JP6970707B2 - Newspaper - Google Patents

Description

The present invention relates to newspapers printed by an offset rotary press, and more particularly to neutrally made supple newspapers.

In recent years, offset printing papers, especially offset printing newspapers, are rapidly becoming color printing, speeding up, and towering, and along with this, even better color printing quality is achieved for newspapers, which are printing media. Printing workability is required. In addition, since mass printing is performed in a short time, problems such as blurring of the printed surface due to the accumulation of paper dust are also regarded as important. Further, in recent years, there has been an increasing demand for weight reduction of newspapers from the viewpoint of environmental protection, page increase, carrying, and the like. However, if the mass (basis weight) per unit area of the paper is reduced in order to reduce the weight, the paper becomes thinner, and the opacity and the paper strength of the paper may decrease. As a result, deterioration of print quality such as "through-through" in which the image or characters on the front surface of the print can be seen through on the back surface and deterioration of the sharpness of the printed image may occur.

On the other hand, newspaper paper that reads articles with the paper unfolded and turns pages requires suppleness and ease of turning when turning pages. Newspaper with high rigidity and tension has good processing suitability such as folding after printing, but it is stiff when reading newspapers, so it is difficult to turn pages. Therefore, there is also a demand for the development of newspaper paper that is supple and easy to turn while having a paper stiffness that does not impair workability during printing.

As a method for reducing strike-through of newspaper paper, for example, it is known that increasing the opacity, specific scattering coefficient, and oil absorption of the paper is effective.

As a technique for increasing opacity, the compounding ratio of used paper pulp is 60% by mass or more, 3 to 25% by mass of one or more fillers containing fresh calcium carbonate is added, and 1.5 to 4.0 g on both sides. A newspaper paper having a pigment coating layer of / m ² and an ash content of 7 to 25% by weight derived from the base paper and the pigment coating layer (Patent Document 1), polyhydric alcohols, and ester compounds of fatty acids (Patent Document 1). The melting point selected from A) and the ester compound (B) which is an ester compound of polyhydric alcohol and fatty acid and has an oxyalkylene group having 2 to 4 carbon atoms having an average of more than 0 mol and less than 12 mol per mol of the ester compound. A method (Patent Document 2) has been proposed in which a bulking agent such as an ester compound having a temperature of 100 ° C. or lower is added to increase the bulk of the paper and provide a highly opaque newspaper.

As a technique for increasing the specific scattering coefficient, a method of adding a titanium oxide filler or a urea-formalin resin filler (Non-Patent Document 1) has been proposed.

As a technique for improving the degree of oil absorption and preventing strike-through, for example, a hydrated silicic acid slurry is added to a paper material containing pulp and calcium carbonate to make a paper, and the oil absorption amount and pore volume of the hydrated silicic acid are obtained. , Filler inner paper (Patent Document 3) in which the average particle size and the like are set within a specific range, and newspaper paper (Patent Document 3) in which the ratio of these in ash content is mainly set within a specific range, mainly of white carbon and calcium carbonate. 4) etc. have been proposed.

Japanese Patent No. 5265900 Japanese Patent No. 3041297 Japanese Unexamined Patent Publication No. 09-176985 Japanese Unexamined Patent Publication No. 2002-201590

Paper Pa Gikyo Magazine 44, (8) 865 (1990)

However, these conventional techniques have the following problems.
(1) According to the technique described in Patent Document 1, although the opacity is improved by providing the pigment coating layer, the pigment coating layer inhibits the absorption of ink into the base paper during offset printing, and the ink drying property is improved. There is a possibility that the printing workability may be deteriorated, such as deterioration of the printing workability. In addition, pigment coating equipment is required, which is disadvantageous in terms of power and cost.
(2) According to the technique described in Patent Document 2, although the opacity is improved by the bulky effect, the bulky agent improves the paper thickness by inhibiting the hydrogen bond between the pulp fibers of the base paper, so that the surface strength is improved. Deterioration of printing workability such as piring and generation of paper dust becomes a problem.
(3) According to the techniques described in Patent Documents 3 and 4, and Non-Patent Document 1, white carbon, titanium oxide, and urea-formalin resin fillers are expensive in the first place, which leads to an increase in cost. In particular, white carbon tends to cause paper dust generation and stains on printing equipment due to its particle characteristics, so there is a limit to increasing the amount of white carbon added in consideration of maintaining the paper quality strength.
(4) In newspaper paper, although there are many technologies related to workability during printing, there is no technology that takes into consideration human senses such as suppleness when turning pages.

In view of such a situation, the present invention provides a newspaper paper containing used paper pulp, having a low basis weight and a high ash content, having moderate stiffness of the paper, being hard to strike through, and being easy to turn. Is the subject.

As a result of diligent studies to solve the above problems, the present inventors have found that the ^{ash content in paper contains recycled paper pulp, has a basis weight of 45 g / m 2} or less, and is measured by the 525 ° C. combustion method described in JIS-P8251. Is 10% by mass or more of newspaper paper without a pigment coating layer, contains light calcium carbonate added at the time of papermaking, and has ash content in paper and JIS measured by the 525 ° C. combustion method described in JIS-P8251. -A newspaper paper having a difference of 2.0% by mass or more from the ash content in the paper measured by the 900 ° C. combustion method described in P8252 and a specific scattering coefficient of 50 m ² / kg or more contains used paper pulp. We have found that we can obtain newspaper paper that has a low basis weight and high ash content, has moderate stiffness, is hard to strike through, and is easy to turn over, and has completed the present invention. As the calcium carbonate, it is preferable to use fresh light calcium carbonate. Further, the mechanical pulp is preferably contained in an amount of 5% by mass or more and 30% by mass or less based on the absolute dry mass of the total pulp, and the mechanical pulp is more preferably a thermomechanical pulp (TMP) or a refiner ground pulp (RGP). Further, the bending stiffness of newspaper paper is preferably 70 μN · m or less. Further, the tissue softness measuring device TSA is used to push the rotor with a blade from above as a pushing pressure of 100 mN with respect to the newspaper sample installed on the sample table, and then rotate the sample at a rotation speed of 2.0 (/ sec). When the vibration of the sample table was measured by the vibration sensor, the intensity (TS750) of the maximum peak of the first spectrum from the low frequency side automatically acquired by the software on the TSA was 70 dBV ² rms or less, and 6500 Hz. It is preferable that the intensity (TS7) of the maximum peak of the spectrum containing the above is 130 dBV ^{2 rms or less.}

The newspaper paper of the present invention contains recycled paper pulp, has a low basis weight and a high ash content, and has the advantages of having moderate paper stiffness, being hard to strike through, and being easy to turn. In particular, it is supple, soft, and easy to turn. Newspapers are usually delivered or sold in four or two folds with a number of relatively large, thin sheets of 813 x 545 mm stacked on top of each other. When reading a newspaper, fold it in half or unfold it in an unfolded state, and read it while turning it one by one. Since the newspaper paper of the present invention bends flexibly, it is easy to turn over. Also, especially when reading a newspaper in a crowded place by rolling it vertically and holding it with one hand and turning it with the other hand, or when reading by rolling the finished part to the back little by little. Are suitable.

It is a figure which shows the measurement principle of the tissue softness measuring apparatus TSA. It is a figure which shows an example of the analysis result of the vibration frequency of a paper sample by TSA. It is a figure which shows the measuring method of the rigidity D of a paper sample sample by TSA.

As described above, in the present invention, the waste paper pulp is contained, the basis weight is 45 g / m ² or less, and the ash content in the paper measured by the 525 ° C. combustion method described in JIS-P8251 is 10% by mass or more. It is a newspaper paper without a work layer, contains light calcium carbonate added at the time of paper making, and has ash content in paper measured by the 525 ° C. combustion method described in JIS-P8251 and the 900 ° C. combustion method described in JIS-P8252. By using newspaper paper with a difference of 2.0% by mass or more from the ash content in the paper measured in 1 and a specific scattering coefficient of 50 m ² / kg or more, it contains recycled paper pulp, has a low basis weight, and has a high ash content. However, it is possible to obtain newspaper paper that has moderate stiffness, is hard to strike through, and is easy to turn.

<Newspaper>
1) Pulp The raw material pulp in the newspaper of the present invention contains waste paper pulp in consideration of the environment, and in addition to waste paper pulp, wood such as coniferous tree (N material) or broadleaf tree (L material), bamboo, etc. Chemical pulp (KP, SP, etc.) obtained from non-wood fibers such as straw and hemp, mechanical pulp (GP, CGP, RGP, PGW, TMP, CTMP, etc.), dissolving pulp, etc. are mixed and used in any ratio. be able to. As the used paper pulp, deinked used paper pulp (DIP) and non-deinked used paper pulp can be used, but it is desirable to add a high amount of DIP from the viewpoint of whiteness, and the DIP is 50 mass per absolute dry mass of the total pulp. % Or more, preferably 70% by mass or more, and more preferably 80% by mass or more. Further, the mechanical pulp and DIP can be bleached and used as needed, and the degree of bleaching can be arbitrarily performed. Further, in order to produce newspaper paper having sufficient strength, it is preferable to contain mechanical pulp, and thermomechanical pulp (TMP) or refiner ground pulp (RGP), which causes less damage to fibers during pulp production, is more preferable. The mechanical pulp can be mixed and used in an arbitrary ratio, but in order to achieve both strength and suppleness of the paper, 5% by mass or more and 30% by mass or less are preferable.

2) Filler As a type of filler (internal filler) added in the present invention, light calcium carbonate is used because it has a high specific scattering coefficient, high oil absorption and is effective in improving print quality such as strike-through. Suitable, especially "fresh" light calcium carbonate, which has never been incorporated into paper, is preferred. Since fresh light calcium carbonate has a controlled shape as compared with a reclaimed filler, it is considered to have excellent oil absorption and light scattering properties and contribute to the development of suppleness. The filler may be light calcium carbonate alone, or light calcium carbonate may be used in combination with one or more other fillers. Examples of fillers other than light calcium carbonate include known papermaking fillers such as heavy calcium carbonate, hydrated silicic acid, white carbon, talc, kaolin, clay, titanium oxide, and synthetic resin fillers, but are limited thereto. It is not something that will be done.

In the present invention, "JIS-P8251 paper, paperboard and pulp-ash content test method-525 ° C."
The ash content in the paper measured by the method described in "Combustion Method" is preferably 10% by mass or more from the viewpoint of preventing strike-through. More preferably, it is 11.5% by mass or more. The upper limit of the amount of ash in the paper is not particularly limited, but it is usually about 40% by mass or less, preferably 30% by mass or less, considering the operability at the time of manufacturing and the processability at the time of printing.

In the present invention, since the opacity and whiteness of the paper can be improved at a relatively low cost, it is preferable to add light calcium carbonate as an internal filler. Further, in order to obtain supple newspaper paper, it is desirable that the addition rate of light calcium carbonate is high, and it is preferably 4% by mass or more, more preferably 5% by mass or more, based on the absolute dry mass of the total pulp. The upper limit is not particularly limited, but if the upper limit of the ash content in the paper and the ash content brought in from the used paper pulp are taken into consideration, it will usually be about 35% by mass or less.

In the present invention, "JIS-P8251 paper, paperboard and pulp-ash content test method-525 ° C."
The difference between the ash content measured by the method described in "Combustion method" and the ash content measured by the method described in "JIS-P8252 Paper, paperboard and pulp-ash content test method-900 ° C combustion method" is 2.0 mass. % Or more is preferable. Newspaper has various inorganic components (fillers and pigments) such as a certain amount of ash brought in from used paper, so it is easy and direct to measure the content of specific inorganic components in paper. It is difficult. However, with regard to calcium carbonate, it is generally known that when it is burned at a high temperature of about 900 ° C, it decomposes into carbon dioxide and water by combustion, which is known as a 525 ° C combustion method and 900 ° C combustion. It is possible to estimate the calcium carbonate content in the paper by using the ash content difference in the method. That is, it is shown that the larger the ash content difference is, the higher the calcium carbonate content is. In the present invention, the difference in ash content when the newspaper is burned at 525 ° C and 900 ° C is set to 2.0% by mass or more, and the calcium carbonate content in the paper is increased to effectively strike through or turn pages. Ease can be improved. The upper limit of the ash content difference is not particularly limited, but if the upper limit of the ash content in the paper is taken into consideration, it will usually be about 35% by mass or less.

3) Papermaking system The newspaper paper of the present invention may be either acid-free paper or acid-free paper that is neutrally paper-made so that the surface pH is 6 to 9, and is not particularly limited. However, in the case of neutral papermaking, it is possible to add a high amount of calcium carbonate as a filler, so acid-free paper is preferable in terms of quality such as strike-through and suppleness.

4) Internal chemicals, etc. Although the types and amounts of internal chemicals used in acidic papermaking and neutral papermaking differ, they are conventionally known internal chemicals, alkyl ketene dimer (AKD) -based sizing agents, and alkenyl anhydrous. A succinic acid (ASA) -based sizing agent, a neutral rosin sizing agent, or the like can be used.

In addition, various conventionally used nonionic and cationic yield improving agents, drainage improving agents, paper strength improving agents, bulking agents, and other internal chemicals for papermaking are appropriately selected as necessary. Can be used. Further, for example, a basic aluminum compound such as a sulfate band, aluminum chloride, basic aluminum chloride, or basic polyaluminum hydroxide may be added internally. Other various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide, polyamine resin, polyamine, polyethyleneimine, polyamide epichlorohydrin, polyamine epichlorohydrin, vegetable gum, etc. Various compounds such as polyvinyl alcohol, latex, polyethylene oxide, hydrophilic crosslinked polymer particle dispersion and derivatives or variants thereof can be used. Further, it is also possible to appropriately add an internal chemical for papermaking such as a dye, a fluorescent whitening agent, a pH adjuster, a defoaming agent, a pitch control agent, and a slime control agent, depending on the intended use.

5) Surface treatment agent In order to improve the surface strength and printability, a surface treatment agent containing a surface paper strength agent, a surface sizing agent, etc. can be applied on the base paper of newspaper paper to provide a clear coating layer. ..

Examples of the surface paper force agent include starch-based starch typified by starch, enzyme-modified starch, thermochemically modified starch, oxidized starch, esterified starch, etherified starch, hydroxyethylated starch, and cationized starch, and polyvinyl alcohol (PVA). , Carboxyl-modified polyvinyl alcohol, polyvinyl alcohol-based such as cationic-modified polyvinyl alcohol, polyacrylamide-based such as polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, nonionic polyacrylamide, cellulose-based such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, etc. Examples thereof include various copolymers (latex) such as water-soluble polymer, styrene / butadiene type, styrene / acrylic type, ethylene / vinyl acetate type, butadiene / methyl methacrylate type, vinyl acetate / butyl acrylate type. These may be used alone or in admixture of two or more.

As the surface sizing agent, a cationic surface sizing agent is preferable in the case of neutral fabrication, for example, a styrene / (meth) acrylic acid copolymer (note that "(meth) acrylic acid" is "acrylic acid and / or methacrylic acid". ), Styline / (meth) acrylic acid ester copolymer, styrene / (meth) acrylic acid / (meth) acrylic acid ester copolymer, styrene / maleic acid copolymer, styrene / maleic acid half Ester copolymer, styrene / maleic acid ester copolymer, ethylene / (meth) acrylic acid copolymer, isobutylene / (meth) acrylic acid copolymer, n-butylene / (meth) acrylic acid / (meth) acrylic Examples thereof include, but are not limited to, acid ester copolymers, propylene / maleic acid copolymers, ethylene / maleic acid copolymers, and α-olefin-maleic acid-based copolymers. These copolymers may be used as sodium salts, potassium salts, or ammonium salts. Further, a nonionic surface sizing agent, an alkyl ketene dimer-based sizing agent, or the like can also be used in combination as long as the desired quality is not impaired.

In addition, Nepari inhibitor, wet paper strength agent, polyethylene glycol, preservative, antifoaming agent, UV inhibitor, optical brightener, dye, anti-fading agent, viscosity stabilizer, anti-slip agent, lubricant, polyethylene wax, ink Auxiliary agents such as fixing agents and metal salts can be used as appropriate.

6) Papermaking method The model of the papermaking machine is not particularly limited, and papermaking can be performed with a public papermaking machine such as a long net paper machine, a gap former, and a hybrid former (on-top former). Press line pressure is used within normal operating range. The surface treatment agent may or may not be applied. When the clear coating layer with the surface treatment agent is provided, the components of the surface treatment agent are not particularly limited, and the type of the size press is also not limited. A film transfer method size press or the like can be appropriately used.

7) Paper quality and other aspects The newspaper paper of ^{the present invention is manufactured so that the basis weight is 30 g / m 2} or more and 50 g / m ² or less, but the effects such as improvement of strike-through and suppleness of the present invention are obtained. Since it is expressed at a higher level, it is preferably a newspaper paper having a low basis weight of ^{45 g / m 2 or less.} More preferably, it is 43 g / m ² or less. When the surface treatment agent is applied (clear coating layer), the coating amount is not particularly limited, but is 0.1 g / m ² or more and 5.0 g / m ² or less per side. It is desirable to have. As a method for drying the clear coating layer, various methods such as a steam heating cylinder, a heated hot air air dryer, a gas heater dryer, and an electric heater dryer are used alone or in combination. Further, smoothing processing may be performed using a machine calendar, a super calendar, a high-temperature soft nip calendar, or the like, or uncalendar processing may be performed. If the smoothness is too high, sufficient paper thickness cannot be obtained and the paper becomes weak, while if the smoothness is too low, poor ink adhesion occurs when printing. Therefore, in the present invention, JIS-P8119: It is desirable to perform calendar processing so that the Beck smoothness measured according to 1998 is 30 to 70 seconds, preferably 35 to 60 seconds. The water content of newspaper paper is about 1.0% or more and 9.0% or less from the viewpoint of printing workability and ink inking property.

The newspaper of the present invention does not have a pigment coating layer. The pigment coating layer refers to a layer containing a pigment and a binder that is coated on the surface of the base paper after the paper is made.

The specific scattering coefficient of the newspaper of the present invention is 50 m ² / kg or more. The specific scattering coefficient can be calculated based on the formula specified in TAPPI T425 (ISO 9426). If the specific scattering coefficient is high, the paper will be less likely to show through even if the opacity is the same. ^{The upper limit of the specific scattering coefficient is not limited, but is usually about 80 m 2} / kg in consideration of 40% by mass, which is a guideline for the upper limit of the ash content in the paper. From the viewpoint of the balance between the ash content and the strength such as bending stiffness, 70 m ² / kg or less is more preferable. The specific scattering coefficient can be adjusted mainly by the type and amount of the filler used.

The bending stiffness of the newspaper of the present invention is preferably 70 μN · m or less. Bending stiffness can be measured as bending stiffness in the MD direction (papermaking direction) according to ISO2493. The moderately low bending stiffness improves the suppleness and softness of the paper, making it easy to turn. The lower limit of bending stiffness is not limited, but is usually about 30 μN · m in consideration of processing suitability and workability in a printing machine (particularly a folding machine). In order to achieve both ease of turning and processability at a high level, it is desirable that the content is 45 μN ・ m or more and 65 μN ・ m or less.

Further, in the present invention, it has been found that the ease of turning a newspaper correlates with a value measured by a Tissue softness measuring device TSA (Tissue Softness Analyzer), and this measured value can be used as an index. TSA is used for quantitative evaluation of hand feel in the fields of tissue paper products and sanitary thin paper rolls, and is described in, for example, JP2013-236903A and JP2014-233363A. It is a thing.

In the present invention, the printed newspaper is used as a sample, and the rotor with a blade is pushed in from above as a pushing pressure of 100 mN with respect to one sample installed on the sample table, and then rotated at a rotation speed of 2.0 (/ sec). When the vibration of the sample table is measured by the vibration sensor, the intensity (TS750) of the maximum peak of the first spectrum from the low frequency side automatically acquired by the software on TSA is 70 dBV ² rms or less. Is preferable, and more preferably 67 dBV ² rms or less, still more preferably 65 dBV ² rms. The lower limit is 50 dBV ² rms or more. The TS750 represents smoothness and roughness. If the TS750 is too high, the smoothness is inferior, and if the TS750 is too low, only the smoothness stands out, and a good tactile sensation may not be obtained.

Was also obtained automatically by software on the TSA, preferably has a maximum peak intensity of the spectrum (TS7) is 130dBV ² rms or less containing 6500Hz, more preferably 125dBV ² rms or less, and most preferably 120DBV ² It is less than or equal to rms. The lower limit is 90 dBV ² rms or more. TS7 shows a fluffy feeling (surface softness and bulk softness), and if TS7 is too high, sufficient softness cannot be obtained, and if it is too low, only softness stands out and a good tactile sensation may not be obtained. ..

Further, in the present invention, the measured value of the rigidity (D) by TSA is preferably 0.75 to 0.85 mm / N, more preferably 0.78 to 0.80 mm / N. If this measured value is too low, the suppleness of the entire newspaper will be inferior, and if it is too high, the suppleness will be noticeable, and the overall balance may be lost. Rigidity (D) means that when the sample installed on the sample table is pushed from above with the pushing pressures of 100mN and 600mN without rotating the rotor with blade, the sample is moved up and down between the pushing pressures of 100mN and 600mN, respectively. It is expressed by the amount of deformation and displacement in the direction.

As shown in FIG. 1 for details of the measuring method, the tissue softness measuring device TSA110 has vibration data detected by various sensors when the rotor 104 with a rotated blade is pressed from above the paper sample (sample) 106. Is measured by vibration analysis and parameterized (TS value) to quantitatively evaluate the softness (feel) of paper. Emtec Electronic GmbH of Germany (Japan agency is Nihon Rufuto Co., Ltd.) It is a product name made by.

Specific measurement using TSA is
(I) A sample 106 (a sample processed into a circle with a diameter of about 112.8 mm using an emtec sample punch) is placed so as to cover the circular sample table 105 from the outside, and the outer circumference of the sample 106 is covered with a sample fixing ring. Hold at 108,
(Ii) After pushing the rotor 104 with a blade from above the sample 106 with a pushing pressure of 100 mN, the rotor 104 is rotated at a rotation speed of 2.0 (/ sec).
(Iii) The vibration of the sample table 105 is measured by the vibration sensor 103 installed inside the sample table 105, and the vibration frequency is analyzed.

(Iv) Next, the amount of deformation displacement (mm / N, rigidity D) in the vertical direction when the sample 106 is deformed without rotating the rotor 104 at pushing pressures of 100 mN and 600 mN is measured.

According to the above procedure, one sample is measured 5 times and averaged.

The sample table 105 is installed on the base plate 101, and the force sensor 102 is arranged between the sample table 105 and the base plate 101. Then, the pushing pressure of the rotor 104 with a blade is controlled by the detection value of the force sensor 102. Further, the rotor 104 with blades is rotated by the motor 109.

The emtec measurement system is used as software for vibration analysis and parameterization (TS value). This software is equipped with various algorithms (for example, Base Tissue, Facial, TP, etc.) and automatically acquires TS750, TS7, D (rigidity) on the software, and these TS750, TS7, D, and basis weight. The HF (hand feel) value is calculated according to the type of various algorithms from the thickness, the number of Ply, and the like. In the present invention, only TS750, TS7, and D are specified, not HF values. Any algorithm may be used as long as the above measurement conditions are satisfied, and the values of TS750, TS7, and D depend on the type of algorithm. It doesn't change.

FIG. 2 shows an example of the analysis result of the vibration frequency of the paper sample by TSA. Let TS750 be the intensity of the maximum peak A of the first spectrum from the low frequency side, and TS7 be the intensity of the maximum peak B of the spectrum including 6500 Hz (around 6500 Hz). The maximum peak B is usually located at about 6500 Hz.

FIG. 3 shows a method of measuring the rigidity D of a paper sample by TSA.

The vibration frequency of the paper sample sample depends on the structure of the paper and the rotation speed of the rotor 104, and the amplitude (intensity of the spectrum) depends on the height of the structure of the paper such as the height of the crepe. The frequency at which TS7 appears (range of 5000 to 8000 Hz, usually around 6500 Hz) is the resonance frequency of the rotor 104, and when it becomes horizontal vibration and travels on the paper surface, it is momentarily cut off by the paper fiber and the rotor 104 vibrates. to cause.

The opacity of the newspaper of the present invention is preferable because it is difficult to strike through when it is high, and it is preferably 93% or more. Opacity can be measured according to JIS-P8149: 2000. The upper limit of the opacity is not limited, but is about 96% in consideration of the low basis weight of newspaper paper. Further, in the present invention, the strike-through value is preferably 85% or more. Here, the strike-through value is set so that the print surface density measured by the Macbeth reflectance densitometer is 1.15, and the printed surface is left for 24 hours under a humidity control condition of 23 ° C. and 50 RH%. It is a value obtained by measuring the reflectance of the back surface and dividing the reflectance of the printed back surface by the reflectance of the unprinted back surface. The larger this value, the less strike-through.

In the present invention, if the coefficient of friction is too high, pages stick to each other when reading a newspaper, and if the coefficient of friction is too low, slipping is difficult to occur. Therefore, the coefficient of static friction measured by the ISO horizontal method according to JIS-P8147: 2010 is preferably 0.62 to 0.69, and the coefficient of dynamic friction is also preferably 0.59 to 0.62. When the coefficient is in these ranges, it is possible to obtain a newspaper that is easy to turn and read.

The newspaper of the present invention is usually a newspaper roll-up paper wrapped in a paper tube, but the present invention is not limited to this. The method of winding up the manufactured newspaper to make it into a newspaper winding paper is not particularly limited, and the newspaper of the present invention can be wound up by a winder (winding machine). The take-up speed and tension (tensile strength) may be appropriately adjusted according to the required characteristics of the newspaper.

Further, the paper tube to be wound when the newspaper paper of the present invention is used as a paper roll is not particularly limited, but since it can be a supple paper roll that suppresses the occurrence of wrinkles, it is mainly made of used corrugated cardboard. A paper tube base paper in which the paper tube base paper and the liner are wound, the outermost layer is wound with the liner once or more, and the other layers are wound with the paper tube base paper 19 times or more may be used. Preferably, the total number of windings of the paper tube base paper and the liner is 24 or more. By wrapping a liner with high smoothness on the outside, it is possible to smooth the surface of the paper tube and prevent wrinkles and bumps on the newspaper that are formed along the shape of the surface of the paper tube. Further, the obtained paper tube is seasoned at room temperature (room temperature) for 5 days or more to adjust the water content of the paper tube to 6.5-9.0%. When adjusted by this method, the difference in water content between the inside and the outside of the paper tube is eliminated, and it is possible to suppress the occurrence of wrinkles during newspaper rolls and printing due to deformation and dimensional change of the paper tube, which is preferable.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, parts and% in the example indicate parts by mass and% by mass, respectively, and the numerical range is described as including the end points thereof.

(1) Measurement of basis weight The measurement was performed in accordance with the "basis weight measurement method" described in JIS-P8124.

(2) Measurement of paper thickness Measurement was performed in accordance with "Paper and Paperboard-Thickness and Density Test Method" described in JIS-P8118.

(3) Opacity Measured according to JIS-P8149: 2000.

(4) Specific scattering coefficient Calculated based on the formula specified in TAPPI T425 (ISO 9426).

(5) ISO bending stiffness The bending stiffness in the MD direction (papermaking direction) was measured according to ISO2493.

(6) JIS friction coefficient The static friction coefficient and the dynamic friction coefficient were measured according to the ISO horizontal method described in JIS-P8147: 2010.

(7) Measurement of TS750, TS7, and D values The measurement was performed using the above-mentioned tissue softness measuring device TSA. The measurement conditions are also as described above.

(8) Strike-through value Using an offset newspaper ink using an RI printing machine, single-sided printing was performed so that the stamp surface density measured by the Macbeth reflection densitometer was 1.15. The printed paper was left in an atmosphere of 23 ° C. and 50 RH%, and after humidity control for 24 hours, the reflectance of the back surface of the printed surface was measured with a Macbeth reflectance densitometer, and the strike-through value was calculated by the following formula:
Show-through value (%) = (reflectance on the back side of printing / reflectance on the back side of unprinted) × 100.

(9) Ash content (525 ° C)
The measurement was performed in accordance with "Paper, Paperboard and Pulp-Ash Test Method-525 ° C. Combustion Method" described in JIS-P8251.

(10) Ash content (900 ° C)
The measurement was performed in accordance with "Paper, Paperboard and Pulp-Ash Test Method-900 ° C. Combustion Method" described in JIS-P8252.

(11) strike-through (visual evaluation)
Printing was performed using an offset rotary press (Toshiba offset rotary press: OA-4B2T-600) using high-viscosity AF ink, which is an eco-ink for offset, manufactured by Toyo Ink Mfg. Co., Ltd. The printed paper was left in an atmosphere of 23 ° C. and 50 RH%, and the strike-through 24 hours after leaving was visually evaluated according to the following criteria.
⊚: Ink has not penetrated the back side of the print.
◯: Almost no ink has penetrated the back side of the print.
Δ: Some ink has penetrated into the back surface of the print.
X: Ink has penetrated the back surface of the print.

(12) Ease of turning After printing with the offset rotary printing press, the paper was cut into a size of 545 × 813 (mm) so that the papermaking direction was the short side, and 10 sheets were stacked and folded in half. The newspaper folded in half was folded in four, which is the size to be delivered. The ease of turning pages when turning one sheet at a time while holding the newspaper folded in half was evaluated according to the following criteria.
◎: Very supple and easy to turn.
○: Supple and easy to turn.
△: It is stiff and difficult to turn.
×: Very stiff and difficult to turn.

(13) Average particle size of filler Using a laser diffraction / scattering type particle size distribution measuring instrument (manufactured by Malvern Co., Ltd., device name: Mastersizer 2000), the 50% point of the cumulative volume distribution was defined as the average particle size.

(Example 1)
<Manufacturing of newspaper>
As a papermaking pulp, a filler is added to a pulp slurry in which newspaper deinked pulp (water freeness 150 ml CSF), TMP (water freeness 80 ml CSF), and NKP (water freshness 500 ml CSF) are mixed in a blending ratio of 80:15: 5% by mass. As a result, light calcium carbonate (average particle size 4.1 μm) was added in an amount of 4.0% by mass based on the absolute dry mass of pulp to prepare a paper material. Using this paper material, a base paper for newspaper paper is made with a gap former type twin wire paper machine at a paper making speed of 1000 m / min, and then a hydroxyethylated starch is applied with an on-machine gate roll coater to felt the amount of felt. Both the surface and the wire surface were ^{coated so as to be 0.2 g / m 2} , to obtain a newspaper for offset printing having a basis weight of about 42 g / m ² (42.3 ^{g / m 2).} The paper quality, ash content, strike-through, and ease of turning were measured, and the results are shown in Table 1.

(Example 2)
A newspaper for offset printing was obtained in the same manner as in Example 1 except that the addition rate of the filler was 5.0% and the basis weight was about 44 g / m ^2.

(Example 3)
A newspaper for offset printing was obtained in the same manner as in Example 1 except that the addition rate of the filler was 5.0% and the basis weight was about 43 g / m ^2.

(Examples 4 to 8)
The same procedure as in Example 1 was performed except that the filler addition rates were 5.0%, 6.0%, 7.0%, 10.0%, and 11.0%, respectively, and the offset printing newspaper was prepared. Obtained.

(Example 9)
The same procedure as in Example 1 was carried out except that the addition rate of the filler was 11.0% and the basis weight was 37.5 g / m ^{2, to obtain a newspaper for offset printing.}

(Example 10)
The same procedure as in Example 1 was carried out except that the blending ratio of the newspaper deinked pulp, TMP and NKP was 65:30: 5% by mass and the addition rate of the filler was 6.0% to obtain newspaper for offset printing. ..

(Example 11)
The same procedure as in Example 1 was carried out except that the blending ratio of the newspaper deinked pulp, TMP and NKP was 85:10: 5% by mass and the addition rate of the filler was 6.0% to obtain newspaper for offset printing. ..

(Example 12)
The same procedure as in Example 1 was carried out except that the blending ratio of the newspaper deinked pulp, TMP and NKP was 92: 3: 5% by mass and the addition rate of the filler was 6.0% to obtain newspaper for offset printing. ..

(Example 13)
The same procedure as in Example 1 was carried out except that the blending ratio of the newspaper deinked pulp, TMP and NKP was 95: 0: 5% by mass and the addition rate of the filler was 6.0% to obtain newspaper for offset printing. ..

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the blending ratio of newspaper deinked pulp, TMP, and NKP was 65:30: 5% by mass, the addition rate of the filler was 0%, and the basis weight was about 44 g / m ^2. I got a newspaper for printing.

(Comparative Example 2)
The same procedure as in Example 1 was performed except that the blending ratio of newspaper deinked pulp, TMP, and NKP was 70: 25: 5 mass%, the addition rate of the filler was 0%, and the basis weight was about 44 g / m ^2. I got a newspaper for printing.

(Comparative Example 3)
The same procedure as in Example 1 was performed except that the blending ratio of newspaper deinked pulp, TMP, and NKP was 75:20: 5% by mass, the addition rate of the filler was 0%, and the basis weight was about 44 g / m ^2. I got a newspaper for printing.

(Comparative Example 4)
The same procedure as in Example 1 was carried out except that the addition rate of the filler was 0% and the basis weight was about 45 g / m ^{2, to obtain a newspaper for offset printing.}

(Comparative Example 5)
The same procedure as in Example 1 was carried out except that the addition rate of the filler was 0% and the basis weight was about 43 g / m ^{2, to obtain a newspaper for offset printing.}

(Comparative Example 6)
The same procedure as in Example 1 was carried out except that the addition rate of the filler was 0% and the basis weight was about 41 g / m ^{2, to obtain a newspaper for offset printing.}

(Comparative Example 7)
The same procedure as in Example 1 was carried out except that the addition rate of the filler was 1.0%, to obtain a newspaper for offset printing.

(Comparative Example 8)
The same procedure as in Example 1 was carried out except that the addition rate of the filler was set to 3.0%, to obtain a newspaper for offset printing.

(Comparative Example 9)
Heavy calcium carbonate (average particle size 3.8 μm) was used as a filler, and the same procedure as in Example 1 was carried out except that the filler addition rate was 5.0% to obtain a newspaper for offset printing.

(Comparative Example 10)
Heavy calcium carbonate (average particle size 3.8 μm) was used as a filler, and the same procedure as in Example 1 was carried out except that the filler addition rate was 11.0% to obtain a newspaper for offset printing.

(Comparative Example 11)
Kaolin (average particle size 6.2 μm) was used as a filler, and the same procedure as in Example 1 was carried out except that the filler addition rate was 5.0% to obtain a newspaper for offset printing.

(Comparative Example 12)
Kaolin (average particle size 6.2 μm) was used as the filler, and the same procedure as in Example 1 was carried out except that the filler addition rate was 11.0% to obtain a newspaper for offset printing.

As shown in Table 1, the newspaper paper of the present invention has a high waste paper pulp content, ^{a low basis weight of 45 g / m 2} or less, and a high ash content (525 ° C. ash content) of 10% by mass or more. It can be seen that strike-through is unlikely to occur and it is easy to turn over. The newspaper paper of the present invention has both moderate stiffness and suppleness (softness), and is most suitable for newspaper applications such as reading thin relatively large-sized paper one by one.

101 Base plate 102 Force sensor 103 Vibration sensor 104 Rotor with blade 105 Sample stand 106 Sample 108 Fixed ring 109 Motor 110 Tissue softness measuring device TSA

Claims (7)

A newspaper paper containing used paper pulp, having a basis weight of 43 g / m ² or less, having an ash content of 10% by mass or more in paper measured by the 525 ° C. combustion method described in JIS-P8251, and having no pigment coating layer. There,
As a filler added at the time of papermaking, only fresh light calcium carbonate (excluding pre-aggregate filler) is included.
Bending stiffness is 58 μN ・ m or less,
Deinked recycled paper A newspaper having a pulp content of 80% by mass or more and an opacity of 94.4% or more per absolute dry mass of the total pulp. The first aspect of claim 1, wherein the difference between the ash content in paper measured by the 525 ° C. combustion method described in JIS-P8251 and the ash content in paper measured by the 900 ° C. combustion method described in JIS-P8252 is 2.0% by mass or more. Newspaper. Newsprint according to claim 1 or 2 blending ratio of mechanical pulp, characterized in that at least 5% by mass per the total pulp absolute dry mass. The newspaper paper according to claim 3, wherein the mechanical pulp is a thermomechanical pulp (TMP) or a refiner ground pulp (RGP). The coating amount of the clear coating layer is 0.2 g / m per side. ² The newspaper paper according to any one of claims 1 to 4, which is as follows. The tissue softness measuring device TSA pushes the rotor with a blade from above as a pushing pressure of 100 mN with respect to the newspaper sample installed on the sample table, and then rotates the sample at a rotation speed of 2.0 (/ sec). When the vibration of the table is measured by the vibration sensor, the intensity (TS750) of the maximum peak of the first spectrum from the low frequency side automatically acquired by the software on TSA is 70 dBV ² rms or less, and includes 6500 Hz. The newspaper according to any one of claims 1 to 5, wherein the maximum peak intensity (TS7) of the spectrum is 130 dBV ^{2 rms or less.} Printing is performed so that the printing surface density measured by the Macbeth reflectance densitometer is 1.15, and the humidity is adjusted for 24 hours in an environment of 23 ° C. and 50 RH%, and then the reflection on the back surface of the printed surface by the Macbeth reflectance densitometer. When measuring the rate, the following equation:
Show-through value (%) = (Reflectance on the back side of printing / Reflectance on the back side of unprinted) x 100
In wherein the print-through value calculated is 85% or more, newsprint according to any one of claims 1-6.

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