RU2433050C2 - Sheet for printing with improved time of image drying - Google Patents

Abstract

FIELD: printing industry.

SUBSTANCE: invention relates to a sheet for printing with improved time of image drying, which contains the base including fibres of lignocellulose and water-soluble salt of bivalent metal. The value of Hercules sizing test ("HST") of the base and quantity of bivalent metal salt are selected so that the sheet for printing has a percentage of ink transfer ("IT%"), equal or less than approximately 60. At the same time the specified salt contacts with at least one surface of the base, and the salt of bivalent metal is salt of calcium.

EFFECT: proposed sheet for printing has improved time of image drying, as well as high sharpness of the edge in process of printing.

24 cl, 6 dwg, 10 tbl, 4 ex

Description

1. The technical field

The present invention relates to printing sheets. More specifically, the present invention relates to sheets for printing with improved drying time of the image and, in particular, to a sheet for printing on a paper basis, which is suitable for use as a sheet for any printing or recording method. Although the print sheet of the present invention is suitable for use in any printing method, it is particularly suitable for inkjet printing methods.

2. The level of technology

Known sheets for printing. See, for example, US Patent Nos. 6,207,258; 6123760; 6162328; 4,554,181; 4,381,185; 6,880,928; 6,207,258; 6123760; 6162328; 6,485,139; 6686054; 6761977; 6764726 and European Patents Nos. EP 0999937 and EP 0999937.

SUMMARY OF THE INVENTION

One aspect of the present invention is directed to a printing sheet containing a substrate that contains lignocellulose fibers and a water-soluble divalent metal salt, preferably on one surface of the substrate, the Hercules sizing test value (“HST”) of the substrate and the amount of divalent metal salt being selected so that the print sheet has a percentage of ink transfer ("IT%") equal to or less than 60. In preferred embodiments, the water-soluble divalent metal salt is in s Mesi, which also contains one or more starches, one or more polymer emulsion additives, one or more nitrogen-containing compounds, or a combination thereof.

The print sheets of the present invention have one or more advantages over traditional print sheets. For example, the printing sheets of the present invention have one or more properties of improved drying time of the image. These improved properties include reduced ink transfer immediately after printing, improved black density in the image, and improved edge sharpness when printing with pigment-based inks.

Another aspect of the present invention relates to a method for forming a sheet for printing of the present invention, which includes:

(a) applying a liquid composition containing a volatile liquid such as water, methanol and the like, with one or more divalent metal salts dissolved in it and one or more starches, one or more polymer emulsion additives, one or several nitrogen-containing compounds, or a combination thereof, on a surface of a base formed from lignocellulose fibers and having in contact with at least one surface thereof a water-soluble divalent metal salt, the value of t one hundred Hercules sizing ("HST") substrates and the amount of divalent metal salt are selected so that the print sheet has a percentage of ink transfer ("IT%") equal to or less than 60 to form a wetted and treated base having the aforementioned types or said mixture in contact with said surface; and

(b) drying said surface of said wetted and treated substrate to form said printing sheet.

Another aspect of the present invention relates to a method for creating images on a surface of a sheet for printing in a printing apparatus, the method including:

(a) introducing into said apparatus a print sheet containing a base that contains lignocellulose fibers and a water-soluble divalent metal salt, the Hercules sizing test value ("HST") of the base and the amount of divalent metal salt being selected so that the print sheet has the percentage of ink transfer ("IT%") equal to or less than 60, and

(b) forming an image on at least one surface of said print sheet. In preferred embodiments, the printing device is an inkjet printer, and an image is formed by expelling ink from said device to the surface of a printing sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and advantages of the invention will now be described together with the accompanying drawings, in which:

Figure 1 - graph of ink transfer (%) against the HST value of the base paper.

Figure 2 is a graph of ink transfer (%) against coating with salt - calcium chloride (g / cm).

Figure 3 is a graph of the density of black (OD _O ) against the HST value of the base paper.

Figure 4 is a graph of the density of black (OD _O ) against coating with salt - calcium chloride (g / cm).

5 is a graph of edge sharpness (EA) versus HST value of base paper.

6 is a graph of the sharpness of the edge (EA) against coating with salt - calcium chloride (g / cm).

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a printing sheet used for printing, which contains a base formed from lignocellulose fibers and having in contact with at least one surface thereof a water-soluble divalent metal salt. The authors unexpectedly found that the level of sizing of the substrate, as measured by the HST value of the substrate, and the amount of salts of divalent metals on the surface of the substrate affect the drying time of the image on the sheet for printing. The print sheet of the present invention has an improved drying time, which is determined by the amount of ink transferred from the print area to the empty area of the print sheet after rolling by a fixed mass roller. "Paint transfer" is defined as the amount of optical density transferred after rolling by a roller; it is expressed as a percentage of optical density transferred to an empty area of a sheet for printing after rolling by a roller. The method includes printing solid color blocks on paper, waiting for a fixed time, 5 seconds after printing, and then folding the sheet in half so that the print area touches the empty area of the print sheet, and rolling with a 4.5 lb manual roller, for example Roller No. HR-100 from Chem Instruments, Inc., Menton, Ohio, USA. The optical density was measured on the portable (OD _T ), non-portable (OD _O ) areas of the block and on the empty area (OD _B ) using a reflectance densitometer (X-Rite, Macbeth. Etc.). The percent transfer ("IT%") is defined as IT% = [(OD _T -OD _B ) / (OD _O - OD _B )] × 100.

The Hercules sizing test value ("HST") of the substrate and the amount of divalent metal salt are selected so that the print sheet has an ink transfer percentage ("IT%") of equal to or less than about 60. Preferably, IT% is from 0% to about 50% . More preferably, IT% is from 0% to about 40%. Most preferably, IT% is from 0% to about 30%.

In addition to improved image drying times, some of the printing sheets of the present invention preferably have good print quality. As used herein, the term “print quality” (PQ) is measured by two important parameters: print density and edge sharpness. Print density was measured using a reflectance densitometer (X-Rite, Macbeth. Etc.) in optical density units ("OD"). This method involves printing a solid color block on a sheet and measuring the optical density. There is some change in optical density depending on the printer used and the selected print mode, as well as the operating mode of the densitometer and color settings. In the method of the present invention, an HP DeskJet 6122 printer manufactured by Hewlett-Packard was used, using a No. 45 black cartridge (HP 51645A). The print mode was determined by the type of paper and the selected print quality. For the data of the present invention, a default value of uncoated paper and a fast-normal print quality mode were selected. An X-Rite 528 spectral densitometer with a 6 mm aperture was used. Values for density measurements were: Visual, T status, and absolute density mode. An improvement in print density is usually seen when sufficient water-soluble divalent metal salts are present on the surface of the paper. In general, the target optical density for black pigment ("OD _O ") is equal to or greater than 1.30 in standard (uncoated paper, normal) print mode for HP desktop inkjet printers that use the most common black ink (equivalent to ink in cartridge no. 45 for inkjet printing). Preferably, OD _O is equal to or greater than about 1.40. More preferably, OD _O is equal to or greater than approximately 1.50. Most preferably, the OD is equal to or greater than about 1.60.

Another setting for print sheets, which is important for determining good print quality, is edge sharpness ("EA"). Some print sheets of the present invention have good edge sharpness. Edge sharpness is measured with a device such as QEA's Personal Image Analysis System (Quality Engineering Associates, Burlington, Mass.), QEA ScannerIAS, or CameraX-based ImageXpert KDY. All of these devices receive an enlarged digital image of the sample and calculate the sharpness of the edge by image analysis. This value is also called edge distortion, and is defined in ISO 13660. This method involves printing a solid line 1.27 mm or more in length with a resolution of at least 600 dpi. The instrument calculates the location of the edge based on the dark color of each pixel near the edges of the line. The threshold value for the edge is defined as the point of 60% transition from the reflection coefficient of the base (bright region, R _max ) to the reflection coefficient of the image (dark region, R _max ) using the equation R ₆₀ = R _max -60% (R _max -R _min ) . After that, the edge distortion is defined as the standard deviation of the differences from the line selected to the threshold value of the line edge calculated perpendicular to the selected line. The edge sharpening value is preferably less than about 15, preferably EA is less than about 12. More preferably, EA is less than about 10. Most preferably, EA is less than about 8.

One important component of the printing sheet of the present invention is a base consisting of lignocellulose fibers. The type of fibers does not matter much and any such fibers known in the paper industry can be used. For example, the base can be made from fibers obtained from deciduous trees, conifers, or a combination of deciduous and coniferous trees prepared for use in a paper composition by any known method of cooking, dressing and bleaching, such as known mechanical, thermomechanical, chemical and semi-chemical methods and other methods of producing wood pulp. The term “hardwood” as used herein refers to pulps obtained from deciduous trees (angiosperms), such as birch, oak, beech, maple and eucalyptus, while the term “coniferous pulps” refers to pulps obtained from wood of cone-bearing trees (gymnosperms), such as various species of spruce and pine, for example, frankincense, Caribbean pine, spruce, balsam fir and Douglas fir. In some embodiments, at least a portion of the fibers can be obtained from non-woody herbaceous plants, including without limitation kenaf, hemp, jute, flax, sisal or abacus, although legal restrictions and other considerations may make the use of hemp and other fiber sources impractical or impossible . Bleached or unbleached pulp can be used in the method of the present invention. Recycled fiber is also suitable. In one preferred embodiment, the cellulosic fibers in the paper comprise from about 30% to about 100% by dry weight of coniferous fibers and from about 70% to about 0% by dry weight of hardwood fibers.

In addition to lignocellulose fibers, the base may also contain other conventional additives, such as, for example, fillers, retention aids, moisture resistant resins and dry strength resins, which can be incorporated into lignocellulose fiber based substrates. Among the fillers that can be used are inorganic and organic pigments, such as, for example, minerals such as calcium carbonate, barium sulfate, titanium dioxide, calcium silicates, mica, kaolin and talc, and polymer particles such as polystyrene latex and polymethyl methacrylate. Other conventional additives include, but are not limited to, alum, fillers, pigments, and colorants.

The paper base may also contain expanded or unexpanded microspheres dispersed in lignocellulose fibers. Expanded and expandable microspheres are well known in the art. For example, suitable expandable microspheres are described in co-pending applications with serial number 09 / 770,340 filed January 26, 2001 and serial number 10 / 121,301 filed April 11, 2002; U.S. Patent Nos. 3556934, 5514429, 5125996, 3533908, 3293114, 4483889 and 4133688; and in Great Britain Patent Application No. 2,307,487, the contents of which are incorporated herein by reference. In practicing the present invention, all conventional microspheres can be used. Suitable microspheres are synthetic resin particles having a generally spherical center containing liquid. Resin particles can be made of methimetacrylate, orthochlorostyrene, polyorthochlorostyrene, polyvinylbenzyl chloride, acrylonitrile, vinylidene chloride, para-tert-butyl styrene, vinyl acetate, butyl acrylate, styrene, methacrylic acid, vinyl benzyl chloride and more. Preferred resin particles comprise a polymer containing from about 65 to 90 wt.% Vinylidene chloride, preferably from about 65 to 75 wt.% Vinylidene chloride and from about 35 to 10 wt.% Acrylonitrile, preferably from about 25 to 35 wt.% Acrylonitrile. Suitable expandable microspheres are offered by Akzo Nobel, Marietta, Georgia, under the trade name EXPANCEL. Expandable microspheres and their use in paper materials are described in more detail in the jointly pending application with serial number 09 / 770,340, filed January 26, 2001 and the jointly pending application with serial number 10 / 121,301, filed April 11, 2002, the contents of which are included in this document by reference.

The value of the Hercules sizing test ("HST") of the substrate can vary widely and is selected to obtain the desired drying time characteristics. The HST value is measured according to the conditions set forth in the standard T-530 TAPPI method using 1% formic acid paint and an 80% reflectance endpoint. This test is usually used for alkaline paper containing a filler - calcium carbonate, as stated in an article by S.R.Boone, published in the journal TAPPI in February 1996, p.122. The HST value of the substrate can be adjusted by adding a sizing agent to the substrate. Preferably, the desired HST value is obtained by internal sizing of the base; that is, that the sizing agents are added to the cellulose suspension before it is converted into a paper web or base. Inner sizing helps to prevent swelling of the glued surface and turning into a sheet, allowing it to remain on the surface where it has maximum efficiency. Substances for internal sizing, which can be used to implement the present invention in practice, include any substances that are usually used in a wet section of a paper machine. These include rosin adhesives, ketene dimers and multimers, and alkenyl succinic anhydrides. Inner adhesives are typically used at concentrations known in the art, i.e. from about 0 wt.% to 1.0 wt.% by weight of the dry paper sheet. More preferably, the internal adhesive is used in a concentration of from about 0.01% to about 0.5% by weight. Most preferably, the internal adhesive is used in concentrations from about 0.025% to 0.25% by weight. The methods and materials used for internal sizing are discussed by E. Strazdins in The Sizing of Paper, Second Edition, ed. W.F. Reynolds, TAPPI Press, 1989, pp. 1-33. Suitable ketene dimers for internal sizing are disclosed in US Patent No. 4,279,794, which is incorporated herein by reference in its entirety, in UK Patent Nos. 7,865,403, 903416, 1373788 and 1533434 and published European Patent Application No. 0666368 A3. Ketene dimers are commercially available, for example in the form of Aquapel sizing agents. RTM and Precis. RTM from Hercules Incorporated, Wilmington, Delaware. Ketene multimers for use as internal adhesives are described in published European patent application No. 0629741A1, corresponding U.S. patent application serial number 08/254813, filed June 6, 1994, in published European patent application No. 0666368A3, corresponding to US patent application serial number 08 / 192570, filed February 7, 1994, and in US patent application serial number 08/601113, filed February 16, 1996. Alkenyl succinic anhydrides for internal sizing are disclosed in US Pat. No. 4,040,900, which is incorporated herein by reference in its entirety, and in the publication by C.I. Farley and RB Wasser (S.E. Parley / RBWasser) "Paper sizing (The Sizing of Paper), Second Edition, Edited by WFReynolds, TAPPI Press, 1989, pp. 51-62. Various alkenyl succinic anhydrides are available from Albemarle Corporation, Baton Rouge, Louisiana.

As is well known to one of ordinary skill in the art, the HST value will vary directly with the base mass of the substrate and other factors known to one of ordinary skill in the art, such as the amount and type of internal sizing agent, as well as the type, amount and surface area filler used with paint and reflectance end point according to TAPPI T 530. Based on the foregoing, one of ordinary skill in the art can use conventional e techniques and methods for calculating, determining and / or evaluating a specific HST value for the substrate used to provide the desired drying time characteristics of the image. In preferred embodiments of the present invention, the HST value is from about 1 second to 400 seconds when using 1% formic acid paint and 80% reflectivity. The HST value is more preferably from about 3 seconds to 300 seconds, and most preferably from about 5 seconds to 200 seconds. In better embodiments, the HST value is from about 20 seconds to 100 seconds.

The porosity of the Gurley base is chosen to provide the desired drying time characteristics. Gurley porosity is measured according to the TAPPI method T460 om-88. In preferred embodiments, the base has a Gurley porosity of from about 5 s / 100 ml to about 75 s / 100 ml. Gurley porosity is more preferably from about 5 s / 100 ml to 70 s / 100 ml and most preferably from about 5 s / 100 ml to 50 s / 100 ml. In better embodiments, the Gurley porosity is from about 10 s / 100 ml to 35 s / 100 ml.

The pore diameter of the base is chosen so as to provide the desired drying time characteristics. The pore diameter is measured with a mercury porosimeter. In preferred embodiments of the invention, the base has a pore diameter of from about 2.0 to 3.5. The pore diameter is more preferably from about 2.2 to 3.3, and most preferably from about 2.4 to 3.1. In better embodiments, the pore diameter is from about 2.6 to 3.0.

The base can have any base weight. Preferably, the base mass of the base is from about 20 to 500 g / m ² , although it may be beyond this range. The base weight is more preferably from about 20 to 300 g / m ² and most preferably from about 50 to 200 g / m ² . In better embodiments, the base weight is from about 60 to 120 g / m ² .

Suitable substrates obtained by conventional methods can be obtained from commercial sources, such as International Paper Company. Methods and devices for producing a base of lignocellulose fibers are well known in the field of paper and paperboard manufacturing. See, for example, Pulp and Paper Processor Handbook, ^2nd Edition, J.E. Smook, Angus Wilde Publications (1992) and the references therein. You can use any traditional method and device. Preferably, the method includes: a) preparing an aqueous suspension of lignocellulose fibers; b) forming the web and drying the suspension of lignocellulose fibers to obtain a dried paper web; c) drying the paper web to obtain a dried paper web; and d) calendaring the dried paper web. In addition to these steps, additional steps of the method known to one of ordinary skill in the art may be applied, such as, for example, the step of coating one or more surfaces of the web, where such a coating contains a binder with a dispersing pigment.

The base contains an “effective amount” of a water-soluble divalent metal salt, preferably in contact with at least one surface of the base. As used herein, the term “effective amount” means an amount that is sufficient to improve the drying time of the substrate by any amount. This total amount of a water-soluble divalent metal salt in the base can vary widely, provided that the desired result is achieved. Typically, this amount is at least 0.02 g / m ² , although smaller or larger amounts can be used. The amount of water-soluble divalent metal salt is preferably from about 0.1 g / m ² to 3 g / m ² and most preferably from about 0.2 g / m ² to 2.0 g / m ² . In better embodiments, the amount of water-soluble divalent metal salt is preferably from about 0.4 g / m ² to 1.5 g / m ² .

In the practice of the present invention, any divalent metal salt may be used. Suitable water soluble divalent metal salts include, but are not limited to, calcium or magnesium containing compounds. The corresponding ions can vary widely and include chloride, sulfate, nitrate, hydroxide, and the like. Examples of such compounds are calcium chloride, magnesium chloride and calcium hydroxide. Preferred water-soluble divalent metal salts for practicing the present invention are water-soluble calcium salts, especially calcium chloride.

In the most preferred embodiments of the present invention, the mixture comprising calcium chloride and one or more starches is in contact with at least one surface of the base. Examples of suitable starches for the implementation of this preferred embodiment of the invention are naturally occurring hydrocarbons synthesized in corn, tapioca, potato and other plants by polymerization of dextrose units. All such starches and their modified forms, such as starch acetates, starch ethers, starch ethers, starch phosphates, starch xanthates, anionic starches, cationic starches, oxidized starches and the like, which can be obtained by reacting starch with a suitable starch chemical or enzymatic reagent, can be used in the practice of the present invention. Suitable starches can be made by known methods or obtained from commercial sources. For example, suitable starches include Ethylex 2035 from A.E. Staley, PG-280 from Penford Products, oxidized corn starches from ADM, Cargill and Raisio, and enzyme-converted starches, such as Amylum Amyzet 150.

Preferred starches for use in the practice of the present invention are modified starches. More preferred starches are cationic modified, chemically modified starches, such as leaded starches, oxidized starches and starch grains converted by AP and an enzyme, most preferred are chemically modified starches, such as leaded starches, oxidized starches and starch grains converted by AP and enzyme.

When using the preferred water-soluble divalent metal salt, calcium chloride and the preferred Ethylex 2035 starch, the desired drying time of the sheet is achieved when the weight ratio of calcium chloride to starch is equal to or greater than about 5% -200%. In these embodiments, the weight ratio of calcium chloride to starch is preferably from about 5% to 100%, more preferably from about 7% to 70%, and most preferably from about 10% to 40%.

In these preferred embodiments, the amount of the mixture of the water-soluble divalent metal salt and one or more starches on the surface of the base can vary widely, and any known amount can be used. In general, the amount of the base mixture is at least about 0.02 g / m ² of print sheet, although more or less can be used. This amount is preferably at least about 0.05 g / m ² , more preferably at least about 1.0 g / m ^2, and most preferably from 1.0 g / m ² to 4.0 g / m ² .

In addition to the desired divalent metal salt, the mixture used to treat the base may contain other ingredients besides starch used in preferred embodiments of the invention, including pigment, typically applied to the surface of a sheet for printing in conventional amounts. Such additional components also include dispersants, surface sizing agents, optical brighteners, fluorescent dyes, surfactants, deforming agents, preservatives, pigments, binders, pH control agents, coating release agents and the like.

Other auxiliary components are nitrogen-containing compounds. Suitable nitrogen-containing organic compounds are compounds, oligomers and polymers that contain one or more quaternary ammonium functional groups. Such functional groups can vary widely and include substituted and unsubstituted amines, imines, amides, urethanes, quaternary ammonium groups, dicyandiamides, guanides, and the like. Examples of such materials are polyamines, polyethyleneimines, copolymers of diallyldimethylammonium chloride (DADMAC), copolymers of vinyl pyrrolidone (VP) with quaternized diethylaminoethyl methacrylate (DEAMEMA), polyamides, cationic polyurethane latex, cationic polyvinylamide diamide diamide diamide diamide diamide diamide ) ethylene (dimethyliminio) ethylene] dichlorides, guanidine polymers and polymer biguanides. These types of compounds are well known and described, for example, in US patent No. 4554181, 6485139, 6686054, 6761977 and 6764726.

Preferred nitrogen-containing compounds for use in practicing the present invention are low and medium molecular weight cationic polymers and oligomers having a molecular weight equal to or less than 100,000, preferably equal to or less than about 50,000 and more preferably from about 10,000 to 50,000. Examples of such compounds are copolymers polyalkylamine and dicyandiamide, poly [oxyethylene (dimethyliminioethylene (dimethyliminioethylene) dichlorides and polyamines having a molecular weight in More preferred nitrogen-containing organic compounds for use in the practice of the present invention are low molecular weight cationic polymers such as a copolymer of polyalkylamine and dicyandiamide, poly [hydroxyethylene (dimethylimino) ethylene (dimethylimino) ethylene] dichloride, guanidine polymers and polymeric bigigans. nitrogen-containing organic compounds for use in the practice of the present invention are low molecular weight Ecological copolymers a copolymer of polyalkylamine and dicyandiamide, guanidine polymers and polymer biguanides such as polyhexylene biguanide.

The printing sheet of the present invention can be made using known methods. For example, a substantial one or more water-soluble divalent metal salts, preferably mixed with one or more starches and one or more auxiliary components, can be dissolved or dispersed in an appropriate liquid medium, preferably water, and can be applied to the substrate by any known method, such as glue press processing, dip coating, reverse roll coating, extrusion coating, and the like. Such coating methods are well known in the art and will not be described here in detail.

For example, the coating may be applied in traditional size press equipment having a vertical, horizontal or inclined size press configuration used in the manufacture of paper, such as equipment such as Symsizer (Valmet), size press KRK press (Kumagai Riki Kogyo Co., Ltd. , Nerima, Tokyo, Japan) by immersion coating. The KRK size press is a laboratory size press that models a commercial size press. In this size press, a sheet feed is usually used, while in a commercial size press, a continuous web is usually used.

During immersion processing, the web of the material to be processed is transported below the surface of the liquid coating composition with one shaft so that the open side is impregnated, after which the excess of the processing mixture is removed by the pressure rolls and the web is dried at 100 ° C in an air dryer. A liquid treatment composition typically contains a treatment composition dissolved in a solvent such as water, methanol, etc. A method of processing the surface of a substrate using a coating device provides a continuous sheet of substrate with a processing material applied first to one side and then to the second side of the substrate. The substrate can also be processed by a slotted extrusion method in which the flat die is located in close proximity to the base fabric to be processed, creating a continuous film of the treatment solution uniformly distributed on one surface of the sheet, after which drying is carried out in an air dryer at a suitable temperature, for example, at 100 ° FROM.

The printing sheet of the present invention can be printed by creating images on the surface of the sheet using traditional printing methods and devices, such as laser, inkjet, offset and flexographic. In this method, the printing sheet is inserted into the printing apparatus, and an image is formed on the surface of the sheet. The printing sheet of the present invention is preferably printed by inkjet printing methods and devices, for example, a desktop inkjet printer and a high-speed professional printer. One preferred embodiment of the present invention is directed to an inkjet printing method, which comprises applying an aqueous printing liquid to a printing sheet of the present invention in an image-like form. Another embodiment of the present invention is directed to an inkjet printing method, which includes: (1) introducing into the inkjet printing apparatus comprising water-based ink a print sheet of the present invention and (2) allowing dropping ink droplets in an image-like form onto a sheet for printing, thereby creating images on a sheet for printing. Inkjet printing methods are well known and described, for example, in US Pat. image, thereby providing the ejection of droplets of paint in a form similar to the image. The sheets for printing of the present invention can also be used in any other method of printing or creating images, for example, printing in plotters, creating images in color laser printers or copiers, hand writing with pens, offset printing methods, etc. provided that the toner or ink used to form the image is compatible with the ink-receiving layer of the sheet for printing. The present invention will now be described with reference to the following examples. These examples are illustrative only, and the invention is not limited to the materials, conditions or parameters of the methods specified in the examples. All proportions and percentages are expressed in units of mass unless otherwise indicated.

Example 1

(A) Preparation of laboratory impregnating compositions

A series of coating compositions was prepared in the following order. The coating was prepared in the laboratory in a mixer with a small shearing force. Some water was added to the coated container, and then anhydrous calcium chloride (94-97%, mini pellets from Dow Chemical Co., Midland, Michigan, USA) was added under an appropriate shearing force until dissolved. Coating compositions and specifications are listed in table 1.

Table 1. Songs Composition Calcium Chloride Share Water share one 2.5 97.5 2 5 95 3 10 90

B. Preparation of processed bases

Several samples of a commercially available base paper with a base weight of approximately 75 g / m ² and HST values of approximately 20 seconds to 220 seconds were coated with the compositions of Table 1. The base sheets and their specifications are shown in Table 2.

Table 2. Base paper Base paper Trade name Sizing Level (HST, s) BUT Office Max MaxBrite twenty AT Xerox Premium Multipurpose 61 FROM Hewlett packard multipurpose 157 D Hewlett Packard Everday Ink Jet 218

To apply the coating composition, both ends of a 9 × 12-inch base paper sheet were attached with a tape to the support sheet, the coating composition was applied with a thin line above the paper base, the Meyer rod was uniformly drawn along the sheet. By controlling the solids content in the compositions and rod size, a capture mass of 0.25-1.0 g / m ² per side was achieved. Coated substrates and their specifications are shown in table 3.

Table 3 Treated basics Machined base Composition Base paper Salt coating, g / cm 1A one BUT 0.25 1B one AT 0.25 1C one FROM 0.25 1D one D 0.25 2A 2 BUT 0.5 2B 2 AT 0.5 2C 2 FROM 0.5 2D 2 D 0.5 3A 3 BUT 1,0 3B 3 AT 1,0 3C 3 FROM 1,0 4D 3 D 1,0

Example 2

A series of experiments was conducted to evaluate the suitability of the basics from table 3 for inkjet printing. The properties selected for evaluation were drying time, print density, and edge sharpness. For comparison purposes, the same properties were evaluated for base stocks A, B, C, and D. The following order of operations was used.

A. Drying Time ("IT%"):

During this assessment, images were created on paper samples using a Hewlett-Packard Deskjet 6122 printer manufactured by Hewlett-Packard with a black cartridge (HP part number 51645A) under TAPPI room conditions (23 ° C and 50% relative humidity). The print mode was determined by the type of paper and the selected print quality. We used the default printer settings - uncoated paper and fast, normal print quality. An X-Rite Model 528 spectrodensitometer with a 6 mm aperture was used. The settings for density measurements were as follows: color — visual, T status, and absolute density mode. 5 seconds after printing, the samples were folded in half and rolled with a 4.5 kg hand rubber roller, catalog number HR-100 from Chemlnstruments, Inc., Mentor, Ohio, USA. Samples were opened and allowed to air dry. The density of the samples was measured with an X-Rite 500 series densitometer to determine the density before (OD _O ) and after (OD _T ) rolling, the empty area was also measured to obtain the paper background value (OD _B ). Then, the percentage of ink transfer ("IT%") for various papers was calculated by the following equation:

IT% = [(OD _T -OD _B ) / (OD _O -OD _B )] × 100.

B. Print Density ("OD _O ")

In this assessment, images were created on paper samples using an Hewlett-Packard DeskJet 6122 inkjet printer from Hewlett-Packard, using a black cartridge (HP 51645A catalog number), in TAPPI room conditions (23 ° C and 50% relative humidity). The print mode was determined by the type of paper and the selected print quality. The default settings were selected - uncoated paper and fast, normal print quality. Samples were allowed to air dry. The print density was measured with an X-Rite Model 528 spectrodensitometer with a 6 mm aperture. The settings for density measurements were as follows: color — visual, T status, and absolute density mode.

C. Edge Sharpness (“EA”)

In this assessment, images were created on paper samples using an Hewlett-Packard DeskJet 6122 inkjet printer from Hewlett-Packard, using a black cartridge (HP 51645A catalog number), in TAPPI room conditions (23 ° C and 50% relative humidity). The print mode was determined by the type of paper and the selected print quality. The default settings were selected - uncoated paper and fast, normal print quality. Samples were allowed to air dry. The sharpness of the edge of the images on the samples was measured using a personal image analysis system from QEA (Quality Engineering Associates, Burlington, Massachusetts).

The results of these evaluations are shown in table 4 and figure 1-6.

Table 4 Machined base IT% OD _O EA HST (S) Salt coating, g / cm 1A four 1,62 13.8 twenty 0.25 1B twenty 1.68 8.7 61 0.25 1C 59 1,63 6.8 157 0.25 1D 58 1,63 6.3 218 0.25 2A 3 1,61 9.1 twenty 0.5 2B eighteen 1.65 8.1 61 0.5 2C 43 1,64 7.0 157 0.5 2D 71 1,62 5.9 218 0.5 3A four 1,61 8.5 twenty 1,0 3B 27 1,64 6.8 61 1,0 3C 49 1,62 6.4 157 1,0 3D 68 1,59 5.9 218 1,0

Base paper A one 1.06 29.7 twenty 0 Base paper B 46 1.31 18.6 61 0 Base paper C 76 1.43 23.8 157 0 Base paper D 87 1.51 6.3 218 0

Example 3

(A) Preparation of compositions for size press

A series of coating compositions was made according to the following procedure. The coating was prepared in the laboratory using a mixer with a low shear force. A certain amount of pre-cooked starch was added to the coated vessel, then water and then a water-soluble divalent metal salt were added with appropriate shearing actions. Then, 0.6 parts of styrene-based surface sizing agent was added to the coating. The required amount of particulate matter for this application is from 11 to 16%, depending on the sensitivity of the system to the viscosity of the coating or composition for the size press and the desired level of grip. Compositions and specifications of coatings are given in table 5.

Table 5 Compositions for size press Composition for size press Leaded starch, proportion Calcium Chloride Share Water share one eleven 0 89 2 eleven one 88 3 eleven 2 87 four 12 3 85 5 12 four 84

(B) Preparation of inkjet paper processed in a size press

1. Preparation of the basics

The basics used in this experiment were made on a paper machine from a fibrous composition consisting of 60% coniferous fibers and 40% eucalyptus fibers, and 15% precipitated calcium carbonate with an internal adhesive - alkenylate anhydride (ASA). The base weight was approximately 75 g / m ² and the HST value of the base paper was approximately 20 seconds.

2. Processing in a size press

The base paper used in this experiment had a base weight of approximately 75 g / m ² and an HST value of approximately 20 seconds. To apply the coating composition, a 12-inch-wide roll of paper base was continuously fed between the two shafts, and the coating composition was pumped into the contact zone reservoir, and paper was fed through the contact zone reservoir at a predetermined speed. By controlling the solids content of the composition and the speed of passage through the size press, a grip mass of about 2.2 to 3.0 g / m ^{2 was} obtained.

The foundations processed in the size press and their specifications are shown in table 6.

Table 6 The basis processed in the size press The basis processed in the size press Sizing composition Starch coating, g / cm Salt coating, g / cm one one 2.2 0 2 2 2.2 0.2 3 3 2.2 0.4 four four 2.2 0.6 5 5 2.2 0.8

Using the procedures of Example 2, it was determined the values of IT%, OD _O and EA for the bases processed in the size press, from table 6. The results of these evaluations are shown in table 7.

Table 7 The basis processed in the size press IT% OD _O EA HST, s Salt coating, g / cm one 70 1.24 9.1 57 0 2 42 1,56 7.7 47 0.2 3 28 1,57 8.1 47 0.4 four 31 1,60 7.4 58 0.6 5 thirty 1.51 6.9 47 0.8

Example 4

(A) Preparation of compositions for processing in a size press

A series of coating compositions was prepared by the following procedure. Coating ingredients, such as cooked starch, water-soluble divalent metal salt, water, various coating additives, such as optical brighteners, anti-foam additives, cationic polymers, adhesives and cross-linking agents, were continuously fed into the paper machine press tanks with stirring. The required particulate levels for this application ranged from 5 to 25%, depending on the sensitivity of the system to the coating or the viscosity of the size press composition. Compositions for size press and specifications are given in table 8.

Table 8 Compositions for size press Composition for size press Leaded starch, proportion Calcium Chloride Share Cationic polymer, fraction Water share one 8 0 0 92 2 8 2.5 0 89.5 3 6 2.5 3,5 88

(B) Preparation of inkjet paper processed in a size press

1. Preparation of the basics

The bases used in this experiment were made on a paper machine from a fibrous composition consisting of 60% fibers and 40% eucalyptus fibers and 15% precipitated calcium carbonate with an internal adhesive, alkenyl succinic anhydride (ASA). Base weight was approximately 75 g / m ² and the HST value of the base paper ranged from about 30 seconds to 150 seconds.

2. Car experiments

To apply a sizing composition, the ingredients were pumped into a stainless steel tank at a predetermined flow rate and dosed onto a paper base in a size press with a dosing rod or dipping. By controlling the solids content in the composition and the pressure in the contact zone, a capture mass of approximately 3.0 g / m ² was obtained.

The foundations processed in the size press and their specifications are given in table 9.

Table 9 The basis processed in the size press The basis processed in the size press Sizing composition Salt coating, g / cm one one 0 2 2 0.8 3 2 0.8 four 2 0.8 5 3 1,0

Using the procedures of Example 2, it was determined the values of IT%, OD _O and EA for the bases processed in the size press, from table 9. The results of these evaluations are shown in table 10.

Table 10 Coated Base IT% OD _O EA HST, s Salt coating, g / cm one 71 1.30 9.7 118 0 2 36 1,54 7.2 139 0.8 3 27 1,52 7.5 121 0.8 four eleven 1,53 8.8 48 0.8 5 17 1,58 7.0 24 1,0

In light of the above description, changes in the above examples are possible. Therefore, although the invention has been described with reference to certain preferred embodiments, it will be understood that other compositions may be devised, which nevertheless fall within the scope and essence of the invention defined in the appended claims. The foregoing description of various preferred embodiments of the present invention is for purposes of illustration only, and it is understood that various modifications and changes may be made to the invention without departing from the spirit or scope of the invention as defined in the claims.

Claims (24)

1. A print sheet containing a base including lignocellulose fibers and a water-soluble divalent metal salt, where the value of the Hercules sizing test ("HST") of the base and the amount of divalent metal salt are selected so that the print sheet has a percentage of ink transfer (" IT% ") equal to or less than about 60, said salt contacting at least one surface of said base, and said divalent metal salt being a calcium salt. 2. A sheet for printing according to claim 1, characterized in that said lignocellulose fibers are a mixture of hardwood and coniferous fibers. 3. A sheet for printing according to claim 1, characterized in that said paper base has a Gurley porosity of from about 5 s / 100 ml to 75 s / 100 ml. 4. The sheet for printing according to claim 1, characterized in that the said paper base has a pore diameter of from about 2.0 to 3.5. 5. A sheet for printing according to claim 1, characterized in that said HST value is from about 3 to 300 s. 6. A sheet for printing according to claim 5, characterized in that said HST value is from about 5 to 200 s. 7. A sheet for printing according to claim 5, characterized in that said HST value is from about 10 to 100 s. 8. The sheet for printing according to claim 1, having a percentage of ink transfer ("IT%") equal to or less than about 50. 9. A sheet for printing according to claim 8, characterized in that the percentage of ink transfer ("IT%") is equal to or less than about 40. 10. The sheet for printing according to claim 9, characterized in that the percentage of ink transfer ("IT%") is equal to or less than approximately 30. 11. The print sheet of claim 10, wherein the percentage of ink transfer ("IT%") is equal to or less than about 20. 12. The sheet for printing according to claim 1, having a sharpness of the edge of the image ("EA") is less than about 15. 13. The sheet for printing according to item 12, characterized in that the sharpness of the edge of the image ("EA") is less than approximately 12. 14. The sheet for printing according to item 13, wherein the sharpness of the edge of the image ("EA") is less than about 10. 15. The sheet for printing according to 14, characterized in that the sharpness of the edge of the image ("EA") is less than about 8. 16. The print sheet according to claim 1, characterized in that the water-soluble divalent metal salt is calcium chloride. 17. The print sheet according to claim 1, having an optical density of the black pigment ("OD _O ") equal to or greater than 1.30. 18. The sheet for printing according to 17, characterized in that the optical density of the black pigment ("OD _O ") is equal to or greater than 1.40. 19. The sheet for printing according to 17, characterized in that the optical density of the black pigment ("OD _O ") is equal to or greater than 1.50. 20. The sheet for printing according to 17, characterized in that the optical density of the black pigment ("OD _O ") is equal to or greater than 1.60. 21. The print sheet according to claim 1, having on the surface of the base a mixture of one or more water-soluble salts of divalent metals and at least one of one or more starches, one or more additives of polymer emulsions, one or more nitrogen-containing compounds or their combinations. 22. A method of forming a sheet for printing, which includes:
(a) applying a liquid composition containing a volatile liquid having a divalent metal salt dissolved in water or dispersed in it to a surface of a base containing lignocellulose fibers to form a wet treated base with said salts in contact with said surface, characterized in that the value of the Hercules sizing test ("HST") of the substrate and the amount of divalent metal salt are selected so that the print sheet has a percentage of ink transfer ("IT%") equal to or less than about 60, the removed salt is in contact with at least one surface of said base, and the water-soluble divalent metal salt is a calcium salt, and
(b) drying said surface of said wet treated substrate to form said printing sheet. 23. A method of creating images in a printing device, which includes:
(a) introducing into the said apparatus a printing sheet containing a base that contains lignocellulose fibers and a water-soluble divalent metal salt, in which the value of the Hercules sizing test ("HST") of the base and the amount of divalent metal salt are selected so that the printing sheet had a percentage of ink transfer ("IT%") equal to or less than about 60, said salt contacting at least one surface of said base, and the water-soluble divalent metal salt is a calcium salt; and
(b) forming an image on at least one surface of said print sheet. 24. The method according to item 23, wherein said printing device is an inkjet printer, and said image is formed by allowing ink to be pushed out of said device onto a surface of a printing sheet.

Images