JP2010013750A - Coated paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated paper having bulkiness, excellent white paper gloss and thick feeling, and high printability. <P>SOLUTION: The coated paper having at least two coated layers formed on a base paper is obtained by forming the coated layer free from a pigment and containing a cationized starch as an undercoat layer contacting the base paper, and forming the coated layer comprising the pigment and an adhesive as a topcoat layer on the undercoat layer. Preferably, the cationized starch is a cationized tapioca starch, and the cationized degree of the cationized tapioca starch is 0.010-0.040. Further preferably, the pigment for the topcoat layer contains &ge;30 pts.mass of kaoline clay having a 3-20 aspect ratio based on 100 pts.mass of the whole pigment. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a coated paper provided with two or more coating layers. More specifically, a coating layer containing a cationized starch is provided as an undercoat coating layer in contact with the base paper, and an overcoat coating layer comprising a pigment and an adhesive is provided on the undercoat coating layer. The present invention relates to a coated paper having excellent gloss and hand feeling and high printability.

  In the field of printing paper, there has been a demand for coated paper that is more bulky, has excellent white paper gloss and hand feeling, and has high printability.

  In order to improve the glossiness of the coated paper, the surface of the coated paper is flattened using a flattening facility such as a super calendar or soft calender, but pressure is applied to the coated paper during flattening. There was a problem that the bulk of the coated paper and the hand feeling decreased.

  In order to prevent the coated paper from being crushed during flattening, as a method of improving the bulk and hand feeling of the coated paper, before providing the pigment coating layer, an undercoat coating layer containing starch is provided, and the base paper is There is a way to make it hard to collapse. By applying the starch undercoating, it is possible to increase the linear pressure of the calendar, etc., to obtain a coated paper that is excellent in white paper gloss, excellent in paper gloss, hard to be crushed, and excellent in bulk and hand feeling. However, there is a need for a coated paper that is more bulky, has a hand feeling and is excellent in white gloss.

  In general, oxidized starch is used for the starch used in the undercoat coating layer. However, the oxidized starch easily sinks into the base paper, so that the coating layer is difficult to form, and the bulk and hand feeling are difficult. There was a problem. This is thought to be because the starch is absorbed into the base paper by capillary action, although both oxidized starch and pulp are anionic and easily repelled.

As a method for forming a starch coating layer on the surface of the base paper, the undercoat coating solution is more difficult to absorb by the base paper, and a method using cationic starch, which is a cationic starch, is known (Patent Document 1). ~ 3). When cationized starch is used, the ionic bond proceeds at the part where the cationic group of the cationized starch and the anionic group of the pulp are in contact with each other, and a starch immobilization layer is formed, making it difficult for starch to penetrate into the base paper. A coated paper with a bulky and hand-feeling can be obtained. However, it was not possible to obtain a coated paper having a sufficient bulkiness, hand feeling and white gloss simply by coating with cationized starch.
JP-A-6-57693 JP 2004-143612 A JP 2006-161216 A

  An object of the present invention is to provide a coated paper that is bulky, excellent in white paper gloss and hand feeling, and high in printability.

  The present invention is a coated paper provided with at least two coating layers on a base paper, wherein an undercoat coating layer in contact with the base paper is provided with a coating layer containing no cationized starch and containing no pigment. The present invention relates to a coated paper characterized in that a coating layer composed of a pigment and an adhesive is provided as a top coating layer on the coating layer.

  Preferably, the cationized starch is a cationized tapioca starch, and the cationized tapioca starch has a degree of cationization of 0.010 to 0.040.

  Preferably, 30 parts by mass or more of kaolin clay having an aspect ratio of 3 to 20 is contained as a pigment of the top coat layer with respect to 100 parts by mass of the total pigment.

  The coated paper of the present invention is a coated paper that is bulky, has excellent white paper gloss and hand feeling, and has high printability.

  First, the base paper which comprises the coated paper which concerns on this embodiment is demonstrated.

  The base paper should just be obtained by papermaking a normal raw material pulp. The raw material pulp is not particularly limited. For example, chemical pulp such as unbleached softwood pulp (NUKP), unbleached hardwood pulp (LUKP), bleached softwood pulp (NBKP), bleached hardwood pulp (LBKP), etc .; Stone Grand Pulp (SGP) ), Pressurized Stone Grand Pulp (PGW), Refiner Grand Pulp (RGP), Chemi Grand Pulp (CGP), Thermo Grand Pulp (TGP), Grand Pulp (GP), Thermo Mechanical Pulp (TMP), Chemi Thermo Mechanical Pulp ( CTMP), refiner mechanical pulp (RMP) and other mechanical pulp; magazine waste paper, leaflet waste paper, waste paper pulp manufactured from office waste paper, etc., waste paper pulp such as disaggregation / deinking / bleached waste paper pulp, etc. , Select one or more of these as appropriate, It can be used to adjust the focus.

  A filler conventionally used for papermaking can be added to the pulp as an internal filler. Examples of the filler include light calcium carbonate, clay, talc and the like. The blending amount of the filler is not particularly limited, and may be adjusted within the range of conventional coated paper, for example, about 3 to 20% by mass.

  In this embodiment, the slurry is blended with a base paper of a normal coated paper, such as a coagulant, a flocculant, a sizing agent, a paper strength enhancer, a paper thickness improver, and a yield improver, if necessary. Various additives can be internally added by appropriately adjusting the type and blending amount.

  Papermaking raw materials such as those mentioned above can be made in a wire part, and then subjected to a press part and a pre-dryer part to produce a base paper. Next, an undercoat coating solution described later is applied on the base paper by a coater part. After drying with an after dryer part, flattening with a pre-calender, and then applying a top coat liquid described later on the coater part on the base paper, drying with an after dryer part, a calendar part, The target coated paper can be obtained by using it in a reel part, a winder part or the like.

  In particular, as will be described later, the present invention is more effective when it is undercoated, dried by a dryer part and then flattened by a pre-calender.

  In addition, in the overcoating layer to be described later, it is difficult to improve the whiteness of the resulting coated paper because the overcoating is preferably performed with a coating liquid mainly composed of clay. Therefore, in order to further improve the whiteness of the target coated paper, the whiteness of the base paper is measured by a color analyzer (model number: color i5, manufactured by Macbeth Gretag), 70% or more, and further 75. % Or more is preferable. When the coated paper for printing is manufactured from such a base paper, the whiteness can be set to, for example, 77% or more as described later. When such a coated paper having a whiteness of 77% or more is used, for example, a high-quality printed material having a higher definition and a higher contrast can be obtained compared to a coated paper having a whiteness of less than 77%. It is done.

Although there is no particular limitation on the basis weight of the base paper, as will be described later, the basis weight of the target coated paper is preferably 30 to 100 g / m ^2. Usually, it is preferable to adjust so that it may become about 25-95 g / m < ² >.

<Undercoat>
Before providing an overcoating layer to be described later on one side or both sides of the base paper, an undercoating layer containing starch and not containing a pigment is preferably 0.2 to 1.0 g / m ² per side. Provide to be.

  Examples of the starch for undercoating that is generally used in papermaking applications include oxidized starch (cationic), carboxymethyl starch (anionic), hydroxyalkyl starch (nonionic), and phosphate starch (anionic). Modified starch is mentioned. However, when nonionic or anionic starch is used, it easily penetrates into the surface of an anionic base paper, so that the bulkiness and hand feeling are likely to be lowered. Therefore, in the present invention, a cationized starch is used which is easily ionically bonded to the anionic base paper surface, the starch in contact with the base paper is easily immobilized, and the starch is likely to remain on the surface. Commercially available products can be used as the cationized starch.

  The cationized starch in the present invention is a cationized starch obtained by reacting starch with a cationizing agent having an amino group, an imino group, an ammonium group or the like as a cationic group. That is, it is a cationized starch having a primary amino group, a secondary amino group, a tertiary amino group, or a quaternary ammonium group. As these cationized starches, commercially available products can be used.

  The degree of cationization of the cationized starch is preferably 0.010 to 0.040, and more preferably 0.015 to 0.030. If it is less than 0.010, the cationic property is low, so that starch easily penetrates into the base paper, and the bulkiness and hand feeling are inferior. In addition, since it is difficult to ionically bind to clay contained in the topcoat layer described later, the topcoat liquid is likely to penetrate into the undercoat layer, and the glossiness and printability of blank paper after the topcoat coating are reduced. Absent. If it exceeds 0.040, the cationic property is too strong, so it is easy to combine with the anionic group of the base paper and the anionic group of the top coating liquid, and the uniform coating of the undercoat coating liquid on the base paper and the top coating layer Uniform coating becomes difficult and printability may be reduced.

  The degree of cationization is calculated according to Kjeldahl analysis by calculating the nitrogen content from the content of nitrogen atoms in one molecule of cationized starch. From the nitrogen content and the weight average molecular weight, the cation group per glucose residue is calculated. The amount introduced was determined and used as the degree of cationization (degree of substitution). The weight average molecular weight was measured by size exclusion chromatography.

  The types of starch include, for example, untreated starch such as wheat starch, potato starch, corn starch, sweet potato starch, tapioca starch, sago starch, rice starch, waxy corn flour, corn starch with high amylose content, wheat flour, tapioca starch, corn flour And starch-containing materials such as rice flour. Among these, tapioca starch is preferable because it tends to remain on the surface of the base paper when it is cationized and coated on the surface of the base paper, compared with the above-mentioned other starches. In particular, in a cationized starch composed of tapioca, it is preferable that the degree of cationization is 0.010 to 0.040 because it tends to stay on the surface of the base paper in particular, and the bulk and hand feeling are easily improved.

  In addition to the above-mentioned cationized starch, the undercoat coating solution includes unmodified starch, modified starch other than cationized starch (starch derivatives such as oxidized starch, carboxymethyl starch, hydroxyalkyl starch, and phosphate starch), polyvinyl alcohol Polyacrylamide and the like can be contained within a range that does not impair the effects of the present invention.

The undercoat coating solution can be applied by various known methods in the size press process during the paper making process, but is preferably applied by a film transfer method. When coated by the film transfer method, a coating layer with a certain film thickness can be applied to the surface of the base paper, so compared to a method that forms a pound of coating liquid, such as a two-roll size press. It is characterized in that the penetration of the coating liquid into the inside of the base paper is suppressed and thin film coating is possible on the surface of the base paper. Therefore, when undercoating is applied by the film transfer method, even if the coating amount is as low as 0.2 to 1.0 g / m ² as in the present invention, the coating layer is uniformly applied to the base paper. It can be formed, and the flatness of the coated paper after top coating is increased, and the printability tends to be good. In particular, as in the present invention, when an anionic base paper is subjected to a cationic undercoat and an anionic topcoat layer described later is provided thereon, an undercoat coating solution in contact with the base paper, and an undercoat Due to the rapid immobilization of the topcoat coating solution in contact with the work layer, it is difficult to obtain a uniform coating. Therefore, by applying the undercoat layer to the undercoat layer by a film transfer method, uniform coatability is obtained not only in the undercoat layer but also in the overcoat layer, and the printability after the top coat is improved. Can be improved. When the blade coating method is applied, the resulting undercoat coating layer has high flatness, but when the coating amount is 0.2 to 1.0 g / m ² , the base paper surface cannot be sufficiently covered. This is not preferable because a part is generated and printability and blank gloss of the resulting coated paper may be lowered. In addition, it is not preferable to use a two-roll size press method because not only the coating liquid is excessively adhered, but also the hand feeling and bulk are easily lowered by impregnation with the coating liquid.

  As described above, when an undercoat coating solution containing cationized starch, particularly cationized starch made from tapioca, is coated with a film transfer method, it is not only excellent in bulk and gloss, but also has good printability. It is more preferable because a working paper can be obtained.

The concentration of the undercoat coating solution is not particularly limited, and may be appropriately adjusted so that the coating amount is preferably in the range of 0.2 to 1.0 g / m ² . For example, the concentration may be 2 to 10% by mass, and 3 to 5% by mass is preferable because a coated paper with a better hand feeling can be obtained. When the concentration is less than 2% by mass, water absorption to the base paper is likely to increase, so that it is easy to break the paper during undercoating. When the concentration exceeds 10% by mass, the coating amount becomes too large, and it is necessary to reduce the base weight and / or the top coating amount of the base paper, which is not preferable because hand feeling and printability are lowered.

The undercoat coating layer is coated such that the coating amount is one solid-coated amount per side, preferably 0.2 to 1.0 g / m ² , more preferably 0.6 to 0.8 g / m ^2. It is crafted. When the undercoat is not applied or the solid content is less than 0.2 g / m ² , not only sufficient printability cannot be obtained, but also bulkiness and hand feeling cannot be obtained. Moreover, when it exceeds 1.0 g / m ² , the coating amount is large and uniform coating becomes difficult, and when the undercoat coating layer is increased while the basis weight of the base paper is kept constant, In order to obtain coated paper, since it is necessary to reduce the coating amount of a top coat layer, since all are inferior to printability, it is unpreferable.

In particular, as in the present invention, when a coating layer containing starch is provided in the undercoating layer, the printability tends to be lower than that of the undercoating layer comprising a pigment and an adhesive, but the coating amount is preferably 0.8. Sufficient printability can be obtained by coating in the range of ^{2 to} 1.0 g / m ² , more preferably 0.6 to 0.8 g / m ² .

The undercoat coating layer preferably contains no pigment. When a pigment is included, there is an advantage that the smoothness and printability of the coated paper surface are good, and the printability is easily improved as described above, but the smoothness and printability of the surface contribute to the surface of the topcoat coating layer. The printability can be sufficiently covered by setting the undercoat coating layer to a coating amount of 0.2 to 1.0 g / m ² as described above and the topcoat coating to a coating amount as described later. Moreover, since a coating layer will become heavy when it contains a pigment and it becomes difficult to become bulky paper, it is preferable that a primer coating layer does not contain a pigment.

As described above, as a tapioca-derived starch, a cationized starch having a cationization degree of 0.010 to 0.040 is coated on the base paper with a coating amount of 0.2 to 1.0 g / m ² by a film transfer method. In particular, since a starch coating layer that easily stays on the surface of the base paper is obtained, the bulk and hand feeling of the resulting coated paper are likely to be improved. Moreover, it is preferable that the undercoat layer does not contain a pigment because a more bulky undercoat layer can be obtained.

<Pre-calendar>
The base paper after the undercoating is preferably subjected to a pre-calendering flattening before the topcoating because the flatness after the topcoating can be improved. As the precalender, it is preferable to use a soft calender in which a metal roll and an elastic roll are combined because the surface is highly improved. The pre-calendar can be performed in one stage or a combination of two or more stages as required. By flattening the surface of the base paper after undercoating by pre-calendering, the linear pressure on the calendar after topcoating can be reduced, and there is no need for excessive flattening. It is possible to improve the flatness of the surface of the coating layer after the top coating without lowering the thickness, and sufficient printability and hand feeling as a coated paper can be obtained. Further, when the surface of the base paper is flattened, the top coat layer can be applied uniformly, and the printability can be improved. The linear pressure of the pre-calender is preferably 10 to 80 kN / m, more preferably 10 to 50 kN / m. If it is less than 10 kN / m, flattening of the base paper after undercoating does not proceed, and if it exceeds 80 kN / m, the base paper is compressed more than necessary, so that the bulk and hand feeling are preferred. Absent.

<Topcoat coating>
An undercoating layer is formed, and an overcoating layer mainly composed of a pigment and an adhesive is provided on a base paper that has been preferably flattened with a pre-calender.

  There are no particular limitations on the type of pigment used for top coating, and those generally used as papermaking pigments can be used. Examples of the pigment include heavy calcium carbonate, light calcium carbonate, kaolin clay, delaminated kaolin, talc, white carbon, titanium dioxide, calcium sulfate, satin white, calcium sulfite, gypsum, barium sulfate, diatomaceous earth, magnesium carbonate, Inorganic pigments such as aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, magnesium oxide, bentonite, sericite, polystyrene resin fine particles, urea formalin resin fine particles, fine hollow particles, porous fine particles, etc. Special pigments such as organic pigments are exemplified, and one or more of them can be appropriately selected and blended.

  Among the above pigments, when kaolin clay is used, the glossiness and smoothness of the coated paper are easily improved, and the printability becomes better, which is preferable. When starch is used for the undercoat coating layer, the printability tends to be lower than when pigment is used, and in particular, when cationized starch is used for the undercoat coating layer, printability is obtained. Since it becomes difficult, the structure of a top coat layer becomes important. Therefore, it is preferable to add clay having better printability. By blending clay, the coated paper surface is easily flattened, so it is easy to obtain gloss, and it is not necessary to apply excessive linear pressure in the calendering process described later, and the pulp in the coated paper is less likely to be crushed. Thus, a coated paper having a good hand feeling can be obtained.

  In the present invention, it is preferable to use a clay having a particularly large aspect ratio in order to increase the bulkiness. As the clay, kaolin clay which has been conventionally used for papermaking can be used. The clay is generally plate-shaped, the surface portion of the plate is negatively charged, and the cross-sectional portion is positively charged. For this reason, when a plate-shaped clay with a small positive cross-section and a large negative surface and a high aspect ratio is used, it is easy to react ionized with the cationized starch contained in the undercoat coating layer, making it more bulky and hand-feeling This is preferable because a coated paper having a thickness can be obtained.

  The aspect ratio of kaolin clay is preferably 3-20, more preferably 5-10. When the aspect ratio is less than 3, the cation component is increased, so that the overcoating liquid easily penetrates into the undercoating layer, and the bulkiness and hand feeling are liable to decrease, which is not preferable. Exceeding 20 is not preferable because the clay tends to have a large particle size and the flatness of the surface of the topcoat layer tends to be lowered, and the glossiness of the blank paper and the printability are likely to be lowered.

  As described above, by applying clay having a high aspect ratio of 3 to 20 on the undercoat coating layer coated with the cationized starch, it becomes difficult for the overcoat coating layer to penetrate into the undercoat coating layer. It is preferable because a coated paper that is bulky and has a good hand feeling can be obtained.

  In particular, as described above, by using a clay having a high aspect ratio of 3 to 20 on an undercoat coating layer containing cationized starch made from tapioca, a coated paper having a higher bulk and excellent hand feeling is obtained. Obtainable. In addition, by applying the undercoat coating layer by a film transfer method, it is possible to apply the topcoat coating solution uniformly, so that the printability is easily improved, and further by applying a precalender treatment after the undercoat coating. Further, it is particularly preferable because the bulkiness, glossiness, and printability can be improved.

  The blending amount of clay is preferably 30% by mass or more, and more preferably 50% by mass or more, based on the total amount of pigment blended in the topcoat coating layer. If it is less than 30% by mass, the negative charge derived from clay is reduced, so that the overcoating liquid easily penetrates into the undercoating layer, and not only the bulkiness and hand feeling is lowered, but also the surface of the topcoating layer is flat. The printability tends to be difficult to improve because the printability also decreases.

  When the heavy calcium carbonate is used as the above-mentioned pigment, it is preferable because the whiteness is easily improved. However, the surface property after coating is deteriorated and the printability is inferior, so that the effect of the present invention is not impaired. It is preferable. In addition, heavy calcium carbonate has a poor charge on the particle surface, so it is difficult to ionize with the cationic undercoat layer, and the topcoat coating solution easily penetrates into the undercoat layer, resulting in a bulky and hand-feel. It's hard to be done. When heavy calcium carbonate is used, it is preferable to use clay and heavy calcium carbonate in combination. As a compounding quantity of heavy calcium carbonate, it is preferable to set it as 70 mass% or less with respect to the whole quantity of a pigment, and 50 mass% or less is more preferable.

  As an adhesive used for top coating, an adhesive that can be generally used for papermaking can be used in combination. For example, proteins such as casein and soybean protein; conjugated diene latex such as methyl methacrylate-butadiene copolymer latex, styrene-methyl methacrylate-butadiene copolymer latex, polymer latex of acrylate ester and / or methacrylate ester, or Acrylic latex such as copolymer latex, vinyl latex such as ethylene-vinyl acetate polymer latex, or alkali partial solubility obtained by modifying these various copolymer latexes with a functional group-containing monomer such as a carboxyl group or Latexes such as insoluble latex; synthetic resin adhesives such as polyvinyl alcohol, olefin-maleic anhydride resin, melamine resin, urea resin, urethane resin; oxidized starch, positive starch, esterified starch, dextrin, etc. Flour; carboxymethyl cellulose, and cellulose derivatives such as hydroxyethyl cellulose, are adhesives exemplified usually used for coated paper can be used in combination one or more from among the appropriately selected and. Of these, styrene-butadiene copolymer latex is particularly preferable because of its good thermal stability and good adhesion to the pigment.

  The blending ratio of the pigment and the adhesive in the coating liquid is preferably adjusted so that the adhesive is 3 to 10 parts by mass and further 4 to 8 parts by mass with respect to 100 parts by mass of the total pigment. Is more preferable. If the blending amount of the adhesive is less than 3 parts by mass, it is not preferable because the coating layer is likely to be taken off by a metal roll when performing a flattening process with a super calender. On the contrary, when the compounding amount of the adhesive exceeds 10 parts by mass, the adhesive is formed in the coating layer, the smoothness of the coating layer surface is lowered, the ink is difficult to transfer, and the printability is lowered. Therefore, it is not preferable.

  In addition to pigments and adhesives, the top coating liquid used in the present embodiment includes, for example, dust preventing agents, fluorescent dyes, fluorescent dye brighteners, antifoaming agents, mold release agents, colorants, water retention agents, and the like. Various auxiliary agents generally used in papermaking applications can be appropriately blended within a range not impairing the object of the present invention.

  There is no particular limitation on the method for preparing the topcoat coating solution, and the mixing ratio of pigments, adhesives, dust inhibitors, and various auxiliary agents as necessary is adjusted appropriately, and a uniform composition at an appropriate temperature. What is necessary is just to stir and mix so that it may become. In addition, the solid content concentration of the topcoat coating liquid is not particularly limited, and is preferably adjusted to, for example, about 60 to 75% by mass according to the coating apparatus and the coating amount.

  The topcoat coating solution prepared as described above is alkaline with a pH of 7 or more, so that it is easily ionically and suitably combined with the cationicity of the undercoat coating layer, and the surface strength of the topcoat coating layer can be improved. It is preferable because picking and white spots that sometimes peel off the paper surface are less likely to occur.

  In particular, as in the present invention, when an alkaline topcoat coating solution is applied onto the undercoat coating layer containing cationized starch, the pigment in the topcoat coating solution has a small positive charge and an aspect ratio. By using a clay as high as 3 to 20, it becomes more difficult for the topcoat coating solution to penetrate into the undercoat coating layer, so that not only a bulky and excellent hand-feeling coated paper is obtained, but also picking and whitening This is preferable because it is difficult for the separation to occur.

The top coat coating layer is preferably applied to both sides of the base paper at 3 to 10 g / m ² per side of the base paper, and more preferably 5 to 9 g / m ² . When the coating amount is less than 3 g / m ² per side, the coating layer is not sufficiently flattened, and the flatness and printability of the coating layer surface are poor. When the amount exceeds 10 g / m ² , the amount of pulp that can be used for the base paper is decreased, and thus a coated paper having no hand feeling is not preferable. In particular, when starch is used for the undercoat coating layer as in the present invention, the printability is hardly improved, but the coating amount of the undercoat coating layer is 0.2 to 1.0 g / m ² and the topcoat coating layer is used. When the coating amount is 3 to 10 g / m ² , a coated paper having sufficient printability and bulk can be obtained. Since the bulk of the coated paper is preferably 1.2 g / cm ³ or less after the calendar described below, it is preferable because it is bulky, and if it is 1.1 g / cm ³ or less, the coated paper becomes more bulky. preferable. In order to obtain such coated paper, the coating amount of the undercoat coating layer is 0.2 to 1.0 g / m ² , and the coating amount of the top coating layer is 3 to 10 g / m ² . It is important to do.

  For the purpose of further improving gloss, smoothness, and printability, the top coat layer can be subjected to a flattening process using a flattening facility that combines an elastic roll and a metal roll, such as a super calender or a soft calender. . Unlike conventional machine calenders, such flattening equipment treats the paper surface with a wide surface at a high temperature, thereby enabling flattening without excessively increasing the density of the base paper or the coating layer. For example, a suitable printing surface can be formed in offset printing, electrophotographic printing, and the like. Among them, a multi-nip calender, more preferably a 6-stage, 8-stage, or 10-stage multi-nip calender is preferable because the nip pressure can be easily adjusted. In particular, when a coating layer mainly composed of a pigment is provided as an overcoating layer on the undercoating layer containing cationized starch as in the present application configuration, the printability is adjusted by appropriately adjusting the linear pressure. It is preferable to use a multi-nip calender that can adjust the linear pressure as appropriate, because a decrease in hand feeling can be minimized as compared with other calender equipment.

  Moreover, as an installation place of a calendar, an on-machine type integrated with a paper machine and a coating machine is preferable. In the on-machine type, flattening can be performed immediately after coating with a high paper surface temperature, so it is easy to improve the glossiness of blank paper and the coated paper is low because the linear pressure required to obtain the desired coated paper is low. This is preferable because a coated paper that is not easily crushed and has a high hand feeling can be obtained.

  The linear pressure, temperature, and speed of the flattening treatment using various calendar facilities are not particularly limited. To improve the smoothness of the coated layer after the treatment and improve the hand feeling, for example, the linear pressure is 100. It is preferable to adjust so that it may become -300 kN / m, a metal roll temperature may be 100-200 degreeC, and a speed | rate may be 1,000-2,000 m / min.

  The white paper glossiness of the coated paper after calendering is measured according to JISP8142, and it is preferably 77% or more because it is excellent in glossiness, and if it is 79% or more, it is preferable. Therefore, it is more preferable to finish such coated paper. However, if the linear pressure is increased in order to improve the gloss, there is a problem that the bulk is lowered. Therefore, it is preferable to appropriately adjust the linear pressure.

As the top coat layer, kaolin clay having an aspect ratio of 3 to 20 is used in an amount of 3 to 10 g / m ² per one side of the base paper by using 50% by mass or more of the total pigment. Therefore, it is possible to obtain a coated paper that is more bulky, excellent in white paper gloss and hand feeling, and high in printability.

  The production system may be an on-machine coater in which the paper machine, coater part, and calendar part are integrated, or an off-machine coater in which the paper machine and coater part are separated. A system including a separate off-machine calendar may be used.

The basis weight of the coated paper thus obtained is 30 to 100 g / m ^{2 as} measured in accordance with the method described in JISP 8124 “Basis weight measurement method” from the viewpoint of ensuring printability and hand feeling. preferably, it is preferred that even at ^{50g / m 2 ~80g / m 2} . When the basis weight is less than 30 g / m ² , for example, it may be difficult to ensure paper quality strength at the same time while ensuring printability. When the basis weight exceeds 100 g / m ² , it is already sufficient. Since there is a hand feeling, the need to use the present invention is reduced.

  Next, although the coated paper of this invention is demonstrated still in detail based on the following examples, this invention is not limited only to these Examples.

Examples and Comparative Examples Undercoat coating, pre-calendar treatment, and top coating were carried out in the types and proportions shown in Table 1, to obtain a coated paper for printing. The pigments, raw materials and chemicals used are as follows.

(1) Undercoating / Cationized starch tapioca (cation) (Product number: Catosize 380 Manufacturer: Nippon National Starch Co., Ltd. Tapioca, degree of cationization: 0.020)
Corn Starch (Part No .: CHARGEMASTER R462 Manufacturer: Sansho, Corn Starch, Cationic)
Potato (Product No .: Mermaid M-350B Manufacturer: Sansho potato, Cationic)
Tapioca (anion) (Part No .: Cyprogum, manufacturer: Nippon Star Chemical Co., tapioca, anionic)
Tapioca (nonion) (part number: ZP-8, manufacturer: manufactured by Nissho Chemical Co., tapioca, nonionic)

(2) Top coating (pigment)
・ Clay: Kaolin clay (made by Imeris Co., Ltd., trade name CONTUR 1500, aspect ratio 59)
The clay shown in Table 1 was produced by pulverizing the kaolin clay using a wet pulverizer (product number: planetary mill, manufactured by Seishin Enterprise Co., Ltd.) and adjusting the aspect ratio as shown in Table 1. The aspect ratio is a value obtained by dividing the particle diameter of the pigment by the thickness of the pigment, and the particle diameter and thickness of the pigment are directly measured with an electron microscope (model number: E-MAX, manufactured by Horiba, Ltd.) for 20 arbitrary pigments. The aspect ratio was obtained by observation and dividing the average value.
・ Calcium carbonate: Heavy calcium carbonate (Product number: Hydro curve 90K, manufactured by Omiya Korea)
(Manufacturing procedure)
LBKP and NBKP are blended at a mass ratio of 80:20 as raw pulp, and each of these pulps (absolutely dry) has a solid content, cationic polyacrylamide (product number: Percoll 47, manufactured by Ciba Japan) and Anionic polyacrylamide (product number: Teriofoam M100, manufactured by Ciba Japan), internal sizing agent (product number: AK-720H, manufactured by Harima Chemicals) 0.02% by mass, cationized starch (product number: Amilofax T- (2600, manufactured by Abebe Japan) 1.0% by mass was added to obtain a pulp slurry.

  Next, in the winder part using the papermaking system including the wire part, press part, predryer part, undercoater part, afterdryer part, precalender part, top coater part, scuff dryer part, calendar part, reel part Finished product.

First, the pulp slurry is made with a wire part, then subjected to a press part and a pre-dryer part to produce a base paper with a basis weight of 40 to 43 g / m ² , and then listed in Table 1 with an undercoater part. The undercoat coating solution was undercoated on both sides by the coating method described in Table 1 so that the coating amount (g / m ² ) described in Table 1 per side was applied, and dried with an after dryer part. Then, it planarizes with a pre-calender (linear pressure 20 kN / m), and the coating liquid which consists of 8 mass parts of pigments and latex (product number: XY4, Nippon A & L Co.) listed in Table 1 in a top coater part. Then, both sides were overcoated so as to be 8 g / m ² per side, and a coated paper for printing having a basis weight of 60 g / m ² was produced. In addition, latex was made into the weight part with respect to 100 mass parts of pigments.

  Next, the calender part was subjected to a flattening process at a linear pressure of 200 kN / m and a speed of 1,500 m / min, and was applied to a winder part to obtain a coated paper for printing.

  In addition, paper was made using a gap former in the wire part, a rod metering size press coater was used in the undercoater part, and a blade coater was used in the top coater part. In the calendar part, a multi-nip calendar was used. All the above parts used an on-machine papermaking system.

  About the obtained coated paper, each physical property and characteristic were investigated with the following method. The results are shown in Table 1.

(A) Density (bulk)
Measured by a method in accordance with JIS P 8118: 1998 “Paper and paperboard—Test method for thickness and density”.

(B) White paper gloss Using a color analyzer (model number: color i5, manufactured by Macbeth Gretag Co., Ltd.), the gloss was measured by a method based on JIS P 8142: 2005 “Paper and paperboard—Measurement method of 75 degree specular gloss”.

(C) Hand feeling 20 samples of A4 size (210 mm x 297 mm) are stacked, one side of the long side is stapled at 3 locations (top, center, bottom) and placed horizontally, turning 10 sheets in total, The hand feeling of paper was evaluated based on the following evaluation criteria.
A: The paper after turning does not sag and is excellent in hand feeling.
○: The paper after turning is slightly sagged and slightly inferior to the hand feeling.
Δ: The paper after turning is slightly sagging and slightly inferior to the hand feeling.
X: The paper after turning is sagging, and the hand feeling is inferior.

(D) Printability Using an offset printing machine (model number: Lithopia L-BT3-1100, manufactured by Mitsubishi Heavy Industries, Ltd.), color 4 (color: product number: ADVAN, manufactured by Dainippon Ink & Chemicals, Inc.) 5000 copies of color printing were performed. About this printing surface, the printing nonuniformity of the printed matter was observed visually and with a magnifying glass (10 times), and the degree thereof was evaluated based on the following evaluation criteria.
A: There is no printing unevenness, excellent printability, and practical use.
○: Printing unevenness occurs slightly and printability is slightly inferior, but it can be used in practice.
Δ: Some printing unevenness occurs and printability is slightly inferior, but it can be used in practice.
X: Printing unevenness occurs, printability is poor, and actual use is impossible.

  From Table 1, it was bulky in Examples 1-33 which provided the undercoat coating layer which does not contain a pigment but contains a cationized starch, and provided an overcoat layer composed of a pigment and an adhesive on the layer. It can be seen that a coated paper having excellent gloss and hand feeling and high printability was obtained.

  The coated paper of the present invention can be suitably used as any paper such as printing paper, packaging paper, information recording paper, and newsprint.

Claims (3)

  A coated paper provided with at least two coating layers on a base paper, wherein a coating layer containing a cationized starch not containing a pigment is provided as an undercoat coating layer in contact with the base paper, on the undercoat coating layer A coated paper comprising a coating layer comprising a pigment and an adhesive as a top coating layer.   The coated paper according to claim 1, wherein the cationized starch is a cationized tapioca starch, and the cationized tapioca starch has a degree of cationization of 0.010 to 0.040.   The coating material according to claim 1 or 2, wherein kaolin clay having an aspect ratio of 3 to 20 is contained in an amount of 30 parts by mass or more with respect to 100 parts by mass of the total pigment as the pigment of the top coating layer. paper.