JP2009057667A - Newsprint paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide newsprint paper which reduces a cost by cyclic usage of resources, has little blanket stain by pitch and paper dust, printing white spots etc., excellent ink absorption and ink drying properties and high opacity and little print through. <P>SOLUTION: The newsprint paper is obtained by adding a filler to pulp, the pulp contains a wastepaper pulp derived from at least gypsum board wastepaper and at least calcium sulfate as a filler. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to newsprint. More specifically, cost reduction is achieved through the recycling of resources, blanket stains due to pitch and paper dust, printed white spots, etc. are also excellent, and ink absorption and ink drying properties are also excellent. The present invention relates to a news paper which is particularly suitable for high-speed offset rotary printing.

  Due to environmental problems in recent years, there has been a movement to collect waste office paper generated from the office, for example, throughout the building for the purpose of environmental protection, resource protection, and garbage reduction. As usage increases more and more, the ratio of used paper to paper is also increasing.

  In addition, from the viewpoints of resource saving, transportation cost reduction, and raw material cost reduction, the weight of each paper is increasing year by year. Furthermore, at the paper mill, the production ratio of recycled paper using waste paper pulp and the ratio of waste paper to paper are increasing, and the production speed of the paper manufacturing process has been increased more and more to improve paper production efficiency. Yes. Under such circumstances, the demand for newsprint is also progressing in the direction of weight reduction and higher blending of used paper. For example, while reducing the weight of newsprint to increase the number of pages per copy without increasing the weight burden at the time of newspaper delivery, the proportion of used paper has been increasing to cope with environmental problems. The speed of offset rotary printing presses and the colorization of paper are also progressing.

  However, various new problems have emerged in newsprint due to the increase in the ratio of used paper, the increase in the speed of offset rotary printing presses, and the colorization of paper.

  Along with the increase in the ratio of used paper, the content of used wastepaper and coated printing paper with a coating layer in raw materials that have been used mainly for newspaper wastepaper has increased. Synthetic rubbers such as latex and synthetic pitches derived from synthetic resins are remarkably increased. Also, coating means frequently used to obtain a high-definition printed surface with the recent colorization of the paper surface has spurred an increase in the composite pitch.

  The synthetic pitch tends to be sticky, and is a major cause of paper breakage in the speedup of an offset rotary printing press.

  Conventionally, as a method of removing adhesive foreign matter (pitch) at the manufacturing stage of dinking pulp, for example, a method of adding an adhesive removal agent during the production of used paper pulp (see Patent Document 1), A method of adding a densifying agent and a flocculant (see Patent Document 2), a method of binding a magnetic substance to an adhesive in a pulp slurry (see Patent Document 3), and the like have been proposed.

However, all of the above methods suppress the expression of adhesive foreign matter by adding a new chemical at the used paper processing stage, so that the operation becomes complicated and the production cost increases due to the chemical addition. Have
Japanese Patent Laid-Open No. 2003-20584 JP 2002-201579 A JP-A-10-298882

  On the other hand, in the gypsum board factory, waste materials and scraps of gypsum board used as building materials have been disposed of in landfills or incinerators in the past. However, it is difficult to secure new disposal sites due to social constraints. Further, in landfill disposal, there is a problem that the paper constituting the gypsum board rots and gives off a bad odor, and in incineration disposal, there is a problem that sulfur is released from the chimney and sulfuric acid mist is generated. For this reason, the disposal of waste gypsum board is becoming more difficult, and an urgent plan for the countermeasure is desired.

  In addition, the amount of waste gypsum board generated tends to increase year by year, and recycling and effective use of such waste gypsum board is a serious issue for gypsum board factories.

  Although the waste gypsum board contains paper as a main component, it contains a large amount of calcium sulfate (gypsum), so that a large amount of combustion ash (inorganic matter) remains even when burned, and the effect of volume reduction is low. Therefore, efforts such as utilizing this combustion ash as a raw material for cement and soil improvement have been made, but since combustion ash is an auxiliary agent in these methods, a large amount of use is not expected. The burned ash is disposed of in the landfill as described above.

  As a method for effectively utilizing the waste gypsum board pulp and calcium sulfate, it is possible to disperse the waste gypsum board in an aqueous solution and use it as an internal filler for raw pulp and paper, but it contains a large amount of calcium sulfate. In the first place, it is difficult to disaggregate and disperse the waste gypsum board into an aqueous solution, and the calcium sulfate contained causes clogging of the strainer and the screen, resulting in difficulty in operation.

  In this way, it is extremely difficult to recycle waste gypsum board with conventional methods, and the calcium sulfate obtained by these methods is not suitable for papermaking pigments and fillers, and quality stability is improved. It was lacking.

  The present invention has been made in view of the above-described conventional technology, and in the past, after reducing the volume by burning, waste gypsum board that has been disposed of in landfill, especially gypsum from the waste gypsum board. By collecting the raw material from the gypsum board waste paper after collection and separation, and using calcium sulfate (gypsum) derived from the gypsum board waste paper as a filler, the cost can be reduced by the recycling of resources, and by using pitch and paper dust An object of the present invention is to provide newsprint paper that is less susceptible to blanket stains, printing white spots, etc., has excellent ink absorbability and ink drying properties, has high opacity and little show-through, and is particularly suitable for high-speed offset rotary printing.

The present invention
Newspaper paper with filler added to pulp,
The pulp contains at least waste paper pulp derived from waste gypsum board paper,
The newsprint is characterized by containing at least calcium sulfate as the filler.

  In this specification, “waste gypsum board” refers to waste material of gypsum board composed of a composite of paper and calcium sulfate (gypsum) used as building materials, gypsum board end materials, etc. “Recycled gypsum board paper” refers to a residue containing a large amount of gypsum board base paper with calcium sulfate (gypsum) attached to the surface after the gypsum is collected and separated from the waste gypsum board.

  According to the present invention, it is possible to reduce the cost by recycling the resources, there are few blanket stains due to pitch and paper dust, printing white spots, etc., and the ink absorption and ink drying properties are excellent, and the back surface is highly opaque. Newspapers that are less likely to be missing and that are particularly suitable for high-speed offset rotary printing are provided.

(Embodiment)
In the newsprint of the present invention, a filler is internally added to the pulp, and the pulp contains at least waste paper pulp derived from gypsum board waste paper, and the filler contains at least calcium sulfate.

  First, the pulp used in the present invention will be described. The pulp constituting the newsprint of the present invention includes at least waste paper pulp derived from waste paper from gypsum board.

  In the present invention, even when using waste paper pulp containing at least waste paper pulp derived from gypsum board waste paper as described above, there is a problem due to resin pitch or synthetic pitch due to the action of calcium sulfate added as a filler to be described later. It does not occur, greatly contributes to effective use of resources, and can reduce costs. In particular, newsprint paper has a high recovery rate as waste paper, and is said to be an excellent student of recycling. According to the present invention, circulation use of newsprint paper can be further promoted.

  Waste paper pulp derived from waste gypsum board waste paper is obtained, for example, by using waste paper raw materials containing gypsum board waste paper to at least a waste paper treatment process including a disaggregation process, a rough selection process, a deinking process, a fine selection process, a dehydration concentration process, and a bleaching process. It is preferable that

  In particular, it is preferable to use a hole screen having a hole diameter of 1.0 to 2.0 mm, for example, and a slit screen having a slit width of 0.2 to 0.5 mm in combination in the rough selection step. By using such a screen in the rough selection process, it is possible to suitably select excessive calcium sulfate or calcium sulfate fixed to pulp fibers. In addition, for example, the deinking step is performed by a flotation treatment method, and generation of bubbles in the flotation treatment is performed so that the bubble diameter is 5 to 50 mm. It is more preferable because it can be performed.

  As described above, by combining the screen process in the coarse selection process and the flotation process with the bubbles of a predetermined diameter in the deinking process, it becomes possible to efficiently discharge excessive and excessive calcium sulfate to the outside of the system. Reduced paper strength, blanket stains due to pitch and paper dust, printed white spots, etc., excellent ink absorbability and ink drying, high opacity and very low back-through, high-speed offset Newspaper that is more suitable for rotary printing can be obtained.

  In the present invention, in addition to the waste paper pulp derived from the above-mentioned gypsum board waste paper, for example, tea waste paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, leaflet waste paper, office waste paper, corrugated waste paper, upper white waste paper, Kent waste paper, imitation waste paper, ground One or two or more kinds of waste paper pulps such as disaggregated waste paper pulp, disaggregated / deinked waste paper pulp, and disaggregated / deinked / bleached waste paper pulp produced from ticket waste paper can be used.

  The ratio of the waste paper pulp in the total amount of the pulp is preferably 50 to 100% by mass, but is further 60 to 100% by mass, particularly 70 to 100% by mass from the viewpoint of realizing resource saving and cost reduction. % Is preferred.

  In addition, the waste paper pulp derived from the waste paper of the gypsum board is such that the ratio of the waste paper of the gypsum board used as the raw material to the total amount of the pulp is 2% by mass or more, further 3% by mass or more, 50% by mass or less, and further 45 It is preferable to adjust and use so that it may become below mass%. If the amount of the waste paper pulp derived from the waste paper of gypsum board is less than 2% by mass, it is difficult to obtain the effect of saving resources and the effect of calcium sulfate fixed to the waste paper pulp derived from waste paper of the gypsum board, and the operation is complicated. There is a risk of becoming. Conversely, if the amount of waste paper pulp from gypsum board waste paper exceeds 50% by mass, it will be difficult to remove calcium sulfate outside the system in waste paper pulp processing, causing in-process fouling and unstable operation. There is a risk of becoming.

  Further, in the present invention, in addition to the waste paper pulp containing the waste paper pulp derived from the above-mentioned gypsum board waste paper, as a pulp which is a constituent component of newsprint, for example, stone grand pulp (SGP), pressurized stone ground pulp (PGW), refiner Machines such as Grand Pulp (RGP), Chemi Grand Pulp (CGP), Thermo Grand Pulp (TGP), Grand Pulp (GP), Thermo Mechanical Pulp (TMP), Chemi Thermo Mechanical Pulp (CTMP), Refiner Mechanical Pulp (RMP) Pulp: Hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), softwood unbleached kraft pulp (NUKP), hardwood semi-bleached kraft pulp (LSBKP), conifer semibleached kraft pulp (NSB P), and various known pulps such as chemical pulps such as hardwood sulfite pulp and coniferous sulfite pulp, and as long as the object of the present invention is not impaired, one or more of these are appropriately selected. The ratio can be adjusted appropriately and used.

  In the newsprint of the present invention, a filler is internally added to the pulp, and at least calcium sulfate is contained as the filler, and the calcium sulfate is preferably made of gypsum derived from waste gypsum board paper.

  Calcium sulfate made of gypsum from gypsum board waste paper is relatively heavy with a specific gravity of about 2.3. For example, in a disaggregation process, excessive particles are crushed finely with a high-concentration pulper. By using a hole screen having a hole diameter of 1.0 to 2.0 mm, and further using a combination of slit screens having a slit width of 0.2 to 0.5 mm, it is selectively excluded from the system. Can be discharged.

  The calcium sulfate discharged out of the system by the screen treatment in the rough selection process has a relatively large particle size and is recycled as a raw material for the gypsum board. Calcium sulfate discharged in the deinking process has a relatively small particle size, and may be washed away during internal addition or may reduce the paper strength of the resulting newspaper. It is preferable to adjust so that it is not too much.

  In the present invention, calcium sulfate discharged out of the system in the coarse selection step can be suitably used by further performing atomization treatment such as wet pulverization. Furthermore, the calcium sulfate may be subjected to a classification process or the like.

  On the other hand, the calcium sulfate remaining in the system is physically or chemically fixed to the waste paper pulp fiber, and its average particle size is relatively small as 0.2 to 10 μm, and the fine content contained in the waste paper pulp. Resin pitch and synthetic pitch are adsorbed and removed out of the system in the selection process. Furthermore, when calcium sulfate remaining in such a system is used, pitch troubles due to resin agglomeration are prevented, printing equipment is hardly contaminated, and newsprint is produced at low cost and high operability. In addition, there is an advantage that the opacity and excellent paper strength equal to or higher than those of the conventional art are imparted to the newsprint, and the back-through and paper breakage are reduced.

  The amount of calcium sulfate remaining in the system can be appropriately adjusted depending on, for example, the disaggregation treatment conditions with a high-concentration pulper and the removal efficiency in the rough selection process.

  In the present invention, regarding calcium sulfate composed of gypsum derived from waste paper from gypsum board, by adjusting the volume average particle diameter in the differential curve of the particle size distribution by the Coulter counter method to 0.2 to 10 μm, There is also an advantage that wear can be further suppressed.

  Examples of the filler used in the present invention include calcium carbonate such as heavy calcium carbonate and light calcium carbonate, talc, kaolin clay, and delaminator, which are usually used as an internal filler for newsprint, in addition to the calcium sulfate. At least one selected from clays such as ted clay, inorganic fillers such as titanium dioxide, synthetic silica, and aluminum hydroxide, synthetic polymer fine particles such as polystyrene resin and urea formaldehyde resin, and the like can be used in combination as appropriate.

  The blending amount of the filler containing at least calcium sulfate is not particularly limited, but if it is too small, there is a possibility that the effect of suppressing pitch due to the filler, particularly calcium sulfate, may not be sufficiently expressed. Further, it is preferable to adjust to 4% by mass or more, and if it is too much, there is a risk that the paper strength of the newsprint will be reduced, so that the paper ash content is 15% by mass or less, and further 13% by mass or less. It is preferable to adjust so that it becomes.

  Furthermore, in the present invention, the pulp slurry obtained by internally adding a filler to the pulp, for example, a paper strength enhancer such as starches, vegetable gums, aqueous cellulose derivatives, sodium silicate; rosin, starch, carboxymethylcellulose, For internal paper sizing agents such as polyvinyl alcohol, alkyl ketene dimer, alkenyl succinic anhydride, and neutral rosin; yield improvers such as polyacrylamide and copolymers thereof, sodium silicate; pigments such as dyes and pigments Additives to be used can be appropriately blended within a range not impairing the object of the present invention.

  A pulp slurry is prepared from the pulp and filler, and additives as required, and the paper is made with a normal paper machine such as a twin wire type paper machine or a long net type paper machine after adjusting conditions such as pH. Thus, newsprint can be manufactured.

  The pH at the time of papermaking is such that aluminum sulfate (sulfuric acid band) is added and the resin component is fixed to the fiber via aluminum, or an aggregate of the resin component is formed and the resin component is taken into the paper support. Thus, in order to prevent adhesion of the resin component in the production process, it is general that the cationicity of the aluminum ion species is in the range of pH 4 or more and less than 6, which is the most active. However, since the waste paper pulp derived from the gypsum board waste paper used in the present invention is conventionally produced through the same waste paper treatment process, for example, the pH is as high as 6 or more, while considering the stability and pH adjustment due to the high pH. For example, when supplementary calcium carbonate is used, in addition to the viewpoint that the calcium carbonate dissolves and the yield is reduced, or the possibility of causing stains in the papermaking process is eliminated, the addition of sulfuric acid bands and dilute sulfuric acid to the fiber Since the deterioration can be prevented, the paper strength is adjusted to be about 6 to 9.5 from the viewpoint that paper strength is improved by making paper at pH 6 or higher than paper making at pH less than 6. Is preferred.

  In addition, calcium sulfate made of gypsum derived from waste paper from gypsum board is preferably incorporated in the pulp processing step including waste paper pulp, but can also be added to the pulp between the raw material blending chest and the inlet. By adding in the meantime, calcium sulfate made of gypsum derived from used gypsum board waste paper is easily dispersed, and the fixability to pulp fibers is improved. As a result, the yield of the entire filler is improved. Further, since the calcium sulfate does not inhibit the binding between the pulp fibers, the stiffness of the paper is not lowered. In order to disperse the calcium sulfate more uniformly and further improve the fixability to the pulp fiber, it is particularly preferable to add the calcium sulfate in the vicinity of the inlet as much as possible.

  Furthermore, in the present invention, a surface treatment agent containing, for example, starches such as starch and modified starch, and a polymer material such as polyvinyl alcohol and polyacrylamide is applied to the surface of newsprint obtained by making a pulp slurry. Also good.

  The modified starch is not particularly limited, and examples thereof include ordinary modified starch such as starch obtained by subjecting corn, potato, tapioca, wheat, rice and the like to oxidation treatment, enzyme treatment, and the like. In order to obtain a desired effect, the amount in the surface treatment agent when using the modified starch is preferably adjusted to be 40% by mass or more based on the total solid content.

  For the surface treatment agent, for example, latexes such as styrene-butadiene copolymer, pigments such as kaolin and calcium carbonate, antifoaming agents, water resistance agents, surface sizing agents, preservatives, and other various auxiliary agents may be added. it can. Moreover, there is no limitation in particular in solid content concentration of a surface treating agent, It is preferable to adjust to about 2-25 mass%, for example according to a coating device and a coating amount.

  If the surface treatment agent is used in an excessively large amount, not only the cost is increased, but also the adhesiveness of the paper surface called “Nepari” tends to be expressed when the surface of the newsprint is wet. If this Nepari property becomes large, blanket piling especially in a non-image area may be increased, or the paper surface may stick to the blanket during printing, and as a result, running troubles such as wrinkles and paper breakage may be caused. In addition, when the amount of the surface treatment agent used is too large, the transparency of the target newsprint increases, that is, the opacity may decrease or the ink drying property may decrease. Of the components contained in the surface treatment agent, starches and polyacrylamides are widely used because of their relatively low nepariness, but they are both highly soluble in water, so if they are included in too much, printing Sometimes it easily elutes in dampening water and deposits on the blanket with the filler, causing blanket piling. Also, the eluted surface treatment agent is transferred to and accumulated on the printing plate via the blanket, so that the non-image area of the printing plate becomes sensitized, and ink stains on the non-image area, that is, paper contamination called background contamination, is induced. Therefore, when using a surface treatment agent, it is preferable to adjust appropriately according to the components and the like so as not to become too much.

  The surface treatment agent is a coating apparatus commonly used in the papermaking field, such as a size press, a blade metering size press, a rod metalling size press, a gate roll coater, a blade coater, a bar coater, a rod coater, an air knife coater, etc. Can be applied to the surface.

The coating amount of the surface treatment agent is adjusted to 0.4 g / m ² or more, more preferably 0.7 g / m ² or more per side in terms of dry solid content, in order to sufficiently improve the surface strength of newspaper. In order not to increase the cost or to reduce the opacity of the newspaper and the ink drying property, the dry solid content is 3.0 g / m ² or less per side, and further 2.5 g. it is preferable to adjust / m ² as to become less.

  In the present invention, newspaper paper after paper making or newsprint paper coated with a surface treatment agent can be finished by passing through a calender device and applying pressure and smoothing as necessary. As the calendering device, a machine calender with a combination of a normal metal roll and a metal roll may be used, but the paper layer is more strongly pressed by using a soft calender with a combination of a metal roll and a resin roll. It is more preferable because it can be smoothed without further reducing the decrease in paper layer strength.

  In addition, in the use of the soft calendar, by passing the paper so that the back side, which is the rough side of the newspaper, comes into contact with the metal roll surface of the soft calendar first, it is possible to further improve the flatness and bulkiness, For example, in high-speed papermaking at 1500 m / min or more, it is possible to obtain newsprint with high flatness and little difference between the front and the back. Furthermore, with respect to the coating amount of the surface treating agent, by increasing the back surface side rather than the front surface side, better flatness and bulkiness can be obtained, and a firm newsprint can be obtained.

  The ash content of the newsprint thus obtained is 3% or more as measured according to the method described in JIS P 8128 “Method for testing ash content of paper and paperboard”, considering the neutralization of the newsprint. Is preferably 5% or more, and conversely, if there is too much ash, for example, the quality of the printing surface may be deteriorated in offset printing, or paper breakage may easily occur in the paper making process or the printing process. % Or less, more preferably 13% or less.

  In addition, if the amount of calcium sulfate used as a filler in the ash is too small, the effect of suppressing the resin pitch or synthetic pitch may not be sufficiently exhibited, so the proportion of calcium sulfate in the ash is 3% by mass. % Or more, preferably 5% by mass or more, and conversely, if the amount of calcium sulfate is too large, the ratio of calcium sulfate in the ash content may be contaminated by sulfate reduction. Is preferably 50% by mass or less, more preferably 45% by mass or less.

The basis weight of the newsprint of the present invention is the same as the method described in JIS P 8124 “Paper and paperboard—basis weight measurement method” in terms of weight reduction, for example, securing of paper quality strength in high-speed rotary printing and securing of printing opacity. It is preferably measured in accordance with 37 g / m ² or more, more preferably 40 g / m ² or more, and 48 g / m ² or less, further 46 g / m ² from the viewpoint of weight saving and resource saving in recent years. It is preferably ² or less.

  The whiteness of the newsprint is described in JIS P 8148 “Paper, paperboard and pulp—Method of measuring ISO whiteness (diffuse blue light reflectance)” in order not to cause eye strain of subscribers. Measured according to the method, it is preferably 50% or more, more preferably 52 to 56%, particularly preferably 53 to 55%.

  The newsprint of the present invention is required to have high opacity from the point of being difficult to see through during printing. It is preferably 88 to 95%, more preferably 90 to 94%, as measured in accordance with the method described in 53 “Opacity Test Method by Diffuse Lighting Method of Paper and Paperboard (Paper Backing)”.

In addition, the density of the newsprint of the present invention is measured in accordance with the method described in JIS P 8118 “Testing methods for thickness and density” from the viewpoint of maintaining the strength associated with the recent weight reduction and weight reduction. and, 0.55~0.60g / cm ^3, preferably further is 0.56~0.59g / cm ^3.

The stiffness (MD direction) of newsprint is measured in accordance with the method described in JIS P 8143, “Stiffness Test Method Using Paper Clark Stiffness Tester”, because it is suitable for high-speed rotary printing. And it is preferable that it is 30-55 cm < ³ > / 100, Furthermore, it is 32-50 cm < ³ > / 100.

  Here, in offset rotary printing performed using newspaper, dampening water and printing ink are supplied to the printing plate, and then the ink is transferred to a rubber plate called a blanket, and then transferred to paper for printing. Compared to conventional letterpress printing, this method uses relatively high viscosity ink, so that the ink does not penetrate into the paper layer, has good ink fillability, and has an ink penetration after printing. There is an advantage that there is little (the printing opacity is large).

  Furthermore, in recent years, with the colorization and weight reduction of newsprint, there is a further demand for good ink fillability and printing opacity. Among these, in order to improve ink fillability, a method of improving the smoothness of newsprint paper by flattening using a soft calendar as described above is widely adopted. However, if the nip pressure is increased in the calendar process or if the smoothing process is performed by increasing the number of nips, the ink fillability will be improved, but the bulk of the paper will be impaired, so the printing opacity and stiffness will decrease. There is a possibility that it may cause trouble of running failure such as generation of wrinkles during printing.

  On the other hand, if calendering is reduced, a bulky paper can be obtained, but the difference in front and back of the ink inking property increases, and the ink inking property decreases particularly on the paper surface with low smoothness. There is a risk that the density of the image is significantly different. This is because the dehydration conditions in the wire part and press part are slightly different between the front and back sides during the paper making process, resulting in differences in the smoothness of the paper, and the filler and fine fibers in the thickness direction. It is considered that this is caused by a difference in the front and back of the ink transferability due to the difference in the distribution state of the ink.

From the above, in the newsprint with basis weight preferably 37 to 48 g / m ² according to JIS P 8124 like the newsprint of the present invention, the relationship between the dampening water and the transfer of the printing ink. In consideration of the above, the newspaper paper has a 10-second Cobb water absorption (size) measured in accordance with the method described in JIS P 8140 “Paper and paperboard—Water absorption test method—Cobb method” of 30 to 300 g / m. ² and more preferably 50 to 280 g / m ² , and the oil absorption measured according to the method described in JIS P 3001 “Newspaper Roll” is 50 to 150 seconds, more preferably 70 to 140 seconds. . In this way, by adjusting the relationship between so-called hydrophilicity and oleophilicity within a predetermined range, it is possible to improve offset rotary printing suitability in combination with the flattening treatment.

  Also, the surface strength of the newsprint is preferably at least grade 3 or higher as measured by the RI tester described later, taking into account the paper quality in high-speed rotary printing.

Furthermore, in the newsprint of the present invention, as described above, since at least calcium sulfate is contained as a filler internally added to the pulp, the pitch number is 10 pieces / m ² or less, further 6 pieces / m ² or less. As described above, the generation of the pitch is sufficiently suppressed. In the present specification, the “pitch” refers to an adhesive foreign material such as a resin pitch or a synthetic pitch and having a size of 0.05 to 0.5 mm ² .

  As described above, the newsprint of the present invention is one in which the pulp contains at least waste paper pulp derived from used gypsum board waste paper and at least calcium sulfate as a filler. Therefore, the newsprint of the present invention can be manufactured at low cost by reusing resources, not only is excellent paper strength maintained and there is no paper break, but also blanket stains due to pitch and paper dust, clogging of the sword tip There is no color misregistration, printing white spots, etc., and high opacity and little show-through. Moreover, the newsprint of the present invention is excellent in various characteristics during printing, particularly color printing, and can be suitably used for high-speed rotary offset color printing such as about 1 to 170,000 copies / hour.

  Next, the newspaper of the present invention will be described in more detail based on the following examples, but the present invention is not limited to these examples.

Production Examples 1-12 and Comparative Production Examples 1-2 (Manufacture of waste paper pulp and preparation of calcium sulfate)
The used paper raw materials shown in Table 1 were subjected to a used paper processing process including a disaggregation process, a rough selection process, a deinking process, a fine selection process, a dehydration concentration process, and a bleaching process to produce used paper pulp.

  In the coarse selection step, a combination of a hole screen having a hole diameter shown in Table 1 and a slit screen having a slit width shown in Table 1 is used to select excessive calcium sulfate or calcium sulfate fixed to pulp fibers. did. In the deinking step, bubbles having the diameters shown in Table 1 were generated to perform flotation, and unnecessary gypsum was discharged out of the system.

  The operability at the time of waste paper pulp production and the quality stability of the waste paper pulp were evaluated as follows. The results are shown in Table 1.

[Operability]
The dewatering efficiency, productivity, and electric power necessary for pulverization of the waste paper raw materials were investigated and evaluated in four stages, and comprehensively evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: All were highly evaluated and well-balanced.
○: The evaluation may be averaged.
Δ: There was a problem in any of dehydration efficiency, productivity and electric power.
X: Actual operation was difficult.

[Quality stability]
The whiteness, color tone (Lab color system b value), contaminants and deinking properties of waste paper pulp were examined and evaluated in four stages, and evaluated comprehensively based on the following evaluation criteria. The whiteness was measured by the same method as the whiteness of newsprint described later.
(Evaluation criteria)
A: The whiteness was 57% or more, the b value was 6.5 or more, there was little to no impurities, and the deinking property was good.
○: Whiteness was 55% or more and less than 57%, b value was 6.0 or more and less than 6.5, there were few impurities, and there was no problem with deinking property.
Δ: At least the whiteness was less than 55%, the b value was less than 6.0, or there were many impurities.
X: The whiteness was less than 55%, the b value was less than 6.0, there were many impurities, and there was a problem in deinking properties.

  Further, the volume average particle diameter of calcium sulfate obtained in the waste paper treatment process was measured by the following method. The results are also shown in Table 1.

[Volume average particle diameter of calcium sulfate]
A calcium sulfate sample (10 mg) was added to 8 mL of a methanol solution, and dispersed with an ultrasonic disperser (output: 80 W) for 3 minutes. About this dispersion solution, the volume average particle diameter of calcium sulfate was measured with a Coulter counter particle size distribution measuring apparatus (TA-II type, manufactured by COULTER ELECTRONICS) using an aperture of 50 μm. However, for the 50 μm aperture that could not be measured, a 200 μm aperture was used. As the electrolytic solution, 0.7% high-purity NaCl aqueous solution (trade name: ISOTON II, manufactured by COULTER ELECTRONICS) was used.

Examples 1-12 and Comparative Examples 1-2 (production of newsprint)
In the ratio shown in Table 2, the waste paper pulp and mechanical pulp (TMP) obtained in Production Examples 1 to 12 and Comparative Production Examples 1 and 2 were blended, and Canadian Standard Freeness (CSF, JIS P 8121 “Pulp” The pulp slurry was adjusted to 120 mL in accordance with the “freeness test method”. To this pulp slurry, 0.5 parts by mass of cationized starch is added per 100 parts by mass of absolutely dry pulp, and the calcium sulfate obtained in Production Examples 1 to 12 and Comparative Production Examples 1 and 2 is used as a filler. It added so that it might contain in the ratio shown in Table 2, and after adjusting pH to about 7.6 with a sulfuric acid band, it made paper with the twin wire type paper machine. Further, oxidized starch (solid content concentration: about 2 to 15% by mass) as a surface treatment agent was applied with a gate roll coater so that the coating amount per one side was the amount shown in Table 2 in terms of dry solid content, Newspaper was obtained after drying.

  In addition, the ratio of each pulp was measured based on the method described in JIS P 8120 “Paper, paperboard and pulp-fiber composition test method”.

  Each physical property of the obtained newspaper was measured by the following method. These results are shown in Table 3.

(A) Basis weight Measured according to the method described in JIS P 8124 "Paper and paperboard-Basis weight measurement method".

(B) Density Measured according to the method described in JIS P 8118 “Paper and paperboard—Test method for thickness and density”.

(C) Hot water extraction pH
It was measured according to the method described in JIS P 8133 “Testing method for pH of paper, paperboard and pulp-water extract”.

(D) Ash content The ash content was measured according to the method described in JIS P 8128 “Method for testing ash content of paper and paperboard”.

(E) Cobb water absorption (size)
Based on the method described in JIS P 8140 “Paper and paperboard—Water absorption test method—Cobb method”, the measurement was performed at a measurement time of 10 seconds.

(F) Oil Absorbance Measured according to the method described in JIS P 3001 “Newspaper web”.

(G) Whiteness Measured according to the method described in JIS P 8148 “Paper, paperboard and pulp—Measurement method of ISO whiteness (diffuse blue light reflectance)”.

(H) Blank paper opacity TAPPI No. 53, measured according to the method described in "Opacity test method for paper and paperboard by diffuse illumination method (paper backing)".

(I) Stiffness (MD direction)
The measurement was performed in accordance with the method described in JIS P 8143, “Method for testing stiffness with a paper Clark stiffness tester”.

(J) Surface Strength After a newspaper sample was passed twice through a calendar made of a metal roll in a laboratory at a linear pressure of 40 kg / cm, an RI tester (model number: RI-2 printing) was applied to the surface of the newspaper sample. Printing was performed using an ink tack 6 (manufactured by Toyo Ink Manufacturing Co., Ltd.) with an aptitude test machine (manufactured by Ishikawajima Industrial Machinery Co., Ltd.). The state where the fibers per 10 cm ² were peeled off was visually observed and evaluated based on the following evaluation criteria (grade).
(Evaluation criteria)
1: There is considerable peeling of the fiber.
2: There is fiber peeling.
3: There is some peeling of the fiber.
4: There is little peeling of the fiber.
5: Almost no fiber peeling.
Of the evaluation criteria, it is determined that grade 3 or higher is actually usable.

  Next, each characteristic was investigated about the newsprint of Examples 1-12 and Comparative Examples 1-4 based on the following test examples 1-10. The results are shown in Table 4.

Test Example 1 (Still standing)
Using an RI printing suitability tester (manufactured by Akira Seisakusho Co., Ltd.), the newspaper paper surface was repeatedly printed five times with the rubber roll not applied with the test ink. Using a loupe, the surface of the paper web was visually observed in the range of 100 mm × 100 mm, and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: Very little standing
○: Little standing.
(Triangle | delta): There is a little bit of standing.
×: There are very many standing spots.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test example 2 (ink absorption unevenness)
Using an offset color printer (model number: SYSTEM C-20, manufactured by Komori Corporation), four-color printing was performed in the order of indigo, red, yellow, and black at a printing speed of 160,000 copies / hour. The ink density unevenness of the deep blue / red color portion was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: Ink density unevenness is not recognized at all, and the image is uniform and clear.
○: Ink density unevenness is hardly recognized, and the image is uniform.
Δ: Ink density unevenness is recognized and the image is slightly non-uniform.
X: Ink density unevenness is obvious and the image is non-uniform.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test Example 3 (Paper powder accumulation on blanket)
(1) Visual evaluation Using the same offset color printer as in Test Example 2, four-color printing was performed in the order of indigo, red, yellow, and black at the same printing speed. After printing 10,000 copies, the degree of paper powder accumulation on the blanket non-image area was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: Generation of paper dust is not recognized.
○: Slight generation of paper dust is observed, but there is no practical problem.
Δ: The occurrence of paper dust is clearly recognized.
X: A lot of paper dust is accumulated on the blanket, and the blanket is white.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

(2) Amount of paper powder Using an offset rotary press (Toshiba offset rotary press, manufactured by Toshiba Corporation), black monochrome printing was performed at a printing speed of 900 rpm. After printing 60,000 copies, the paper dust deposited on the blanket was scraped off, and the mass was measured and expressed as the mass per 100 cm ² . The film thickness of the fountain solution was 0.9 μm.

Test Example 4 (Printing Opacity)
Using the same RI printing suitability testing machine as in Test Example 1, printing was performed while changing the ink amount of black ink. The ratio of the back surface reflectance after printing with respect to the back surface reflectance before printing (the reflectance of the surface opposite to the printing surface) when the reflectance of the printed surface was 10% was determined based on the following formula. A spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd.) was used for the reflectance measurement.
Printing opacity (%) = (back surface reflectance after printing / back surface reflectance before printing) × 100

Test Example 5 (Printed white spot)
Using the same offset color printing machine as in Test Example 2, single-color printing of offset rotary printing ink (black) was performed at a dot area ratio of 30 to 100%. About a solid part with a halftone dot area ratio of 100%, the degree of white spots on the printed surface was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: Almost no white spots are observed.
○: Little white spots are observed.
Δ: White spots are observed.
X: White spots are remarkable.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test Example 6 (Nepari property)
Two newspaper paper samples were cut to an appropriate size and immersed in water for 10 seconds, and then the two sheets were quickly brought into close contact and passed through a calendar at a linear pressure of 100 kg / cm. After drying at room temperature for 24 hours, the peel strength of the two sheets was measured using a tensile tester (model number: Autograph AGS-500NG, manufactured by Shimadzu Corporation). In addition, the larger the numerical value, the higher the neppari property (adhesiveness).

Test Example 7 (Ink drying property)
Using the same offset color printing machine as in Test Example 2, four-color printing was performed in the order of indigo, red, yellow, and black with newspaper printing ink having a vegetable oil content of 45% at the same printing speed. Overlap the 500 copies of the printed material so that the printed surface and the white paper surface overlap, and leave it for 1 day under a load of 5 kgf (about 49 N), and then visually observe the degree of dirt on the white paper surface based on the following evaluation criteria: And evaluated.
(Evaluation criteria)
(Double-circle): Dirt is hardly recognized.
○: Only a small amount of dirt is observed.
Δ: Dirt is observed.
X: Dirt is remarkable.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test Example 8 (Number of paper breaks)
Using an offset rotary press (Toshiba offset rotary press, manufactured by Toshiba Corporation), black monochrome printing was performed at a printing speed of 900 rpm, and the number of occurrences of sheet breakage was measured during 60,000 copies.

Test Example 9 (Pitch number)
The number of pitches (size: 0.05 to 0.50 mm ² ) contained in 1 m ^{2 of} newspaper was visually counted using a foreign matter measurement chart manufactured by the National Printing Bureau.

Test Example 10 (Back-through)
Using the same web offset press as in Test Example 8, black single color printing was performed at the same printing speed. After printing 60,000 copies, the black solid surface was visually observed from the back side and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: Almost no see-through is observed.
○: Only a small amount of strikethrough is recognized.
(Triangle | delta): See-through is recognized.
X: The showthrough is remarkable.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

  From the results shown in Table 4, since all the newsprints of Examples 1 to 12 were obtained by internally adding calcium sulfate as a filler to pulp containing waste paper pulp derived from gypsum board waste paper, Since there is little paper dust generation, there is no or almost no blanket stains, there are also few white spots on printing, excellent ink absorption and ink drying properties, high opacity, little show-through, and no paper breaks In particular, it can be seen that it has characteristics suitable for high-speed offset rotary printing.

  On the other hand, the newspapers of Comparative Examples 1 and 2 do not use waste paper pulp derived from waste gypsum board paper, and because of the large number of pitches and generation of paper dust, blanket stains are remarkable, printing white spots, ink It can be seen that there are problems with the absorptivity, ink drying, back-through, and paper breakage, which are inappropriate for high-speed offset rotary printing, for example.

  The newsprint of the present invention can be suitably used for high-speed offset printing such as high-speed offset rotary color printing of about 1 to 170,000 copies / hour, for example.

Claims (5)

Newspaper paper with filler added to pulp,
The pulp contains at least waste paper pulp derived from waste gypsum board paper,
Newsprint paper comprising at least calcium sulfate as the filler.   The newsprint according to claim 1, wherein the calcium sulfate is made of gypsum derived from waste paper on gypsum board.   The newsprint according to claim 1, wherein the ash content according to JIS P 8128 is 3 to 15%, and the proportion of calcium sulfate in the ash content is 3 to 50% by mass.   Waste paper pulp derived from waste gypsum board waste paper is obtained by using waste paper raw materials containing gypsum board waste paper at least in the waste paper treatment process including the disaggregation process, the rough selection process, the deinking process, the fine selection process, the dehydration concentration process, and the bleaching process. The newsprint according to claim 1, wherein The newsprint according to claim 1, wherein the number of pitches is 10 pieces / m ² or less.