JP2009228170A - Coated base paper for printing, and method for producing the coated base paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing coated base paper for printing using a gap former papermaking machine, which provides a high dewatering effect of paper stock to give the coated paper having sufficiently high interlaminar strength and good formation. <P>SOLUTION: There is provided the method for producing coated base paper for printing using a gap former papermaking machine of roll-and-blade former design having a dewatering mechanism using a dewatering blade just after initial dewatering by a forming roll, at a papermaking speed of 1,300 m/min or higher by acid-free paper making method. In the method, as a paper-strengthening agent, 0.10-0.30 wt.% of a cationized starch and 0.10-0.60 wt.% of a synthetic paper-strengthening agent, each based on paper stock pulp, are added to the paper stock pulp. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printing base paper for printing and a method for producing a coated paper. In particular, the present invention relates to a coated base paper manufactured at high speed by a neutral paper making method using a gap former type paper machine, a coated paper obtained from the coated base paper, and a manufacturing method thereof.

  In recent years, the improvement and development of paper machines are progressing, and the tendency of speeding up and widening of paper machines is remarkable due to high productivity. As for paper coating machines, on-machine coaters that can consistently perform papermaking and coating have become widespread.

  In particular, with regard to the wire part of the paper machine, from the viewpoint of improving the dewatering capacity, the long net type former has been shifted to the on-top type twin wire former and further to the gap former. In the gap former type paper machine (paper machine whose wire part is a gap former), the raw material jet ejected from the head box is immediately sandwiched between two wires, so the surface of the raw material jet is less disturbed and the surface quality is good. . In addition, the gap former type paper machine has the advantage that the difference between the front and back sides is small compared to conventional former types such as the long net type and the on-top type because the paper layer can be dehydrated from both sides of the paper layer and the amount of dewatering can be easily adjusted. is there.

  On the other hand, in the gap former type paper machine, since the paper concentration is very thin, it dehydrates rapidly from both sides of the paper layer, so the fine fibers and filler in the paper layer are localized to the surface layer, and the middle layer of the paper There is a problem in that the amount of fine fibers is reduced, and thereby the interlaminar strength is remarkably lowered, and the yield of the stock and ash on the wire in the paper making process is remarkably lowered.

  For this reason, in the coated paper for printing manufactured with a gap former type paper machine, the interlayer strength of the base paper is small, so the moisture in the base paper that has evaporated by heat drying after offset printing passes through the coating layer. In some cases, peeling occurs between the paper layers, causing a phenomenon that the coating layer swells (blister phenomenon), which may cause serious quality problems such as rough printing.

  As a method for improving the blister of the coated paper for printing, for example, there is a method of increasing the interlayer strength of the coated base paper of the coated paper for printing. In general, in order to improve the interlaminar strength, a method of adding a paper strength improver such as polyacrylamide or cationized starch in the paper making process is used from the soft side (raw material formulation). However, in the case of polyacrylamide, if it is added until a sufficient effect is obtained, the cost increases with expensive polyacrylamide, and the cohesiveness is strong, so that the formation is deteriorated and the printing quality is lowered. On the other hand, in the case of cationized starch, since a larger amount of addition is required than polyacrylamide, the drainage is deteriorated, causing problems such as poor dehydration, increased drying load, and reduced wet paper strength.

  Furthermore, it has been proposed at the laboratory experiment level to improve paper strength by combining cationized starch and polyacrylamide as a paper strength improver (see Patent Document 1). However, at the actual machine level, even if the interlayer strength of the coated paper is increased, it is difficult to sufficiently improve the water breakage on the wire, and in addition, the air permeability of the coated base paper deteriorates. Addition of silica sol is necessary (see Patent Document 2).

In addition to the addition of an internally added paper strength improver, a method of improving the interlayer strength by applying an externally added paper strength improver has also been proposed (see Patent Document 3). However, in the base paper made with a gap former type paper machine, fine fibers are localized on the surface of the paper to form a dense layer, so that the paper strength improver does not penetrate into the base paper and obtains a sufficient effect. It ’s difficult.
JP 2003-301398 A Japanese Patent Laid-Open No. 10-251991 Japanese Patent No. 3744115

  When making a base paper for printing using a gap former type paper machine, there has been a problem that the interlaminar strength of the base paper for coating is reduced and the blistering resistance of the coated paper is reduced. In particular, there is a problem that the interlaminar strength of the paper is remarkably reduced due to an increase in dry addition and a decrease in compressibility of the wet paper in the press because the drainage rate is reduced when making paper under high speed conditions because of a high filler content in the paper. . And although it has been proposed to add a paper strength improver to such a problem, the formation of paper deteriorates due to the cohesiveness of the paper strength improver simply by adding a paper strength improver. The problem arises.

  In view of such a situation, an object of the present invention is a method for producing a coating base paper for printing using a gap former type paper machine, wherein the dehydrating property of the stock is good, and the interlayer of the resulting coating base paper An object of the present invention is to provide a method for producing a coated base paper for printing which has a sufficiently high strength and a good texture.

  As a result of diligent research on the above problems, the present inventors have printed by a neutral papermaking method using a gap-former type paper machine of a roll and blade former type having a dewatering mechanism by a dewatering blade immediately after initial dewatering by a forming roll. In the method of making coated base paper, it is high while maintaining good drainage and formation by adding a specific amount of cationized starch and synthetic paper strength improver to the raw material in combination as a strength improver It has been found that interlayer strength can be imparted, and the present invention has been completed.

  That is, the above problems can be solved by making a printing base paper by using a certain amount of cationized starch and a synthetic paper strength improver as a paper strength improver to be added to the raw material of the base paper. It is more effective in the process of manufacturing the coated paper for printing using the gap former type paper machine provided.

  Furthermore, by applying an aqueous solution mainly composed of an adhesive to the obtained base paper with a film metalling type size device, a printing base paper having higher interlayer strength and a printing coating using the same Paper can be obtained.

  By carrying out the present invention, it is possible to obtain a coated base paper and a coated paper having a high interlayer strength while maintaining good paper formation without impairing the drainage during papermaking. In particular, when the present invention is applied to the production of printing base paper and coated paper having a high papermaking speed and a high filler content in the paper, the effect of the invention is great.

  In the present invention, it is indispensable to use a gap-former type paper machine of the roll and blade former type having a dewatering mechanism with a dewatering blade immediately after the initial dewatering with the forming roll, and to use the cationized starch and the synthetic paper strength agent in combination. As a result, the interlaminar strength of the coated base paper due to the gap former, the drainage due to the cationized starch, and the formation deterioration due to the synthetic paper strength agent can be improved. As a result, a coated base paper having high interlaminar strength and good drainage and formation can be obtained.

  The present invention uses a roll and blade former type gap former type paper machine having a dewatering mechanism with a dewatering blade immediately after the initial dewatering with a forming roll, and is used for printing at a papermaking speed of 1300 m / min or more by a neutral papermaking method. This is a method for producing a coated base paper or a coated paper for printing. As a paper strength improver, 0.10 to 0.30% by weight of cationized starch and 0.10 to 0.60% by weight per pulp for paper The synthetic paper strength improver is added.

  The present invention is a manufacturing method using a high-speed gap former type paper machine, and in particular, uses a roll and blade former type gap former type paper machine having a dewatering mechanism using a dewatering blade immediately after initial dewatering using a forming roll. In the roll-and-blade type gap former, the first dewatering is performed in the lap area of the forming roll having the vacuum, and immediately after that, the blade dewatering is performed by the pressure blade module. This mechanism makes it possible to dewater more slowly than the conventional former, so that a paper having a more uniform paper layer structure and texture can be obtained. If the diameter of the forming roll used at this time is small, a sufficient holding angle cannot be obtained and adjustment of dewatering becomes insufficient. Therefore, the diameter of the forming roll is preferably 1500 mm or more. Furthermore, the distribution of fine fibers and fillers in the paper layer can be made uniform by imparting microturbulence to the wet paper layer with a pulse force from a pressure-type dehydrating blade to promote fiber dispersion. In addition to a dewatering mechanism using a forming roll or a blade, dryness can be adjusted by appropriately using a dewatering device such as a suction unit or a high vacuum suction box in the subsequent stage.

  Furthermore, the present invention is particularly effective in a process for producing a coated paper for printing using a gap former type paper machine equipped with an on-machine coater. Further, the present invention can be preferably applied when the filler content in the paper is high. The higher the filler content in the paper, the lower the interlaminar strength, and the higher the paper making speed, the lower the yield of raw materials and chemicals, and the lower the effect of the chemicals. The present invention is effective for these problems. .

  The high speed as used in the field of this invention is 1300 m / min or more, Preferably it is 1500 m / min or more. The effect obtained by applying the present invention becomes more prominent at 1600 m / min or more, and can be applied to an operation at about 2500 m / min, for example.

Coated base paper The pulp raw material of the base paper for printing produced in the present invention is not particularly limited, and is not limited to mechanical pulp (MP), deinked pulp (DIP), hardwood kraft pulp (LKP), conifer craft. Any material that is generally used as a papermaking raw material for printing paper, such as pulp (NKP), may be used, and one or more of these may be used as appropriate. Mechanical pulp includes groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), chemiground pulp (CGP), semi-chemical pulp (SCP), alkaline peroxide Examples include hydrogen mechanical pulp (APMP) and alkali hydrogen peroxide thermomechanical pulp (APTMP). The deinked pulp may be any deinked pulp made from high-quality paper, medium-quality paper, low-grade paper, newspaper, flyers, magazines, etc., or unselected waste paper mixed with these. Absent. In the present invention, even if the deinked pulp is blended in an amount of 20% by weight or more, further 30% or more by weight, the effect of improving the interlayer strength can be exhibited while maintaining a good formation. From the standpoint of strength, the amount of deinked pulp is preferably 80% by weight or less.

  In the present invention, known fillers can be used. For example, heavy calcium carbonate, light calcium carbonate, clay, silica, light calcium carbonate-silica composite, kaolin, calcined kaolin, deramikaolin, magnesium carbonate, barium carbonate, barium sulfate, aluminum hydroxide, calcium hydroxide, hydroxide Inorganic fillers such as amorphous silica produced by neutralization of magnesium, zinc hydroxide, zinc oxide, titanium oxide and sodium silicate, urea-formalin resin, melamine resin, polystyrene resin, phenol resin, micro Organic fillers such as hollow particles, acrylamide composites, wood-derived substances (fine cellulose, microfibril fibers, powder kenaf), modified insolubilized starch, non-gelatinized starch can be used alone or in combination. In addition, as a calcium carbonate-silica composite, the composite described in Unexamined-Japanese-Patent No. 2003-212539 and Japanese Patent Application No. 2004-27483 can be illustrated. In addition to calcium carbonate and / or light calcium carbonate-silica composite, amorphous silica such as white carbon may be used in combination. Among these, calcium carbonate and light calcium carbonate-silica composite, which are typical fillers for neutral papermaking and alkaline papermaking, are preferably used.

  The compounding rate of the filler contained in the base paper of the coated paper for printing produced in the present invention is 1 to 40 solids by weight. In papermaking, the higher the filler content in paper, the lower the interlayer strength and yield. Accordingly, the effect of the present invention is greater when the present invention is applied to the production of coated paper for printing having a high filler content in the paper. From this viewpoint, the filler content in the paper is preferably 10 to 40% by weight, more preferably 12 to 35% by weight.

  In the present invention, 0.10 to 0.30% by weight of cationized starch per paper pulp is used. Examples of the cationized starch used as a paper strength improver in the production method of the present invention include tertiary amine-based and quaternary ammonium-based cationized starch. The tertiary amine system mentioned here is a reaction of starch with 2-dialkylaminoethyl chloride, and the quaternary ammonium system is a reaction of starch with a trialkylamine such as trimethylamine or triethylamine and epichlorohydrin. It has been made. The charge density of the cationized starch is not particularly limited, but it is often abundant in anionic substances derived from the coating solution, and the required amount of cation is extremely high. An improvement effect can be expected. Specifically, 0.1 meq / g or more is preferable, and 0.15 meq / g or more is more preferable. Further, if the charge density is too high, the system tends to rotate positively, so 5.0 meq / g or less is preferable.

  The addition amount of the cationized starch added in the present invention is 0.10 to 0.30% per paper pulp, and preferably 0.15 to 0.28%. When the added amount of the cationized starch is less than 0.10%, sufficient interlayer strength as a coated paper for printing cannot be obtained. If it exceeds 0.30%, the interlaminar strength increases, but the drainage on the wire and the squeezing by the press deteriorate, and problems such as poor dehydration and increased drying load occur.

  In the present invention, in addition to the above cationized starch, a synthetic paper strength improver of 0.10 to 0.60% by weight per paper pulp is used in combination. Synthetic paper strength improvers used in the present invention include starch and acrylamide graft copolymers, copolymers of various ionic polyacrylamides, acrylamides and / or methacrylamides and cationic and / or anionic monomers, melamine resins And urethane resin. These paper strength improvers are characterized by having either a primary to tertiary amino group or a quaternary ammonium salt as an ionic functional group, or a plurality of cationic functional groups, It may have an anionic functional group such as carboxylic acid and sulfonic acid. Accordingly, a cationic synthetic paper strength improver or a zwitterionic synthetic paper strength improver can be used in combination. In the present invention, the synthetic paper strength improver used in combination with the cationized starch is preferably a polyacrylamide (PAM) strength improver from the viewpoints of the effects and handling of the present invention, and in particular, zwitterionic polyacrylamide based paper. A power improver is preferred. Furthermore, as the synthetic paper strength improver of the present invention, a cation-rich amphoteric PAM-based strength improver is particularly preferred, and specifically, the ratio of cationic charge density / anionic charge density is in the range of 1.2 to 5.0. A certain amphoteric polyacrylamide is preferable, more preferably in the range of 1.2 to 3.5, and still more preferably in the range of 1.2 to 2.5. The addition amount of the synthetic paper strength improver is 0.10 to 0.60% by weight in order to improve the formation. When it is less than 0.10% by weight or exceeds 0.60% by weight, there is a problem inferior in formation.

  As other internal chemicals, inorganic chemicals such as sulfuric acid band and polyaluminum chloride, chemicals such as wet paper strength improver, drainage improver, dye, neutral sizing agent and yield improver are used as necessary. May be. Examples of the wet paper strength improver include polyamidoamine epichlorohydrin. Examples of neutral sizing agents include alkyl ketene dimers, alkenyl succinic anhydrides, and neutral rosin sizing agents. These internally added chemicals are also added within a range that does not affect operability. As the yield improver, cationic, anionic, or nonionic polyacrylamide, or a combination of these with anionic fine particles such as bentonite and colloidal silica can be used as necessary.

  Further, in the present invention, by adding a polymer called a coagulant to the papermaking system, it is possible to neutralize the anion interfering substance in the system that inhibits the effect of improving the paper strength of starch and paper strength agent. The effects of the invention can be amplified. Coagulants used include polyethyleneimine and modified polyethyleneimines containing tertiary and / or quaternary ammonium groups, polyalkyleneimines, dicyandiamide polymers, polyamines, polyamine / epichlorohydrin polymers, and dialkyldiallyl quaternary ammonium monomers , Dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl acrylamide, polymers of dialkylaminoalkyl methacrylamide and acrylamide, polymers of monoamines and epihalohydrin, polymers with polyvinylamine and vinylamine moieties, and mixtures thereof In addition to the cationic polymer, anionic groups such as carboxyl groups and sulfone groups are copolymerized in the polymer molecule. Cation-rich zwitterionic polymers, and a mixture of cationic polymer and an anionic or zwitterionic polymer. The coagulant in the present invention is not limited to the above substances as long as it has a coagulation action on an anion interfering substance. Among the coagulants having a coagulation action with respect to the anion interfering substance, a polymer containing a dialkyldipotassium quaternary ammonium monomer is more preferable. Moreover, as a compounding quantity of a coagulant, 50-1000 ppm is preferable with respect to paper stock solid content.

  The forming part of the paper machine used in the present invention is a roll-and-blade type gap former, and the dewatering conditions such as blade pressure are not particularly limited and can be appropriately set within the normal operating range. The press part in the production method of the present invention preferably uses a shoe press. When the paper making speed is high, the dryness after pressing can be improved by more preferably processing in two or more stages. Strength such as length is improved. In the present invention, the shoe press is a type in which a sheet is passed between a press roll that is rotationally driven and a pressure shoe that is hydraulically pushed up, and a sleeve is run between the felt and the pressure shoe. The nip width of the press can be appropriately adjusted, and 150 to 250 mm is preferably used. The pressing pressure can be appropriately adjusted by taking into account the moisture at the outlet of the press and the difference between the front and back sides, and the processing conditions are preferably 100 kN / m to 1100 kN / m, more preferably 500 kN / m to 1100 kN / m.

In the present invention, the paper machine pre-dryer and the after-dryer can use public equipment, and the drying conditions are not particularly limited, and can be appropriately set within the normal operating range.
In the coated base paper of the present invention, by applying a clear coating liquid mainly composed of an adhesive as necessary, in addition to improving the surface properties of the coated base paper, the interlayer strength due to the penetration of the adhesive is improved. can do. The adhesive amount of the clear coating layer is preferably 80% by weight or more in terms of solid content, and the coating amount of the clear coating layer is preferably 0.5 to 3.0 g / m ² in terms of solid content. Adhesives used as the main component of the clear coating solution include raw starch, oxidized starch, esterified starch, cationized starch, enzyme-modified starch, aldehyde-modified starch, etherified starch (wet low molecular weight hydroxyethylated starch) Modified starch such as dry low molecular weight hydroxyethylated starch), ionic polyacrylamide, carboxymethyl cellulose, polyvinyl alcohol and the like, and the solid content concentration is 2 to 14% by weight, preferably 3 to 12% by weight. %. When the solid content concentration is 2% by weight or less, the permeability of the clear coating liquid to the base paper is good, but the amount of penetration increases, so the drying load after coating increases, and as in the present invention Not suitable for high speed papermaking. On the other hand, when the content is 14% by weight or more, the viscosity of the coating liquid is increased, so that the permeability is lowered and sufficient strength cannot be obtained. In addition to the adhesive, a sizing agent, a surfactant, a humectant, an antifoaming agent, and the like can be used in combination with the clear coating solution.

  As the coating apparatus of the present invention, a rod metering size press coater, a blade metering size press coater, a gate roll coater, and a two roll size press can be used. It is preferable to use a press coater.

  In the present invention, pre-calendar treatment with a soft calender or the like may be applied to the above-described clear coated coated base paper or a coated base paper not subjected to clear coating before coating the pigment coating liquid. In the present invention, a coated paper can also be obtained by applying a pigment coating solution containing a pigment and an adhesive to the base paper instead of the clear coating.

  As for the pigment used in the pigment coating liquid mainly composed of pigment and adhesive, heavy calcium carbonate is mainly used, but light calcium carbonate, kaolin, clay, talc, satin white, Use plastic pigment, titanium dioxide, etc. together. In addition, the adhesive used in the pigment coating solution includes various copolymer emulsions such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, and synthetic systems such as polyvinyl alcohol and maleic anhydride copolymer. Adhesive, oxidized starch, esterified starch, enzyme-modified starch, etherified starch, cold water soluble starch obtained by flash drying them, and the like are used. In the pigment coating liquid of the present invention, various auxiliary agents blended in ordinary coated paper pigments such as a dispersant, a thickener, a water retention agent, an antifoaming agent, and a water resistance agent may be used.

The coating amount of the pigment coating solution, preferably, it is preferable to both surfaces coated with a range of 0.7~10g / ^{m 2} in solid per sheet one surface fraction, more preferably 1 to 10 g / ^{m 2,} more preferably Is 2-8 g / m ² , most preferably 2-5 g / m ² . When the amount is less than 0.7 g / m ² , coating is difficult, and when the concentration of the coating solution is lowered, the penetration of the coating solution into the base paper increases and the surface property tends to deteriorate. When coating an amount larger than 10 g / m ² , it is necessary to increase the coating solution concentration, and it is difficult to control the coating amount on the apparatus. The coated paper dried after coating may be subjected to a pre-calendar treatment with a chilled calendar, a soft calender or the like before coating with the top coat pigment coating solution.

  In the present invention, the above-described clear-coated base paper, or on the base-coated paper obtained by subbing the base paper with a pigment coating liquid containing a pigment and an adhesive instead of the clear coating, A coated paper may be produced by overcoating a pigment coating solution containing a pigment and an adhesive.

The pigment, adhesive composition, blending amount, coating amount, etc. of the topcoat pigment coating liquid are not particularly limited, and generally used pigments and adhesives may be used. As for the pigment, heavy calcium carbonate is mainly used, and light calcium carbonate, kaolin, clay, talc, satin white, plastic pigment, titanium dioxide and the like are used in combination according to the required quality. In addition, the adhesive used in the pigment coating solution includes various copolymer emulsions such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, and synthetic systems such as polyvinyl alcohol and maleic anhydride copolymer. Adhesive, oxidized starch, esterified starch, enzyme-modified starch, etherified starch, cold water soluble starch obtained by flash drying them, and the like are used. In the pigment coating liquid of the present invention, various auxiliary agents blended in ordinary coating paper pigments such as a dispersant, a thickener, a water retention agent, an antifoaming agent, and a water resistance agent may be used. The coating liquid concentration is preferably 55 to 70%, and the coating amount is preferably 6 to 14 g / m ² in terms of solid content on one side. The top coating apparatus is not particularly limited, but a fountain blade coater or a roll application blade coater is usually used. The coated paper dried after applying the topcoat pigment coating solution is glossed by a finishing process such as a super calender or a soft calender as usual.

There are no particular limitations on the type and processing conditions of the calender device, and a public calender such as a normal calender made of metal roll, soft nip calender, or high temperature soft nip calender is selected as appropriate, and these are selected according to the quality target value of printing paper. The conditions may be set within the controllable range of the apparatus. Although there is no limitation also about the basic weight of the coating paper for printing produced by the manufacturing method of this invention, it is 30-120 g / m < ² > normally, Preferably it is 35-80 g / m < ² >, More preferably, it is 40-. It is more effective at 60 g / m ² .

  In the present invention, in particular, papermaking, coating and calendering are performed continuously, and when the paper is passed online to obtain a coated base paper or a coated paper using the same, the drainage and texture are improved. The effect of the present invention is that the coating base paper for printing capable of imparting high interlayer strength while maintaining, and that the coated paper using the coating base paper can be obtained with a blister resistance and good printing quality can be obtained. It is something that demonstrates.

  Moreover, the base paper for printing produced in the present invention and the coated paper using the same can be used for various printing applications such as offset printing and gravure printing.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, naturally this invention is not limited to these. In the present specification, “part” and “%” respectively represent “part by weight” and “% by weight” unless otherwise specified.

<Evaluation method>
The evaluation method of the measurement item used for the following examples and comparative examples is shown below.
(1) Dewaterability in machine The dewaterability in a paper machine was visually evaluated in the following three stages based on normal conditions.
◎: Dehydration better than usual, ○: Normal degree (relatively good dehydration), △: Dehydration worse than usual, ×: Dehydration worse than usual, and operability decreased (2) Interlaminar strength of paper
The interlayer strength was measured using L & W ZD Tensile Tester SE 155 (manufactured by Lorentzen & Wettre).

(3) Formation of coated base paper The formation of the coated base paper was evaluated by the formation index. Regarding the formation index, the formation index (A) measured by Nomura Corporation's total land FMT-III (light transmission fluctuation method) and the formation index (B) measured by Metso's BM meter on-line total The conversion formula was prepared in advance using the coated base paper, and the conversion formula was evaluated as the formation index of FMT-III. Here, the formation index indicates that the smaller the numerical value, the better the formation.
(Conversion formula) A = 0.31 × on-line measurement value (B) +2.6 (R ² = 0.99)
(4) Printing evaluation Using an offset rotary printing press (4 colors, Toshiba B2T600) with an off-wheel printing ink (Reo Echo SOY M manufactured by Toyo Ink Mfg. Co., Ltd.), a printing speed of 500 rpm and a paper surface temperature of 120 ° C. during drying. Printed at The print reproducibility of the 50% halftone dot portion of the obtained printed matter was visually evaluated according to the following criteria (（: very good, ○: good, Δ: slightly inferior, ×: inferior). Furthermore, the presence or absence of the occurrence of blisters was confirmed for the four-color solid portion (◯: not generated at all, Δ: hardly generated, x: generated).

<Making paper for printing>
(1) Paper machine / paper machine A: Gap-former paper machine / paper machine B of roll and blade former type B: Twin wire type paper machine of twin wire type (2) Pulp raw material / LBKP: Hardwood kraft pulp (freeness) (CSF = 350ml)
・ NBKP: Conifer kraft pulp (freeness CSF = 600ml)
・ DIP: Deinked pulp (freeness CSF = 240ml)
-DBP: Drive-loak pulp (3) Internal chemicals-Sulfuric acid band (aluminum sulfate): AS-N (50% product) was diluted and used.
Coagulant: N7527 manufactured by Katayama Narco was diluted and used.
-Yield: Samar R-300 was diluted and used.

(4) Filler rate in paper (ash content in paper)
Rosetta-type light calcium carbonate (average particle size: 3.5 μm) was used, and the amount added was appropriately adjusted so as to achieve the target ash content in paper.

(5) Preparation of pigment coating liquid To 70 parts of heavy calcium carbonate and 30 parts of kaolin, 0.3 part of sodium polyacrylate dispersant is added and dispersed in water using a cowless disperser and bonded. As an agent, 5 parts of phosphate esterified starch and 10 parts of styrene / butadiene copolymer latex were blended to prepare a topcoat pigment coating solution having a solid content of 65%.

[Example 1]
Filler was mixed with pulp containing 10% NBKP, 50% LBKP, 30% DIP, and 10% DBP (addition of 100 ppm coagulant) so that the ash content in the paper was 15%. After 0.5% aluminum sulfate is added to the mixed paper stock per weight of the solid content of the paper stock, cationized starch (Cato304, manufactured by NSC Japan) as an internal paper strength improver is added to the paper stock pulp at a rate of 0.00%. 27% added, and cation-rich amphoteric PAM (Harima Kasei Co., Ltd., EX288) as a synthetic paper strength agent is 0.4% per paper pulp, and a cationic polyacrylamide-based retention agent (manufactured by Somare, A paper stock was prepared by adding 400 ppm of R-300) to the paper pulp and 100 ppm of a coagulant. Using the gap-former type paper machine A of roll and blade former type, the prepared stock is made into a coated base paper having a base paper weight of 50 g / m ² at a paper making speed of 1600 m / min and an ash content of the base paper of 15%, After the pre-calendar treatment, the coating solution for top coating is continuously applied with a blade coater and dried on both sides with a target of a coating amount of 10 g / m ² per one side of the base paper. As described above, high-temperature soft nip calendering was performed under the conditions of a roll surface temperature of 150 ° C., a linear pressure of 250 kN / m, and a calender nip number of 6 nips to produce coated paper for printing.

[Example 2]
A coated paper for printing was obtained in the same manner as in Example 1 except that the addition amount of the cationized starch in Example 1 was changed to 0.15%.

[Example 3]
A coated paper for printing was produced in the same manner as in Example 1, except that the addition amount of the cationized starch of Example 1 was 0.10% and the addition amount of amphoteric PAM was 0.6%.

[Example 4]
A coated paper for printing was produced in the same manner as in Example 1 except that the papermaking speed in Example 1 was 1800 m / min.

[Example 5]
A coated paper for printing was produced in the same manner as in Example 1 except that the stock of Example 1 was NBKP 10%, LBKP 60%, DIP 20%, and DBP 10%.

[Example 6]
A coated paper for printing was produced in the same manner as in Example 1 except that the stock NBKP of Example 1 was 10%, LBKP 20%, DIP 60%, DBP 10%, and the amphoteric PAM addition amount was 0.6%.

[Example 7]
A coated base paper for printing is produced under the same conditions as in Example 1, and before applying the pigment, a rod metalling size press coater is used to form a 6% solid content oxidized starch (Nippon Corn Starch Co., Ltd.) as a clear coating solution. A SK-20) aqueous solution was coated on both sides at 2 g / m ² per side to prepare a printing base paper for printing, and a pre-calendar treatment was performed.

Subsequently, the coating liquid for overcoating is continuously coated with a blade coater and coated on both sides with a target of a coating amount of 10 g / m ² per one side of the base paper. Further, as a surface treatment online, a roll surface temperature of 150 ° C. High-temperature soft nip calendering was performed under the conditions of a linear pressure of 250 kN / m and a calender nip number of 6 nips to produce coated paper for printing.

[Comparative Example 1]
A coated paper for printing was produced in the same manner as in Example 1 except that the addition amount of the cationized starch in Example 1 was changed to 0.08%.

[Comparative Example 2]
A coated paper for printing was produced in the same manner as in Example 1 except that the addition amount of the cationized starch in Example 1 was 0.4%.

[Comparative Example 3]
A coated paper for printing was produced in the same manner as in Example 1 except that the addition amount of the cationized starch in Example 1 was 0.6%.

[Comparative Example 4]
A coated paper for printing was produced in the same manner as in Example 1 except that the addition amount of the cationized starch of Example 1 was 0.1% and the addition amount of amphoteric PAM was 0.8%.

[Comparative Example 5]
In twin wire paper machine B of twin wire type, 0.5% aluminum sulfate was added to the stock (NBKP10%, LBKP50%, DIP30%, DBP10%) mixed with pulp and filler, based on the solid weight of the stock. Thereafter, cationized starch (manufactured by NSC Japan, Cato304), an internal paper strength improver, was added at 0.2% per paper pulp, and a cation-rich amphoteric PAM (manufactured by Harima Chemical Co., Ltd., EX288) is 0.12% per paper pulp, and a cationic polyacrylamide retention agent (Somale, R-300) as a yield improver is added at 250 ppm per paper pulp, and the base paper is made at a papermaking speed of 1050 m / min. A coated base paper having a basis weight of 44 g / m ² and an ash content of 15% in the base paper was prepared, and after pre-calendar treatment, the coating liquid for top coating was continuously applied per side of the base paper with a blade coater. Double-sided coating and drying were performed with the goal of a work amount of 10 g / m ² to produce a coated paper for printing.

Table 1 shows the experimental results. By increasing the rate of addition of cationized starch or amphoteric PAM, which is a paper strength improver, the correlation strength of the coated paper tended to increase.
However, as shown in Comparative Example 1, when the starch addition rate was as low as 0.08%, the interlayer strength was too low to generate blisters, and the print quality was significantly impaired. On the other hand, when the starch addition rate is as high as 0.4% and 0.6% as in Comparative Examples 2 and 3, the dehydrating property in the machine deteriorates, which causes an increase in the steam cost for drying and the like. The

  Moreover, when the amphoteric PAM addition rate is as high as 0.8% as in Comparative Example 4, although the dehydrating property is improved, the formation becomes extremely worse, and as a result, the PAM addition rate is lower than that of Example 4 with a lower PAM addition rate. As a result, the reproducibility was inferior as the strength of the layer decreased.

  By appropriately combining cationized starch and amphoteric PAM within the scope of the present invention, a coated paper free from blistering problems could be obtained even when highly deinked pulp was blended (Example 6). In general, when deinked pulp is highly blended, blistering is likely to occur because the strength is lower than that of virgin pulp, and this tendency is prominent in gap formers in which fine fibers tend to be unevenly distributed on the surface. However, according to the present invention, a coated paper free from blister problems can be obtained, which is extremely suitable.

Further, by applying clear coating, a good coated paper having excellent print reproducibility and free of blistering was obtained (Example 7).
As can be seen from Table 1, in order to produce a high-quality printing coated paper of the same quality as the conventional coated paper (Comparative Example 5) produced by a relatively low speed twin wire former. It was effective to use a cationized starch and a cation-rich amphoteric PAM in an appropriate addition rate using a gap former type paper machine.

  From the above, by carrying out the present invention, when producing coated paper for printing by a neutral papermaking method at high speed using a gap former type paper machine, the paper ground without impairing the drainage of the paper machine. It is possible to produce a good coated paper for printing that has a high interlayer strength and is less likely to generate blisters while maintaining good adhesion.

Claims (8)

Immediately after the initial dewatering by the forming roll, using a gap-former type paper machine of the roll-and-blade former type with a dewatering mechanism by the dewatering blade, the coated paper for printing at a papermaking speed of 1300 m / min or more by the neutral papermaking method. In the manufacturing method,
The paper strength improver is characterized by adding 0.10 to 0.30% by weight of cationized starch and 0.10 to 0.60% by weight of a synthetic paper strength improver per paper pulp. Manufacturing method of coated paper for printing.   The manufacturing method of the coated paper for printing of Claim 1 whose said synthetic paper power improver is a polyacrylamide type paper power improver.   The manufacturing method of the coated paper for printing of Claim 1 or 2 whose said synthetic paper power improver is an amphoteric polyacrylamide type paper power improver.   The synthetic paper strength improver is an amphoteric polyacrylamide-based strength improver having a cationic charge density / anionic charge density ratio in the range of 1.2 to 5.0. The manufacturing method of the coated paper for printing of description.   The method for producing a coated paper for printing according to any one of claims 1 to 4, wherein a cationic coagulant is further added.   6. The method according to any one of claims 1 to 5, further comprising applying an aqueous solution having a solid content concentration of 2 to 14% by weight, the main component of which is an adhesive, using a film pressing type size press. The manufacturing method of the coated paper for printing of description.   The manufacturing method of the coated paper for printing of any one of Claims 1-6 in which 20 weight% or more of deinked pulp (DIP) is contained in raw material pulp. Using a roll and blade former type gap former type paper machine having a dewatering mechanism with a dewatering blade immediately after the initial dewatering with a forming roll, a paper base for printing at a papermaking speed of 1300 m / min or more by the neutral papermaking method. In the manufacturing method,
The paper strength improver is characterized by adding 0.10 to 0.30% by weight of cationized starch and 0.10 to 0.60% by weight of a synthetic paper strength improver per paper pulp. A method for producing coated base paper for printing.