examples, the parts are by weight, unless otherwise indicated. Experimental tests comparing the coating formulations used for inkjet printing paper, as applied in standard inkjet formulations, compared to the coating formulations of the present invention containing pigments with treated surface were carried out. , as described herein.

EXAMPLE 1 As control operations, an initial series of tests was carried out on several different kinds of pigments that had no surface treatments on them, with a polyvalent metal salt of a group II or group III metal. The coating formulations contained 100 parts of the pigment indicated in Table 1, together with 8 parts per hundred parts of a styrene-butadiene latex (ie, per 100 parts of pigment) The coating was applied to the base paper with a rod round wire and was applied to a coating weight of approximately 10 g / m2 Samples were produced from finished matte paper, coated in the laboratory, using each respective pigment, and then printed with an HP 820 inkjet printer Cse The printer settings were set at normal printing speed Table 1 below shows an effect of the respective pigment, observed on the print density (yellow: (Y), magenta (M), cyano (C) and black), ink drying, printing gloss and other properties.

TABLE 1 Pigment Density of print Density of the evaluation of the printed image AmaMaAzul Black ink Text BiseSangraBrillo Drying of coarse genta cocompuesta negative side of the balto print (Y + M + C) HG90 0.59 0.92 1.06 2.26 2.57 Poor No No Brilliant Slow CG 0.53 0.82 0.89 2.58 2.24 Bad Yes No Brighter Slow HC 0.52 0.80 0.87 2.18 2.19 Bad Yes No Slow Opaque CS40 0.51 0.83 0.91 2.19 2.25 Bad Yes No Semi- Slow brilliant CS80 0.45 079 0.86 2.18 2.10 Bad Yes No Opaque Very slow Niacol F 0.49 0.84 0.93 1.95 2.26 Good No No Matte OK 8044C 0.46 0.78 0.90 1.32 2.14 Good No No Opaque OK fifteen Pigment identifications: HG90: Hydragloss® is a high-gloss, high-gloss coating kaolin sold by J. M. Huber Corporation.

CG90: Covergloss® is a high brightness, high gloss, small particle size coating kaolin, sold by J. M. Huber Corporation. HC: Hydrocarb 90, is a carbonated calcium carbonate (GCC), quality coating, with fine particle size, sold by OMYA, Inc. CS40: Hubercarb® CS-40 is a PCC coating with fine particle size, produced by JM Huber Corporation. CS80: Hubercarb® CS-80 is a coating PCC, with coarse particle size, produced by J. M. Huber Corporation. Nyacol F: Colloidal silicate. 8044C: Ultrathin hydrous kaolin, with 99% particle size < 1 miera, produced by J. M. Huber Corporation. Property definitions: "Print density". It was determined by X-rite reflection densitometer. "Density of mixed ink". It was determined by the sum of the densities of the three colors (C.M.Y.). "Negative text". It was determined by shrinking the white text on a colored background. "beveled". It was determined by the fidelity of a line without artifacts, associated with the shift of the inks.

"Bleeding." It was determined by the fidelity of a black line on a yellow background. The shift is an indication of the drying speed. "Brightness". It was determined by the Hunter brightness meter, which measures the specular reflection of a surface. "Drying of the impression". It was determined by visual observation in a solid printing area. The results in Table 1 show that untreated mineral pigments give low densities of color printing. Fine particle coating pigments, such as HG90, Covergloss and CS40, exhibited good gloss effect on sheet and in print; but its ink drying speed was much lower than the other pigments. The slow speed of ink drying can cause fixing problems when stacked sheets are stacked in the delivery tray. The fixation problem can become a major problem when multiple print copies are produced, with a faster ink jet printer. Therefore, HG90, Covergloss and CS40 were considered unsuitable for manufacturing inkjet paper coated with matte finish. However, they can be a good selection of pigment for bright inkjet quality. Table 1 also shows that the untreated, spray dried clay GCC treated with Nyacol (DP-8044) and the calcined clay treated with Nyacol produce a matte finish coating having satisfactory ink drying speed. The ground calcium carbonate, untreated, was much brighter in color than the clay pigments. Figure 4 is a graph illustrating the inverse relationship between the color density of an inkjet print and the speed of ink drying using different mixtures of fine and calcined clays. A fine pigment provides better particle packing and creates a greater ink retention on the coating surface. The point to be decided is a gain in the densities of ink printing, but a slower speed of drying of the ink. This relationship also indicates that the optimization of the coating to obtain the best ink density and the best drying speed requires a careful balance of the pore structure of the coating.

EXAMPLE 2 Another series of experiments was carried out to compare the printing performance obtained using UFGCC pigments treated on the surface. Table 2 shows four different types of cationic materials that were used to treat on the surface four respective, different samples of ultrafine ground calcium carbonate (UFGCC) for which the color densities of the inkjet were measured and reported. The data shown here was based on a surface treatment using a 2 weight percent level of cationic agent in the surface treatment medium in which the GCC particles were dispersed. ACH was used to treat a sample of UFGCC, while the other three samples were treated with one of several types of polyquaternary amines, which were AGEFLOC B50LV, produced by Ciba Specialty Chemical Water Treatment Ltd .; 216LV, produced by Nalco; and CP-2. The UFGCC used was a commercial product, Hubercarb FG-1, produced by J. M. Huber Corporation. This material was produced by forming the GCC to a smaller size in a Cowles dissolver of 5 h.p. (Model W-14-2), formed by dispersion by Design, Inc. The sample was taken to a 38.1 cm (15") box, in which water was added, and then UFGCC was added in sufficient quantity to reach a 30 percent solids, then mix the mixture for 20 minutes at 3000 rpm, then slowly add 8 percent (as supplied) of the ACH ingredient to the mixture, while continuing to mix at a reduced rate ( about 1500 rpm.) Alternatively, one of the polyquaternary amines was added to this given example.The speed was increased again to 3000 rpm and the material was mixed for another 60 minutes, after which it was dried in a Niro spray dryer. Samples of paper with matte finish, coated in the laboratory, were produced using each of the various coating pigments of UFGCC with treated surface, using the method described in Example 1, and then printed with an impr HP inkjet printer model 820 Cse. The setting of the printer was set at normal printing speed.

TABLE 2 When comparing tables 1 and 2, it is noted that all cationically treated pigments show much higher densities of color ink, than untreated pigments. Cationic material is considered an essential ingredient for both coated and uncoated inkjet papers. Table 2 also shows that UFGCC treated with ACH produces slightly lower, but competitive and effective inkjet printing densities; but their advantage of significant cost and their loading efficiency makes them a preferable chemical to treat UFGCC coating pigments.

EXAMPLE 3 In another series of experiments, the effect of the dose of ACH cationic material on the printing color densities and the drying speed of the ink was investigated experimentally. The digital printing was carried out in a manner similar to that described in the previous examples, and the results of the color printing are summarized in the following table 3.

TABLE 3 Treatment with Color Density Printing ACH (%) Yellow Magenta Cobalt Blue Black Compound Colors (Y + M + C) 4 0.69 1.01 1.12 1.56 2.82 6 0.69 1.03 1.14 1.59 2.85 8 0.73 1.08 1.25 1.65 3.06 12 0.81 1.13 1.28 1.62 3.22 16 0.89 1.20 1.29 1.63 3.39 As seen from the results in Table 3, when the amount of ACH in the pigment is increased, the print color densities of the coated paper are also increased proportionally. The high print color density is one of the key parameters in the quality of printing with inkjet, in addition to the resolution of the printing, the beveling of the ink, the bleeding color to color and the drying speed of the ink. The ACH dose can be empirically optimized to obtain the best total print quality with inkjet, and can be combined with other polymers to reduce costs.

EXAMPLE 4 A further series of experiments was carried out to examine the preparation of various coating formulation compositions, which included UFGCC coating pigment treated with ACH, and then performance tests were carried out on printing, using various of these compositions. coating, against a matt, coated ink jet paper, commercially available. The UFGCC from Fairmount, Georgia, E.U.A., was obtained as an ultrafine milled calcium carbonate (UFGCC), not dispersed and dried. The average particle size of this pigment was approximately 1.5 microns. Figure 5 shows the particle size distribution of the UFGCC, after surface treatment with ACH, as described in this example, when measured by the Malvern particle size meter. The process for forming this treated product began with the formation of a suspension in water. The untreated UFGCC was mixed with water in a mixing tank, with moderate agitation, and using cooling vanes to obtain a solid with 30 percent pigments. Aluminum hydrochloride (50 percent active ingredient) was then added gently to the mixed suspension. Mixing was continued although the addition of the ACH to the water / pigment suspension may cause minimal initial flocculation of pigment. However, these soft flocs decompose rather quickly during mixing. Laboratory attempts were made to increase the solids of the UFGCC / water suspension, but gelation occurred, i.e., a higher degree of pigment coagulation was experienced, and the mixing operation could not be continued due to the high viscosity accumulation. . This attempt also explained that a pigment suspension of UFGCC treated with ACH, with a high solids content, could not be obtained simply by adding ACH to an untreated suspension of UFGCC / water, with a high solids content. Alternatively, it was found that ACH could be added to the liquid to which the dry pigment is added. As another alternative method, cationic polymer can be used to first disperse the pigment, after which the ACH can be added successfully as well. The cationic polymer was an epichlorohydrin-polyamine. Polymers of DADMAC or other quaternary polyamines could also be used. The treated UFGCC pigment suspension was dried in a spray dryer to form a dry powder. It could also have been dried by rapid evaporation in a drying equipment by rapid evaporation. The color of the ink jet coating was prepared as follows: The UGFCC treated with ACH was stripped to a suspension with 60 percent solids, to form the coating color. To form an inkjet coating color, other coating ingredients were added to the suspension, such as a binder, a viscosity modifier, an optical brightening agent and an interlayer. Extraordinary care is necessary when designing a coating color, since said positively charged pigment, such as UFGCC treated, can be neutralized with negatively charged ingredients, such as binders, insolubilizers and OBA. It can be observed, from a sieving in the laboratory when diluted ACH solutions are mixed with each of the coating ingredients, that the coating starches, such as PG290 and the polyvinyl alcohol binders are compatible. Most styrene-butadiene latexes are slightly incompatible; But other types of latex, such as vinyl acetate and vinyl acrylate, are incompatible. The interleaver, such as AZC, is not compatible with ACH and will cause severe coating precipitation. Incompatible coating ingredients should not be used in a coating formulation, since flocculation will occur and form granular aggregates. Occasionally a rapid viscosity balance has been observed, which makes mixing impossible. The SB latex should be added immediately after the starch, so that a sudden accumulation of viscosity can be avoided. The following coating compositions 1, 2 and 3 are examples of different coating formulations using surface-treated pigments according to this invention, which were used to coat matte-finish inkjet papers. Coating composition 1: Formulation of coating for ink jet, with matt coating. UFGCC treated with 8 percent ACH 100 parts Cationic polymer (PRP2550) 16.8 parts ACH303 (sol: -50% ACH solids) 13 parts Interlacer (Cartabond TSI) 1-2 parts alkyl ketene dimer (AKD) (Raisofob8105) 1 part Styrene-butadiene latex (SB) (Dow 383NA) 6 parts Polyvinyl alcohol (PVA) (Airvol 205) 6 parts TOTAL -144 parts Note: 1 part = 1 dry gram of dry material used.ACH303 is the commercial product Summit ACH-303. The pigment suspension and the following ingredients had the following solids contents in their respective dispersed forms, as used in coating composition 1: Pigment suspension, 60 percent; cationic polymer solids, 50 percent; ACH303, 50 percent solids; Cartabond TSI, 45 percent solids; AKD (cationic sizing agent), 50 percent solids; latex SB 50 percent solids; PVA 20 percent solids.

Coating composition 2: Formulation of coating for ink jet, with matt coating. UFGCC treated with 8 percent ACH 100 parts Cationic polymer (PRP2550) 16.8 parts ACH303 19.5 parts Interleaver (Cartabond TSI) 1-2 parts AKD (Raisofob8105) 1 part Polyvinyl acetate (Airflex7200) 12 parts PVA (Airvol205) 4 parts TOTAL -155 parts NOTE: 1 part = 1 dry gram of the material used. The pigment suspension and the following ingredients had the following solids contents in their respective dispersed forms, as used in coating composition 2: Pigment suspension, 60 percent; cationic polymer, 50 percent solids; ACH303, 50 percent solids; Cartabond TSI, 45 percent solids; AKD, 50 percent solids; PVAc (Airflex 7200), 72 percent solids; PVA, 20 percent solids.

Coating composition 3: Coated, matt inkjet coating formulation. UFGCC treated with ACH at 8 percent 100 parts Cationic polymer (PRP2550) 16.8 parts ACH303 19.5 parts Interlacer (Cartabond TSI) 1-2 parts AKD (Raisofob8105) 1 part Polyvinyl acetate (Airflex 1082) 15 parts TOTAL -154 parts Note: 1 part = 1 gram dry of the material used. The pigment suspension and the following ingredients had the following solids contents in their respective dispersed forms, as used in coating composition 3: Pigment suspension, 60 percent; cationic polymer, 50 percent solids; ACH303, 50 percent solids, Cartabond TSI, 45 percent solids, AKD, 50 percent solids; PVAc (Airflex 1082), 50 percent solids; PVA, 20 percent solids. For coating and finishing of paper, a high-gloss base sheet, which was squeezed lightly on the inside, should be used to form an ink-jet paper coated with a matte finish. A typical coating weight of between 16 and 20 grams per square meter per side is recommended, depending on the smoothness of the base paper. A smoother base sheet requires less coating to obtain full coverage; while a rough sheet needs more coating. This coating color can be formed to suit different types of coating blades, air knives or rollers, etc. A slight calendering of the coated sheet can be used to increase the final smoothness of the sheet; but excessive calendering is not recommended at all, as it will lower the drying speed of the ink, and may cause discoloration or color bleeding. Laboratory tests were performed on laboratory coated paper samples, a HP 820 Cse color inkjet printer, and an Epson Stylus 1270 printer. Printing mode was set at normal print speed, print quality normal and paper for photography. If applied, the coatings were applied to the base paper with a round wire roller and applied to a coating weight of approximately 10 g / m2. Table 4 shows the results of the ink jet test for a commercial quality (C1) inkjet sheet, coated with a matte finish, using silica pigment, obtained from a commercial office supplier . Table 4 also shows the results for a coated paper 1 ("1" which used UFGCC coating pigment treated with ACH, which represented invention. The base paper used in the coated paper 1 was a regular copy paper (i.e., 24 lb. paper, produced by Weyerhaeuser Corporation) and the coating composition used was the coating composition 1 described above. . The procedure used for the surface treatment of the UFGCC and the coating protocol were the same as those described in example 3 above. In the following tables in the examples, the paper type listing only means samples that were not coated with a composition described in these examples; while the mention of a coating composition means a sample in which it was applied to. paper for standard copy the aforementioned coating composition (at 60-80 grams per square meter, which was not treated with any surface treatment before being applied to the experimental coating.

The results of Table 4 show that the matte paper coated with a coating composition containing Surface treated UFGCC with ACH exhibited effective color printing and competitive performance compared to commercial coated paper, which uses relatively expensive silica pigment, and coated at low solids content. The quality of the printing could be significantly influenced by the design of the ink jet printer.

The differences in the printers include the types of ink, the speed of the printer, the algorithm increaser of formation of magen, and the sizes of the drops. The Epson stylus 1270 printer appeared to be a faster color ink jet printer, and its print head moved in both directions.

The faster speed of the printer makes the drying speed of the ink more demanding.

EXAMPLE 5 In another series of experiments, the protocol described in Example 4 was repeated, and then the digital printing was carried out in a manner similar to that described in the previous examples, except that color printing was carried out here, on paper for Epson inkjet, photo quality, on HP BrightWhite and Epson Premium Bright White papers, as commercial papers, and printing was performed on an HP Deskjet 1220C printer and an Epson Stylus Photo 1270 printer. Copy paper The standard was coated on separate samples with one of each of the coating compositions 1, 2 and 3, to determine the effects of the coating compositions on the properties of the print. The results of the color printing are summarized in the following table 5.

TABLE 5 fifteen EXAMPLE 6 In another series of experiments, the protocol described in Example 4 was repeated, and then digital printing was carried out in a manner similar to that described in the previous examples; except that the coating was used at around 2 g / m2, and color printing was carried out here, on HP-quality Brightwhite inkjet paper, on Epson Bright White Premium paper and on paper free wooden base, uncoated ("copy paper"), such as substrate papers, and with printing on a HP950C Deskjet printer and a HP1220C Deskjet printer. The results of the color printing are summarized in the following table 6.

TAB LA 6 Displays HP 950C Deskjet HP 1220C Deskjet Black Blue Magenta Yellow ComBgro Blue Magenta Yellow Comcobalto post cobalt HP White 1.51 1.17 1.19 0.19 0.88 0.34 1.60 1.10 1.11 0.83 3.04 bright Espson 1.29 1.28 1.27 0.92 3.47 1.52 1.25 1.23 0.85 3.33 Premium glossy 10 Paper for 1.10 1.10 1.13 0.86 3.09 1.49 1.08 1.09 0.79 2.96 copies Coating 1.53 1.26 1.27 0.91 3.44 1.54 1.22 1.22 0.89 3.33 5 Coating 1.55 1.30 1.25 0.96 3.51 1.58 1.25 1.23 0.90 3.38 Coating Formulation 4 Component Parts UFGCC treated with 8% ACH 100 TRAMFLOC F864 (8 quaternary amine Cartabond TSI (50% solids) 3 Airvol 203 (PVA) 7.2 F ormulation Coating 5: Component Parts UFGCC treated with 17% ACH 100 TRAMFLOC F864 (Amine 6.8 Quaternary Cartabond TSI (50% solids) 1.9 Airvol 203 6.1 EXAMPLE 7 In another series of experiments, three separate pigment compositions were prepared, according to different addition schemes, to investigate the effect of the synchronization of the addition of the cationic polymer, and the surface treatment of the pigments, on the viscosity and the thixotropic properties of the pigment compositions. In this regard, the following different preparation procedures were carried out. Process 1 generally followed the process scheme indicated in Figure 2, in which the surface of the pigment (UFGCC) was treated with a polyvalent metal salt (ACH), before combining it with the cationic polymer (TRAMFLOC 864). Process 2 generally followed the process scheme indicated in Figure 3, in which the untreated pigment was mixed with a cationic polymer, before the treatment of the pigments with ACH. In the comparative process A, ACH and the cationic polymer were added and simultaneously mixed with a pigment suspension. The rate of addition of the cationic polymer to the pigment, in these processes, was 55 cc / min / 500 grams of pigment. For these procedures the surface of the UFGCC pigment was treated with 8 percent ACH in the same manner as described in Example 4 above. No other ingredients were included in these compositions. The viscosity results, measured at two different speeds, the values of the percentage of solids at which gelation would occur in the various previous compositions, so that the viscosity could be measured, are indicated in table 7.

As illustrated by the above examples, the method for forming ultrafine milled calcium carbonate, treated with aluminum chlorohydrate, was successfully implemented experimentally. The process for treating UFGCC in accordance with this invention is easy, since it only requires a simple high shear mixer, with the option of drying the material for sale. This use of a particular GCC material, coupled with the polyvalent metal ion treatment and in combination with a low binder content coating with high solids content, is extremely crucial to obtain high solids content of coating, and increases the properties key printing, such as the densities of the printing ink, the resolution of the print and the water resistance. It was demonstrated that the UFGCC treated with aluminum chlorohydrate is an effective coating pigment to replace the silica pigment. It also decreases the production of dust that occurs in the use of silica, and allows to avoid a complex coating application process. The UFGCC treated with "ACH also increases the final content of color solids of the coating to 45 weight percent or more, and even to 50 weight percent or more, therefore, causes other coating processes, such as the spatula coating, the jet coating and the like, are viable to produce matte qualities of paper and the like It should be understood that various changes in the details, in the materials and in the arrangement of the parts are possible, as described above. and illustrated herein, in order to explain the nature of the invention, and said changes may be made by those having experience in the art, without departing from the principles or scope of the present invention, as expressed in the claims that come next.

Claims (25)

1. - A pigment suitable for use in coating compositions for an ink recording medium, characterized in that it comprises an inorganic particulate material, having treated surfaces, obtained by contact made between surfaces of the inorganic particulate material with a polyvalent metal salt, soluble in water, in an aqueous medium; wherein the treated surfaces have a cationic surface charge, and the salt is a salt of a metal of group II or group III of the Periodic Table.

2. The pigment according to claim 1, further characterized in that the particulate inorganic material is selected from the group consisting of calcium carbonate, aluminum trihydrate and magnesium hydroxide, kaolin, individually or a combination thereof.

3. The pigment according to claim 1, further characterized in that the particulate inorganic material comprises ground calcium carbonate (GCC).

4. The pigment according to claim 1, further characterized in that the particulate inorganic material comprises precipitated calcium carbonate (PCC).

5. The pigment according to claim 1, further characterized in that the particulate inorganic material comprises calcium carbonate particles having a surface area of less than 15 m2 / g.

6. The pigment according to claim 1, further characterized in that the water-soluble polyvalent metal salt comprises aluminum chlorohydrate.

7. The pigment according to claim 1, further characterized in that the particulate inorganic material having treated surfaces is in the form of dry powder.

8. A method for forming a pigment composition for ink recording media, characterized in that it comprises: i) mixing a particulate inorganic material and a water soluble polyvalent metal salt effectively to make the metal salt water-soluble polyvalent makes contact with the surfaces of the particulate inorganic material, to provide a particulate inorganic material with the treated surface, which has a cationic surface charge on the surfaces brought into contact; wherein the salt is a salt of a metal of group II or group III of the Periodic Table; ii) mixing, in an aqueous composition, the particulate inorganic material, which has the treated surface, and a cationic polymer comprising a quaternary amine compound.

9. The method according to claim 8, further characterized in that the mixing comprises mixing an aqueous suspension of the particulate inorganic material, and the water-soluble polyvalent metal salt.

10. The method according to claim 8, further characterized in that the mixing comprises dry mixing the particulate inorganic material and the particles comprising the water soluble polyvalent metal salt.

11. A method for forming a pigment composition for ink recording media, characterized in that it comprises: a) providing a first suspension containing an inorganic particulate material dispersed in an aqueous medium; b) adding water-soluble polyvalent metal salt to the first suspension, with mixing, in an amount and manner effective to provide a second suspension; wherein the water-soluble polyvalent metal salt is contacted with the surfaces of the particulate inorganic material to provide a surface treated inorganic particulate material having a surface cationic charge on the surfaces brought into contact; wherein the salt is a salt of a metal of group II or of group III of the Periodic Table; c) mixing the second suspension containing the inorganic particulate material having the treated surface, and a cationic polymer comprising a quaternary amine compound, in an aqueous medium, to provide a pigment composition.

12. The method according to claim 11, further characterized in that the pigment compositions contain from about 45 percent to about 70 weight percent of the particulate inorganic material, which have the treated surface.

13. The method according to claim 11, further characterized in that the cationic polymer comprises an epichlorohydrin-polyamine.

14. The method according to claim 11, further characterized in that the particulate inorganic material is added to the first suspension in an amount of from about 1 percent to about 30 percent by weight.

15. The method according to claim 11, further characterized in that the particulate inorganic material is added to the first suspension in an amount of from about 20 percent to about 30 percent by weight.

16. The method according to claim 11, further characterized in that the polyvalent metal salt is added to the second suspension in an amount of about 1 percent to about 30 percent by weight.

17. The method according to claim 11, further characterized in that the polyvalent metal salt is added to the second suspension in an amount of from about 3 percent to about 20 percent by weight.

18. The method according to claim 11, further characterized in that it additionally comprises drying the second suspension effectively to provide a powder comprising the particulate inorganic material having the treated surface.

19. The method according to claim 11, further characterized in that the inorganic particulate material provided in the first suspension is selected from the group consisting of ground natural calcium carbonate, precipitated calcium carbonate, aluminum trihydrate, kaolin and magnesium hydroxide , individually or a combination of them.

20. The method according to claim 11, further characterized in that the particulate inorganic material provided in the first suspension comprises calcium carbonate, and the polyvalent metal salt comprises aluminum chlorohydrate.

21. The method according to claim 11, further characterized in that the inorganic particulate material comprises calcium carbonate particles having a surface area of less than 15 m2 / g.

22. A method for forming a pigment composition for ink recording media, characterized in that it comprises: 1) mixing a particulate inorganic material and a cationic polymer comprising a quaternary amine compound, to provide a first suspension; 2) combining the first suspension with a water-soluble polyvalent metal salt, with effective mixing to provide a second suspension; wherein the water soluble polyvalent metal salt contacts the surfaces of the inorganic particulate material to provide an inorganic particulate material having a treated surface, having a surface cationic charge on the surfaces contacted; wherein the second suspension contains salt which is a salt of a metal of group II or of group III of the Periodic Table; wherein the second suspension contains at least about 45 weight percent of the surface treated with particulate inorganic material.

23. An aqueous coating composition for an ink jet recording medium, characterized in that it comprises an aqueous suspension of a particulate inorganic material and a binder; wherein the particulate inorganic material having treated surfaces, obtained by contact between the surfaces of the particulate inorganic material and a water soluble polyvalent metal salt, in an aqueous medium, prior to the introduction into the suspension of the particulate inorganic material; wherein the treated surfaces have a cationic surface charge, and the salt is a salt of a metal of group II or group Ili of the Periodic Table; and the binder comprises a material selected from an anionic binder or a non-binder Ionic

24. The coating composition according to claim 23, further characterized in that the inorganic particulate material comprises calcium carbonate, the polyvalent metal salt comprises aluminum chlorohydrate and the binder is selected from styrene-butadiene rubber, starch, polyvinyl acetate, acrylic polymer or polyvinyl alcohol, individually or in a combination of them.

25. The coating composition according to claim 23, further characterized in that the particulate inorganic material comprises calcium carbonate particles, having a surface area of less than 15 m2 / g, the polyvalent metal salt comprises hydrochloride of aluminum and the binder is selected from styrene-butadiene rubber, polyvinyl acetate, acrylic polymer, polyvinyl alcohol, individually or in a combination thereof. 25. The coating composition according to claim 23, further characterized in that the coating composition contains, on a solids basis, the inorganic particulate material having the treated surface, in an amount of about 45 to about 0.25. 70 percent by weight. 27. The coating composition according to claim 23, further characterized in that the binder comprises an anionic binder in an amount of from about 5 to about 12 weight percent of the composition; and a cationic polymer comprising a quaternary amine compound in an amount of about 5 percent to about 15 percent by weight, based on the solids. 28. A coating composition according to claim 23, further characterized in that it is applicable by spatula applicator, air knife applicator or other coating devices with high solids content. 29. A recording medium with ink, coated on at least one of its faces, with a coating composition as claimed in claim 23. 30.- A recording medium with ink according to claim 29, characterized also because the sheet of the recording medium comprises ink jet paper. 31. A recording medium with ink according to claim 29, further characterized in that the recording medium comprises ink jet paper with a matt finish.