JP2006016716A - Method for producing neutral newsprint paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing neutral newsprint paper, capable of greatly improving a yield on wires of a finely divided component, such as a finely divided pulp fiber in paper stock, a finely divided material derived from waste paper, and a loading material, capable of continuously conducting paper making for a long period, and capable of giving good formation, when the paper making of the newsprint paper is conducted through a neutral paper-making process with a twin-wire paper-making machine, especially when a paper-making speed of the twin-wire paper-making machine is high, and more especially when the paper making of the neutral newsprint paper having a high content of a loading material in the paper is conducted. <P>SOLUTION: This method for producing the neutral newsprint paper through the neutral paper-making process with the twin-wire paper-making machine comprises adding an emulsion-type cationic polyacrylamide-based substance which has a weight-average molecular weight of ≥15,000,000, when measured by an intrinsic viscosity procedure, to the paper stock as a yield-improving agent, so as to conduct the paper making of the neutral newsprint paper. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing neutral newsprint paper, and more specifically, a high yield of paper and ash in a papermaking process for producing newsprint paper by a neutral papermaking method on a twin wire paper machine, and The present invention relates to a method for producing neutral newspaper printing paper having good formation.

  Improving the yield of paper and ash on the wire in the papermaking process can be achieved by reducing the drainage load, reducing manufacturing costs by reducing lost materials, improving paper quality, such as improving paper duality, and improving productivity. It has an important meaning.

For this reason, various yield improvement systems have been proposed so far, and examples include the following systems.
(1) Method of adding one solution of cationic or anionic polyacrylamide
(2) Method of adding cationic or anionic polyacrylamide after addition of cationic polyelectrolyte
(3) Method of adding colloidal silica after adding cationic or amphoteric polymer substance
(4) Method of adding bentonite after adding cationic polymer substance

  One of the recent technological trends in the manufacture of newspaper printing paper is the increase in the ratio of used paper to newspaper printing paper against the background of increased environmental awareness and cost reduction. The ratio of used paper is increasing year by year, and it is not uncommon for newspaper printing paper to exceed 70%. Waste paper contains a large amount of negatively charged fine particles such as ink components and paint components derived from coated paper. Although efforts have been made to remove these ink components and paint components by washing and separation processes in the used paper manufacturing process, the ink components and paint components flow into the papermaking system without being completely removed. Negatively charged particles repel each other, do not easily bind to the negatively charged pulp fibers in the raw material, and the ink and paint components that have passed through the paper machine wire accumulate in the papermaking system. become. When the concentration of the negatively charged colloidal particles increases in this way, there is a problem that the effect of the yield improver added in the papermaking system is remarkably reduced.

  In the production of newspaper printing paper, paper machines are increasing in size and speed from the viewpoint of improving production efficiency. Currently, the maximum papermaking speed of newspaper machines has reached over 1,500 m / min. As the speed of the paper machine increases, the shearing force applied to the stock slurry increases. The flocs once formed by the yield improver added to the paper stock are easily broken by this strong shearing force, and there is a problem that the effect of the yield improver is significantly reduced.

  Furthermore, in order to improve the front / back difference (two-sidedness) of the paper quality of newspaper printing paper, the paper machine wire part is being switched from the conventional long net paper machine to the twin wire system. This twin wire also reduces the effect of the yield improver. Many of the recent new newspaper machines have adopted a method in which the stock is sprayed directly between two wires from the stock inlet, such as a gap former among twin wire methods. In this method, since the dehydration is performed simultaneously with the paper layer formation, the yield is extremely reduced.

  Further, as a major change in the papermaking method of newspaper printing paper, it can be mentioned that newspaper printing papermaking is changing from acidic papermaking to neutral papermaking. The purpose of adding filler to paper is to make the paper dense and improve opacity, smoothness, printability, etc., but talc is commonly used as a filler in conventional newspaper printing paper made with acid paper In particular, amorphous silica such as white carbon having a high oil absorption has been used in combination in order to suppress print-through. Since talc and white carbon are stable substances in the acidic region, it is possible to use a lot of sulfuric acid bands. By adding this inorganic coagulant sulfate band and synthetic polymer-based yield improver, newspaper printing paper can be used. In acidic papermaking, the yield of fine particles such as fine pulp fibers in paper stock, fine particles derived from waste paper, and fillers was maintained at a level with no problem. In the neutral papermaking method, it is common to add at least calcium carbonate as a filler, but this calcium carbonate reacts with the sulfate band to form calcium sulfate, which precipitates in the papermaking system and causes contamination within the system. This may cause paper defects such as holes and holes, and cause paper breaks. Therefore, in the neutral papermaking method, the use amount of the sulfuric acid band is limited, and there is a problem that the yield of fine particles in the paper is reduced accordingly.

  Furthermore, there is a trend to increase the amount of filler in the neutral newsprint paper for the purpose of improving the quality such as high whiteness, high opacity, and reduced print back-through. Since talc, which is a filler used in the acid papermaking method, and white carbon that forms aggregated secondary particles have a large particle size, if these are mixed in a large amount of acid newspaper printing paper, these fillers will become paper. There is a problem that the amount of paper dust increases when the newspaper is printed. For this reason, there is a limit to the amount of talc or white carbon. Calcium carbonate used as a filler in the neutral papermaking method is available in many types with a small particle size, and small particle size calcium carbonate can be released from the paper even when incorporated in large amounts in the paper. There are few features. Since calcium carbonate can provide paper with excellent functions in terms of quality such as high whiteness, high opacity, and high opacity after printing, high blending of calcium carbonate is being promoted. However, the small particle size calcium carbonate has a problem that the yield to paper is reduced in the paper making process.

  As mentioned above, when making newsprint paper with the twin-wire paper machine by the neutral paper-making method, especially when the paper-making speed of the twin-wire paper machine is high, and among these, the medium has a high filler content. When paper is produced, the yield of fine components such as fine pulp fibers in paper stock, fine particles derived from waste paper, and fillers on the wire is lowered.

  For this reason, a one-part solution containing a cationic or anionic polyacrylamide type yield improver having a weight average molecular weight of about 10 million at the maximum by the intrinsic viscosity method conventionally used as a yield improver in newspaper printing paper making. In the case of maintaining the formation of neutral newspaper printing paper in a two-liquid yield formulation in which the above-mentioned cationic or anionic polyacrylamide-based yield improver is added after the addition of a cationic polyelectrolyte, or a yield formulation, A sufficient yield of fine components could not be obtained. Due to this decrease in yield, the concentration of fine components contained in white water that has passed through the wire has increased, and the load on white water treatment equipment such as polydisc filters and flotation separators has increased, resulting in a situation where white water cannot be treated. there were. In addition, as a result of the gradual accumulation of fine components that have passed through the wire in the stock, the solids concentration of the stock supplied to the paper machine stock inlet becomes gradually higher, making the paper unstable, and in the worst case, finally the paper Occasionally, it became impossible. The economic loss due to these paper interruptions is very large, and it has become a very serious problem in making newsprint paper by the neutral papermaking method. In addition, white water discharged as wastewater outside the papermaking system contains a large amount of fine particles, which are valuable resources, and there is a problem that this economic loss is large and the load on the wastewater treatment facility is further increased. .

  If the yield improver is added at a high rate in the one-liquid yield formulation or the two-liquid yield formulation, the yield of fine particles is improved to some extent, but the yield improvement reaches a peak, so that a satisfactory yield cannot be obtained, and the papermaking still remains. There is a problem that the neutral newspaper printing paper obtained by making paper is unstable and the formation is deteriorated.

  Techniques have been proposed to improve the yield of fine components when making newsprint paper by neutral papermaking. For example, in the case where newspaper printing paper is made from neutral to weakly alkaline paper using a papermaking raw material containing a filler mainly composed of calcium carbonate, the polymerized cationic water-soluble polymer and / or polycondensation type cation is used as the papermaking raw material. A method of making paper by adding an anionic water-soluble polymer after adding a functional substance is disclosed (see Patent Document 1). In addition, a pulp containing 30 to 100% by weight of mechanical pulp and / or deinked pulp for the purpose of improving the yield and drainage in neutral to alkaline papermaking containing a large amount of mechanical pulp and / or deinked pulp Disclosed is a technology in which a cationic polyelectrolyte, an anionic polymer substance and bentonite are added in this order to a paper material having a solid content concentration of 0.1 to 1.5% by weight and a pH of 6 to 10 comprising a filler and a filler. (See Patent Document 2). In addition, mechanical pulp and / or deinked pulp is used as a total pulp component for the purpose of improving the yield and drainage when making a paper system containing a large amount of mechanical pulp and / or deinked pulp in the neutral to alkaline region. Containing 30 to 100% by weight of pulp and filler, solid content of 0.1 to 1.5% by weight, and pH = 6 to 10 paper, cationic coagulant, phenolic compound, nonion A technique is disclosed in which the coagulant is added in this order and the ratio of the cationic coagulant to the phenolic compound ranges from 25:75 to 75:25 (see Patent Document 3). Although these techniques slightly improve the yield of fine components when making neutral newspaper printing paper, it is still not a sufficient effect.

JP 2002-227093 A Japanese Patent Laid-Open No. 9-250095 Japanese Patent Laid-Open No. 11-247089

  Based on the above situation, when making newsprint paper with the twin-wire paper machine by the neutral paper-making method, the twin-wire paper machine has a high paper-making speed, and among these, the medium has a high filler content. In order to make stable long-term continuous papermaking, the yield of fine components such as fine pulp fibers in paper stock, fine particles from waste paper, and fillers on the wire is greatly increased. There is a strong demand for early development of a yield technology that can improve the quality of the paper and maintain the good quality of the printed neutral newspaper.

  When making newspaper printing paper with a twin-wire paper machine by the neutral paper making method, especially when the paper speed of the twin-wire paper machine is high, among these, neutral newspaper printing paper with a high paper filling rate is used. When making paper, the yield of fine components such as fine pulp fibers in paper stock, fine particles derived from waste paper, and fillers on the wire can be greatly improved, long-term continuous paper making is possible, and the formation is good The present invention is to provide a method for producing a neutral newspaper printing paper.

  As a result of diligent research on yield improvement when making neutral newspaper printing paper with a twin-wire paper machine, the present inventors have found that there is no ultrahigh molecular weight emulsion type cationic polyacrylamide based material that has not been used as a yield improver. As a result, the inventors have found that the above-mentioned problems can be solved, and have completed the present invention. In other words, in the process of producing newsprint paper by the neutral paper making method on a twin-wire paper machine, an emulsion-type cationic polyacrylamide material with a weight average molecular weight of 15 million or more by the intrinsic viscosity method as a yield improver is used as the stock. The problem can be solved by adding and making neutral newspaper printing paper.

  When newspaper printing paper is made with a twin-wire paper machine using the neutral paper making method, by implementing the present invention, a high yield can be achieved while maintaining a good texture of the paper. Stable long-term continuous papermaking becomes possible. In particular, when the present invention is applied to the production of neutral newspaper printing paper having a high paper filling rate, the effect of the invention is great.

  When neutral newspaper printing paper is made with a twin-wire paper machine, the yield of fine particles is lowered, the operation becomes unstable, and the paper quality may be changed. Above all, when the paper making speed of the twin wire paper machine becomes high, this problem increases as the speed increases. Furthermore, among these, the yield reduction is a serious problem in the making of neutral newspaper printing paper having a high paper filler rate. In addition to the above problems, long-term continuous paper making is impossible in some cases. Accordingly, the paper machine to which the neutral newspaper printing paper manufacturing method of the present invention is applied is a twin-wire paper machine, preferably a twin-wire paper machine with a high paper-making speed, and more preferably a high filler content in the paper. This is a twin-wire paper machine with a high paper-making speed for making neutral newspaper printing paper. Examples of twin wire paper machines include gap formers and on-top formers. The high speed referred to in the present invention is 700 m / min or more, but the effect obtained by applying the present invention is preferably 800 m / min or more, more preferably 1,000 m / min or more because the effect is even higher. In addition, since it is expected that the newspaper machine will continue to increase in the future, the upper limit of the paper making speed is not set in the present invention.

  The pulp raw material of the neutral newsprint paper produced by the present invention is not particularly limited, and is used for newsprint paper such as mechanical pulp (MP), deinked pulp (DIP), and softwood kraft pulp (NKP). Any material generally used as a papermaking raw material may be used, and one or two or more of these may be used as appropriate. Examples of mechanical pulp include groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), chemiground pulp (CGP), and semi-chemical pulp (SCP). . The deinked pulp may be any deinked pulp made from high-quality paper, medium-quality paper, low-grade paper, newspaper, flyers, magazines, etc., or unselected waste paper mixed with these. Absent.

  The filler contained in the neutral newsprint produced by the present invention contains at least calcium carbonate or light calcium carbonate-silica composite. As the calcium carbonate, either heavy calcium carbonate or light calcium carbonate can be used, but light calcium carbonate is preferably used from the viewpoint of wire wear of a paper machine and the quality of neutral newspaper printing paper. Among the light calcium carbonates, it is more preferable that primary particles aggregate to form secondary particles. Among the light calcium carbonates in which primary particles are aggregated to form secondary particles, rosetta type light calcium carbonate is most preferable. Examples of the calcium carbonate-silica composite include composites described in Japanese Patent Application Laid-Open No. 2003-212539 and Japanese Patent Application No. 2004-27483. In addition to calcium carbonate and / or light calcium carbonate-silica composite, amorphous silica such as white carbon may be used in combination. The above calcium carbonate, light calcium carbonate-silica composite, and amorphous silica are added to the pulp raw material as a fresh filler, but in addition to this, the ash content from the deinked pulp remains in the wet paper, the result Work as a filler. The neutral filler printing paper to be described later is the sum of the fresh filler and the ash derived from the deinked pulp.

  The neutral newspaper printing paper produced in the present invention has a filler content in the paper of 1 to 40 solids by weight. In papermaking, the yield decreases as the filler content in the paper increases. Therefore, the effect of the present invention is greater when the present invention is applied to the production of neutral newspaper printing paper having a high paper filling rate. From this viewpoint, the filler content in the paper is preferably 10 to 40% by weight, more preferably 15 to 40% by weight. A fresh filler is added so as to obtain the filler content in the paper.

  As the internal additive, a dry paper strength enhancer such as polyacrylamide and cationized starch, and a wet paper strength enhancer such as polyamidoamine epichlorohydrin can be added. If necessary, a neutral sizing agent such as an alkyl ketene dimer, alkenyl succinic anhydride, or neutral rosin sizing agent may be internally added.

  The yield improver used in the production method of the present invention is an emulsion-type cationic polyacrylamide-based material having a weight average molecular weight of 15 million or more by the intrinsic viscosity method. Preferably, the weight average molecular weight is 20 million or more. This emulsion-type cationic polyacrylamide-based material is emulsion-polymerized by a known method, but is preferably synthesized by a water-in-oil type reverse-phase emulsion method. The specific composition is not particularly limited as long as the substance contains an acrylamide monomer unit as a structural unit. For example, a copolymer of quaternary ammonium salt of acrylate ester and acrylamide, or acrylamide And a quaternized ammonium salt after copolymerization of acrylate and acrylate. This ultrahigh molecular weight emulsion-type cationic polyacrylamide-based material has not been used as a yield improver in papermaking. The cationic charge density of the cationic polyacrylamide-based material is not particularly limited, but since the cation requirement of the stock for newspaper printing paper is extremely high, it is better that the cationic charge density is high from the viewpoint of increasing the yield. Is preferably 0.5 meq / g or more, more preferably 1.0 meq / g or more, still more preferably 1.5 meq / g or more, and most preferably 2.0 meq / g or more. The emulsion type cationic polyacrylamide material having a weight average molecular weight of 15 million or more can be appropriately selected from commercially available materials.

  For the purpose of increasing the yield, an inorganic coagulant such as a sulfuric acid band or polyaluminum chloride may be used in combination as long as the effects of the present invention are not impaired.

  In the paper machine pre-treatment process, a fresh filler is usually added in front of a fan pump to a paper stock obtained by mixing a pulp raw material and an internally added paper making chemical with a mixer, and then mixed uniformly. Therefore, the place of addition of the emulsion-type cationic polyacrylamide material having a weight average molecular weight of 15 million or more is between after the filler addition and before the paper machine stock inlet. When the cationic polyacrylamide material and the inorganic coagulant are used in combination, the inorganic coagulant is added after the mixer and before the addition of the cationic synthetic polymer material.

  The amount of the cationic polyacrylamide-based material added is appropriately determined according to the properties of the stock and the paper making speed, but cannot be generally specified, but is usually 50 to 750 ppm based on the weight of the solid content of the stock. 50 to 600 ppm is preferable, 100 to 600 ppm is more preferable, and 100 to 500 ppm is still more preferable. If the amount of the cationic polymer substance added is less than 50 ppm, the neutral newspaper printing paper is satisfactory, but a sufficient yield of fine components cannot be obtained, and instability of papermaking cannot be resolved. If it is added in excess of 750 ppm, the yield of fine components increases, but the formation deteriorates, and printing defects such as uneven printing due to uneven formation occur.

  Various dewatering elements and dewatering devices are arranged in the wire part of the twin wire paper machine. Specifically, foil blades, suction boxes and the like, and in the case of an on-top twin wire, an upper dewatering device and the like can be mentioned. Although the yield of fine fibers varies depending on the conditions of these dehydrating elements and dehydrating apparatuses, the type and arrangement of these dehydrating elements and dehydrating apparatuses are not particularly limited in the present invention, and are within the normal operating range. Thus, these dehydrating elements can be appropriately selected and arranged.

  Moreover, although a yield changes also with the kind of wire, there is no limitation in particular also about the wire opening or the weaving method of a wire, and it can select and use from commercially available wires suitably.

  There is no limitation on the press format of the paper machine press process, and a public apparatus can be used. Further, the pressing conditions are not particularly limited, and can be appropriately set within a normal operation range.

  The paper machine pre-dryer and after-dryer can also use a public apparatus, and the drying conditions are not particularly limited, and can be appropriately set within the normal operating range.

  The surface coating apparatus installed between the pre-dryer and the after-dryer may be a publicly-used one, and is not particularly limited. However, a gate roll size press is generally used in a newspaper machine, and also in the present invention. Preferably used. Using the surface coating apparatus, the surface treatment agent may be applied to the surface of the neutral newspaper printing paper base paper, or may be bypassed.

  When the surface treatment agent is applied to the surface of the neutral newspaper printing paper base paper, the composition of the surface treatment agent is not limited. Examples of water-soluble polymer adhesives intended to enhance surface strength include raw starch, oxidized starch, esterified starch, cationized starch, enzyme-modified starch, aldehyde-modified starch, hydroxyethylated starch, and hydroxypropylated starch. Modified starch, cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, modified alcohols such as polyvinyl alcohol, carboxyl modified polyvinyl alcohol, styrene butadiene copolymer, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl chloride , Polyvinylidene chloride, polyacrylic acid ester, polyacrylamide or the like alone or in combination. Among them, the application of hydroxyethylated starch or hydroxypropylated starch, which is excellent in the effect of improving surface strength, is most preferable. In addition to the above water-soluble polymer adhesive, general surface sizing agents such as styrene acrylic acid, styrene maleic acid, and olefin compounds may be applied in combination to impart water absorption resistance to the paper. However, it is preferable to apply a sizing agent whose ionicity is cationic.

  When a surface treatment agent comprising a water-soluble polymer adhesive and a surface sizing agent is applied, the mixing ratio of the water-soluble polymer adhesive and the surface sizing agent may be within a public range, and is not particularly limited. The amount of the water-soluble polymer adhesive and / or the surface sizing agent applied to the base paper may be within a public range, and is not particularly limited.

  There are no particular limitations on the type and processing conditions of the calendar device, and a public device such as a normal calendar made of metal rolls, a soft nip calender, or a high temperature soft nip calender is appropriately selected, and according to the quality target value of newspaper printing paper, What is necessary is just to set conditions within the controllable range of these apparatuses.

  The formation of the neutral newsprint paper produced by the production method of the present invention is the formation index (Paper Pulp Technology Times 28 (5), 1985, P30-35) by the laser light transmission fluctuation method, and is 11.0 or less. Preferably, it is preferably 10.5 or less. In addition, the smaller the value of the formation index is, the better the paper is. A difference of 0.5 in the formation index can be recognized as a difference in formation with the naked eye.

The neutral newspaper printing paper produced by the present invention is not limited for offset printing or letterpress printing. Moreover, although there is no limitation also about the basic weight of neutral newspaper printing paper, it is usually 36-50 g / m < ² >.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, naturally this invention is not limited to these. In the examples, “part” and “%” respectively represent “part by weight” and “% by weight” unless otherwise specified.

The method for measuring yield and paper formation is as follows.
[Measurement method of yield]
Solid stock concentration and ash concentration were measured for the stock inlet raw material and white water that had fallen under the wire (described as white water under the wire). Paper yield was measured by the following formula (1), and ash yield was measured by the following formula (2).
Paper yield = 100 x (A-B) / A ... Formula (1)
A: Solid content concentration of stock inlet raw material (g / l)
B: Solid content concentration under white wire (g / l)
Ash content yield = 100 x (C-D) / C ... Formula (2)
C: Ash content of stock inlet raw material (g / l)
D: Ash concentration of white water under wire (g / l)
Ash content measurement: The solid content of the stock inlet raw material and the white water under the wire was ashed at 525 ° C.
[Measurement method of paper texture]
The texture of the paper was evaluated by SHEET-FORMAION-TESTER (He-Ne laser light transmission fluctuation method) manufactured by Toyo Seiki Seisakusho.

[Neutral printing of neutral newspaper printing paper]
(1) Paper machine: Gap former paper machine. In the following examples and comparative examples, the type of wire used and the type and arrangement of the dehydrating elements were fixed.
(2) Pulp raw material composition: deinked pulp (freeness CSF = 240ml) 80%, mechanical pulp (freeness CSF = 120ml) 10%, softwood kraft pulp (freeness CSF = 600ml) 10%
(3) Filler ratio in paper: Rosetta-type light calcium carbonate (average particle size 2.5 μm) was added so that the filler ratio in paper was 15%.

[Example 1]
To the stock mixed with pulp and filler, an emulsion-type cationic polyacrylamide material (Samar Co., Ltd., Realizer R300, cationic charge density 1.96 meq / g) having a weight average molecular weight of 20 million by the intrinsic viscosity method, On the fan pump suction side, neutral newspaper printing paper was made at a paper making speed of 1,000 m / min, with 300 ppm added per solid weight. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Example 2]
A neutral newspaper printing paper was made in the same manner as in Example 1 except that the addition rate of the emulsion-type cationic polyacrylamide-based material in Example 1 was changed to 200 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Example 3]
A neutral newspaper printing paper was made in the same manner as in Example 1 except that the addition rate of the emulsion-type cationic polyacrylamide-based material in Example 1 was changed to 100 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Comparative Example 1]
A solution-type cationic polyacrylamide yield improver with a weight average molecular weight of 9 million by the intrinsic viscosity method (DR8500, manufactured by Hymo Co., Ltd., cationic charge density of 1.8 meq / g) is added to the paper stock mixed with pulp and filler. On the suction side of the fan pump, neutral newspaper printing paper was made at a paper making speed of 1,000 m / min with 400 ppm added per solid weight of the stock. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Comparative Example 2]
Neutral newsprint paper was made in the same manner as in Comparative Example 1 except that the addition rate of the yield improver in Comparative Example 1 was 200 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Example 4]
To the stock mixed with pulp and filler, an emulsion-type cationic polyacrylamide material (Samar Co., Ltd., Realizer R300, cationic charge density 1.96 meq / g) having a weight average molecular weight of 20 million by the intrinsic viscosity method, On the fan pump suction side, neutral newspaper printing paper was made at a paper-making speed of 1,300 m / min with 300 ppm of the solid content weight added. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Example 5]
A neutral newspaper printing paper was made in the same manner as in Example 4 except that the addition rate of the emulsion type cationic polyacrylamide-based material in Example 4 was changed to 200 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Example 6]
Neutral newspaper printing paper was made in the same manner as in Example 4 except that the addition rate of the emulsion-type cationic polyacrylamide material in Example 4 was changed to 100 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Comparative Example 3]
A solution-type cationic polyacrylamide yield improver with a weight average molecular weight of 9 million by the intrinsic viscosity method (DR8500, manufactured by Hymo Co., Ltd., cationic charge density of 1.8 meq / g) is added to the paper stock mixed with pulp and filler. On the fan pump suction side, neutral newspaper printing paper was made at a paper making speed of 1,300 m / min with 400 ppm added to the solid weight of the stock. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Comparative Example 4]
Neutral newsprint paper was made in the same manner as in Comparative Example 3 except that the addition rate of the yield improver in Comparative Example 3 was 200 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Example 7]
To the stock mixed with pulp and filler, an emulsion-type cationic polyacrylamide material (Samar Co., Ltd., Realizer R300, cationic charge density 1.96 meq / g) having a weight average molecular weight of 20 million by the intrinsic viscosity method, On the fan pump suction side, neutral newspaper printing paper was made at a paper making speed of 1,600 m / min with 300 ppm of the solid content of the stock added. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Example 8]
Neutral newspaper printing paper was made in the same manner as in Example 7 except that the addition rate of the emulsion type cationic polyacrylamide material of Example 7 was changed to 200 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Example 9]
A neutral newspaper printing paper was made in the same manner as in Example 7 except that the addition rate of the emulsion type cationic polyacrylamide-based material in Example 7 was changed to 100 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Comparative Example 5]
To the stock mixed with pulp and filler, a solution type cationic polyacrylamide yield improver with a weight average molecular weight of 9 million by the intrinsic viscosity method (made by Hymo Co., Ltd., DR8500 cationic charge density 1.8 meq / g), On the fan pump suction side, neutral newspaper printing paper was made at a paper making speed of 1,600 m / min with 400 ppm added to the solid weight of the stock. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

[Comparative Example 6]
A neutral newsprint was made in the same manner as in Comparative Example 5 except that the addition rate of the yield improver in Comparative Example 5 was changed to 200 ppm. The paper material yield and the ash content yield during paper making were measured, and the formation of the obtained neutral newsprint paper was measured. The results are shown in Table 1.

  From the comparison of Examples 1 to 3 and Comparative Examples 1 and 2 in which the papermaking speed is 1,000 m / min, the emulsion type cationic polyacrylamide-based material of the Examples has a higher stock yield and ash content than the yield improver of the Comparative Examples. It can be seen that the yield is excellent and that the neutral newspaper printing paper is well formed. Comparative Example 1 has a relatively good paper yield and ash yield, and long-term continuous papermaking is possible in this respect, but there is a problem that the formation of the obtained neutral newsprint paper deteriorates. In the case of Comparative Example 2, since the paper material yield and the ash content yield are too low, it is judged that long-term continuous papermaking is difficult. From the comparison of Examples 4 to 6 and Comparative Examples 3 and 4 where the papermaking speed is 1,300 m / min, the emulsion-type cationic polyacrylamide-based material of the Example has a higher paper yield and ash content than the yield improver of the Comparative Example. It can be seen that the yield is excellent and that the neutral newspaper printing paper is well formed. In the case of Comparative Examples 3 and 4, since the paper material yield and the ash content yield are too low, it is judged that long-term continuous papermaking is difficult. From the comparison of Examples 7 to 9 and Comparative Examples 5 and 6 where the papermaking speed is 1,600 m / min, the emulsion-type cationic polyacrylamide-based material of the Examples has a higher paper yield and ash content than the yield improver of the Comparative Examples. It can be seen that the yield is excellent and that the neutral newspaper printing paper is well formed. In the case of Comparative Examples 5 and 6, since the paper yield and the ash yield are too low, it is judged that long-term continuous papermaking is difficult.

By carrying out the present invention, it is possible to stably produce newspaper printing paper having a good formation by a neutral paper making method using a twin-wire paper machine, and to make continuous long-term paper making. Therefore, the effect of the present invention is extremely great.

Claims (3)

  This is a method for producing newsprint paper by a neutral papermaking method on a twin-wire paper machine, and an emulsion-type cationic polyacrylamide-based material with a weight average molecular weight of 15 million or more by an intrinsic viscosity method as a yield improver. A method for producing neutral newspaper printing paper, which comprises adding and making paper.   2. The method for producing neutral newspaper printing paper according to claim 1, wherein the paper making speed of the twin wire paper machine by the neutral paper making method is 700 m / min or more. 3. The method for producing neutral newspaper printing paper according to claim 1 or 2, wherein the formation index of the neutral newspaper printing paper is 11.0 or less according to the laser beam transmitted light fluctuation method.