JP4850795B2 - Coated paper - Google Patents

Description

  The present invention relates to coated paper. In particular, the present invention relates to a light-weight, fine-coated paper.

In recent years, this type of coated paper has been promoted to reduce the base weight of the base paper and to finely coat the coating layer from the viewpoints of resource saving and transportation cost reduction (for example, see Patent Documents 1 to 3). .)
However, as the weight is reduced, the stiffness (clerk) decreases, problems such as paper passing problems during printing, paper handling and paper alignment during processing are difficult, and magazines and the like are difficult to turn pages. Arise. Further, the reduction in weight and fine coating also cause problems in printability such as ink breakthrough, lower print gloss, and uneven printing surface.
JP 2003-82599 A Japanese Patent Laid-Open No. 62-177299 JP 2002-105888 A

  The main problem to be solved by the present invention is to provide a coated paper which is excellent in printability, resource saving and transportation cost reduction.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
On the base paper surface, an undercoating liquid mainly composed of a water-soluble polymer is applied to provide an undercoating layer, and the surface of the undercoating layer is smoothed by a pre-calender and then an ink receiving layer Provided,
The ink receiving layer is mainly composed of an adhesive and a pigment,
As the pigment, at least deinked floss as a main raw material, calcium, silicon, and aluminum obtained through a dehydration step, a drying step, a firing step, and a pulverization step are converted into oxides in an amount of 30 to 82: 9 to 35: 9. Containing regenerated particles containing at a mass proportion of ~ 35,
Coated paper characterized by that.

[Invention of Claim 2]
The regenerated particle-coated paper according to claim 1, wherein the regenerated particles have a total content of 90% by mass or more of the calcium, the silicon, and the aluminum.

[Invention of Claim 3]
The under coating layer, according to claim 1 or 2, playback particles coated paper, wherein the 0.5 to 1.2 g / m ^2.

  According to the present invention, the coated paper has excellent printability, resource saving, and transportation cost reduction.

Next, an embodiment of the present invention will be described.
[Coated paper]
In the coated paper of this embodiment, a flattened undercoating layer is provided on the surface of the base paper, and an ink receiving layer is provided thereon. The under coating layer is formed by applying an under coating liquid mainly composed of a water-soluble polymer such as starch. Undercoat layer is provided by applying undercoat liquid mainly composed of water-soluble polymer such as starch, and ink receiving layer is provided on this, so it is absorbed by the base paper. The amount of the coating liquid that does not affect the printability is reduced. Therefore, improvement in printability and resource saving can be expected. In addition, since the undercoating layer is flattened with a calendar or the like, the weight of the ink receiving layer can be reduced, and resource saving and transportation cost reduction can be expected.

  Here, the under coating liquid is preferably applied by a roll coater. The coating is performed by a roll coater, and the (under) coating layer by this coating is flattened, whereby fine coating can be promoted while ensuring the flatness of the coated paper surface.

  As for the base paper of this form, the kind of raw material pulp is not specifically limited. Examples of the raw material pulp include wood pulp, non-wood pulp, synthetic pulp, waste paper pulp, and the like, and more specifically, groundwood pulp (GP), stone grand pulp (SGP), refiner ground pulp (RGP), processing pulp, and the like. Mechanical pulp (MP), chemical mechanical pulp (CGP), semi-chemical pulp such as compressed ground pulp (PGW), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), bleach chemithermomechanical pulp (BCTMP) (SCP), hardwood bleached kraft pulp (LBKP), kraft pulp (KP) such as softwood bleached kraft pulp (NBKP), chemical pulp such as soda pulp (AP), sulfite pulp (SP), dissolved pulp (DP) (CP), nylon, rayon, polyester, polyvinyl alcohol Raw paper pulp such as synthetic pulp, deinked pulp (DIP), waist pulp (WP), waste pulp (TP), cotton, flax, hemp, jute, manila hemp, ramie, etc. One or several kinds can be appropriately selected and used from slag pulp, straw pulp, esparto pulp, bagasse pulp, bamboo pulp, kenaf pulp and other auxiliary pulps such as bast pulp.

However, in the base paper of this embodiment, the raw material pulp type is preferably such that the mass ratio of NBKP: LBKP: mechanical pulp is 15-50: 40-50: 10-35, 25-45: 42- 48:12 to 33 is more preferable. If the weight ratio of NBKP is less than 20%, the paper weight strength may be insufficient when the basis weight at which the present invention can be suitably used is 51.2 to 60.2 g / m ² . If the mass ratio exceeds 45%, the base paper tends to have uneven thickness because it is difficult to obtain a uniform base paper formation due to the long fibers peculiar to the N material. If the mass ratio of LBKP is less than 40%, the denseness of the base paper surface is inferior because of the wide and short fibers unique to the L material, and when a coating layer is provided, the penetration unevenness of the coating liquid and the film moldability are reduced. On the other hand, if the mass ratio of LBKP exceeds 50%, the density of the base paper tends to be high, and cushioning properties and bulkiness in the thickness direction (Z-axis direction) are reduced. Mechanical pulp is obtained by grinding and pulverizing wood, is short and rigid, and has fine beard-like fiber branches and leaves called fibrils on the fiber surface. Therefore, if the mass ratio of mechanical pulp is less than 10%, the bulky effect is not exhibited, and the rigidity cannot be improved. On the other hand, when the mass ratio of mechanical pulp exceeds 33%, the influence of rigid mechanical pulp is noticeable, and when the coating layer is provided, the surface of the coating layer is uneven, and a fine bearded shape is formed. Since the fiber branches and leaves absorb the coating solution quickly and increase, the flatness of the coated surface may be further impaired. In the present invention, waste paper pulp can also be used as the raw material pulp. Waste paper pulp is pulp that has been once paper-made and regenerated as paper raw material. Therefore, the softwood kraft pulp, the hardwood kraft pulp, and the mechanical pulp, which are the inherent raw material pulp types, are both flat and flexible fibers due to heat during regeneration and physical regeneration means, and the strength of the pulp itself is Although it is low, it contributes to improving the flatness and glossiness of the paper surface.

The base paper of this embodiment preferably has a Canadian standard freeness of 160 to 400 cc (CSF) based on JIS P 8121: 1995 when disaggregated based on JIS P 8220: 1998. More preferably, it is 360 cc (CSF). When the Canadian standard freeness falls below 160 cc (CSF), the dewatering power is reduced in the wet end process (wet paper forming process) in papermaking with a basis weight of 40 to 64 g / m ^2. Are difficult to orientate in the Z-axis direction, resulting in a problem that the strength of the paper is lowered and a problem that the speed cannot be increased further in high-speed papermaking exceeding 1300 m / min, resulting in a decrease in productivity. Further, if the Canadian standard freeness is less than 160 cc (CSF), the density of the base paper tends to be high, and there is a possibility that the coated paper having a light weight and excellent printability, which is a problem to be solved by the present invention, may not be obtained. . On the other hand, if the Canadian standard freeness exceeds 400cc (CSF), the formation of the base paper is likely to be disturbed, and not only a uniform formation is obtained, but also the gaps between the pulp fibers are uneven, When provided, there is a possibility that uneven penetration of the coating liquid occurs and printability is deteriorated.

  As for the base paper of this form, when it disaggregates based on JIS P 8220: 1998, the mean length of the meander fiber measured with the mean length fiber length measuring device (FS-100) is 0.85 to 1.20 mm. It is preferable that it is 0.90 to 1.10 mm. If the average fiber length is less than 0.85 mm, the density of the base paper may increase, leading to a decrease in stiffness, and the proportion of fine fibers increases, so that paper dust is likely to occur during cutting. Because. On the other hand, if the average fiber length of Kayani exceeds 1.20 mm, the ratio of long fibers is large, so it is difficult to form the base paper, and when the coating layer is provided, the glossiness decreases and uneven coating occurs. There is a fear.

  The coated paper of this embodiment has a “longitudinal stiffness (Clark) based on JIS P 8143: 1996” / “(product) basis weight based on JIS P 8124: 1998” of 0.30 to 0.60. It is preferable that it is 0.35 to 0.55. When this value is less than 0.30, it becomes a coated paper with no stiffness, processing and printing workability deteriorates, and it becomes a cheap paper with no hand feeling. On the other hand, when this value exceeds 0.60, it becomes difficult to handle in applications such as a leaflet inserted into a newspaper, and the newspaper becomes bulky.

  The coated paper of this embodiment preferably has a vertical stiffness (Clark) of 14 or more and a horizontal stiffness (Clark) of 8 or more based on JIS P 8143: 1996. More preferably, the stiffness (clerk) is 15 or more, and the lateral stiffness (clerk) is 9 or more. This is because if the stiffness in the vertical direction (clerk) is less than 14, the printed product easily falls when it is held in the hand, and it is difficult to read and handle the print information. Moreover, when the horizontal stiffness (Clark) is less than 8, when the book is processed into a book or booklet, the page is difficult to turn and the book formability is poor.

The coated paper of this embodiment preferably has a (product) basis weight based on JIS P 8124: 1998 of 40 to 64 g / m ^2, and 51.2 to 60.2 g / m ² . Is more preferable. This is because when the product basis weight is less than 40 g / m ² , it is difficult to obtain the paper strength necessary for printing work and processing, and the coated paper has low stiffness. On the other hand, if the product basis weight exceeds 64 g / m ² , it is contrary to the recent resource saving and weight reduction, and the manufacturing cost and the distribution / conveyance cost increase.

  The coated paper of this embodiment preferably has a blank paper glossiness of 30% or more based on JIS P 8142: 2005, more preferably 40 to 56.5%. If the glossiness of blank paper is less than 30%, clear print information and high contrast print information cannot be expressed, resulting in lack of detail. On the other hand, the glossiness of the blank paper may exceed 56.5%, but by setting it to 56.5% or less, the so-called glare is not visible in the recent trend of aging and eyestrain The coated paper is gentle on the eyes.

  The ink receiving layer of this embodiment is mainly composed of an adhesive and a pigment, and as this pigment, deinking floss is the main raw material, and is obtained through the dehydration process, the drying process, the firing process, and the pulverization process, Recycled particles containing aluminum at a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxide, and a total content ratio of the calcium, the silicon and the aluminum of 90% by mass or more, It is preferably used at least, and contains calcium, silicon, and aluminum in a mass ratio of 40 to 82: 9 to 30: 9 to 30 in terms of oxides, and the total of the calcium, silicon, and aluminum More preferably, regenerated particles having a content ratio of 90% by mass or more are used, and calcium, silicon and aluminum are used. It is contained at a mass ratio of 60 to 82: 9 to 20: 9 to 20 in terms of a compound, and more preferably, regenerated particles having a total content ratio of 90% by mass or more of the calcium, the silicon and the aluminum are used at least. It is particularly preferred that

  As a method to adjust the oxide equivalent ratio of regenerated particles calcium, silicon and aluminum, the main method is to adjust the raw material composition in the deinking floss, but the source is clear in the drying / classification process and firing process It can also be adjusted by a method of adding a coating floss or adjustment process floss in the process by spraying or a method of containing incinerator scrubber lime.

  More specifically, for example, neutral papermaking wastewater sludge and coated paper manufacturing process wastewater sludge are used to adjust calcium in regenerated particles, and silicon is added in large amounts as an opacity improver. For the adjustment of aluminum, use the papermaking wastewater sludge used in the acid papermaking system and other sulfuric acid bands, and the wastewater sludge in the high quality papermaking process that uses a lot of clay. be able to.

  The regenerated particles of this embodiment have an oil absorption of 30 to 100 ml / 100 g, for example.

The regenerated particles of this embodiment are preferably treated so that the particles having a size of 40 μm or less are 90% or more before the pulverization step after the above-described dehydration step, drying step, firing step, and the like. This makes it possible to perform a one-stage pulverization process by a wet process without performing a multi-stage pulverization process such as pulverization of large particles by dry pulverization and micronization by wet pulverization, which are generally performed conventionally. Thereby, the peak height of the average particle diameter in the differential curve of the particle size distribution by the Coulter counter method can be set to 30% or more. Furthermore, calcium, silicon and aluminum in the deinking floss can be converted to 30 to 30 in terms of oxides. By adjusting the mass ratio to 82: 9 to 35: 9 to 35, the pore volume of the regenerated particles is 0.15 to 0.60 cc / g, the pore surface area is 10 to 25 m ² / g, and the pore radius is It can be 300-1000 Angstroms.

  In this embodiment, the above regenerated particles can be used alone, but such regenerated particles and pigments are usually used, for example, heavy calcium carbonate, light calcium carbonate, talc, clay, kaolin, titanium dioxide. In addition, inorganic particles such as synthetic silica and aluminum hydroxide, synthetic polymer fine particles such as polystyrene resin and urea formaldehyde resin, and the like can be used in combination.

〔Production method〕
Next, the manufacturing method of the coated paper of this form is demonstrated.
In this embodiment, the paper is made at a high operating speed of 1300 m / min or more (for example, the average operating speed is 1600 m / min, the design operating speed is 1800 m / min), and coating such as undercoating and surface finishing are performed. For example, the basis weight of the base paper is 31 to 50 g / m ² , preferably 41 to 48 g / m ² , and the basis weight of the product (coated paper) is 40 to 64 g / m ² , preferably 51.2 to 60.2 g / It is intended to produce m ² coated paper.

Hereinafter, the present embodiment will be described based on the equipment configuration flow diagrams of FIGS.
[Wire part (head box)]
In this embodiment, a paper layer (jet) J (see FIG. 6) is ejected from the head box 3 between two looped wires (first wire 1 and second wire 2) to form a paper layer. A paper machine for making paper with the gap former 10 is installed. In the wire part, the paper material J is discharged between the wires 1 and 2 between the suction (forming) roll 4A and the opposite roll 4B to form a paper layer, and the paper layer includes the suction roll 4A, the blade 5, While passing through the suction couch roll 6, the suction box 7, etc., for example, the material is dehydrated to a raw material concentration of about 20%.

  Here, as the dewatering mechanism, a combination form of the roll dewatering means and the blade dewatering means is shown in the illustrated example, but preferably both (combined use), but only one of them can be used. By dewatering at the wire part, the paper J discharged from the head box 3 is gently performed by the suction roll 4A so that the fine fibers are kept in the wet paper, and further dewatering is performed by the dewatering means by the blade 5. Decrease in internal bond can be prevented.

  The head box 3 is installed upward in a state of being inclined vertically or downstream, and as shown in an enlarged view in FIG. 6, the discharge angle θ between the paper discharge direction line and the horizontal line is 50 to 90 ° (degrees). It is desirable. Under the high-speed papermaking intended by this embodiment, an upward headbox that is less affected by fiber weight is desirable in terms of formation, Z-axis strength, front / back difference, fiber orientation angle, and the like. In the gap former 10, if the head box 3 is horizontal or the like, it is difficult to obtain characteristics required under high-speed papermaking.

[Press part]
The paper layer in the wire part is transferred to the press part and further dewatered.
In the press part of this embodiment, each of the first press 21 and the second press 22 has a shoe press 21a or 22a, and a form in which a paper layer is nipped straight in order to eliminate open draw and prevent sheet breakage (straight) Through-type press). In addition, the second press 22 employs a belt on the bottom side of the double felt first press 21 to improve dewatering by preventing rewetting. When the paper layer basis weight is as high as 60 g / m ² or more and the dewatering amount is increased, double felt is desirable.

[Pre-dryer part]
The wet paper (wet paper layer) having a moisture content of about 50% that has passed through the press part is transferred to a single-deck type pre-dryer part and dried. The illustrated pre-dryer part is a single deck dryer of a no-open draw type, and has an appropriate number of roll configurations in which the upper side is a heating roll 31 and the lower side is a vacuum roll 32.

  Single-deck dryers are less likely to break during high-speed operation (papermaking) of 1300 m / min or more, which is intended by the present invention / form, and can be dried efficiently without reducing bulk, in terms of quality and operation. Are better. In this respect, a method of drying with a double-deck type dryer is also conceivable, but there are problems in terms of operability such as canvas marks in high-speed papermaking, paper breaks in high-speed drying, wrinkles, and paper splicing.

  In the initial stage of the pre-dryer part, it is desirable to make the grouping fine for adjusting the draw, and to install the suction box 33 for improving the paper passing property and the sheet running property.

[Undercoating part]
The web (dried paper layer) dried in the pre-dryer part is mainly composed of a water-soluble polymer such as a sizing agent such as starch in the undercoater 40 by film transfer (method) with the after-dryer part. Undercoat (under) coating solution is applied to both sides.

  As the under coater 40, in addition to the rod metering size press coater shown in FIG. 3, a gate roll coater 40A shown separately in FIG. 3 can be used. In the present invention, the roll coater is preferable as described above.

  As the undercoat coating solution, in addition to the starch described above, starch derivatives such as oxidized starch, esterified starch, enzyme-modified starch, and etherified starch, and natural adhesives such as soybean protein, yeast protein, and cellulose derivatives should be used. Can do.

  If necessary, a pigment may be added. Examples of the pigment include ordinary pigments for coated paper such as kaolin, clay, barium sulfate, light calcium carbonate, heavy calcium carbonate, aluminum hydroxide, satin white, titanium dioxide, calcium sulfite, zinc sulfate, and plastic pigment. , And can be blended according to the respective pigment properties.

  Furthermore, examples of the adhesive include conjugated diene copolymer latex such as styrene / butadiene copolymer and methyl methacrylate / butadiene copolymer, and acrylic and / or methacrylic ester polymer or copolymer. Adhesives for ordinary coated paper, such as synthetic resin adhesives such as alkali-insensitive or alkali-sensitive synthetic resin emulsions such as polymer-based polymer latex and vinyl acetate copolymer latex such as ethylene / vinyl acetate copolymer Can be used. If necessary, various auxiliary agents such as a dispersant, a flow modifier, an antifoaming agent, a dye, a lubricant, a water-resistant agent, and a water retention agent can be blended.

The coating amount of the undercoat (under) coating solution is preferably 0.5 to 1.2 g / m ² .

  As the film transfer system coating means described above, for example, a gate roll coater, a two-roll size press, an optimizer, a blade metering size press, a rod metering size press, or the like can be used. However, when a rod metering size press is used, it is desirable to use a rod with a smooth surface in order to avoid streak in operation. By setting the diameter of this rod to 15 to 50 mm, more preferable operability and quality can be obtained. When the rod is smaller than 15 mm in diameter, the film forming performance tends to be low and the surface shape tends to be inferior. On the other hand, since the effect does not change with a rod having a diameter larger than 50 mm, there is no need to make it particularly large. As the rod, a grooved rod, a wire wire winding rod, or the like can also be used.

  After applying the undercoat (under) coating solution, it is desirable to install an air turn bar 41 and an auxiliary drying device 42 using infrared rays in advance so that surface contamination does not occur in the after dryer part.

[After-dryer part]
In the illustrated single-deck type after-dryer part, the undercoat coating solution such as a sizing agent or a pigment coating solution is dried.

[Pre-calendar]
Thereafter, an aqueous coating liquid mainly composed of an adhesive and a pigment (such as clay) is applied by a coater part to form an ink receiving layer. In this case, high smoothness and glossy high quality coated paper is required at a basis weight of 40 to 64 g / m ² based on the present invention under conditions of a papermaking speed of 1300 m / min or more. Therefore, it is adopted from the viewpoint of the quality of the coated paper that can be obtained as roll coating capable of contour coating the aqueous coating liquid. However, in order to ensure higher smoothness before roll coating of the aqueous coating liquid, the surface of the undercoat paper layer coated with the undercoat (under) coating liquid is flattened (smoothed) by the pre-calender 50. It is desirable to process. In the pre-calender 50 of the embodiment, the upper side is a metal roll 51 and the lower side is an elastic roll 52.

  By the treatment with the pre-calender 50, the surface of the base paper (undercoating paper layer) can be flattened, and the tension of the paper is increased by not requiring an excessive flattening treatment in the subsequent thermal soft calender. The flatness of the surface of the base paper can be improved without any problem, and a bulky coated paper can be obtained. In addition, the occurrence of coating unevenness of the coating liquid can be suppressed by the flattening treatment of the base paper surface.

  The surface roughness (JIS B 0601) of the metal roll 51 in the pre-calender 50 is preferably 0.02 to 0.2 μm, and the Shore D hardness of the elastic roll 52 is desirably 90 or more.

  Further, the nip pressure in the pre-calender 50 is 5 to 50 kN / m, preferably 10 to 40 kN / m. When the nip pressure is less than 5 kN / m, the smoothness of the base paper is poor. On the other hand, when the nip pressure exceeds 50 kN / m, the paper tension becomes excessive.

  As the metal roll 51 of the pre-calender 50, if necessary, a heating medium such as oil is circulated and heated in the same manner as the thermal soft calender described later, and an internal heating device using an electromagnetic induction action capable of dividing temperature control in the roll width direction. , Those equipped with an external heating device with electromagnetic induction capable of controlling the division temperature in the roll width direction, those equipped with cooling equipment capable of controlling the cooling temperature in the roll width direction, and the like can be employed.

[Coater part (coating process)]
The coater part in this embodiment has a coating process that bears coating on both sides of the coated paper.
That is, a coating machine 61A for the surface of the base paper, gas type air dryers 62 and 62, and a canvas dryer 63 are installed in this order. Desirably, an infrared drying device 68 capable of controlling the temperature in the width direction is provided in the subsequent stage of the coating machine 61A to prevent unevenness in the width direction. In addition, it is desirable to provide an infrared drying device that can control the temperature in the width direction mainly for adjusting the moisture content, after the coating machine 61A. If necessary, an infrared drying device can be provided downstream of the gas air dryers 62 and 62.

In the coating machine 61A, a roll coating machine is used, and a gate roll coater and a rod metering size press are particularly desirable. The coating amount in the coating process is preferably 8.0 to 12.0 g / m ^{2 on} both sides.

[Calendar part]
At the end of this facility, an on-machine calendar 70 composed of a thermal soft calendar is installed, and calendar processing is performed. The illustrated calendar 70 is a 7-nip one-stack type, and has a Janus type inclined arrangement in which the influence of the roll weight is reduced. Of course, an optical load type vertical arrangement may be used.

  The calendar 70 determines the final smoothness and gloss. Therefore, various considerations are necessary from this viewpoint and from the viewpoint of high-speed operation.

  The calender 70 preferably has at least two nips, and is more preferably flattened with a thermal soft calender composed of a combination of metal rolls M and elastic rolls D formed in a plurality of stages. In particular, a multi-nip calender, more preferably a 6-, 8-, or 10-stage multi-nip calender is optimal. FIG. 4 shows an example of a 10-stage multi-nip calendar. Furthermore, a multi-nip calender that can adjust the nip pressure independently at all stages is optimal.

  On the other hand, the heat soft calender may be heated by circulating a heat medium such as oil, but this limits the surface temperature of about 180 ° C. In order to operate at high speed, as shown in FIGS. 7 to 9, the metal roll M is equipped with an internal heating device by electromagnetic induction that can control the division temperature in the width direction. It is desirable to treat at a temperature of 230 ° C. or higher, particularly 230 to 500 ° C. In the illustrated example, an induction coil 71 is wound around an iron core 72 in a shell 74 to heat a heat medium passing through a jacket chamber 73.

  The surface temperature of the metal roll M is set to 230 ° C. to 500 ° C., particularly more than 300 ° C. and 380 ° C. or less, so that the base paper (coated paper) is not crushed over the entire layer at the lowest possible nip pressure. By doing so, it is possible to perform an operation capable of preventing a decrease in bulk and suppressing a decrease in opacity. In short, it is a form in which an extremely hot iron is applied in a short time.

  As described above, in order to control the surface temperature of the metal roll M, in addition to the method of circulating hot water or oil inside the metal roll M, the induction coil 71 is provided around the iron core 72 provided on the inner side as a non-rotating part. By providing an alternating current to the induction coil 71, a magnetic flux is generated in the induction coil 71 to induce an induction current inside an outer shell (outer cylinder) 74 as a rotating portion, and the outer shell is caused by the resistance heat. The “outer cylinder” 74 that self-heats (inductive heat generation) by the “internal heating device using electromagnetic induction” is particularly excellent for high-temperature processing. Further, according to the internal heating device by this electromagnetic induction action, the induction coil 71 is divided in the roll width direction (longitudinal direction of the roll itself) (for example, divided into 3 to 6), and the temperature by the temperature sensor 75 provided on the shell 74 is determined. By controlling the amount of alternating current flowing through the corresponding induction coil 71 based on the signal, temperature control of the surface in the width direction of the roll can be performed with high accuracy.

  In this case, in particular, a number of, for example, about 10 to 90 jacket passages (chambers) 73 extending in the longitudinal direction are provided in the inside of the shell 74 at intervals in the circumferential direction. The structure to be sealed is excellent in that the heat generated by the self-heating of the shell 74 is absorbed and the heat can be made uniform over the entire surface of the metal roll M.

  When the surface of the base paper (coated paper) is treated at a high temperature, not only the surface layer of the base paper (coated paper) but also the temperature of the inner layer increases, and as a result, the base paper (coated paper) is only the surface layer. In addition, since it becomes easy to be crushed over all layers, the bulk is reduced. However, when paper is passed for a short time at a much higher temperature, heat transfer to the inner layer portion can be prevented as much as possible, thereby preventing a decrease in bulk.

  On the other hand, as the surface temperature of the metal roll M rises, stress in the thickness direction is generated in the shell 74 of the metal roll M, and the roll profile tends to collapse, thereby reducing the controllability of the paper thickness profile. Moreover, when it depends on the internal heating apparatus by electromagnetic induction action, it cannot be said that the temperature responsiveness per time of the surface temperature of the metal roll M is good. Furthermore, the temperature responsiveness in the width direction is poor due to this, which causes a decrease in yield due to poor temperature controllability. Therefore, it is desirable that near the metal roll M, at least one of an external heating device using an electromagnetic induction function capable of controlling the division temperature in the roll width direction and a cooling facility capable of controlling the cooling temperature in the roll width direction are provided.

  This example will be described with reference to FIG. 8. The metal roll M includes a shell 74, an induction coil 71, an iron core 72, a temperature sensor 75, an AC power source 76, and a jacket path 73. For this metal roll M, an external heating device 77 by an external electromagnetic induction action that can be divided and controlled in the width direction is provided in the vicinity of the metal roll M to form a high temperature nip region of the base paper in each stage.

  The external heating device 77 applies the principle of electromagnetic induction heating. As shown in the figure, an AC current (for example, a high frequency of 3 to 20 kHz) from an AC power source (inverter) 77B is passed through the work coil 77A to generate a magnetic field. Thus, an eddy current is generated on the surface portion of the shell 74 to cause self-heating. The distance between the work coil 77A and the surface of the shell 74 is desirably 2 to 20 mm, particularly about 2 to 5 mm. Further, it is desirable that the unit work coil 77A be disposed obliquely so as to intersect the axis of the metal roll M in order to make the heating profile uniform. The zone control pitch in the roll width direction is about 75 to 150 mm, and the rated power per zone can be 4 to 20 kW.

  As an example of the cooling equipment 78 capable of controlling the cooling temperature in the roll width direction, as shown in FIG. 9, the air from the fan 78a is sent to the header 78b, and the inside of the temperature control chamber 78d is passed through the adjustment plate 78c in which the communication holes are formed. The coil 78e provided in the temperature adjusting chamber 78d is cooled by the temperature adjusting means 78f, thereby controlling the temperature of the air passing through the dispersion plate 78g having small holes.

  The nip pressure in the calendar 70 is preferably 200 kN / m to 450 kN / m, particularly 300 kN / m to 450 kN / m. The base paper (coated paper) that has been smoothed (planarized) by the calendar 70 is finally wound by a reel 80, and a winder (not shown) that finishes winding for subdivision. Installed in the last part of the machine.

  In place of the multi-nip calender 70 shown in FIG. 4, as shown in FIG.

Next, examples of the present invention will be described.
The coated gloss produced under the conditions shown in Tables 1 to 3 was evaluated for printing gloss (primary) and ink fillability. The results are shown in Tables 1-3. Measurement conditions and evaluation methods are as follows.

[Canadian standard freeness]
It disaggregated based on JIS P 8220: 1998, and measured based on JIS P 8121: 1995.

[Kayani average fiber length]
It disaggregated based on JIS P 8220: 1998, and measured with the Kayani average fiber length measuring device (FS-100).

[Base paper basis weight]
Measured based on JIS P 8124: 1998.

[Mass ratio of pigment (clay, calcium carbonate and regenerated particles)]
After ashing based on JIS P 8251: 2003, elemental analysis is performed with a microanalyzer (manufactured by Hitachi / Horiba) to compare the individual element existence sites of calcium, silicon, and aluminum, and aggregates containing only Ca element In the case of calcium carbonate, Si and Al elements as components constituting a mass ratio of about 42 to 46:37 to 40 as clay, and a composition composed of Ca, Al and Si elements as regenerated particles, respectively. The approximate mass ratio of was calculated.

[Product basis weight]
Measured based on JIS P 8124: 1998.

[Paper thickness]
Measured based on JIS P 8118: 1998.

[Intensity (bulk density)]
Measured based on JIS P 8118: 1998.

[Blank gloss]
Measured based on JIS P 8142: 2005.

[Beck smoothness]
Measured based on JIS P 8119: 1998.

[Stiffness (Clark)]
Measured based on JIS P 8143: 1996.

[Print gloss (primary)]
Solid printing was performed with an RI printer using an offset printing ink, and measurement was performed based on JIS P 8142: 2005.

[Ink fillability]
Using an offset test printer, four-color solid printing was performed at a printing speed of 1000 rph, and the printing surface of each color was visually evaluated in four stages. A: Excellent, B: Excellent, B: Somewhat problematic, B: Problem.

  The present invention can be applied as a coated paper suitable for weight reduction and fine coating.

It is an outline explanatory view showing the 1st zone of the example of equipment composition. It is an outline explanatory view showing the 2nd zone of an example of equipment composition. It is an outline explanatory view showing the 3rd zone of an example of equipment composition. It is a schematic explanatory drawing which shows the 4th zone of an installation structural example. It is a schematic explanatory drawing which shows the modification in the 4th zone of an equipment structural example. It is outline | summary explanatory drawing which shows the ejection of the paper stock of a head box. It is a schematic explanatory drawing which shows a heating metal roll. It is a schematic explanatory drawing which shows the example of the external heating apparatus by an electromagnetic induction effect | action. It is an outline explanatory view showing an example of cooling equipment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st wire, 2 ... 2nd wire, 3 ... Head box, 5 ... Blade, 10 ... Gap former, 21 ... 1st press, 22 ... 2nd press, 40 ... Undercoater, 50 ... Precalender, 51 ... Metal roll, 52 ... Elastic roll, 61A ... Coating machine, 70 ... On-machine calendar, M ... Metal roll, D ... Elastic roll, 80 ... Reel.

Claims (3)

On the base paper surface, an undercoating liquid mainly composed of a water-soluble polymer is applied to provide an undercoating layer, and the surface of the undercoating layer is smoothed by a pre-calender and then an ink receiving layer Provided,
The ink receiving layer is mainly composed of an adhesive and a pigment,
As the pigment, at least deinked floss as a main raw material, calcium, silicon, and aluminum obtained through a dehydration step, a drying step, a firing step, and a pulverization step are converted into oxides in an amount of 30 to 82: 9 to 35: 9. Containing regenerated particles containing at a mass proportion of ~ 35,
Coated paper characterized by that.   The regenerated particle-coated paper according to claim 1, wherein the regenerated particles have a total content of 90% by mass or more of the calcium, the silicon, and the aluminum. The under coating layer, according to claim 1 or 2, playback particles coated paper, wherein the 0.5 to 1.2 g / m ^2.

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