JP5566703B2 - Newspaper - Google Patents

Description

  The present invention relates to newsprint.

  Conventionally, virgin pulp such as mechanical pulp having thick fibers is often added to raw pulp for the purpose of improving the opacity and strength of newsprint. However, in recent years when recycling of resources in consideration of environmental issues is required, it is desired to recycle waste paper pulp obtained by collecting newspapers and magazines once distributed in a high ratio. Use of the virgin pulp as a raw material for the paper is contrary to the recyclability. On the other hand, with the widespread use of recycled paper, waste paper pulp is repeatedly reused, so breakage of the waste paper pulp during the reuse process is inevitable, and there are many fine fibers and the strength is reduced. Adding such recycled pulp to newsprint papers, while satisfying the above recyclability, leads to a decrease in printability such as paper strength, opacity, oil absorption, etc., resulting in reduced penetration and concealment during printing. At the same time, inconveniences such as fading of the marking surface, missing of halftone dots, and poor appearance are likely to occur.

  In the paper manufacturing industry, attempts have been made to improve the opacity of newsprint by increasing the amount of filler or ash as a measure against the opacity associated with the weight reduction of newsprint. As such a filler, for example, white carbon or calcium carbonate is generally used. However, the mere increase in the filler causes problems that the improvement in opacity reaches its peak, the strength of the newsprint decreases, and the paper dust increases.

  Therefore, the internal addition method of the filler is improved as one proposal for improving these disadvantages. As a method for producing a paper in which a filler is internally added, for example, a technique for producing newsprint paper using white carbon in combination with talc, clay, or kaolin has been proposed (see, for example, Japanese Patent No. 2960001). The white carbon used in these newsprints is a fine one obtained by neutralizing sodium silicate with sulfuric acid and has a smaller particle size than conventional white carbon particles, so it has good light scattering properties. Opacity can be improved.

  In addition, as another technology, newspapers containing white carbon and calcium carbonate as the main filler and containing these main fillers are proposed so that the ash ratio in atomic absorption analysis is 9: 1 to 5: 5. (See, for example, JP-A-2002-201590). These newsprints can be manufactured at low cost by using inexpensive calcium carbonate and processing at pH 6 to 8 with good white carbon yield.

Japanese Patent No. 2960001 JP 2002-201590 A

  However, the newsprint obtained by the above prior art has many gaps between the filler and the pulp fiber, and light passes through these gaps, so that the printing characteristics of newsprint such as opacity and oil absorption are sufficient. Absent. Moreover, in the said prior art, since the adhesivity of the filler between pulp fibers is not enough, paper powder is easy to generate | occur | produce and there exists inconveniences, such as the yield of a filler being bad. In this way, fillers that are not sufficiently fixed between pulp fibers spill from papermaking and become paper dust that accumulates in the machine system and requires periodic cleaning of the machine, leading to a decrease in operating efficiency. To do.

  The present invention has been made in view of these inconveniences, and it is possible to densely fill a gap between pulp fibers and enhance the adhesion of the filler between pulp fibers, thereby improving the opacity and oil absorption of newsprint. The printability can be improved by improving the printability, and there is little paper dust generation at the time of printing, and the printing workability is excellent, and the excellent yield of the filler reduces paper dust and reduces dirt in the machine system. The purpose is to provide newsprint that can improve machine operability.

The invention made to solve the above problems is
Newspaper with pulp as the main ingredient and internal filler,
As the filler, containing regenerated particles obtained using deinked floss as the main raw material,
As this regenerated particle,
Regenerated particles A having a volume average particle diameter a;
Regenerated particles B having a volume average particle size b larger than the volume average particle size a are used,
The volume average particle diameter a is 1 μm or more and less than 3 μm, the volume average particle diameter b is 3 μm or more and 10 μm or less,
The regenerated particles B are silica composite regenerated particles obtained by combining regenerated particles with silica.

  The newspaper uses regenerated particles A and regenerated particles B as fillers internally added, the regenerated particles A have a volume average particle size a, and the regenerated particles B have a volume average particle size b larger than the volume average particle size a. Therefore, the regenerated particles A having a small particle diameter enter the gaps between the pulp fibers that are not filled with the regenerated particles B, and the gaps between the pulp fibers and the unevenness of the paper surface are more densely filled. Newspapers having high opacity and oil absorption and excellent printing characteristics can be obtained. Further, the regenerated particles having such two kinds of volume average particle diameters fill the gaps between the pulp fibers without gaps, whereby the filling structure is reinforced, the regenerative particles adherence is improved, and the paper dust fall is reduced. As a result, the yield of the filler is improved and the raw material cost is reduced. In addition, by reducing the amount of paper dust falling, dirt in the machine system in the paper making process can be reduced, the number of cleanings can be reduced, and the operating efficiency of the machine can be improved.

The volume average particle diameter a of the regenerated particles used in the newspaper is 1 μm or more and less than 3 μm, and the volume average particle diameter b is 3 μm or more and 10 μm or less. By giving these two types of distribution to the volume average particle diameter of the regenerated particles, these large and small regenerated particles are more closely packed in the gaps between the pulp fibers, and the opacity and oil absorption are high, resulting in printing characteristics. Excellent newsprint can be obtained. In addition, the regenerated particles are densely filled in the gaps between the pulp fibers and the yield of the regenerated particles is improved, so that the raw material cost is reduced, and the operating efficiency of the machine is improved due to the reduction in the number of cleanings.

  The mixing ratio of the two kinds of regenerated particles is preferably 100 parts by mass or more and 500 parts by mass or less of regenerated particles A with respect to 100 parts by mass of regenerated particles B. By setting the blending ratio of the two types of regenerated particles in the above range, the regenerated particles A having a small size enter the voids that cannot be filled with the regenerated particles B, and the voids between the pulp fibers are more densely filled. Newspaper with high printing properties and excellent printing characteristics can be obtained. Further, the yield of regenerated particles is improved, so that the raw material cost is reduced and the operating efficiency of the machine is improved due to the reduction in the number of cleanings.

  The regenerated particles B are silica composite regenerated particles in which silica is combined with regenerated particles obtained through dehydration, drying, combustion, and pulverization processes using deinked floss as a main raw material. Since the regenerated particle B has a larger volume average particle diameter b than the regenerated particle A, it is preferable to use a silica composite regenerated particle in which silica is combined with the regenerated particle. This silica composite regenerated particle is originally a porous regenerated particle. Since the surface is coated with porous silica, the specific surface area is large, the light scattering property is high, and the oil absorption is high. Therefore, newsprint with high opacity and oil absorption can be obtained.

  The newsprint may further contain a cationic polymer. The cationic polymer is a kind of so-called yield improver, and has a function of generating flocs by neutralizing negative charges on the pulp fiber and filler surfaces. By including such a cationic polymer, the yield of regenerated particles in the newspaper can be further improved.

  The newsprint has high printing characteristics because it has high adhesion of fillers between pulp fibers, excellent opacity and oil absorption, and generates less paper dust during printing. In addition, since the newsprint is less likely to lose paper dust in the paper making process, the number of machine cleanings is reduced, and the operating efficiency of the machine can be improved. Further, since the newspaper has an excellent yield of regenerated particles, the manufacturing cost can be reduced. As a result, the newsprint can be suitably used as a newsprint for high-speed offset rotary printing that requires high opacity and oil absorption.

It is a schematic diagram of the production facility of regenerated particles used suitably for the present invention. It is a typical schematic diagram of the 2nd combustion furnace of the manufacture equipment of the regenerated particle used suitably for the present invention. (A) is a typical longitudinal cross-sectional view of a 2nd combustion furnace, (b) is a typical expanded view of the inner surface of a 2nd combustion furnace.

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

  The newsprint of the present invention contains pulp as a main raw material and contains recycled particles A and recycled particles B. Moreover, you may contain a silica composite reproduction | regeneration particle | grain or a cationic polymer as needed. These will be described below.

<Pulp>
The pulp used as the main raw material of the newsprint may be a known pulp, and the type and combination thereof can be set as appropriate. Specifically, waste paper pulp or virgin pulp, or a combination thereof can be mentioned.

  The above waste paper pulp may be waste paper pulp 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, Examples include disaggregated waste paper pulp, disaggregated / deinked waste paper pulp (DIP), and disaggregated / deinked / bleached waste paper pulp manufactured from the ground paper waste paper.

  Among these waste paper pulp, waste paper pulp derived from newspaper waste paper or magazine waste paper is preferable, and it is more preferable to use these in combination. This is because waste paper pulp derived from such newspaper waste paper or magazine waste paper has a high recovery rate of waste paper, and the raw material pulp types and fillers that make up waste paper pulp are approximated by each paper manufacturer, and there are few fluctuations in the constituent components. is there. Above all, newsprint paper already contains 50% or more of waste paper pulp, and the content of mechanical pulp and kraft pulp is low, and even if various virgin pulps are used, paper is made once, and its pulp properties Is more preferable in that it is homogenized.

  The virgin pulp may be virgin pulp 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) Chemical pulp such as hardwood semi-bleached kraft pulp (LSBKP), conifer semi-bleached kraft pulp (NSBKP), hardwood sulfite pulp or coniferous sulfite pulp; Stone Grand Pulp (SGP), Pressurized Stone Grand Pulp (TGP), Chemi Grand Pulp Mechanical pulp such as (CGP), groundwood pulp (GP) or thermomechanical pulp (TMP); pulps chemically or mechanically produced from non-wood fibers such as kenaf, hemp, straw or bamboo .

  Among these virgin pulps, mechanical pulp (MP) capable of complementing the reduction in the bulk of newsprint is preferable, and thermomechanical pulp (TMP) suitable for adjusting the strength of newsprint and wastepaper pulp obtained from wastepaper is preferred. More preferred.

  Among these pulps, it is particularly preferable to use waste paper pulp as a main component from the viewpoint of resource saving.

  The upper limit of the used paper pulp content contained in the pulp that is the main raw material of the newsprint is preferably 90% by mass, and the lower limit of the used paper pulp content is preferably 60% by mass, more preferably 70% by mass, 80% by mass is more preferable. By adjusting the content of waste paper pulp contained in the pulp, which is the main raw material of the newsprint, within the above range, it is easy to adjust the strength and bulk while taking into consideration environmental properties such as effective use of resources, The newsprint paper excellent in printability such as property can be obtained.

<Regenerated particles>
The newspaper contains regenerated particles A and regenerated particles B as fillers, and these regenerated particles A and regenerated particles B only have to have different volume average particle diameters as described below, and the materials are the same or different. But you can. Here, the “filler” is a filler added to improve the opacity, whiteness, smoothness, etc. of the paper. Examples of the raw material include clay (white clay), talc (talc), calcium carbonate. , Titanium dioxide or aluminum hydroxide. The “recycled particles” are paper sludge as a main raw material, preferably a deinking floss containing a filler or a pigment separated from pulp fibers in a deinking process of used paper processing equipment as a main raw material. Means that it has been recycled through dehydration, drying, combustion and pulverization processes. In addition, the “papermaking sludge” is a solid content that has flowed out through a wire in a papermaking process, a solid content recovered from wastewater containing a solid content generated in a washing process in a pulping process, It means a mixture of various sludges, such as solids separated and recovered by a solid content separation device utilizing a floating action or the like, and solids removed in the waste paper processing step.

  The regenerated particles A have a volume average particle diameter a. The upper limit of the volume average particle diameter a is preferably less than 3 μm, more preferably 2.5 μm. Moreover, as a minimum of the said volume average particle diameter a, 1 micrometer is preferable. By setting the volume average particle diameter a of the regenerated particles A within the above range, a small space that cannot be filled with the regenerated particles B can be filled. Therefore, since the space | gap between pulp fibers is filled closely, the said newsprint can be provided with high opacity and oil absorption. In addition, the use of the regenerated particles A having such a volume average particle diameter a increases the adhesiveness to the voids, so that the phenomenon that particles once fixed in the manufacturing process spill out, that is, the amount of paper dust generated is reduced. Can do. As a result, dirt in the machine system is reduced, so that the number of cleanings is reduced and the operability of the machine can be improved. When the volume average particle diameter a of the regenerated particles A exceeds the above upper limit, it is not preferable because the particles cannot enter into the small voids and the fixing property is lowered, resulting in a decrease in opacity and oil absorption. On the other hand, if the volume average particle diameter a of the regenerated particles A is smaller than the lower limit, the particle diameter is too small with respect to the voids, and the voids pass through the voids, which is not preferable. On the other hand, if the particle diameter is smaller than the above upper limit, the light scattering action is reduced, so even if fixed, it does not contribute to the improvement of opacity, and the fixing force is weak and easy to fall off. This is not preferable because it may cause generation of paper powder in the system and reduce the operability of the machine.

  The regenerated particles B have a volume average particle diameter b, and the volume average particle diameter b is larger than the volume average particle diameter a. The upper limit of the volume average particle diameter b is preferably 10 μm, and more preferably 7 μm. Moreover, as a minimum of the said volume average particle diameter b, 3 micrometers is preferable and 5 micrometers is more preferable. When the volume average particle diameter b is smaller than the lower limit, it passes through the voids of the pulp fiber and the fixation rate is lowered, which is not preferable. Conversely, if the volume average particle diameter b of the regenerated particles B exceeds the above upper limit, it is not preferable because it cannot enter the voids of the pulp fiber and becomes difficult to fix.

  Thus, by setting the volume average particle diameters a and b within the above range, the regenerated particles A having a small particle diameter enter and adhere to the small gaps where the regenerated particles B having a large particle diameter cannot enter, thereby allowing voids of all sizes. Is densely filled, and the newsprint with high opacity and oil absorption and excellent printing characteristics can be obtained.

  The blending ratio of the regenerated particles A and B is not particularly limited as long as it is appropriately determined in consideration of the required filling rate and the like. For example, the upper limit of the blending amount of the regenerated particles A with respect to 100 parts by mass of the regenerated particles B is 500. Mass parts are preferred, 400 parts by mass are more preferred, and 350 parts by mass are even more preferred. Moreover, as a minimum of the said compounding quantity of the reproduction | regeneration particle | grains A, 100 mass parts is preferable, 200 mass parts is more preferable, 250 mass parts is further more preferable. Thus, by setting the blending ratio of the regenerated particles A and B in the above range, the gaps between the pulp fibers are densely filled with two types of regenerated particles, and the newsprint can have excellent printing characteristics.

  Moreover, as an upper limit of the total addition amount of the said reproduction | regeneration particle | grains A and B, 9 mass% is preferable in conversion of solid content with respect to raw material pulp, and 7 mass% is more preferable. Moreover, as a minimum of the said total addition amount, 2 mass% is preferable and 3 mass% is more preferable. If the total addition amount is less than the above lower limit, the amount of regenerated particles relative to the gaps between the pulp fibers is insufficient, and a large amount of voids that are not filled remains, so that sufficient opacity and oil absorption cannot be obtained, which is not preferable. Conversely, if the total addition amount exceeds the above upper limit, the amount of regenerated particles with respect to the gaps between the pulp fibers is too large, which increases the amount of filler that falls off in the production process or the printing process, and is not preferable because it causes paper dust generation. .

  The regenerated particles preferably contain calcium, silica and aluminum in a mass ratio of 30 to 82: 5 to 40:13 to 30 in terms of oxides, and in a mass ratio of 40 to 60:25 to 40:18 to 25. More preferably. Thus, by containing calcium, silica, and aluminum in the said ratio, the specific gravity of a reproduction | regeneration particle can be lightened, excessive aqueous solution absorption can be suppressed, and the dehydrating property in a dehydration process becomes favorable. The mass ratio of each component can be calculated, for example, by performing elemental analysis at an acceleration voltage (15 KV) using an X-ray microanalyzer (model number: E-MAX · S-2150) manufactured by Horiba, Ltd. .

  Examples of a method for adjusting the mass ratio of the calcium, silica, 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 and a coating with a clear origin in the drying, classification, and firing steps. Examples include a method of containing a floss and an adjustment process floss by spraying, or a method of containing an incinerator scrubber lime. Specifically, as a method for adjusting the calcium contained in the regenerated particles, for example, a neutral papermaking drainage sludge or a wastewater sludge from the coated paper manufacturing process may be used. As a method for adjusting the silica, for example, As an opacity improver, newsprint manufacturing wastewater sludge containing a large amount of white carbon or the like may be used. Also, as a method for adjusting the aluminum, for example, a sulfuric acid band such as acidic papermaking is used. What is necessary is just to use suitably the drainage sludge of the papermaking type | system | group which is used, and the wastewater sludge in the high quality papermaking process with much talc.

<Method for producing regenerated particles>
(Dehydration process)
The regenerated particles A and B are dehydrated and dried by using papermaking sludge as a main raw material, preferably using a deinking floss separated from pulp fibers in a deinking process of a used paper processing facility for producing used paper pulp as a main raw material. Obtained by burning and grinding. The above regenerated particles are different from calcium carbonate, talc, and clay, which are generally used as fillers in the past, and have different opacity and excellent opacity. Therefore, the opacity and oil absorption of the newspaper are increased, and the amount of filler added Can be reduced. For example, the production method described in Japanese Patent No. 4087431 can be used as appropriate for the production method of the regenerated particles. A more suitable production example will be described below with reference to FIG.

  The deinking floss as the main raw material 10 of the regenerated particles generally contains about 95 to 98% by mass of water, and therefore, flocculant is added to form flocs for dehydration. The dehydration treatment may be performed in a single stage or multiple stages, but if the floc is solidified, carbonization unevenness will occur in the subsequent carbonization step. Therefore, dehydration is performed in multiple stages, and the moisture content is preferably 25 to 45% by mass. Is preferably about 30 to 40% by mass. If the moisture content after dehydration is less than the above lower limit, the cost required for dehydration increases. Conversely, if the moisture content exceeds the upper limit, the cost required in the next drying step increases and the particle size after drying varies. This is not preferable because it causes a problem.

  It is preferable that the raw material after such dehydration has a mean particle size of 3 mm or more and 40 mm or less using a pulverizer (or a pulverizer). In addition, it is preferable that the particle diameter of a raw material is uniform. If the average particle diameter is less than 3 mm, overcombustion tends to occur. On the other hand, if it exceeds 40 mm, it is difficult to uniformly heat the raw material core, which is not preferable. In addition, the said average particle diameter and the ratio of a particle diameter are the values measured based on JIS-Z8801-2: 2000.

  Moreover, it is preferable to granulate the deinking floss after the dehydration treatment, and it is more preferable to classify the granulated product to have a uniform particle size. In addition, granulation can use a normal granulation equipment suitably, for example, granulation equipment, such as a rotation type, a stirring type, and an extrusion type, is mentioned.

(Heat treatment process for organic components)
The dehydrated product obtained in the dehydration process is then sent to the combustion process. However, an organic component heat treatment step for heat-treating the organic component in the paper sludge (preferably heat treatment at a heat treatment temperature of 200 ° C. to 300 ° C. in an atmosphere having an oxygen concentration of 0.2 to 20%) is provided before the combustion step. It is preferable that the first combustion step of burning paper sludge at a combustion temperature of 300 ° C. to 550 ° C. (preferably, burning in an atmosphere having an oxygen concentration of 0.2 to 20%), and the paper making obtained in the first combustion step. It is preferable that the combustion process includes at least two stages including a second combustion process for reburning sludge.

According to the knowledge of the present inventors, the various organic components (organic substances) contained in the papermaking sludge have an organic component composed of an acrylic material having a calorific value peak around 220 ° C., and a calorific value around 320 ° C. Contains organic components composed of cellulose and the like having a peak, and styrene-based materials having a calorific value in the vicinity of 420 ° C., and burns organic components that are pyrolyzed at 200 ° C. to 300 ° C. In this case, ignition and excessive combustion occur and combustion control becomes difficult, so that not only the whiteness is lowered, but also so-called hard substances such as Ca ₂ Al ₂ SiO ₇ (Gelenite) and CaAl ₂ Si ₂ O ₈ (anocite). ), Which leads to the generation of a hard substance, and by heat treatment before the combustion process, these high calorific value components can be previously removed from the papermaking sludge, It found that it is possible to manufacture stably a playback particles with the required properties as a filler for paper by the process. Above all, the Ca ₂ produced by overcombustion in the first combustion step and the second combustion step by removing the above components by heat treatment so that the reduction rate of the calorific value of the paper sludge is 20 to 70%. It is more preferable that the production of Al ₂ SiO ₇ (gerenite) and CaAl ₂ Si ₂ O ₈ (anosite) be 2.0% by mass or less.

  The apparatus used in the heat treatment step of the organic component is not particularly limited. For example, a direct heating rotary kiln, an indirect heating rotary kiln, an air flow dryer, a fluidized bed dryer, an oscillating fluid dryer, a rotary / aeration rotary dryer (cyclone) Etc. can be used as appropriate. Among these, a direct heating type rotary kiln is preferable in terms of high thermal efficiency and easy operation.

(Combustion process)
The heat-treated deinking floss is then sent to the combustion process. For the combustion process, for example, a normally used incinerator such as a rotary kiln, a fluidized bed furnace, a floating furnace, a stoker furnace, or the like can be appropriately used. Among these, a combustion method by indirect heating using a hot air furnace or an electric furnace is preferable in terms of easy control of the firing temperature and fine adjustment of the degree of firing.

  The combustion process can be performed in one stage, but at least two stages are preferable, and it is more preferable that the combustion process is performed by continuous equipment. As described above, by continuously performing at least the combustion process in two or more stages, the combustion unevenness of the organic matter hardly occurs and uniform combustion becomes possible. In the present invention, the first combustion is performed in the internal heat kiln furnace 14, and the subsequent second combustion is performed in the external heat kiln furnace 32.

  The upper limit of the furnace temperature of the first combustion furnace 14 is preferably 550 ° C, more preferably 510 ° C. Moreover, as a minimum of the said furnace temperature, 300 degreeC is preferable and 400 degreeC is more preferable. Thus, by setting the furnace temperature in the above range, organic components such as styrene-based substances having a calorific value peak near 420 ° C. can be sufficiently pyrolyzed to suppress the formation of residual carbon that is difficult to burn. it can. The hot air blown into the first combustion furnace 14 is preferably 0.2% by volume to 20% by volume as the oxygen concentration.

  The upper limit of the furnace temperature of the second combustion furnace 32 is preferably 800 ° C., and more preferably 750 ° C. Moreover, as a minimum of the said furnace temperature, 550 degreeC is preferable and 600 degreeC is more preferable. The in-furnace temperature of the second combustion furnace 32 is preferably higher than the in-furnace temperature of the first combustion furnace 14 in order to burn residual organic matter that has not been combusted in the first combustion furnace 14, particularly residual carbon. . If the combustion temperature is less than 550 ° C., the residual organic matter is not sufficiently burned. On the other hand, if the combustion temperature exceeds 800 ° C., the problem that the particles become hard is likely to occur. The oxygen concentration in the second combustion furnace 32 is preferably 5% by volume to 20% by volume, and more preferably 10% by volume to 20% by volume. The residence time (combustion time) in the second combustion furnace 32 is preferably 60 minutes or more, more preferably 60 minutes to 240 minutes, still more preferably 90 minutes to 150 minutes, and particularly preferably 120 minutes to 150 minutes. Thus, residual carbon can be efficiently burned by making residence time (combustion time) in the 2nd combustion furnace into the above-mentioned range.

  The oxygen concentration in the combustion process is reduced by being consumed by a burner or the like in the combustion process, but the necessary oxygen concentration can be maintained or adjusted by appropriately blowing or exhausting an oxygen-containing gas such as air. That's fine. Further, by blowing or exhausting the oxygen-containing gas, the temperature in the combustion process can be finely adjusted, and the regenerated particles can be uniformly burned without unevenness.

  In the above production method, it is preferable to remove foreign matters that are inappropriate as a raw material for regenerated particles. For example, sand, plastic in the pulper, screen or cleaner process before the deinking process of the used paper pulp manufacturing process It is preferable to remove foreign substances such as metal. In particular, iron content causes a decrease in the whiteness of the regenerated filler due to oxidation. Therefore, it is preferable to avoid iron contamination as much as possible and selectively remove it. Specifically, by designing or lining the surface of the machine used in each process with materials other than iron, it is possible to prevent iron from being mixed into the system due to wear during use of the machine, and further, drying and For example, a high magnetic material such as a magnet may be installed in the classification equipment to selectively remove iron.

  As a method for aligning the particle size of the regenerated particles with the volume average particle size a or the volume average particle size b which is the object of the present invention, known pulverization and classification means may be appropriately used. In addition, coarse particle aggregates and fine particles that are inappropriate for the intended regenerated particles may be fed back to the remanufactured production process and reused.

(Classification process)
The regenerated particles obtained by the above production method form a regenerated particle aggregate in which several individual particles are aggregated, and have an irregular shape such as a lump-like mass. It is preferable to adjust the particle diameter of the obtained regenerated particle aggregate by pulverizing the volume average particle diameter to 1 to 10 μm by a known pulverization method. If the volume average particle size is smaller than 1 μm, the yield is poor and it is not preferable because it is likely to be a foreign substance in the paper machine system. If it is larger than 10 μm, the formation is deteriorated and the strength (tensile strength and tear strength) may be reduced. This is not preferable. The particle diameter of the regenerated particles is a volume average particle diameter measured by a laser analysis type particle size distribution measuring apparatus “SALD-2200 type” manufactured by Shimadzu Corporation. Thus, since the regenerated particles have an irregular shape and an appropriate volume average particle diameter, the opacity and oil absorption can be improved and the paper thickness of newsprint can be easily obtained.

<Silica composite regenerated particles>
Recycled particles B used for the newspaper are composed of paper sludge as a main raw material, preferably deinked floss as a main raw material, and silica combined with regenerated particles obtained through dehydration, drying, combustion, and pulverization steps. Silica composite regenerated particles are preferred. In this way, by combining silica with the surface of the regenerated particles, the binding between fibers can be appropriately inhibited by the cationic property of the regenerated particles and the anionic property of the silica, and the volume of the resulting newspaper can be increased. . Moreover, the whiteness as a filler can be improved by combining silica. Although white paper opacity tends to decrease due to this increase in whiteness, the use of silica composite regenerated particles with high oil absorption makes it possible to hold and dry absorption dry printing ink for newspaper printing on the surface of newspaper, making it lightweight. It is possible to further improve the printing opacity of simple 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. In the present invention, by using silica composite regenerated particles as the regenerated particles B, not only the above-described effect of improving opacity by combining regenerated particles having different volume average particle diameters, but also the opacity of silica composite regenerated particles and Oil absorbency is added as a synergistic effect, and newsprint paper with better printing characteristics can be obtained.

  The silica contained in the silica composite regenerated particles can be used without particular limitation as long as it is not naturally produced silica but synthetic silica by some chemical reaction. Examples of such synthetic silica include colloidal silica, silica gel, and anhydrous silica. These synthetic silicas have excellent properties such as high specific surface area, high gas adsorbing ability, fineness, permeability to pores and large adsorbing power, high adhesion, or high oil absorption. . Among these synthetic silicas, for example, colloidal silica is an anhydrous silicic acid sol obtained by removing impurities from a silicic acid compound, and adjusting the pH and concentration to stabilize the sol. It means amorphous silica having a shape such as a regular shape. Silica gel means hydrous silicic acid obtained by decomposing sodium silicate with an inorganic acid. Anhydrous silica means that obtained by hydrolysis of silicon tetrachloride. These silicas may be used individually by 1 type, and may be used in combination of 2 or more type.

  The silica composite regenerated particles preferably have a ratio of calcium, silica (silicon), and aluminum of 30 to 80:10 to 50: 7 to 20 (mass%) in terms of oxide. This can be calculated by performing elemental analysis at an acceleration voltage (15 KV) using an X-ray microanalyzer (model number: E-MAX · S-2150) manufactured by Horiba, Ltd., and converting the oxide.

  The proportion of the silica component contained in the silica composite regenerated particles depends on the volume average particle size of the regenerated particles and the elemental composition thereof, but the silica equivalent in terms of oxide after the silica component is deposited on the surface of the regenerated particles. By setting the ratio within the above range, it is possible to improve the printing opacity of newsprint using the silica composite recycled particles. Especially, it is preferable that the ratio of the said silica component shall be 41.0-49.0 mass%, and it is more preferable to set it as 42.0-48.0 mass%. When the proportion of the silica component is less than 10.0% by mass, the silica is not sufficiently precipitated, and the desired oil absorption and opacity cannot be obtained, while the proportion of the silica component exceeds 50.0% by mass. And excessively fine silica particles are not preferable because the amount of oil absorption and opacity are reduced.

  The oil absorption of the silica composite regenerated particles is preferably 50 to 180 ml / 100 g. Thus, when the amount of oil absorption of the silica composite regenerated particles is within the above range, when the filler is used as an internal additive, the filler absorbs the vehicle portion of the ink impregnated in the paper layer, the organic solvent, and the like. As a result, it is possible to suppress the decrease in the printing opacity of the paper, and at the same time, the effect of preventing ink drying and blurring can be obtained. When the oil absorption is less than 50 ml / 100 g, the above effect cannot be obtained sufficiently, and the silica composite regenerated particles tend to inhibit the ink absorption and drying properties, which is not preferable. In addition, when the oil absorption amount exceeds 180 ml / 100 g, the ink absorbability is high, so that the ink sinks and the so-called color developability is inferior.

  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 it is possible, for example, by adjusting the pore volume of 10,000 kg or less to 0.5 to 1.5 cc / g in the silica composite process, it shows a high oil absorption and improves the opacity of the paper Silica composite regenerated particles can be obtained, and the newspaper containing the silica composite regenerated particles can obtain high opacity.

  Moreover, since the surface of the filler is coated with silica, the silica composite regenerated particles can reduce the wear of the wire (net part) and can extend the life of the wire. If the filler particles added to the paper are hard, the wire of the paper machine is likely to be damaged and the wire life is shortened, which is not preferable. However, the silica composite recycled particles can reduce the wear of the wire, thus extending the life of the wire. Can be made.

<Method for producing silica composite regenerated particles>
For example, the method described in Japanese Patent No. 3907688 or Japanese Patent No. 4087431 can be appropriately used as a method of combining silica on the surface of the regenerated particles. However, the following production method is preferred in that silica composite regenerated particles having better opacity can be obtained.

  As a method for producing the silica composite regenerated particles used in the newspaper, the regenerated particles obtained by the above production method are added and dispersed in an aqueous alkali silicate solution to form a slurry, and in a temperature range of 50 ° C. to 100 ° C. with stirring. A method of adding a mineral 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. Below, this manufacturing method is explained in full detail.

  The volume average particle diameter of the regenerated particles used in the method for producing the silica composite regenerated particles is preferably 1.0 μm to 10.0 μm. The particle size of the regenerated particles is a volume average particle size measured by a laser analysis type particle size distribution measuring apparatus “SALD-2200 type” manufactured by Shimadzu Corporation. When the particle size of the regenerated particles used is smaller than 1.0 μm, there is a possibility that a sufficient particle size may not be obtained at the time of silica composite, and there is a possibility of clogging into a glass state when silica is composited. On the other hand, when the volume average particle diameter is larger than 10.0 μm, the particle diameter of the silica composite regenerated particles is large and cannot enter the gaps between the pulp fibers, which causes a decrease in the opacity of the newsprint. .

Although the alkali silicate aqueous solution used for the manufacturing method of the said silica composite reproduction | regeneration particle | grain is not specifically limited, For example, a sodium silicate solution (No. 3 water glass) is desirable at the point which is easy to acquire. The concentration of the alkali silicate solution is preferably 3 to 10% by mass as the silicic acid content (in terms of SiO ₂ ) in the aqueous solution. When the concentration of the alkali silicate solution exceeds 10% by mass, the formed regenerated particles and silica composite particles are not inorganic fine particles / silica composite aggregates, but the regenerated particles are covered with white carbon, which becomes the core material. This is not preferable because the porosity and optical properties of the particles are not exhibited. On the other hand, if the concentration is less than 3% by mass, the silica component in the composite particles decreases, and it becomes difficult to form regenerated particles coated with silica, which is not preferable.

  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 to 14% by mass. 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.

  The solid content ratio of the alkali silicate aqueous solution to the regenerated particles is preferably 100: 5 to 100: 20. When the solid content ratio of the alkali silicate aqueous solution to the regenerated particles is less than 100: 5, silica precipitation on the surface of the obtained silica composite regenerated particles is lowered and the effect of improving opacity is low, which is not preferable. On the other hand, when the solid content ratio exceeds 100: 20, the amount of oil absorption of the resulting silica composite regenerated particles is increased, and the ink absorbability is increased. Absent.

The temperature of the aqueous alkali silicate solution when the regenerated particles are added to the aqueous alkali silicate solution is not particularly limited. The said temperature can also be made into 50 degreeC or more, for example, and can also be heated after reproduction | regeneration particle addition. Among them, it is preferable to add regenerated particles in a state in which an alkali silicate aqueous solution is preliminarily heated to 50 ° C. or more because the fluidity is improved by heating and the slurry can be easily homogenized. In addition to the above, the slurry may be heated and stirred after preparing a homogenized slurry by adding regenerated particles. 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.) in the factory, the heating time can be shortened and the production 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 other mineral acids, and dilute sulfuric acid is preferred from the standpoint of cost and ease of handling. As the concentration of the mineral acid, for example, when dilute sulfuric acid is used, a concentration of about 4 to 10 N is preferable. If the concentration of dilute sulfuric acid is less than 4N, the reaction progresses slowly. On the other hand, if the concentration exceeds 10N, it is not preferable because the silica composite regenerated particles obtained by local reactions are indefinite or unevenly distributed. . Moreover, since silica precipitates in a short time, so that there is much addition amount of a mineral acid, what is necessary is just to adjust an addition rate suitably according to the target conditions. However, since the regenerated particles used as the core material contain calcium, aluminum, and silica as constituent elements, addition of an excessive concentration of mineral acid is not preferable because the regenerated particles may be altered.

  The mineral acid may be added in one step, but it is desirable to add it in two or more steps.

  When the mineral acid is added in one step, it is preferable to set the addition amount so that the addition time of the mineral acid is 40 minutes or more while the pH is lowered by 1.

  In the case where the mineral acid is added in two stages, it is preferable that the amount of the mineral acid added in each stage is equal in view of obtaining a homogeneous silica composite. In addition, after the first stage addition (addition until the mineral acid has a neutralization rate of 20 to 50% with respect to the alkali silicate aqueous solution), a holding time of about 5 to 20 minutes is made and held in the silica complex reaction. By providing a state, silica is uniformly compounded on the surface of the regenerated particles, and by further adding the mineral acid in the second stage, the silica is further laminated and compounded more uniformly on the surface of the regenerated particles. Can be combined.

  It is preferable to set the addition amount of the mineral acid so that the time required for the addition of the mineral acid in the first stage is 10 minutes to 45 minutes in terms of uniformly combining silica on the surface of the regenerated particles. Even when adding a mineral acid in the second stage or more, setting the addition amount of the mineral acid so that the time required for the addition of the mineral acid is about 10 to 120 minutes to reduce the pH by 1, This is preferable in that silica is homogeneously combined.

  50-100 degreeC is preferable as reaction temperature at the time of adding the said mineral acid as a temperature of a slurry, for example, and 50-98 degreeC is more preferable. The reaction temperature affects the formation of silica, the crystal growth rate, and the mechanical strength of the formed silica composite regenerated particles. When the reaction temperature is less than 50 ° C., the rate of silica formation / growth does not occur or is slow, the silica composite regenerated particles have poor silica composite properties, and the silica is not sufficiently composited. However, it is not preferable because the silica composite is fragile. On the other hand, when the reaction temperature exceeds 100 ° C., since it is an aqueous reaction, an autoclave must be used and the reaction process becomes complicated, which is not preferable. In addition, when the reaction temperature exceeds 100 ° C., the reaction proceeds excessively to form a dense silica composite regenerated particle form, and the opacity of the resulting silica composite regenerated particle is lowered, which is not preferable.

  Further, the reaction temperature when adding the mineral acid in two stages is such that the slurry temperature when adding the mineral acid in the first stage is 50 ° C. to 75 ° C., and the slurry when adding the mineral acid after the second stage. It is preferable to raise the temperature by 10 ° C. or more than at least the first stage. Specifically, for example, the first stage slurry liquid temperature is 50 ° C. to 75 ° C., the second stage slurry liquid temperature is 70 ° C. to 100 ° C., and the slurry liquid temperature is set at the final stage of the reaction. The temperature may be 90 ° C or higher and 98 ° C or lower. Thus, by setting it as the said temperature range, a more homogeneous silica composite reproduction particle can be obtained.

  In the method for producing silica composite regenerated particles, the pH of the final reaction solution is preferably 8.0 to 11.0, more preferably 8.3 to 10.0, and even more preferably 8.5 to 9.0. 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, if the pH exceeds 11.0, 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 upper limit of the volume average particle size of the silica composite regenerated particles obtained by the above production method is preferably 10 μm, more preferably 7 μm, although it depends on the particle size of the regenerated particles combined with silica. On the other hand, the lower limit of the volume average particle diameter is preferably 1.7 μm, and 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 is difficult to enter and fix this portion.

  In the above production method, in order not to form an unreacted zone, it is preferable to appropriately employ a stirring means such as, for example, generating a turbulent flow by reversing the stirring blades or providing a baffle plate in the stirring tank.

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

  Exceeding the knowledge that the pore volume of all fine pores of the internally added fine particles has been an index of oil absorption and opacity, the present inventors have found that the actual oil absorption is only the pore volume of inorganic fine particles. In addition, it has been found that it is also influenced by the ability to retain oil between the particles of inorganic fine particles. As a result, the silica composite regenerated particles that can be suitably used in the present invention preferably have a pore radius of 10,000 angstroms or less.

  The upper limit of the pore volume of the silica composite regenerated particles obtained by the above production method is a measured value using a mercury intrusion porosimeter (“PASCAL 140/240” manufactured by Terumo), and the pore volume in a region of 10,000 kg or less. 1.5cc / g is preferable, 1.45cc / g is more preferable, and 1.35cc / g is further more preferable. 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. If the pore volume is less than 0.5 cc / g, sufficient oil absorption cannot be obtained. On the other hand, if it exceeds 1.5 cc / g, the oil absorption is improved, but the opacity tends to decrease. Each is not preferable in terms of points.

<White carbon>
The newspaper can further contain other fillers. Examples of other fillers include clay (white clay), talc (talc), calcium carbonate, titanium dioxide, aluminum hydroxide, or white carbon. Of these, white carbon is preferred. White carbon can further improve the opacity, smoothness, printability and whiteness of the newsprint due to its porous aggregation structure. The upper limit of the white carbon content is preferably 4% by mass, and more preferably 3% by mass. On the other hand, as a minimum of the above-mentioned content, 0.5 mass% is preferred and 1 mass% is more preferred. If the white carbon content is less than the above lower limit, the gap between the pulp fibers cannot be filled, and the function of improving the opacity of the newsprint is low, which is not preferable. On the contrary, if the content of white carbon exceeds the above upper limit, the amount of white carbon is too much for the size of the gap formed by the pulp fibers, so that it cannot be reliably embedded between the gaps. It is not preferable because there is a risk that the filler that falls off during production and use may increase, and when the content of white carbon is too large, the content of pulp fibers is relatively lowered and the strength between the pulp fibers is lowered. However, it is not preferable because the strength of the paper itself is lowered.

<Cationic polymer>
The newspaper may further contain a cationic polymer. The cationic polymer is a kind of so-called yield improver and has a function of generating a small floc by neutralizing the negative charge on the pulp fiber and the filler surface. The yield of regenerated particles can be improved by blending such a cationic polymer in the paper making process of the newspaper.

  The cationic polymer is not particularly limited as long as it is a water-soluble polymer, contains a cationic group in the polymer molecule, and exhibits cationic properties when added to pulp. Examples of such cationic polymer include cationic polyacrylamide, polyacrylate polyalkylene polyamine complex, cationic polyamine resin, cationic polyamine polyamide resin, cationic modified starch, styrene acrylic resin, and cationic thermosetting resin. Etc.

  The upper limit of the amount of the cationic polymer added is preferably 800 ppm, more preferably 700 ppm, based on the solid content of the pulp. On the other hand, the lower limit of the addition amount is preferably 200 ppm, more preferably 400 ppm. If the addition amount of the cationic polymer is smaller than the above range, it is difficult to obtain the effect of improving the yield of regenerated particles, silica composite regenerated particles, etc. Conversely, if the addition amount of the cationic polymer exceeds the above range, the texture becomes This is not preferable because it may deteriorate.

  The upper limit of the weight average molecular weight of the cationic polymer is preferably 16 million, and more preferably 12 million. On the other hand, the lower limit of the weight average molecular weight is preferably 8 million, more preferably 8.5 million. If the weight average molecular weight of the cationic polymer is less than 8 million, the effect of using the cationic polymer is not sufficiently exhibited. On the other hand, if the weight average molecular weight is larger than 16 million, the desired effect cannot be improved so much and the cost is high. It is not preferable because there is a risk of becoming. By using such a cationic polymer in the papermaking process, the yield effect of the regenerated particles is improved, and as a result, the opacity, paper strength or drainage of the newspaper is improved.

  The cationic polymer is added at a stage after the raw pulp is blended in a machine chest, before being sent to the seed box, the first fan pump, and the cleaner, and then supplied to the next second fan pump. The addition of the filler to be used is preferable from the viewpoint of improving the yield of the filler. In addition to the effect of improving the opacity and oil absorption by combining the regenerated particles with different volume average particle diameters and filling the gaps of the pulp fibers, the filler yield is improved by using the cationic polymer, and the light scattering property of the newspaper is improved. While improving, light transmittance is reduced and the outstanding printing characteristic can be provided.

<Newspaper>
The newsprint paper can adjust the ash content in the newsprint paper by adjusting the addition amount of the filler such as regenerated particles or white carbon described above. The upper limit of the ash content after ashing at 525 ° C. measured according to “Paper, board and pulp-ash content test method” described in JIS-P8251 in the newspaper is preferably 15% by mass, and 13% by mass. Is more preferable. On the other hand, the lower limit of the ash content is preferably 6% by mass, and more preferably 7% by mass. In this way, by setting the ash content in the newsprint within the above range, the newsprint can have high opacity and oil absorption. If the ash content is smaller than the above lower limit, the opacity is lowered, which is not preferable. On the contrary, if the ash content exceeds the upper limit, the opacity increases, but the adhesion between the pulp fibers decreases, leading to a decrease in paper strength. It is not preferable. In the newspaper, the ash content can be adjusted by adding the regenerated particles A and B.

  Moreover, it is preferable to contain silicon in the ratio of 40 mass% or more and 60 mass% or less (oxide conversion) and calcium in the ratio of 20 mass% or more and 40 mass% (oxide conversion) or less among the ash content of the newspaper. When silicon and calcium are contained in the above range in the ash content of the newsprint, the newsprint exhibits a suitable ink adsorptivity in rotary printing and can achieve high opacity. If the content of silicon and calcium is less than the above range, ink adsorbability and opacity are lowered, which is not preferable. The components contained in the ash are measured by analyzing 0.2 g of ash with an energy dispersive X-ray analyzer (model number ENERGY EX-250, Horiba, Ltd.) (50 times), for example. can do.

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 the lower limit, more preferably 40 g / ^{m 2,} whereas preferably 48 g / ^{m 2} or less as the upper limit, 46 g / ^{m 2} or less is more preferable. If the basis weight is less than the above lower limit, for example, it is difficult to ensure the strength in a high-speed offset rotary printing press, which is not preferable. On the other hand, if the upper limit is exceeded, the weight of the paper increases, which goes against the recent reduction in weight and resources. This is not preferable.

  The whiteness of the newspaper is preferably 53% or more, more preferably 54 to 58%, as measured by JIS-P8148 so as not to cause eye strain on the reader. If the whiteness is less than 53%, not only the appearance of the white paper before printing may be deteriorated but also the appearance of the printed matter after offset printing, particularly after color printing, may be unfavorable.

  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. If the opacity is less than the above lower limit, it is not preferable because it tends to cause show-through. On the other hand, if the opacity exceeds the upper limit, the necessary filler is increased, and as a result, the adhesion between the pulp fibers decreases and the newspaper This is not preferable because the strength of the paper is lowered. By combining the regenerated particles A and the regenerated particles B, the regenerated particles A and the regenerated particles B are paper-made so as to fill the gaps between the pulp fibers, the filler yield is improved, the light scattering property is increased and the light transmission is increased. Due to the reduced nature, the newsprint can have very high opacity.

  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. If the printing opacity is less than the above lower limit, it is not preferable because it tends to cause show-through. On the other hand, if the printing opacity exceeds the upper limit, the necessary filler is increased, and as a result, the adhesion between pulp fibers is reduced. This is not preferable because it reduces the strength of the newspaper and increases the paper dust at the time of printing due to the removal of the filler from the paper surface, and also causes stains in the machine system in the manufacturing process and deteriorates operability. . By combining the regenerated particles A and the regenerated particles B, the regenerated particles A and the regenerated particles B are paper-made so as to fill the gaps between the pulp fibers, the yield of these fillers is improved, the light scattering property is increased and the light transmittance is increased. Therefore, the newsprint paper can obtain extremely high printing opacity.

The density of the newsprint is preferably 0.56 to 0.70 g / cm ³ as a numerical value measured according to the method described in “Paper and paperboard—Test method for thickness and density” described in JIS P8118. . If the density is less than 0.56 g / cm ³ , the paper strength is lowered, which may cause a paper break in high-speed rotary printing or a problem that paper dust is generated. On the other hand, if the density is more than 0.70 g / cm ³ , it is not preferable because the print-through after printing is likely to occur, the rigidity is lowered and the printing workability may be lowered.

<Method of manufacturing newsprint>
As the method for producing the newspaper, a conventionally known production method may be appropriately used. Specifically, for example, after preparing a pulp slurry to which a dye, a retention agent or the like is added as necessary and making a paper with a known paper machine, a surface sizing agent is applied to the front and back surfaces of newsprint, and further necessary Accordingly, the newspaper may be manufactured by passing the paper through a calendar device and applying pressure and smoothing.

  Examples of the surface sizing agent include oxidized starch, etherified starch, esterified starch, enzyme-modified starch, cationized starch, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl alcohol (PVA), styrene / acrylic acid copolymer, Styrene / (meth) acrylic acid copolymer ((meth) acrylic acid means “acrylic acid and / or methacrylic acid”), styrene / (meth) acrylic acid / (meth) acrylic acid ester Copolymers, styrene / maleic acid copolymers, styrene / maleic acid half ester copolymers, styrene / maleic acid ester copolymers, water-soluble polymers such as polyacrylamide, rosin, tall oil and phthalic acid, etc. Anions such as saponified alkyd resin, saponified petroleum resin and rosin Low molecular compounds, such as cationic polymers, such as Isojianeto polymers and the like, which may be used alone or simultaneously. 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. Among these surface sizing agents, water-soluble polymers are preferable, and starch is more preferable.

  As the starch used as the surface sizing agent, a conventionally used modified starch is preferably exemplified. For example, by oxidation reaction with sodium hypochlorite or the like, a low molecular weight, a carboxyl group in the molecule, an aldehyde And starch having been introduced with a group, a carbonyl group or the like.

As a weight average molecular weight of the starch used as said surface sizing agent, 300,000-3 million are preferable. The starch having such a weight average molecular weight can improve the absorption drying property by incorporating the solvent component into the paper while keeping the ink component on the paper surface, in addition to the covering property on the paper surface. The viscosity of the starch (10%), preferably not more than 30 × ¹⁰ -3 Pa · s, more preferably ^{15 × 10 -3 ~25 × 10 -3} Pa · s. The starch having such a viscosity can remain on the paper surface without penetrating into the paper because of its high viscosity, improving the fixing property of the filler to prevent the filler from falling off and increasing the opacity of the newspaper. be able to.

  Moreover, it is preferable to use a styrenic polymer together with starch from the viewpoint of further improving the size, compatibility with ink in offset rotary printing, and the effect of preventing the filler from falling off. When oxidized starch and styrene-based polymer are used as the surface sizing agent, the starch can be applied uniformly, the surface strength can be improved, and the filler can be prevented from falling off. As a compounding ratio of the oxidized starch and the styrene-based sizing agent, 10 to 15 parts of the styrene-based sizing agent is preferable with respect to 100 parts of the oxidized starch as a solid content. If the styrene-based size is less than 10 parts, it is difficult to sufficiently improve the paper size and surface strength. If the styrene-based size is more than 15 parts, the cost may increase and the opacity and ink drying may be reduced. This is not preferable.

  Examples of the styrenic polymer include a styrene / acrylic acid copolymer and a styrene / (meth) acrylic acid copolymer (where (meth) acrylic acid means “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 copolymer, etc. Is done.

Examples of the solid coating amount of surface 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. When the coating amount of the surface sizing agent is smaller than the above lower limit, it is not preferable because sufficient film property cannot be obtained and the surface strength cannot be sufficiently improved. On the other hand, if the coating amount of the surface sizing agent exceeds the above upper limit, a large amount of mist of the coating liquid containing the surface sizing agent is generated around the coating equipment, fouling peripheral devices and paper breakage due to dirt. This is not preferable because there is a risk of paper defects.

  The means for applying the surface 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, coating by the film transfer method, particularly coating by a gate roll, is suitable for forming a highly coatable layer on the newspaper paper surface even with a low coating amount. Therefore, it is preferable because a coating film to be circulated is excellent in stability and a uniform film can be obtained at a high speed.

  Further, the newspaper can be flattened by a calendar facility such as a super calendar, a gloss calendar, or a soft calendar. By performing the flattening process using such a calendar facility, the printability of the newspaper can be further improved. The calender equipment is not particularly limited, but for the newsprint with a high proportion of used 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.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the following Examples and Comparative Examples, “part” or “%” indicates “part by mass” or “% by mass” unless otherwise specified, and “volume average particle diameter” is manufactured by Shimadzu Corporation. It was measured by a laser analysis type particle size distribution measuring apparatus “SALD-2200 type”.

<Manufacture of regenerated particles>
Deinking floss (derived from the waste paper treatment process for producing waste paper pulp) is used as the main raw material, and these mixtures are dehydrated so that the moisture content after the dehydration process is 35% by mass, and the production equipment of FIGS. 1 and 2 After the organic component heat treatment step (280 ° C., oxygen concentration 12% by volume), the first combustion step (400 ° C., oxygen concentration 12% by volume) and the second combustion step (680 ° C., oxygen concentration 12% by volume) Then, wet pulverization was performed to obtain a regenerated particle aggregate.

  The internal heat kiln used in the heat treatment step of the organic component is an internal heat kiln furnace in which the main body is placed horizontally and rotates around the central axis, and raw materials such as deinking floss are supplied from a raw material supply port at one end of the internal heat kiln furnace. A parallel flow system that supplies hot air while supplying air was adopted. The internal heat kiln used in the first combustion process and the second combustion process is an internal heat kiln furnace in which the main body is placed horizontally and rotates around the central axis, and the external heat kiln furnace used in the second combustion process is An external thermoelectric kiln furnace with a parallel lifter inside was adopted. The combustion temperature in the first combustion process was measured at the outlet of the primary combustion furnace, and the combustion temperature in the second combustion process was measured at the outlet temperature of the secondary combustion furnace. As for the oxygen concentration, the outlet oxygen concentration of the primary combustion furnace and the outlet oxygen concentration of the secondary combustion furnace were measured, respectively.

  The obtained regenerated particle aggregate was wet pulverized using a ceramic ball mill, and further classified to obtain regenerated particles (Production Examples 1 to 5). The volume average particle diameter of each regenerated particle is shown in Table 1 below.

<Manufacture of silica composite regenerated particles>
The regenerated particles (volume average particle diameter 2 μm) of Production Example 2 were used as a slurry solution (slurry concentration 20% by mass), a 38% by mass sodium silicate solution (No. 3 water glass), which is an alkali silicate aqueous solution, and the slurry solution ( Slurry concentration of 20% by mass) is mixed so that the solid content ratio between the regenerated particles and the alkali silicate is 100: 5, and further diluted water is added to obtain a reaction start concentration (slurry concentration) of the slurry composed of the alkali silicate and the regenerated particles. 11 mass%), and the mixture was heated and stirred to adjust the slurry liquid temperature to 55 ° C. The pH at the start of the reaction was 10.7. Next, dilute sulfuric acid (7N) was added as a mineral acid over 22 minutes while stirring until the alkali silicate neutralization rate became 33%, and a primary reaction was performed. Further, the slurry was heated and stirred until the liquid temperature of the slurry reached 93 ° C. and then held for 10 minutes. Thereafter, dilute sulfuric acid (7N) was added over 45 minutes until the pH reached 8.5 to obtain silica composite regenerated particles. The obtained silica composite regenerated particles had a volume average particle size of 5 μm (Production Example 8).

  While following the above measures, the solid content ratio between the regenerated particles and the alkali silicate, the concentration of the regenerated particles and the alkali silicate at the start of the reaction, the alkali silicate neutralization rate in the primary reaction, the reaction end pH, the addition rate of dilute sulfuric acid The silica composite regenerated particles of Production Examples 6, 7, 9, 10, and 11 were obtained by appropriately changing and adjusting the amount. The volume average particle diameters of the obtained silica composite regenerated particles are shown in Table 2 below. The slurry was stirred using a known mixer, the pH of the slurry was measured with a pH meter manufactured by Horiba, Ltd., and the reaction temperature was measured with a known thermometer.

<Production of newsprint>
Example 1
Containing 5% by mass of softwood bleached kraft pulp (NBKP), 85% by mass of deinked pulp (NDIP) made of used newspaper, and 10% by mass of thermomechanical pulp (TMP). S. A pulp slurry adjusted to F (based on JIS-P8121) was obtained. To this pulp slurry, the regenerated particles of Production Example 2 and the silica composite regenerated particles of Production Example 8 described above were added at a ratio of 0.5: 1, and the pH was adjusted to 6 to 7 with a sulfuric acid band. A cationic polymer having a solid content of 600 ppm (“Polymin PR8150” manufactured by BASF Japan Ltd.) was added to the pulp, and a base paper having a basis weight of 42 g / m ² was obtained with a twin wire paper machine. Furthermore, as a surface sizing agent, oxidized starch and styrene polymer (“SS2712” manufactured by Seiko PMC Co., Ltd.) are mixed in solid content so that 100 parts of oxidized starch is 15 parts of styrene polymer, and water is added to adjust the concentration. After the adjustment, the 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) to obtain the newsprint of Example 1.

(Examples 2 and 3)
Newspapers of Examples 2 and 3 were obtained in the same manner as in Example 1 except that the addition ratio of regenerated particles (mass ratio of regenerated particles A: B) was changed.

(Examples 4 and 5)
Newspapers of Examples 4 and 5 were obtained in the same manner as in Example 3 except that the addition amount of the cationic polymer was changed.

(Example 6)
Newspaper paper of Example 6 was obtained in the same manner as in Example 3 except that white carbon (volume average particle size: 18 μm, manufactured by Eliere Paper Chemical Co., Ltd.) was added.

(Example 7)
Newspaper paper of Example 7 was obtained in the same manner as in Example 3 except that the cationic polymer was not added.

(Examples 8 to 21)
Newspaper papers of Examples 8 to 21 were obtained in the same manner as in Example 1 except that the kind of regenerated particles, the addition ratio, and the total addition amount were changed.

(Comparative Examples 1 and 2)
Newspapers of Comparative Examples 1 and 2 were obtained in the same manner as in Example 1 except that the type and addition ratio of regenerated particles were changed.

(Comparative Example 3)
Newspaper paper of Comparative Example 3 was obtained in the same manner as in Example 1 above, except that white carbon (volume average particle diameter: 18 μm, manufactured by Eliere Paper Chemical Co., Ltd.) was used instead of the regenerated particles.

〔quality evaluation〕
About the quality of each newsprint obtained in Examples 1 to 21 and Comparative Examples 1 to 3, the following items were measured to evaluate the workability. The results are shown in Table 4 below.
(1) Basis weight Basis weight was measured based on “basis weight measurement method” described in JIS-P8124.

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

(3) Print opacity The print opacity is JAPAN TAPPI No. Measured according to No. 45.

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

(5) Whiteness Whiteness was measured in accordance with “Measuring method of paper, paperboard and pulp-ISO whiteness (diffuse blue light reflectance)” described in JIS-P8148.

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

(7) Workability Workability is printed on a 50-roll newsprint using an offset rotary printing press (model number: LITHOPIA BTO-4, manufactured by Mitsubishi Heavy Industries, Ltd.). The presence / absence of generation / deposition was visually observed 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.

  The “total addition amount” and “addition amount” of the filler shown in Table 3 above indicate the solid content addition amount (kg (solid content) / pulpton) of the filler per completely dry pulp ton.

  It can be seen that each of the newspapers of Examples 1 to 21 has high printing opacity, good workability, and excellent printing characteristics as newspaper for offset rotary printing. In particular, it has been confirmed that the quality of the newspaper is greatly influenced by adjusting the volume average particle diameter and the addition amount of the regenerated particles. One of the volume average particle diameters of the two types of regenerated particles is 1 μm or more and less than 3 μm. In addition, when the other was 3 μm or more and 10 μm or less, it was shown that extremely high printing characteristics can be exhibited. In addition, the amount of ash in newspapers can be adjusted by adjusting the amount of filler added. When the amount of ash increases, the opacity increases, and when the amount of ash is 8.8-15%, there is less generation of paper dust. It turns out that the workability of newsprint is excellent.

  On the other hand, since the volume average particle diameters of the two kinds of recycled particles are the same in the newspapers of Comparative Examples 1 and 2, the gaps between the pulp fibers cannot be densely filled, and the opacity of the newspapers is insufficient. Further, the newsprint of Comparative Example 3 does not contain regenerated particles having two different volume particle sizes, and the white carbon has a large volume particle size, so that the gaps between the pulp fibers cannot be densely filled. It can be seen that the opacity of the paper is insufficient, and the printing workability is poor due to the removal of the filler from the paper surface.

  The newsprint of the present invention can be suitably used for, for example, high-speed offset rotary printing.

  DESCRIPTION OF SYMBOLS 10 ... Raw material, 12 ... Storage tank, 14 ... 1st combustion furnace (internal heat kiln furnace), 20 ... Hot-air generating furnace, 22 ... Recombustion chamber, 26 ... Heat exchanger, 28 ... Induction fan, 30 ... Chimney, 31 ... External heat jacket, 32 ... second combustion furnace (external heat kiln furnace), 34 ... cooler, 36 ... particle size sorter, 42 ... heat treatment furnace (internal heat kiln furnace), 43 ... hot air generator

Claims (3)

Newspaper with pulp as the main ingredient and internal filler,
As the filler, containing regenerated particles obtained using deinked floss as the main raw material,
As this regenerated particle,
Regenerated particles A having a volume average particle diameter a;
Regenerated particles B having a volume average particle size b larger than the volume average particle size a are used ,
The volume average particle diameter a is 1 μm or more and less than 3 μm, the volume average particle diameter b is 3 μm or more and 10 μm or less,
Newsprint paper , wherein the regenerated particles B are silica composite regenerated particles obtained by combining regenerated particles with silica . The newspaper according to claim 1, wherein the content of the regenerated particles A is 100 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the regenerated particles B. Furthermore, the newsprint of Claim 1 or Claim 2 containing a cationic polymer.

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