JP5798182B2 - Coated paper and method for producing the same - Google Patents

Description

  The present invention relates to a coated paper and a method for producing the coated paper. In particular, the present invention relates to a coated paper containing a low-viscosity polymer compound as an adhesive and a method for producing the coated paper.

  In general, when a coated paper is produced, a coating layer mainly composed of a pigment and an adhesive for binding the pigment is formed in order to improve printability. Mainly petroleum-based from the viewpoints of good paint fluidity as an adhesive, good coating suitability in a coating device, and easy imparting of printing surface strength as coated paper quality Adhesives derived from these synthetic materials are used.

  However, in recent years, not only petroleum-based synthetic materials but also materials that are inexpensive and excellent in biodegradability are attracting attention due to cost reduction and increased environmental awareness. Among them, an adhesive using a starch-based material as a raw material has attracted attention.

JP 2010-84311 A

  However, when a starch-based material is highly blended in the paint (pigment coating liquid), the viscosity of the paint is remarkably increased, and the operability and coating suitability are deteriorated. Even if the viscosity is adjusted by dilution of the paint, the water content increases, so the load of the drying process after coating increases, and there is an adverse effect on productivity such as a decrease in coating speed. In addition, even if the coating speed is reduced, the coating concentration is low and the water retention of the coating is reduced. Therefore, the penetration of the coating into the base paper is large, and the glossiness of the white paper and the surface strength are reduced. Quality deterioration is inevitable.

  In view of such circumstances, the object of the present invention is to search for starch-based adhesives that can improve the white paper glossiness and surface strength of coated paper without significantly increasing the viscosity of the paint even when highly blended with the paint. The aim is to develop a technology for producing high-quality coated paper with high operability.

  As a result of diligent investigations to solve the above problems, when an aqueous slurry containing starch-based polymer is cooked, it is not the maximum viscosity at the time of cooking or the minimum viscosity when the viscosity drops after that, but for a certain time from the start of cooking. It has been found that when a starch-based polymer having a low viscosity after the process is used as an adhesive for the coating layer of the coated paper, a coated paper excellent in surface gloss and surface strength can be produced, and the present invention has been completed. It was.

Although this invention is not limited to this, The following invention is included.
(1) A coated paper having a pigment coating layer containing a pigment and an adhesive on a base paper, and a starch-based polymer slurry having a solid content concentration of 35% by weight is subjected to Rapid Visco Analyzer (RVA) The temperature is raised to 98 ° C in 5 minutes from 0 to 5 minutes, held at 98 ° C for 4 minutes to 5-9 minutes, lowered to 50 ° C in 3 minutes from 9 to 12 minutes, 4 to 16/16 The above coated paper containing a starch polymer having a viscosity of 700 mPa · s or less after 16 minutes from the start of cooking as the adhesive when steamed under the steaming condition of maintaining at 50 ° C. for a minute.
(2) The coated paper according to (1), wherein no copolymer latex is used as the adhesive, or 4 parts by weight or less of the copolymer latex is used with respect to 100 parts by weight of the pigment.
(3) The coated paper according to (1) or (2), wherein the starch polymer compound is white dextrin.
(4) The coated paper according to any one of (1) to (3), wherein the pigment contains calcium carbonate.
(5) The coated paper according to any one of (1) to (4), wherein the pigment coating layer contains 5 to 50 parts by weight of a starch polymer per 100 parts by weight of the pigment.
(6) A method for producing a coated paper having a pigment coating layer containing a pigment and an adhesive on a base paper, wherein a starch-based polymer slurry having a solid content concentration of 35% by weight is subjected to Rapid Visco Analyzer (Rapid Visco Analyzer). : RVA), the temperature was raised to 98 ° C. in 5 minutes from 0 to 5 minutes, kept at 98 ° C. for 4 minutes from 5 to 9 minutes, lowered to 50 ° C. in 3 minutes from 9 to 12 minutes, 12 to 16 For 4 minutes, when steamed under the steaming condition of maintaining at 50 ° C., a coating solution containing a starch polymer and a pigment having a viscosity of 700 mPa · s or less after 16 minutes from the start of cooking is applied onto the base paper. The above method, comprising working.

  The coated paper of the present invention uses a specific starch-derived polymer compound as an adhesive, and the fluidity of the coating liquid is good. When the fluidity is improved, handling of the coating liquid becomes easy and the coating suitability is improved, so that the operation efficiency is improved. In addition, since the concentration of the coating liquid can be increased and water retention is improved, it prevents the coating liquid from penetrating into the base paper, thereby improving the glossiness of the resulting coated paper and improving the surface strength. The quality of various coated papers is improved.

FIG. 1 is a graph showing the results of analyzing various starch polymers with a rapid visco analyzer.

  The coated paper of the present invention is not particularly limited as long as it is a coated paper in which a pigment coating layer containing a white pigment and an adhesive is provided on the base paper, and printing used for offset printing, gravure printing, letterpress printing, etc. Of course, white paperboard having a pigment coating layer on the paperboard base paper may be used.

  In the coated paper of the present invention, one or more pigment coated layers containing a pigment are provided on a base paper. On the base paper, a coating solution (size press solution) containing no pigment may be applied or not.

  The ash content in the coated paper of the present invention is preferably 30% by weight or more. In the case of coated paper for printing, it is preferable to increase the opacity by increasing the ash content.

In the present invention, a pigment coating layer containing a pigment, an adhesive (binder), and water is mainly used to provide a pigment coating layer. As an adhesive (binder), starch having a specific viscosity is used. Add the derived polymer compound. The starch-derived polymer compound of the present invention has a particularly low viscosity after elapse of a certain time after cooking, so that the viscosity of the pigment coating liquid is not greatly increased even when blended in the pigment coating liquid. The density can be increased, thereby improving the print quality of the coated paper. That is, since the coating of the base paper is suppressed and the effective coating layer is increased, the quality of various coated papers such as improvement of glossiness and surface strength is improved.

  In the present invention, a starch-derived polymer compound is used as the adhesive. As the starch-derived polymer compound, starches including various processed starches and dextrins obtained by hydrolyzing starch can be preferably used. Starch refers to a mixture composed of amylose and amylopectin, and generally the mixing ratio varies depending on the plant that is the raw material of starch.

  The starch-derived polymer compound of the present invention is a starch-derived polymer compound having a slurry viscosity of 700 mPa · s or less after steaming under certain conditions.

  When starch compounds are suspended in water and heated, the starch granules absorb water and gradually expand. When the heating is continued, the starch granules eventually disintegrate and change into a gel. This phenomenon is called gelatinization. At this time, the starch suspension becomes gradually transparent from the cloudy state and rapidly increases in viscosity. The viscosity becomes maximum when the particles absorb water to the maximum extent, and the viscosity decreases due to the collapse of the particles. In the present invention, after the viscosity is maximized by cooking, the one having a certain range of viscosity when it is allowed to stand at a reduced temperature is used.

  When the starch-based polymer compound is contained in the coating liquid, heating for dissolving the polymer compound is required. Therefore, the viscosity of the slurry after cooking under certain conditions is important.

  Since the starch-derived polymer compound of the present invention has a low viscosity of the slurry after cooking, the concentration of the slurry can be increased.

  Also, for example, cold water-soluble starch represented by pregelatinized starch has a low slurry viscosity, but these cold water-soluble starches are treated so that they are soluble in cold water, and dextrin and the like are more surface strength. Highly advantageous. Therefore, the starch-based polymer compound of the present invention preferably has a solubility in water at 20 ° C. of less than 20%.

  The behavior of such a starch polymer can be measured using a measuring instrument called Rapid Visco Analyzer (RVA, model RVA-4, manufactured by New Port Scientific). In the present invention, when a starch polymer slurry having a concentration of 35% by weight is cooked under the following cooking conditions, a starch polymer having a viscosity at 50 ° C. after 16 minutes from the start of cooking is 700 mPa · s or less. . In one embodiment of the present invention, a starch-based polymer is used as an adhesive for the pigment coating layer, and the adhesive strength as a binder is manifested by cooking (cooking) the slurry.

<RVA viscosity measurement conditions>
The paddle is rotated under the following conditions, the torque applied to the stirring paddle is measured, and the viscosity is calculated.
Stirring conditions : 10 seconds after starting measurement: 960 rpm
-Then: 160rpm
Steaming conditions・ 0 to 5 minutes: raised to 98 ° C. in 5 minutes ・ 5 to 9 minutes: held at 98 ° C. ・ 9 to 12 minutes: lowered to 50 ° C. in 3 minutes ・ 12 to 16 minutes: at 50 ° C. Retention

  The viscosity of the starch-based polymer compound measured as described above at the stage of holding at 50 ° C. after 16 minutes after cooking is 700 mPa · s or less, more preferably 500 mPa · s or less, most preferably 300 mPa · s or less. It is.

  Moreover, the starch-based polymer of the present invention preferably has a maximum viscosity of 1,500 mPa · s or less, preferably 1300 mPa · s or less, when the viscosity is measured under the above conditions using RVA. More preferably, it is more preferably 1000 mPa · s or less. When the maximum viscosity at the time of gelatinization is in such a range, handling is easy, and an excessive increase in viscosity does not occur when blended in a coating solution.

  The starch-derived polymer compound of the present invention is not particularly limited as long as it has the above viscosity, and the modification method, the raw material type, and the like are also free. Examples of modified starch, modified starch, and the like include oxidized starch, hydroxyesterified starch (HES), phosphate starch, esterified starch, and dextrin. Of these, dextrin is preferred because the fluidity is further improved (low viscosity) when blended in a paint. Moreover, as a preferable raw material of the starch polymer used in the present invention, corn, potato, tapioca and the like can be mentioned, and waxy corn (waxy corn) and tapioca are particularly preferable.

  Examples of the starch polymer satisfying the viscosity of the present invention include low-viscosity hydroxyethyl starch (HES), oxidized acetylated tapioca starch, and dextrin. These starch polymers are low in viscosity, stable in viscosity, and excellent in strength.

  In the present invention, since the viscosity is low and the viscosity stability is high, dextrin, particularly roasted dextrin is preferable as the adhesive. Dextrin is a general term for starch-based polymers obtained by hydrolyzing starch, and α-glucose is polymerized by glycosidic bonds, and is also called glue. Although ordinary starch has a large molecular weight, dextrin is an intermediate product produced in the hydrolysis process of starch, and has a molecular weight of about an oligomer (one having about 20 to 20 glucose bound). The roasted dextrin is a dextrin produced by adding an acid and baking with dry heat, and there are types such as white dextrin, yellow dextrin, and British gum. In the present invention, it is particularly preferable to use white dextrin. When the white dextrin is further hydrolyzed, it becomes a so-called yellow dextrin. However, since the yellow dextrin has low stability and the pigment coating layer may be colored, the use of white dextrin is preferred in the present invention.

  The starch-derived polymer compound of the present invention has good fluidity when blended in a coating solution. When fluidity is improved, it becomes possible to increase the concentration of the coating liquid, suppress the penetration of the coating liquid, and increase the effective coating layer, thereby improving the gloss development, whiteness, surface strength, etc. Improved coated paper quality.

  In a preferred embodiment, the amount of the starch-derived polymer compound of the present invention is 5 to 50 parts by weight, more preferably 5 to 30 parts by weight per 100 parts by weight of the pigment.

  In the present invention, as the adhesive, only the starch-derived polymer compound can be used, but in addition to the starch-derived polymer compound, an adhesive conventionally used for coated paper is used. It can also be used together. Examples of adhesives other than the above-mentioned starch-derived polymer compounds include styrene / butadiene, styrene / acryl, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, Synthetic adhesives such as polymers, polyvinyl alcohol, maleic anhydride copolymers, and acrylic acid / methyl methacrylate copolymers; proteins such as casein, soy protein, and synthetic proteins; other than the above starch-derived polymer compounds Oxidized starch, positive starch, urea phosphate esterified starch, etherified starch such as hydroxyethyl etherified starch, starch such as dextrin; normal coated paper such as carboxymethylcellulose, hydroxyethylcellulose, and cellulose derivatives such as hydroxymethylcellulose An adhesive is included. One or more types of adhesives can be appropriately selected and used. In the present invention, it is preferable to use a latex having a different characteristic from that of the starch polymer compound as an adhesive, and in that case, it is preferable to use more starch polymer compound than the latex. Although both advantages of the starch compound and latex can be obtained by the combined use, it is preferable to increase the amount of the starch polymer compound used in order to exert the effect of the present invention. When a starch polymer compound and latex are used in combination as an adhesive, the latex content of the entire adhesive is preferably less than 50% by weight.

  Further, copolymer latex is known as an adhesive used in the pigment coating layer. In a preferred embodiment of the present invention, the copolymer latex is not used as the adhesive, or the amount of the copolymer latex used. Is 4 parts by weight or less with respect to 100 parts by weight of the pigment. Moreover, it is preferable when the usage-amount of copolymer latex shall be 2.5 weight part or less. By not using or reducing the amount of copolymer latex, there are advantages such as prevention of dirt on the backing roll, improvement of blister resistance, and cost reduction by reducing the use of expensive copolymer latex. .

  In the present invention, the total amount of the adhesive in the coating liquid is not particularly limited, but is preferably 5 to 50 parts by weight, more preferably about 5 to 30 parts by weight, and further 5 to 12 parts by weight per 100 parts by weight of the pigment. Is preferred. When the starch-derived polymer compound and other adhesives are used in combination as the adhesive, the total amount is preferably within the above range.

  In the present invention, the method for preparing the coating liquid is not particularly limited and can be appropriately adjusted depending on the type of coater. When a blade type coater is used, the solid content concentration of the coating liquid is preferably 40 to 70% by weight, more preferably 60 to 70% by weight. The viscosity of the coating liquid is preferably 500 to 3500 mPa · s, more preferably 1000 to 3000 mPa · s, according to JIS K7117-1 B-type viscometer.

  In the present invention, various auxiliary agents blended in ordinary pigments for coated paper, such as dispersants, thickeners, water retention agents, antifoaming agents, water resistance agents, and colorants, can be used as necessary. .

Coating pigment The pigment (white pigment) used in the coating layer of the present invention is not particularly limited, and those conventionally used for coated paper can be used, for example, kaolin, clay, engineered kaolin. , 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 solid pigments, solid type, hollow type Or, an organic pigment such as a core-shell type can be used alone or in admixture of two or more. In addition, as a kind of pigment, heavy calcium carbonate and light calcium carbonate are preferable from the viewpoint of a low binder requirement and improving surface strength with a small amount of adhesive, and high whiteness, and also improve opacity. From the viewpoint, light calcium carbonate having a uniform particle diameter and shape is particularly preferable. This is because the bulky coating layer structure scatters light efficiently.

  When blending calcium carbonate in the coating liquid, the light calcium carbonate or heavy calcium carbonate, or the combined content thereof is preferably 50 parts by weight or more per 100 parts by weight of pigment, more preferably 70 parts by weight or more, 80 weight or more is more preferable. Further, from the viewpoint of forming a uniform coating layer on the base paper, the average particle size is preferably 0.2 to 5 μm as measured by a laser diffraction type particle size distribution analyzer such as Mastersizer S manufactured by Malvern. 2 to 3 μm is more preferable.

In the present invention, any coater that is usually used may be used. An on-machine coater or an off-machine coater may be used, and if it is an on-machine coater, a roll coater such as a size press coater, a gate roll coater, a rod metering size press coater, a bill blade coater, a blade metering size press coater, a short dwell blade A coater such as a coater or a jet fountain blade coater can be used. The coating speed is not particularly limited, but with the current technology, a blade coater is preferably 500 to 1800 m / min, and a size press coater is preferably 500 to 2000 m / min.

  In the present invention, the method for drying the wet coating layer is not limited, and various methods such as a steam superheated cylinder, a heated hot air air dryer, a gas heater dryer, an electric heater dryer, and an infrared heater dryer may be used alone or in combination. it can.

Although the coating amount of the coating liquid in this invention can be suitably selected according to a use, generally it is 2-13 g / m < ² > in solid content per single side | surface.

  Although the density | concentration of the coating liquid of this invention is not specifically limited, When printing quality is considered, about 60 weight%-about 75 weight% are preferable. The viscosity of the coating liquid of the present invention is preferably about 2000 mPa · s to 3000 mPa · s from the viewpoint of operability.

Base Paper The coated paper of the present invention has at least a base paper layer. A base paper can be manufactured by a well-known method, for example, a paper-making raw material (paper material) can be made in a wire part, and then it can be used for a press part and a pre-dryer part to manufacture a base paper. The base paper used in the present invention may be single-layer paper or multi-layer paper, but when producing white paperboard, it is preferable to use multi-layer paper. The method for producing the base paper of the present invention is not particularly limited, and can be performed by a known method using known raw materials. The base paper used in the present invention is not particularly limited, except for commonly used high-quality paper, medium-quality paper, renewal paper, machine-coated paper, art paper, cast-coated paper, synthetic paper, resin-coated paper, plastic film, etc. Can be used without

Although the basic weight of the base paper of this invention is not specifically limited, Although it can select suitably according to a use, it can be set as 35-150 g / m < ² >, for example, and it is good also as 40-100 g / m < ² >.

Raw material pulp Chemical pulp can be used as a pulp raw material used for the base paper of the present invention. In addition to chemical pulp, various pulps can be used depending on the application, for example, deinked pulp (DIP), groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermo. Examples include mechanical pulp (CTMP), chemi-ground pulp (CGP), and semi-chemical pulp (SCP). As the deinked pulp, it is possible to use deinked pulp made from selected waste paper such as high quality paper, medium quality paper, lower grade paper, newspaper, flyers, magazines, etc., or unselected waste paper mixed with these.

Filler In the present invention, a known filler can be arbitrarily used as a base paper filler, such as heavy calcium carbonate, light calcium carbonate, clay, silica, light calcium carbonate-silica composite, kaolin, calcined kaolin, deramikaolin, Amorphous produced by neutralization of white carbon, talc, magnesium carbonate, barium carbonate, barium sulfate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, titanium oxide, sodium silicate Inorganic fillers such as porous silica and organic fillers such as urea-formalin resin, melamine resin, polystyrene resin and phenol resin can be used alone or in combination. Among these, heavy calcium carbonate and light calcium carbonate, which are typical fillers for neutral papermaking and alkaline papermaking, are preferably used to improve opacity. The filler content in the paper is not particularly limited, but is preferably 1 to 40% by weight, and more preferably 10 to 35% by weight.

  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, various paper strength enhancers and internal additive sizing agents, etc. Can be used. Examples of the dry paper strength improver include polyacrylamide and cationized starch, and examples of the wet paper strength improver include polyamidoamine epichlorohydrin. These chemicals are added within a range that does not affect the formation and operability. Examples of neutral sizing agents include alkyl ketene dimers, alkenyl succinic anhydrides, and neutral rosin sizing agents. Furthermore, dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be added as necessary.

  The paper making method of the base paper in the present invention is not particularly limited, and a long paper machine including a top wire, an on-top former, a gap former, a round paper machine, a long paper machine and a round paper machine are used in combination. It can be performed using a paperboard machine, a Yankee dryer machine or the like. The pH during papermaking may be acidic, neutral or alkaline, but neutral or alkaline is preferred. The paper making speed is not particularly limited.

Clear coating The coated paper of the present invention may have a clear (transparent) coating layer on one side or both sides of the base paper described above. By applying clear coating on the base paper, the surface strength and smoothness of the base paper can be improved, and the coating property when applying pigment can be improved. In this invention, you may contain the high molecular compound derived from the starch of this invention as a binder in a clear coating layer. The amount of clear coating is preferably 0.1 to 4.0 g / m ² , more preferably 0.5 to 2.5 g / m ² in terms of solid content on one side.

  In the present invention, the clear coating means, for example, various starches such as starch and oxidized starch using a coater (coating machine) such as a size press, a gate roll coater, a pre-metering size press, a curtain coater, and a spray coater. It means that a coating liquid (surface treatment liquid) mainly composed of a water-soluble polymer such as polyacrylamide or polyvinyl alcohol is applied (size press) on a base paper.

Pre-calendar treatment In the present invention, pre-calendar processing is performed on the base paper before coating by online soft calendar, online chilled calendar, etc., and the base paper is smoothed in advance, so that the coating layer after coating is made uniform This is preferable. In this case, the treatment linear pressure is preferably 30 to 100 kN / m, more preferably 50 to 100 kN / m. Moreover, the moisture content of the base paper at the time of pre-calendering is also important, and the moisture content is preferably 3 to 5%.

Surface Treatment In the present invention, the paper produced as described above is subjected to a surface treatment as necessary. For smoothing processing, a smoothing processing device such as a normal super calendar, gloss calendar, soft calendar, thermal calendar, shoe calendar, or the like can be used. The smoothing apparatus is appropriately used on-machine or off-machine, and the form of the pressure device, the number of pressure nips, heating, and the like are also adjusted as appropriate. In a preferred embodiment, the coated paper of the present invention can be surface-treated with a calendar such as a super calender or a high temperature soft nip calender. By the surface treatment, the smoothness and glossiness of the coated paper can be improved. In the present invention, soft nip calendering is preferred. Both softness and opacity are improved by soft nip calendering. In the soft nip calendering process, the linear pressure at the surface temperature of the metal roll of 20 ° C. to 60 ° C. is 30 to 60 kN / m, more preferably 40 to 60 kN / m. Moreover, if the surface temperature of the metal roll is a high temperature soft nip calender treatment of 40 ° C. to 250 ° C., the linear pressure is 60 to 400 kN / m, preferably 150 to 300 kN / m, more preferably 100 to 350 kN / m. is there. Increasing the temperature improves the gloss and smoothness of the coated paper surface.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. In the present specification, “%”, “part”, and the like are based on weight, and the numerical range is described as including the end points.

[Evaluation method]
(1) Surface strength After printing using a printing ink (Toyo Ink High Unity M) using a RI-I type printing machine (Meiji Seisakusho), manually transfer the print marks on the transfer roll onto the transfer paper. The degree of picking was visually evaluated. The evaluation criteria are as follows.
◎ = Not generated at all, ○ = Not generated at all, Δ = Generated, × = Significantly generated (2) Blank paper glossiness Measured according to JIS P-8142 at an angle of 75 degrees.
(3) Glossiness of printing Printed at a printing speed of 8000 sheets / minute in the order of black, indigo, red, and yellow using a printing ink (Hi-Unity M manufactured by Toyo Ink) on a Roland flat-format printing machine (4 colors). The three-color (indigo, red, yellow) solid print part of the obtained printed matter was measured at an angle of 75 degrees according to JIS P-8142.
(4) PPS roughness Measured according to JIS P-8151. The clamping pressure was 1 MPa and hard backing.
(5) Backing roll dirt After operating continuously for 72 hours, the dirt state of the roll was visually evaluated.
◎ = Backing roll dirt is not generated, ○ = Backing roll dirt is slightly generated, Δ = Backing roll dirt is considerably generated, X = Backing roll dirt is remarkably generated (6) Blister resistance RI-I type printing press (Meiji Seisakusho), offset printing ink (manufactured by Toyo Ink Manufacturing Co., Ltd .: TK Mark V617) was used. It was immersed in a constant temperature oil bath set at 140 ° C., and the occurrence of blisters was visually judged.
◎ = Not generated at all, ○ = Not generated at all, △ = Generated, × = Significantly generated

Example 1
Add light calcium carbonate as a filler to a pulp slurry consisting of 60 parts of waste paper pulp, 30 parts of NBKP, and 10 parts of LBKP so that the ash content in the paper is 13%, and add 3 parts of cationized starch as an internal paper strength agent. The paper stock was adjusted.

Using this stock, paper was made on a gap-former type paper machine of roll and blade former type at a paper making speed of 1500 m / min, and two tandem shoe presses (press linear pressure 1000 kN / m, second one) The wet paper was squeezed and dried using a transfer belt in contact with the wire surface side of the paper to obtain 45.6 g / m ² of medium-quality coated base paper.

  Next, heavy calcium carbonate is used as a pigment, white dextrin (Stabilys A030, Roquette, Inc .: RVA viscosity at 160 rpm after cooking, that is, 16 minutes after cooking is 374 mPa · s) and carboxy-modified styrene · A butadiene copolymer latex was blended to prepare a coating solution having a solid content concentration of 68.5%. To 100 parts of heavy calcium carbonate, 6.0 parts of white dextrin and 4.0 parts of copolymer latex were blended.

Using this coating solution, the coating solution was continuously applied on both sides with a jet fountain blade coater so that the coating amount was 7.0 g / m ² per side of the base paper, and dried.

  Subsequently, a 2-roll / 6-stack soft calender having an elastic roll with a shore hardness of D94 ° was used in the finishing process, each metal roll surface temperature was 130 ° C., and each nip line pressure was 250 kN / m. Processed.

  Since papermaking, coating, and calendaring were performed continuously, the coating speed and calendar speed were also 1500 m / min.

Example 2
A coated paper for printing was produced in the same manner as in Example 1 except that the amount of white dextrin was 8 parts by weight.

Example 3
Except that 7 parts by weight of white dextrin (Stabilys A040, Roquette: steamed, that is, RVA viscosity at 160 rpm after cooking for 16 minutes) is used as the starch polymer, the same as in Example 1. A coated paper for printing was produced.

Example 4
A coated paper for printing was produced in the same manner as in Example 3 except that the amount of white dextrin was changed to 10 parts by weight.

Example 5
A coated paper for printing was produced in the same manner as in Example 3, except that the carboxy-modified styrene / butadiene copolymer latex described in Example 1 was used in combination as the adhesive used in the pigment coating solution.

Example 6
As an adhesive used in the pigment coating liquid, 6 parts by weight of white dextrin (Stabilys A040, Roquette: steamed, that is, RVA viscosity at 160 rpm after 16 minutes of cooking at 97 rpm), carboxy-modified styrene / butadiene copolymer A coated paper for printing was produced in the same manner as in Example 5 except that the amount of latex was changed to 2 parts by weight.

Comparative Example 1
Example 1 except that 6 parts by weight of hydroxyethylated starch (Ethylex 2005, Tate & Lyle: steamed, ie, RVA viscosity at 160 rpm after 16 minutes of steaming of 1486 mPa · s) was used as the starch polymer. Thus, a coated paper for printing was produced.

Comparative Example 2
A coated paper for printing was produced in the same manner as in Comparative Example 1 except that the amount of the hydroxyethylated starch was 9 parts by weight.

Comparative Example 3
A coated paper for printing was produced in the same manner as in Example 1 except that only 10 parts by weight of carboxy-modified styrene / butadiene copolymer latex was used as the adhesive used in the pigment coating solution.

  Table 1 shows the results. As is apparent from Table 1, when a starch-based polymer having a viscosity of 700 mPa · s after 16 minutes of steaming is used as an adhesive, the white paper gloss and printing gloss are significantly improved as compared with the comparative example, and the surface smoothness. (PPS roughness) and surface strength were also improved.

Claims (8)

A coated paper having a pigment coating layer containing a pigment and an adhesive on a base paper,
The adhesive contains a starch-based polymer, and as the adhesive, a copolymer latex is not used, or a copolymer latex of 4 parts by weight or less is used with respect to 100 parts by weight of the pigment,
The starch polymer has a solubility in water at 20 ° C. of less than 20%, and a starch polymer slurry having a solid content of 35% by weight is converted to 0 using a Rapid Visco Analyzer (RVA). Increase to 98 ° C in 5 minutes to 5 minutes, hold at 98 ° C for 4 minutes to 5-9 minutes, decrease to 50 ° C in 3 minutes to 9-12 minutes, increase to 50 ° C for 4 minutes to 12-16 minutes when cooked in the cooking condition that the holding, the viscosity after cooking 16 minutes Ri der less 700 mPa · s,
The coated paper containing 50 parts by weight or more of calcium carbonate per 100 parts by weight of the pigment. The coated paper according to claim 1, wherein the starch polymer is a starch polymer made of waxy corn or tapioca.   The coated paper according to claim 1 or 2, wherein the starch-based polymer compound is white dextrin. The coating amount of the pigment coating layer is 2 to 13 g / m in solid content on one side. ² The coated paper according to any one of claims 1 to 3, wherein   The coated paper according to any one of claims 1 to 3, wherein the pigment coating layer contains 5 to 50 parts by weight of a starch polymer per 100 parts by weight of the pigment. The coated paper in any one of Claims 1-5 whose average particle diameter of the said calcium carbonate is 0.2-5 micrometers.   The coated paper according to claim 1, wherein 70 parts by weight or more of calcium carbonate is contained per 100 parts by weight of the pigment. A method for producing a coated paper having a pigment coating layer containing a pigment and an adhesive on a base paper,
Coating a base paper with a coating liquid containing an adhesive and a pigment,
The adhesive contains a starch-based polymer, and as the adhesive, a copolymer latex is not used, or a copolymer latex of 4 parts by weight or less is used with respect to 100 parts by weight of the pigment,
The starch polymer has a solubility in water at 20 ° C. of less than 20%, and a starch polymer slurry having a solid content of 35% by weight is converted to 0 using a Rapid Visco Analyzer (RVA). Increase to 98 ° C in 5 minutes to 5 minutes, hold at 98 ° C for 4 minutes to 5-9 minutes, decrease to 50 ° C in 3 minutes to 9-12 minutes, increase to 50 ° C for 4 minutes to 12-16 minutes when cooked in the cooking condition that the holding, the viscosity after cooking 16 minutes Ri der less 700 mPa · s,
The above method, wherein 50 parts by weight or more of calcium carbonate is contained per 100 parts by weight of the pigment.

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