JP6282604B2 - Coated paper for on-demand printing - Google Patents

Description

  The present invention relates to a coated paper for on-demand printing, and more particularly to a coated paper for on-demand printing having ink jet printing suitability.

  The main commercial printing is offset printing using cast paper, art paper, coated paper, finely coated paper, non-coated plain paper, coated paperboard, etc. Therefore, an on-demand printing method capable of handling variable information such as a dry electrophotographic method, a wet electrophotographic method, and an ink jet method has been developed. Among these printing methods, the inkjet method is compatible with wide printing and high-speed printing, so an inkjet print head is installed in the offset printer, and the fixed information is variable by offset printing. The method of performing information by ink jet printing has been increasing.

  In recent years, ink jet printers have been increased in speed by adopting a line head, and the printing speed has reached 20 m / min or more for winding printing and 120 m / min or more for high speed printing. A high-speed aqueous inkjet printer having a printing speed of 20 m / min or more has a dryer in the machine in order to dry the aqueous ink. Recently, as an alternative to offset printing, there has been a growing demand for color printing using only the inkjet printing method. In order for the inkjet printing method to grow in the commercial printing field in the future, it has the same level of printing as offset printing, ink absorbency suitable for high-speed aqueous inkjet printing that does not cause stains due to poor ink drying, and is available at a low cost It has the appearance of general-purpose coated paper and coated paperboard such as cast paper, art paper, coated paper, and fine coated paper, which are used in large quantities in general commercial printing, and is generally used for offset printing and letterpress printing. The emergence of printing paper that also has commercial printability is important.

  The ink jet printing method is a method in which dye ink or pigment ink is ejected from a nozzle onto the surface of a recording sheet to form an image and print. In the inkjet printing system, there is a strong tendency to use cheap water-based ink as compared with solvent ink and UV ink from the viewpoint of running cost.

  Coated paper and coated paperboard used in general commercial printing cannot be absorbed on the paper surface due to image bleeding, especially when printing by high-speed ink jet, especially in the case of color printing, because the ink absorption speed is extremely slow. There are problems such as density unevenness (beading) due to ink collection and paper stains due to poor drying. The high-speed water-based inkjet printer has a dryer, but the current situation is that the drying of the ink is not in time when coated paper or coated paperboard used in general commercial printing is used. The reason for this is that the coating layer of coated paper and coated paperboard used in general commercial printing may be mainly composed of pigments with relatively poor ink absorbability such as calcium carbonate and kaolin. The inclusion of a lubricant in the work layer is also considered to be a major factor. That is, in such coated paper and coated paperboard, calendar processing is performed to give glossiness and smoothness. However, in calendar processing, dusting (roll dirt) is likely to occur. Use lubricant in the coating layer. However, since a commonly used lubricant has water repellency, the water repellency of the lubricant reduces the ink absorbency of the ink jet, resulting in inadequate drying of the ink.

  On the other hand, special-purpose inkjet paper for coated paper type has an ink-receiving layer with high ink absorbency, which is mainly composed of pigments with a large specific surface area such as amorphous silica and alumina, and water-soluble adhesives such as PVA. doing. Therefore, even if printing is performed with a high-speed ink jet printer, the ink absorbability is good, and the problem of paper stains due to bleeding, density unevenness, and poor drying does not occur. However, since the ink-receiving layer strength is weak, offset printing cannot be performed, the appearance is different from general coated paper, and it is expensive, so it is not suitable for use as a general-purpose printing paper.

  Several proposals have been made as a method for improving the water-based inkjet method of coated paper and coated paperboard used in general commercial printing. A coated paper for printing in which the particle size and blending amount of kaolin and the binder component are limited to an appropriate range as the pigment used in the coating layer (see, for example, Patent Document 1), and carbonic acid as the pigment used in the coating layer A coated paper for printing (see, for example, Patent Document 2) in which the oil absorption amount of calcium is limited to an appropriate range has been proposed.

JP 2009-233925 A JP 2004-82464 A

  However, the coated paper disclosed in Patent Document 1 and Patent Document 2 described above does not have practically sufficient ink absorbability. For this reason, the printing speed is not suitable for high-speed inkjet printing using aqueous ink having a printing speed of, for example, 14.85 m / min or more for a sheet or 20 m / min or more for a roll paper.

  The present invention has been made in view of such problems, and an object of the present invention is to be suitable for offset printing and letterpress printing, which are general commercial printing, while being inexpensive and capable of high-speed inkjet printing. It is to provide coated paper for on-demand printing.

  As a result of intensive studies on paper suitability in high-speed ink jet printing using water-based ink (hereinafter sometimes referred to as “high-speed water-based ink jet printing”), the present inventors contain a pigment, an adhesive, and a lubricant. It has been found that the problem can be achieved by increasing the liquid absorbency of the base paper to which the ink receiving layer is applied.

That is, the on-demand printing coated paper according to the present invention is a printing coated paper that is provided with an ink-receiving layer on at least one side of a base paper and is subjected to a calendar process, and the base paper includes an internal sizing agent and It contains no external sizing agent, contains an internal paper strength enhancer, and the coating amount of the surface paper strength enhancer on the surface of the base paper is 0 g / m ² or more per both sides in terms of solid content 0.5 g / m ² or less, the ink receiving layer contains a pigment, a styrene butadiene latex, and a lubricant, 40% by mass or more of the pigment is light calcium carbonate, and the printing speed is a sheet of paper. It is for high-speed inkjet printing using a water-based ink of 14.85 m / min or more and roll paper of 20 m / min or more. Ink absorbability in high-speed aqueous inkjet printing can be improved. Further, the ink drying property can be improved.

The coated paper for on-demand printing according to the present invention is a coated paper for printing that is provided with an ink receiving layer on at least one side of a base paper and is subjected to a calendering process, wherein the base paper comprises an internal sizing agent and an external additive. It contains no sizing agent, contains an internal paper strength enhancer, and the coating amount of the surface strength enhancer on the surface of the base paper is 0 g / m ² or more per both sides in terms of solid content . 5 g / m ² or less, the ink receiving layer contains a pigment, a styrene butadiene latex, and a lubricant, and 40% by mass or more of the pigment is calcium carbonate, and light calcium carbonate and heavy as the calcium carbonate It is characterized by being for high-speed ink jet printing using aqueous ink containing both calcium carbonate and a printing speed of 14.85 m / min or more for sheet paper and 20 m / min or more for roll paper. Ink absorbability in high-speed aqueous inkjet printing can be improved. Further, the ink drying property can be improved. The ink absorbency in high-speed aqueous inkjet printing can be improved while further reducing the cost.

In the coated paper for on-demand printing according to the present invention, it is preferable that 40% by mass or more of the pigment is light calcium carbonate and further contains heavy calcium carbonate.

  In the coated paper for on-demand printing according to the present invention, the lubricant preferably contains one or more higher fatty acid salts. It is difficult to inhibit ink absorbency in high-speed aqueous inkjet printing.

  In the coated paper for on-demand printing according to the present invention, the ink receiving layer preferably further contains starch. The surface strength of the ink receiving layer can be further increased. Moreover, cost can be suppressed more.

  INDUSTRIAL APPLICABILITY The present invention can provide a coated paper for on-demand printing that is inexpensive and has high-speed inkjet printing aptitude, and has general commercial printing offset printing aptitude and letterpress printing aptitude.

  Next, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

  The on-demand printing coated paper according to the present embodiment is a printing coated paper obtained by providing an ink-receiving layer on at least one side of a base paper and performing a calendar process. The base paper includes an internal sizing agent and an external sizing agent. It contains no additive sizing agent and contains an internally added paper strength enhancer, the ink receiving layer contains a pigment, a styrene butadiene latex, and a lubricant, and 40% by mass or more of the pigment is calcium carbonate. Yes, it is for high-speed inkjet printing using aqueous ink with a printing speed of 14.85 m / min or more for sheet paper and 20 m / min or more for roll paper. By adopting such a configuration, the ink jet ink that has landed on the surface of the ink receiving layer is quickly absorbed into the ink receiving layer and the base paper, thereby suppressing smearing during transport after printing due to bleeding or poor drying. it can. Further, by using an internal paper strength enhancer, it is possible to prevent paper peeling in general commercial printing.

  As the base paper of the on-demand printing coated paper according to the present embodiment, paper mainly composed of raw material pulp, an internal paper strength enhancer, and a filler is used. As raw material pulp, for example, wood pulp or non-wood pulp can be used. Wood pulp is, for example, chemical pulp such as LBKP (hardwood bleached kraft pulp), NBKP (softwood bleached kraft pulp), GP (ground wood pulp), PGW (pressure ground wood pulp), RMP (refiner mechanical pulp), TMP (thermo). Mechanical pulp such as mechanical pulp), CTMP (chemi-thermo mechanical pulp), CMP (chemi-mechanical pulp), CGP (chemi-ground pulp), and DIP (deinked pulp). Non-wood pulp is, for example, kenaf, bagasse, bamboo, and cotton. These raw material pulps can be used alone or mixed at an arbitrary ratio. Synthetic fibers can also be used as long as the effects of the present invention are not impaired. From the viewpoint of environmental conservation, ECF (Elemental Chlorine Free) pulp, TCF (Totally Chlorine Free) pulp, DIP, and pulp obtained from planted trees are preferable.

  The raw material pulp is made into a pulp slurry having a suitable degree of freeness by using a disintegrator and a beater. The freeness is preferably 350 to 580 ml, and more preferably 380 to 550 ml. If it is less than 350 ml, the air permeability is deteriorated, the absorbability of the high-speed inkjet printer ink is hindered, and bleeding, beading and drying may be caused. If it exceeds 580 ml, the strength of the base paper will be insufficient, and problems such as paper peeling, powder falling off during general commercial printing, and paper surface peeling during paper processing may occur. The pulp slurry is prepared by blending a filler and an internal paper strength enhancer.

  As the internal paper strength enhancer, a conventionally known paper strength enhancer can be used. Examples of the internal paper strength enhancer include starch based paper strength enhancing agents, polyacrylamide based paper strength enhancing agents, polyvinyl alcohol based paper strength enhancing agents, wet paper strength enhancing agents, and the like, which may be used alone or in combination. In the present invention, a starch-based paper strength enhancer is preferred. Since the starch-based paper strength enhancer is unlikely to hinder the air permeability of the base paper, the absorbability of the ink-jet ink in high-speed aqueous ink-jet printing is good and it is inexpensive. Examples of the starch-based paper strength enhancer include cationized starch, amphoteric starch, grafted starch, and pregelatinized starch.

  It is preferable that the compounding quantity of an internal paper strength enhancer is 0.2-2.0 mass parts with respect to 100 mass parts of dry mass of a pulp. More preferably, it is 0.3-1.7 mass part. More preferably, it is 0.4-1.5 mass parts. If the amount is less than 0.2 parts by mass, the strength of the base paper is insufficient, and problems such as paper peeling and powder falling during general commercial printing, and peeling of the paper surface layer during paper processing may occur. If it exceeds 2.0 parts by mass, dirt may be generated in the paper making process and defects such as impurities and holes may occur on the paper surface.

  A conventionally known filler can be used as the filler. Examples of the filler include calcium carbonate, talc, kaolin, calcined kaolin, titanium oxide, aluminum hydroxide, and white carbon, which are used alone or in combination. In the present invention, calcium carbonate, calcined kaolin and white carbon are preferred. These fillers enhance the ink absorbency of the base paper, and therefore the absorbency of the high-speed inkjet printer ink is good. The filler content in the paper is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the dry mass of the pulp. More preferably, it is 3-17 mass parts. If it is less than 2 parts by mass, the ink absorbability is insufficient, and the effect of improving whiteness and opacity is difficult to obtain. When the amount exceeds 20 parts by mass, the strength of the base paper is insufficient, and problems such as paper peeling and powder falling during general commercial printing, and peeling of the surface layer of the paper during paper processing may occur.

  The coated paper for on-demand printing according to the present embodiment is configured such that the base paper does not contain an internal sizing agent and an external sizing agent. The reason for this is to increase the absorbability of inkjet ink to coated paper in high-speed aqueous inkjet printing. Although details will be described later, a lubricant is included in the ink receiving layer provided on the on-demand printing coated paper according to the present embodiment in order to suppress dusting during the calendar process. Since the lubricant inhibits the ink-jet ink from being absorbed into the coated paper due to its water repellency, poor drying of the ink tends to occur. However, if the base paper does not contain the internal sizing agent and the external sizing agent, poor ink drying due to the lubricant can be improved. The reason for this is not clear, but it is thought that the base paper itself does not contain a sizing agent, so that the ink absorbability of the base paper itself is increased, and the decrease in ink absorbability of the ink receiving layer due to the lubricant is covered. . In addition, by not containing a sizing agent in the base paper, the absorption speed of the ink for ink jet onto the base paper is increased, but the ink that has landed on the surface of the ink receiving layer does not spread appropriately as ink dots, resulting in white streaks. May occur. However, by including a lubricant in the ink receiving layer, excessive absorption of ink on the surface of the ink receiving layer is suppressed, and the ink dots spread appropriately, so that the print quality can be maintained as a result. Conceivable. In any case, there is a perfect balance between the fact that the base paper does not contain an internal sizing agent and an external sizing agent, and that the ink receiving layer contains a lubricant, and ink drying in high-speed aqueous inkjet printing. And the printing quality can be made good. In the present specification, the internal sizing agent is, for example, a neutral rosin sizing agent, a reinforced rosin sizing agent, a saponified rosin sizing agent, an acidic rosin sizing agent, a weak acidic rosin sizing agent, an alkenyl succinic anhydride, an alkyl ketene dimer, or styrene. -Acrylic sizing agent, styrene-maleic acid sizing agent, higher fatty acid amide sizing agent, olefin sizing agent, acrylate sizing agent, and wax sizing agent. Examples of the externally added sizing agent include a styrene-acrylic sizing agent, a styrene-maleic acid sizing agent, an olefin sizing agent, an alkyl ketene dimer, and a wax sizing agent.

  In addition, known additives such as bulking agents, yield improvers, freeness improvers, sulfuric acid bands, cationizing agents, coloring dyes, coloring pigments, fluorescent whitening agents, fluorescent decoloring agents, etc. The present invention can be used as appropriate as long as the effects of the invention are not impaired.

  The base paper can be obtained, for example, by making a paper with a paper machine. The paper machine is not particularly limited. Various types of paper machines such as a long paper machine, a multi-layer paper machine, a circular paper machine, a circular multi-layer paper machine, a long-mesh multi-layer paper machine, a twin wire paper machine, etc. An apparatus can be used. The papermaking method is not particularly limited, and either acidic papermaking or neutral papermaking can be selected. However, neutral papermaking is preferred when calcium carbonate is used as a filler.

The basis weight of base paper is not particularly limited, is preferably 40~500g / ^{m 2,} more preferably 50~450g / ^{m 2.}

In the coated paper for on-demand printing according to this embodiment, the surface paper strength enhancer may not be applied to the surface of the base paper, or the surface paper strength enhancer may be applied to the surface of the base paper. By not applying a surface paper strength enhancer to the surface of the base paper, it is possible to improve the ink absorbability in high-speed aqueous inkjet printing, suppress bleeding, and improve the drying property. In addition, by applying the surface paper strength enhancer, the suitability in terms of strength during various printings can be improved, and the occurrence of dusting can be suppressed. However, if the surface paper strength enhancer is applied too much, the air permeability of the coated paper for on-demand printing deteriorates, impeding ink absorbency in high-speed aqueous inkjet printing, and causing problems such as bleeding and poor drying. Therefore, it is preferable to keep the coating amount low. When the surface paper strength enhancer is applied to the surface of the base paper, the coating amount of the surface paper strength enhancer on the surface of the base paper is preferably 2.5 g / m ² or less per both sides in terms of solid content. The coating amount of the surface paper strength enhancer on the base paper is preferably 0.1 to 2.5 g / m ² on both sides of the base paper in terms of solid content. More preferably, it is 0.2-1.0 g / m < ² >, More preferably, it is 0.3-0.5 g / m < ² >.

  As the surface paper strength enhancer applied to the surface of the base paper, a conventionally known paper strength enhancer can be used. Examples of the surface paper strength enhancer include a starch-based surface paper strength enhancer, a polyvinyl alcohol-based surface paper strength enhancer, a polyacrylamide-based surface paper strength enhancer, and a polyamide epoxy-based surface paper strength enhancer. Used in combination. In the present invention, a starch-based surface paper strength enhancer and a polyacrylamide-based surface paper strength enhancer are preferred. Examples of the starch-based surface paper strength enhancer include oxidized starch, cationized starch, amphoteric starch, grafted starch, phosphate esterified starch, and self-modified starch. Autogenous denaturation is, for example, denaturation by enzymatic or thermochemical action. Examples of the polyacrylamide surface paper strength enhancer include anionic polyacrylamide, nonionic polyacrylamide, and cationic polyacrylamide.

  On one side or both sides of the base paper obtained by the above method, a coating liquid mainly composed of a pigment and a binder is applied and then dried to provide an ink receiving layer. The ink receiving layer may be a single layer or a laminate of two or more layers.

  As the pigment contained in the ink receiving layer, it is possible to use a white pigment used in conventionally known general printing coated paper. Examples of the white pigment include calcium carbonate (light calcium carbonate, heavy calcium carbonate), kaolin, calcined clay, zinc oxide, titanium oxide, aluminum hydroxide, and plastic pigment, and are used alone or in combination. Among these, since it is preferable to contain calcium carbonate which is inexpensive but has relatively high ink absorbability, in the present invention, 40% by mass or more of the total pigment is calcium carbonate. Preferably 60 mass% or more is calcium carbonate. More preferably, 75% by mass or more is calcium carbonate. More preferably, 85% by mass or more is calcium carbonate. By making calcium carbonate into 40% by mass or more of the total pigment, it is possible to obtain a coated paper for on-demand printing that is inexpensive and easily available and can be applied to general commercial printing. Moreover, as calcium carbonate, light calcium carbonate is preferable. By blending light calcium carbonate into the ink receiving layer, the ink absorbability in high-speed aqueous inkjet printing is improved, and the ink drying property is particularly improved. The total amount of calcium carbonate contained in the ink receiving layer is preferably light calcium carbonate, but light calcium carbonate and heavy calcium carbonate may be used in combination. By using light calcium carbonate and heavy calcium carbonate in combination, the ink absorbency in high-speed aqueous inkjet printing can be improved while further reducing costs.

  The ink receiving layer contains styrene butadiene latex as a binder. By using styrene butadiene tex, the strength of the ink receiving layer can be improved. In the present invention, as a binder used in the ink receiving layer, in addition to styrene butadiene latex, it is also possible to use a binder used in conventionally known general coated paper for printing. Examples of binders that can be used in combination with styrene butadiene latex include starches such as acrylonitrile butadiene latex, oxidized starch, enzyme-modified starch, esterified starch, etherified starch, cationized starch, and amphoteric starch, acrylic resins, polyurethane resins, and polyesters. Examples of such resins include polyamide resins, polyamide resins, polyvinyl alcohol or modified products thereof, gelatin, casein, soybean protein, vinyl acetate, ethylene vinyl acetate, carboxymethyl cellulose, and hydroxyethyl cellulose, which are used alone or in combination. A combination of styrene butadiene latex and starch is more preferred. By combining styrene butadiene latex and starch, the ink receiving layer strength can be further increased. Moreover, cost can be suppressed more. When the styrene butadiene latex and other binder are used in combination, the blending ratio is not particularly limited, but the ratio of the styrene butadiene latex is preferably 60% by mass or more in the total mass of the binder, 70% by mass. % Or more is more preferable.

  Although the compounding quantity of the binder to an ink receiving layer is not specifically limited, It is preferable that it is 3-30 mass parts with respect to 100 mass parts of pigments in an ink receiving layer, More preferably, it is 5-20 mass parts. If it is less than 3 parts by mass, the strength of the ink receiving layer is insufficient, and problems such as picking of the ink receiving layer during general commercial printing may occur. When it exceeds 30 parts by mass, the absorbability of the high-speed inkjet printer ink may be hindered, and bleeding and drying problems may occur.

  Moreover, in the coated paper for on-demand printing according to the present embodiment, a lubricant is contained in the ink receiving layer. By including a lubricant in the ink receiving layer, it is possible to suppress the dusting of the calender roll during the calendering process in addition to the above-described effects of improving the ink drying property and the print quality. The blending amount of the lubricant in the ink receiving layer is preferably 0.05 to 3 parts by mass, more preferably 0.05 to 2.5 parts by mass with respect to 100 parts by mass of the pigment in the ink receiving layer. It is. If the amount is less than 0.05 parts by mass, the dusting prevention effect is inferior, which may cause problems such as contamination of the calendar roll and a decrease in glossiness. When the amount exceeds 2.5 parts by mass, the ink absorbability in high-speed aqueous inkjet printing is hindered, and there is a risk of problems of bleeding and poor drying. When two or more ink receiving layers are laminated on the base paper, the lubricant may be contained only in the ink receiving layer that is the outermost layer.

  Examples of the lubricant used here include an aqueous lubricant and an emulsion lubricant. Specifically, higher fatty acid salts, polyethylene emulsions and the like can be used. Among these, it is particularly preferable that the lubricant contains one or more higher fatty acid salts. By containing a higher fatty acid salt, it is difficult to inhibit the ink absorbency in high-speed aqueous inkjet printing. Higher fatty acid salts are, for example, stearates, palmitates, and oleates. These may be used alone or in combination of two or more.

  In addition, the ink receiving layer may contain various auxiliary agents as necessary, such as antifoaming agents, dispersants, fluorescent whitening agents, coloring dyes, coloring pigments, viscosity modifiers, preservatives, water resistance agents, and UV absorbers. Further, an antioxidant, a water retention agent, a crosslinking agent, a pH adjuster, a conductive treatment agent, an internal gelling agent, a gloss imparting agent, and the like may be appropriately blended.

  The ink receiving layer can be provided by applying a coating liquid for the ink receiving layer on the surface of the base paper and drying it. Coating methods for the ink receiving layer include air knife coaters, roll coaters, bar coaters, rod blade coaters, short doll coaters, curtain coaters, comma coaters, blade coaters, spray coaters, gravure coaters, and dies. A coating machine, a Chanplex coater, a metering blade type size press coater, a gate roll coater, a shim sizer and the like can be appropriately selected from known coating machines and used on-machine or off-machine. The ink receiving layer may be provided on one side of the base paper or on both sides.

The coating amount of the ink receiving layer per one side of the base paper is preferably 3~40g / ^{m 2} in terms of solid content, and more preferably a 5 to 30 g / ^{m 2.} If it is less than 3 g / m ² , the surface of the base paper may not be sufficiently covered, and there is a possibility that the print dot reproducibility and the print density in general commercial printing as coated paper and high-speed aqueous inkjet printing cannot be satisfied. When it exceeds 40 g / m ² , it is disadvantageous in terms of cost.

  The coated paper for on-demand printing of the present invention is calendered after an ink receiving layer is provided on the base paper. By the calendar process, the paper thickness profile can be flattened and the glossiness of the coated paper surface can be controlled. Further, by performing a calendar process, an appearance equivalent to that of coated paper used in general commercial printing can be obtained. As the calendar processing apparatus, a hard nip calendar, a soft calendar, a super calendar, a metal belt calendar, a raster press, or the like is used. In order to increase the glossiness, a soft calender, a super calender, or the like is preferable, and the glossiness is controlled according to the pressure pressure, the number of pressure nips, and the temperature conditions.

  The on-demand printing coated paper according to the present embodiment has inkjet suitability and is suitable for high-speed inkjet printing using aqueous ink. In the present specification, high-speed inkjet printing refers to inkjet printing using aqueous ink of 14.85 m / min or more for sheet paper and 20 m / min or more for roll paper. 14.85 m / min or more for a sheet corresponds to, for example, 50 sheets / min or more of A4 size vertical stitches. Further, the on-demand printing coated paper according to the present embodiment is not limited to use as a high-speed inkjet printing paper and general commercial printing paper, but also a recording paper for a dry electrophotographic copying machine or printer, a wet electrophotographic printing paper. Can be used as recording paper for copiers and printers.

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, “parts” and “%” represent “parts by mass” and “mass%”, respectively, unless otherwise specified. The number of added parts is a value in terms of solid content.

( Reference Example 1)
(Preparation of base paper A)
100 parts of EBK bleached LBKP as a pulp is beaten to 550 ml of freeness to obtain a pulp slurry, and 1.5 parts of cationized starch (Neotack 30T: manufactured by Nippon Food Processing Co., Ltd.) as an internal paper strength enhancer is added to the pulp slurry. 15 parts of light calcium carbonate (TP121: manufactured by Okutama Kogyo Co., Ltd.) and 1 part of a sulfuric acid band were added to prepare a stock. This stock was made with an on-top type twin-wire paper machine to prepare a base paper having a basis weight of 60 g / m ² . Next, in a gate roll device, a coating solution having a 12% concentration of oxidized starch (Ace A: manufactured by Oji Corn Starch Co., Ltd.) as a surface paper strength enhancer is applied to both surfaces of the base paper, and the coating amount per both surfaces is 2.4 g. / ^{m 2} and comprising as coating, followed by drying to produce a base paper a having a basis weight of 62.4 g / ^{m 2.}

(Preparation of coating liquid A for ink receiving layer)
As a pigment, 40 parts of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.), 60 parts of kaolin (Ultra White 90, manufactured by Engelhard), and 0.1 part of a dispersant (Aron T-50, manufactured by Toagosei Co., Ltd.) in water. It was added and dispersed in water using a coreless disperser to prepare a pigment slurry. To this pigment slurry, 2 parts of starch (MS4600, manufactured by Nippon Food Processing Co., Ltd.) and 10 parts of styrene butadiene latex (PA0372, Nippon A & L Co., Ltd.) as a binder, and higher fatty acid salt (DEF-963TF, Nissin Chemical Laboratory) as a lubricant Co., Ltd.) 0.2 part was added, and water was further added to prepare a coating liquid A for an ink receiving layer having a solid concentration of 60%.

(Preparation of coated paper for on-demand printing)
Apply coating liquid A on both sides of base paper A on both sides of base paper A using an on-machine blade coater so that the coating amount per side of base paper A is 10 g / m ² in terms of solid content. Worked and dried. Thereafter, a hard nip calendar process was performed as a calendar process, and a coated paper for on-demand printing having a basis weight of 82.4 g / m ² was produced.

( Reference Example 2)
In Example 1, except that the freeness of LBKP of base paper A was changed to 380 ml, and the amount of cationized starch (Neotack 30T: manufactured by Nippon Food Processing Co., Ltd.) as an internal paper strength enhancer was changed to 0.2 parts Produced a coated paper for on-demand printing in the same manner as in Reference Example 1.

( Reference Example 3)
Reference Example 1, Coating Solution precipitated calcium carbonate in A: a (TP123CS Okutama Kogyo Co., Ltd.) 40 parts of heavy calcium carbonate (Kabitaru 75: Imerys manufactured Minerals, Inc.) was changed to 40 parts Reference Example 1 In the same manner, coated paper for on-demand printing was prepared.

( Reference Example 4)
In Reference Example 1, the amount of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.) in coating solution A was changed to 75 parts, and the amount of kaolin (Ultra White 90, manufactured by Engelhard) was changed to 25 parts. A coated paper for on-demand printing was produced in the same manner as in Reference Example 1 except that.

( Reference Example 5)
In Reference Example 1, the amount of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.) in coating liquid A was changed to 85 parts, and the amount of kaolin (Ultra White 90, manufactured by Engelhard) was changed to 15 parts. A coated paper for on-demand printing was produced in the same manner as in Reference Example 1 except that.

( Reference Example 6)
In Reference Example 1, the composition of the pigment in the coating liquid A is 60 parts of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.), 25 parts of heavy calcium carbonate (Carbital 75: manufactured by Imeris Minerals Co., Ltd.), kaolin (ultra white) (90, manufactured by Engelhard) A coated paper for on-demand printing was prepared in the same manner as in Reference Example 1 except that the amount was changed to 15 parts.

( Reference Example 7)
In Reference Example 1, the coating solution applied to the base paper using the gate roll device was changed to a coating solution having a 6% concentration of oxidized starch (Ace A: manufactured by Oji Cornstarch Co., Ltd.) as a surface paper strength enhancer. A coated paper for on-demand printing was prepared in the same manner as in Reference Example 1 except that the coating amount per both sides was 1.0 g / m ² in terms of solid content. The basis weight of the base paper was 61.0 g / m ² .

(Example 8)
(Preparation of base paper B)
100 parts of EBK bleached LBKP as a pulp is beaten to 550 ml of freeness to obtain a pulp slurry, and 1.5 parts of cationized starch (Neotack 30T: manufactured by Nippon Food Processing Co., Ltd.) as an internal paper strength enhancer is added to the pulp slurry. 15 parts of light calcium carbonate (TP121: manufactured by Okutama Kogyo Co., Ltd.) and 1 part of a sulfuric acid band were added to prepare a stock. The paper stock was made with an on-top type twin wire paper machine to prepare a base paper B having a basis weight of 60 g / m ² .

(Preparation of coated paper for on-demand printing)
On both sides of the base paper B, the coating liquid A of Example 1 was applied to both sides of the base paper using an on-machine blade coater so that the coating amount per side of the base paper was 10 g / m ² in terms of solid content. Coated and dried. Thereafter, a hard nip calendar process was performed as a calendar process, and a coated paper for on-demand printing having a basis weight of 80.0 g / m ² was produced.

Example 9
In Example 8, the freeness of LBKP of the base paper B was changed to 380 ml, and the internal additive paper strength enhancer was changed from 1.5 parts of cationized starch (Neotack 30T: manufactured by Nippon Food Processing Co., Ltd.) to amphoteric starch (CATO308: Japan). A coated paper for on-demand printing was prepared in the same manner as in Example 8 except that the content was changed to 0.4 part (manufactured by NSC).

( Reference Example 10)
In Example 8, with the exception of changing 40 parts of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.) of coating liquid A to 40 parts of heavy calcium carbonate (Carbital 75: manufactured by Imeris Minerals Co., Ltd.) Similarly, a coated paper for on-demand printing was produced.

(Example 11)
In Example 8, except for changing 40 parts of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.) to 40 parts of light calcium carbonate (TP221GS: manufactured by Okutama Kogyo Co., Ltd.), for on-demand printing. Coated paper was prepared.

(Example 12)
In Example 8, the amount of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.) in coating liquid A was changed to 75 parts, and the amount of kaolin (Ultra White 90, manufactured by Engelhard) was changed to 25 parts. A coated paper for on-demand printing was produced in the same manner as in Example 8 except that.

(Example 13)
In Example 8, the amount of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.) in coating liquid A was changed to 85 parts, and the amount of kaolin (Ultra White 90, manufactured by Engelhard) was changed to 15 parts. A coated paper for on-demand printing was produced in the same manner as in Example 8 except that.

(Example 14)
In Example 8, the composition of the pigment in the coating liquid A was 60 parts of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.), 25 parts of heavy calcium carbonate (Carbital 75: manufactured by Imeris Minerals Co., Ltd.), kaolin (Ultra White). (90, manufactured by Engelhard) A coated paper for on-demand printing was prepared in the same manner as in Example 8 except that the amount was changed to 15 parts.

(Example 15)
A coated paper for on-demand printing was produced in the same manner as in Example 8, except that the calendar process was changed from the hard nip calendar process to the super calendar process in Example 8. The produced on-demand printing paper had the appearance of glossy paper.

(Example 16)
(Preparation of coating liquid B for ink receiving layer)
90 parts of heavy calcium carbonate (Carbital 75: manufactured by Imeris Minerals), 10 parts of kaolin (Ultra White 90, manufactured by Engelhard), 0.1 part of dispersant (Aron T-50, manufactured by Toagosei Co., Ltd.) in water And dispersed in water using a coreless disperser to prepare a pigment slurry. To this pigment slurry, 2 parts of starch (MS4600, manufactured by Nippon Food Processing Co., Ltd.) and 8 parts of styrene butadiene latex (PA0372, Nippon A & L Co., Ltd.) are added as binders, and water is further added to accept ink with a solid content concentration of 60%. A coating solution B for the layer was prepared.

(Preparation of coating liquid C for ink receiving layer)
60 parts of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo), 40 parts of kaolin (Ultra White 90, manufactured by Engelhard) and 0.1 part of a dispersant (Aron T-50, manufactured by Toagosei Co., Ltd.) are added to water. Water dispersion was performed using a Coreless disperser to prepare a pigment slurry. In this pigment slurry, 2 parts of starch (MS4600, manufactured by Nippon Food Processing Co., Ltd.) and 6 parts of styrene butadiene latex (PA0372, Nippon A & L Co., Ltd.) as a binder, and higher fatty acid salt (DEF-783TF, Nissin Chemical Laboratory) as a lubricant Co., Ltd.) 0.5 part was added, and water was further added to prepare a coating liquid C for an ink ink receiving layer having a solid concentration of 65%.

The basis weight of the base paper B in Example 8 was changed to 120 g / m ² , and the coating liquid B was applied to both sides of the base paper using an on-machine gate roll coater, and the dry coating mass per side was 8 g / Coating and drying were carried out to m ² . On both surfaces of the coating layer, the coating liquid C was coated and dried using an on-machine blade coater so that the dry coating mass per one surface was 8 g / m ² . Thereafter, a hard nip calendar process was performed as a calendar process, and a coated paper for on-demand printing having a basis weight of 152 g / m ² was produced.

(Example 17)
In Example 16, a coated paper for on-demand printing was prepared in the same manner as in Example 16 except that the calendar process was changed from the hard nip calendar process to the super calendar process.

(Comparative Example 1)
Reference Example 1, a neutral rosin sizing agent as an internal sizing agent in the base paper A: except for adding (CC1401 Seiko PMC Corporation) 0.2 parts, coated paper for print-on-demand in the same manner as in Reference Example 1 Was made.

(Comparative Example 2)
In Reference Example 1, the coating liquid applied to the base paper using a gate roll device is 12% oxidized starch (Ace A: manufactured by Oji Cornstarch) as a surface paper strength enhancer, and a styrene-acrylic sizing agent as an external sizing agent. (Polymarlon 1308S: manufactured by Arakawa Chemical Industries, Ltd.) Changed to a coating solution having a concentration of 0.4%, the coating solution is applied to both sides of the base paper, and the coating amount per both sides becomes a solid mass of 2.4 g / m ^2. A coated paper for on-demand printing was prepared in the same manner as in Reference Example 1 except that coating was performed as described above.

(Comparative Example 3)
In Reference Example 1, 0.2 parts of a neutral rosin sizing agent (CC1401: manufactured by Seiko PMC Co., Ltd.) as an internal sizing agent was added to the base paper A, and the coating liquid applied to the base paper using a gate roll device was applied to the surface paper. Changed to a coating solution with a concentration of 12% oxidized starch (Ace A: manufactured by Oji Cornstarch Co., Ltd.) as a force enhancer and 0.4% concentration of styrene-acrylic sizing agent (Polymarlon 1308S: Arakawa Chemical Industries Co., Ltd.) as an external sizing agent On-demand printing coated paper in the same manner as in Reference Example 1 except that the coating solution was applied to both sides of the base paper so that the coating amount per both sides was a solid mass of 2.4 g / m ^2. Was made.

(Comparative Example 4)
In Example 8, coating for on-demand printing was performed in the same manner as in Example 8 except that 0.2 parts of a neutral rosin sizing agent (CC1401: manufactured by Hoshiko PMC) was added to the base paper B as an internal sizing agent. Paper was made.

(Comparative Example 5)
In Reference Example 1, the amount of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.) in coating liquid A was changed to 30 parts, and the amount of kaolin (Ultra White 90, manufactured by Engelhard) was changed to 70 parts. A coated paper for on-demand printing was produced in the same manner as in Reference Example 1 except that.

(Comparative Example 6)
In Example 8, the amount of light calcium carbonate (TP123CS: manufactured by Okutama Kogyo Co., Ltd.) in coating solution A was changed to 30 parts, and the amount of kaolin (Ultra White 90, manufactured by Engelhard) was changed to 70 parts. A coated paper for on-demand printing was produced in the same manner as in Example 8 except that.

(Comparative Example 7)
In Example 8, 0.2 part of a neutral rosin sizing agent (CC1401: manufactured by Seiko PMC) was added to the base paper B as an internal sizing agent, and the internal paper strength enhancer of the base paper B was not added. A coated paper for on-demand printing was produced in the same manner as in Example 8 except that.

(Comparative Example 8)
In Example 8, except that 0.2 part of a neutral rosin sizing agent (CC1401: manufactured by Seiko PMC) was added to the base paper B as an internal sizing agent, and no lubricant was added to the coating liquid A. In the same manner as in Example 8, a coated paper for on-demand printing was produced.

  On-demand printing coated paper obtained in each Example and Comparative Example was tested based on the following evaluation method. The results are shown in Table 1, Table 2 and Table 3.

(1) Ink bleeding evaluation White characters were printed using the following two types of ink jet printers, and the bleeding status of the aqueous pigment ink was visually evaluated as follows.
Printer A: CM8060Color MFP (manufactured by Hewlett-Packard Company)
Bonding agent + water-based dye 4 colors (C, M, Y, K),
Printing speed 50 sheets / min A4 size.
Printer B: Truepress Jet 520 (Dainippon Screen Mfg. Co., Ltd.)
Printing speed 64m / min.
(Double-circle): There is no bleeding and it is favorable (practical level).
○: Slight bleeding occurs but good (practical level).
Δ: Some bleeding occurs (practical upper and lower limit level).
X: Bleeding occurs remarkably (impractical level).

(2) Evaluation of ink dryness Using the following inkjet printer C, black, cyan, magenta, and yellow water-based pigment inks were printed with a single solid color, and the ink traces due to poor ink drying on the printed paper surface were visually observed as follows. It was evaluated as follows.
Printer C: Truepress Jet 520 (Dainippon Screen Mfg. Co., Ltd.)
Printing speed 64m / min.
Dry 80 ° C
(Double-circle): There is no ink trace and it is favorable (practical level).
○: Slightly traces of ink taken (practical lower limit level).
Δ: Some ink traces occur (impractical level).
X: Traces of ink removal occur remarkably (impractical level).

(3) Printing durability Using Lilithron 40 (L-40) manufactured by Komori as an offset printing machine, printing four colors with ink, indigo, red and yellow ink at a printing speed of 8500 sheets / hour The printing durability was evaluated.
(Double-circle): There is almost no dirt of a blanket and it is good (practical level).
○: There is some dirt on the blanket, but there is almost no omission in the image area, which is good (practical level).
(Triangle | delta): There are many stain | pollution | contaminations of a blanket, and there exists omission of an image line part (practical level is impossible).
X: The blanket is severely soiled and the image area is often missing (practically impossible).

(4) Calendar roll stain The calendar roll stain was visually evaluated as follows.
(Double-circle): There is no dirt on the calendar roll surface, and it is very good. (Practical level)
○: Slight dirt is generated on the calendar roll surface, but it is good. (Practical level)
(Triangle | delta): The dirt on the surface of a calendar roll is much and is inferior. (Impractical level)
X: The surface of the calendar roll is considerably dirty and extremely inferior. (Impractical level)

As is clear from Tables 1, 2, and 3, Examples 8, 9 , and 11 to 17 have excellent suitability for general commercial printing paper as compared with Comparative Examples 1 to 8, and are excellent in inkjet printing. Yes.

By comparing Examples 8 , 9 , 11 to 17 and Comparative Examples 1 to 4, it was confirmed that the addition of the internal sizing agent and the external sizing agent was blurred and the drying property was inferior. By comparing Examples 8 , 9 , 11 to 17 with Comparative Examples 5 and 6, it was confirmed that blending and drying properties were improved by adding 60 parts or more of calcium carbonate in the ink receiving layer. . By comparing Example 8 and Comparative Example 7, it was confirmed that the printing durability was inferior by not adding the internal paper strength enhancer. By comparing Example 8 and Comparative Example 8, it was confirmed that the calendar roll dirt was inferior by not blending the lubricant.

  As an additional evaluation, low-speed inkjet printing suitability using water-based ink was confirmed.

(Ink bleeding evaluation)
For Reference Example 1 and Comparative Example 1, ink bleeding was evaluated using printer D by the same evaluation method and evaluation criteria as when printers A and B were used. As a result, Reference Example 1 was ○, and Comparative Example 1 was Δ.
Printer D: PX-G930 (manufactured by Epson Corporation)
Printing speed 3 sheets / min A4 size.

(Evaluation of ink drying properties)
For Reference Example 1 and Comparative Example 1, black, cyan, magenta, and yellow water-based pigment ink single-color solid single-sided printing was performed using printer D, and the printed paper was stacked on the paper discharge tray, and the ink on the printed paper surface Ink transfer due to poor drying was visually evaluated as follows. As a result, Reference Example 1 was ◎ and Comparative Example 1 was ○.
Printer D: PX-G930 (manufactured by Epson Corporation)
Printing speed: 3 sheets / minute A4 size: Excellent with no ink transfer (practical level).
○: Ink transfer slightly occurs (practical upper and lower limit level).
Δ: Some ink transfer occurs (impractical level).
X: Ink transfer remarkably occurs (impractical level).

From the above, Reference Example 1 had good bleeding and drying properties in both low-speed inkjet printing and high-speed inkjet printing. On the other hand, in Comparative Example 1, the bleeding / drying property was a practical level in the low-speed inkjet printing suitability, but it was confirmed that the bleeding / drying property was inferior in the high-speed inkjet printing.

Claims (5)

A coated paper for printing, which is provided with an ink receiving layer on at least one side of a base paper and is subjected to a calendar process,
The base paper does not contain an internal additive sizing agent and an external additive sizing agent, contains an internal additive paper strength enhancer, and the coating amount of the surface strength enhancer on the surface of the base paper is a solid content. In conversion, it is 0 g / m ² or more and 0.5 g / m ² or less per both sides ,
The ink receiving layer contains a pigment, a styrene butadiene latex, and a lubricant;
40% by weight or more of the pigment is light calcium carbonate,
A coated paper for on-demand printing, characterized in that it is for high-speed ink jet printing using aqueous ink with a printing speed of 14.85 m / min or more for sheet paper and 20 m / min or more for roll paper. A coated paper for printing, which is provided with an ink receiving layer on at least one side of a base paper and is subjected to a calendar process,
  The base paper does not contain an internal additive sizing agent and an external additive sizing agent, contains an internal additive paper strength enhancer, and the coating amount of the surface strength enhancer on the surface of the base paper is a solid content. 0g / m per side in conversion ² 0.5 g / m ² And
  The ink receiving layer contains a pigment, a styrene butadiene latex, and a lubricant;
  40% by mass or more of the pigment is calcium carbonate, and contains both light calcium carbonate and heavy calcium carbonate as the calcium carbonate,
  A coated paper for on-demand printing, characterized in that it is for high-speed ink jet printing using aqueous ink with a printing speed of 14.85 m / min or more for sheet paper and 20 m / min or more for roll paper. The coated paper for on-demand printing according to claim 2, wherein 40% by mass or more of the pigment is light calcium carbonate and further contains heavy calcium carbonate. The coated paper for on-demand printing according to any one of claims 1 to 3 , wherein the lubricant contains one or more higher fatty acid salts. The coated paper for on-demand printing according to any one of claims 1 to 4 , wherein the ink receiving layer further contains starch.