FI122186B - Press Substrates - Google Patents

Description

Press Substrates

BACKGROUND OF THE ART

The present invention relates to a printing substrate containing wood fiber. It also relates to a printing process comprising said printing substrate.

BACKGROUND OF THE INVENTION

One of the most commonly used modern printing methods is offset printing, which is a printing method in which an intermediate rubber cylinder is used for transferring an image from an image surface (plate) to the substrate (usually paper). An offset printing unit comprises a platen cylinder, paint and wetting rollers, a rubber cylinder and a load roller. The printing plate comprises hydrophilic, water-absorbing parts and hydrophobic, color-absorbing parts. The water-absorbing portions of the plate form non-image surfaces, whereas the color-absorbing portions form image surfaces. The humidifying rollers apply chemically modified water, so-called moisture water, to the non-image surfaces of the plate, after which paint is applied to the image surfaces of the plate. The color and moisture water are transferred to the printing substrate from the printing plate via a rotating rubber cylinder coated with a smooth offset cloth.

In the heatset roll offset printing process, the substrate is continuously printed in one or more printing units and then dried in a hot air dryer to dry the ink printed on the substrate. Finally, the color is put on cooling rollers. The two sides of the movable web are simultaneously pressed into a pressure nip which is made up of an upper and a lower pressure rubber cylinders. In conventional four-color printing, light printing units are required, four on both sides of the web. Color from all printing units is transferred onto the substrate prior to drying. By this is meant that ink from the first printing unit is printed on a dry paper surface and that ink from the last printing unit is transferred onto a substrate which prior printing units have moistened with the water of moisture.

The ink mainly consists of color pigments, adhesives for attaching the pigment to the surface of the substrate and solvents for generating suitable flow properties. In the dryer, most of the color solvent evaporates rapidly in hot air. The color layer on the substrate surface achieves its final hardness in the cooling step of the cooling rollers. Then, the printed web is usually moved to a folding unit, where it is folded and cut into printed signatures.

Moisture water is required to separate the image surface and the non-image surface of the offset printing plate. However, the moisture water can cause serious problems after the ink has been transferred onto the printing substrate. Moisture water transferred to a coated coating substrate can reduce the strength of the coating layer. In multicolor heatset roll offset printing of coated substrate, the substrate is wetted in the first printing unit. In subsequent printing units, the color is transferred to an already moistened substrate surface. Since sticky paint is transferred onto a coating layer of reduced strength, napping of detached coating particles may occur. These particles tend to accumulate on the printing cloth in a cumulative manner and cause the need for cleaning of the fabrics.

It has previously been assumed that the printing substrate, e.g. a printing paper, should be highly porous and hydrophilic to absorb the moisture water transferred to the substrate. However, penetration of the moisture water into a porous, fibrous material can cause swelling of the wood containing fibers. Fiber swelling causes an increase in the dimensions of the paper, so that an image printed in the first pair of printing units does not perfectly match the hi-printed printed in the fourth pair of printing units. This is a problem especially on the edges of wide paths. This so-called register or fan-out problem is seen as blurred color images on the printed surface. Dot doubling, which causes undesirable tones in a printed image, can also be the result of dimensional changes in the substrate between the printing units.

In addition, porous water-absorbent pressure substrates should be dried at high temperatures. The web temperature can exceed 100 ° C after 0.2 s in the dryer and the web outlet temperature can be close to 150 ° C. Drying at such high temperatures causes fiber roughening, weighing and blowing. This is a problem especially in the printing of paper which comprises mechanical fibers. One reason for the occurrence of fiber rise is the rapid evaporation of moisture from a porous, coated printing substrate as the meadow pressure opens fiber bonds. Weighing is the permanent emergence of road patterns in the pressure. The weighing mechanism is not detailed in detail, but it is a result of uneven moisture outflow from the substrate due to high temperature drying. Blast formation due to high temperature drying may, however, be appreciable that the base sheet delaminates. Blow bubbles can also lead to web breaks during printing. The modern heatset roll offset printing process also usually uses a lot of energy. The air temperatures in the dryer can typically reach 250 ° C.

Thus, there is a desire to create a printing substrate with which these problems can be overcome.

In the conventional art, these problems have been attempted to overcome by providing a printing substrate with a non-porous, oleophilic surface.

WO2004030917 refers to a coated printing substrate having an oleophilic surface, which substrate exhibits a Gurley-Hill permeability value exceeding 5000 s / 100 ml, and an IGT color deposition value exceeding 0.6 pressure density units at a delay interval of 30 s. an oleophilic surface is meant that the surface rejects the moisture water, it being obvious that the contact angle to the water on the surface exceeds 90 °.

However, originating from the moisture of the base paper cannot readily evaporate from a closed, non-porous substrate, such as described in WO2004030917. This causes an elevated meadow pressure within the substrate and leads to serious pressure quality problems, such as fiber rise and blistering. These problems can occur even if the exit temperature of the web from the dryer is below 115 ° C, as mentioned in WO2004003293, since the maximum web temperature is not normally at the exit of the web but somewhere in the dryer.

In addition, certain oleophilic surfaces, such as those described in WO2004030917, tend to be also properly hydrophobic. If the non-porous surface is too hydrophobic, the continuous flow of moisture water from the printing plate is disturbed via the printing cloth into the paper. The moisture water concentrates in the printing unit, which can be detected as printing defects on certain image surfaces. On the other hand, if the surface is too hydrophilic, the forces between the substrate and the water are higher than the forces between the substrate and the oil. Thus, the water on the substrate's surface repels color, which can lead to a lower color strength and uneven pressure.

The substrate described in WO2004003293 is coated with flat pigments, such as kaolin and talc. Kaolin and taik are relatively expensive pigments compared to e.g. calcium carbonate. In addition, flat pigments, such as kaolin and taik, cause printing paper with a lower whiteness compared to e.g. calcium carbonate.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a printing substrate which avoids the disadvantages of the prior art.

It is a further object of the invention to provide a printing substrate for heatset roll offset printing, which has excellent dimensional stability and enables position energy drying.

Another object of the invention is to provide a pressure substrate for heatset roll offset printing, which causes low weighting and low fiber backing and improved crack resistance.

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It is a further object of the invention to provide a printing substrate with improved print quality and driving characteristics.

The above-mentioned objects and other advantages are achieved by obtaining a printing substrate according to claim 1. The printing substrate may be e.g. a substrate containing fibers, preferably a substrate containing cellulose fibers, such as paper or cardboard.

The pressure substrate of the invention has a Cobb (w15) water absorption value below 15 g / m2, preferably below 12 g / m2, a Cobb (o, C10) oil absorption value below 1.2 g / m2, preferably below 1 g / m2 and a color. -10 setting below 0.5, preferably below 0.3. The Cobb (w15) water absorption value is preferably within 1-15 g / m 2, most preferably within 2-15 g / m 2, and Cobb (o, C 10) is within 0.2-1.2 g / m 2, most preferably within 0.3-1 g / m2.

The low water and oil absorption in combination with the rather rapid coloration of the substrate according to the invention enables a printed substrate with improved printing qualities. The substrate according to the invention exhibits low water absorption, but it still leaves the steam to penetrate the structure, avoiding problems such as blistering. In addition, the moisture water transferred onto the substrate is prevented from entering the substrate structure due to the low water absorption. In this way, no harmful changes in the dimensions of the substrate occur due to fiber swelling, and incorrect alignment and point doubling are avoided. Good dimensional stability also enables the use of wide webs in printing with sharp images (good alignment) and good tone rendering, which affects the development of wider heatset rolloff set presses. Low water absorption also enables improved productivity and fewer cloth washes are required, as the paper surface retains its good hydrogen strength. In addition, other hydrogen web problems, such as web stress problems and web breakage, are avoided, as the moisture water does not penetrate the fibrous inner structure and cause changes in the fiber bonding. This improves the driving characteristics of the offset printing. Moisture water consumption is reduced due to the low water absorption, which is economically advantageous.

In an advantageous embodiment, the printing substrate exhibits a further 90 ° contact angle to the water. In this way, water is transferred from the printing cloth to the hydrophilic printing substrate, enabling a continuous flow of moisture water from the printing unit to the paper. Most preferably, the contact angle to water is below 90 ° but above 60 °. This prevents the substrate from becoming too hydrophilic. This avoids problems with low color strength and uneven pressure.

In another embodiment of the invention, the printing substrate is a substrate containing fiber, such as paper or cardboard, and is coated with a coating composition comprising a pigment composition.

The pigment composition preferably comprises calcium carbonate.

Calcium carbonate is economically presumptuous to use as pigment, since calcium carbonate is a relatively inexpensive pigment. In addition, calcium carbonate may possibly improve the whiteness of the paper. Most preferably, the pigment composition comprises calcium carbonate in an amount of more than 10%, most preferably in an amount of more than 20% of the pigment composition. This further improves the optical properties of the substrate.

In an advantageous embodiment, the pigment composition comprises fine-grained particle-sized micrometer-sized spheres, nanometer-sized calcium carbonate particles, and binder comprising a copolymer containing as monomer at least one dicarboxylic acid and at least one monomer selected from the group selected from the group and trialquanolamine. This specific composition enables control of the water absorption properties and porosity of the paper, since etch separation of the calcium carbonate particles from the talc particles is avoided. In addition, the substrate, according to the invention, captures small amount of absorbed water and solvent of nanostore pigment in the coating structure and is prevented from migrating into the substrate's base sheet.

The pigment composition preferably comprises taik and calcium carbonate in a ratio of about 3: 1-1: 3, most preferably in a ratio of 2: 1. The tallow content improves the surface's water repellency and pours the coloration at an appropriate level.

The substrate according to the invention enables good dry and hydrogen strength, which together with the low water absorption of the substrate further prevents the tendency of the coating material to be stored on the offset printing cloth. This allows for the use of a fast dye substrate and a slightly drying slightly sticky dye, which allows drying of the printed substrate at low temperatures. Problems regarding drying at high temperature, such as fiber rise and friability, are thereby minimized. The specific surface properties of the substrate according to the invention enable the use of a light drying color, e.g. As described in EP 1602696 A 1. This allows drying of the pressure at temperatures selected such that the maximum path temperature obtained in the drying 6 is kept below 130 ° C, preferably below 100 ° C. Drying of the printed substrate according to the invention at such low temperatures results in a printed substrate having a higher moisture content. A high moisture printed substrate has a better crack resistance as it is folded in a finishing process and exhibits no static electricity problems in the processing of printed signatures. Crack resistance is especially required in the staple stitching step in the magazine line as staples are printed through the folds of the printed sig-nature originating from various printed editions and then closed on the underside. Incidentally, the moisture remains even in the base sheet, reducing the weight of the printed signature. Also, the problem of internal paper swelling out of the bookbands is avoided due to the high moisture content of the printed substrate. High pressure in the substrate is further minimized due to low temperature drying. This improves the printing quality as the fiber rise is minimized and allows the use of a base sheet with reduced z strength, as there is no risk of blistering.

The invention also relates to a printed substrate comprising said printing substrate and heatset offset ink printed on the substrate, and a heatset roll offset printing method comprising printing said printing substrate in said at least one heatset roll offset printing unit and drying said substrate at said substrate. The drying is preferably carried out at a temperature selected such that the maximum obtained bed temperature in the dryer is below 130 ° C, preferably below 100 ° C.

The printing substrate according to the invention is most suitable for heatset offset printing, but can also advantageously be printed e.g. in sheet-fed offset and gravure printing procedures. Although the foregoing discussion regarding the benefits of the printing substrate is mainly related to the heatset roll offset printing, it is clear that even in sheet-fed offset printing, the low water absorption of the printed substrate provides good dimensional stability and water resistance properties which are particularly good for products, such as maps and food packaging materials. Use of the printed substrate in deep printing enables the use of water-based paint, since the low water absorption generates the broad dimensional stability required in wide webs.

DETAILED DESCRIPTION

It has been discovered that an improved printing quality can be achieved by using a low water absorption pressure substrate but which still allows even penetration of the substrate. According to the present invention, such a substrate is accomplished by providing a base paper and a coating recipe intended to achieve low Cobb water and Cobb oil values and rapid coloration.

In one embodiment of the invention, such a substrate is provided by the provision of a base paper having a coating composition comprising a pigment composition, which pigment composition comprises inorganic or organic microparticles, inorganic nanoparticles, and a binder. The binder in the pigment composition is preferably a copolymer comprising as a monomeric at least one dicarboxylic acid and at least one monomer selected from the group of diamine, triamine, dialkanolamine and trialkanolamine. In this way, the microparticles are covered by the nanoparticles, and segregation between the nanoparticles and the microparticles is avoided, whereby water absorption and pore structure can be controlled.

In this context, microparticles mean that the spherical diameter of the particles is in the micrometer size, i.e. within 0.3-100 µm, preferably between 1-25 µm. The microparticles are preferably particulate Taik, preferably plate-like Taik, since Taik improves the surface's water repellency and maintains the coloration at appropriate levels.

By nanoparticles is meant that the spherical diameter of the particles is in nominal size, ie. below 200 nm. The nanoparticles are preferably particulate calcium carbonate. Calcium carbonate is a cheap pigment and provides good optical properties. The calcium carbonate may be precipitated calcium carbonate (PCC) or ground calcium carbonate (GCC).

In one embodiment of the invention, the nano-calcium carbonate is ground calcium carbonate (GCC), which is ground in the presence of a hydrophobic generating agent, e.g. ethylene-acrylic acid copolymer (EAA). The hydrophobic generating agent reduces the water absorption of the nanocalcium carbonate and thus further reduces the water absorption of the pressure substrate.

Other pigments, such as calcined clay, TiO2 and plastic pigments, can be used alternatively or in addition in the pigment composition.

The pigment binder which prevents the separation between the nanoparticles and the microparticles may be e.g. a copolymer from adipic acid with N-2-aminoethyl) -1,2-ethanediamine and epichlorohydrin. The amount of binder present in the pigment composition is preferably about 2% of the total amount calculated from the microparticles.

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The coating composition may further comprise one or more binders for bonding the pigment composition to the surface of the substrate. This binder may be natural or synthetic and may include, but is not limited to starch, protein and latex.

Other additives, such as lubricants, can also be added in the composition.

The base paper can be any kind of base paper that heist. The coating composition can be applied to one or both sides of the base paper for a wide range of coatings, e.g. in an amount of 5-40 gsm per 10 pages, preferably in an amount of 10-20 gsm per page. The coating can be applied to the base paper using any coating technique heist, e.g. a glue press, roller or beam application, beam coating, blade coating or ridging coating. The base paper may be multilayer coated, e.g. double coated, one of the coating layers being the coating composition described herein and the other being a conventional coating composition. The printing paper according to the invention, i.e. the base paper, coated with the coating composition intended to achieve low Cobb values and rapid coloration, can be further coated e.g. with an extra, customary coating composition. Alternatively, the base paper 20 may first be coated with a conventional coating composition, after which the coating composition intended to provide low Cobb values and rapid coloration will form a top layer on top of the first custom coating composition. In this way, the optical properties of the printing substrate can be further enhanced. The coated paper may be calendered, e.g. in a super-calendar.

The invention is described in the following in more detail with reference to some examples. It will be understood that the invention is not limited to the particular process steps and materials described herein.

MEASUREMENT AND VALUATION PROCEDURES

Cobb Unger (o, CU10) is measured according to SCAN 37:77, CU 10.

This method determines the oil absorbency of the paper or cardboard. According to this method, the amount of castor oil absorbed per unit area is measured on one side of the paper or carton in the course of 10 seconds under specified circumstances.

Cobb Unger (w15) is measured using ISO 535: 1991 (E). IN

In accordance with this process, the amount of water absorbed is measured within a specified time of 1 m2 of paper or paperboard in the course of 15 seconds under specified circumstances. The conditioning atmosphere is according to ISO 187 (23 ° / 50% RH).

Coloring is determined in accordance with Pmfung von Druckpapieren, 5 Merkblatt V / 32/99. Color deposition is a measure of the color setting rate of the substrate. The printed substrate is brought into temporary contact with an opposing printing paper in a printing unit under defined line printing and at fixed time intervals. The staining that results from the transfer of the color to the opposing paper is then measured with an optical densitometer. The measurement is performed according to Zellcheming standard V731793 with a color amount of 1.5 g / m2 on the surface of the paper. The lower the color setting value, the faster the color setting. In the example below, the color used is Wegschlagtestfarbe Michael Huber Miinchen 520068 06.09.06, 0.100. The counteracting paper used is Scheufelen APCO II / II. The air conditioning is according to ISO 187 (23 ° C / 50% 15 RH). The test direction is the pressure direction, parallel to the machine direction. The time intervals are: 15 s, 30 s, 60 s, 120 s, 300 s. The color value is given at 60 s. The printing machine used is the PrQfbau Probean printer. In printing the substrate, endless vulcanized rubber with 65 ° Shore hardness is used as a printing form. In the printing paper of the opposing paper, an aluminum printing form is used. The printing substrate / counter mold is 200 N / cm.

Porosity is measured using an automatic Micromeritics porosity meter, Auto Pore III 9405. The range is 0.01-0.001 pm and the measurement is performed according to the pressure intervals shown in Annex I. According to the mercury porosimetry method, the porosity is characterized by applying varying pressure levels to a mercury-immersed sample. As the pressure increases during analysis, the pore size of each pressure point is calculated and the corresponding amount of mercury required to fill these pores is measured.

Contact angle is measured using SCAN P 18:66. According to this method, the shape of small water droplets is measured over the surface of the substrate. If the substrate rejects water, the droplet becomes ball shaped. If the water moistens the substrate, the drop is flatter. The water-repellent or water-attracting properties can be detected by measuring the angle whose one catheter is the droplet base on the surface of the substrate and the other catheter is the droplet's tangent in the immediate vicinity of the surface. In the example shown below, the winkein is measured after 0.1 s and the conditioning atmosphere is according to ISO 187 (23 ° / 50% RH).

The K&N dye absorbent is matured in accordance with SCAN-P 70:95 by using a special, K&N-supplied dye to evaluate the absorption of the dye in the substrate surface. The K&N color absorbance is measured by the percentage reduction in the whiteness of the surface as the K&N color is applied for 2 minutes and then 5 is removed. The smaller the number of color absorbents, the more non-porous the coating is and a lesser degree of color is thus penetrated into the coating.

Weighing is measured with a Lehmann profiler, AS300. This instrument works with a laser and detects the crayon contour on the printed surface. The weighting index is calculated by the square of the slope of each road, averaging several weights in different printed ranges. The lower the weighting index, the lower the weighing.

The ink's tack is measured with a Thank-O-Scope device in accordance with ISO 12634. Test conditions are as follows: amount of color 0.4 ml, stabilization time 30 s, stabilization speed 50 m / min, testing speed 150 m / min, temperature 30 ° C. The maximum color stick and the time of the maximum paint stick were taken from the stick curve to describe the drying properties of the paint. The shorter the time for the maximum tack, the faster the color drying tendency. The tack value characterizes the force required for cleavage of a color foil during color transfer between the substrate and the printing cloth. A lower sticking value indicates a lower cleavage force and a lower paper strength requirement.

Passes to fail are measured with a Prufbaii Deltack instrument. In this process, color is transferred to a paper substrate, after which the resulting color layer is split every three seconds. The ink color increases during the test as the ink is applied to the paper. The operator visually observes how many times the color splitting can take place before the paper surface is broken. The number of color splits is called Passes to fail. The higher the number, the better the surface strength of the printing substrate. The color used in this test is Huber Wegschlaget testfarbe ink 520068. The preset printing press (unit A) is 800 N, the printing press (unit B) 250 N, the printing speed is 0.5 m /, the temperature is 18 ° C and the color quantity 190 pl.

Napping is defined as the removal of individual particles from the surface of the paper, ie. abrasion of the surface of the paper or paperboard during the printing process.

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Dry snapping is measured with a Multipurpose Printability Tester produced by Pmfbau, Munich with the following settings: Color temperature: 23 ° C Application pressure: 150 N / cm 5 Rubber printing form 4 cm wide

Short sample pressure carrier Printing speed 0-3.0 m / s increasing In accordance with this test, the paper is printed at an increasing speed with a Prufbau Probean pressure instrument. The color splitting power increases as the transfer rate of the ink on the paper increases. With a certain color transfer rate, the color splitting force exceeds the strength of the paper surface, which can be seen by the removal of individual particles from the paper. In this test, the speed at which the napping is started in units m / s is given. The higher the strength of the paper surface, the higher the speed at which the tapping begins.

In the example below, the following color is used by Michael Huber, Munchen:

No. 2 (408002) normal setting * (lnko 14.8)

Nr3 (408003) high stick values * (lnko19.5) Hydrogen sampling is measured with a Multipurpose printability tester with a humidifier supplied by Priifbau, Munchen with the following settings: Color temperature: 23 ° C Application pressure: 15 kp / cm Rubber printing pressure 4 cm wide 0.5-4.0 m / s (constant) in increments of 0.5 m / s

Time interval between wetting and printing units = 1 s In the water tapping test, the paper is moistened first. After 1 s, the moistened paper is printed at a constant speed with a Prufbau Probeandruck instrument. At a certain color transfer rate, the ink splitting force exceeds the wetting strength of the paper surface, which can be seen as removing the coating layer particles from the pressure. In this test, the velocity at which hydrogen tapping is first observed in units m / s is given. The higher the surface strength of the paper surface, the higher the speed at which the tapping takes place. The example below uses color from Michael Huber, MOnchen: 12

No. 2 (408002) normal tack values * (lnko 14.8)

No. 3 (408003) high tack values * (lnko 19.5) EXAMPLE 1 The base paper used in the example below was Neo-

Press G uncoated base paper, 36 gms, comprising 50% bleached softwood pulp of the Nordic type (NBSK) and 50% mechanical pulp.

Three samples of the base paper were coated with coating compositions, which included pigment compositions containing talc particles and milled calcium carbonate particles in various proportions, as presented in Table 1.

TABLE1 __PI__P2 P3

Talc: CaCQ3 25:75 33:66 50:50

The talc particles used in the pigment compositions have spherical diameters in micrometer size, the ground calcium carbonate particles have spherical diameters in nanometer size. The pigment compositions further comprise an adipic acid copolymer with N- (2-aminoethyl) -1,2-ethanediamine and epichlorohydrin as the binder.

The pigment compositions were prepared according to Examples 1a and 1b below. The examples show the preparation of P1 and P3. Pigment Composition P2 was prepared in the same manner as P3, but with different proportions of calcium carbonate and talc. In the preparation of P2, the additives and reaction components were recalculated to the same proportions as in the preparation of P3.

EXAMPLE 1A, P1 PREPARATION Particulate talc 1:

The particulate talc used in Example 1a is Finntalc P 05 Powder, MONDO Minerals, Finland.

Binder 1:

The binder is a 15% aqueous solution of an adipic acid copolymer with N-2-aminoethyl) -1,2-ethamine diamine and epochlorohydrin with the following characteristics:

Total chlorine content: 1.5% by weight 13

Organic chlorine content: <0.5 wt% MW> 1000 g / mol

Brookfield viscosity of the aqueous solution: 80 mPa * s +/- 30 mPa * s.

pH 3.0 The said binder can be produced e.g. by producing an intermediate (1) by reaction of diethylenetriamine, monoethanolamine and adipic acid in distilled water. The resulting intermediate (1) is reacted with epichlorohydrin using sulfuric acid and calcium sorbate as a catalyst. The solids content is then adjusted to 12-20% by weight by the addition of water, and the pH is adjusted to pH 3 by the addition of sulfuric acid.

Nanoparticle calcium carbonate 1:

The nanoparticle calcium carbonate is produced by continuous milling of Norwegian marble particles with an equivalent diameter of 45 µm. The grinding is carried out in the presence of 0.85 wt% sodium / magnesium polyacrylate, calculated from the total dry weight of the composite, with a MW of 6000 g / mole, as the grinding additive, and 1 wt% polyethylene-polyacrylic acid copolymer sodium salt, calculated from the composite material total dry weight. The nanocalcium carbonate is ground to a dry content of 72% by weight with the particle size shown in Table 2.

TABLE 2

Diameter [nm] __ Number (N) of particles in N% __ W% <200 ___ 96.5__26.1 200-400 ____ 2J__20 400-600__05__17.8 600-800 0J__13.3 800-1000 <0.1 8.8

Production of pigment composition P1: 400 kg of particulate talc 1 milled for 10 minutes in a KFM 2000 D Batch Mixer / Dryer in the presence of 53.3 kg aqueous binder 1. The mixture is then homogenized for another 10 minutes, whereby an intermediate (2 ) is obtained.

77.5 kg of nanoparticle calcium carbonate 1 is mixed with 17.5 kg of water. 180 g of a 42 wt% aqueous solution of polyacrylic acid sodium salt (MW: 4000 g / mol, pH: 8.5) is then added to the solution and homogenized 2 ml 14 nits. The slurry is mixed with the intermediate (2) for 30 minutes. The mixture is then filtered through a 104 µm sail.

The resulting composite has a Brookfield viscosity (after 5 days) of 108/109/112 mPa * s, pH of 8.86 and dry matter content of 64.76% by weight.

In the resulting composite, the nanoparticle calcium carbonate is not segregated from the microparticle talc.

EXAMPLE 1B, P3 PREPARATION Particulate talc 1:

The particulate talc used in the example is Finntalc P 05 10 Powder, MONDO Minerals, Finland.

Binder 1:

The binder is a 15% aqueous solution of an adipic acid copolymer with N-2-aminoethyl) -1,2-ethanediamine and epichlorohydrin, as described in Example 1a.

Nanoparticle calcium carbonate 2:

The nanoparticle calcium carbonate is produced by continuous milling of Norwegian marble particles with an equivalent diameter of 45 µm. The milling is carried out in the presence of 0.85% by weight of sodium / magnesium polyacrylate, calculated from the total dry weight of the composite, with a MW of 6000 g / mole, as the milling additive calculated from the total dry weight of the composite. The sodium calcium carbonate is ground to a dry content of 72% by weight with the particle size shown in Table 3.

TABLE 3

Diameter [nm] __ Number (N) of particles in N% __ W% <200__9M__23.6 200-400__2.0__22.4 400-600__0.4__18.7 600-800__0J__14 800-1000> 0.1 9.3 Production of pigment composition P1 : 400 kg of particulate talc 1 milled for 10 minutes in a KFM 2000 D Batch Mixer / Dryer in the presence of 53.3 kg aqueous binder 1. The mixture is then homogenized for another 10 minutes to give an intermediate (3).

522.6 kg of nanoparticle calcium carbonate 2 are mixed with 388 kg of water. 8.9 kg of a 42 wt% aqueous solution of polyacrylic acid sodium salt and 3 kg of NaOH (10 wt%) are then added to the solution. The sludge is mixed with the intermediate (3). The mixture is then filtered through a 104 µm sage.

The resulting composite has a Brookfield viscosity (after 5 days) of 76/75/77 mPa (measured after 5/60/170 min), pH of 8.65 and dry matter content of 58.6% by weight.

In the resulting composite, the nanoparticle calcium carbonate is not segregated from the microparticle talc.

EXAMPLE 1B, PREPARATION OF THE PRESSURE SUBSTRATE

Three different coating compositions were prepared using pigment compositions P1, P2 and P3.

The coating compositions were prepared as presented below in Table 4.

Table 4 __Cl__C2__C3_ Pigment Section __ [Parts / Weight] __ [Parts / Weight __ [Parts / Weight] _P1___100__0__0_PP____0__100__0__ _P3__0__0__100

Binder Part [Parts / Pigment [Parts / Pigment [Parts / Pigment ___ Weight] ___ Weight] __ Weight] __

Latex DL 950 12 12 12 (styrene butadiene latex) ____

NopcoteC104 0.2 0.2 0.2 (calcium stearate lubricant) __________

Mowiol 6-98 0.3 0.3 0.3 _ (PVA binder) ____

Sterocoll HT 0.8 0.5 0.2 (synthetic thickener) ____

Coating Properties _

Coating 53.5 61.1 62.6 Solid [%] ____

Viscosity Brookfield 1230 790 1060 [mPas] ____ pH 8.6 8.5 8.6 15 16

The printing substrates thus produced were printed in a heated roller offset printing press. The printing press used was an Albert-Frankenthal A 101 S heatset roller offset printing press with four cloth-to-cloth printing units and a four-frame module 8 m long MEG Sigma hot air dryer. The pressure rate was 50,000 5 cpls / h (= 6.2 m / s), printed web exit temperature directly after the dryer was 90 ° C and after the cooling rollers 18.1 ° C. The moisture used in the printing consisted of 3% Huber Hit Redufix-R and 5% IPA with a temperature of 10 ° C, a conductivity of 740 pS / cm and a pH of 5.6. The print cloths were the Day Durazone 5000. The ink used was the Huber Group 25 H series color with the following characteristics, measured with a Thank-O-Scope and, by comparison, is another commercial color (caption color A is Huber Group's 29 H 3800 Rollo- Therm series). As can be seen below, the color used in printing is of a very fast drying type with short-term tili maximum tack and the color stick is low.

Time for maximum tack Maximum stress

25 H Color A 25 H Color A

Black 251 s 961 s 152 192

Cyan 158 s 444 s 114 192

Magenta 124 s 769 s 94 192

Yellow 143 s 761 s 127 209 15

Substrate properties, i.e. staining, Cobb (w15), Cobb (o, C10), contact angle to water, surface pore size and K&N absorbance, were measured for each substrate S1, S2, S3 in accordance with the measurement and evaluation procedures described above. For comparison, the same measurements were made on a reference substrate, NovaPress (R1), 70 gsm, which is a commercially available MWC offset paper produced by Stora Enso Publication Paper, Veitsiluoto mill. NovaPress is coated with a coating composition, which includes calcium carbonate and clay and is calendered on a Supercalender with 12 rolls in a stack.

The printing substrates S1, S2 and S3 according to the invention and the properties of the reference R1 are shown in Table 5.

17 TABLE 5 I S1 I S2 I S3 I R1

Cobb (w15) [g / m2] __ 9.9 10.3 3.8 26

Cobb (o, C10) fg / m21__0.84 0.96 0.63 2.7 Coloring (60s) __ 0.02 0.02 0.12 0.14

Porosity [cm2 / m3] __ 2J) __ 2J) __ 2J__5.5

The moisture content of the paper prepress [%] 4.3__4J) __ 4 ^ 0__3.5 K&N absorbance [%] I 2.7 I 3 3.7 7.7

The contact angle was determined to be 86.1 ° after 0.1 s for S3.

The print quality was evaluated by measuring the weight of the printing substrates S1, S2 and R1 according to the above-described method and by visual characterization. For the paper substrates S1, S2 and S3, water and dry picking were also determined. For the paper substrates S2 and R1, Passes to fail were determined in accordance with the procedure described above. The results of the weighing, napping and Passes to fail measurements are shown in Table 6.

10 TABLE6 I S1 | S2 I S3 | R1 Weighing__TL6 ___ 11.6 15.6 Hydrogen trapping *) resistance FS [mis] __ 2J) __ 2.5> 4.0__

Torm Mapping Resistance FS [m / s] __ 0.8> 3.0> 3.0__

Passes to fail [No.] __ 8__5 *) S1 and S3 are measured with color n. 2 and S3 with color n 3. as described in the procedure descriptions of water and dry sampling tests.

As Table 5 shows, the weighting tendency was significantly lower for the paper of the invention compared to the known reference. The paper according to the invention had a high dry and hydrogen tapping resistance and a better surface strength (Passes to fail) which, in combination with the low water absorption, allows the use of a fast-setting color. In addition, the printed surface of S1, S2 and S3 was much smoother and less rough compared to R1.

Although specific embodiments and examples of products and methods of the invention have been shown and described, it will be apparent to one skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects as defined in the appended patent claims. .

18

ANNEX I

Press Press Press

Number [MPa] Number [MPa] Number [MPa] 1 0.0351 41 1.9991 81 13.9311 2 0.0406 42 2.1967 82 14.2148 3 0.0604 43 2.3592 83 14.5709 4 0 0803 44 2,5239 84 14,8596 5 0,1003 45 2,6554 85 15,2299 6 0,1252 46 2,8544 86 15,5721 7 0,1501 47 3,0295 87 16,3823 8 0,185 48 3 , 2629 88 16.9829 9 0.2099 49 3.4937 89 17.5186 10 0.2413 50 4.0492 90 18.1955 11 0.2768 51 4.5916 91 18.8334 12 0.2873 52 5.4959 92 20,1199 13 0,3008 53 5,7921 93 21,1192 14 0,3186 54 6,1855 94 23,9643 15 0,3492 55 6,6149 95 24,4351 16 0,4055 56 6,983 96 25,0901 17 0.4546 57 7.6079 97 28.9628 18 0.5019 58 7.9799 98 32.2049 19 0.553 59 8.3988 99 34.2826 20 0.5977 60 8.7862 100 36.7433 21 0.6507 61 9,0198 101 39,0274 22 0,6989 62 9,3084 102 41,4373 23 0,7509 63 9,6878 103 46,1483 24 0,7974 64 10,0456 104 48,4397 25 0,85 65 10 , 3432 105 50.852 26 0.9012 66 10.509 106 53.2377 27 0.9509 67 10.724 107 55.6331 28 0.9992 68 10.9551 108 58.1834 29 1.0475 69 11.158 109 60.4795 30 1.125 70 11,3517 110 65,1204 31 1,2053 71 11,5598 111 67,677 9 32 1,2508 72 11,7114 112 69,8604 33 1,2727 73 11,8947 34 1,3025 74 12,0943 35 1,4483 75 12,3066 36 1,574 76 12,4522 37 1,6299 77 12, 6887 38 1.7063 78 12.9838 39 1.8493 79 13.3224 40 1.9533 80 13.5873

Claims (11)

A printing substrate for intaglio and offset printing having: (i) a Cobb (w15) value of less than 15 g / m2, (ii) a Cobb (o, C10) value of less than 1.2 g / m2, preferably less than 1 g / m2 and 5 (iii) a color value of less than 0.5, preferably less than 0.3. The printing medium of claim 1, further comprising an angle of contact with water not exceeding 90 °. A printing medium according to any one of the preceding claims, wherein the substrate is coated with a coating composition comprising a pigment composition. The printing medium of claim 3, wherein the pigment composition comprises calcium carbonate. The printing medium of claim 4, wherein the pigment composition comprises calcium carbonate in an amount of at least 10%, preferably at least 20%, of the pigment composition. A printing medium according to any one of the preceding claims, wherein the pigment composition comprises a fine talc having micrometre spherical diameter, nanometric sized calcium carbonate particles and a binder comprising a copolymer comprising at least one dicarboxylic acid monomer and at least one dicarboxylic acid monomer, -20 bases formed by diamine, triamine, dialkanolamine and trialkanolamine. The printing medium of any one of claims 3 to 6, wherein the pigment composition comprises calcium carbonate and talc in a ratio of about 3: 1 to 1: 3. A printed substrate comprising a printed substrate according to any one of claims 1-7; as well as heat-set roll offset ink printed on the substrate. A heat set roll offset printing process, comprising the steps of: printing a substrate according to any one of claims 1 to 7 in at least one heat set offset printing unit; and drying said substrate. The heat-set roll offset printing process according to claim 9, wherein the drying is carried out at a temperature such that the temperature of the web during drying is below 130 ° C, preferably below 100 ° C. A sheet fed offset printing method, comprising printing a substrate according to any one of claims 1 to 7.