JP2012214012A - Coated paper for inkjet printing machine of rotation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated paper for inkjet rotary press which is excellent in ink absorbability and printing density, is capable of suppressing printing irregularities, and has a good operability of printing in inkjet printing of a rotation system while maintaining an offset printing suitability.SOLUTION: In the coated paper for inkjet printing machines of a rotation system in which an ink receiving layer principally composed of a pigment and a binder is prepared at least on one surface of a base paper, the base paper is a surface size press base paper formed by sizing pressing with a size press liquid that includes synthetic silica and a surface size agent.

Description

  The present invention relates to a coated paper for a rotary type ink jet printer. Further, the present invention relates to a coated paper for a rotary type ink jet printer which does not impair the offset printability.

  With the rapid advancement of ink-jet recording technology, it is possible to form color and high-quality images on recording media such as paper and film with printers that use the ink-jet recording method (hereinafter referred to as “ink-jet printers”). It became so. Among such inkjet printers, there are large format printers used by printers and the like from small home printers. Basically, these printers are used mainly in a small number of printing sites in order to perform printing in units of one sheet.

  In recent years, application of commercial printing (hereinafter referred to as “inkjet printing”) using an inkjet recording method has begun due to further technological advances. In the commercial printing field, the number of copies is large, and printing speed is emphasized from the viewpoint of productivity and printing cost. A printing speed suitable for inkjet printing is achieved by a printing machine (hereinafter referred to as “inkjet printing machine”) having a line head in which the head for ejecting ink is fixed in the entire width direction perpendicular to the paper conveyance direction. (For example, see Patent Document 1). Recently, rotary ink jet printers have been developed that are equipped with pigment inks having a printing speed of 15 m / min or higher, higher speeds of 60 m / min or higher, and higher speeds of 120 m / min or higher.

  Ink jet printers are particularly applied to on-demand printing because they can handle variable information. In commercial printing, it is preferable to print fixed information with an offset printer and print variable information with a rotary inkjet printer.

  However, when conventional offset printing coated paper is employed in a rotary inkjet printer, the printed image becomes dirty due to scratching after printing at the printing speed described above, and the offset printing coated paper is an inkjet ink. Insufficient absorbability causes problems such as uneven printing and blurring, and in severe cases, ink flow (a phenomenon in which unabsorbed ink flows on the coated paper surface) occurs. In addition, in order to compensate for the lack of ink absorbability, there is also a problem in that the print density decreases when the ink discharge amount is suppressed.

  When the binder of the coating layer is simply reduced in order to improve the ink absorbency or printing density of printing on a rotary inkjet printer, or when the porous pigment with high oil absorption is used in the coating layer In the case of coated paper for a rotary inkjet printer, offset printing suitability such as loss of coating layer strength and occurrence of blanking is impaired. Accordingly, a coated paper for a rotary inkjet printer is required to have sufficient printing density and ink-absorbing inkjet printing aptitude without impairing offset printing aptitude.

  As a trend of inks used in the above rotary inkjet printers, water pigment inks are increasingly used from the viewpoint of weather resistance in addition to water-based dye inks. As a problem of the aqueous pigment ink, there is a printing unevenness in a printing portion. Uneven printing is a phenomenon in which the ink absorbability of coated paper for inkjet printers varies when the printing speed is high, and the density of the fixed ink in the final printed image after the ink is dried becomes uneven. It is. Ink used for ink-jet printing has a low density of the color material, and printing unevenness is likely to be noticeable compared to offset printing. The commercial value of the printed matter is reduced by the printing unevenness, and therefore it is required to suppress the printing unevenness.

  There is an ink jet recording medium in which an ink receiving layer containing silica, calcium carbonate, and a binder is provided on a base paper using a transfer roll coater (see, for example, Patent Document 2). Such an inkjet recording medium is inferior in ink absorptivity and printing density in inkjet printing, although it is excellent in offset printing suitability. There is an ink jet recording medium in which an ink receiving layer containing silica, an emulsion, and a binder having an oil absorption of 201 ml / 100 g or more and 340 ml / 100 g or less is provided on a base paper using a size press (see, for example, Patent Document 3). Such an ink jet recording medium is excellent in ink absorbability and printing unevenness in an ink jet printer. However, it is inferior in ink absorptivity in an ink jet printer, and is inferior in offset printability due to insufficient strength of the coating layer.

  In addition, as an ink jet recording sheet that suppresses ink absorbability and print unevenness of a printed image, an under layer containing silica and a binder is provided on a support, and an ink receiving layer containing silica and a binder is also provided on the under layer. Inkjet recording sheets (for example, see Patent Document 4) and inkjet recording media in which an undercoat layer mainly composed of calcium carbonate is provided on a support and an ink receiving layer containing synthetic silica is provided on the undercoat layer. (For example, refer to Patent Document 5). However, these ink jet recording sheets are for ink jet printers and have poor offset printability. On the other hand, there is an ink jet recording paper having a coating layer mainly composed of an inorganic pigment and a binder on a base paper containing a cationic polymer (see, for example, Patent Document 6). Although the offset printability is good, it is excellent in terms of ink absorbency in ink jet printing, but is still not sufficient.

JP 2009-23292 A JP 2005-96434 A JP 2009-154323 A JP 2007-223145 A JP 2005-271444 A JP 2010-100039 A

  A coated paper for an inkjet printer having excellent aptitude for a rotary inkjet printer employing an aqueous dye ink or pigment ink has not been obtained without impairing offset printing aptitude. In addition, rotary inkjet printers are often rewound at a speed corresponding to the printing speed, and may be equipped with a dryer to promote ink drying before being rewound after printing. Many. In such a rotary inkjet printer, the coated paper may be twisted and wrinkled depending on the conditions of high speed, winding and drying. When winding wrinkles occur, printing operability such as stoppage or reduction in printing speed deteriorates.

  That is, the object of the present invention is (1) good offset printing suitability for coated paper for rotary inkjet printers, (2) sufficient ink absorptivity and print density in inkjet printing, 3) Satisfying that printing unevenness of the printed portion is sufficiently suppressed in ink jet printing employing pigment ink, and (4) that the operability of printing with reduced wrinkling is good.

  The above problem is that, in a coated paper for a rotary type ink jet printer in which an ink receiving layer mainly composed of a pigment and a binder is provided on at least one surface of the base paper, the base paper contains synthetic silica and a surface sizing agent. This can be solved by a rotary-type coated paper for inkjet printers, which is a surface-sized press base paper formed by size pressing with a size press liquid.

  Preferably, the pigment of the ink receiving layer contains at least one calcium carbonate or kaolin. Preferably, the synthetic silica has an average particle size of 0.3 μm or more and 7 μm or less.

  According to another aspect of the present invention, there is provided a printing method for a rotary inkjet printer, the step of obtaining the above-described rotary inkjet printer paper, and ink reception of the rotary inkjet printer paper Provided is a method including a step of forming a printed image on a layer by performing rotary inkjet printing using a pigment ink at a printing speed of 120 m / min or more. Further, the present invention is a method for forming an excellent printed image, the step of obtaining a coated paper for a rotary inkjet printer, and an ink receiving layer of the coated paper for a rotary inkjet printer, A method is provided that includes forming a printed image using an offset printer and / or a rotary inkjet printer.

  According to the present invention, it is possible to obtain a rotary-type coated paper for an ink jet printing machine having good offset printability and having good ink absorbability, print density and printing operability even in ink jet printing. In particular, even with a rotary ink jet printer equipped with pigment ink, a coated paper for a rotary ink jet printer with reduced printing unevenness in the printed portion can be obtained.

  Hereinafter, the rotary coated ink-jet printing paper of the present invention will be described in detail.

  In the present invention, the base paper before being size-pressed with the size press liquid, that is, the base paper that has not been surface-size-pressed is referred to as “raw base paper”. The raw base paper used for the coated paper for rotary printing ink-jet printers of the present invention is a sheet mainly composed of cellulose pulp and filler. Examples of cellulose pulp include chemical pulps such as LBKP and NBKP, GP, and PGW. , RMP, TMP, CTMP, CMP, CGP and other mechanical pulp, and DIP and other waste paper pulp are used alone or in combination. As the filler used in the raw base paper of the present invention, various known fillers such as calcium carbonate, talc and kaolin can be used alone or in combination.

  The raw raw paper of the present invention can be appropriately mixed with various additives such as sizing agent, fixing agent, retention agent, cationizing agent, wet paper strength enhancer, and dry paper strength enhancer in addition to cellulose pulp and filler. In addition, a paper stock appropriately blended with cellulose pulp and filler and various additives can be made with various paper machines such as a long net paper machine, a circular net paper machine, and a twin wire paper machine.

  In the present invention, in the stock forming raw green paper, as other additives, pigment dispersant, thickener, fluidity improver, antifoaming agent, antifoaming agent, release agent, foaming agent, A penetrant, a coloring dye, a coloring pigment, a fluorescent brightening agent, an ultraviolet absorber, an antioxidant, an antiseptic, an antibacterial agent, a water-proofing agent and the like are appropriately blended within a range not impairing the desired effects of the present invention You can also.

  Further, from the viewpoint of ink absorbability of ink-jet ink and printing unevenness, the ash content in raw raw paper is preferably 8% by mass or more and 25% by mass or less. If the amount of ash is less than 8% by mass, uneven printing tends to occur, and if the amount of ash exceeds 25% by mass, troubles such as picking or paper breakage during offset printing due to insufficient strength of raw raw paper may occur. More preferably, it is 10 mass% or more and 20 mass% or less.

  The amount of ash here is a ratio (% by mass) between the mass of incombustible material after burning raw paper at 500 ° C. for 1 hour and the absolutely dry mass of the raw paper before burning treatment. The amount of ash can be adjusted by the content of fillers in raw raw paper.

  In the present invention, the raw paper may be any sizing degree as long as the desired effect of the present invention is not impaired, and can be adjusted according to the type and amount of the internally added sizing agent. The internal sizing agent is, for example, rosin sizing agent for acidic paper, alkenyl succinic anhydride, alkyl ketene dimer, neutral rosin sizing agent or cationic styrene-acrylic sizing agent for neutral paper. is there. From the viewpoint of ink absorbability, the raw base paper is preferably low in size.

  In the present invention, the base paper is a surface size press base paper formed by size pressing a raw base paper with a size press liquid. The size press liquid is a liquid containing a surface sizing agent that is attached to raw paper by a size press. The surface sizing agent has a role of imparting water resistance and water penetration resistance to raw paper. Unlike the case where the internal sizing agent is present inside the raw paper, the surface-sized press base paper that has been size-pressed with the size press solution has a surface sizing agent that is present in the vicinity of the raw paper surface and expresses the required surface sizing properties. .

  Surface sizing agents include, for example, starch purified from natural plants, hydroxyethylated starch, oxidized starch, etherified starch, phosphate esterified starch, enzyme-modified starch, cold water soluble starch obtained by flash drying them, polyvinyl alcohol Or polyvinyl alcohol derivative, acrylic copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, acrylonitrile-vinyl formal-acrylic ester copolymer, styrene-maleic acid copolymer Olefin-maleic acid copolymer, alkyl ketene dimer system, rosin system and the like. Starch, polyvinyl alcohol, or derivatives thereof are preferred because of compatibility with synthetic silica described later.

  In the present invention, various known methods can be used for the size press. From the viewpoint of production cost, an on-machine coating method such as a size press installed in a paper machine is preferable. Size press methods include an incline size press, a horizontal size press, and a film transfer method such as a rod metering size press, a roll metering size press, and a blade metering size press. Examples include sizers, speed sizers, and film presses, and roll metal ring size presses include gate roll coaters. Other examples include bill blade coaters, twin blade coaters, bellbapa coaters, tab size presses, and calendar size presses. Preferred are an incline size press, a horizontal size press, a gate roll coater, a shim sizer, and a film press.

  The surface size press base paper used in the present invention is formed by size pressing with a size press liquid containing synthetic silica and a surface sizing agent. For example, synthetic silica, such as white carbon, tends to reduce sizing properties, which is not preferable in terms of sizing properties. The surface sizing agent has an action of suppressing water permeation into the raw paper, while the synthetic silica has an action of absorbing water. A coated paper having an ink-receiving layer mainly composed of a pigment and a binder on a surface-size press base paper having such an action has good ink absorbability and printing density corresponding to a rotary inkjet printer, and Suppression of printing unevenness in the pigment ink and good printing operability can be obtained.

  The effect of the present invention cannot be obtained with a surface size press base paper formed by size pressing with a size press liquid containing a surface sizing agent and calcium carbonate or kaolin. The reason for this is unclear, but it is considered that a unique structure is formed by some interaction when an ink receiving layer is provided on the surface-sized press base paper of the present invention. This is thought to be due to the superior porosity of synthetic silica compared to calcium carbonate or kaolin.

  As the synthetic silica in the present invention, synthetic silica such as wet method silica and gas phase method silica can be used. Wet method silica is classified into precipitation method silica, gel method silica, and sol method silica depending on the production method. Precipitated silica is generally produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the silica particles that have grown are agglomerated and settled, followed by filtration, washing, drying, pulverization and classification. Precipitated silica is commercially available, for example, as a nip seal from Nippon Silica Co., Ltd. as Toku Seal from Tokuyama Corporation. Gel silica is generally produced by reacting sodium silicate and sulfuric acid under acidic conditions. During the ripening, the fine particles dissolve and reprecipitate so as to bind the other primary particles, so that the distinct primary particles disappear and form relatively hard aggregated particles having an internal void structure. For example, it is marketed as a nip gel from Tosoh Silica Co., Ltd., and as a siloid and a silo jet from Grace Japan. The sol method silica is also called colloidal silica, and is generally produced by heating and aging a silica sol obtained through metathesis of sodium silicate acid or the like through an ion exchange resin layer. The sol method silica is commercially available from, for example, Nissan Chemical Industries as Snowtex.

  Vapor phase silica is also called dry silica, and is generally produced by flame hydrolysis. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state. Vapor phase silica is commercially available from Nippon Aerosil as Aerosil and from Tokuyama as Reolosil.

  These synthetic silicas can be used after being pulverized as required. The pulverization is performed by a known mechanical pulverizer such as a media mill such as a ball mill, a bead mill, or a sand grinder, a pressure disperser such as a high-pressure homogenizer or an ultra-high pressure homogenizer, an ultrasonic disperser, and a thin film swirl disperser Can do.

  The average particle diameter of the synthetic silica in the present invention is preferably in the range of 0.3 μm to 7 μm. Since it can enter into the recessed part formed between the fibers of raw raw paper within this range, a smooth surface-sized press base paper can be obtained. The average particle diameter is a value based on particle size distribution measurement using a laser diffraction / scattering method or a dynamic light scattering method.

  In the present invention, the content of the surface sizing agent in the size press liquid is preferably in the range of 3% by mass to 25% by mass with respect to the synthetic silica. Within this range, any of the effects according to the present invention is more excellent.

  In the present invention, the surface size press base paper is formed by size pressing a size press solution containing synthetic silica and a surface sizing agent. In the case of a size press, the synthetic silica is formed between the fibers of raw paper because pressure is applied during coating compared to the case where synthetic silica is applied with a general coating device such as an air knife coater or curtain coater. It goes further into the recessed part. As a result, a smooth surface-sized press base paper is obtained. Excellent ink for inkjet printing by combining the surface formed by size pressing with a size press liquid containing synthetic silica and surface sizing agent on the raw base paper, and the ink receiving layer formed on the smooth surface size press base paper It is possible to obtain a coated paper for a rotary type ink jet printing machine that has an absorptivity and printing density, can suppress printing unevenness, and has excellent printing operability. Since synthetic silica has water absorption, it does not impair the water absorbability of raw paper even when it enters a recess formed between fibers of raw raw paper.

  Whether or not it is a surface size press base paper formed by size pressing a size press liquid containing synthetic silica and a surface sizing agent is determined by observing the cross section of the coated paper with an electron microscope, between the fibers of the raw base paper. This can be determined from the state of entering the recess and the smoothness of the surface in contact with the ink receiving layer.

  In an ink jet recording medium for a so-called ink jet printer, in order to obtain ink absorbability, a lower ink receiving layer containing synthetic silica may be provided by a general coating apparatus. However, such an ink receiving layer does not have offset printing suitability in terms of coating layer strength.

  The size press liquid in the present invention can appropriately contain a pigment other than synthetic silica as long as the desired effects of the present invention are not impaired. For example, calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, aluminum hydroxide, alumina, lithopone, Examples thereof include white inorganic pigments such as zeolite, hydrous halloysite, magnesium carbonate and magnesium hydroxide, organic pigments such as styrene plastic pigment, acrylic plastic pigment, polyethylene, urea resin and melamine resin.

  In the size press liquid of the present invention, as additives, binder, dye fixing agent, pigment dispersant, thickener, fluidity improver, surfactant, antifoaming agent, antifoaming agent, mold release agent, foaming agent, It contains penetrants, colored dyes, colored pigments, fluorescent brighteners, UV absorbers, antioxidants, preservatives, antibacterial agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers, etc. as appropriate. You can also.

In the present invention, the coating weight of the size press solution per side 0.5 g / ^{m 2} or more 4.0 g / ^{m 2} preferably in the following range. Within this range, any of the effects according to the present invention is more excellent. In the present invention, the coating amount of the size press solution indicates the coating amount of the dry solid content.

  The coated paper for a rotary inkjet printer of the present invention has an ink receiving layer mainly composed of a pigment and a binder on a surface-sized press base paper. By providing the ink receiving layer, it is possible to differentiate from fine paper in terms of print quality and appearance. The main component is that the total of the pigment and the binder occupies 50% by mass or more in the dry solid content of the ink receiving layer.

  In the present invention, the ink receiving layer preferably contains at least one calcium carbonate or kaolin as a pigment. The content of calcium carbonate or kaolin in the ink receiving layer is 60 parts by mass or more, preferably 70 parts by mass or more with respect to 100 parts by mass of the total pigment in the ink receiving layer. The calcium carbonate or kaolin particles themselves do not absorb ink jet ink. However, the ink-jet ink can be absorbed by voids formed between particles caused by calcium carbonate particles or kaolin particles. The ink receiving layer contains calcium carbonate or kaolin in an amount of 60 parts by mass or more out of 100 parts by mass of the total pigment in the ink receiving layer, so that good ink absorptivity corresponding to an ink jet printer can be obtained without impairing offset printing suitability. Can have.

  Ink jet ink can be absorbed by the voids formed between the particles caused by calcium carbonate particles or kaolin particles, but the ink corresponding to the printing speed of a rotary ink jet printing machine can be absorbed only by the ink receiving layer. Absorbability may be insufficient. By providing an ink receiving layer containing calcium carbonate or kaolin on a surface size press base paper formed by size pressing with a size press liquid containing synthetic silica and a surface sizing agent, the ink receiving layer has good offset printing. Applicability can be obtained, and good ink absorptivity, printing density, suppression of printing unevenness, and excellent printing operability corresponding to a rotary inkjet printer can be obtained.

  In the ink receiving layer of the present invention, a conventionally known pigment can be used as a pigment other than the calcium carbonate or kaolin as long as the desired effect of the present invention is not impaired. Examples of such pigments include clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic silica, water Organic pigments such as aluminum oxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide and other inorganic pigments, styrene plastic pigments, acrylic plastic pigments, styrene-acrylic plastic pigments, polyethylene, microcapsules, urea resins, melamine resins And pigments.

  In the present invention, the ink receiving layer contains a conventionally known water-dispersible binder and / or water-soluble binder as a binder. Examples of the water dispersible binder include conjugated diene copolymer latex such as styrene-butadiene copolymer or acrylonitrile-butadiene copolymer, acrylate ester or methacrylate ester polymer, or methyl methacrylate-butadiene copolymer. Acrylic copolymer latex such as ethylene-vinyl acetate copolymer, vinyl copolymer latex such as vinyl chloride-vinyl acetate copolymer, polyurethane resin latex, alkyd resin latex, unsaturated polyester resin latex, or these Examples include, but are not limited to, a functional group-modified copolymer latex with a functional group-containing monomer such as a carboxyl group of these various copolymers, or a thermosetting synthetic resin such as a melamine resin and a urea resin. Examples of the water-soluble binder include starch derivatives such as etherified starch and phosphate esterified starch, cellulose derivatives such as methylcellulose, carboxymethylcellulose, and hydroxyethylcellulose, polyvinyl alcohol derivatives such as polyvinyl alcohol and silanol-modified polyvinyl alcohol, casein, and gelatin. Or modified products thereof, natural polymer resins such as soybean protein, pullulan, gum arabic, karaya gum, albumin or derivatives thereof, vinyl polymers such as polyacrylic acid soda, polyacrylamide, polyvinylpyrrolidone, sodium alginate, polyethyleneimine, polypropylene Examples include, but are not limited to, glycol, polyethylene glycol, maleic anhydride or a copolymer thereof. These water-dispersible binders and / or water-soluble binders can be used alone or in admixture of two or more.

  The total content of the binder in the ink receiving layer is preferably 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the total pigment in the ink receiving layer, from the viewpoint of the strength and ink absorbability of the ink receiving layer. Preferably they are 10 to 40 mass parts.

  In the present invention, as a method for coating the ink receiving layer on the surface-sized press base paper, a commonly used coating method can be used and is not particularly limited. For example, various coating apparatuses such as a blade coater, a roll coater, an air knife coater, a bar coater, a short dwell coater, and a curtain coater can be used.

  In the present invention, the total number of ink receiving layers provided on the surface-sized press base paper is not particularly limited, but is preferably one layer. In addition, a glossy expression layer having inorganic fine particles having an average particle diameter of 500 nm or less can be provided on the ink receiving layer as long as the desired effect of the present invention is not impaired. When the ink receiving layer is provided only on one side, it is possible to provide a coating layer for the purpose of curling correction or improving transportability on the opposite side.

The coating amount of the ink receiving layer is preferably determined based on the offset printability, the ink absorbability of the ink receiving layer, and the adhesive strength between the ink receiving layer and the size press base paper. Preferably specifically in the range coating weight of 3.0 g / ^{m 2} or more 20.0 g / ^{m 2} or less, 4.0 g / ^{m 2} or more 18.0 g / ^{m 2} or less in the range is more preferred. In the present invention, the coating amount of the ink receiving layer indicates the coating amount of the dry solid content.

  In the present invention, after the ink receiving layer is provided, it can be used as it is as a coated paper for a rotary inkjet printer, but if necessary, a machine calendar, a soft nip calendar, a super calendar, a multi-stage calendar, a multi-nip calendar, etc. Thus, the surface can be smoothed or gloss can be improved.

  However, mild calendering is preferred because excessive calendering for smoothing deteriorates ink absorbency in ink jet printing.

  Further, for the purpose of further increasing the glossiness, gloss can be applied using a known cast coating method.

  In the present invention, an ink receiving layer can be provided on both sides of a surface-sized press base paper in a rotary-type coated paper for an ink jet printer. Providing on both sides is preferable because printing can be performed on both sides depending on the printing machine.

  In the present invention, the ink receiving layer is formed on the surface-sized press base paper, but the ink receiving layer and the surface are adjusted as necessary for the adjustment of the adhesive strength between the layers and the ink absorbency within a range not impairing the desired effects of the present invention. An intermediate layer containing a pigment and a binder may be provided between the size press base papers. The pigment and binder used in the intermediate layer can be appropriately selected from pigments and binders that can be used in the ink receiving layer.

In the present invention, the basis weight of the rotary coated ink-jet printing paper is not particularly limited, but is preferably 40 g / m ² or more and 300 g / m ² or less.

  The coated paper for a rotary inkjet printer of the present invention may be particularly preferably used for a rotary inkjet printer having a printing speed of 120 m / min or more.

  Further, the coated paper for a rotary inkjet printer of the present invention can also be used for gravure printing, wet and dry electrophotography, and other printing methods. Furthermore, it can also be used for commercially available inkjet printers in addition to inkjet printers.

  According to another aspect of the present invention, there is provided a printing method using a rotary inkjet printer, the step of obtaining the above-mentioned rotary inkjet printer paper, and the ink of the rotary inkjet printer paper The method includes a step of forming a printed image on a receiving layer by performing rotary inkjet printing using a pigment ink at a printing speed of 120 m / min or more. By this printing method, it is possible to obtain a printed matter that is excellent in printing operability, excellent in ink absorbability and printing density, and suppressed in printing unevenness. Further, the present invention is a method for forming an excellent printed image, the step of obtaining a coated paper for a rotary inkjet printer, and an ink receiving layer of the coated paper for a rotary inkjet printer, The method includes a step of forming a printed image using an offset printing press and / or a rotary inkjet printing press. With this method of forming a printed image, an image can be formed with an offset printing and / or rotary inkjet printer, and the ink absorption and printing density are excellent in rotary inkjet printing, and uneven printing is suppressed. A printed image can be formed.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, “parts” shown in the examples represents a dry solid content or a mass part of a substantial component. The coating amount also indicates the coating amount of the dry solid content.

(Preparation of size press solution)
<Preparation of size press liquid 1>
After adding 100 parts of synthetic silica (Snowtex MP-1040, average particle size 0.1 μm, manufactured by Nissan Chemical Industries, Ltd.) to water, it was sufficiently dispersed using a disperser having a saw blade. Next, 15 parts of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) was added and mixed to obtain a size press solution 1.

<Preparation of size press liquid 2>
After adding 100 parts of synthetic silica (Silojet 733A, average particle size 0.3 μm, manufactured by Grace Devison) to water, it was sufficiently dispersed using a disperser having a saw blade. Next, 15 parts of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) was added and mixed to obtain a size press liquid 2.

<Preparation of size press solution 3>
After adding 100 parts of synthetic silica (nip gel AZ-204, average particle size of 2.7 μm, manufactured by Tosoh Silica Co.) to water, the mixture was dispersed using a dispersing machine having a saw blade. Next, 15 parts of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) was added and mixed to obtain a size press solution 3.

<Preparation of size press solution 4>
100 parts of synthetic silica (Mizukasil P-78A, average particle size 6 μm, manufactured by Mizusawa Chemical Co., Ltd.) was added to water, and then dispersed using a disperser having a saw blade. Next, 15 parts of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) was added and mixed to obtain a size press solution 4.

<Preparation of size press solution 5>
After adding 100 parts of synthetic silica (Mizukasil P-709, average particle diameter of 8 μm, manufactured by Mizusawa Chemical Co., Ltd.) to water, it was sufficiently dispersed using a disperser having a saw blade. Next, 15 parts of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) was added and mixed to obtain a size press solution 5.

<Preparation of size press liquid 6>
After adding 100 parts of calcium carbonate (Tama Pearl TP-121SA, average particle size 3.3 μm, manufactured by Okutama Kogyo Co., Ltd.) to water, it was sufficiently dispersed using a disperser having a saw blade. Next, 15 parts of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) was added and mixed to obtain a size press liquid 6.

<Preparation of size press solution 7>
After adding 100 parts of kaolin (HT, average particle size 3.5 μm, manufactured by Engelhard) to water, it was sufficiently dispersed using a disperser having a saw blade. Next, 15 parts of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) was added and mixed to obtain a size press solution 7.

<Preparation of size press liquid 8>
A size press solution 8 was obtained by adding and mixing 15 parts of polyvinyl alcohol (PVA105, manufactured by Kuraray Co., Ltd.) to water.

(Preparation of surface-sized press base paper)
<Preparation of surface-sized press base paper 1>
To a pulp slurry consisting of 100 parts of LBKP having a freeness of 400 mlcsf, 12 parts of light calcium carbonate as filler, 0.8 part of amphoteric starch, 0.8 part of sulfuric acid band, alkyl ketene dimer type sizing agent (Size Pine K903, Arakawa Chemical Industries, Ltd.) (Product made) Add 1.0 part, make paper with a long net paper machine, attach 2.5g / m ² of size press liquid 1 per side with an incline size press machine, machine calender treatment, basis weight 100g A surface-size press base paper 1 of / m ² was produced.

<Preparation of surface-sized press base paper 2>
The surface size press base paper 1 was obtained in the same manner as the surface size press base paper 1 except that the size press liquid 1 was changed to the size press liquid 2.

<Preparation of surface-sized press base paper 3>
The surface size press base paper 1 was obtained in the same manner as the surface size press base paper 1 except that the size press liquid 1 was changed to the size press liquid 3.

<Preparation of surface-sized press base paper 4>
The surface size press base paper 1 was obtained in the same manner as the surface size press base paper 1 except that the size press liquid 1 was changed to the size press liquid 4.

<Preparation of surface-sized press base paper 5>
The surface size press base paper 1 was obtained in the same manner as the surface size press base paper 1 except that the size press liquid 1 was changed to the size press liquid 5.

<Preparation of surface-sized press base paper 6>
In the surface size press base paper 1, the same procedure as in the surface size press base paper 1 was performed except that the size press liquid 1 was changed to the size press liquid 3 and the size press liquid 3 was adhered to 0.15 g / m ² per side. A size press base paper 6 was obtained.

<Preparation of surface-sized press base paper 7>
In the surface size press base paper 1, the surface press was performed in the same manner as the surface size press base paper 1 except that the size press liquid 1 was changed to the size press liquid 3 and the size press liquid 3 was adhered to 0.5 g / m ² per side. A size press base paper 7 was obtained.

<Preparation of surface-sized press base paper 8>
For surface size press base paper 1, the same procedure as for surface size press base paper 1 was performed except that size press liquid 1 was changed to size press liquid 3 and size press liquid 3 was adhered to 3.8 g / m ² per side. A size press base paper 8 was obtained.

<Preparation of surface-sized press base paper 9>
In the surface size press base paper 1, the surface press was performed in the same manner as the surface size press base paper 1 except that the size press liquid 1 was changed to the size press liquid 3 and the size press liquid 3 was adhered to 4.5 g / m ² per side. A size press base paper 9 was obtained.

<Preparation of surface-sized press base paper 10>
The surface size press base paper 1 was obtained in the same manner as the surface size press base paper 1 except that the size press liquid 1 was changed to the size press liquid 6.

<Preparation of surface-size press base paper 11>
Surface size press base paper 1 was obtained in the same manner as surface size press base paper 1 except that the size press liquid 1 was changed to the size press liquid 7 in the surface size press base paper 1.

<Preparation of surface-sized press base paper 12>
Surface size press base paper 1 was obtained in the same manner as surface size press base paper 1 except that size press liquid 1 was changed to size press liquid 8.

<Preparation of surface-size press base paper 13>
To a pulp slurry consisting of 100 parts of LBKP having a freeness of 400 mlcsf, 12 parts of light calcium carbonate as filler, 0.8 part of amphoteric starch, 0.8 part of sulfuric acid band, alkyl ketene dimer type sizing agent (Size Pine K903, Arakawa Chemical Industries, Ltd.) (Manufactured) 1.0 part is added, the paper is made with a long paper machine, and the size press solution 1 is adhered to 2.5 g / m ² per side with a film press machine, machine calendering is performed, and the basis weight is 100 g / m. ² surface-size press base paper 13 was produced.

<Preparation of surface-size press base paper 14>
The surface size press base paper 13 was obtained in the same manner as the surface size press base paper 13 except that the size press liquid 1 was changed to the size press liquid 3.

<Preparation of surface-sized press base paper 15>
The surface size press base paper 13 was obtained in the same manner as the surface size press base paper 13 except that the size press liquid 1 was changed to the size press liquid 5.

<Preparation of surface-size press base paper 16>
In the surface size press base paper 13, the surface press was performed in the same manner as the surface size press base paper 13 except that the size press liquid 1 was changed to the size press liquid 3 and the size press liquid 3 was adhered to 0.15 g / m ² per side. A size press base paper 16 was obtained.

<Preparation of surface-sized press base paper 17>
In the surface size press base paper 13, the size press liquid 1 was changed to the size press liquid 3, and the size press liquid 3 was applied in the same manner as the surface size press base paper 13 except that 4.5 g / m ² per side was adhered. A size press base paper 17 was obtained.

<Preparation of surface-sized press base paper 18>
The surface size press base paper 13 was obtained in the same manner as the surface size press base paper 13 except that the size press liquid 1 was changed to the size press liquid 6.

<Preparation of surface-sized press base paper 19>
The surface size press base paper 13 was obtained in the same manner as the surface size press base paper 13 except that the size press liquid 1 was changed to the size press liquid 7.

(Preparation of non-surface-sized press base paper)
<Preparation of non-surface-sized press base paper 20>
To a pulp slurry consisting of 100 parts of LBKP having a freeness of 400 mlcsf, 12 parts of light calcium carbonate as filler, 0.8 part of amphoteric starch, 0.8 part of sulfuric acid band, alkyl ketene dimer type sizing agent (Size Pine K903, Arakawa Chemical Industries, Ltd.) (Product made) 1.0 part was added, and papermaking was carried out with a long net paper machine. Subsequently, 2.5 g / m ² of size press liquid 3 was applied per side using a bar coater, and machine calendar processing was performed to prepare a non-surface-sized press base paper 20 having a basis weight of 100 g / m ² .

<Preparation of non-surface sized press base paper 21>
To a pulp slurry consisting of 100 parts of LBKP having a freeness of 400 mlcsf, 12 parts of light calcium carbonate as filler, 0.8 part of amphoteric starch, 0.8 part of sulfuric acid band, alkyl ketene dimer type sizing agent (Size Pine K903, Arakawa Chemical Industries, Ltd.) (Product made) 1.0 part was added, and papermaking was carried out with a long net paper machine. Subsequently, 2.5 g / m ² of size press liquid 3 was applied per side with a blade coater, and machine calendering was performed to prepare a non-surface-sized press base paper 21 having a basis weight of 100 g / m ² .

<Preparation of Non-Surface Size Press Base Paper 22>
To a pulp slurry consisting of 100 parts of LBKP having a freeness of 400 mlcsf, 12 parts of light calcium carbonate as filler, 0.8 part of amphoteric starch, 0.8 part of sulfuric acid band, alkyl ketene dimer type sizing agent (Size Pine K903, Arakawa Chemical Industries, Ltd.) (Product made) 1.0 part was added, and papermaking was carried out with a long net paper machine. Subsequently, the size press liquid 3 was applied at 2.5 g / m ² per side using an air knife coater, and machine calendar processing was performed to prepare a non-surface-sized press base paper 22 having a basis weight of 100 g / m ² .

<Preparation of ink receiving layer coating solution>
The ink receiving layer coating solution was prepared according to the following contents.
The number of pigment blended parts is described in Table 1. The binder number of blended parts is described in Table 1. The above-described contents were blended and mixed and dispersed with water.

  The pigments and binders abbreviated in Table 1 are as follows.

A: Calcium carbonate (Tama Pearl TP123, manufactured by Okutama Kogyo Co., Ltd.)
B: Kaolin (HG-90, manufactured by Huber)
C: Synthetic silica (Nipgel AZ-204, manufactured by Tosoh Silica)
D: Styrene-butadiene copolymer latex (JSR-2605G, manufactured by JSR)

  About Examples 1-20 and Comparative Examples 1-12, it produced with the following procedures.

<Preparation of coated paper>
An ink-receiving layer coating solution was coated on both sides of a surface-size press base paper or non-surface-size press base paper with a blade coater, dried, and then calendered to prepare a coated paper. The calender uses an apparatus composed of an elastic roll and a metal roll, and the nip linear pressure is within a range in which a thickness profile in the width direction can be appropriately obtained (80 kN / m) (Examples 1-3, 5-14, 16-20, Comparative Examples 1-4, 6-8, 10-12) and strong linear pressure (180 kN / m) (Examples 4 and 15). Further, the temperature of the metal roll was set to 40 ° C. for the weak linear pressure treatment and 180 ° C. for the strong linear pressure treatment. The calendar conditions are shown in Table 1.

  The coating amount of the ink receiving layer coating solution is shown in Table 1 as the coating amount per one side.

  In addition, the cross section of the coated paper obtained in Examples 1 to 20 and Comparative Example 12 was cut out with a cross section polisher, and the state was measured with a scanning electron microscope and elemental analysis with energy dispersion X between the raw raw paper and the ink receiving layer. Observed using line spectroscopy. In Examples 1 to 20 formed by size pressing with a size press liquid containing synthetic silica and a surface sizing agent, synthetic silica is more distributed in the recesses between the fibers of the raw paper than in Comparative Example 12. It was confirmed that the surface in contact with the ink receiving layer was smooth.

  About the coated paper of Examples 1-20 and Comparative Examples 1-12, the following methods evaluated offset printing suitability, and ink absorptivity, printing density, printing unevenness, and printing operability for a rotary inkjet printer. did.

  Except for the evaluation of the offset printing suitability, the evaluation was performed using a rotary inkjet printer. As a rotary ink jet printer, a printing press Truepress 520 manufactured by Dainippon Screen Mfg. Co., Ltd. was used. The ink used was dye ink for ink absorbency and printing density, and pigment ink was used for printing unevenness. Printing by the ink jet printer was performed at a printing conveyance speed of 128 m per minute.

(Evaluation of suitability for offset printing)
With an offset form rotary press made by Miyakoshi, printing speed: 150 m / min, ink used: T & K TOKA UV best cure ink and gold red, UV irradiation amount: 6000 m under the condition of 8 kW, and blank printing after printing The occurrence state and the state of the print sample were determined by visual evaluation according to the following five stages. If the evaluation is 3 to 5, there is no practical problem.
5: Extremely good.
4: Good.
3: Range in which there is no practical problem.
2: Defect.
1: Extremely bad.

(Evaluation of ink absorbency)
A total of 7 colors, including black, cyan, magenta, and yellow, and double colors (red, green, and blue) with three inks other than black ink on coated paper for rotary inkjet printers Solid printing was performed by a method in which a solid pattern was printed in 2 cm × 2 cm square in a horizontal row without gaps. The boundary part of each color solid part was determined by visual evaluation according to the following five stages. If the evaluation is 3 to 5, there is no practical problem.
5: There is no blur at the color boundary.
4: There is almost no bleeding at the boundary of the color.
3: Although the color boundary is blurred, the boundary can be clearly identified.
2: The color boundary is not clear, and the adjacent colors have moved slightly beyond the boundary.
1: The boundary of each color is not known, and bleeding to adjacent colors is large.

(Evaluation of printing density)
A total of 7 colors, including black, cyan, magenta, and yellow, and double colors (red, green, and blue) with three inks other than black ink on coated paper for rotary inkjet printers Solid printing was performed by a method in which a solid pattern was printed with 2 cm × 2 cm square in a horizontal row with no gaps. The print density of each color solid part was determined by visual evaluation according to the following five steps. If the evaluation is 3 to 5, there is no practical problem.
5: Vivid color and vivid colors.
4: There is no dullness in the color.
3: The color is slightly dull.
2: The color is very dull.
1: The color is very dull.

(Evaluation of uneven printing)
Double-colored (red, green, blue) with black, cyan, magenta, yellow single color and other three color inks except black ink on coated paper for rotary inkjet printers Solid printing was performed by a method of printing a total of 7 colors of solid patterns arranged in a horizontal row of 3 cm × 3 cm square. From the presence of partial shading color unevenness in each color solid part, printing unevenness was determined by visual evaluation in the following five stages. If the evaluation is 3 to 5, there is no practical problem.
5: Printing unevenness is not recognized.
4: Printing unevenness is slightly recognized depending on the color.
3: Print unevenness is slightly recognized.
2: Printing unevenness is partially recognized.
1: Printing unevenness is recognized in the entire printed portion.

(Evaluation of printing operability)
The occurrence of winding wrinkles during printing in a rotary inkjet printer was determined by visual evaluation according to the following five stages. If the evaluation is 3 to 5, there is no practical problem.
5: No waviness is observed on the coated paper, and no wrinkles are observed.
4: Slight waviness is observed in the coated paper, but no wrinkles are observed.
3: The coated paper is slightly wavy, but no wrinkles are observed.
2: Waves are slightly seen on the coated paper, and wrinkles are observed.
1: The coated paper is considerably wavy and wrinkles are always observed.

  The evaluation results of Examples 1 to 20 and Comparative Examples 1 to 12 are shown in Table 2.

  From Table 2, as shown in Examples 1 to 20, in the coated paper for a rotary type ink jet printer in which an ink receiving layer mainly composed of a pigment and a binder is provided on at least one surface of the base paper, the base paper is The coated paper, which is a surface size press base paper formed by size pressing with a size press liquid containing synthetic silica and a surface sizing agent, has good offset printing suitability and is suitable for a rotary inkjet printer. It is also found that the ink absorbability and the printing density are excellent, the printing unevenness in the printed portion is suppressed, and the printing operability is good. From Examples 11, 12, 19, and 20, it can be seen that it is more preferable to contain at least one calcium carbonate or kaolin as the pigment of the ink receiving layer. From the comparison between Examples 1 and 6 and Examples 2, 3 and 5, or the comparison between Examples 13 and 16 and Example 14, the average particle size of the synthetic silica is in the range of 0.3 μm or more and 7 μm or less. It turns out that it is preferable.

  On the other hand, from Table 2, the effects of the present invention cannot be obtained in Comparative Examples 1 to 12 that do not satisfy the conditions of the present invention.

Claims (3)

  In a coated paper for a rotary inkjet printing machine having an ink receiving layer mainly composed of a pigment and a binder on at least one surface of a base paper, the base paper is made of a size press liquid containing synthetic silica and a surface sizing agent. A coated paper for a rotary-type ink jet printer, which is a surface-size press base paper formed by size pressing.   The rotary coated ink jet printing paper according to claim 1, comprising at least one calcium carbonate or kaolin as a pigment for the ink receiving layer.   The coated paper for a rotary inkjet printer according to claim 1 or 2, wherein the synthetic silica has an average particle size in a range of 0.3 µm to 7 µm.