JP5374181B2 - Coated paper for printing and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing coated paper for printing, having needle penetration resistance and a high surface strength, in a good operability. <P>SOLUTION: This method for producing the coated paper for printing by installing at least &ge;1 layer of a coated layer containing a pigment and binder on stock paper includes: obtaining a high quality coated paper for printing in the good operability by size-pressing an aqueous starch solution having 12-20 wt.% solid part concentration on the base paper by a rod-metering coating method by using a plane rod. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a coated paper for printing. In particular, the present invention relates to a coated paper for printing having both high needle-out resistance and surface strength, and relates to a production method that can be efficiently produced with good operability.

  In recent years, in order to convey the content visually visually, printing such as using a lot of photographs and designs and making it full color has been increasingly applied to coated paper for printing. There is a need for a coated paper for printing. On the other hand, there is a strong demand for paper weight reduction in terms of resource saving and transportation cost. Further, as one of the qualities required for paper products, it is required to produce bulky paper. In order to manufacture lightweight coated paper for printing, from the viewpoint of environmental protection, in order to effectively use paper pulp produced from forest resources, a coated paper that is lightweight while maintaining the paper thickness is used. It is required to manufacture. Furthermore, considering that good printability is imparted to the coated paper for printing, it is possible to lower the basis weight of the coated paper by lowering the basis weight of the base paper while maintaining a constant coating amount. It is done. However, in the coated paper, if the basis weight of the base paper is lowered while maintaining a high coating amount, there is a problem that “needle dropout” is likely to occur when the printed material is stapled and bound. In particular, it was more likely to occur when the density of the base paper was lowered.

  “Needle dropout” refers to a phenomenon in which the center page falls out of a staple in staple binding. When the paper is folded by a folding machine during printing, the pulling strength of the crease portion of the paper is reduced, and when the staple is subsequently bound, the paper breaks along the needle. .

  As a method for solving the needle omission, it is important to increase the tensile strength of the fold portion. In order to increase the tensile strength of the crease portion, it is conceivable to suppress the phenomenon that the coating layer breaks at the crease portion when the coated paper is folded, that is, the occurrence of so-called folding. In order to suppress the occurrence of cracking, it is simplest to increase the elasticity of the entire coated paper by lowering the coating amount of the coating layer mainly composed of pigment (hereinafter referred to as pigment coating layer). It is a simple method. However, if the coating amount of the pigment coating layer is reduced, there arises a problem that excellent and good printing quality of the coated paper for printing cannot be maintained. On the other hand, by reducing the basis weight of the base paper instead of the coating amount of the pigment coating layer, the elasticity of the entire coated paper can also be increased, but in this case, the tensile strength of the entire coated paper is reduced, Not only can the occurrence of cracks be suppressed, but also the problem of missing needles cannot be improved.

  Other methods to suppress the occurrence of cracking include, for example, the use of softwood pulp with a long fiber length as a countermeasure from the base paper surface, or the jet wire ratio, which is the ratio between the raw material jet speed and the paper machine wire speed. There is a way to change it. For example, by adjusting the jet wire ratio, the ratio (= ST / SY) of the longitudinal direction (ST) and the transverse direction (SY) of the tensile strength according to JISP8113 in the coated paper is set to a specific range. A method for suppressing the occurrence of cracking is described (Patent Document 1). However, this method not only deteriorates the formation of the base paper and lowers the printability of the coated paper for printing, but according to the study by the present inventors, the effect on the decrease in the tensile strength of the crease portion is not sufficient. And it was not effective against needle dropout.

  As another method for improving the needle drop by suppressing the occurrence of cracking, a method of increasing the elasticity of the entire paper by reducing the size amount in the size press can be considered. However, this method is effective for anti-folding, but a coated paper having a low surface strength is produced due to a low size, and there is a problem that smearing occurs during offset printing. In other words, there is a relationship that makes it difficult to achieve both crack resistance (needle resistance) and surface strength. By simply increasing or decreasing the size, high crack resistance (needle resistance) and high surface strength. No coated paper having both of the above was obtained.

  As described above, the problem of needle dropout in the coated paper for printing has not been sufficiently solved, and in particular, the coated paper for printing that achieves both high resistance to needle removal and surface strength has good operability. The development of a method that can be manufactured by using this method has been desired.

JP-A-2005-171401

  In view of such a situation, an object of the present invention is to provide a method capable of producing a coated paper for printing having high surface strength without causing needle omission and with good operability.

  As a result of intensive studies on the above-mentioned problems, the present inventors have produced coated paper under specific conditions, thereby operating a coated paper for printing having high resistance to needle pull-out and high surface strength. As a result, the present invention has been completed. That is, the present invention relates to a method for producing a coated paper for printing in which at least one coating layer containing a pigment and an adhesive is provided on a base paper. In the method for producing a coated paper for printing, an aqueous starch solution having a solid content concentration of 12 to 20% by weight is applied to the base paper. This is a method for producing a coated paper for printing, in which a coating liquid containing a pigment and an adhesive is applied after being applied and dried by a size press device using a rod metalling coating method using a plain rod.

  According to the present invention, it is possible to produce a coated paper for printing having no surface loss and high surface strength without deteriorating operability. Since the method of the present invention is also suitable for low-density base paper, if the method of the present invention is used, it is possible to produce a bulky coated paper using a low-density base paper, that is, lightweight and high-quality. A certain coated paper for printing can be manufactured.

In the present invention, as the raw material pulp of the base paper, chemical pulp (conifer bleached kraft pulp (NBKP) or unbleached kraft pulp (NUKP), hardwood bleached kraft pulp (LBKP) or unbleached kraft pulp (LUKP) Etc.), mechanical pulp (groundwood pulp (GP), refiner mechanical pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc.), deinked pulp (DIP), etc. alone or in any proportion Can be mixed and used. In this invention, it is preferable to mix | blend 30-80 weight% of mechanical pulp among the whole pulp to be used from the point of the density reduction of a coated paper. Among mechanical pulps, it is preferable to blend hardwood thermomechanical pulp, more preferably hardwood thermomechanical pulp produced from eucalyptus globulus chips, from the viewpoint of improving optical suitability such as whiteness and opacity.

In papermaking, known fillers can be arbitrarily used, such as white carbon, talc, 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, magnesium hydroxide, zinc hydroxide, zinc oxide, titanium oxide, amorphous silica produced by neutralization by mineral production of sodium silicate, etc. Inorganic fillers and organic fillers such as urea-formalin resin, melamine resin, polystyrene resin and phenol resin can be used alone or in combination. Among these, calcium carbonate or light calcium carbonate-silica composite, which is a typical filler in neutral paper or alkaline paper, is preferably used, and particularly preferably aggregated spindle-shaped light calcium carbonate or aggregated spindle-shaped light carbonate. It is preferable to use a calcium-silica composite (CaCO ₃ / SiO ₂ = 30/70 to 70/30) from the viewpoints of low density and light weight. The filler content in the paper is not particularly limited, but is preferably 10 to 40% by weight, more preferably 12 to 35% by weight.

  In making the base paper used in the present invention, known papermaking additives can be used. For example, sulfuric acid bands and various anionic, cationic, nonionic or amphoteric yield improvers, drainage improvers, paper strength enhancers and internal additive sizing agents, etc. Can be used. Furthermore, dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be added as necessary.

  In the present invention, the base paper can be made by a known paper machine such as a long paper machine, a gap former, and a hybrid former (on-top former). The papermaking conditions are not particularly defined, and the pH during papermaking may be acidic, neutral or alkaline.

In another preferred aspect of the present invention, the density of the base paper is ^{0.4g / cm 3 ~0.8g / cm 3} , more preferably 0.5~0.7g / cm ^3. If the density of the base paper is 0.4 g / cm ³ or more, the operability at the time of papermaking is improved and papermaking can be performed efficiently, which is preferable. In addition, it is preferable that the density of the base paper is 0.5 g / cm ³ or more because the resistance to needle drop is increased. Further, when the density of the base paper is 0.8 g / cm ³ or less, preferably 0.7 g / cm ³ or less, a light coated paper can be produced. Usually, if a low density base paper is used, the strength and needle pull-out property of the coated paper are deteriorated and the operability such as coating property tends to be inferior, but if the method of the present invention is used, the low density base paper is used. Even so, a coated paper having good surface strength and needle-out resistance can be produced with high operability.

In addition, the method of the present invention can produce coated paper having high resistance to needle slipping, and thus is particularly advantageous and preferable in an embodiment using a base paper having a relatively low basis weight. Specifically, the basis weight of the base paper in the present invention is preferably 30 to 80 g / m ² , more preferably 40 to 70 g / m ² .

Size press on base paper In the present invention, in order to improve the needle slip resistance and surface strength, a high concentration starch aqueous solution of 12 to 20% by weight is used for the base paper and a rod metaling method using plain rods without grooves. Press size.

  Generally, as a size press process, application by a two-roll system and application by a film transfer system are known. The two-roll method is a method in which paper is sandwiched between two rolls, a coating liquid is supplied to the nip formed between the two rolls to form a coating liquid reservoir, and the coating liquid is applied to the paper. . In the 2-roll method, the base paper absorbs the coating liquid in order to deposit the base paper in the coating liquid reservoir, and a relatively large amount of coating liquid is required to form a coating layer having a certain thickness. At that time, if the coating solution concentration is too high, the viscosity increases and it is difficult to obtain good coating suitability, so the coating solution concentration must be set low. A large amount of water is applied to the paper to make it adhere, and the speed of paper making increases due to the occurrence of wrinkles in the paper produced, the strength of the base paper being impaired, the frequency of paper breaks being increased, and the drying load being increased. It causes bad effects such as being unable to raise enough.

  On the other hand, the film transfer method is a method in which a thin film of a coating liquid is formed in advance and transferred to paper. In the present invention, by adopting the film transfer method instead of the two-roll method, it is possible to obtain a high-quality coated paper free from wrinkles at a relatively high papermaking speed without impairing the strength of the base paper.

  As a film transfer method, a gate roll type method (GRSP: Gate Roll Size Press) and a rod metering type method (RMSP: Rod Metered Size Press) are known. The gate roll type system is a system in which a thin film of coating liquid is formed on an applicator roll directly or via one or more rolls from a liquid reservoir formed between two rolls, and this is transferred to paper. It is. The gate roll type method can increase the concentration of the coating solution compared to the two-roll method, but depending on the viscosity of the coating solution or the coating speed, a wave pool phenomenon called boiling may occur, resulting in uniform coating. It may not be possible.

  On the other hand, in the rod metering method, a coating liquid is supplied from a coating liquid box, and an excess coating liquid is scraped off by a rod (stick) to form a thin film of a certain amount of coating liquid on an applicator roll. It is a method to transfer to. In the present invention, among the film transfer methods, by adopting the rod metalling method instead of the gate roll type method, it is possible to obtain a high-quality coated paper without causing operational problems such as boiling. it can.

  Furthermore, when performing a rod metering size press, there is a case where a grooved rod with a groove is used and a case where a plain rod without a groove is used. It has been found that a coated paper for printing having excellent puncture resistance and surface strength and good operability can be produced.

  That is, the present invention employs a rod metering type system, which is a kind of film transfer system, in a size press process on a base paper, and in particular, using a plain rod, a starch solution having a high concentration of 12 to 20% by weight is used as a base paper. It has been found that a coated paper for printing having excellent resistance to needle pull-out and surface strength can be produced with good operability. The concentration (12 to 20% by weight) of the starch aqueous solution used in the size press step of the present invention is very high compared to the concentration of the starch aqueous solution (about 0.5 to 3%) used in the normal size press step. Conventionally, when a high-concentration starch aqueous solution is used as in the present invention, it has been difficult to apply uniformly, and the paper profile has deteriorated and the quality of the paper has deteriorated. It has been found that a starch aqueous solution having a concentration can be applied without degrading the quality by combining with an application using a rod metalling type method, particularly using a plain rod. Furthermore, surprisingly, by producing a coated paper for printing using the size-pressed base paper obtained in this way, the coated paper for printing having both the anti-needle resistance and the surface strength is excellent. It was found that it became possible to manufacture with a reasonable operability. That is, the present invention uses a high concentration starch aqueous solution that has not been used in the past, and is applied by a specific method (rod metal ring size press and plain rod), which has not been achieved until now. This achieves both the detachability and surface strength.

  The reason why good results can be obtained by the present invention is considered as follows.

  In the size press process in the present invention, since the starch aqueous solution having a very high concentration and a high viscosity of 12 to 20% by weight is subjected to size press, the penetration of the aqueous starch solution into the base paper is suppressed, and the starch is a base paper. It will remain more on the surface of the layer, which seems to fix the fine fibers and filler on the surface of the base paper more firmly. Thereby, it is considered that high surface strength can be obtained even with a low density base paper.

  Further, in the present invention, in the rod metering size press, a plain rod is used, and the film thickness of the sizing liquid formed on the applicator roll is reduced compared to the case of using a grooved grooved rod, The amount of the size liquid transferred to the base paper is also reduced, and further, as described above, the penetration of the size liquid into the base paper is suppressed by using a high-concentration starch aqueous solution (size liquid). Therefore, in the present invention, excessive wetting of the base paper in the size press process is suppressed. In general, it is known that the elasticity of pulp decreases from wet to dry. However, in the present invention, as described above, excessive wetness of the base paper is suppressed. It is thought that the decrease in the elasticity of is suppressed. At the same time, the starch stays on the surface in the paper layer, and the water retention of the paper surface is improved, so when applying a coating liquid containing pigment and adhesive after size pressing, the coating liquid It is considered that excessive penetration of the base paper into the base paper is suppressed, thereby further suppressing the decrease in the elasticity of the pulp during drying. Due to these synergistic effects, the base paper layer in the printing coated paper of the present invention retains high elasticity and tensile strength, and it is considered that the base paper layer is prevented from being broken during the folding process during printing. . In the method of the present invention, since the penetration of the paint into the base paper can be suppressed and more starch can remain on the surface of the paper, even when a low density base paper or a base paper with high water absorption is used. Thus, a coated paper for printing having high surface strength and needle-out resistance can be produced.

  Moreover, in this invention, since the fall of the elasticity of the pulp of a base paper is suppressed as mentioned above, the base paper is maintaining high tensile strength, and the base paper is not frequently cut during the coating process. Further, in the present invention, since a plain rod is used at the time of size pressing, streaks (streak-like scratches) are less likely to occur on the coated base paper than when a grooved rod with a groove is used. Furthermore, in the present invention, since a rod metering size press is used, no boiling occurs. Furthermore, in the present invention, since a high concentration starch aqueous solution is size-pressed, the drying load is also small. For these reasons, it is considered that the method of the present invention can provide a coated paper for printing with high operability.

  As described above, the method of the present invention suppresses excessive penetration of the size liquid into the base paper and excessive penetration of the pigment coating layer into the base paper, thereby suppressing wetting of the base paper, and further, a high-concentration starch aqueous solution. Since the starch stays on the surface of the paper more by using this, it is considered that a coated paper for printing having high tensile strength and surface strength can be produced with good operability. Since the method of the present invention is also effective for a base paper having a low density and a high water absorption, it is particularly suitable for producing a bulky coated paper for printing.

  The diameter of the plain rod used in the present invention is 30 mm or more in consideration of the film forming ability of the coating liquid (size liquid) and the surface shape after coating the coating liquid mainly composed of the pigment. preferable. On the other hand, although there is no particular upper limit to the diameter of the plain rod, since the effect does not change even if the diameter of the rod is larger than 50 mm, a rod of 50 mm or less is usually used.

  In this invention, it is necessary to make the solid content concentration of the starch aqueous solution in a size press into 12 to 20 weight%. Using starch aqueous solutions with a concentration in a range other than this not only does not provide both needle-proof resistance, surface strength, and good operability, but for example, a high shear viscosity is sufficient at a concentration of 12% by weight or less. Since it cannot be obtained, the required coating amount provided on the base paper cannot be obtained, and when it is 20% by weight or more, the coating amount becomes higher than necessary due to an increase in the high shear viscosity, and the air permeability resistance of the coated paper Rises and blisters occur during web offset printing.

The amount of starch applied by the size press of the present invention is preferably about 0.5 to 1.5 g / m ² per one side of the base paper in consideration of imparting strength and preventing blistering.

  The types of starch used in the size press include oxidized starch, esterified starch such as urea phosphate esterified starch, enzyme-modified starch, etherified starch such as hydroxyethyl etherified starch, and those obtained by flash drying Cold water soluble starch etc. can be mentioned, These can be used individually or in mixture. Preferred starches include oxidized starch and hydroxyethyl etherified starch, and hydroxyethyl etherified starch is particularly preferred from the viewpoint of fluidity, film-forming property, and aging resistance.

  The operation speed of the size press apparatus is preferably 1200 m / min or more, and more preferably 1300 m / min or more. According to the present invention, troubles such as paper breakage, size control failure, streak, etc. are suppressed, and stable operation becomes possible, so the present invention is particularly suitable for high-speed operation where operability problems are important. Yes.

Pigment Application to Base Paper The method for producing a coated paper for printing of the present invention comprises a step of applying a coating liquid containing a pigment and an adhesive onto the coating base paper obtained as described above. Become. Therefore, the coated paper for printing of this invention has a pigment coating layer on the base paper in which the starch was size-pressed.

  As the pigment used in the present invention, a pigment conventionally used for coated paper can be used. For example, kaolin, clay, delaminated clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, satin white and other inorganic pigments Organic pigments such as plastic pigments, organic / inorganic composite pigments, and the like can be used. These pigments can be used alone or in admixture of two or more. In the present invention, it is preferable to use a pigment having a fine particle diameter from the viewpoint of improving the glossiness of the white paper. Specifically, a pigment having a volume average particle diameter of 0.2 to 0.6 μm measured with a master sizer of a laser diffraction method is preferably 30 parts by weight or more, more preferably 50 reception parts or more, and still more preferably. 50 to 80 parts by weight are preferably used.

As the adhesive used in the present invention, an adhesive (binder) conventionally used for coated paper can be used. For example, various latexes such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate; polyvinyl alcohol, maleic anhydride copolymer, acrylic acid Synthetic adhesives such as methyl methacrylate copolymers; proteins such as casein, soy protein, and synthetic proteins; etherified starches such as oxidized starch, positive starch, urea phosphate esterified starch, hydroxyethyl etherified starch, dextrin Etc .; Adhesives for coated paper such as cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose can be used alone or in admixture of two or more as required. Among these, it is particularly desirable to use starch and a styrene / butadiene copolymer latex in combination. As the latex, those having a glass transition temperature (T _g ) of −30 to 0 ° C. are preferable from the viewpoints of needle-out resistance and crack resistance. From the viewpoint of surface strength and operability, the particles preferably have a volume average particle diameter of 100 to 170 nm. Moreover, as starch, it is preferable to use a hydroxyethyl etherified starch for the same reason as starch for size press. As a compounding ratio of starch and latex, starch / latex = 2/7 to 6/18 is preferable by weight ratio, and more preferably 2/7 to 6/20.

  The amount of the adhesive with respect to the pigment is preferably 5 to 30 parts by weight, more preferably 7 to 20 parts by weight, and still more preferably 10 to 15 parts by weight with respect to 100 parts by weight of the pigment.

  In addition, various auxiliary agents blended in ordinary coating paper pigments such as a dispersant, a thickener, a water retention agent, an antifoaming agent, a water resistance agent, and a colorant can be used as necessary. .

  In the present invention, when a coating liquid mainly composed of a pigment and an adhesive is applied, a blade coater, a bar coater, a roll coater, an air knife coater, a reverse roll coater, a curtain coater, a size press coater, and a gate roll coater are used. One or two or more layers can be coated on one or both sides of the base paper using a coating machine that coats the base paper or sprays paint such as Optispray directly onto the base paper using a spray nozzle. it can. Among these, in consideration of image reproducibility after printing, a blade system using a flooded nip type blade coater, a jet fountain type blade coater, a short dwell time application type blade coater or the like is preferable.

In another preferred embodiment of the present invention, the coating amount (solid content weight) of the coating layer containing a pigment and an adhesive is preferably 10 to 25 g / m ² , more preferably 12 to 20 g / m ² per side. m ² . If it is 10 g / m ² or more, aesthetic printing quality such as halftone dot reproducibility and surface strength and printing workability can be satisfied. Moreover, if it is 25 g / m < ² > or less, since air permeability resistance becomes low, generation | occurrence | production of the blister at the time of offset rotary printing is suppressed, and it is preferable. The coating layer may be a single layer or a multilayer.

  In the present invention, there is no limitation on the method for drying the wet coating layer, and various methods such as a steam superheating cylinder, a heated hot air air dryer, a gas heater dryer, an electric heater dryer, an infrared heater dryer, etc. may be used alone or in combination. Can do.

The coated paper coated and dried as described above may be used without being subjected to calendaring, or may be smoothed by super calendering, high-temperature soft nip calendering, or the like as necessary.

  The printing coated paper of the present invention can correspond to various printing methods, and can be used for offset printing coated paper, relief printing coated paper, gravure printing coated paper, and the like. In particular, the coated paper for printing of the present invention can be suitably used for offset printing applications, and is particularly suitable for offset rotary printing applications.

The basis weight of the coated paper of the present invention is not particularly limited, but a basis weight of about 70 to 110 g / m ² is good in consideration of strength and operability during printing. The density of the coated paper of the present invention is not particularly limited, but is preferably about 0.8 to 1.1 g / cm ^{3 in} view of strength and lightness.

As described above, the present invention provides a coated paper manufacturing method in which at least one coating layer containing a pigment and an adhesive is provided on a base paper. It is characterized in that a size rod is pressed by a ring coating method and a plain rod without a groove is used as the rod, and thus, a coated paper for printing having high resistance to needle removal and surface strength is excellent. It can be manufactured with high speed operability. Preferably, in the present invention, the basis weight of the base paper is 30 to 80 g / m ² , the density of the base paper is 0.4 to 0.8 g / cm ³ , and the coating amount of starch on one side of the base paper is 0. .5~1.5g / m ^2, the coated amount per one surface of the pigment layer into the base paper coated with starch is 10 to 25 g / m ^2, the basis weight of the coated paper 70~110g / m ² and the density of the coated paper is 0.8 to 1.1 g / cm ³ .

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited at all by these. Unless otherwise specified, in the present specification, “part” and “%” respectively represent “part by weight” and “% by weight”, and the numerical range is described as including the end points.

  Evaluation methods for the coating liquid used in this example and the obtained coated paper for printing are as follows.

  (1) Density of base paper: measured according to JIS P8118.

(2) Slip-off resistance: Offset rotary printing press (4 colors: B2T600 manufactured by Toshiba) using offset rotary printing ink (Toyo Ink Mfg. Co., Ltd. LeoX SOY M), printing speed of 500 rpm, paper on drying Printing was performed at a temperature of 110 ° C., and immediately after that, a crease was made in parallel with the paper passing direction by a folding machine attached to the printing machine, and further staple binding was performed. Thereafter, sensory evaluation was conducted on the difficulty of dropping the page when 10 monitors pulled the center page.
◎: Very good, ○: Good, △: Slightly inferior, ×: Inferior (3) Surface strength: Ink for offset printing (manufactured by Toyo Ink Manufacturing Co., Ltd.): TK mark V617) was used, and single-sided printing was performed at a constant ink amount of 0.4 cc, and the degree of smearing on the paper surface was evaluated. The case where no smear occurred was marked with ◎, the case where scarcely occurred was marked with ◯, the matter where it occurred was marked with △, and the mark with marked occurrence was marked with ×.

  (4) Blister resistance: Using a RI-I type printer (Ming Seisakusho), using offset printing ink (manufactured by Toyo Ink Manufacturing Co., Ltd .: TK Mark V617), printing on both sides with a constant ink amount of 0.8 cc Then, after conditioning all day and night (23 ° C., 50% RH), the test piece was immersed in a constant temperature oil bath set at a temperature of 140 ° C., and the occurrence of blisters was visually determined. The case where no blisters occurred was marked with ◎, the case where almost no blisters occurred, the case where the blisters occurred, Δ, and the case where the blisters occurred markedly.

  (5) High-speed operability: At an operation speed of 1300 m / min, the boiling, streak generation, and the degree of sheet breakage in a size press were comprehensively evaluated. A sample having very good operability was marked with ◎, a sample with good operability within the allowable range ◯, a sample with poor operability and unacceptable Δ, and a sample with difficult operation.

<Making paper>
The composition of the pulp is 30% hardwood chemical pulp, 10% softwood chemical pulp, 60% softwood thermomechanical pulp. The strength was 0.5% to pulp, 11% calcium carbonate was blended as filler, and a sulfuric acid band was added to adjust the pH to 7.9. Using this stock, paper is made with a twin-wire on-top paper machine at a paper making speed of 1300 m / min. A starch-based aqueous solution (solid content concentration of 15%) consisting of 100 parts of oxidized starch is applied to a plain rod with a diameter of 40 mm. With a used rod metering size press coater, coating was applied to both sides so that the solid content per side was 0.8 g / m ² and dried to obtain a base paper for coating having a basis weight of 56.6 g / m ² .

<Pigment coating>
To 100 parts of pigment containing 50 parts of heavy calcium carbonate (Fimatech FMT-97, volume average particle size: 0.6 μm) and kaolin (Kamin Hydragloss, volume average particle size: 0.2 μm) Then, 2 parts of oxidized starch and 9 parts of carboxy-modified styrene / butadiene copolymer latex were mixed as an adhesive to make 11 parts, thereby preparing a pigment coating solution having a solid content concentration of 64%. This coating solution is applied to the coating base paper obtained by the above method on both sides with a short dwell time application type blade coater so that the coating amount is 15 g / m ² per side and dried. did.

<Surface treatment>
The coated paper obtained by the above method was calendered with a super calender at a heat roll temperature of 80 ° C. and a treatment linear pressure of 150 kM / m.

  In this example, the paper making speed, coating speed, and surface treatment (calendar) speed were all 1300 m / min.

  In Example 1, a coated paper for printing was obtained in the same manner as in Example 1 except that the pulp composition was 90% hardwood chemical pulp and 10% softwood chemical pulp.

  In Example 1, a coated paper for printing was obtained in the same manner as in Example 1, except that the pulp composition was 10% hardwood chemical pulp, 10% softwood chemical pulp, and 80% softwood thermomechanical pulp.

  In Example 1, a coated paper for printing was obtained in the same manner as in Example 1 except that the solid content concentration of the oxidized starch aqueous solution used in the size press was changed to 12%.

  In Example 1, a coated paper for printing was obtained in the same manner as in Example 1 except that the solid content concentration of the oxidized starch aqueous solution used in the size press was changed to 18%.

  In Example 1, a coated paper for printing was obtained in the same manner as in Example 1 except that the type of starch used in the size press was changed from oxidized starch to hydroxyethyl etherified starch.

  In Example 1, the coated paper for printing was obtained by the same method as Example 1 except having changed the softwood thermomechanical pulp used for the pulp into the hardwood thermomechanical pulp.

[Comparative Example 1]
In Example 1, a coated paper for printing was obtained in the same manner as in Example 1 except that the solid content concentration of the oxidized starch aqueous solution used in the size press was changed to 10%.

[Comparative Example 2]
In Example 1, a coated paper for printing was obtained in the same manner as in Example 1 except that the solid content concentration of the oxidized starch aqueous solution used in the size press was changed to 22%.

[Comparative Example 3]
In Example 1, the rod in the rod metering size press coater was changed from a plain rod without grooves to a grooved rod with a groove width of 0.2 mm, and the solid content concentration of the starch aqueous solution used for the size press was set to 8 A coated paper for printing was obtained in the same manner as in Example 1 except that the percentage was changed to%.

[Comparative Example 4]
In Example 1, the coated paper for printing was obtained by the same method as Example 1 except having changed the size press system from the rod metalling press coater to the gate roll coater.

[Comparative Example 5]
In Example 1, the same method as in Example 1 except that the size press method was changed from the rod metalling method to a two-roll pound method, and the solid content concentration of the starch aqueous solution used in the size press was changed to 4%. A coated paper for printing was obtained.

[Comparative Example 6]
In Example 1, a coated paper for printing was obtained in the same manner as in Example 1 except that size pressing was not performed.

Tables 1 and 2 show the evaluation results. As is apparent from the table, even when a relatively low density base paper of 0.4 to 0.7 g / cm ³ is used, the solid content concentration of the starch aqueous solution in the size press is set to 12 to 20%, and the plain rod is By coating with the rod metering size press method used, it is possible to produce coated paper with stable operability with low density but also printing quality such as crease resistance, surface strength and blister resistance. It was confirmed that it was possible.

Claims (6)

In a method for producing a coated paper for printing, in which at least one coating layer containing a pigment and an adhesive is applied to a base paper, a starch-based aqueous solution having a solid content concentration of 12 to 20% by weight is used for a plain rod. After applying and drying with a size press device using a rod metalling method , including applying a coating liquid containing a pigment and an adhesive ,
The basis weight of the coated paper is 70~110g / m ^2,
The coating amount of the coating layer containing the pigment and the adhesive is 12 to 20 g / m ² per side ,
Density of the base paper is 0.4 to 0.8 g / cm ^3, the manufacturing method of the coated paper for printing. The manufacturing method of the coated paper for printing of Claim 1 whose density of coated paper is 0.8-1.1 g / cm < ³ >. The manufacturing method of the coating paper for printing of Claim 1 or 2 including performing the coating of the coating liquid containing the said pigment and adhesive agent using a blade coater . The method for producing a coated paper for printing according to any one of claims 1 to 3 , wherein the starch is hydroxyethyl etherified starch. It said diameter plane rod is 30 to 50 mm, the production method of the coated printing paper according to any one of claims 1 to 4. The size operating speed of the press device, characterized in that it is 1200 m / min or more, the production method of the coated printing paper according to any one of claims 1 to 5.