阅读说明：本技术 印刷用涂敷纸 (Coated paper for printing ) 是由 浦崎淳 名越应昇 高田秀树 于 2018-03-13 设计创作，主要内容包括：本发明可以提供一种印刷用涂敷纸,其具有原纸和位于上述原纸的至少单面的涂敷层,在上述涂敷层中,以原纸为基准位于最外侧的最外涂敷层至少含有高岭土、碳酸钙、淀粉类、乳液、分散剂、润滑剂和阳离子性树脂,在最外涂敷层中,相对于包含高岭土和碳酸钙的最外涂敷层中的颜料100质量份,淀粉类和乳液的合计为5质量份以上且13质量份以下,分散剂为0.02质量份以上且0.3质量份以下,润滑剂为0.25质量份以上且0.6质量份以下,而且阳离子性树脂为0.25质量份以上且0.5质量份以下,并且最外涂敷层中的高岭土与碳酸钙的含量质量比为高岭土：碳酸钙＝1：9～6：4,并且最外涂敷层中淀粉类与乳液的含量质量比为淀粉类：乳液＝1：9～4：6。根据本发明,可以提供具有耐印刷污染性、耐颜色浓度不均性和耐暗淡性的印刷用涂敷纸。(The present invention can provide a coated paper for printing, which has a base paper and a coating layer located on at least one surface of the base paper, wherein an outermost coating layer located outermost with respect to the base paper contains at least kaolin, calcium carbonate, a starch, an emulsion, a dispersant, a lubricant, and a cationic resin, wherein in the outermost coating layer, the total amount of the starch and the emulsion is 5 parts by mass or more and 13 parts by mass or less, the dispersant is 0.02 parts by mass or more and 0.3 parts by mass or less, the lubricant is 0.25 parts by mass or more and 0.6 parts by mass or less, and the cationic resin is 0.25 parts by mass or more and 0.5 parts by mass or less, with respect to 100 parts by mass of a pigment in the outermost coating layer containing kaolin and calcium carbonate, and wherein the content mass ratio of kaolin to calcium carbonate in the outermost coating layer is: calcium carbonate 1: 9-6: 4, the mass ratio of the starch to the emulsion in the outermost coating layer is starch: emulsion 1: 9-4: 6. according to the present invention, there can be provided a coated printing paper having resistance to printing stain, resistance to color unevenness in density, and resistance to darkness and lightness.)

1. A coated paper for printing, comprising a base paper and a coating layer located on at least one surface of the base paper, wherein an outermost coating layer located outermost with respect to the base paper contains at least kaolin, calcium carbonate, a starch, an emulsion, a dispersant, a lubricant, and a cationic resin, wherein in the outermost coating layer, the total of the starch and the emulsion is 5 parts by mass or more and 13 parts by mass or less, the dispersant is 0.02 parts by mass or more and 0.3 parts by mass or less, the lubricant is 0.25 parts by mass or more and 0.6 parts by mass or less, the cationic resin is 0.25 parts by mass or more and 0.5 parts by mass or less, and the content mass ratio of kaolin to calcium carbonate in the outermost coating layer is kaolin: calcium carbonate 1: 9-6: 4, the mass ratio of the starch to the emulsion in the outermost coating layer is starch: emulsion 1: 9-4: 6.

Technical Field

The present invention relates to a coated printing paper for use in an offset printing press, but printing can also be performed using an ink jet printing press.

Background

The inkjet recording system is a system in which droplets of ink are ejected from fine nozzles onto recording paper and are attached to the paper to form dots, thereby performing recording.

The inkjet recording system is used for small printers for home use and SOHO use, wide printers for making POPs or posters, and on-demand printers for producing commercial prints. The printing coated paper used has various glossy senses such as a glossy sense from matte. From the viewpoint of the cost of printed matter, the productivity of printed matter, and the method of handling printed matter, the quality required for printing coated paper used for producing commercial printed matter such as commercial documents, DM, books, pamphlets, leaflets, treatises, catalogs, and the like, and photographic paper developed in an inkjet recording system to replace silver halide photographs, is different.

As a low-cost, high-speed inkjet printing paper having high-speed inkjet printing adaptability and having offset printing adaptability and relief printing adaptability under normal commercial printing, there is known a coated paper for on-demand printing which is a coated paper for printing obtained by providing an ink-receiving layer on at least one side of a base paper and performing a calendering treatment, the base paper containing no internal sizing agent and no external sizing agent and containing an internal paper strength enhancer, the ink-receiving layer containing a pigment, a styrene-butadiene emulsion and a lubricant and further containing starch, 40% by mass or more of the pigment being calcium carbonate, and the coated paper for on-demand printing being used for high-speed inkjet printing using an aqueous ink, the coated paper for on-demand printing being 14.85 m/min or more in the case of a sheet paper and 20 m/min or more in the case of a roll paper (for example, see patent document 1).

For a plate (japanese: printing) printing machine such as an offset printing machine, a letterpress printing machine, or the like, a "plate" on which a printing image is formed is indispensable. On the other hand, on-demand presses do not require "plates". That is, the on-demand printer causes the image forming apparatus to directly print on paper in accordance with digital information relating to an image.

There are drop-on-demand printers using an ink jet recording system, i.e., ink jet printers. Examples of the ink jet printer include Truepressjet from SCREEN Graphic and Precision Solutions, MJP series from Miyakoshi, Prosper and VERSAMARK from Kodak, Jetpress from Fuji film, ColorInkjetWebPress from Hewlett-Packard, and the like.

Such an ink jet printer depends on various conditions of printing, but has a color printing speed as high as 10 to several tens of times, a printing speed of 15 m/min or more, and more than 100 m/min at higher speeds, as compared with small ink jet printers for home use and SOHO use, and wide ink jet printers. Therefore, the ink jet printer is different from a small ink jet printer facing home and SOHO and a wide ink jet printer.

Disclosure of Invention

Problems to be solved by the invention

With the spread of on-demand printing machines, printing coated papers are required to cope not only with a plate printing machine but also with an on-demand printing machine. In particular, there is a need for offset and inkjet printers that are more commonly used in the production of commercial prints.

In an offset printing press, ink adhering to a printing plate is transferred to a printing paper by contacting the ink with a blanket therebetween, thereby producing a printed matter. In the inkjet printer, ink droplets are ejected from fine nozzles that do not contact paper to produce a printed matter on a printing coated paper. Due to such a difference in printing system, the ink of the offset printing press has adhesiveness and a high concentration of the color material. The ink of the ink jet printer has fluidity and a low concentration of the color material.

When a conventional coated printing paper for an offset printing press is used in an inkjet printing press, the absorption of ink may not follow the printing speed, and printing stain may occur. In addition, color density unevenness (Japanese: color degree ム ラ) may occur in a single color printed portion. Further, the color of the printed portion may become dark, and the chroma may decrease. "color density unevenness" means: as the printing speed of the inkjet printer increases, ink absorption of the printing coated paper varies locally, and as a result, a phenomenon in which color shading is locally visible in a printed portion that should originally be formed in a single color. "chroma" is related to the vividness of a color. In general, physical elements constituting a color are "hue", "chroma", and "density", and the "chroma" as the vividness of the color and the "density" as the shade of the color are different elements.

We believe that they are due to the differences in printing methods and inks of offset and inkjet printers. The value of commercial prints is reduced by color density unevenness and reduction in chroma.

According to "application of paper coating-polymer emulsion" (published by the agency of the public society for high molecular products, 1992), a coating layer coating liquid for forming a coating layer of a coated paper for printing is basically composed of a pigment, an emulsion as a binder, and a water-soluble polymer, and further contains a dispersant, a lubricant, an antifoaming agent, a foam inhibitor, a preservative, a water-resistant additive, and the like as additives.

The types and contents of these materials have been studied in order to obtain the quality required for paper in accordance with a new printing method. However, the number of combinations thereof is close to infinite.

The present invention aims to provide a coated printing paper having the following quality for an ink jet printer in order to allow printing by the ink jet printer, although the coated printing paper has adaptability to an offset printer.

(1) Suppression of printing contamination (resistance to printing contamination)

(2) Color density unevenness of a single-color printed portion is suppressed (resistance to color density unevenness)

(3) The decrease in chroma of the printed portion was suppressed (resistance to darkness and lightness (Japanese: resistance to く す み))

Means for solving the problems

The present inventors have conducted intensive studies and, as a result, achieved the objects of the present invention by the following schemes.

A coated paper for printing, comprising a base paper and a coating layer located on at least one surface of the base paper, wherein an outermost coating layer located outermost with respect to the base paper contains at least kaolin, calcium carbonate, a starch, an emulsion, a dispersant, a lubricant, and a cationic resin, wherein in the outermost coating layer, the total of the starch and the emulsion is 5 parts by mass or more and 13 parts by mass or less, the dispersant is 0.02 parts by mass or more and 0.3 parts by mass or less, the lubricant is 0.25 parts by mass or more and 0.6 parts by mass or less, the cationic resin is 0.25 parts by mass or more and 0.5 parts by mass or less, and the content mass ratio of kaolin to calcium carbonate in the outermost coating layer is kaolin: calcium carbonate 1: 9-6: 4, the mass ratio of the starch to the emulsion in the outermost coating layer is starch: emulsion 1: 9-4: 6.

Effects of the invention

According to the present invention, there can be provided a coated printing paper having resistance to printing stain, resistance to color unevenness in density, and resistance to darkness and lightness.

Detailed Description

The present invention is described in detail below.

The coated printing paper of the present invention comprises a base paper and a coating layer on at least one surface of the base paper. The outermost coating layer located outermost with respect to the base paper contains at least kaolin and calcium carbonate as pigments, starches and emulsions as binders, dispersants, lubricants, and cationic resins.

In the present invention, "having a coating layer" means: a paper having a clear coating layer distinguishable from the base paper when the cross section of the paper is observed with an electron microscope. For example, if a resin component and a polymer component are coated, and the above-mentioned components are absorbed in a small amount by the base paper, and as a result, when the cross section of the printing paper is observed with an electron microscope, a clear layer distinguishable from the base paper is not present, this case does not belong to "having a coating layer".

The base paper is paper made by making paper stock such as Mechanical Pulp such as LBKP (Leaf Bleached Kraft Pulp), NBKP (Needle Bleached Kraft Pulp), wood chip Ground Pulp (GP), Thermal Mechanical Pulp (TMP), ChemiThermoMechanical Pulp (CTMP), chemical thermomechanical Pulp (ChemiThermoMechanical Pulp), CMP (ChemiThermoMechanical Pulp, ChemiMechanical Pulp), CGP (ChemiMechanical Pulp), and waste Pulp such as DIP (ChemiMechanical Pulp), and a polyvalent cationic salt, a polyvalent calcium carbonate, a light calcium carbonate, a heavy cationic salt, a polyvalent calcium carbonate, a heavy cationic salt, a light calcium carbonate, and a cationic salt such as calcium carbonate, a polyvalent calcium carbonate, and a cationic salt such as calcium carbonate, Paper-making reinforcing agent and other various additives. The base paper includes coated papers (japanese rice flour) obtained by subjecting paper to calendering, surface sizing with starch, polyvinyl alcohol, etc., or surface treatment, etc. Further, the base paper includes coated paper obtained by applying surface sizing treatment or surface treatment followed by calendering treatment.

The paper stock may contain one or more of a pigment dispersant, a thickener, a flowability improver, a defoaming agent, a foam inhibitor, a release agent, a foaming agent, a penetrant, a coloring dye, a coloring pigment, a fluorescent brightener, an ultraviolet absorber, an antioxidant, a preservative, an antifungal agent, a water resistant agent, a wet paper strength enhancer, a dry paper strength enhancer, and the like as other additives as appropriate within a range not to impair the desired effects of the present invention.

the coating layer can be provided on at least one surface of the base paper by coating and drying a coating liquid for the coating layer. The coating layer is 1 layer or more than 2 layers. Among the coating layers, the coating layer located outermost with respect to the base paper is referred to as the outermost coating layer. When the coating layer is 1 layer, the coating layer is the outermost coating layer. When the coating layer is 2 or more layers, the presence or absence and the type of each of the pigment, the binder and various additives are not particularly limited with respect to the coating layer present between the base paper and the outermost coating layer.

The coating amount of each coating layer is not particularly limited. The coating amount is preferably 5g/m per side based on the dry solid content²Above and 30g/m²Within the following ranges. When the coating layer is 2 or more layers, the total value is obtained. When the coating layer is 2 or more layers, the outermost coating layer preferably accounts for 70 mass% of the coating amount per one surface in terms of dry solid content.

The base paper may have a coating layer on one side or both sides. In the case of one side, the base paper may have a back coat layer known in the art on the side opposite to the side having the coating layer.

The method of providing the base paper with the coating layer is not particularly limited. For example, there may be mentioned: a method of coating and drying a coating layer coating liquid using a coating apparatus and a drying apparatus which are conventionally known in the papermaking field. Examples of the coating device include: comma coaters, film size press coaters, air knife coaters, rod coaters, knife coaters, gravure coaters, curtain coaters, micro gravure roll coaters (japanese: E バ ー コ ー タ ー), film transfer coaters, and the like. Examples of the drying device include: hot air dryers such as linear tunnel dryers, arch dryers, air circulation dryers, sinusoidal air flotation dryers, infrared heating dryers, dryers using microwaves, and the like.

The coating layer may be subjected to a calendering treatment.

The calendering treatment means: and (3) passing the paper between rollers to average the smoothness and thickness of the paper. Examples of the calendering apparatus include a mechanical calender, a soft nip calender, a supercalender, a multistage calender, and a multi-nip calender.

The coated printing paper of the present invention does not include a coated printing paper in which the outermost coating layer is cast (Japanese: キ ャ ス ト).

The outermost coating layer contains kaolin and calcium carbonate as pigments.

The content mass ratio of kaolin to calcium carbonate in the outermost coating layer is kaolin: calcium carbonate 1: 9-6: 4. from the viewpoint of printing suitability for an ink jet printer, the calcium carbonate is preferably ground calcium carbonate.

The outermost coating layer may contain a conventionally known pigment in addition to kaolin and calcium carbonate. Examples of conventionally known pigments include: inorganic pigments such as talc, satin white, lithopone, titanium oxide, zinc oxide, silica, alumina, aluminum hydroxide, zinc oxide, activated clay, and diatomaceous earth, and organic pigments such as plastic pigments. In the outermost coating layer, one or two or more of these pigments may be combined and used in combination with kaolin and calcium carbonate.

In the pigment of the outermost coating layer, the proportion of kaolin and calcium carbonate is preferably 80 mass% or more.

The outermost coating layer contains a starch and an emulsion as a binder.

The starches are: polysaccharides obtained by polymerizing glucose through glycosidic bonds; and polysaccharides obtained by variously modifying hydroxyl groups of glucose with substituent groups among polysaccharides obtained by polymerizing glucose through glycosidic bonds. Examples of starches include: esterified starches such as starch, oxidized starch, enzyme-modified starch, etherified starch, cationic starch, amphoteric starch, dialdehyde starch, phosphated starch and urea-phosphated starch (Japanese: Urea-Encapsulated エ ス テ ル - powder), hydroxyethylated starch, hydroxybutylated starch and the like. The starch is preferably urea phosphated starch.

Urea phosphated starch is starch having phosphate and carbamate groups on glucose. Examples of the method of introducing a phosphate group include a method of adding a phosphate such as sodium tripolyphosphate alone and performing a baking reaction, and examples of the method of introducing a phosphate group and a carbamate group include a method of adding urea together with inorganic phosphoric acids and performing a baking reaction. Urea-phosphated starches having various degrees of substitution with urea can be obtained mainly by the latter method of subjecting inorganic phosphoric acids and urea to a calcination reaction.

The average urea substitution degree of urea-phosphorylated starch is preferably 0.005 or more and 0.05 or less. The "urea substitution degree" refers to the substitution degree of a carbamate group in a hydroxyl group of a glucose unit constituting starch. For example, a urea degree of substitution of 0.02 means: there are 2 substituents per 100 glucose units constituting the starch. The urea substitution degree is a value known in the past for starch, and can be determined by a known method. For example, the nitrogen content can be determined from the nitrogen content obtained by using a thermal decomposition GC method or a CHN elemental analyzer. Further, reference is made to the "starch science laboratory" journal of the ethnic group of Suzuki Linnakai, Zhongcun, and 1 st release in 1979, and release to bookstores.

In the present invention, an emulsion (Japanese: ラ テ ッ ク ス) refers to a resin of a polymer stably dispersible in water. Examples of emulsions include: as conventionally known water-dispersible binders, there are known a conjugated diene resin such as a styrene-butadiene copolymer or an acrylonitrile-butadiene copolymer, an acrylic resin such as a polymer of an acrylic acid ester or a methacrylic acid ester or a methyl methacrylate-butadiene copolymer, a vinyl resin such as an ethylene-vinyl acetate copolymer or a vinyl chloride-vinyl acetate copolymer, a functional group-modified resin obtained from a monomer having a functional group such as a carboxyl group of a urethane resin, an alkyd resin, an unsaturated polyester resin or the above-mentioned various copolymers, a heat-curable synthetic resin such as a melamine resin or a urea resin, a natural rubber, and the like. The emulsion is preferably a styrene-butadiene copolymer resin.

The mass ratio of the starches to the emulsion in the outermost coating layer was, in terms of dry solid content, starch: emulsion 1: 9-4: 6.

The outermost coating layer may contain a conventionally known binder in addition to the starch and the emulsion. Examples of binders include: cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, natural polymer resins such as casein, gelatin and soybean protein or derivatives thereof, polyvinyl pyrrolidone, polyvinyl alcohol and various modified polyvinyl alcohols thereof, polypropylene glycol and polyethylene glycol. One or more kinds selected from these binders may be contained in the outermost coating layer in combination with the starches and the emulsion.

In the outermost coating layer, the starch and the emulsion are preferably contained in the binder of the outermost coating layer by 80 mass% or more. In the outermost coating layer, the total content of the starch and the emulsion is 5 parts by mass or more and 13 parts by mass or less with respect to 100 parts by mass of the pigment in the outermost coating layer containing kaolin and calcium carbonate.

The outermost coating layer contains a dispersant. The dispersant is a material for dispersing a water-insoluble substance such as a pigment in an aqueous solution, and is a conventionally known dispersant. Examples of conventionally known dispersants include: polycarboxylic acid resins such as sodium polycarboxylate, acrylic resins such as sodium polyacrylate, styrene-acrylic resins, isobutylene-maleic acid resins, sulfonated polystyrene resins, polyvinyl alcohol, modified polyvinyl alcohol, condensed phosphates, and the like. The outermost coating layer may contain one or two or more kinds selected from these dispersants.

The dispersant of the outermost coating layer is preferably one or two or more selected from polycarboxylic acid-based resins and acrylic resins.

The content of the dispersant in the outermost coating layer is 0.02 parts by mass or more and 0.3 parts by mass or less per one surface with respect to 100 parts by mass of the pigment in the outermost coating layer containing kaolin and calcium carbonate. Materials that duplicate the binder are present in the dispersant. However, the material used as the dispersant is clearly less in the outermost coating layer than the binder, and the dispersant has a smaller molecular weight than the binder, so that it can be distinguished. The pigment can be dispersed by the presence of the binder, but the color density unevenness resistance can be improved by including the dispersant in the outermost coating layer.

The outermost coating layer contains a lubricant. The lubricant is a conventionally known lubricant. Examples of conventionally known lubricants include: higher fatty acid salts, waxes, organosilicon compounds, and the like. Examples of the higher fatty acid salt include: higher fatty acid metal salts (for example, sodium salt, potassium salt, zinc salt, and calcium salt thereof) such as laurate, oleate, palmitate, stearate, and myristate, or higher fatty acid ammonium salts such as ammonium laurate, ammonium oleate, ammonium palmitate, ammonium stearate, and ammonium myristate. Examples of the waxes include: aliphatic hydrocarbons and derivatives thereof such as vegetable waxes, animal waxes, montan waxes, paraffin waxes, synthetic waxes (hydrocarbon-based synthetic waxes, polyethylene emulsion-based waxes, higher fatty acid esters, fatty acid amides, ketone amines, hydrogenated oils, etc.), polypropylene, polytetrafluoroethylene polymers, and the like. Examples of the organosilicon compound include: polyalkylsiloxane and its derivatives, dimethyl silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil, alkyl/aralkyl-modified silicone oil, amino-modified silicone oil, polyether-modified silicone oil, higher fatty acid-modified silicone oil, carboxyl-modified silicone oil, fluorine-modified silicone oil, epoxy-modified silicone oil, and the like. The outermost coating layer may contain one or two or more kinds selected from these lubricants.

The lubricant of the outermost coating layer is preferably a higher fatty acid salt.

The content of the lubricant in the outermost coating layer is 0.25 parts by mass or more and 0.6 parts by mass or less per one surface with respect to 100 parts by mass of the pigment in the outermost coating layer containing kaolin and calcium carbonate.

The outermost coating layer contains a cationic resin. The cationic resin is a conventionally known cationic resin. The preferred cationic resin is a polymer or oligomer containing a primary to tertiary amine or quaternary ammonium salt in which protons are easily coordinated and dissociated when dissolved in water to be cationic. Further, the preferred cationic resin is a low cationic resin having a cationization degree of more than 0meq/g and not more than 3meq/g or a high cationic resin having a cationization degree of more than 3 meq/g. Here, the cationization degree is a value measured by a colloid titration method.

Examples of conventionally known cationic resins include: polyethyleneimine, polyamine and modified polyamine, polyvinylpyridine, polyamidoamine, polyvinylamine, modified polyamide, polyacrylamide, polyallylamine, polydialkylaminoethyl polymethacrylate, polydialkylaminoethyl polyacrylate, polydialkylaminoethylmethacrylamide, polydialkylaminoethylacrylamide, polyvinylbenzyltrimethylammonium chloride, polydiallyldimethylammonium chloride, a copolymer of allyldimethylammonium chloride and acrylamide, a polycondensate of an aliphatic monoamine and an epihalohydrin compound such as a dimethylamine-epichlorohydrin polycondensate, or a polycondensate of an aliphatic polyamine and an epihalohydrin compound such as a diethylenetriamine-epichlorohydrin polycondensate, polyamine polyamide epichlorohydrin, a dicyandiamide-formaldehyde polycondensate, a dicyandiamide diethylenetriamine polycondensate, a polyepoxy amine, a polyamide-epoxy resin, melamine resin, and urea resin. The outermost coating layer may contain one or two or more kinds selected from these cationic resins. The average molecular weight of the cationic resin is not particularly limited. The average molecular weight is preferably 500 or more and 100000 or less, more preferably 1000 or more and 60000 or less.

The cationic resin of the outermost coating layer is preferably a modified polyamine or a modified polyamide.

The content of the cationic resin in the outermost coating layer is 0.25 parts by mass or more and 0.5 parts by mass or less per surface with respect to 100 parts by mass of the pigment in the outermost coating layer containing kaolin and calcium carbonate.

the coated paper for printing of the present invention contains kaolin and calcium carbonate as pigments in the outermost coating layer, and the total content of starches and emulsions and the mass ratio of the contents, the content of the dispersant, the content of the lubricant, and the content of the cationic resin are within specific ranges with respect to 100 parts by mass of the pigment in the outermost coating layer containing kaolin and calcium carbonate, whereby printing stain resistance, color density unevenness resistance, and dullness resistance can be obtained. If any of the above-mentioned ranges is not satisfied, any of the resistance to printing stain, the resistance to color unevenness in density, and the resistance to darkness and lightness cannot be obtained with the printing coated paper.

The outermost coating layer may further contain, as necessary, various additives conventionally known in the art of coated paper. Examples of the additives include tackifiers, flowability improvers, defoaming agents, foaming agents, penetrants, coloring pigments, coloring dyes, fluorescent brighteners, ultraviolet absorbers, antioxidants, preservatives, and mildewcides.