JP2011190558A - Coated paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide coated paper for printing, suppressing generation of wrinkles even by printing with a high-speed rotary offset printing machine, especially at a printing speed of 1,000 rpm or higher, and giving printed matter of good appearance and favorable finish owing to high white paper gloss and printing gloss and high surface strength. <P>SOLUTION: Pigment in a coating layer of the coated paper includes pigment particles having a particle diameter of not less than 2 μm in an amount accounting for 5% or less of total pigment particles, and the coating layer contains 4-7 pts.mass, based on 100 pts.mass of the pigment, of an adhesive comprising a styrene-butadiene latex having a butadiene component content of not less than 50 mass%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to coated paper. More specifically, the present invention relates to a coated paper for printing that prevents the occurrence of wrinkles that occur in offset printing and that has excellent print gloss and good appearance.

In recent years, with the increase in the speed of printing presses, the drying temperature on offset rotary printing presses has increased, and wrinkles caused by the difference in shrinkage between the image area and the non-image area, called hijiwa, in the drying process after printing. Is a problem. When coated paper dries, it shrinks because the water in the coated paper evaporates as water vapor. At this time, the printing ink is on the image area, and the water vapor evaporates compared to the non-image area. Is suppressed, and wrinkles are generated due to the difference in contraction. Various proposals have been made to suppress the occurrence of elbows.

As a technique for suppressing the generation of wrinkles, a technique of containing an α-olefin-α-diisobutylene-maleic anhydride copolymer as a sizing agent and adjusting it to a specific size (see Patent Document 1), or the most surface side A technique for processing coated paper containing a plastic pigment in the coating layer with a shoe calender (see Patent Document 2), and a technique for spraying a plastic pigment and a surface sizing agent on the coating layer (Patent Document 3) And a technique for providing a coating layer containing hollow resin particles having an average particle diameter of 0.5 to 3.0 μm as a pigment component in the lowermost layer of the coating layer by a film transfer method (see Patent Document 4) Has been proposed.

In addition, deinking floss is used as a main raw material, and the main raw material is obtained through dehydration, drying, combustion, and pulverization processes, and the combustion process is performed in a first combustion furnace and a deinking floss burned in the first combustion furnace. Regenerated particles obtained by having a combustion process of at least two stages having a later second combustion furnace, wherein the first combustion furnace performs a combustion treatment at 300 ° C. or higher and lower than 500 ° C. There is also a technique in which a coating layer contains a pigment as a pigment (Patent Document 5).

Although the above technique can reduce the generation of wrinkles to some extent, in recent high-speed rotary offset printing, the printing speed (the rotation speed of the blanket cylinder) has been increased from about 600 rpm to 1000 rpm or more, and drying after printing is performed accordingly. The temperature is also high, and printing conditions are likely to cause wrinkles. At such a printing speed, the drying temperature is 110 ° C. or higher, more preferably 115 ° C. or higher as the paper surface temperature, and particularly wrinkles are likely to occur. Even using the above technique, wrinkles cannot be sufficiently prevented. However, there was a problem that a printed matter having a high level and good appearance could not be obtained as required.
JP 2004-211131 A JP 2006-138025 A JP 2007-154330 A Japanese Patent Laid-Open No. 2007-212357 Japanese Patent Application No. 2008-227128

The object of the present invention is to suppress generation of wrinkles even when printing is performed using a high-speed rotary offset printing machine, particularly a high-speed rotary offset printing machine having a printing speed of 1000 rpm or more. Is to provide a good coated paper for printing.

The present invention is a coated paper having a base paper and a pigment coated layer mainly composed of a pigment and an adhesive on the base paper, wherein the pigment particles having a particle diameter of 2 μm or more are all pigment particles. %, And the adhesive contains at least a styrene-butadiene latex having a butadiene component of 50% by mass or more, and the ratio of the adhesive to 100 parts by mass of the pigment is 4 to 7 parts by mass. , Coated paper.

Furthermore, it is preferable that the base paper contains recycled particles obtained from papermaking sludge as a main raw material and subjected to a dehydration step, a drying step, a heat treatment step of at least three steps, and a pulverization step.

Furthermore, a clear coating layer mainly comprising starch is provided between the base paper and the pigment coating layer, and the starch is an oxidized starch obtained by oxidation with potassium hydrogen persulfate. Is preferred.

The coated paper according to the present invention suppresses generation of wrinkles even when printing is performed using a high-speed rotary offset printing machine, particularly a high-speed rotary offset printing machine with a printing speed of 1000 rpm or more, and further, the printed gloss of the printed matter is reduced. A high-quality coated paper for printing is obtained.

In the present invention, pigment particles having a particle diameter of 2 μm or more are 5% or less of the total pigment particles, and the adhesive contains at least a styrene-butadiene latex having a butadiene component of 50% by mass or more. This is a coated paper having an adhesive ratio of 4 to 7 parts by mass.

<Paper making>
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 made 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.

To the raw material pulp, a filler generally used for papermaking can be added as an internal additive. Examples of the filler include inorganic fillers such as light calcium carbonate, talc, titanium dioxide, clay, calcined clay, synthetic zeolite, and silica, polystyrene particles, urea formalin resin, and the like.

Although the compounding quantity of a filler is not specifically limited, It is preferable to add so that it may become 2-9 mass% with the ash content in a base paper, and 3-7 mass% is more preferable. If the ash content exceeds 9% by mass, hydrogen bonding between the pulps is likely to be hindered, resulting in a paper with no stiffness. The base paper cannot withstand shrinkage during printing and drying, and creases are likely to occur. When the ash content is less than 2% by mass, the pulp fibers are easily bonded by hydrogen bonding, and the shrinkage of the coated paper is liable to increase during drying after printing, and wrinkles are likely to occur. However, in the present invention, as described later, as a pigment of the coating layer, styrene-containing particles having a particle diameter of 1.0 μm or more are 5% or less of the total pigment, and the adhesive has a butadiene component of 50% by mass or more. By containing 4 to 7 parts by mass of the butadiene latex with respect to 100 parts by mass of the pigment, it is particularly easy to suppress the generation of wrinkles. Therefore, even if the filler content is out of the above range, the generation of wrinkles is suppressed. Easy coated paper is obtained. The ash content of the present invention is a value measured according to JISP8251 “Paper, paperboard and pulp-ash content test method—525 ° C. combustion method”.

<Regenerated particles>
In the present invention, it is preferable to use a filler having a particularly high porosity as the filler of the base paper in order to increase the porosity of the base paper and easily suppress creases. Examples of the filler having a high porosity include gargle-shaped particles and rosetta-shaped particles formed by agglomerating primary particles to form secondary particles.In the present invention, paper sludge is the main raw material, It is preferable to use regenerated particles obtained through a dehydration step, a drying step, a heat treatment step of at least three steps, and a pulverization step. By containing the recycled particles in the base paper, a base paper and a coated paper that have particularly high porosity and are easy to prevent wrinkles can be obtained. That is, since the regenerated particles obtained by this production method generate less hard material due to over-baking, the content of hard material inferior in voidability and wrinkle prevention effect can be suppressed even in the base paper, and the wrinkle prevention effect is improved. Easy to apply uniformly. Since the regenerated particles obtained without passing through the drying step and the at least three heat treatment steps contain a large amount of hard material, it is difficult to obtain a sufficient anti-wrinkle effect around the hard material. Since it becomes easy to generate | occur | produce, it is not preferable.

  The above-mentioned “recycled particles” are used as a main raw material by using papermaking sludge as a main raw material, and preferably a deinking floss containing a filler or a pigment separated from pulp fibers in a deinking process of waste paper processing equipment. Is recycled through dehydration, drying, combustion, and pulverization processes. In addition, the “papermaking sludge” refers to the solids that flowed out through the wire in the papermaking process, the solids collected from the wastewater generated in the washing process in the pulping process, and the precipitation / floating action in the wastewater treatment process. The solid content separated or recovered by the solid content separator or the solid content removed in the used paper processing step is mixed. The regenerated particles may be particles made of a single material or particles made of a plurality of materials.

  The proportion of silica contained in the regenerated particles depends on the volume average particle diameter of the regenerated particles and their elemental composition, but the upper limit is preferably 35% by mass in terms of oxide, more preferably 30% by mass, and even more preferably 20% by mass. preferable. On the other hand, the lower limit is preferably 9% by mass. Similarly, the upper limit of the proportion of calcium contained in the regenerated particles is preferably 82% by mass in terms of oxide, while the lower limit is preferably 30% by mass, more preferably 40% by mass, and 60% by mass. Further preferred. Similarly, the upper limit of the proportion of aluminum contained in the regenerated particles is preferably 35% by mass in terms of oxide, more preferably 30% by mass, and even more preferably 20% by mass. On the other hand, the lower limit is preferably 9% by mass. Each of the above components can be calculated by performing an elemental analysis at an acceleration voltage of 15 KV using an X-ray microanalyzer (model number: E-MAX · S-2150) manufactured by Horiba.

  Examples of a method for adjusting the mass ratio of silica, calcium and aluminum contained in the regenerated particles to the above ratio include, for example, a method for adjusting the raw material composition of the deinking floss, a first heat treatment step, a second heat treatment step, and a second method described later. The method of adding the coating floss and the adjustment process floss whose origin is clear in 3 heat treatment processes with a spray etc., the method of adding incinerator scrubber lime, etc. are mentioned. Specifically, in order to adjust the amount of silica contained in the regenerated particles, for example, waste water sludge from a newsprint manufacturing system in which a large amount of white carbon or the like is blended as an opacity improver may be used. For example, neutral papermaking wastewater sludge or coated paper manufacturing process wastewater sludge may be used. To adjust the amount of aluminum, for example, an acid papermaking sulfate band is used. What is necessary is just to use suitably the drainage sludge of the papermaking type | system | group currently used, and the wastewater sludge in the high quality papermaking process with much talc. In addition, although the manufacturing method of this regenerated particle is explained in full detail later, in the manufacturing method of the said coated paper, by using the regenerated particle obtained through a drying process and a heat treatment process of at least 3 steps, Opacity, white paper gloss, printing gloss, wrinkle resistance, etc. are improved.

[Silica composite regenerated particles]
The regenerated particles are preferably silica composite regenerated particles obtained by combining silica on the surface of the regenerated particles. By combining silica on the surface of the regenerated particles, the binding between the pulp fibers is moderately hindered by the cationic property of the regenerated particles and the anionic property of the silica, improving the wrinkle resistance of the resulting coated paper Can do. In addition, by combining silica, the irregularity of the particles is further improved, so that binding between pulp fibers is easily inhibited, and coated paper that can further prevent wrinkles can be easily obtained, which is preferable. In addition, if the regenerated particles are obtained through a drying step and at least three heat treatment steps, the generation of hard materials due to overcalcination is reduced, so that uniform wrinkle resistance can be obtained. preferable. The silica composite regenerated particles are preferable because the surface of the porous regenerated particles is originally composed of silica and has excellent opacity, so that the opacity of the resulting coated paper is easily improved.

  The silica contained in the silica composite regenerated particles can be used without particular limitation as long as it is a synthetic silica obtained by some chemical reaction. Examples of such synthetic silica include colloidal silica, silica gel, and anhydrous silica. These synthetic silicas have excellent properties such as high specific surface area, high gas adsorbing ability, fineness, permeability to pores and large adsorbing power, high adhesion, or high oil absorption. . Among these synthetic silicas, for example, colloidal silica is an anhydrous silicic acid sol obtained by removing impurities from a silicic acid compound, and adjusting the pH and concentration to stabilize the sol. It means amorphous silica having a shape such as a regular shape. Silica gel means hydrous silicic acid obtained by decomposing sodium silicate with an inorganic acid. Anhydrous silica means that obtained by hydrolysis of silicon tetrachloride. These silicas may be used individually by 1 type, and may be used in combination of 2 or more type.

  Although the ratio of the silica contained in the said silica composite reproduction | regeneration particle | grains is dependent on the volume average particle diameter of the reproduction | regeneration particle | grains and its element structure, it is preferable to set it as 10 to 50 mass% in conversion of an oxide, and 41 mass% The content is more preferably 49% by mass or less, and further preferably 42% by mass or more and 48% by mass or less. By setting the ratio of silica contained in the silica composite regenerated particles within the above range, the wrinkle resistance of the coated paper using the silica composite regenerated particles can be further improved.

  The proportion of calcium contained in the silica composite regenerated particles is preferably 30% by mass or more and 80% by mass or less in terms of oxide, and the proportion of aluminum contained in the silica composite regenerated particles is in terms of oxide. The content is preferably 7% by mass or more and 20% by mass or less. Each of the above components can be calculated by performing an elemental analysis at an acceleration voltage of 15 KV using an X-ray microanalyzer (model number: E-MAX · S-2150) manufactured by Horiba.

  Moreover, since the said silica composite reproduction | regeneration particle | grains coat | cover the surface of the filler with silica, it can reduce the wear of the wire (net | network part) of a papermaking process, and can extend the lifetime of a wire. If the filler particles added to the paper are hard, the wire of the paper machine is likely to be damaged, and this is not preferable because it shortens the life of the wire. However, since the silica composite regenerated particles have an appropriate hardness, the wear of the wire is reduced. Can extend the lifespan.

<Method for producing regenerated particles>
Here, the above-described method for producing regenerated particles will be described in detail with reference to FIGS. 1 mainly includes a storage tank 21, a drying device 22, a first heat treatment furnace (external heat kiln furnace) 24, a second heat treatment furnace (external heat kiln furnace) 25, and a third heat treatment furnace (inside Thermal kiln furnace) 27 is provided. This method for producing regenerated particles has a drying step and a heat treatment step of at least three stages. The papermaking sludge as the raw material 20 is sent from the storage tank 21 to the drying device 22 including the burner 36A and the hot air generating furnace 36, and then sent from the supply port 24A to the first heat treatment furnace 24 via the charging machine 23. The raw material 20 heat-treated in the first heat treatment furnace 24 including the burner 37A and the hot air generating furnace 37 is discharged from the discharge port 24B, and is supplied to the second heat treatment furnace 25 from the supply port 25A. The raw material 20 heat-treated in the second heat treatment furnace 25 provided with the burner 38A and the hot air generating furnace 38 is discharged from the discharge port 25B, and subsequently supplied to the third heat treatment furnace 27 from the supply port 27A. The raw material 20 heat-treated in the third heat treatment furnace 27 including the burner 39A and the hot air generating furnace 39 is discharged from the discharge port 27B, and stored in the silo 30 through the cooler 28 and the particle size selector 29. Further, the combustion gas discharged from the discharge port 25B of the second heat treatment furnace 25 is discharged from the chimney 35 through the recombustion chamber 31, the precooler 32, the heat exchanger 33, and the induction fan 34. In addition, if necessary, it may have a dehydration process and a disentangling process to be described later before the drying process, or may have a grinding and sorting process to be described later after the third heat treatment process. .

  The method for producing regenerated particles described in detail below is preferably set so that the heat treatment temperature is increased in the order of the drying step, the first heat treatment step, the second heat treatment step, and the third heat treatment step. Recycled particles with uniform quality can be stably produced by drying 20 with a hot air stream. Further, by separately performing the drying process and the three stages of the heat treatment process, the heat treatment temperature according to the purpose can be reliably distinguished and controlled.

[Raw material]
It is preferable that the raw material 20 for regenerated particles contains the above-mentioned papermaking sludge in an amount of 50% by mass or more in terms of solid content. It is preferable to use the paper sludge having a stable quality in which used paper pulp is selected or selected in the used paper pulp manufacturing process or the like. As a result, it is possible to prevent plastics such as vinyl and film, which cause fluctuations in the unburned rate, and the type, ratio, amount, etc., of inorganic substances derived from the above-mentioned waste paper pulp manufacturing process are constant, and recycled particles The raw material 20 suitable for manufacture of can be obtained.

  Further, if the raw material 20 contains iron, it causes a decrease in the whiteness of the obtained regenerated particles. Therefore, it is preferable to selectively remove iron in advance. Specifically, the equipment used in each process is designed or lined with materials other than iron to prevent iron from being mixed into the system due to wear, etc., or high magnetic materials such as magnets are installed in each equipment. In this case, it is possible to selectively remove iron.

[Dehydration process]
Since the raw material 20 generally contains 95% by mass to 98% by mass of water, it is preferable to perform a dehydration process using a known dehydration apparatus. In the dehydration treatment, the raw material 20 is dehydrated to a moisture content of 65% by mass or more and 90% by mass or less by, for example, a screen, and then the upper limit of the moisture content by a screw press or the like is 60% by mass, preferably 50% by mass, more preferably. Dehydration to 45% by mass and 30% by mass as a lower limit of the moisture content, preferably 35% by mass can be mentioned. Here, the moisture content is a value calculated by the following formula using the mass at the time when the raw material 20 is dried using a known constant temperature dryer and no mass fluctuation is recognized as the mass after drying.
(Equation 1)
Moisture content (mass%) = (mass before drying−mass after drying) ÷ mass before drying × 100

  By performing the dehydration process in this way, the outflow of inorganic substances is suppressed, energy loss in the subsequent drying process and heat treatment process is suppressed, drying unevenness is prevented, and the floc of the raw material 20 becomes too hard to be easily understood. This can be suppressed. In the dehydration step, an auxiliary agent such as a flocculant for aggregating the raw material 20 can be added to improve the dehydration efficiency, but it should be noted that an auxiliary agent that does not contain iron is used. This is because if the assistant contains iron, the whiteness of the regenerated particles obtained may be reduced.

[Unraveling process]
The raw material 20 after the dehydration step may be cut out from the storage tank 21 and subjected to the unraveling step. In the unraveling step, for example, the raw material 20 may be unraveled using a known device such as a stirrer or a mechanical roll. 70 mass% is preferable as the upper limit of the ratio of the particle diameter of 50 mm or more of the raw material 20 after a cracking process. On the other hand, the lower limit of the ratio of the particle diameter of 50 mm or more is preferably 30% by mass, more preferably 40% by mass, and further preferably 50% by mass. The “ratio of particle diameter of 50 mm or more” means the mass ratio of the raw material 20 that did not pass through the sieve having a 50 mm pore in the entire raw material 20, and JIS-Z8801-2 (2000) “Sieving for test—Part 2 : Metal plate sieve ”. By performing the cracking process in this way, a raw material 20 having a particle size suitable for the subsequent drying process can be obtained.

[Drying process]
The raw material 20 after the dehydration step is subjected to the above-described unraveling step and then subjected to a drying step. As the drying device 22 used in the drying process, it is preferable to use an air flow drying device capable of drying the raw material 20 accompanied by a hot air flow. This airflow drying apparatus can dry the raw material 20 and simultaneously unravel the raw material 20 by the large dispersion force of the hot airflow. In addition, the raw material 20 is discharged from the drying device 22 at the next moment when the water is evaporated. This is because there is no possibility of unintended pyrolysis and combustion of organic matter. Examples of the drying device 22 include known devices such as a trade name “Kudakera” manufactured by Shin Nippon Kaihe Heavy Industries Co., Ltd., and an air flow drying device obtained by improving them. In the drying process in the present embodiment, the raw material 20 after dehydration is supplied from the storage tank 21 to the drying device 22, and hot air is blown from the hot air generating furnace 36 including the burner 36 </ b> A, and is accompanied by the hot air flow generated by the hot air. The raw material 20 is dried. By controlling the hot air flow by adjusting the temperature, flow rate, flow rate and the like of the hot air in this dehydration step, the dry state and the unfolded state of the raw material 20 can be adjusted.

  After the drying step, the raw material 20 having a particle diameter of 50 mm or more does not exist, and the upper limit of the average particle diameter is preferably 7 mm, more preferably 5 mm, and even more preferably 3 mm. On the other hand, the lower limit of the average particle diameter is preferably 1 mm. “Average particle size” is based on JIS-Z8801-2 (2000) “Sieving for test-Part 2: Metal plate sieve” and sieved with different sieves. The mass of the processed object is measured, and the total value of the measured values is the size of the mesh opening in the stage corresponding to 50% by mass of the whole, and the “ratio of particle diameter of 50 mm or more” is as described above. is there. By performing the drying step in this manner, the energy cost in the subsequent heat treatment step can be suppressed, and the raw material 20 can be uniformly heat-treated from the surface portion to the core portion.

  The temperature of the hot air flow in the drying step is not particularly limited. For example, the upper limit of the hot air temperature from the hot air generator 36 is 600 ° C., preferably 500 ° C., more preferably 400 ° C., and the lower limit of the hot air temperature. As 200 ° C., preferably 300 ° C. Moreover, the temperature of the exhaust gas from the drying device 22 is preferably 500 ° C. or less, more preferably 400 ° C. or less, and further preferably 300 ° C. or less. By setting the temperature of the hot air stream and the exhaust gas in the drying step within the above ranges, the raw material 20 having a uniform moisture content suitable for producing regenerated particles can be obtained in as little as 1 to 3 seconds.

  The upper limit of the moisture content of the raw material 20 after the drying step is preferably 5%, more preferably 3%, and even more preferably 1%. On the other hand, the lower limit of the moisture content is preferably 0%. By setting the moisture content of the raw material 20 after the drying step within the above range, the heat treatment in the subsequent heat treatment step (especially the first heat treatment step) is more effectively performed without unevenness, and the regenerated particles having uniform quality are stabilized. Can be obtained. Moreover, by performing the said drying process and the following 1st heat processing processes separately, the heat processing temperature according to the objective can be distinguished and controlled reliably.

[Heat treatment process]
[First heat treatment step]
In the first heat treatment step, the raw material 20 that has passed through the drying step is charged into the first heat treatment furnace 24 by the charging machine 23. As this 1st heat processing furnace 24, a well-known heat processing furnace can be used suitably, for example, a fluidized-bed furnace, a stalker furnace, a cyclone furnace, a semi-dry distillation / negative pressure combustion type furnace etc. are mentioned. In the present embodiment, an external heat kiln furnace in which the furnace body is placed horizontally and rotates around the central axis is adopted as the first heat treatment furnace 24, but an internal heat kiln furnace or an internal heat is used instead of the external heat kiln furnace. It is also possible to use a combined kiln furnace with external heat. In the present embodiment, since the raw material 20 is dried and moisture is removed in advance prior to the first heat treatment step, the external heat kiln furnace is preferable in that the heat treatment temperature can be reliably controlled. In addition, the kiln furnace can easily adjust the degree of combustion of the raw material 20, is excellent in the yield of the raw material 20, and can be sufficiently stirred, so that there is no variation in the heat treatment of organic matter, and the obtained regenerated particles are uniform and excessive. This is also preferable in that the generation of hard materials by firing is small.

  In the present embodiment, the first heat treatment furnace 24 has a very gentle downward gradient in the conveyance direction, and the raw material 20 is gradually transferred in the conveyance direction by the downward gradient, the rotating action of the furnace body, and the gravitational action. It has a structure. An outer heat jacket 24C made of an electric heater or the like is provided on the outer surface of the first heat treatment furnace 24 in the present embodiment, and the raw material 20 deposited on the inner surface of the furnace body by the outer heat jacket 24C is indirect. Heated (external heat system). Further, the outer heat jacket 24C is divided into several pieces along the axial direction of the furnace body, and the heat treatment temperature can be finely controlled by individually heating the divided outer heat jacket. An accurate heat treatment according to 20 properties and conditions can be performed.

  The upper limit of the furnace body inner surface temperature of the first heat treatment furnace 24 is preferably 450 ° C, and more preferably 400 ° C. On the other hand, the lower limit of the furnace body inner surface temperature is preferably 260 ° C, more preferably 280 ° C, and further preferably 300 ° C. Further, the upper limit of the temperature inside the furnace body is preferably 350 ° C., and the lower limit of the temperature of the furnace body is preferably 240 ° C., more preferably 270 ° C., and further preferably 280 ° C. Thus, by setting the furnace body surface temperature and the furnace body temperature within the above ranges, the acrylic organic matter and cellulose contained in the raw material 20 can be sufficiently heat-treated (pyrolysis, etc.), and these are combusted. Excessive heating can be prevented. The furnace body inner surface temperature is a value measured by a thermocouple installed on the furnace body inner surface, and the furnace body temperature is a value measured by a thermocouple installed in the furnace body.

  Further, the first heat treatment furnace 24 may be, for example, an internal heat system that appropriately supplies hot air containing oxygen in addition to the above external heat system. In the case of the internal heating method, hot air may be supplied from the hot air generating furnace 37 provided with the burner 37A into the furnace body through the supply port 24A, and the hot air enters the discharge port 24B sequentially from the supply port 24A as the furnace body rotates. The raw material 20 to be transferred is heat-treated (cocurrent flow method). At this time, the gas in the first heat treatment furnace 24 is discharged as exhaust gas through the discharge port 24B. In such an internal heating method, the raw material 20 supplied to the first heat treatment furnace 24 can be immediately heated to a temperature suitable for thermal decomposition of acrylic organic matter, cellulose, or the like. In addition, since a temperature gradient is generated such that the temperature decreases toward the discharge port 24B, excessive heat treatment of the raw material 20 can be prevented. Such a temperature gradient can also be set by the above external heating method. The first heat treatment furnace 24 can use both the external heat method and the internal heat method. In the case of using both, the first heat treatment furnace 24 can be used in the first heat treatment furnace 24 using only the hot air generating furnace 37 without using the burner 37A. An oxygen-containing gas can be blown.

  In the case of the internal heating method, the upper limit of the oxygen concentration contained in the hot air to be supplied is preferably 20.0% by volume, more preferably 18.0% by volume. On the other hand, the lower limit of the oxygen concentration is preferably 5.0% by volume, more preferably 6.0% by volume, and even more preferably 7.0% by volume. The upper limit of the oxygen concentration of the exhaust gas is preferably 20.0% by volume, more preferably 17.0% by volume, and even more preferably 15.0% by volume. On the other hand, the lower limit of the oxygen concentration of the exhaust gas is preferably 0.1% by volume, more preferably 1.0% by volume, and even more preferably 3.0% by volume. The oxygen concentration is a value measured by an automatic oxygen concentration measuring device (model number: ENDA-5250, manufactured by Horiba Seisakusho). By setting the oxygen concentration contained in the hot air and the oxygen concentration of the exhaust gas within the above ranges, excessive heat treatment of the raw material 20 and ignition (combustion) of the pyrolysis gas are prevented, and acrylic organic matter, cellulose, etc. are sufficiently heat treated. It is possible to easily adjust the reduction rate of the calorific value described later. Further, by setting the oxygen concentration contained in the hot air and the oxygen concentration of the exhaust gas within the above ranges, the upper limit of the oxygen concentration in the furnace body is usually 20.0% by volume, preferably 17.0% by volume, more preferably 15%. On the other hand, the lower limit is usually adjusted to 0.1% by volume, preferably 1.0% by volume, more preferably 4.0% by volume. The oxygen concentration is the same in the case of the external heat method, and is the same in the case where the external heat method and the internal heat method are used in combination.

  In the case of the internal heat system, the upper limit of the temperature of the hot air supplied to the first heat treatment furnace 24 is preferably 420 ° C, more preferably 410 ° C, and further preferably 400 ° C. On the other hand, as said lower limit, 300 degreeC is preferable, 350 degreeC is more preferable, and 360 degreeC is further more preferable. Moreover, as an upper limit of the temperature of exhaust gas, 370 degreeC is preferable, 360 degreeC is more preferable, and 350 degreeC is further more preferable. On the other hand, the lower limit is preferably 250 ° C, more preferably 300 ° C, and still more preferably 310 ° C. Here, the temperature of the hot air is a value measured with a thermocouple of the hot air generating furnace 37, and the temperature of the exhaust gas is a value measured with a thermocouple installed in the flue of the exhaust gas. By setting the temperature of the hot air and the exhaust gas within the above range, the pyrolysis gas is prevented from being ignited, and the acrylic organic matter and cellulose in the raw material 20 are sufficiently decomposed and volatilized. Heat treatment control in the third heat treatment furnace 27 becomes easy, and it effectively suppresses the generation of carbides that cause a decrease in the whiteness of the regenerated particles and the generation of hard substances due to overcombustion. By gently heat-treating the organic matter, generation of residual carbon can be suppressed and generation of flame retardant carbon can be suppressed. Further, by setting the temperature of the hot air and the exhaust gas within the above range, the upper limit of the temperature in the furnace body is usually adjusted to 370 ° C., preferably 360 ° C., more preferably 350 ° C., while the lower limit is usually 250 ° C. , Preferably 300 ° C, more preferably 310 ° C. The temperature in the furnace body is a value measured by a thermocouple installed in the furnace body, and the temperature of the raw material 20 is estimated to be substantially the same as the temperature in the furnace body. The temperature in the furnace body is not uniform because there is a temperature gradient from the supply port 24A to the discharge port 24B. Therefore, it is preferable to control the temperature by adjusting the temperature of hot air and managing the temperature of exhaust gas.

  In the first heat treatment furnace 24, heat treatment is performed so that the calorific value of the raw material 20 is reduced by 20% to 90%, preferably 50% to 80%, and more preferably 50% to 70%. It is preferable. Thus, by making the decreasing rate of the emitted-heat amount into the said range, excessive heat processing can be suppressed and the production | generation of a hard substance can be suppressed to 1.5 mass% or less. Further, by setting the rate of decrease in the calorific value within the above range, the thermal decomposition of the styrene-based organic matter contained in the raw material 20 is prevented, the pyrolysis gas such as cellulose is ignited, and the residual acrylic organic matter that is a high calorific value component Can be effectively prevented. The rate of decrease in the heat generation amount is a value obtained by comparing the heat generation amount of the raw material 20 supplied to the first heat treatment furnace 24 with the heat generation amount of the raw material 20 discharged from the first heat treatment furnace 24. Is a value measured using a calorimeter (Nanken digital calorimeter, manufactured by Yoshida Seisakusho). In particular, in the first heat treatment furnace 24, acrylic organic matter and cellulose are removed to reduce the calorific value by 20% to 90%, and the calorific value is less than 1000 cal / g, preferably 300 cal / g to 400 cal / g. By performing the heat treatment in such a manner, it is possible to homogenize the regenerated particles that can be easily suppressed in the range of the temperature in the furnace body in the second heat treatment furnace 25 within the range of 10 ° C. or more and 40 ° C. or less. By setting the fluctuation range of the temperature inside the furnace body in the second heat treatment furnace 25 within the above range, variations in hardness and whiteness of the regenerated particles obtained can be prevented.

  As an upper limit of the unburned rate of the raw material 20 in the 1st heat processing furnace 24, 30 mass% is preferable, 26 mass% is preferable, and 23 mass% is more preferable. On the other hand, as a minimum of the above-mentioned unburned rate, 13 mass% is preferred, 14 mass% is preferred, and 15 mass% is more preferred. Here, the unburned rate is a value obtained by measuring a weight loss rate when burned in an electric furnace whose temperature is adjusted to about 600 ° C. for 2 hours. By setting the unburned rate of the raw material 20 in the above range, the subsequent heat treatment in the second heat treatment furnace 25 can be performed slowly while suppressing the energy cost.

  The upper limit of the residence time of the raw material 20 in the first heat treatment furnace 24 is preferably 120 minutes, more preferably 105 minutes, and further preferably 90 minutes. On the other hand, as a minimum of residence time, 30 minutes are preferred, 45 minutes are more preferred, and 60 minutes are still more preferred. By setting the residence time in the above range, the acrylic organic matter and cellulose contained in the raw material 20 can be slowly pyrolyzed, the generation of flame retardant carbon is suppressed, and the whiteness of the regenerated particles obtained is reduced. And increase of hard substance can be prevented. The residence time is an actually measured time from when a metal piece that can be identified by the color different from that of the raw material 20 is charged into the furnace body from the supply port 24A and discharged from the discharge port 24B.

By the first heat treatment step, an acrylic organic substance having a calorific value peak at around 220 ° C. and a high calorific value component derived from paper sludge such as cellulose having a calorific value peak at around 320 ° C. are removed from the raw material by heat treatment. Can do. As a result, excessive combustion in the subsequent second heat treatment step is suppressed, and generation of hard substances such as gelenite (Ca ₂ Al ₂ SiO ₇ ) and anorthite (CaAl ₂ Si ₂ O ₈ ) that are inappropriate as regenerated particles is suppressed. can do.

[Second heat treatment step]
The raw material 20 heat-treated in the first heat treatment furnace 24 is sent to the second heat treatment step and subjected to heat treatment such as pyrolysis and combustion.

  Prior to sending the raw material 20 to the second heat treatment step, the average particle diameter is preferably adjusted to 1 mm to 7 mm, preferably 1 mm to 5 mm, more preferably 1 mm to 3 mm.

  In the second heat treatment step, the raw material 20 is charged into the second heat treatment furnace 25. As the second heat treatment furnace 25, a known heat treatment furnace can be used, and examples thereof include a fluidized bed furnace, a stalker furnace, a cyclone furnace, a semi-dry distillation / negative pressure combustion type furnace, and the like. In this embodiment, as the second heat treatment furnace 25, an external heat kiln furnace in which the furnace body is placed horizontally and rotates around the central axis is adopted, but instead of the external heat kiln furnace, an internal heat kiln furnace or internal heat is used. It is also possible to use a combined kiln furnace with external heat. The second heat treatment furnace 25 of the present embodiment has the same shape as that of the first heat treatment furnace 24. For example, a raw material using a kiln furnace having a different axial length from the first heat treatment furnace 24 is used. The 20 residence times may be different. On the outer surface of the second heat treatment furnace 25 of the present invention, as in the first heat treatment furnace 24, an external heat jacket 25C made of an electric heater or the like is provided. The material 20 deposited on the substrate is indirectly heated (external heat system). Further, the outer heat jacket 25C is divided into several pieces along the axial direction of the furnace body, and the heat treatment temperature can be finely controlled by individually heating the divided outer heat jackets. It is possible to perform an accurate heat treatment according to the nature and state.

  The upper limit of the furnace body inner surface temperature of the second heat treatment furnace 25 is preferably 550 ° C, and more preferably 500 ° C. On the other hand, the lower limit of the furnace body inner surface temperature is preferably 360 ° C, more preferably 380 ° C, and still more preferably 400 ° C. Further, the upper limit of the temperature in the furnace body is preferably 400 ° C., and the lower limit of the temperature of the furnace body is preferably 360 ° C. Thus, by setting the furnace body inner surface temperature and the furnace body temperature within the above ranges, the styrene-based organic matter contained in the raw material 20 can be sufficiently heat treated (pyrolysis, etc.), and excessive heat treatment is prevented. be able to. The temperature of the raw material 20 is estimated to be substantially the same as the temperature in the furnace body. The method for measuring the furnace body inner surface temperature is the same as that for the first heat treatment furnace 24.

  In addition, the second heat treatment furnace 25 may be an internal heat method, similarly to the first heat treatment furnace 24. In the case of the internal heating method, hot air may be supplied from the hot air generating furnace 38 provided with the burner 38A into the furnace body through the supply port 25A, and sequentially enters the discharge port 25B from the supply port 25A by the hot air as the furnace body rotates. The raw material 20 to be transferred is heat-treated (cocurrent flow method). At this time, the gas in the second heat treatment furnace 25 is discharged as exhaust gas through the discharge port 25B. In such an internal heating system, the raw material 20 supplied to the second heat treatment furnace 25 can be immediately heated to a temperature suitable for thermal decomposition of styrene-based organic matter or the like. In addition, since a temperature gradient is generated such that the temperature decreases toward the discharge port 25B, excessive heat treatment of the raw material 20 can be prevented. In addition, the setting of such a temperature gradient is also possible by the above external heating method as in the first heat treatment furnace 24. The first heat treatment furnace 24 can use both the external heat method and the internal heat method. In the case of using both, the first heat treatment furnace 24 can be used in the second heat treatment furnace 25 using only the hot air generating furnace 38 without using the burner 38A. An oxygen-containing gas can be blown.

  Further, in the case where the first heat treatment furnace 24 is a parallel flow method, the counter heat flow method in which the second heat treatment furnace 25 blows hot air into the furnace main body from the discharge port 25B and discharges the exhaust gas through the supply port 25A. Good. As a result, the pipe through which the exhaust gas from the first heat treatment furnace 24 and the pipe through which the exhaust gas from the second heat treatment furnace 25 are passed can be combined into, for example, one, and the pipe processing becomes easy. Further, the first heat treatment furnace 24 and the second heat treatment furnace 25 are connected, and hot air from the hot air generation furnace 37 is supplied into the second heat treatment furnace 25 through the supply port 25A after passing through the first heat treatment furnace 24. At the same time, hot air containing oxygen from the hot air generating furnace 38 provided with the burner 38A may be supplied into the second heat treatment furnace 25 through the supply port 25A (cocurrent flow system).

  In the case of the internal heating method, the upper limit of the oxygen concentration contained in the hot air to be supplied is preferably 20.0% by volume, more preferably 18.0% by volume. On the other hand, the lower limit of the oxygen concentration is preferably 5.0% by volume, more preferably 6.0% by volume, and even more preferably 7.0% by volume. The upper limit of the oxygen concentration of the exhaust gas is preferably 20.0% by volume, more preferably 17.0% by volume, and even more preferably 15.0% by volume. On the other hand, the lower limit of the oxygen concentration is preferably 0.1% by volume, more preferably 1.0% by volume, and even more preferably 3.0% by volume. The oxygen concentration is a value measured with an automatic oxygen concentration measuring device (model number: ENDA-5250, manufactured by Horiba Seisakusho). By setting the oxygen concentration contained in the hot air and the oxygen concentration of the exhaust gas within the above ranges, excessive heat treatment of the raw material 20 and pyrolysis gas ignition (combustion) can be prevented, and styrenic organic matters can be sufficiently heat treated to generate heat. The reduction rate of the amount can be easily adjusted, the curing of the raw material 20 can be prevented, and the whitening of the raw material 20 can be promoted without increasing the equipment cost and the energy cost. Further, by setting the oxygen concentration contained in the hot air and the oxygen concentration of the exhaust gas within the above ranges, the upper limit of the oxygen concentration in the furnace body is usually 20.0% by volume, preferably 17.0% by volume, more preferably 15%. On the other hand, the lower limit is usually adjusted to 0.1% by volume, preferably 1.0% by volume, more preferably 4.0% by volume.

  In the case of the internal heating method, the upper limit of the temperature of the hot air supplied to the second heat treatment furnace 25 is preferably 550 ° C, more preferably 530 ° C, and further preferably 500 ° C. On the other hand, the lower limit is preferably 350 ° C., more preferably 380 ° C., and further preferably 400 ° C. Moreover, as an upper limit of the temperature of waste gas, 500 degreeC is preferable, 470 degreeC is more preferable, and 450 degreeC is further more preferable. On the other hand, the lower limit is preferably 300 ° C, more preferably 330 ° C, and even more preferably 350 ° C. Here, the temperature of the hot air is a value measured with a thermocouple of the hot air generating furnace 38, and the temperature of the exhaust gas is a value measured with a thermocouple installed in the flue flue. By setting the temperature of the hot air and the exhaust gas within the above ranges, the styrene-based organic matter in the raw material 20 is sufficiently pyrolyzed and volatilized, and the heat treatment control in the third heat treatment furnace 27 is facilitated later, and the whiteness of the regenerated particles is increased. It effectively suppresses the generation of carbides that cause the reduction of carbon dioxide and the generation of hard substances due to overcombustion, and also suppresses the generation of residual carbon by gently heat-treating organic substances such as styrenic organic substances and residual carbon. it can. Further, by slowly heat-treating the organic matter with the temperature of the hot air and the exhaust gas within the above range, the pulverization of the raw material 20 is suppressed, the formation of aggregates is promoted, and the heat treatment degree and the grain alignment of the raw material 20 are easy and stable. It is possible to prevent the variation of the unburnt ratio between the particle surface of the raw material 20 and the core. Further, by setting the temperature of the hot air and the exhaust gas within the above range, the upper limit of the temperature in the furnace body is usually adjusted to 500 ° C, preferably 470 ° C, more preferably 450 ° C, while the lower limit is usually 300 ° C. , Preferably 330 ° C., more preferably 350 ° C. The temperature in the furnace body is a value measured by a thermocouple installed in the furnace body, and the temperature of the raw material 20 is estimated to be substantially the same as the temperature in the furnace body. Note that the temperature in the furnace body is not uniform and has a temperature gradient from the supply port 25A to the discharge port 25B as in the first heat treatment furnace 24, and therefore is controlled by adjusting the temperature of hot air and managing the temperature of exhaust gas. It is preferable.

  The exhaust gas discharged from the second heat treatment furnace 25 can be recombusted by a burner or the like in the recombustion chamber 31, precooled by the precooler 32, and then discharged from the chimney 35 by the induction fan 34 through the heat exchanger 33. Here, the heat exchanger 33 raises the temperature of the outside air, and the heated outside air can be used for, for example, hot air blown into the first heat treatment furnace 24 to recover heat of the exhaust gas. Such exhaust gas treatment is also effective for removing harmful substances contained in the exhaust gas.

  The upper limit of the residence time of the raw material 20 in the second heat treatment furnace 25 is preferably 120 minutes, more preferably 100 minutes, and even more preferably 80 minutes. On the other hand, as a minimum of residence time, 30 minutes are preferred and 40 minutes are more preferred. By setting the residence time within the above range, the styrenic organic matter contained in the raw material 20 can be slowly pyrolyzed, the production of flame retardant carbon is suppressed, the whiteness of the regenerated particles obtained is reduced, and the hard substance Can be prevented from increasing.

  The upper limit of the unburned rate of the raw material 20 in the second heat treatment furnace 25 is preferably 20% by mass, preferably 17% by mass, and more preferably 12% by mass. On the other hand, the lower limit of the unburned rate is preferably 2% by mass, more preferably 5% by mass, and more preferably 7% by mass. Here, the unburned rate is a value obtained by measuring a weight loss rate when burned in an electric furnace whose temperature is adjusted to about 600 ° C. for 2 hours. By setting the unburned rate of the raw material 20 in the above range, it is possible to prevent the raw material 20 from being cured while suppressing the energy cost, and to efficiently perform the heat treatment (combustion) in the third heat treatment furnace 27 in a short time. The whiteness of the regenerated particles obtained can be 70% or more, preferably 80% or more.

By the second heat treatment step, styrenic organic matter having a calorific value peak around 420 ° C. derived from papermaking sludge can be pyrolyzed and removed. As a result, excessive combustion in the subsequent third heat treatment step is suppressed, and generation of hard substances such as gerenite (Ca ₂ Al ₂ SiO ₇ ) and anorsite (CaAl ₂ Si ₂ O ₈ ) that are inappropriate as regenerated particles is suppressed. Thus, regenerated particles having excellent whiteness can be obtained uniformly and stably.

[Third heat treatment step]
The raw material 20 heat-treated in the second heat treatment furnace 25 is sent to the third heat treatment step and subjected to heat treatment such as pyrolysis and combustion.

  Prior to sending the raw material 20 to the third heat treatment step, the average particle diameter is preferably adjusted to 5 mm or less, preferably 1 mm to 4 mm, more preferably 1 mm to 3 mm. By setting the average particle size in the above range, over-burning of the raw material 20 in the third heat treatment furnace 27 can be prevented, the remaining carbon can be easily heat-treated (burned), and the combustion progresses to the core to reproduce with high whiteness. Particles can be obtained.

  The particle size of the raw material 20 supplied to the third heat treatment step is such that the ratio of the particle diameter of 1 mm or more and 5 mm or less is 70% by mass or more, preferably 75% by mass or more and 95% by mass or less. More preferably, it is preferably 80% by mass or more and 95% by mass or less because the remaining carbon can be easily heat-treated (burned) and regenerated particles with high whiteness can be obtained by the combustion progressing to the core.

  In the third heat treatment step, the raw material 20 is charged into the third heat treatment furnace 27 from the charging machine 26. As the third heat treatment furnace 27, a known heat treatment furnace can be used, and examples thereof include a fluidized bed furnace, a stalker furnace, a cyclone furnace, a semi-dry distillation / negative pressure combustion type furnace, and the like. In the present embodiment, as the third heat treatment furnace 27, an internal heat kiln furnace in which the furnace body is placed horizontally and rotates around the central axis is preferable because the heat treatment efficiency is superior to the external heat kiln furnace. Similarly to the 24 and the second heat treatment furnace 25, an external heat kiln furnace having an external heat jacket can also be used. The outer heat jacket is preferably of an electric heater type in which the temperature control in the longitudinal direction (conveyance direction, the axial direction of the furnace body) is easy, and thus a temperature gradient is arbitrarily provided if the temperature control is easy in the longitudinal direction. This is preferable in that the raw material 20 can be maintained at a predetermined temperature for a predetermined time, and residual organic components and residual carbon contained in the raw material 20 can be removed as close to zero as possible. When an external heat kiln furnace is employed as the third heat treatment furnace 27, the raw material 20 can be heat-treated with a predetermined residence time, and the uniform heat is indirectly applied to the raw material 20, so that the combustion becomes uniform. Since the raw material 20 is gently agitated by the friction caused by the rotation of the inner surface of the furnace, fine particles are hardly generated, and regenerated particles having stable quality and properties can be obtained.

  In the third heat treatment furnace 27, the regenerative particles obtained can be homogenized by controlling the conveying speed of the raw material 20 with various lifters provided on the inner wall of the furnace main body and slowly heat-treating the raw material 20. Various lifters provided on the inner wall of the furnace main body are not particularly limited. For example, on the inner wall in the third heat treatment furnace 27, the raw material 20 is supplied from the supply port 27 </ b> A side to the discharge port 27 </ b> B side in FIGS. And the like, and / or a plurality of parallel lifters 51 parallel to the axis are provided in this order.

  In the present embodiment, the third heat treatment furnace 27 is configured to be rotationally driven by a rotational drive means (not shown), and is provided with a supply port 27A at one end and a discharge port 27B at the other end. A combustion burner (not shown) for introducing combustion gas into the outer casing 52 is disposed at the other end or both ends. On the inner surface of the fire wall 53 on the supply port 27 </ b> A side of the outer casing 52, a plurality of spiral lifters 50 having an inclination angle of 45 ° or more and 70 ° or less with respect to the axial center of the outer casing 52 via the mounting bracket 54. At the other end side, a parallel lifter 51 parallel to the axis of the outer casing 52 is projected in the circumferential direction via a mounting bracket 55.

  In addition, it is preferable to comprise the fireproof wall 53 with a fireproof castable or a fireproof brick, etc. Moreover, it is expensive by making the spiral lifter 50 and the parallel lifter 51 into metal, such as a stainless steel plate which has heat resistance, for example. Sufficient durability and strength can be secured without using a heat-resistant material. Moreover, since these lifters have higher heat transfer efficiency than refractory lifters, the heat efficiency can be further improved. In particular, the spiral lifter 50 and the parallel lifter 51 are desirably arranged in this order from the supply port 27A to the discharge port 27B of the combusted material as described above.

  According to the third heat treatment furnace 27 configured as described above, the content charged from the supply port 27A is lifted and dropped while being fed by the spiral lifter 50 toward the other end by an appropriate amount. In addition, the combustion gas (combustible gas) generated by gasification of the organic component derived from the raw material 20 at the time of dropping can be efficiently brought into contact with the falling object. Furthermore, since it is further efficiently brought into contact with the combustion gas (combustible gas) by repeating the operation of being lifted and dropped by the parallel lifter 51, the contents can be combusted efficiently. In particular, by controlling the amount of the content fed into the parallel lifter 51 by the spiral lifter 50, the content is lifted and dropped properly at the parallel lifter 51, and the combustion of the content is uniform and efficient. Can be done automatically. Further, since there is no fear of damage to the refractory, there is no decrease in the purity of the fired product, and its production capacity can be improved.

  In the above embodiment, the spiral lifter 50 and the parallel lifter 51 are provided side by side, but only one of them may be provided as necessary. Further, these lifters can be applied as appropriate to the first heat treatment furnace and the second heat treatment furnace.

  When the third heat treatment furnace 27 is of the internal heating type, hot air may be supplied from the hot air generating furnace 39 provided with the burner 39A into the furnace main body through the supply port 27A, and the hot air is used to rotate the furnace main body from the supply port 27A. Accordingly, the heat treatment of the raw material 20 sequentially transferred to the discharge port 27B is performed (cocurrent flow method). At this time, the gas in the third heat treatment furnace 27 is discharged as exhaust gas through the discharge port 27B, for example. Moreover, it is good also as a counter-current system which blows in hot air through the discharge port 27B of the raw material 20, and discharge | emits the gas (exhaust gas) in the 3rd heat processing furnace 27 through the supply port 27A. When the countercurrent system is used in this way, it is possible to prevent the dust in the exhaust gas from being mixed into the raw material 20 and to prevent the quality of the regenerated particles obtained from being deteriorated. That is, the residual carbon contained in the raw material 20 is immediately combusted, and soot generated as a result of the combustion of the residual carbon is quickly discharged out of the furnace body from the supply port 27A together with the exhaust gas, and is thus discharged from the discharge port 27B. Mixing into the raw material 20 can be prevented. In the case where the third heat treatment furnace 27 is an external heating system, for example, an oxygen-containing gas may be blown into the third heat treatment furnace 27 using only the hot air generating furnace 39 without using the burner 39A.

  When the third heat treatment furnace 27 is of the internal heat system, the upper limit of the oxygen concentration contained in the supplied hot air is preferably 20.0% by volume, more preferably 18.0% by volume. On the other hand, the lower limit of the oxygen concentration is preferably 5.0% by volume, more preferably 6.0% by volume, and even more preferably 7.0% by volume. Further, the upper limit of the oxygen concentration of the exhaust gas is preferably 20.0% by volume, more preferably 17.0% by volume, and further preferably 15.0% by volume. On the other hand, the lower limit of the oxygen concentration of the exhaust gas is preferably 0.1% by volume, more preferably 1.0% by volume, and even more preferably 3.0% by volume. The oxygen concentration is a value measured by an automatic oxygen concentration measuring device (model number: ENDA-5250, manufactured by Horiba Seisakusho). By setting the oxygen concentration contained in the hot air and the oxygen concentration of the exhaust gas within the above ranges, excessive heat treatment of the raw material 20 and ignition (combustion) of the pyrolysis gas are prevented, and compressed air and additional equipment are not required. Residual carbon and residual organic matter can be sufficiently heat-treated, and whitening of the regenerated particles can be promoted. Further, by setting the oxygen concentration contained in the hot air and the oxygen concentration of the exhaust gas within the above ranges, the upper limit of the oxygen concentration in the furnace body is usually 20.0% by volume, preferably 17.0% by volume, more preferably 15%. On the other hand, the lower limit is usually adjusted to 0.1% by volume, preferably 1.0% by volume, more preferably 4.0% by volume.

  Moreover, when the 3rd heat processing furnace 27 is an internal heating system, as an upper limit of the temperature of the hot air supplied, 780 degreeC is preferable, 750 degreeC is more preferable, 720 degreeC is further more preferable. On the other hand, the lower limit is preferably 550 ° C, more preferably 600 ° C, and further preferably 650 ° C. Moreover, as an upper limit of the temperature of exhaust gas, 780 degreeC is preferable, 750 degreeC is more preferable, and 720 degreeC is further more preferable. On the other hand, the lower limit is preferably 550 ° C, more preferably 600 ° C, and further preferably 650 ° C. Here, the temperature of the hot air is a value measured by a thermocouple of the hot air generating furnace 39, and the temperature of the exhaust gas is a value measured by a thermocouple installed in the flue flue. By setting the temperature of the hot air and the exhaust gas within the above range, the residual carbon and residual organic matter in the raw material 20 are sufficiently heat-treated, and by slowly heat-treating the organic matter, the pulverization of the raw material 20 is suppressed and at the same time Formation can be promoted, and the heat treatment degree and grain alignment of the raw material 20 can be easily and stably controlled. In addition, by setting the temperature of the hot air and the exhaust gas within the above range, it is possible to prevent the combustion from proceeding locally earlier than the particle alignment of the raw material 20 proceeds, and the difference in the unburned rate between the particle surface and the core portion. Can be made uniform and the resulting regenerated particles can be prevented from clumping when slurried. By setting the temperature of the hot air and the exhaust gas within the above range, the upper limit of the temperature in the furnace body is usually adjusted to 780 ° C., preferably 750 ° C., more preferably 720 ° C., while the lower limit is usually 550 ° C., preferably Is adjusted to 600 ° C, more preferably 650 ° C. The temperature in the furnace body is a value measured by a thermocouple installed in the furnace body, but the temperature in the furnace body is the same as that of the first heat treatment furnace 24 and the second heat treatment furnace 25. Since there is a temperature gradient from 27A to the outlet 27B and it is not uniform, it is preferable to control by adjusting the temperature of hot air and managing the temperature of exhaust gas.

  On the other hand, when the third heat treatment furnace 27 is an external heating system, the upper limit of the furnace body outer surface temperature is 780 ° C., preferably 750 ° C., more preferably 720 ° C., while the lower limit is 550 ° C. It is preferable to control the temperature of the external heat jacket or the like so that the temperature is preferably 600 ° C., more preferably 650 ° C. By setting the temperature of the outer surface of the furnace main body within the above range, residual carbon and residual organic matter such as styrene-acryl and styrene that could not be burned in the second heat treatment furnace 25 can be burned sufficiently. In addition, since the temperature of the inner surface of the furnace body is linked with the temperature of the outer surface of the furnace body, the temperature is substantially the same as the temperature of the outer surface of the furnace body. By controlling the temperature of the outer surface of the furnace body, it is estimated that the temperature is substantially the same as the temperature of the outer surface and the inner surface of the furnace body.

  The upper limit of the residence time of the raw material 20 in the third heat treatment furnace 27 is preferably 240 minutes, and more preferably 150 minutes. On the other hand, as a minimum of residence time, 60 minutes are preferred, 90 minutes are more preferred, and 120 minutes are still more preferred. By setting the residence time in the above range, the residual organic matter and residual carbon contained in the raw material 20 can be combusted sufficiently, the increase of the cured substance is suppressed, and the regenerated particles having excellent whiteness are stably produced. Will be able to.

By the third heat treatment step, organic substances such as residual carbon contained in the raw material 10 can be efficiently removed by heat treatment. Moreover, since overcombustion can be suppressed in the third heat treatment step, generation of hard substances such as gehlenite (Ca ₂ Al ₂ SiO ₇ ) and anorthite (CaAl ₂ Si ₂ O ₈ ) that are inappropriate as regenerated particles is generated. Thus, regenerated particles having excellent whiteness can be obtained uniformly and stably.

  In the internal heat or external heat kiln furnace used as the heat treatment furnace in the first to third heat treatment steps, the refractory constituting the inner wall can be formed in a circumferential shape (cylindrical shape), a hexagonal shape, an octagonal shape, or the like. In order to simply stir the raw material 20, it is preferable to adopt a configuration in which the refractory or the like is formed in a cylindrical shape and provided with a lifter as described above. By configuring the heat treatment furnace in such a configuration, the raw material 20 can be lifted and sufficiently stirred without sliding.

The "curing substance" is used as a coating pigment because it causes wear and damage to papermaking tools and stains in the papermaking system when used as a papermaking filler, even though it has a high hardness and a very small amount. In this case, it is a substance that causes wear, damage, or streak of coating equipment such as a doctor. Specifically, gehlenite (Ca ₂ Al ₂ SiO ₇ ) or anorsite (CaAl ₂ Si ₂ O _8). ) And the like. This is because the papermaking sludge that is the main component of the raw material 20 contains a large amount of inorganic substances such as calcium carbonate, kaolin, talc, and aluminum sulfate as a papermaking aid. Among these, for example, calcium carbonate (CaCO ₃ ) decreases in mass at a temperature of 600 ° C. or higher and 750 ° C. or lower during heat treatment, and changes to hard and water-soluble calcium oxide (CaO). ₂ Si ₂ O ₅ (OH) ₄ ) is reduced in mass by dehydration at around 500 ° C., becomes metakaolin, and changes to hard mullite (Al ₂ Si ₂ O ₁₃ ) at a high temperature around 1000 ° C. In addition, talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ) decreases in mass around 900 ° C. and changes to enstatite (MgSiO ₃ ). These changes can be confirmed by analysis of combustion products by differential thermothermogravimetric analysis (TG / DTA6200) and X-ray diffraction (RAD2X). Moreover, it can be confirmed by X-ray diffraction (RAD2X) that gehlenite and anorthite are present in the combustion product after the heat treatment. These gehlenite and anorthite occur even when the heat treatment temperature is around 500 ° C., and the amount of production increases with an increase in the heat treatment temperature. Moreover, when the calcium content in terms of oxide in papermaking sludge increases, anorthite decreases and gehlenite tends to increase. Anorsite is easily generated by the mixed combustion of calcium oxide and kaolin caused by overcombustion of calcium carbonate. Therefore, in the above-mentioned various heat treatment steps, the weight loss ratio in the differential thermothermal gravimetric analysis at 25 ° C. to 800 ° C. It is preferable to perform heat treatment so as to be 5% (TG) or more and suppress the formation of calcium oxide as much as possible. Further, since calcium hydroxide is easier to produce anorthite than calcium oxide, it is preferable to strictly adjust the dehydration rate (water content) of the raw material 20 and the oxygen concentration in various heat treatments. In addition, since silica has an action of promoting the formation of gehlenite and anorthite, it is preferable to reduce the silica contained in the raw material 20 as much as possible. For this purpose, for example, used newspaper and newspaper papermaking systems. By suppressing the use of white water, it is possible to suppress the production of relatively low melting point gelenite and anorthite, and to coat the obtained regenerated particles with silica.

[Crushing and sorting process]
The raw material 20 discharged from the third heat treatment furnace 27 is pulverized so as to have an average particle size of 15.0 μm or less, preferably 0.1 μm or more and 10.0 μm or less, more preferably 1.0 μm or more and 5.0 μm or less. It is preferable to adjust the average particle size. The average particle diameter after pulverization is a volume average particle diameter (D50) measured using a particle size distribution diameter (model number: SALD-2200, manufactured by Shimadzu Corporation) of a laser diffraction method. The pulverization method is not particularly limited, and examples thereof include a dry pulverizer such as a jet mill and a high-speed rotary mill, and a wet pulverizer such as an attritor, a sand grinder, and a ball mill.

  The pulverized raw material 20 is preferably agglomerated, and after cooling in the cooler 28, the raw material 20 is sorted by a particle size sorter 29 such as a vibration sieve and stored in the silo 30 as regenerated particles.

[Method for producing silica composite regenerated particles]
As a method for combining silica on the surface of the regenerated particles described above, for example, the method described in Japanese Patent No. 3907688 or Japanese Patent No. 4087431 can be used as appropriate. However, the following production method is preferable in that silica composite regenerated particles having more excellent opacity can be obtained.

  As a method for producing the silica composite regenerated particles, the regenerated particles obtained by the method for producing regenerated particles are added and dispersed in an alkali silicate aqueous solution to form a slurry, and the mineral is produced in a temperature range of 50 ° C. to 100 ° C. with stirring. A method of adding an acid is preferred. Among them, it is more preferable to carry out a silica composite reaction by adding a mineral acid in at least two stages. This manufacturing method will be described in detail below.

  In the method for producing silica composite regenerated particles, it is preferable to use regenerated particles having a volume average particle diameter of 1.0 μm or more and 10.0 μm or less. In addition, the said volume average particle diameter is the value which measured and averaged the particle diameter of the reproduction | regeneration filler by the laser analysis type particle size distribution measuring apparatus "SALD-2200 type" Shimadzu Corporation make. By making the volume average particle diameter of the regenerated particles used within the above range, the obtained silica composite regenerated particles have an appropriate particle diameter as a filler.

The alkali silicate aqueous solution used for the manufacturing method of the said silica composite reproduction | regeneration particle | grains is not specifically limited, For example, the sodium silicate solution (No. 3 water glass) etc. which can be obtained easily are mentioned. The concentration of the alkali silicate solution is preferably 3% by mass or more and 10% by mass or less as the silicic acid content (in terms of SiO ₂ ) in the aqueous solution. By setting the concentration of the alkali silicate solution in the above range, the white carbon of the silica can be prevented and the surface of the regenerated particles can be uniformly coated with silica.

  The slurry concentration in the case of preparing a slurry by adding and dispersing regenerated particles in an aqueous alkali silicate solution is preferably 8% by mass or more and 14% by mass or less. By adjusting the slurry concentration within the above range, the composition ratio of the regenerated particles and silica can be adjusted at the same time as controlling the particle diameter of the formed silica composite regenerated particles.

  Further, the solid content ratio of the alkali silicate aqueous solution to the regenerated particles is preferably 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the regenerated particles. By setting the solid content ratio of the alkali silicate aqueous solution to the regenerated particles in the above range, sufficient silica precipitation is obtained on the surface of the silica composite regenerated particles, and the porosity and opacity of the coated paper can be improved.

The temperature of the alkali silicate aqueous solution when adding the regenerated particles to the alkali silicate aqueous solution is not particularly limited. For example, the regenerated particles may be added after the liquid temperature of the alkali silicate aqueous solution is set to 50 ° C. or higher in advance. You may heat suitably after adding particle | grains. Among these, it is preferable to add the regenerated particles in a state where the alkali silicate aqueous solution has been heated to 50 ° C. or higher in advance because the fluidity is improved by the heating and the slurry is easily homogenized. As the heat source, a known heat source may be used as appropriate. For example, by blowing live steam (for example, 13 kg / cm ² , 120 ° C., etc.) in the factory, the heating time can be shortened and the energy efficiency can be improved. .

  Examples of the mineral acid used in the method for producing the silica composite regenerated particles include dilute sulfuric acid, dilute hydrochloric acid, dilute nitric acid and the like. Among them, dilute sulfuric acid is preferable because it is inexpensive and easy to handle. As the concentration of the mineral acid, for example, when dilute sulfuric acid is used, a concentration of 4N or more and 10N or less is preferable. By setting the concentration of dilute sulfuric acid within the above range, the composite reaction of silica proceeds without unevenness while maintaining a sufficient reaction rate. Further, since the silica is combined in a shorter time as the amount of the mineral acid added is larger, the amount added may be appropriately adjusted according to the target condition. However, since the regenerated particles used as the core material contain calcium, aluminum, and silica, care must be taken because excessive addition of mineral acid may cause alteration of the regenerated particles.

  As the method for adding the mineral acid, it may be added continuously, but it is desirable to add it in two or more stages.

  When the mineral acid is continuously added, it is preferable to set the addition amount so that the addition time of the mineral acid is 40 minutes or more even though the pH is lowered by 1.

  When the mineral acid is added in two or more stages, it is preferable to equalize the amount of mineral acid added in each stage so that a homogeneous silica composite is obtained. As the addition of the first stage, for example, the mineral acid may be added until the neutralization rate of the alkali silicate aqueous solution becomes 20% or more and 50% or less. By stopping the addition of the mineral acid for a minute or less and providing a holding state in the silica composite reaction, the silica can be uniformly combined on the surface of the regenerated particles. Subsequently, by further adding a mineral acid in the second stage, it is possible to further promote the formation of a composite layer of silica, and to combine the silica more uniformly on the surface of the regenerated particles.

  In the addition of the mineral acid in the first stage, it is preferable to set the addition amount of the mineral acid so that the time required for the addition of the mineral acid is 10 minutes or more and 45 minutes or less. In this case, it is preferable to set the time required for the addition of the mineral acid to 10 minutes or more and 120 minutes or less when the pH is lowered by 1. By setting the amount of mineral acid added in this way, silica can be uniformly combined on the surface of the regenerated particles.

  For example, the upper limit of the slurry liquid temperature is preferably 100 ° C. and more preferably 98 ° C. when the mineral acid is continuously added. On the other hand, the lower limit of the liquid temperature is preferably 50 ° C. Since the slurry liquid temperature affects the silica formation, crystal growth rate, and mechanical strength of the resulting silica composite regenerated particles, the silica is uniformly combined on the surface of the regenerated particles by setting the slurry liquid temperature within the above range. In addition, it is possible to obtain silica composite regenerated particles having sufficient strength. In addition, when the said slurry liquid temperature exceeds 100 degreeC, reaction will advance excessively, the form of a silica composite reproduction | regeneration particle | grain will become precise | minute, and care must be taken because the opacity as the silica composite reproduction | regeneration particle | grains obtained falls.

  The reaction temperature when adding the mineral acid in two or more stages is, for example, set the slurry liquid temperature at the time of the first stage mineral acid addition to 50 ° C. or more and 75 ° C. or less, and after the second stage. It is preferable to set the slurry liquid temperature at the time of addition of the mineral acid at least 10 ° C. higher than at the time of the first stage addition. More specifically, for example, the slurry liquid temperature at the time of the first stage mineral acid addition is set to 50 ° C. or higher and 75 ° C. or lower, and the slurry liquid temperature at the time of the subsequent second or subsequent mineral acid addition is set to 70 ° C. The temperature is preferably set to 100 ° C. or lower and the slurry liquid temperature is preferably set to 90 ° C. or higher and 98 ° C. or lower in the final stage of the reaction. Thus, by making the slurry liquid temperature at the time of mineral acid addition into the said range, the silica composite reproduction | regeneration particle | grains which the silica combined with the reproduction | regeneration particle more homogeneously can be obtained.

  In the method for producing silica composite regenerated particles, the upper limit of the pH of the final reaction solution is preferably 11, more preferably 10, and still more preferably 9. On the other hand, the lower limit of the pH is preferably 8, more preferably 8.3, and even more preferably 8.5. Thus, by setting the pH of the final reaction solution within the above range, the calcium component contained in the regenerated particles can be prevented from changing to calcium hydroxide, the shape is uniform, the particle size is appropriate, and it is sufficiently opaque. A silica composite regenerated particle having a property improving effect is obtained.

  The volume average particle diameter of the silica composite regenerated particles obtained by the above production method depends on the particle diameter of the regenerated particles combined with silica, but the upper limit of the volume average particle diameter is preferably 10 μm, more preferably 7 μm. On the other hand, the lower limit is preferably 1.7 μm, more preferably 3 μm. Thus, by making the volume average particle diameter of the silica composite regenerated particles in the above range, the effect of silica composite can be fully expressed, excellent in oil absorption and opacity, and densely filled voids between pulp fibers Silica composite regenerated particles that can be obtained can be obtained.

  In the above production method, a stirring means such as, for example, reversing the stirring blades in the stirring tank to generate turbulent flow or providing a baffle plate in the stirring tank is used as appropriate so that the reaction proceeds uniformly throughout the slurry. It is preferable to adopt.

  By the method for producing the silica composite regenerated particles, silica sol particles having a particle diameter of 10 nm or more and 20 nm or less measured by a scanning electron microscope are formed on the surface of the regenerated particles. The particle size of the silica sol particles can be controlled by the stirring conditions during the reaction or the addition conditions of the mineral acid.

  The silica composite regenerated particles obtained by the above production method preferably have a pore radius of 10,000 angstroms or less, and the silica composite regenerated particles have a pore volume of mercury intrusion porosimeter (“PASCAL 140 / 240 ") is preferably 1.5 cc / g, more preferably 1.45 cc / g, and even more preferably 1.35 cc / g as the upper limit of the pore volume in the region of 10,000 angstroms or less. On the other hand, the lower limit of the pore volume is preferably 0.5 cc / g, more preferably 0.68 cc / g, and even more preferably 0.70 cc / g. Thus, by making pore volume into the said range, the silica composite reproduction | regeneration particle | grains which have sufficient oil absorption amount and opacity can be obtained.

Since the regenerated particles are indeterminate, the yield is high, and thus coated paper having high wrinkle resistance and excellent opacity and printing gloss can be obtained. As a result, the coated paper containing the regenerated particles obtained by the production method in the base paper is less likely to generate wrinkles even when high-speed offset rotary printing at a printing speed of 1000 rpm or more is performed.

It is preferable to add an internal sizing agent to the raw material pulp in addition to the filler described above. When recycled particles are contained in the base paper as a filler, the ink absorbability of the base paper is likely to be high, and the printing ink is easily absorbed to reduce the printing gloss. Therefore, it is preferable to reduce the ink absorptivity of the base paper and improve the printing gloss by adding an internal sizing agent.

In the present embodiment, in addition to the internal sizing agent, the raw material pulp includes, for example, a paper strength improver, a paper thickness improver, and a yield improver (water-soluble polymers such as various synthetic polymers and starches). In addition, various additives such as these fixing agents that are usually blended into the base paper of the coated paper can be internally added by appropriately adjusting the kind and blending amount thereof.

In addition, it is preferable to adjust the jet wire ratio in a paper machine because it can prevent wrinkles. During printing, the paper is printed while being pulled in the papermaking direction, so that creases caused by water evaporation in the base paper are generally less likely to occur in the papermaking direction and more likely in the width direction. For this reason, by making the jet wire ratio 1 or more (the speed of the paper jet is faster than the wire speed), the fibers can be easily oriented in the width direction, and the tensile strength in the width direction can be improved. It is easier to reduce wrinkles.

After making the papermaking raw material as described above in the wire part and then supplying it to the press part and the pre-dryer part to produce the base paper, and then coating the base paper with the coating liquid described later in the coater part It can be used for an after dryer part, a calendar part, a reel part, a winder part and the like to obtain a desired coated paper.

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 40 to 100 g / m ^2. Usually, it is preferable to adjust so that it may be about 20-80 g / m < ² >.

<Clear coating layer>
The base paper may be provided with a clear coating layer mainly composed of a water-soluble polymer before providing a pigment coating layer described later.

There is no restriction | limiting in particular in the water-soluble polymer used for a clear coating layer, Generally what can be used for a papermaking use can be used. Specifically, starch such as oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch and raw starch or derivatives thereof, synthetic polymers such as polyvinyl alcohol, and the like can be used. Among these, use of oxidized starch is preferable because it can sufficiently improve the surface strength while preventing the latex from sinking into the base paper, and can prevent paper breakage during printing.

In general, oxidized starches include those that oxidize and decompose starch with oxidizing agents such as ammonium persulfate, sodium hypochlorite, and potassium hydrogen persulfate, and those that oxidize by acid hydrolysis, among which potassium hydrogen persulfate. It is preferable to use oxidized starch obtained by oxidation with, because it is easier to prevent crumpling. In the oxidized starch obtained by using an oxidizing agent other than potassium hydrogen persulfate, latex, particularly latex having a butadiene component described later of 50% by mass or more, and further to a latex base paper having an average particle size of 115 to 160 nm. It tends to be difficult to prevent subsidence, and the generation of elbows is harder to prevent than potassium hydrogen persulfate.

Clear coating layer is preferably provided so as to be per side 0.2 to 2.0 g / ^{m 2,} further is more preferably provided so as to be per side 0.5 to 1.0 g / ^{m 2.} If it is less than 0.2 g / m ² , it is difficult to sufficiently obtain the sealing effect, it is difficult to prevent the latex from penetrating from the pigment coating layer to the base paper, and the surface strength is liable to be lowered. Exceeding 2.0 g / m ² is not preferable because the amount of coating becomes too large, and moisture in the base paper is difficult to evaporate during drying after printing, and thus wrinkles are likely to occur.

The clear 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. The film transfer method is a method in which the coating material is transferred to paper after coating the coating material on the roll.For example, compared to a method in which a pound of coating liquid is formed and applied, such as a two-roll size press, This is preferable because pressing of the coating liquid onto the surface of the base paper is reduced, and a clear coating layer having a higher bulkiness and a higher porosity can be formed. In addition, since the film transfer method can apply a coating layer with a constant film thickness to the surface of the base paper, a uniform coating layer can be obtained and a clear coating layer that can transmit water vapor without unevenness can be formed. It is preferable because it is difficult to generate bulges.

(Pre-calendar part (flattening process))
The base paper provided with the base paper or the clear coating layer is preferably subjected to a flattening treatment with a pre-calender before the pigment coating. By performing the flattening treatment, unevenness in the smoothness of the base paper can be reduced, the thickness of the pigment coating layer can be made uniform, the water vapor from the base paper can be easily evaporated, and local wrinkles can be prevented easily. .

<Pigment coating layer>
The base paper or the base paper provided with the clear coating layer is provided with a pigment coating layer mainly composed of a pigment and an adhesive.
(Pigment)
As the pigment used in the coating layer, those conventionally used as a pigment in general papermaking applications can be used. For example, calcium carbonate, kaolin clay, calcined kaolin, deramikaolin, titanium dioxide, zinc oxide, silicon oxide Amorphous silica, magnesium carbonate, barium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide and the like can be mentioned, and one or more kinds can be used in combination as required. Further, the regenerated particles described above may be used.

The pigment of the coating layer is such that particles having a particle diameter of 1.0 μm or more are 5% by mass or less of the entire pigment. When particles having a particle size of 1.0 μm or more, for example, delaminated clay or large particle size clay exceeds 5% of the total pigment, the covering property is improved and the printing gloss is improved, but the glossiness of blank paper is likely to be lowered. It is necessary to increase the calendar pressure in the flattening process, and the coated paper is inferior in rigidity. A coated paper having inferior rigidity tends to shrink due to moisture absorption or evaporation, and there is a problem that wrinkles are generated in printing. On the contrary, when the particle diameter is 1.0 μm or more and 5% by mass or less of the whole pigment, it is easy to pack the pigment densely, and there are too few voids inside the coating layer, and the moisture in the base paper is particularly difficult to evaporate. , It will be difficult to prevent the occurrence of wrinkles. For this reason, in the present invention, not only the particles having a particle diameter of 1.0 μm or more as the pigment of the coating layer are set to 5% or less of the whole particles, but also contains 50% by mass or more of the butadiene component as an adhesive as described later. By adding 4 to 7 parts by mass of the adhesive to be used with respect to 100 parts by mass of the pigment, a coated paper that can sufficiently prevent wrinkles can be obtained. That is, by using an adhesive containing a high adhesive butadiene component, the amount of the adhesive can be reduced to a minimum of 4 to 7 parts by mass with respect to the pigment. It is possible to minimize a decrease in water vapor permeability resulting from the film formation of the adhesive, and it is possible to prevent a decrease in wrinkle resistance.

In addition, the particle diameter of this invention was measured as follows. The pigment particles on the coated paper surface were photographed using a scanning electron microscope (model number: S-2150, manufactured by Hitachi, Ltd.). Since the pigment particle is not a perfect circle, the diameter of the smallest circle (the smallest circle circumscribing the particle) that can enclose the entire particle is taken as the particle diameter.

(adhesive)
As an adhesive for the coating layer, it is necessary to use 4 to 7 parts by mass of a styrene-butadiene latex having a butadiene component of 50% by mass or more based on 100 parts by mass of the pigment.

When the butadiene content in the styrene-butadiene latex is less than 50% by mass, the adhesive strength is likely to be reduced, and the latex in the coating solution is easily absorbed by the base paper, resulting in a lower surface strength. There is an easy problem. In addition, since the strength of the coating layer itself is also reduced, it is difficult to prevent creases, which is not preferable.

When the content of latex is less than 4 parts by mass with respect to 100 parts by mass of the pigment, there is a problem that the amount of latex in the coating layer becomes too small, and the surface strength and wrinkle resistance of the coating layer are lowered. If the latex exceeds 7 parts by mass, the latex will form a film in the coating layer, making it difficult for water vapor to permeate, and sufficient wrinkle resistance cannot be exhibited. In addition, since a large amount of latex is contained in the coating layer, there is a problem that the glossiness of the white paper and the printing glossiness derived from the coating pigment are lowered. In the present invention, since the latex having a butadiene component of 50% by mass or less is suppressed to a low amount of 7 parts or less, the latex does not easily permeate the base paper and easily stays in the coating layer. In addition, it is possible to obtain a coated paper which is excellent in surface strength and coating layer strength and does not generate wrinkles.

As such a latex, the coating layer becomes soft especially when the glass transition temperature is −20 to 10 ° C., so that water vapor easily passes through the coating layer and can effectively prevent generation of wrinkles. More preferable. Furthermore, when the average particle size of the latex is as large as 115 to 160 nm, the voids in the coating layer become large, so that water vapor is more easily transmitted through the coating layer. In addition, when the gel content is as low as 70 to 95% by mass, a coating layer having a larger void can be obtained, so that steam is particularly easy to permeate the coating layer, and in particular, the effect of preventing wrinkles is enhanced. As described above, particles having a particle diameter of 1.0 μm or more as a pigment are 5% by mass or less of the total pigment, and the coating layer has a styrene-butadiene having a butadiene component as an adhesive of 50% by mass or more. By containing the latex in a low amount of 4 to 7 parts by mass with respect to 100 parts by mass of the pigment, a coated paper that can easily prevent generation of wrinkles can be obtained.

Furthermore, as in the present invention, when using a base paper containing particles having a high porosity such as regenerated particles obtained in the production process, the latex having the above average particle diameter, glass transition temperature and gel content, Use in combination is preferable because generation of elbows can be further prevented. In particular, as in the present invention, when printing is performed using a high-speed rotary offset printing machine having a printing speed of 1,000 rpm or higher, the paper surface temperature tends to be as high as 110 ° C. or higher. Thus, generation of wrinkles can be particularly effectively prevented.

As the adhesive, in addition to the latex having a butadiene content of 50% by mass or more, an adhesive that can be conventionally 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 non-soluble 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.

In addition to pigments and adhesives, the coating liquid used in this 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 auxiliaries 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 of preparing the coating liquid, and the mixing ratio of pigments, adhesives, dust inhibitors, and various auxiliary agents as necessary is adjusted as appropriate to obtain a uniform composition at an appropriate temperature. As such, stirring and mixing may be performed. Moreover, the solid content concentration of the 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 pigment coating layer is dried with a drying device after coating. Various types of drying apparatuses are known, but a hot air dryer or an infrared drying apparatus is generally used. In the present invention, it is preferable to dry using at least one infrared drying apparatus immediately after coating. Drying with infrared rays is uniformly heated from the inside of the coating layer, so that the coating liquid does not flow easily, especially because it is easy to prevent the latex from sinking into the base paper. The coated layer can be formed, which is preferable because it is easy to prevent the generation of local wrinkles. On the other hand, hot-air drying is not preferable because moisture is rapidly evaporated from the surface of the pigment coating layer, so that the coating liquid tends to flow (particularly migration) inside the coating layer and latex tends to be unevenly distributed.

Infrared drying is preferably used for initial drying performed immediately after coating, and is preferably installed before the hot air dryer group. It is preferable to perform infrared drying immediately after coating because it is particularly easy to prevent the flow of coating liquid (particularly migration) and absorption of latex into the base paper, and to further prevent uneven distribution of latex.

The infrared output is not particularly limited. However, in order to prevent the uneven distribution of latex as described above, it is preferable to use an infrared drying apparatus having a larger infrared output and a higher drying ability. For example, it is preferable to use an infrared drying apparatus having a coating speed of 1,500 m / min and a coating width of 200 kWh / m or more. If it is less than 200 kWh / m, the flow of the latex may not be sufficiently suppressed, and it is not only difficult to prevent the generation of wrinkles, but also preferred because the surface strength tends to decrease due to the uneven distribution of latex in the coating layer. Absent.

As the infrared ray to be used, any wavelength of near infrared, middle infrared, and far infrared can be used, and any wavelength can be used without particular limitation as long as the wavelength is 0.75 to 10 μm.

As described above, the clear coating layer contains oxidized starch, particularly oxidized starch obtained by oxidation with potassium hydrogen persulfate, and a latex having a large average particle size of 115 to 160 nm is used as the latex of the pigment coating layer. In addition, it is preferable to use an infrared drying apparatus having a large output of 200 kWh / m or more per coating width as initial drying, because it is easy to suppress the absorption of latex into the base paper, and particularly easy to prevent generation of wrinkles.

Further, on a base paper containing regenerated particles obtained through a drying step and at least three heat treatment steps, pigment particles having a particle diameter of 2 μm or more are 5% or less of the total pigment, and 50% butadiene component is used as an adhesive. By providing a pigment coating layer containing 4 to 7 parts by mass of styrene-butadiene latex of 100% by mass or more based on 100% by mass, both the porosity of the base paper and the porosity of the coating layer can be improved, and Since it is possible to reduce the non-uniformity in the porosity of the base paper due to the hard substance and the decrease in water vapor permeability due to the latex, even in an offset rotary printing press where the printing speed is as high as 1,000 rpm or more, In particular, it is preferable because it is easy to prevent the generation of local wrinkles.

Furthermore, when a clear coating layer containing oxidized starch, particularly oxidized starch oxidized with potassium hydrogen persulfate is provided on the base paper, the styrene-butadiene latex having a butadiene component of 50% by mass or more penetrates into the base paper. Even if the latex is as low as 4 to 7 parts by mass with respect to 100 parts by mass of the pigment, not only can the pigment be sufficiently adhered, but also the decrease in water vapor permeability caused by the film formation of the latex is minimized. Since it can be suppressed to the limit, generation of elbows is particularly easily prevented, which is preferable.

As described above, 0.2 to 2 per side on a base paper containing 2 to 10% by weight, preferably 3 to 9% by weight, of regenerated particles obtained through a drying step and at least three heat treatment steps as ash in the paper. Provided with a clear coating layer containing oxidized starch, particularly oxidized starch oxidized with potassium hydrogen persulfate so as to be 0.5 to 1.0 g / m ² per side, preferably 0.5 to 1.0 g / m ² , and further having a particle diameter of 2 μm or more The styrene-butadiene latex having a butadiene component content of 50% by mass or more and an average particle size of 115 to 160 nm as an adhesive is 4 to 7% by mass with respect to 100 parts by mass of the pigment. By using an infrared drying apparatus having a large output of 200 kWh / m or more per coating width as the initial drying, the porosity of the base paper and the porosity of the coating layer are provided. In addition, the uneven distribution of hard substances and latex can be suppressed, so that the generation of folds, especially local folds, can be sufficiently prevented even in a rotary offset printing press with a high printing speed of 1,000 rpm or higher. This is preferable because a coated paper that can be easily applied is obtained.

For the purpose of further improving the printability, the coating layer formed as described above 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 surface of the paper with a wide surface at a high temperature so that it can be flattened 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. When a multi-nip calender that can adjust the linear pressure as appropriate is used, it is possible to minimize a decrease in porosity in the coating layer 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 the glossiness of blank paper is easy to improve, the linear pressure required to obtain the desired coated paper is low, and the coated paper is Since it is difficult to be crushed, it becomes a coated paper in which the generation of wrinkles is further prevented.

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. However, if the coated paper is crushed too much, the rigidity is lost and it is difficult to prevent generation of wrinkles. Therefore, the linear pressure is more preferably suppressed to 100 to 250 kN / m.

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 Papermaking, clear coating, pigment coating, drying and flattening treatment were carried out at the types and ratios shown in Table 1 to obtain coated paper for printing. The pigments, raw materials and chemicals used are as follows.
<Manufacture of regenerated particles>
Using paper sludge derived from the waste paper treatment process for producing waste paper pulp as the main raw material, after dehydrating the raw material so that the moisture content after the dehydration process is 35% by mass, the ratio of the particle diameter of 50 mm or more is 50% by mass The raw material is dissolved so that the average particle diameter is 3 mm, and air drying is performed using a drying apparatus (manufactured by Shin Nihonkai Heavy Industries, Ltd., “Kudakera”), followed by the first heat treatment step (furnace Body temperature 280 ° C., furnace body oxygen concentration 12% by volume), second heat treatment step (furnace body temperature 380 ° C., furnace body oxygen concentration 12% by volume) and third heat treatment step (supply hot air temperature 700 ° C., furnace After passing through the body oxygen concentration of 12% by volume, regenerated particles were obtained by wet pulverization.

  The external heat kiln furnace used in the first and second heat treatment steps employs an external thermoelectric kiln furnace having a parallel lifter and a helical lifter inside, and in the third heat treatment step, the main body The internal heat kiln furnace that rotates horizontally around the central axis is used, and a parallel flow system is adopted in which raw materials such as deinking floss are supplied from a raw material supply port at one end of the internal heat kiln furnace and hot air is blown.

  The obtained regenerated particles were wet pulverized using a ceramic ball mill, and the volume average particle size was adjusted to 1.0 μm.

Fillers, starches, pigments and latex other than regenerated particles are as follows.
(Filler)
・ Calcium carbonate (light, product number: TP-121-6S, manufactured by Okutama Kogyo Co., Ltd.)
(Clear coating layer)
A: Oxidized starch oxidized with potassium hydrogen persulfate B: Oxidized starch oxidized with sodium hypochlorite C: Oxidized starch oxidized with ammonium persulfate Raw starch (Sanwa Corn Starch, Sanwa Starch Kogyo Co., Ltd.) ) Was prepared by oxidizing with the above oxidizing agent.
(Pigment)
・ Heavy calcium carbonate (Product No .: Hydrocurve 90, manufactured by Bihoku Powder Chemical Co., Ltd., average particle size 1.3 μm)
HC clay (product number: CENTURY-HC, manufactured by Mitsubishi Corporation, average particle size (d50) 2.7 μm)
-Fine clay (product number: Amazon Plus, manufactured by CADAM, average particle size (d50) 0.3 μm)
(adhesive)
D: Styrene-butadiene copolymer latex (product number: PA9902, manufactured by Nippon A & L, average particle size: 115 nm, butadiene 53 mass%).
E: Styrene-butadiene copolymer latex (product number: G-1377, manufactured by Asahi Kasei Corporation, average particle size: 160 nm, butadiene 57 mass%).
F: Styrene-butadiene copolymer latex (product number: T-2730P, manufactured by JSR Corporation, average particle size: 110 nm, butadiene 37% by mass).
G: Styrene-butadiene copolymer latex (product number: XY-2, manufactured by Nippon A & L, average particle size: 130 nm, butadiene 43% by mass).
H: Styrene-butadiene copolymer latex (product number: PA-4098, manufactured by Nippon A & L, average particle size: 95 nm, butadiene 48 mass%).
-PVA: Polyvinyl alcohol (product number: PVA110, manufactured by Kuraray Co., Ltd.).

(Manufacturing procedure)
NBKP, LBKP, and DIP derived from magazine waste paper are mixed at a ratio of 20:70:10 as raw material pulp, and each type of filler shown in Table 1 is shown in solid content with respect to this pulp (absolute dry amount). In addition, an internal sizing agent (product number: AK-720H, manufactured by Harima Chemical Co., Ltd.) 0.05% by mass, cationized starch (product number: amylofax T-2600, Abebe) A pulp slurry was obtained by adding 1.0% by mass of Japan Co., Ltd.) and 0.02% by mass of a yield improver (product number: NP442, manufactured by Nissan Eka Chemicals Co., Ltd.).

The pulp slurry is paper-made at a jet wire ratio (J / W) described in Table 1, and then subjected to a press part and a pre-dryer part to produce a base paper, and then in the undercoater part, oxidized starch or A clear coating layer containing PVA is provided by coating so as to have the amount shown in Table 1 per side, and in the top coater part, the pigments shown in Table 1 and 100 parts by mass of the pigment are listed in Table 1. Coating chemicals containing various types of adhesives in the amounts shown in Table 1 were applied so as to be 7 g / m ² per side to produce a coated paper for printing having a basis weight of 64 g / m ² . The pigment was prepared by mixing clay shown in Table 1 and heavy calcium carbonate not shown in Table 1 to 100 parts by mass.

In the after-dryer part, using an infrared drying device (IRT-SYSTEM 18kW module, 2 stages, manufactured by Fuji Electric Systec Co., Ltd.) at a drying speed of 1500 m / min with the output shown in Table 1, further drying with hot air to dry the coated paper It was. Further, the calendar part was flattened by applying a calendar at the flattening conditions (nip pressure) shown in Table 1 and a speed of 1000 m / min.

In addition to the above, the manufacturing system may use an off-machine coater in which the paper machine and the coater part are separated, or a system including an off-machine calendar in which the paper machine and the soft calendar are separated.

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 super calendar was used.

About the obtained coated paper, blank paper glossiness, printing glossiness, surface strength, and wrinkles generated during rotary printing were evaluated by the following methods. The results are shown in Table 1.

The ratio of pigment particles having a particle diameter of 2 μm or more was determined as follows. The coated paper was cut out to A4 size, and a sample of 5 mm square was cut out at a point of Acm from the upper side to the lower side and Acm from the left side, with the short side of the paper as the upper side. Here, A is an integer of 1 to 20, and a total of 20 samples were collected. The surface of the cut out sample was photographed at a magnification of 12000 using a scanning electron microscope (model number: S-2150, manufactured by Hitachi, Ltd.). The particle diameter was measured for the clay closest to the point Bcm from the upper side to the lower side of the photograph and Bcm from the left side, and the entire particle being photographed. Here, B is an integer of 1 to 5, and the particle diameter of five clay particles was determined from one sample, and the particle diameter was determined for a total of 100 clay particles. When a plurality of types of pigments such as regenerated particles, calcium carbonate, kaolin clay, and the like are used in combination, it is possible to determine which particle is which pigment. The regenerated particles are aggregated particles composed of calcium, silicon and aluminum derived from deinked floss, heavy calcium carbonate is amorphous spherical particles, light calcium carbonate is spindle-shaped particles, and kaolin clay is plate-shaped. Particles. The shape can be sufficiently discriminated at a magnification of 12000 times.

(A) Blank paper glossiness JIS-P-8142: 2005 was measured for unprinted coated paper according to the method described in “Paper and paperboard—Measurement method of 75 ° specular gloss”. If the blank paper glossiness is 40% or more, the blank paper glossiness is good and can be used practically. If the blank paper glossiness is 50% or more, the blank paper glossiness is excellent and the coated paper is excellent in appearance. If the glossiness of the blank paper is below 40%, the glossiness of the blank paper is inferior, and the coated paper cannot be actually used.

・ Preparation of printing sample Using offset printing machine (model number: LITHO PIAMAXBT2-1000, manufactured by Mitsubishi Heavy Industries, Ltd.), color ink (product number: ADVAN, manufactured by Dainippon Ink & Chemicals, Inc.) Four-color printing was printed with 5000 copies at a speed of 1,000 rpm. The paper surface temperature was set to 115 ° C.

(B) Print Glossiness JIS-P-8142: 2005 was measured for the printed sample printed as described above according to the method described in “Paper and paperboard—Measurement method of 75 ° specular gloss”. If the printing glossiness is 70% or more, the printing glossiness is good and can be used practically. If the printing glossiness is 76% or more, the printing glossiness is excellent and the coated paper is excellent in appearance. If the printing glossiness is less than 70%, the printing glossiness is inferior, and the coated paper cannot be actually used.

(C) Surface strength The above printed sample was visually confirmed using a magnifying glass (10 times), and the degree of occurrence of unprinted portions (white spots) was evaluated as follows. ○: Coating with no appearance of white spots and excellent appearance It is craft paper.
Δ: Coated paper with good appearance, although some white spots have occurred, and can be used in practice.
X: A white paper is generated, and the coated paper is poor in appearance, and cannot be actually used.

(D) The degree of generation of creases in the crease print sample was visually evaluated according to the following criteria.
○: There is no generation of wrinkles, and actual use is possible.
(Triangle | delta): Although a wrinkle generate | occur | produced a little, it can actually be used.
X: Hijiwa was generated, the appearance was inferior, and practical use was impossible.

  In any of the coated papers of Examples, the pigment particles having a particle diameter of 2 μm or more are 5% or less of the total pigment as the pigment in the coating layer, and the coating layer contains 50 butadiene component as an adhesive. Since 4-7 parts by mass of styrene-butadiene latex of 100% by mass or more is contained with respect to 100 parts by mass of the pigment, the coated paper has high white paper gloss, printing gloss and surface strength, and is less likely to cause wrinkles. It is.

  On the other hand, in the coated paper of the comparative example, as the pigment in the coating layer, pigment particles having a particle diameter of 2 μm or more are not 5% or less of the total pigment, or the coating layer has butadiene as an adhesive. Since the component is not a styrene-butadiene latex of 50% by mass or more or does not contain 4-7 parts by mass of the latex with respect to 100 parts by mass of the pigment, one or more of blank paper glossiness, printing glossiness, surface strength The coated paper is inferior and cannot prevent the generation of wrinkles.

The coated paper of the present invention can be suitably used as a printing coated paper used in offset printing.

It is a typical schematic diagram of the production facility of regenerated particles used for one embodiment of the coated paper of the present invention. It is a schematic schematic diagram of the 3rd heat treatment furnace of the manufacturing apparatus of the reproduction | regeneration particle | grains of FIG. (A) is a typical longitudinal cross-sectional view of a 3rd heat treatment furnace, (b) is a typical expanded view of the inner surface of a 3rd heat treatment furnace.

DESCRIPTION OF SYMBOLS 1 ... Pre tank 2 ... Receiving chest 3 ... Compounding chest 4 ... 1st fan pump 5 ... Machine chest 6 ... 2nd fan pump 7 ... Seed box 8 ... 3rd fan pump 9 ... Cleaner 10 ... 4th fan pump 11 ... Screen 12 ... paper machine 20 ... raw material 21 ... storage tank 22 ... drying device 23 ... charging machine 24 ... first heat treatment furnace (external heat kiln furnace)
24A ... supply port 24B ... discharge port 24C ... external heat jacket 25 ... second heat treatment furnace (external heat kiln furnace)
25A ... supply port 25B ... discharge port 25C ... external heat jacket 26 ... charging machine 27 ... third heat treatment furnace (internal heat kiln furnace)
27A ... Supply port 27B ... Discharge port 28 ... Cooler 29 ... Particle size sorter 30 ... Silo 31 ... Recombustion chamber 32 ... Precooler 33 ... Heat exchanger 34 ... Attraction fan 35 ... Chimney 36-39 ... Hot air generator 36A 39A ... Burner 50 ... Helical lifter 51 ... Parallel lifter 52 ... Outer casing 53 ... Fireproof wall 54 ... Mounting bracket 55 ... Mounting bracket

Claims (3)

A coated paper having a pigment coating layer mainly composed of a pigment and an adhesive on the base paper and the base paper,
The pigment has a particle diameter of 2 μm or more and 5% or less of all pigment particles,
Coated paper, wherein the adhesive contains at least a styrene-butadiene latex having a butadiene component of 50% by mass or more, and the ratio of the adhesive to 100 parts by mass of the pigment is 4 to 7 parts by mass.   The coated paper according to claim 1, wherein the base paper contains regenerated particles obtained from papermaking sludge as a main raw material and subjected to a dehydration step, a drying step, a heat treatment step of at least three steps and a pulverization step. paper. A clear coating layer mainly composed of starch is provided between the base paper and the pigment coating layer, and the starch is an oxidized starch obtained by oxidation with potassium hydrogen persulfate. The coated paper according to claim 1 or 2.

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