JP5688228B2 - Newspaper production method and newsprint - Google Patents

Description

  The present invention relates to a newsprint paper manufacturing method and newsprint paper obtained by this manufacturing method.

  Conventionally, in the paper industry, virgin pulp having thick fibers such as mechanical pulp is added to raw pulp in order to improve the opacity and strength of newsprint. However, in recent years when recycling of resources is required in consideration of environmental problems, it is desired to actively reuse waste paper pulp obtained by collecting newspapers and magazines that have been distributed once. Use of a large amount of virgin pulp is contrary to the recyclability described above. On the other hand, since recycled paper pulp is repeatedly reused with the widespread use of recycled paper obtained by recycling recycled paper, it is inevitable that the recycled paper pulp fiber breaks during the recycling process, and the recycled paper pulp contains a lot of such fine fibers. The strength of the recycled paper using the inevitably decreases. Such reuse of waste paper pulp, while satisfying the above-mentioned recycling properties, causes a decrease in printing properties such as paper strength, opacity, oil absorption, etc. When used on newsprint, Omission and concealment properties are reduced, and inconveniences such as fading of the printing surface, omission of halftone dots, and appearance are likely to occur.

  In addition, as a countermeasure for opacity associated with the weight reduction of newsprint, attempts have been made to increase the amount of filler or ash. As such a filler, for example, white carbon or calcium carbonate is generally used. However, a simple increase in these fillers has a limit in improving opacity, and at the same time, the strength of the resulting newspaper. This causes inconveniences such as a decrease and an increase in paper dust.

  Therefore, in order to improve these inconveniences, the filler internal addition method has been improved. For example, Japanese Patent No. 2960001 proposes a method for producing a filler-added paper in which white carbon is used in combination with talc, clay, or kaolin to add a filler. The white carbon used in this production method is a fine one obtained by neutralizing sodium silicate with sulfuric acid, and its particle size is smaller than that of conventional white carbon particles. Can be improved.

  As another technique, for example, in Japanese Patent Application Laid-Open No. 2002-201590, white carbon and calcium carbonate are used as main fillers, and the ratio of ash in atomic absorption analysis is 9: 1 to 5: 5. A method for producing newsprint containing the main filler is proposed. This production method makes it possible to produce newsprint at a low cost by using cheap calcium carbonate and making raw pulp in a pH 6 to 8 range in which the yield of white carbon is good.

  However, the newsprint obtained by the manufacturing method as described above has a poor filler yield, and there are many gaps between the filler and the pulp fibers, and light passes through these gaps, so opacity, whiteness, etc. The printing characteristics are not enough. In addition, the newsprint obtained by the above manufacturing method has weak adhesiveness between the pulp fibers and the filler is likely to fall off from the paper, so that paper dust accumulates in the machine system, and periodic machine cleaning work is not possible. There is an inconvenience that it becomes necessary and the operation efficiency decreases.

Japanese Patent No. 2960001 JP 2002-201590 A

  The present invention has been made in view of these inconveniences, and improves the yield of the filler by increasing the filler fixing property between the pulp fibers, thereby reducing the production cost, opacity, whiteness, It is an object of the present invention to provide a newsprint paper manufacturing method and a newsprint paper obtained by this manufacturing method in which the printing efficiency such as oil absorption is improved and the machine operation efficiency of the machine is improved by reducing paper dust fall.

  The invention made to solve the above problems is a newsprint production method comprising a raw slurry preparation step and a paper making step of making a newsprint using the raw slurry obtained in the raw slurry preparation step, The raw material slurry preparation step includes (1) a filler addition step of adding a filler to a pulp slurry containing raw material pulp, and (2) a flocculant addition step of adding a flocculant to the pulp slurry after the filler addition step. And the filler contains regenerated particles mainly made of paper sludge. In the flocculant addition step, the flocculant (A) has a smaller cation charge density than the flocculant (A) and has a weight average molecular weight. The flocculant (B) having a large size is added in this order.

  In the flocculant addition step after the filler addition step, the production method comprises the flocculant (A) and the flocculant (B) having a smaller cation charge density and a larger weight average molecular weight than the flocculant (A). By adding in this order, the filler and fine pulp fibers can be effectively aggregated. Further, the production cost can be reduced by improving the yield of the filler and fine pulp fibers. Furthermore, by improving these yields, it is possible to reduce paper dust fall, improve the operation efficiency of the machine, and improve printing characteristics such as opacity and oil absorption of the resulting newspaper. .

  In the production method, the regenerated particles may be obtained through a drying step and at least three heat treatment steps. The regenerated particles obtained by such a method can be produced stably, are extremely hard, such as gehlenite and anorthite, have low oil absorption, have a low content of substances that do not contribute to improvement in opacity, and are particularly opaque. Since it is excellent, the opacity and oil absorption of the resulting newsprint can be increased, and newsprint with excellent printing characteristics can be obtained.

  The regenerated particles preferably include two types of regenerated particles having different volume average particle diameters. By using such regenerated particles, it is possible to obtain newspapers in which voids between pulp fibers and irregularities on the paper surface are filled more precisely, and opacity and oil absorption are further improved and printing properties are excellent. Further, the gap between the pulp fibers is filled without gaps by two kinds of regenerated particles having different volume average particle diameters, whereby the filling structure is strengthened, the regenerative particles adherence is improved, and paper dust fall is reduced. In addition, the reduction of paper dust can reduce the contamination in the machine system in the paper making process, and the number of cleanings can be reduced, thereby improving the operating efficiency of the machine.

  The raw material pulp used in the production method preferably includes at least used paper pulp, and a coagulant is preferably added to the used paper pulp in advance. Thus, by adding a coagulant to waste paper pulp in advance, extremely fine fillers and pulp fibers derived from waste paper pulp form flocs more effectively, and yield is further improved.

  The newsprint obtained by the manufacturing method has higher opacity and whiteness and has excellent printing characteristics.

  The manufacturing method can reduce the manufacturing cost by improving the yield of the filler, and can improve the printing characteristics such as opacity and whiteness of the resulting newspaper. Moreover, since the said manufacturing method has few paper dust omission, the frequency | count of cleaning of a machine reduces and it can improve the operating efficiency of a machine. As a result, the manufacturing method can be suitably used as a method for manufacturing newsprint used for high-speed offset rotary printing. Moreover, the newsprint obtained by the manufacturing method has high opacity and whiteness, and has excellent printing characteristics.

It is a typical schematic diagram which shows the apparatus used for one Embodiment of the manufacturing method of the newsprint of this invention. It is a typical schematic diagram of the production facility of the regenerated particle used for one embodiment of the manufacturing method of the newsprint of the present invention. (A) And (b) is a typical longitudinal cross-sectional view and schematic expansion | deployment figure of an inner surface of the 3rd heat treatment furnace used for the manufacturing apparatus of the reproduction | regeneration particle | grains of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

  The manufacturing method of the newsprint of this invention has the raw material slurry preparation process which prepares the raw material slurry containing a pulp and a filler, and the papermaking process which makes this raw material slurry into paper. Further, the apparatus shown in FIG. 1 used in this newsprint manufacturing method includes a receiving chest 1, a blending chest 2, a first flow pump 3, a first machine chest 4, a second flow pump 5, and a second machine chest 6. The seed box feed pump 7, the seed box 8, the first fan pump 9, the cleaner 10, the second fan pump 11, the screen 12, and the paper machine 13 are provided in this order. The pulp as the raw material is put into the blending chest 2 and various additives are added as necessary. Thereafter, the pulp is sent to the first machine chest 4 by the first flow pump 3, and the second flow pump 5 makes the second flow. 2 sent to the machine chest 6, sent to the seed box 8 by the seed box feed pump 7, sent to the cleaner 10 by the first fan pump 9 to remove foreign matter, and then sent to the screen 12 by the second fan pump 11. Thereafter, paper is made by the paper machine 13. Thus, the raw material slurry preparation process is performed by the receiving chest 1 to the screen 12, and the papermaking process is performed by the paper machine 13.

<Raw material slurry preparation process>
The raw material slurry preparation process is a raw material containing a filler, a coagulant and a flocculant, and, if necessary, a sizing agent, a paper strength enhancer, and a dye in a pulp slurry containing pulp as a main raw material for newsprint. This is a step of preparing a slurry. This raw material slurry preparation process has the filler addition process and the flocculant addition process which are demonstrated below in this order. Furthermore, when using multiple types of raw material pulp in the raw material slurry preparation step, it may have a pulp blending step, which will be described later, before the filler addition step, and when using waste paper pulp as a raw material, this waste paper A coagulant may be added to the pulp in advance.

<Filler addition process>
A filler addition process is a process of adding a filler to the pulp slurry containing raw material pulp.

(Raw pulp)
The said raw material pulp may be a well-known thing, The kind and combination can be set suitably. Specifically, waste paper pulp, virgin pulp, or a combination thereof can be used. The above-mentioned waste paper pulp may be derived from any raw material, for example, tea waste paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, flyer waste paper, office waste paper, corrugated waste paper, upper white waste paper, Kent waste paper, imitation waste paper, land ticket waste paper, etc. For example, disaggregated waste paper pulp, disaggregated / deinked waste paper pulp (DIP), or disaggregated / deinked / bleached waste paper pulp. The virgin pulp may be derived from any raw material, for example, hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), softwood unbleached kraft pulp (NUKP), hardwood Chemical pulp such as semi-bleached kraft pulp (LSBKP), softwood semi-bleached kraft pulp (NSBKP), hardwood sulfite pulp or coniferous sulfite pulp; Stone Grand Pulp (SGP), Pressurized Stone Grand Pulp (TGP), Chemi Grand Pulp (CGP) ), Mechanical pulp such as groundwood pulp (GP) or thermomechanical pulp (TMP); pulp produced chemically or mechanically from non-wood fibers such as kenaf, hemp, straw or bamboo. Among these pulps, combined use of waste paper pulp and virgin pulp is preferable, and combined use of waste paper pulp derived from newspaper waste paper and thermomechanical pulp (TMP) is more preferable. Suitable for newspaper papermaking by using wastepaper pulp derived from newspaper wastepaper, whose pulp properties are uniform, with little variation in constituent components, and thermomechanical pulp (TMP) suitable for adjusting the strength of newspaper paper Raw material slurry can be obtained.

(Pulp slurry)
The slurry means a fluid in which a solid content is suspended in a liquid, and the pulp slurry in the production method means a material in which a solid raw material such as the raw material pulp or filler is suspended in water. . As an upper limit of content of the raw material pulp contained in a raw material slurry, 5 mass% is preferable, 4 mass% is more preferable, 3.5 mass% is further more preferable. Moreover, as a minimum of the said content, 0.8 mass% is preferable, 2 mass% is more preferable, and 2.5 mass% is further more preferable. By making content of the raw material pulp contained in the said raw material slurry into the said range, the raw material slurry suitable for the subsequent papermaking process can be obtained.

(Filler)
The filler is added to improve the opacity, smoothness, printability and whiteness of the paper. As the filler used in the production method, recycled particles obtained using papermaking sludge as the main raw material are used. And good. As fillers other than the regenerated particles, clay, talc, calcium carbonate, titanium oxide, white carbon and the like may be used in combination as necessary. Hereinafter, the “regenerated particles” will be described in detail.

(Regenerated particles)
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, and regenerated particles C having a volume average particle size c and regenerated particles having a volume average particle size d larger than the volume average particle size c. D is preferably included. The volume average particle diameter c of the regenerated particles used in the newspaper is preferably 1 μm or more and less than 3 μm, and the volume average particle diameter d is preferably 3 μm or more and 10 μm or less. Here, the “volume average particle diameter” represents the average particle diameter of the regenerated particles in terms of the volume, and in principle, a fixed volume of particles is sieved in order from the smallest, and 50% volume thereof is obtained. It means the particle diameter at the time when the particles corresponding to the above are separated. The volume average particle size can be automatically measured by using a commercially available electrical or optical particle size measuring device. Further, “two types of regenerated particles having different volume average particle diameters” mean particles having two different maximum values in the particle size distribution of all regenerated particles used in the production method. The particle size distribution of the regenerated particles obtained by mixing the regenerated particles C and the regenerated particles D has maximum values in the range of 1 μm or more and less than 3 μm and in the range of 3 μm or more and 10 μm or less, respectively.

  Thus, by including two types of regenerated particles C and regenerated particles D having different volume average particle diameters, regenerated particles having a small particle diameter in a small space between pulp fibers that are not filled with the regenerated particles D having a large particle diameter. C enters and the voids can be filled more densely. Thus, newsprint with high opacity and oil absorption can be obtained by densely filling the gaps between the pulp fibers. Further, by using the filler in which the regenerated particles C and the regenerated particles D having different volume average particle diameters are used in this way, the filler fixing property to the gaps between the pulp fibers is increased, and the particles once fixed in the manufacturing process are spilled off. Phenomenon, that is, generation of paper dust can be reduced. As a result, dirt in the machine system is reduced, and the operability of the machine can be improved by reducing the number of cleanings.

  The ratio of the regenerated particles C and the regenerated particles D is not particularly limited as long as it is determined as appropriate in consideration of the required filling rate, but the upper limit of the ratio of the regenerated particles C to 100 parts by mass of the regenerated particles D is, for example, 500 masses. Part is preferred, 400 parts by weight are more preferred, and 350 parts by weight are even more preferred. Moreover, as said minimum, 100 mass parts is preferable, for example, 200 mass parts is more preferable, 250 mass parts is further more preferable. When the ratio of the regenerated particles C to 100 parts by mass of the regenerated particles D exceeds 500 parts by mass, the amount added is too large with respect to the volume of the generated voids, so that strong fixation cannot be performed, and the filler will fall off. Furthermore, excessive addition of filler weakens the adhesion between pulp fibers, leading to a decrease in strength of the newsprint. On the other hand, if the ratio of the regenerated particles C to 100 parts by mass of the regenerated particles D is less than 100 parts by mass, the voids between the pulp fibers cannot be filled, and the function of improving opacity cannot be sufficiently exhibited.

  The proportion of silica contained in the regenerated particles depends on the volume average particle size of the regenerated particles and the elemental composition thereof, but the upper limit is, for example, preferably 35% by mass in terms of oxide, more preferably 30% by mass, 20 mass% is more preferable. On the other hand, as said lower limit, 9 mass% is preferable, for example. Similarly, the upper limit of the proportion of calcium contained in the regenerated particles is, for example, preferably 82% by mass in terms of oxide, while the lower limit is preferably 30% by mass, more preferably 40% by mass. 60 mass% is more preferable. Similarly, the upper limit of the proportion of aluminum contained in the regenerated particles is, for example, preferably 35% by mass in terms of oxide, more preferably 30% by mass, and further 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. In the three heat treatment steps, a method of adding a coating floss with a clear origin and a preparation step floss by spraying, a method of adding incinerator scrubber lime, and the like can be mentioned. Specifically, in order to adjust the amount of silica contained in the regenerated particles, for example, newsprint manufacturing wastewater sludge containing a large amount of white carbon or the like as an opacity improver may be used. For example, neutral papermaking wastewater sludge or coated paper manufacturing process wastewater sludge may be used. Similarly, in order to adjust the amount of aluminum, for example, acidic papermaking What is necessary is just to use suitably the drainage sludge of the papermaking type | system | group in which the sulfuric acid band is used, and 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 newsprint, the white of the newsprint obtained by using the regenerated particle obtained through a drying process and a heat treatment process of at least three steps is used. Degree and opacity 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 cationic property of the regenerated particles and the anionic property of the silica appropriately inhibit the binding between the pulp fibers and increase the volume of the resulting newsprint. Moreover, the whiteness as a filler can be improved by combining silica. Further, since the silica composite regenerated particles exhibit a high oil absorption, it is possible to hold and dry the absorption drying type printing ink for newspaper printing on the surface of the newspaper, and further improve the printing opacity of the lightweight newspaper. The silica composite regenerated particles have a large specific surface area because the surface of the porous regenerated particles is originally composited with silica. By using this as a filler for internal addition, whiteness and opacity are obtained. And a bulky paper can be obtained.

  The proportion of silica contained in the silica composite regenerated particles depends on the volume average particle size of the regenerated particles and the elemental composition thereof, but as the upper limit, for example, 50% by mass in terms of oxide is preferable, and 49% by mass is more preferable. 48% by mass is preferable. On the other hand, as said lower limit, 10 mass% is preferable, for example, 41 mass% is more preferable, and 42 mass% is further more preferable. If the ratio of the silica component is less than 10% by mass, the silica coating is not sufficiently performed, so that the oil absorption and opacity cannot be improved. On the other hand, if the ratio of the silica component exceeds 50% by mass, the fine silica Particles may become overfilled, which may cause problems that reduce oil absorption and opacity. The proportion of silica contained in the silica composite regenerated particles can be calculated by performing the above-described elemental analysis similar to the proportion of silica contained in the regenerated particles.

  The oil absorption of the silica composite regenerated particles is preferably 50 ml / 100 g or more and 180 ml / 100 g or less. Thus, by making the amount of oil absorption of the silica composite regenerated particles in the above range, the silica composite regenerated particles contained in the obtained newspaper paper absorb the vehicle of the ink impregnated in the paper layer, the organic solvent, etc., Reduces the decrease in printing opacity of newsprint. In addition, by making the oil absorption amount of the silica composite regenerated particles in the above range, the effect of preventing the ink from sinking and blurring can be obtained because the ink dries quickly. In addition, the said oil absorption amount is the numerical value measured based on JIS-K5101-13-1 (2004) "Pigment test method-13th part: Oil absorption amount-Section 1: Refined sesame oil method".

  The amount of oil absorption of the silica composite regenerated particles is appropriately adjusted according to the reaction temperature, addition time, holding time, pH, viscosity, combustion means of the regenerated particles used, particle diameter, etc. in the silica composite regenerated particles manufacturing method described later. Although possible, for example, the silica composite regenerated particles exhibiting a high oil absorption by adjusting the pore volume of 10,000 kg or less to 0.5 cc / g or more and 1.5 cc / g or less in the silica composite process. Can be obtained.

  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 contained in the paper are hard, the wire of the paper machine 13 is likely to be damaged, and this is not preferable because it shortens the life of the wire. However, since the silica composite recycled particles have an appropriate hardness, the wear of the wire is reduced. The life of the wire can be extended.

  The place where the filler is added in the filler addition process may be anywhere after the receiving chest 1 and is preferably between the cleaner 10 and the screen 12 after the pulp slurry is diluted with white water from the wire part of the paper machine 13. .

  In the said manufacturing method, as an upper limit of the addition amount of the said filler contained in a pulp slurry, 9 mass% is preferable with respect to raw material pulp in conversion of solid content, and 7 mass% is more preferable. Moreover, as a minimum of the said addition amount, 2 mass% is preferable and 3 mass% is more preferable. When the addition amount of the filler is smaller than the above lower limit, the gap between the pulp fibers cannot be filled, and the function of improving opacity is not sufficiently exhibited. On the other hand, if the amount of filler exceeds the upper limit, the filler is too much with respect to the volume of the gap between the pulp fibers, so that the filler cannot be firmly fixed to the gap and the filler falls off. Furthermore, excessive addition of filler weakens the adhesion between pulp fibers, leading to a decrease in the strength of the resulting newsprint.

<Coagulant addition process>
The flocculant addition step is a step of adding a flocculant to the pulp slurry after the filler addition step, and the flocculant (A) has a smaller cation charge density than the flocculant (A) and has a weight. The flocculant (B) having a large average molecular weight is added in this order. By adding the flocculant in this way, the flocs of regenerated particles and fine fibers aggregated with the flocculant (A) are fixed to the fibers with the flocculant (B), and the yield of the regenerated particles on the paper is improved. It is possible to obtain newspaper paper with high ash content, which has been difficult with conventional flocculants, without breaking the formation, and to obtain newspaper paper with high opacity and no unevenness of ink density during printing. it can. In particular, since the regenerated particles have an anionic property and a partial cationic property, the yield can be further improved by performing the two-step flock formation and fixing to the fiber as described above.

(Flocculant)
The flocculant is a kind of retention agent, and the filler and pulp fibers in the pulp slurry are adsorbed and cross-linked with each other by the high molecular weight polymer contained in the flocculant to form a relatively large floc. Such a flocculant is not particularly limited as long as it is a water-soluble high molecular weight polymer and exhibits adsorption / crosslinking action. For example, polyacrylamide (PAM), cationic polyacrylate / polyalkylene polyamine complex , Organic polymer flocculants such as polyvinylamine (PVAm), polydiallyldimethylammonium chloride (polydadomac, PDADMAC), polyamine (PAm), polyethyleneimine (PEI), polyethylene oxide (PEO), and cationized starch. . These may be used alone or in combination of two or more. Among these, polyacrylamide (PAM) type flocculants and cationic polyacrylate / polyalkylene polyamine complexes, which are cationic flocculants having a high filler yield effect, are particularly preferred.

(Flocculant (A))
As the flocculant (A), any of the above flocculants can be used, and among them, a cationic polyacrylate / polyalkylene polyamine complex which is effective in improving the yield of regenerated particles is preferable.

  The upper limit of the cationic charge density of the flocculant (A) is preferably 5 meq / g, more preferably 3.5 meq / g, and even more preferably 3.0 meq / g. On the other hand, the lower limit of the cationic charge density is preferably 2 meq / g, more preferably 2.1 meq / g, and even more preferably 2.6 meq / g. When the cation charge density of the flocculant (A) is less than 2 meq / g, the yield of the filler and fine fibers decreases, and when it exceeds 5 meq / g, the fine fibers are collected too much, and the flocculant (B) described later This is not preferable because it inhibits the yield effect. In addition, the said cation charge density is a numerical value measured by the colloid titration method which uses anionic polymer for a regulation liquid.

  The upper limit of the weight average molecular weight of the flocculant (A) is preferably 10 million, more preferably 9,500,000 and even more preferably 9 million. On the other hand, the lower limit of the weight average molecular weight is preferably 7 million, more preferably 7.5 million, and still more preferably 8 million. If the weight average molecular weight of the flocculant (A) is less than 7 million, the effect of the flocculant (A) may not be sufficiently exhibited, and the yield of fillers and fine fibers may decrease, whereas it is larger than 10 million. And flocs become too large, which is not preferable because it inhibits the yield effect of the flocculant (B) described later. In addition, the said weight average molecular weight is the numerical value measured using the gel permeation chromatography method (GPC method).

  The upper limit of the addition amount of the flocculant (A) is preferably 280 ppm, more preferably 245 ppm, and even more preferably 210 ppm with respect to the pure and solid pulp. On the other hand, the lower limit of the amount added is preferably 70 ppm, more preferably 105 ppm, and still more preferably 140 ppm. If the addition amount of the flocculant (A) is less than 70 ppm, the predetermined agglomeration effect may not be sufficiently exhibited, and the yield of fillers and fine fibers may be reduced. On the other hand, if the amount exceeds 280 ppm, the floc becomes too large. Since the yield effect of the flocculant (B) mentioned later is inhibited, it is not preferable.

  The place for adding the flocculant (A) may be anywhere after the filler addition step, for example, before the screen 12 after the filler addition step.

(Flocculant (B))
As the flocculant (B), any of the above flocculants can be used as long as it has a smaller cation charge density than the flocculant (A) and a large weight average molecular weight. Cationic polyacrylamide which is a high cationic flocculant is preferred.

  The upper limit of the cationic charge density of the flocculant (B) is preferably 0.7 meq / g, more preferably 0.6 meq / g, and even more preferably 0.5 meq / g. On the other hand, the lower limit of the cationic charge density is preferably 0.1 meq / g, more preferably 0.2 meq / g, and still more preferably 0.3 meq / g. When the cation charge density of the flocculant (B) is less than 0.1 meq / g, the yield of the filler and the fine fibers is reduced. When the cationic charge density is more than 0.7 meq / g, the formation due to excessive collection of the fine fibers is reduced. This is not preferable because there is a fear that the charge in the system may turn over and troubles such as an increase in defects may occur easily. The method for measuring the cationic charge density is the same as that for the flocculant (A).

  The upper limit of the weight average molecular weight of the flocculant (B) is preferably 18 million, more preferably 17 million, and even more preferably 15.5 million. On the other hand, the lower limit of the weight average molecular weight is preferably 12 million, more preferably 13 million, and even more preferably 14.5 million. When the weight average molecular weight of the flocculant (B) is less than 12 million, the effect of fixing the filler aggregated with the flocculant (A) and the flocs of fine fibers to the fibers is not sufficiently exhibited, and the yield of the filler and fine fibers On the other hand, if it is larger than 18 million, the floc to be formed becomes large and the formation may be destroyed. In addition, the measuring method of a weight average molecular weight is the same as that of the said flocculant (A).

  The upper limit of the addition amount of the flocculant (B) is preferably 240 ppm, more preferably 225 ppm, and still more preferably 210 ppm with respect to pure and solid pulp. On the other hand, the lower limit of the amount added is preferably 150 ppm, more preferably 165 ppm, and still more preferably 180 ppm. When the addition amount of the flocculant (B) contained in the pulp slurry is less than 150 ppm, the effect of fixing the filler aggregated with the flocculant (A) and the flocs of the fine fibers to the fibers is not sufficiently exhibited. On the other hand, if it exceeds 240 ppm, the flocs formed are too large and the formation may be destroyed, which is not preferable.

  The addition place of the flocculant (B) may be anywhere after the addition of the flocculant (A). For example, after the flocculant (A) is added and passed through the screen 12, the front of the paper machine 13 and the like may be placed. Can be mentioned.

  Thus, by using the flocculant (A) and the flocculant (B) in combination, the floc formed by the flocculant (A) is further agglomerated by the flocculant (B) added thereafter, and the pulp The yield of the filler is improved by improving the fixing property of the filler between the fibers. As a result, manufacturing costs are reduced, printing properties such as opacity, whiteness, and oil absorption of the resulting newsprint are improved, and machine operation efficiency is improved by reducing paper dust drop.

<Coagulant addition process>
The coagulant adding step is a step of adding a coagulant to the pulp slurry containing used paper pulp before the filler adding step. In this way, by adding a coagulant before adding the filler, fine pulp fibers derived from waste paper pulp and fine filler form floc-like lumps due to the electrical action of the coagulant, and the yield of the filler is further improved. To do.

(Coagulant)
The coagulant is a kind of retention agent that neutralizes the negative charge on the surface of the pulp fiber or filler and uses spontaneous soft floc generation by van der Waals force. By adding a coagulant, very fine fillers and pulp fibers derived from waste paper pulp coagulate to form relatively small flocs. Such a coagulant is not particularly limited as long as it is a water-soluble polymer and contains a cationic group in the polymer molecule, and exhibits cationic properties when added to pulp. For example, polyacrylamide (PAM ), Polyvinylamine (PVAm), polydiallyldimethylammonium chloride (Polydadomac, PDADMAC), polyamine (PAm) or polyethyleneimine (PEI), etc .; organic coagulant such as sulfate band or polyaluminum chloride Etc. Among these, modified polyethyleneimine is preferable. These may be used alone or in combination of two or more.

  The upper limit of the amount of the coagulant contained in the pulp slurry is preferably 630 ppm, more preferably 595 ppm, and even more preferably 560 ppm with respect to pure and solid pulp. On the other hand, the lower limit of the amount added is preferably 420 ppm, more preferably 455 ppm, and still more preferably 490 ppm. If the addition amount of the coagulant contained in the pulp slurry is less than 420 ppm, there is a risk that the very fine filler derived from waste paper pulp and the floc generation action of the pulp fiber may be insufficient, and if it exceeds 630 ppm, the effect of other papermaking chemicals May interfere.

  The upper limit of the weight average molecular weight of the coagulant is preferably 650,000, more preferably 600,000, and further preferably 550,000. On the other hand, the lower limit is preferably 350,000, more preferably 400,000, and further preferably 450,000. If the weight average molecular weight of the coagulant is less than 350,000, anionic fillers and fine fibers derived from waste paper pulp cannot be sufficiently adsorbed, and the yield of fillers and fine fibers may be deteriorated and foreign matter defects may increase. . Further, if the average molecular weight exceeds 650,000, the effects of other papermaking chemicals such as paper strength agents and sizing agents may be hindered. In addition, the measuring method of a weight average molecular weight is the same as that of the said flocculant (A).

  The upper limit of the cationic charge density of the coagulant is preferably 19.5 meq / g, more preferably 19.0 meq / g, and even more preferably 18.5 meq / g. On the other hand, the lower limit of the cation charge density is preferably 16.5 meq / g, more preferably 17.0 meq / g, and even more preferably 17.5 meq / g. When the cationic charge density of the coagulant is less than 16.5 meq / g, there is a risk that the action of generating very fine filler derived from waste paper pulp and flocs of fine fibers may be insufficient, and it exceeds 19.5 meq / g. Then, there exists a possibility of inhibiting the effect of other papermaking chemicals. The method for measuring the cationic charge density is the same as that for the flocculant (A).

  The place for adding the coagulant may be anywhere before the filler addition step, and examples thereof include blended chest 2 and the like.

<Pulp blending process>
The said manufacturing method may have a pulp compounding process simultaneously with the addition of the said coagulant, or after the said coagulant addition process, when using multiple types of raw material pulp for a raw material. The pulp blending step is a step of adding various pulp slurries to the pulp slurry containing the waste paper pulp before the filler adding step. By adding various pulps in this pulp blending step, it is possible to adjust a pulp slurry that matches the intended paper quality. There is no restriction | limiting in particular as a pulp added in this pulp compounding process, For example, the various raw material pulp mentioned above is mentioned. In order to improve the strength of the obtained paper, for example, softwood bleached kraft pulp (NBKP) or the like may be added, and in order to improve the opacity of the paper and increase the bulk, for example, thermomechanical pulp ( TMP) or the like may be added. This pulp blending step may be performed at the same time as the addition of the coagulant or after the coagulant addition step. For example, the pulp blending step may be performed simultaneously with the addition of the coagulant in the blending chest 2.

<Paper making process>
A conventionally known papermaking process may be appropriately used as the papermaking process in the production method. Specifically, for example, after the raw material slurry prepared in the raw material slurry preparation step is made by a known paper machine 13, a sizing agent is applied to the front and back surfaces of newsprint, and further passed through a calendar device as necessary. For example, applying paper and applying pressure and smoothing treatment.

(Size agent)
As the sizing agent used in the paper making process, a commonly used sizing agent may be appropriately used. Examples of such a sizing agent include oxidized starch, etherified starch, esterified starch, enzyme-modified starch, and cationization. Starch, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl alcohol (PVA), styrene / acrylic acid copolymer, styrene / (meth) acrylic acid copolymer (note that (meth) acrylic acid is “acrylic acid and / Or methacrylic acid.), Styrene / (meth) acrylic acid / (meth) acrylic acid ester copolymer, styrene / maleic acid copolymer, styrene / maleic acid half ester copolymer, styrene / maleic acid Ester copolymers, water-soluble polymers such as polyacrylamide, rosin Tall oil alkyd resin saponified and phthalic acid, anionic low molecular compounds such as saponified petroleum resins and rosins, such as cationic polymers, such as Isojianeto based polymers. Among these, water-soluble polymers are preferable, starch is more preferable, and processed starch in which a carboxyl group, an aldehyde group, a carbonyl group or the like is further introduced into the molecule after being reduced in molecular weight by an oxidation reaction with sodium hypochlorite or the like is further added. preferable. The above sizing agents may be used alone or in combination of two or more. By adding these sizing agents, the vehicle content of cold-set offset ink is quickly absorbed, and even if the amount of printing ink increases due to the use of a high-speed rotary press or the use of a tower press for double-sided color, sufficient absorption is achieved. Since the drying property is expressed and the filler is securely fixed to the fiber, it is possible to prevent the filler from falling off and to ensure excellent printing opacity, printability, and the like.

  In order to further improve the effect of the sizing agent and improve compatibility with ink in offset rotary printing and prevention of the filler from falling off, it is preferable to use a styrene polymer in combination with the sizing agent. By using the styrenic polymer in combination with the sizing agent, the sizing agent can be applied uniformly, the paper surface strength can be improved, and the filler can be prevented from falling off. The blending ratio of the sizing agent and the styrene polymer is preferably 10 parts or more and 15 parts or less of the styrene polymer with respect to 100 parts of the sizing agent in solid content. If the styrenic size is less than 10 parts, it is difficult to sufficiently improve the size and surface strength of the paper, and if it exceeds 15 parts, the cost may increase and the opacity and ink drying may be reduced. is there.

  Examples of the styrenic polymer include styrene / acrylic acid copolymer, styrene / (meth) acrylic acid copolymer, styrene / (meth) acrylic acid / (meth) acrylic ester copolymer, styrene / maleic acid. Examples thereof include a copolymer, a styrene / maleic acid half ester copolymer, and a styrene / maleic acid ester copolymer.

Examples of the coating amount of the sizing agent, preferably per side 0.1 g / ^{m 2} or more 1.0 g / ^{m 2} or less, 0.2 g / ^{m 2} or more 0.75 g / ^{m 2} or less is particularly preferred. If the coating amount of the surface sizing agent is smaller than the above range, sufficient film properties cannot be obtained, and it is difficult to sufficiently improve the surface strength. On the other hand, if the coating amount of the surface sizing agent exceeds the above range, a large amount of mist of the coating liquid containing the surface sizing agent will be generated around the coating equipment, fouling the peripheral equipment, and paper breakage due to dirt There is a risk of paper defects.

  The means for applying the sizing agent is not particularly limited, and examples thereof include a transfer roll coater, an air doctor coater, a blade coater, and a rod coater. Among these coaters, a transfer roll coater type coating apparatus is preferable, and a gate roll coater is particularly preferable. Unlike other coating methods, gate roll coating enables the formation of a highly coatable layer on the newsprint surface even at low coating amounts, and because the coating solution does not have a sudden shear force, it can be used in a circulating manner. It is excellent in the stability of the coating liquid to be applied, and a uniform film can be obtained at high speed.

  Furthermore, in the manufacturing method, the flattening process may be performed by a calendar facility such as a super calendar, a gloss calendar, or a soft calendar. It is possible to further improve the printability of newsprint obtained by performing such flattening. The calender equipment is not particularly limited. For example, for newsprint with a high proportion of waste paper pulp, a soft calender having a low nip pressure and the same tension, high smoothness, and hence excellent weight reduction and color printing suitability is preferable.

<Method for producing regenerated particles>
Here, the above-described method for producing regenerated particles will be described in detail below with reference to FIGS. 2 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 is stored in the silo 30 through the cooler 28 and the particle size sorter 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 set so that the heat treatment temperature increases 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 in 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 of the regenerated particles uses 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 a used paper processing facility. 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 (1), with 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.

  Moisture content (mass%) = (mass before drying−mass after drying) ÷ mass before drying × 100 (1)

  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. The raw material 20 after the unraveling step is preferably 70% by mass as the upper limit of the ratio of the particle diameter of 50 mm or more. 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 raw material was measured, and the total size of the measured values was 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. When the average particle diameter of the raw material 20 is less than 1 mm, excessive heat treatment is likely to occur in the first heat treatment. On the other hand, if the raw material 20 has an average particle diameter of more than 7 mm or a raw material 20 having a particle diameter of 50 mm or more, it is difficult to uniformly heat-treat the raw material 20 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 is easy to 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 the organic matter, and the regenerated particles obtained are uniform and white It is also suitable in that the degree is excellent.

  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 gravity 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. When the temperature of the outer surface of the furnace main body is lower than 260 ° C., there is a possibility that the acrylic organic matter and cellulose in the raw material 20 cannot be sufficiently heat-treated (thermal decomposition or the like). On the other hand, when the temperature of the outer surface of the furnace body exceeds 450 ° C., excessive heat treatment of the raw material 20 may be performed. 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 with an automatic oxygen concentration measuring apparatus (model number “ENDA-5250” manufactured by Horiba, Ltd.). From the viewpoint of preventing excessive heat treatment of the raw material 20, a low oxygen concentration is preferable. The oxygen concentration of the hot air is adjusted to 20.0% or less, and the oxygen concentration of the exhaust gas is also set to 20.0% or less. It is more preferable to manage. On the other hand, if the oxygen concentration of the hot air is less than 5.0% or the oxygen concentration of the exhaust gas is less than 0.1%, the heat treatment of the acrylic organic matter or cellulose does not proceed sufficiently, and the rate of decrease in the calorific value is set to a predetermined value. There is a risk that it may be difficult to adjust to the range, and pyrolysis gas may be ignited (combustion). 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. When the temperature of the hot air is 300 ° C. or higher and the temperature of the exhaust gas is 250 ° C. or higher, the thermal decomposition and volatilization of the acrylic organic matter and cellulose in the raw material 20 are performed reliably. In addition, heat treatment control in the second heat treatment furnace 25 and the third heat treatment furnace 27 is facilitated by reliably performing thermal decomposition and volatilization of the acrylic organic material and cellulose, and generation of carbides that cause a decrease in whiteness, Generation of hard substances due to overcombustion can be suppressed. Furthermore, since the thermal decomposition and volatilization of the acrylic organic material and cellulose are performed reliably, the organic material such as the styrenic organic material and the residual carbon can be gently heat-treated in the second heat treatment furnace 25 and the third heat treatment furnace 27. The generation of residual carbon can be suppressed. However, if the temperature of the hot air exceeds 420 ° C. or the temperature of the exhaust gas exceeds 370 ° C., the pyrolysis gas may be ignited, and the heat treatment energy in the second heat treatment furnace 25 increases, and further, flame retardancy occurs. There is a risk that regenerated particles having properties necessary as an additive or pigment for papermaking cannot be stably obtained. 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. When the rate of decrease in the calorific value is 90% or less, excessive heat treatment is suppressed, and generation of a hard substance is preferably suppressed to 1.5% by mass or less. In this respect, a decrease in the calorific value exceeding 90% means that even the styrenic organic matter in the raw material 20 is pyrolyzed, and therefore, the inside of the furnace body can be ignited by pyrolysis gas such as cellulose ( That is, it is in a high temperature state. On the other hand, if the rate of decrease in the calorific value is less than 20%, the acrylic organic matter that is a high calorific value component in the raw material 20 remains, and the heat treatment temperature in the second heat treatment furnace 25 may vary greatly. . 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 performing the heat treatment so that the unburned rate becomes 30% by mass or less, the heat treatment in the second heat treatment furnace 25 can be performed slowly. However, if the heat treatment is performed until the unburned rate becomes less than 13% by mass, the energy cost in the first heat treatment furnace 24 increases.

  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 to 30 minutes or longer, the acrylic organic matter and cellulose contained in the raw material 20 are slowly pyrolyzed, and the generation of residual carbon is suppressed. In this respect, if the residence time is less than 30 minutes, sufficient heat treatment is not performed and the proportion of remaining carbon increases. On the other hand, if the residence time exceeds 120 minutes, flame retardant carbon is generated by excessive heat treatment, and the whiteness of the obtained regenerated particles may decrease, or the hard substance may increase. 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. When the temperature of the outer surface of the furnace main body is lower than 360 ° C., the styrenic organic matter in the raw material 20 may not be sufficiently heat-treated (such as thermal decomposition). On the other hand, when the temperature of the outer surface of the furnace main body exceeds 550 ° C., the raw material 20 may be excessively heat-treated. 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 by an automatic oxygen concentration measuring device (model number “ENDA-5250” manufactured by Horiba, Ltd.). When the oxygen concentration of the hot air is less than 5.0% or the oxygen concentration of the exhaust gas is less than 0.1%, the heat treatment of the styrene-based organic matter does not proceed sufficiently, and the reduction rate of the calorific value is adjusted to a predetermined range. There is a risk that the whitening will not proceed due to difficulty in firing, and there is a risk that pyrolysis gas may be ignited (combustion). On the other hand, if the oxygen concentration in the hot air (oxygen-containing gas) or exhaust gas is too high, compressed air and its additional equipment are required, the energy cost increases, and the raw material 20 may be burned or hardened. . 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. When the temperature of the hot air is 350 ° C. or higher and the temperature of the exhaust gas is 300 ° C. or higher, the thermal decomposition and volatilization of the styrenic organic matter in the raw material 20 is performed reliably. In addition, since the thermal decomposition and volatilization of the styrene-based organic material is reliably performed, the heat treatment control in the third heat treatment furnace 27 is facilitated, and the generation of carbides that cause a decrease in whiteness and the generation of hard substances due to overcombustion. Can be suppressed. Furthermore, since the thermal decomposition and volatilization of the styrene-based organic material is reliably performed, the organic material such as residual carbon can be gently burned in the third heat treatment furnace 27, and the generation of residual carbon can be suppressed. On the other hand, when the temperature of the hot air is 550 ° C. or lower and the temperature of the exhaust gas is 500 ° C. or lower, the generation of residual carbon in this step can be suppressed, and the heat treatment of the organic matter is performed slowly. The pulverization is suppressed, and the heat treatment degree and the grain alignment of the raw material 20 that forms aggregates or has various properties such as hard and soft can be controlled easily and stably. In this regard, when the temperature of the hot air exceeds 550 ° C. or the temperature of the exhaust gas exceeds 500 ° C., the combustion locally proceeds faster than the particle alignment of the raw material 20 proceeds. It becomes difficult to make the difference in unburnt rate small and uniform. 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 to 30 minutes or longer, the organic material derived from styrene or the like contained in the raw material 20 is slowly heat-treated, and the generation of residual carbon is suppressed. In this regard, if the residence time is less than 30 minutes, sufficient heat treatment is not performed, and the proportion of residual carbon increases. On the other hand, if the residence time exceeds 120 minutes, flame retardant carbon is generated by excessive heat treatment, and the whiteness of the obtained regenerated particles may decrease, or the hard substance may increase.

  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 performing the heat treatment so that the unburned rate of the raw material 20 is 20% by mass or less, the heat treatment (combustion) in the third heat treatment furnace 27 can be performed efficiently in a short time, and the regenerated particles obtained can be obtained. The whiteness can be set to a high whiteness of 70% or more, preferably 80% or more. However, when heat treatment is performed until the unburned rate becomes less than 2% by mass, the energy cost in the second heat treatment furnace 25 increases, the whiteness of the regenerated particles obtained decreases, or the hardness increases. There is a risk that the quality of the regenerated particles may deteriorate.

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. If the average particle diameter is less than 1 mm, the raw material 20 may be overburned in the third heat treatment furnace 27. On the other hand, if the average particle diameter exceeds 5 mm, it becomes difficult to heat-treat (burn) the remaining carbon, the combustion does not proceed to the core, and the whiteness of the obtained regenerated particles may be reduced.

  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 80 to 95 mass%.

  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 this 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 adopted in that the heat treatment efficiency is superior to the external heat kiln furnace. Similarly to the furnace 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 as described above.

  According to the third heat treatment furnace 27 configured as described above, the content charged from the supply port 27A is first lifted and dropped while being fed by the spiral lifter 50 toward the other end by an appropriate amount. In the meantime, the organic component resulting from the raw material 20 can be efficiently contacted with the combustion gas (combustible gas) generated by gasification. Furthermore, since it is in contact with the combustion gas (combustible gas) efficiently by repeating the operation of being subsequently 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. These lifters can also be applied to the first heat treatment furnace and the second heat treatment furnace 25 as appropriate.

  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 with an automatic oxygen concentration measuring apparatus (model number “ENDA-5250” manufactured by Horiba, Ltd.). The oxygen concentration contained in the hot air is preferably a low oxygen concentration from the viewpoint of preventing excessive heat treatment of the raw material 20, and it is more controlled to reduce the oxygen concentration of the hot air (oxygen-containing gas) and exhaust gas. preferable. However, if the oxygen concentration in the hot air (oxygen-containing gas) or exhaust gas is too low, the heat treatment of residual carbon or residual organic matter does not proceed sufficiently, and whitening may not proceed. On the other hand, if the oxygen concentration in the hot air (oxygen-containing gas) or exhaust gas is too high, compressed air and its additional equipment are required, the energy cost increases, and the raw material 20 may be burned or hardened. . Further, in order to increase the oxygen concentration of the exhaust gas, it is necessary to blow excess air into the furnace body, which may cause problems such as a decrease in furnace temperature and difficulty in controlling the furnace temperature. 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. When the temperature of the hot air is 550 ° C. or higher and the temperature of the exhaust gas is 550 ° C. or higher, the heat treatment of the residual carbon and residual organic matter in the raw material 20 is performed reliably. On the other hand, when the temperature of the hot air is 780 ° C. or less and the temperature of the exhaust gas is 780 ° C. or less, the generation of residual carbon can be suppressed, and the heat treatment of the organic matter is performed slowly, and the raw material 20 is pulverized. It is possible to easily and stably control the degree of heat treatment and the grain alignment of the raw material 20 that is suppressed and forms aggregates or has various properties such as hard and soft. In this regard, if the temperature of the hot air exceeds 780 ° C. or the temperature of the exhaust gas exceeds 780 ° C., the combustion locally proceeds faster than the particle alignment of the raw material 20 proceeds. It becomes difficult to make the difference in unburnt rate small and uniform. Moreover, when the obtained regenerated particles are slurried, they may be hardened. 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. The temperature is preferably 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. When the temperature of the outer surface of the furnace main body is 550 ° C. or higher, residual carbon and residual organic substances such as styrene-acryl and styrene that could not be burned in the second heat treatment furnace 25 can be surely burned. 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 to 60 minutes or longer, residual organic matter and residual carbon contained in the raw material 20 are reliably burned, and regenerated particles can be stably produced. On the other hand, if the residence time exceeds 240 minutes, flame-retardant carbon is generated by overcombustion, and the whiteness of the obtained regenerated particles may be reduced, or the hard substance may be increased.

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.

“Hardening substance” means high hardness, wear and damage of papermaking tools and soiling in papermaking systems due to the presence of trace amounts, and wear of coating equipment such as doctors when used as a coating pigment. -It is a substance that causes damage and streak, and specific examples include gehlenite (Ca ₂ Al ₂ SiO ₇ ) and anorsite (CaAl ₂ Si ₂ O ₈ ). 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 preferably pulverized to adjust the average particle size so that the average particle size is 15 μm or less, preferably 1 μm or more and 10 μm or less. If the particle diameter is smaller than 1 μm, the yield may be poor, and foreign matter may be easily formed in the paper machine 13, and if it is larger than 15 μm, the formation may be deteriorated or the strength (tensile strength or tear strength) may be decreased. Is not preferable. The average particle diameter after pulverization is a volume average particle diameter (D50) measured using a particle size distribution diameter (model number: SA-LD-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, it is sorted by a particle size sorter 29 such as a vibration sieve, and stored as regenerated particles in the silo 30.

[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 within the above range, sufficient silica precipitation is obtained on the surface of the silica composite regenerated particles, preventing ink sinking and improving the opacity of newsprint paper. be able to.

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. When mineral acid is added until the pH is less than 8.0, the calcium component contained in the regenerated particles is easily changed to calcium hydroxide, and the resulting silica composite regenerated particles have an excessively reduced particle size or shape. Becomes non-homogeneous, and it is not preferable because yield on paper, generation of paper dust, and sufficient opacity are difficult to obtain. On the other hand, when the pH exceeds 11, the reaction between the alkali silicate and the mineral acid becomes dull, and it becomes difficult to combine silica on the surface of the regenerated particles, and it becomes difficult to obtain sufficient opacity.

  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. If the particle diameter of the silica composite regenerated particles is less than 1.7 μm, the effect of silica composite cannot be sufficiently exhibited, and the effect of improving the oil absorption and opacity is difficult to obtain. Since it becomes larger than the size of the mesh of the network structure to be created, it is not preferable because it becomes difficult to enter and fix this portion.

  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.

<Newspaper>
Since the above manufacturing method has a high yield of filler, newsprint paper having excellent printing characteristics such as opacity and whiteness can be obtained. As a result, the newsprint obtained by the manufacturing method can be suitably used for high-speed offset rotary printing.

The basis weight of the newspaper is a numerical value measured in accordance with the “basis weight measurement method” described in JIS-P8124 from the viewpoint of weight reduction, for example, ensuring paper strength in high-speed rotary printing, and ensuring printing opacity. preferably 38 g / ^{m 2} as a lower limit, 40 g / ^{m 2} is more preferable. On the other hand, as said upper limit, 48 g / m < ² > is preferable and 46 g / m < ² > is more preferable. By setting the basis weight within the above range, it is easy to secure strength in a high-speed offset rotary printing press, and an increase in the weight of paper can be prevented.

  The whiteness of the newspaper is preferably 53% or more, more preferably 54% or more and 58% or less as measured by JIS-P8148 so as not to cause eye strain of the reader. . By setting the whiteness to the above range, a newspaper with good appearance of the printed matter after offset printing, particularly after color printing can be obtained without deteriorating the appearance of the white paper before printing.

  The opacity of the newsprint is preferably higher because it is difficult to see through during printing. For example, “Paper and paperboard-Opacity test method (Paper back of paper) described in JIS-P8149” is preferable. The upper limit of the numerical value measured according to “Reliance)-Diffuse illumination method” is preferably 96%, more preferably 95%. On the other hand, 90% is preferable as the lower limit of the opacity, and 93% is more preferable. By setting the opacity in the above range, newsprint paper with excellent adhesion and strength between pulp fibers can be obtained without increasing the amount of necessary fillers, without causing back-through. Further, the regenerated particles having different volume average particle diameters are combined, and the flocculant (A) and the flocculant (B) in which the cationic charge density decreases in this order and the molecular weight increases in this order in the pulp slurry after the filler addition step. In addition to making the recycled particles paper to fill the gaps in the pulp fiber, the filler yield is improved, the light scattering property is increased, and the light transmission property is lowered. Transparency can be obtained.

  The printing opacity of the newsprint is preferably higher because it is less likely to show through during printing. For example, the lower limit of the numerical value measured according to the printing opacity test method described later is used. 90% is preferable, and 92% is more preferable. Moreover, as said upper limit of opacity, 95% is preferable and 94% is more preferable. By setting the printing opacity within the above range, newsprint paper with excellent adhesion and strength between pulp fibers can be obtained without increasing the required filler without causing show-through. In addition, the decrease in the amount of filler falling off the paper surface can prevent an increase in paper dust during printing and suppress contamination in the machine system during the manufacturing process. Further, the regenerated particles having different volume average particle diameters are combined, and the flocculant (A) and the flocculant (B) in which the cationic charge density decreases in this order and the molecular weight increases in this order in the pulp slurry after the filler addition step. In order to fill the gaps between the pulp fibers, recycled particles are made, and the yield of these fillers is improved, the light scattering property is increased and the light transmission property is lowered. Can be obtained.

The density of the newsprint is 0.56 g / cm ³ or more and 0.70 g / cm as a numerical value measured in accordance with the method described in “Paper and paperboard—Test method for thickness and density” described in JIS-P8118. ³ or less is preferable. By setting the density within the above range, it is possible to prevent the strength of the paper from being lowered, to prevent the paper from being cut off during high-speed rotary printing, and to suppress the generation of paper dust.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

<Manufacture of regenerated particles>
(Production Examples 1-10)
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, wet pulverization was performed to obtain regenerated particle aggregates.

  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 particle aggregate was wet pulverized using a ceramic ball mill, and regenerated particles of Production Examples 1 to 10 shown in Table 1 below were obtained.

(Production Example 11)
In addition, regenerated particles of Production Example 11 were obtained in the same manner as Production Example 2 except that the first heat treatment step was omitted in Production Example 2.

<Manufacture of newsprint>
Example 1
[Raw material slurry preparation process]
The raw material slurry preparation step was performed using an apparatus including an acceptance chest, a blending chest, a first machine chest, a second machine chest, a seed box, a first fan pump, a cleaner, a second fan pump, and a screen in this order. The raw pulp is put into the compounding chest, sent to the first machine chest by the flow pump, further sent to the second machine chest by the flow pump, sent to the seed box by the seed box feed pump, and the first fan. After removing foreign matter by sending it to a cleaner with a pump, it was sent to a screen with a second fan pump to prepare the desired raw material slurry. The raw material slurry preparation process will be described in detail below.

(Process 1)
A pulp slurry was prepared by blending raw pulp with the following proportion in the blended chest.
Softwood bleached kraft pulp (NBKP) 5% by mass
85% by mass of deinked pulp (NDIP) from newspaper wastepaper
Thermomechanical pulp (TMP) 10% by mass

(Process 2)
A coagulant was added to the pulp slurry of the blended chest obtained in step 1. The coagulant is a product name "Himax SC-924" (modified polyethyleneimine, cationic charge density 18.0 meq / g, weight average molecular weight 500,000) manufactured by Hymo Co., Ltd. It added so that it might become (coagulant addition process).

(Process 3)
The pulp slurry of the blended chest after the addition of the coagulant was sent to the first machine chest, and the pH was adjusted to 6-7 with a sulfuric acid band. After this pulp slurry was sent to the second machine chest and subsequently sent to the seed box, an alkyl ketene dimer sizing agent (trade name “AD-1624, manufactured by Japan PMC Co., Ltd.) was added to this pulp slurry with respect to 1 t of pulp solid content. )) Was added in an amount of 0.3 kg (solid content).

(Process 4)
Subsequently, after the pulp slurry obtained in the above step (3) is sent to the cleaner with a first fan pump to remove foreign matter, the regenerated particles obtained by the above production method before the second fan pump in front of the screen, And white carbon were added at the blending ratios shown in Table 2 (filler addition step).

(Process 5)
Furthermore, in front of the screen after the filler is added, as a flocculant (A), the product name “Himoloc FR-740” (cationic polyacrylate / polyalkylene polyamine complex, cationic charge density manufactured by Hymo Co., Ltd.) is used as the flocculant (A). 2.8 meq / g, weight average molecular weight 8.5 million) was added in a pure amount to 175 ppm with respect to the solid pulp. Thereafter, after removing foreign matters through the screen, before sending to the paper machine, the product name “Himoloc ND-270” (cationic polyacrylamide, cationic charge density 0.4 meq / g, manufactured by Hymo Co., Ltd.) is used as the flocculant (B). The weight average molecular weight of 15 million) was added to a pure content of 195 ppm with respect to the solid pulp.

[Paper making process]
The raw material slurry obtained in the raw material slurry preparation step was made with a twin wire paper machine to obtain a base paper having a basis weight of 42 g / m ² . Furthermore, oxidized starch and styrene-based polymer (trade name “SS2712”, manufactured by Seiko PMC Co., Ltd.) as a sizing agent on the surface of the base paper, and 15 parts of styrene-based polymer with respect to 100 parts of oxidized starch in terms of solid content. After mixing and adjusting the concentration by adding water, the above-mentioned base paper was coated so that the dry mass was 0.5 g / m ² per side (1.0 g / m ^{2 on} both sides). I got 1 newspaper.

(Examples 2 to 22)
Except that the flocculant (A), flocculant (B), type of coagulant, addition location, addition amount, presence / absence of addition, and type of regenerated particles were changed as shown in Table 2, and carried out in the same manner as in Example 1. The newsprint of Examples 2-22 was obtained. In addition, when the addition place was the same, the flocculant (B) was added after adding the flocculant (A).

(Comparative Examples 1-6)
In the same manner as in Example 1 except that the flocculant (A), flocculant (B), type of coagulant, addition location, addition amount and presence / absence of addition were changed as shown in Table 2, Comparative Examples 1 to 6 I got a newspaper.

<Physical property evaluation>
The physical properties of the newsprint obtained in the above examples and comparative examples were measured by the following methods. These results are shown in Table 3.

(A) Basis weight Basis weight was measured according to JIS-P8124 (1998) “Paper and paperboard—basis weight measurement method”.

(B) Ash content Ash content was measured based on JIS-P8251 (2003) "Paper, paperboard and pulp-ash content test method-525 ° C combustion method".

(C) Printing Opacity The printing opacity is determined by the JAPAN TAPPI paper pulp test method No. 45: 2000 "Newspaper-opacity test after printing".

(D) Opacity The opacity was measured according to JIS-P8149 (2000) “Paper and paperboard—Opacity test method (backing of paper) —diffuse illumination method”.

(E) Whiteness Whiteness was measured in accordance with JIS-P8148 (2001) “Paper, paperboard and pulp—Method of measuring ISO whiteness (diffuse blue light reflectance)”.

(F) Density Density was measured according to JIS-P8124 (1998) “Paper and paperboard—basis weight measurement method” and JIS-P8118 (1998) “Paper and paperboard—test method for thickness and density”.

(G) Ink concentration Offset printing ink (Dainippon Ink Chemical Co., Ltd.) is placed in the gap between the metal roll and rubber roll using an RI printing aptitude tester (Ishikawajima Industrial Machinery Co., Ltd., model number "RI-2 type"). After applying 0.85 ml of a product name “News Zet Naturalis (Black)” manufactured by the company, it was printed on a test piece of 50 mm in the CD direction and 100 mm in the MD direction at a speed of 30 rpm, and JIS-P8111 (1998) “Paper, Paperboard and pulp-dried for 24 hours in a constant room condition according to "standard conditions for humidity conditioning and testing". The ink density at 25 printing sites randomly selected from this test piece was measured with a Macbeth densitometer, and the average value thereof was determined.
Ink density suitable for offset rotary printing is 1.25 or more and 1.36 or less.

<Quality evaluation>
Moreover, the quality of each newsprint obtained by the said Example and comparative example was investigated based on the following test examples 1-5. The results are shown in Table 4.

[Test Example 1: Ink setting property]
Using an RI printing aptitude tester (made by Ishikawajima Sangyo Co., Ltd., model number "RI-2 type"), for newspaper ink (Dainippon Ink Chemical Co., Ltd., trade name "News Zet Naturalis") After solid printing, the coated paper was superimposed on the printing surface and pressure-bonded at a constant pressure, and the state of ink transfer to the coated paper was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
(Double-circle): The stain | pollution | contamination does not arise at all on the coated paper surface.
○: Slight dirt is generated on a part of the coated paper surface, but there is no practical problem.
Δ: Stain is observed on the entire coated paper surface.
X: Stain on the entire coated paper surface is remarkable.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

[Test Example 2: Ink fillability]
Using an offset printing machine (manufactured by Komori Corporation, model number “Komori SYSTEMC-20”), with newspaper ink (manufactured by Dainippon Ink & Chemicals, Inc., trade name “News Zet Naturalis (ink)”), 16 10,000 copies were printed continuously at a speed of 10,000 copies / hour. The clearness and the shading unevenness of the image of the obtained printed matter were visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
(Double-circle): The image is clear, there is no unevenness in density, and the ink deposition property is excellent.
A: The image is clear, there is almost no unevenness in density, and the ink deposition property is good.
Δ: There are portions where the image is unclear and unevenness in density, and ink inking properties are not good.
X: Overall, the image is unclear, the density unevenness is remarkable, and the ink deposition property is inferior.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

[Test Example 3: Surface strength]
In accordance with JIS-K5701-1 (2000) “Lithographic Ink—Part 1: Test Method”, a color change tester (made by Ishikawajima Industrial Machinery Co., Ltd., model number “RI-1 type”) was used, and ink tack was used. Printing was performed under the condition of 18 single printings. The newspaper paper surface was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: The entire surface of the newsprint is not removed.
○: Slightly removed on a part of the newspaper surface, but there is no practical problem.
Δ: Taken over the entire newspaper surface.
X: Significant removal on the entire newspaper surface.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

[Test Example 4: Uneven ink absorption]
Using an offset printing machine (manufactured by Komori Corporation, model number “Komori SYSTEMC-20”), with newspaper ink (manufactured by Dainippon Ink & Chemicals, Inc., trade name “News Zet Naturalis (ink)”), 160,000 Printing was performed at a speed of parts per hour. The obtained printed matter was visually observed for ink density unevenness and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: There is no unevenness in the ink density, and the image is uniform and clear.
◯: There is almost no ink density unevenness and the image is uniform.
(Triangle | delta): The ink density nonuniformity is recognized in part, and there exists a location where an image is unclear.
X: Overall, the ink density unevenness is remarkable and the image is unclear.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

[Test Example 5: Printing operability]
(1) Cutter tip clogging Using an offset rotary printing press (manufactured by Mitsubishi Heavy Industries, Ltd., model number “LITHOPIA BTO-N4”), printing was performed on newspaper paper of 50 continuous rolls. The presence or absence of clogging of the sword tip was examined and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: No sword clogging occurred.
○: A sword clog occurred only once with one winding.
Δ: Claw tip clogging occurred 2 to 3 times with one winding.
X: Sword tip clogging occurred 4 times or more with one winding.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

(2) Paper dust pilings Paper dust pilings can be printed on a 50-roll newspaper using a web offset printing press (model number “LITHOPIA BTO-4” manufactured by Mitsubishi Heavy Industries, Ltd.). The paper sheet was visually observed for the occurrence / deposition of paper dust in the blanket non-image area, and evaluated based on the following evaluation criteria.
(Evaluation criteria)
(Double-circle): Generation | occurrence | production of paper dust is not recognized at all.
○: Slight generation of paper dust is observed, but no accumulation on the blanket is observed.
(Triangle | delta): Generation | occurrence | production of paper dust is recognized and it has accumulated on the blanket.
X: Accumulation of paper dust on the blanket is remarkable.

(3) Neppari (Blanket adhesive)
Two samples obtained by cutting newspaper paper into a size of about 4 cm in width and about 6 cm in length were prepared and immersed in water for 10 seconds, and then these two samples were quickly brought into close contact with each other. This was passed through a calendar at a linear pressure of 100 kg / cm, dried at room temperature for 24 hours, and then manually peeled off two samples (T peel peel test imitation sensory test). Based on the evaluation.
(Evaluation criteria)
(Double-circle): It did not peel and it did not adhere | attach at all.
○: Although partly adhered, it could be easily peeled off.
(Triangle | delta): There existed a part which has adhere | attached and was hard to peel.
X: Adhered as a whole, and fluffing of fibers from the adhesion surface was observed at the time of peeling.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

  From the above results, in the flocculant addition step, the flocculant (A) and the flocculant (B) are added in this order so that the cationic charge density decreases in order and the weight average molecular weight increases in order. It can be seen that newsprints with improved retention and excellent printing characteristics can be obtained (Examples 1 to 22). On the other hand, when a coagulant is used for either one of the coagulant (A) and the coagulant (B) (Comparative Example 1 and Comparative Example 3), or the cation charge density of the coagulant (A) is the coagulant (B). When the molecular weight of the flocculant (A) is larger than the molecular weight of the flocculant (B) (Comparative Example 2), when the flocculant is added before the filler addition step (Comparative Example 4) ), When the flocculant (A) and the flocculant (B) are not used (Comparative Example 5) and when the regenerated particles are not used as the filler (Comparative Example 6), sufficient effects cannot be obtained. I understand.

  The newsprint paper manufacturing method of the present invention can be suitably used for manufacturing newsprint paper for offset rotary printing at high speed, for example.

DESCRIPTION OF SYMBOLS 1 ... Reception chest 2 ... Compounding chest 3 ... 1st flow pump 4 ... 1st machine chest 5 ... 2nd flow pump 6 ... 2nd machine chest 7 ... Seed box feed pump 8 ... Seed box 9 ... 1st fan pump DESCRIPTION OF SYMBOLS 10 ... Cleaner 11 ... 2nd fan pump 12 ... Screen 13 ... Paper machine 20 ... Raw material 21 ... Storage tank 22 ... Drying device 23 ... Charger 24 ... 1st 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 ... induction 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 (6)

A method for producing newsprint having a raw material slurry preparation step and a paper making step of making a newsprint using the raw material slurry obtained in the raw material slurry preparation step,
The raw material slurry preparation step
(1) A filler addition step of adding a filler to a pulp slurry containing raw material pulp, and (2) a weight average molecular weight of 7 to 10 million in the pulp slurry after the filler addition step, The aggregating agent (A) exhibiting cationic property and the aggregating agent (B) having a weight average molecular weight of 12 to 18 million, water-soluble and cationic and having a smaller cation charge density than the aggregating agent (A). The flocculant addition process in which the above fillers are added in this order. The above-mentioned filler is made of paper sludge as the main raw material, and the regenerated particles obtained through a drying process and at least three heat treatment processes in an environment with an oxygen concentration of 5.0 to 20.0% method for producing newsprint, wherein the early days containing silica playback particles coated with silica. The method for producing newsprint according to claim 1 , wherein the heat treatment temperature in the drying step and each heat treatment step is controlled to be sequentially increased. The method for producing newsprint according to claim 1 or 2 , wherein a ratio of silica contained in the silica composite regenerated particles is 10% by mass or more and 50% by mass or less in terms of oxide. The newsprint paper manufacturing method according to claim 1, wherein the regenerated particles include two types of regenerated particles having different volume average particle diameters. The above-mentioned pulp pulp contains at least a waste paper pulp, and has a cationic charge density of 16.5 meq / g or more and 19.5 meq / g or less and a weight average molecular weight of 350,000 to 650,000 and a water-soluble and cationic coagulant. The method for producing newsprint according to any one of claims 1 to 4 , wherein the newsprint is added in advance. Newsprint obtained by the manufacturing method according to any one of claims 1 to 5 .

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