JP2013170331A - Newsprint paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide newsprint paper by which print-through is prevented, which is excellent in folding processability, has a sufficient firmness as newsprint paper, has off-set printability, and is suitable for a newsprint paper printing apparatus provided with an inkjet printing system.SOLUTION: The newsprint paper has base paper and a coating layer. The newsprint paper has a basis weight of 55 g/mor less, and includes a black-colored pigment in an amount ranging from 50 ppm to 200 ppm with respect to the basis weight of the newsprint paper, a coating layer on each of the surfaces in a coating amount ranging from 20 mass% to 30 mass% with respect to the basis weight of the newsprint paper, and the coating layer includes a water soluble multivalent cation salt and a cationic resin.

Description

  The present invention relates to newsprint. Specifically, the present invention relates to newspaper printing suitable for a newspaper printing apparatus having an ink jet recording system.

  Ink jet recording systems have been increased in speed and size, and in the field of newspaper printing, newspaper printing apparatuses having an ink jet recording system for dealing with plateless printing and on-demand printing have been disclosed (see, for example, Patent Documents 1 and 2). .

  As a paper corresponding to the ink jet recording system, an ink jet recording medium or an ink jet receiving sheet for proof printing of newspaper printing and printing sample preparation is disclosed (for example, see Patent Documents 3 and 4). These are not newspaper printing apparatuses, but are inkjet recording media or inkjet receiving sheets used in household or SOHO inkjet printers. In other words, it is a dedicated paper for inkjet printers in which the hue of the paper is similar to that of newsprint.

  Inkjet-compatible newspaper for offset printing, which is excellent in ink-jet printability, is disclosed for an offset newspaper rotary press provided with a system for printing variable information by an ink jet system on a part of the offset newspaper press (for example, patent document) 5). This ink-jet offset newsprint paper is a non-coated paper type paper that contains specific pulp as the raw paper pulp material, contains white carbon as a filler, is made without paper with a sizing agent, and has a surface size. This paper is sized with an agent.

JP 2008-97373 A JP 2011-157168 A JP 2000-318299 A JP 2002-225426 A JP 2011-161720 A

  Ink used in the ink jet recording system has a low color material concentration and contains a large amount of ink solvent. Particularly in color printing, more ink solvent is supplied to the paper. Therefore, newsprint with a small basis weight of the paper has a problem that the ink can be seen through.

  In the field of newspaper printing, colorization is progressing and the demand for image quality is increasing. The newspaper for offset printing for ink-jet printing as described in Patent Document 5 has improved image bleeding and opacity after printing as an uncoated paper type, but further improvement in image quality is desired. . In terms of suppression of ink back-through and image quality, it is effective to have a coating layer on the base paper in order to accept ink of the ink jet recording method. However, although the suitability for the inkjet recording system is improved by the coating layer, blanket piling or the like is expected to occur in the offset printing type newspaper printing apparatus, and the offset printing suitability becomes a problem.

  The peculiar quality of newsprint includes waist and folding processing suitability. The newspaper is folded small for convenience of delivery. When you open a newspaper and hold it in your hand, you need a certain amount of waist on the paper. In the case of having a coating layer, in a newspaper paper having a small basis weight, the basis weight of the base paper becomes relatively smaller by the amount having the coating layer, and the stiffness of the paper is lowered. At the same time, problems such as sky folding tend to occur in the newspaper folding process. As for the sky folding, for example, as described in Japanese Patent No. 4227925, various devices on the device side have been conventionally performed. However, it is desired to improve the folding processability of newsprint paper that is not easily folded.

  Accordingly, an object of the present invention is to provide a newspaper printing apparatus in which the back-through of the ink is suppressed, has excellent folding processing suitability, has sufficient waist as newspaper paper, has offset printing suitability, and has an inkjet recording system. To provide a suitable newspaper.

As a result of intensive research, the inventors have a newsprint having a base paper and a coating layer, and the newsprint has a black color pigment in a range of 50 ppm to 200 ppm with respect to the basis weight of the newsprint, A basis weight having a coating layer on both sides in a coating amount range of 20% by mass to 30% by mass with respect to the basis weight of newsprint, and the coating layer having a water-soluble polyvalent cation salt and a cationic resin. The inventors have invented newsprint with an amount of 55 g / m ² or less.

  Preferably, the water-soluble polyvalent cation salt is calcium chloride or calcium nitrate.

  As another aspect of the present invention, there is provided a printing method using a newspaper printing apparatus equipped with an ink jet recording method, the step of obtaining the newsprint paper, and a printing speed of 15 m / min or more by the ink jet recording method on the coated layer of the newsprint paper. A printing method including a step of forming a printed image is provided. The present invention is also a method for forming an excellent printed image, using a newspaper printing apparatus provided with the above-mentioned newsprint, and an offset printing method and / or an ink jet recording method on a coating layer of the newsprint. A method of forming a printed image including a printing step is provided.

  According to the present invention, there is provided newsprint paper that is suppressed in ink penetration, excellent in folding workability, has sufficient waist as newsprint paper, has offset printing suitability, and is suitable for a newsprint apparatus equipped with an ink jet recording system. be able to.

  Hereinafter, the present invention will be described in detail.

  The newsprint of the present invention has a base paper and a coating layer. Base paper includes chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, PGW, RMP, TMP, CTMP, CMP and CGP, and waste paper pulp such as DIP, plus fillers such as calcium carbonate, sizing agent, yield Agents, cationic compounds, pigment dispersants, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, colored dyes, colored pigments, fluorescent whitening agents, UV absorption Additives, antioxidants, preservatives, antibacterial agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers, etc. Paper made under certain conditions.

  In the present invention, the sizing degree of the base paper may be any sizing degree as long as the desired effect of the present invention is not impaired. The degree of sizing can be adjusted by the amount of the internally added sizing agent and the coating amount of the surface sizing agent applied to the base paper. Examples of the internally added sizing agent include rosin sizing agents, alkenyl succinic anhydrides, alkyl ketene dimers, neutral rosin sizing agents, and cationic styrene-acrylic sizing agents. Examples of the surface sizing agent include a styrene-acrylic sizing agent, an olefin sizing agent, and a styrene-maleic sizing agent.

  In the present invention, the base paper can be subjected to a size press with a size press liquid containing a surface sizing agent. 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.

  In the present invention, the coating layer is formed by coating on the base paper. However, the base paper may be pre-calendered or coated on the base paper as necessary for the purpose of adjusting smoothness. An undercoat layer may be provided between the working layer and the base paper.

In the present invention, the base paper preferably has a basis weight of 37 g / m ² or more and 44 g / m ² or less from the viewpoint of newspaper use.

In the present invention, the basis weight of the newsprint is 55 g / m ² or less from the viewpoint of newspaper use.
In this invention, a coating layer is a coating amount range of 20 mass%-30 mass% with respect to the basic weight of newsprint. The range of the coating amount is mass% of the entire coating layer including both sides with respect to the basis weight of the newsprint. For example, the basis weight of newsprint is coated amount of the entire coating layer When it is 40 g / ^{m 2} is in the range of ^{8g / m 2 ~12g / m 2} . The coating amount used in the present invention refers to the dry solid content. When the coating amount is less than 20% by mass with respect to the basis weight of the newsprint paper, ink breakthrough or deterioration in image quality is recognized in a newsprint printing apparatus equipped with an ink jet recording method. When the coating weight is more than 30% by weight with respect to the basis weight of the newsprint, the lowering of the newsprint or the suitability of the newsprint can be recognized due to the weight and thickness of the coating layer. Become.

In the present invention, the newsprint has a black color pigment. The black color pigment has a content range of 50 ppm to 200 ppm (parts per million) based on the basis weight of newsprint. For example, the basis weight of newsprint content is the black coloring pigment in 40 g / ^{m 2} is in the range of ^{0.002g / m 2 ~0.008g / m 2} . When the content is less than 50 ppm with respect to the basis weight of the newspaper, ink breakthrough is recognized in the newspaper printing apparatus equipped with the ink jet recording method. When the content exceeds 200 ppm with respect to the basis weight of the newsprint, the image quality is degraded in terms of color printing hue or contrast. Even if the content of the black color pigment is in the above range, the effect of suppressing the ink see-through cannot be obtained unless the coating layer has 20% by mass or more based on the basis weight of the newspaper. For paper with a small basis weight compared to a newspaper printing apparatus equipped with an ink jet recording method, the ink colorant is retained in the coating layer and the opacity of the paper is increased by the black color pigment, thereby improving the ink through-through effect. And you can get picture quality. Further, the black colored dye is not preferable because it may reduce the absorbability of the ink of the ink jet recording method.

  In the present invention, the black color pigment may be present in either the base paper or the coating layer, or in both.

  In the present invention, the black coloring pigment includes, for example, furnace black, lamp black, acetylene black, carbon black such as channel carbon and thermal black, magnetic fine particles such as magnetite and ferrite, aniline black, titanium black, copper oxide, Known black coloring pigments such as iron oxide and phthalocyanine black can be listed. From the viewpoint of the effects of the present invention, carbon blacks are preferred. Black colored pigments are commercially available from, for example, Dainichi Seika Kogyo Co., Ltd., Sumika Chemtex Co., Ltd., Gokoku Color Co., Ltd.

  In the present invention, the coating layer of newsprint has a water-soluble polyvalent cation salt and a cationic resin. Ink used in the ink jet recording method includes dye ink in which a color material is dissolved in an ink solvent and pigment ink in which a color material is dispersed in an ink solvent. The paper is required to cope with such differences in color materials. By having a water-soluble polyvalent cation salt and a cationic resin, in a newspaper printing apparatus equipped with an ink jet recording system, any of the dye ink and pigment ink can suppress the back-through of ink and can have image quality without bleeding or feathering. can get. Even if the coating amount of the coating layer is in the above range and the content of the black color pigment is in the above range with respect to the basis weight of the newsprint, the water-soluble polyvalent cation salt or the cationic resin is used. If the coating layer does not exist, it is not possible to obtain an image quality that suppresses ink penetration and does not cause bleeding or feathering.

  In the present invention, the water-soluble polyvalent cation salt is a salt containing a polyvalent cation that can be dissolved in water at 20 ° C. in an amount of 1% by mass or more. Examples of the polyvalent cation include divalent cations such as magnesium, calcium, strontium, barium, nickel, zinc, copper, iron, cobalt, tin and manganese, trivalent cations such as aluminum, iron and chromium, or Tetravalent cations such as titanium and zirconium, and complex ions thereof. The anion that forms a salt with the polyvalent cation may be either an inorganic acid or an organic acid, and is not particularly limited. Inorganic acids include, but are not limited to, hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, hydrofluoric acid, and the like. Examples of organic acids include, but are not limited to, formic acid, acetic acid, lactic acid, citric acid, oxalic acid, succinic acid, and organic sulfonic acid. As the water-soluble polyvalent cation salt, calcium salts such as calcium chloride, calcium formate, calcium nitrate, and calcium acetate are preferable. Furthermore, when the ink used in the ink jet recording method is a pigment ink, calcium chloride or calcium nitrate is preferable from the viewpoint of image quality such as no image smear due to poor fixability of the pigment ink.

  In the present invention, the cationic resin is a commonly used cationic polymer or cationic oligomer, and protons are easily coordinated, and are first to third grades that dissociate and exhibit cationic properties when dissolved in water. Polymers or oligomers containing amines or quaternary ammonium salts. For example, polyethyleneimine, polyvinyl pyridine, polyamine sulfone, polydialkylaminoethyl methacrylate, polydialkylaminoethyl acrylate, polydialkylaminoethyl methacrylamide, polydialkylaminoethyl acrylamide, polyepoxyamine, polyamidoamine, dicyandiamide-formalin condensate, polyvinyl Compounds such as amines and polyallylamines and their hydrochlorides, polydiallyldimethylammonium chloride and copolymers of diallyldimethylammonium chloride and acrylamide, polydiallylmethylamine hydrochloride, dimethylamine-epichlorohydrin condensates, etc. However, it is not limited to these. As the cationic resin, when the ink used in the ink jet recording method is a dye ink, a dimethylamine-epichlorohydrin condensate is preferable from the viewpoint of image quality such as no dye ink bleeding or feathering. In the present invention, the average molecular weight of the cationic resin is preferably in the range of 500 to 20,000, more preferably in the range of 1,000 to 10,000.

  In the present invention, the coating layer preferably contains a pigment and a binder. The pigment used in the present invention is a conventionally known pigment. For example, calcium carbonate, kaolin, 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 amorphous silica, Colloidal silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide and other inorganic pigments, styrene plastic pigment, acrylic plastic pigment, styrene-acrylic plastic pigment, polyethylene, microcapsule, urea resin, melamine Examples thereof include organic pigments such as resins. From the viewpoint of offset printing suitability, calcium carbonate is preferable.

  The binder used in the present invention is a conventionally known water-dispersible binder and water-soluble 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 And a functional group-modified copolymer latex with a functional group-containing monomer such as a carboxyl group of these 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 oxidized starch, 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, gelatin or modified products thereof, soy protein, pullulan, gum arabic, karaya gum, albumin and other natural polymer resins or derivatives thereof, vinyl polymer such as sodium polyacrylate, sodium alginate, polypropylene glycol, polyethylene glycol, anhydrous Maleic acid or a copolymer thereof may be used.

  In the present invention, the method for coating the coating layer is a conventionally known coating method. Examples thereof include various blade coaters such as an air knife coater and a rod blade coater, a roll coater, a bar coater, a curtain coater, and a short dwell coater. Preferred are various blade coaters or film transfer coaters suitable for high-speed productivity, and particularly preferred is a film transfer coater.

  In the present invention, the newsprint can be used with the coating layer applied and dried, but if necessary, a machine calendar, soft nip calendar, super calendar, multi-stage calendar, multi-nip calendar, etc. were used. The surface can also be smoothed by calendaring. However, if an excessive calendar process is performed for smoothing, the ability to accept ink of the ink jet recording system is lowered, and therefore an appropriate calendar process is preferable.

  In the present invention, coating layers are provided on both sides of the base paper for newspaper use.

  By using the newsprint according to the present invention in a newsprint printing apparatus equipped with an ink jet recording method having a printing speed of 15 m / min or more, a printing method capable of forming a good image is obtained. In addition, by printing the newspaper according to the present invention with a newspaper printing apparatus having an offset printing method and / or an ink jet recording method, printing capable of obtaining good image quality in both the offset printing method and the ink jet recording method. This is an image forming method.

  The newsprint of the present invention can be used in gravure printing methods, other printing methods such as wet and dry electrophotographic methods, and ink jet printers.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Moreover, “parts” and “%” shown in the examples indicate dry solids or mass parts and mass% of substantial components. The coating amount indicates the dry solid content.

(Preparation of base paper)
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 sulfate band, alkyl ketene dimer type sizing agent (Size Pine K903, Arakawa Chemical Industries, Ltd.) 1.0 parts, black colored pigment (carbon black with an average primary particle size of D 0.2 μm, TB-510 BLACK TR, manufactured by Dainichi Seika Kogyo Co., Ltd.) in the number of parts shown in Table 1, The paper is made with a size press machine and 3.0 g / m ^{2 of} oxidized starch is adhered per both sides, machine calendered, and a basis weight of 41 g / m ² , basis weight of 37 g / m ² , basis weight of 34 g / m ² . Each base paper was prepared. Table 1 shows the basis weight of the base paper used in each Example and each Comparative Example and the number of blended parts of the black color pigment.

<Preparation of coating solution for coating layer>
The coating solution for the coating layer was prepared according to the following contents.
Heavy calcium carbonate 50 parts Light calcium carbonate 50 parts Polyvinyl alcohol 10 parts Phosphate esterified starch 10 parts Water-soluble polyvalent cation salt Types and parts are listed in Table 1 Cationic resin (dimethylamine-epichlorohydrin polycondensate, jet Fix 5052, manufactured by Satoda Chemical Co., Ltd.) The number of copies is described in Table 1. Black colored pigment (carbon black with an average primary particle size D of 0.2 μm, TB-510 BLACK TR, manufactured by Dainichi Seika Kogyo Co., Ltd.) The number of copies is described in Table 1. It mix | blended by the content, and mixed and dispersed with water, and it adjusted to solid content concentration 40%.

  About Examples 1-17 and Comparative Examples 1-11, it produced with the following procedures.

<Production of newsprint>
On the base paper, the coating solution of the coating layer was coated and dried on both sides using a film transfer coater so that the coating amount was the same as the front and back sides. After drying, calendering was performed to produce newsprint. The calendering was performed using a device composed of an elastic roll and a metal roll, and the nip linear pressure was set at a linear pressure of 80 kN / m within a range in which a thickness profile in the width direction was appropriately obtained. The temperature of the metal roll was 40 ° C. In each Example or each Comparative Example, Table 1 shows the coating amount per both sides and the used base paper.

  Each item was evaluated according to the following method for the newspapers of Examples and Comparative Examples described in Table 1. The results are shown in Table 1.

<Evaluation of suitability for offset printing>
With an offset form rotary press manufactured by Miyakoshi Co., Ltd., printing speed: 150 m / min, ink used: T & K TOKA UV best cure ink and gold red, UV irradiation amount: 8,000 m under the condition of 8 kW, and blanket piling The state of occurrence and the state of the print sample were determined by visual evaluation. The evaluation criteria followed the following indicators. If the evaluation is 3 to 5, there is no practical problem.
5: Blanket piling does not occur at all and the characteristics are good.
4: Slight blanket piling occurs, but the characteristics are generally good.
3: Blanket piling occurs, but there is no practical problem.
2: The occurrence of blanket piling is conspicuous and there are practical problems.
1: Blanket piling is severe and the characteristics are poor.

<Evaluation of ink breakthrough>
An evaluation image was printed at 75 m / min using a pigment ink using an inkjet printer Jet Leader manufactured by Tokyo Kikai Seisakusho. The degree of ink that printed 18 cm × 18 cm solid pattern with black ink and printed on the back surface was visually evaluated. If the evaluation is 3 to 5, there is no practical problem.
5: No show-through is observed.
4: Slight penetration is recognized.
3: Slightly see-through is observed, but is a practically acceptable level.
2: Some show-through is observed.
1: Remarkable penetration is observed.

<Evaluation of image quality of inkjet recording>
An evaluation image was printed at 75 m / min using a pigment ink using an inkjet printer Jet Leader manufactured by Tokyo Kikai Seisakusho. Moreover, the evaluation image was printed at 150 m / min using dye ink using the Miyakoshi ink jet printer NewMJP-600 (model | form: MJP-20C). The evaluation images were black, cyan, magenta, yellow, solid images of each single color, and images composed of 50% halftone dot patterns and characters. The image quality of the print samples was evaluated in the following five stages from a comprehensive viewpoint such as image contrast, feathering, and image smearing. 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 folding processability>
Using an inkjet printer Jet Leader manufactured by Tokyo Kikai Seisakusho, newspaper paper after printing was folded and the state of sky folding was determined. If the evaluation is 3, there is no practical problem.
3: No occurrence of sky breaks is observed.
2: Severe breakage is observed.
1: Occurrence of sky folds is observed.

<Evaluation of waist of paper>
Using an inkjet printer manufactured by Tokyo Kikai Seisakusho, an evaluation character is printed at 75 m / min using pigment ink, and the newspapers of each Example and each Comparative Example are processed into newspaper size, folded into five, and folded in two. A newspaper sample was used. When the newspaper sample was read and held in the hand, it was sensory-evaluated by the five testers in the following five stages, and the average value of the five persons (rounded off the decimal point) was used as the final evaluation. If the evaluation is 3 or 4, there is no practical problem.
4: Good without falling down.
3: Slightly easy to fall, but acceptable level.
2: The paper tends to fall down and is slightly defective.
1: The paper falls and is defective.

  From the results shown in Table 1, Examples 1 to 17 according to the present invention have offset printing suitability, and ink back-through is suppressed even in the ink jet recording system. It can be seen that From the comparison between Examples 9 and 15 and Example 16 or Example 17, it can be seen that the water-soluble polyvalent cation salt is preferably calcium chloride or calcium nitrate in terms of image quality. On the other hand, the ratio of the coating amount of the coating layer to the basis weight of the newsprint does not correspond to the range according to the present invention. In Comparative Examples 5 to 7 not corresponding to the range according to the invention and Comparative Examples 8 to 11 in which the coating layer does not have a water-soluble polyvalent cation salt or a cationic resin, all of the effects according to the present invention can be satisfied. I understand that I can't.

Claims (2)

Newspaper paper having a base paper and a coating layer, wherein the newsprint paper has a black color pigment in a range of 50 ppm to 200 ppm with respect to the basis weight of the newsprint paper, and is from 20% by mass to the basis weight of the newsprint paper Newspaper paper having a basis weight of 55 g / m ² or less, having a coating layer on both sides within a coating weight range of 30% by mass, and the coating layer having a water-soluble polyvalent cation salt and a cationic resin.   The newsprint according to claim 1, wherein the water-soluble polyvalent cation salt is calcium chloride or calcium nitrate.