JP2008095265A - Newsprint for offset printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a newsprint for offset printing having high opacity after printing, high printability, internal binding strength and surface strength. <P>SOLUTION: In the newsprint for offset printing, a metal compound content in porous filler composed of an aggregate obtained by aggregating silicone dioxide and a metal compound is 0.10-8.0 mass% expressed in terms of oxide based on 100 mass% silicon dioxide. The newsprint contains 0.5-10.0 mass% porous filler having 10-150 m<SP>2</SP>/g specific surface area, 0.10-0.80 μm pore diameter and 16-40 μm average particle diameter as filler in paper. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

An object of the present invention is to provide a newsprint for offset printing having low post-printing opacity, high post-print opacity, printability and internal bond strength, and surface strength.

  Offset printing is the mainstream of recent commercial printing methods, including newspaper printing. Offset printing is a method in which a printing plate, usually called a PS plate, is prepared and dampening water and ink are supplied to the printing plate for printing. The printing plate is a lithographic plate, and the image area on the printing plate is treated to have an oleophilic surface, and the non-image area is treated to have a hydrophilic surface. When dampening water and ink are supplied to the printing plate, ink is attached to the image area and water is attached to the non-image area, and the ink is transferred from the printing plate to the paper through the blanket for printing. To do.

  In this offset printing, since ink with relatively strong tack is used, the paper is required to have high internal bond strength and surface strength. In addition, when dampening water adheres to the paper surface, if paper with low internal bond strength or surface strength is used, paper dust accumulates on the blanket or mixes with ink, so-called blurring occurs on the printing surface. In addition to troubles, paper out troubles may occur.

  In addition, in recent years, there has been a demand for weight reduction in newsprint paper, and accordingly, there is an increasing demand for paper that can maintain high opacity after printing. In order to increase the opacity of paper, white carbon, Inorganic pigments such as calcium carbonate, titanium oxide, and talc have been widely used as fillers for papermaking. These inorganic pigments inhibit the bonding force between fibers and cause a decrease in internal bonding force and surface strength. In addition, DIP (deinked waste paper pulp), which is regarded as important in terms of the environment, has a high rate of blending. DIP has less opacity than mechanical pulps such as GP, RGP, and TMP. It is extremely difficult to achieve both high rate blending.

  Various proposals have been made to improve the above-mentioned problems. For example, by using a starch composition for paper coating in which a high-viscosity starch and a low-viscosity starch are blended as a surface treatment agent, surface strength and paper strength are improved. And a method for improving the affinity with a filler (see Patent Document 1) has been proposed. However, the proposed method does not have the effect of increasing ink fillability and opacity after printing, and the effect of suppressing blanket piling is not sufficient. Furthermore, there is almost no effect of preventing water breakage and there is a problem in printing workability.

  A method for suppressing surface strength and elution rate with respect to a dampening aqueous solution by using a surface sizing agent composition for printing paper comprising amylopectin content of 95% by weight or more and a water-resistant agent. (See Patent Document 2). However, in this composition, since the penetration of the fountain solution into the base material cannot be sufficiently suppressed, there is almost no effect of preventing water breakage. In addition, although the elution of amylopectin can be suppressed, the slight swelling of the amylopectin component, which is the main factor of the Nepali phenomenon, cannot be suppressed, so that the effect of improving the Nepali phenomenon is insufficient. Furthermore, in any of the above methods, the surface of the newsprint is low in hydrophobicity, so that the adhesion of the ink component is inferior, and it is difficult to obtain a high ink density on the paper. In addition, since the coating agent is highly hydrophilic and has no ink absorbability, there is no improvement in opacity after printing.

  Furthermore, as a means for improving ink fillability and opacity after printing, a method of applying various pigments has been proposed. Satin white, hydrated silicic acid, and hollow organic pigments can be applied to improve whiteness, opacity, and post-print opacity with a small amount of coating, but the bonding strength with the adhesive is weak and blanket piling is not possible. Since it deteriorates, it is necessary to increase the adhesive ratio, and as a result, the effect on opacity is reduced, which is not preferable in terms of cost (see Patent Documents 3, 4, and 5).

As described above, the opacity after printing is remarkably improved, the surface strength can be further increased, piling can be prevented, and the high internal bond strength is limited by the conventional method, and the target high level of quality. It was difficult to get.
Japanese Patent Laid-Open No. 5-195490 Japanese Unexamined Patent Publication No. 9-78495 JP 2000-34694 A JP 2001-164494 A JP 2000-314097 JP

An object of the present invention is to provide a newsprint for offset printing having a low basis weight, high post-print opacity, printability and internal bond strength, and surface strength.

The present invention employs the following configurations (1) to (4) in order to solve the above-described problems related to newsprint for offset printing.
(1) silicon-containing particles formed from silicon dioxide and / or silicate, and 0.1 to 8.0% by mass of a metal compound in terms of oxide with respect to 100% by mass of the silicon-containing particles, A porous filler having a specific surface area of 10 to 150 m ² / g, a pore size of 0.10 to 0.80 μm, and an average particle size of 16 to 40 μm is 0.5 to 10% with respect to 100% by mass of pulp. Newsprint paper for offset printing containing 0.0% by mass.
(2) The newsprint for offset printing according to (1), wherein the internal bond strength (J.TAPPI No. 18-2) is 150 J / m ² or more.
(3) Newsprint paper for offset printing according to (1) or (2), wherein the basis weight is 45 g / m ² or less and the opacity after printing is 91% or more.
(4) Newsprint paper for offset printing according to any one of (1) to (3), wherein 50% by mass or more of deinked waste paper pulp is contained in 100% by mass of the pulp.

The newsprint for offset printing according to the present invention has a low basis weight, high post-printing opacity, high internal bond strength, high surface strength, and excellent printability.

The present invention contains silicon-containing particles formed from silicon dioxide and / or silicate, and 0.1 to 8.0% by mass of a metal compound in terms of oxide with respect to 100% by mass of the silicon-containing particles. A porous filler having a specific surface area of 10 to 150 m ² / g, a pore diameter of 0.10 to 0.80 μm, and an average particle diameter of 16 to 40 μm is defined as 0. By containing 5 to 10.0% by mass, the drying shrinkage of the porous filler that contributes to opacity after printing in the paper-making process can be prevented, the ink absorption during printing can be kept high, and the opacity after printing. Can be improved.

The porous filler contained in the base paper is composed of silicon dioxide and a metal compound.
The silicon dioxide constituting the porous filler is formed from, for example, silicon dioxide and / or silicate. Here, the silicate is a compound represented by the general formulas xM ₂ O · ySiO ₂ , xMO · ySiO ₂ , xM ₂ O ₃ · ySiO ₂ , where M is Al, Fe, Ca, Mg, Na , K, Ti, Zn (x and y are arbitrary positive numerical values). Usually, silicon dioxide is in the form of particles.

  Examples of the metal element forming the metal compound contained in the porous filler include barium, titanium, aluminum, magnesium, calcium, nickel, iron, zirconium, and strontium. Specific examples of the metal compound include aluminum oxide, barium sulfate, magnesium carbonate, magnesium oxide, and magnesium hydroxide. Among these, aluminum oxide is preferable because of its excellent cost and handleability. The shape of the metal compound may be particulate or indefinite.

Content of the metal compound in a porous filler is 0.1-8.0 mass% in conversion of an oxide with respect to 100 mass% of silicon dioxide, Preferably it is 0.1-4.3 mass%. If the content of the metal compound is 0.1% by mass or more in terms of oxide with respect to 100% by mass of silicon dioxide, the viscosity in the slurry state can be lowered, the handling is good, and the content of the metal compound is If it is 8.0% by mass or less in terms of oxide with respect to 100% by mass of silicon dioxide, it is possible to increase the opacity after printing without destroying the porous filler by shear when blended in paper. I found it.
The metal compound content is determined by tableting a porous filler powder sample, measuring the content of each element with a fluorescent X-ray analyzer using the tableted sample as a measurement sample, It is calculated | required by converting into an oxide amount.

The specific surface area of the porous filler is 10 to 150 m ² / g and the pore diameter is 0.10 to 0.80 μm, preferably the specific surface area is 20 to 100 m ² / g and the pore diameter Is 0.15 to 0.50 μm. When the specific surface area is 10 to 150 m ² / g and the pore diameter is 0.10 to 0.80 μm, the binding strength of the aggregate structure constituting the porous filler can be increased, Even if pressure is applied during the pressure finishing treatment, the aggregated structure is not easily destroyed, so that sufficient oil absorption can be maintained when blended with the base paper, and high post-print opacity can be obtained.
Further, since the specific surface area and the pore diameter of the porous filler are in the above ranges, excessive aggregation and destruction of the aggregated structure are prevented, so that the opacity after printing can be increased. In addition, a narrow particle size distribution can be maintained, and the internal bond strength and surface strength of the paper can be increased.
The specific surface area in the present invention is a value measured by a mercury intrusion method, and is the surface area of all pores assuming that the pore shape is a geometric cylinder. The pressure in the measurement range and the amount of mercury injected The value obtained from the relationship.
The pore diameter in the present invention is a value measured by a mercury intrusion method and is a median pore diameter obtained from an integral specific surface area curve.

The average particle diameter of the porous filler is 16 to 40 μm. If the average particle size of the porous filler is 16 μm or more, the fraction in the paper when blended into the paper is good, and the porous filler due to the share by repeatedly circulating in the papermaking system due to poor fractionation If the average particle diameter is 40 μm or less, it is possible to prevent the surface strength from being reduced due to dropping off of coarse particles present on the paper surface.
The average particle diameter in the present invention is a value that is 50% in volume integration as measured by a laser diffraction method.
The particle size distribution of the porous filler is preferably narrow, and specifically, the standard deviation (σ) of the particle diameter is preferably 0.490 or less, more preferably 0.400 or less. In such a particle size distribution, since both coarse particles and fine particles are smaller, the surface strength and the internal bond strength can be further increased when blended in paper.

  The content of the porous filler in the base paper is 0.5 to 10% by mass, and preferably 1 to 5% by mass. If the content of the porous filler is less than 0.5% by mass, the above-mentioned effects cannot be exhibited, and if it exceeds 10% by mass, the internal bond strength of the paper is lowered, which is not preferable.

(Method for producing porous filler)
The manufacturing method of the porous filler of this invention is demonstrated.
The method for producing a porous filler according to the present invention includes adding a mineral acid solution and a metal salt solution of a mineral acid to a stirred alkali silicate aqueous solution, and neutralizing the alkali silicate aqueous solution, whereby silicon oxide and metal In this method, a porous filler slurry is obtained by precipitating a porous filler composed of an agglomerate in which a compound is aggregated in water.

Although it does not restrict | limit especially as alkali silicate aqueous solution used with this manufacturing method, Sodium silicate aqueous solution or potassium silicate aqueous solution is preferable. The concentration of the alkali silicate aqueous solution is preferably 3 to 15% by mass because the porous filler can be efficiently produced. When the alkali silicate aqueous solution is a sodium silicate aqueous solution, SiO ₂ / Na ₂ O It is preferable that the molar ratio is 2.0 to 3.4.

The amount of the mineral acid metal salt solution added is such that 0.07 to 7.0% by mass of the metal element is added to the alkali silicate aqueous solution with respect to 100% by mass of the silicon oxide to be produced. When the present inventors investigated, if the addition amount of the metal salt solution of a mineral acid is made into the quantity by which 0.07 mass% or more of metal elements are added to alkali silicate aqueous solution with respect to 100 mass% of silicon oxides. It was found that the content of the metal compound in the porous filler can be 0.08% by mass or more in terms of oxide with respect to 100% by mass of silicon oxide. It was found that the particle size distribution can be narrowed and the internal bond strength when blended into paper can be increased. Moreover, when it was set as the slurry, it turned out that the viscosity can be made small and handling can be improved. Further, if the metal element of 7.0% by mass or less is added to the alkali silicate aqueous solution with respect to 100% by mass of silicon oxide, the content of the metal compound in the porous filler is 100% by mass of silicon oxide. It became clear that it can be 8.0 mass% or less with respect to oxide. And it became clear that the bulkiness effect was fully exhibited when it mix | blended with paper, and the porous filler with high opacity of a white paper was obtained.
Moreover, since the content of the metal compound in the porous filler can surely be 0.08 to 8.0% by mass in terms of oxide with respect to 100% by mass of silicon oxide, the addition amount of the metal salt solution of the mineral acid can be reduced. The amount added to the alkali silicate aqueous solution is preferably 0.08 to 4.3% by mass in terms of oxide with respect to 100% by mass of silicon oxide.

  In the mineral acid solution and the mineral acid metal salt solution, examples of the mineral acid include hydrochloric acid, sulfuric acid, and nitric acid, and the mineral acid metal salt includes sodium salt, potassium salt, and calcium salt of the mineral acid. And aluminum salts. Among these, sulfuric acid and aluminum sulfate are preferable from the viewpoint of cost and handling, and an aqueous solution is preferable.

  The addition amount of the mineral acid solution and the metal salt solution of the mineral acid is in the range of 90 to 150% of the theoretically required neutralization amount, and is an amount that adjusts the pH of the resulting slurry to more than 2.5 and to 10 or less. Preferably there is. When the addition amount of the mineral acid solution and / or the metal salt solution of the mineral acid is less than 90% of the theoretically required neutralization amount or the pH of the resulting slurry exceeds 10, the alkaline silicate aqueous solution as the raw material There is a lot of waste. On the other hand, if it exceeds 150% of the theoretically necessary neutralization amount or the pH of the resulting slurry is 2.5 or less, the filtrate pH generated when concentrating the porous filler becomes too low and difficult to handle. Become.

At the time of precipitation of the silicon-containing particles, it is preferable to stir at a speed of 5 to 15 m / sec with a stirring device. Here, the peripheral speed is an index of the shearing force, and the shearing force increases as the peripheral speed increases. When the peripheral speed is less than 5 m / sec, the shearing force is too small, and it may be difficult to obtain an appropriate average particle size and narrow particle size distribution.
On the other hand, when the peripheral speed at the time of precipitation exceeds 15 m / sec, the shearing force becomes too large, the particle size of the porous filler becomes small, and the internal bond strength may be lowered when blended in paper. In addition, the load power increases and the equipment costs increase.
As the stirring device, an agitator, a homomixer, a pipeline mixer or the like is preferable. Although it is possible to use a pulverizer such as a ball mill or a sand grinder, it is not preferable because problems such as an increase in fine particles and a thickening of the slurry tend to occur.

The mineral acid solution and the metal salt solution of the mineral acid may be added to the alkali silicate aqueous solution all at once, but since it has a better particle size distribution, it is added in two or more stages. It is preferable.
When adding the mineral acid solution and / or the metal salt solution of the mineral acid in two or more stages, since the particle size distribution is particularly good, the temperature of the first stage alkali silicate aqueous solution is set to 20 to 70 ° C., It is preferable to set it to 70 degreeC or more after the 2nd step | paragraph. In the first stage, it is preferable that the addition amount of the mineral acid solution and / or the metal salt solution of the mineral acid is in the range of 10 to 50% of the theoretically required neutralization amount.

In both the first and second stages, the mineral acid solution and / or the metal salt solution of the mineral acid can be added all at once or continuously to the alkali silicate aqueous solution.
After completion of the addition of the mineral acid solution and / or the metal salt solution of the mineral acid, an aging step of stirring while maintaining the temperature at the time of addition may be included as necessary.

  When adding the mineral acid solution and / or the metal salt solution of the mineral acid in one stage, the temperature of the alkali silicate aqueous solution is preferably 60 ° C. to the boiling point of the solution, and 75 ° C. to the boiling point of the solution. More preferably. The mineral acid solution and / or the metal salt solution of the mineral acid can be added to the alkali silicate aqueous solution all at once or continuously.

In the present invention, chemical pulp (NBKP, LBKP, etc.), mechanical pulp (GP, CGP, RGP, PGW, TMP, etc.), deinked waste paper pulp (DIP, etc.), etc. are used alone or mixed in any ratio as raw material pulp However, when the deinked waste paper pulp is contained in an amount of 50% by mass or more in the total pulp, the effect of the porous filler used in the present application is large, which is preferable. It is preferable to contain 0.5 to 10.0% by mass of the porous filler with respect to 100% by mass of the pulp. Addition of a porous filler with a good particle size distribution reduces the decrease in internal strength and surface strength. In addition, the paper layer is not easily crushed when the surface treatment is performed with a calender, and is bulky. The paper surface roughness is small and has good smoothness. However, when the content in the paper is less than 0.5% by mass, the above-described effects cannot be exhibited.
Further, it is possible to add paper fillers such as white carbon, clay, amorphous silica, talc, titanium oxide, calcium carbonate, etc., so long as they do not affect paper strength such as internal bond strength and surface strength. . Further, if necessary, papermaking chemicals such as an internal sizing agent, a fixing agent, a paper strength enhancer, a yield improver, a water resistance agent, and an ultraviolet absorber are appropriately added, and the paper machine is not limited. There are no particular limitations on the papermaking conditions of the base paper. As the paper machine, for example, a commercial paper machine such as a long paper machine, a gap former paper machine, a circular paper machine, or a short paper machine can be selected and used as appropriate according to the purpose. .

  The newspaper for offset printing of the present invention has a blue or purple dye or colored pigment, fluorescent dye, thickener, water retention agent, antioxidant, antioxidant, as long as the effect of the present invention is not hindered. Various auxiliary agents such as a conductive treatment agent, an antifoaming agent, an ultraviolet absorber, a dispersant, a pH adjuster, a mold release agent, a water-resistant agent, and a water repellent agent can be appropriately blended.

  In the present invention, a surface treating agent can be applied to improve the surface strength. There is no particular limitation on the surface treatment agent, and starch, starch derivatives, water-soluble resins, water-dispersible resins, etc. can be used as adhesives. For example, starch such as corn, potato, tapioca, wheat, rice, etc. and oxidation of the above starch Examples thereof include starch derivatives such as starch, dialdehyde starch, phosphoric acid-modified starch and cationized starch, synthetic water-soluble binders such as polyacrylamide resins and polyvinyl alcohol, and copolymer latexes such as styrene-butadiene copolymers. The polyacrylamide resin has a molecular weight of about tens of thousands to 2,000,000, and is a polymer of acrylamide, a polymer of methacrylamide, a copolymer of acrylamide and methacrylamide, or a polymer or copolymer of these. Examples thereof include a polymer obtained by partially hydrolyzing and partially methylolizing the coalescence. Among them, a polyacrylamide resin is preferably used because it has good Nepari property and is inexpensive and has a starch or starch derivative and good surface strength.

  Adding a surface sizing agent such as a styrene-acrylic acid copolymer or a styrene-maleic acid copolymer to the adhesive in an amount of 1 to 50% by mass is also appropriately performed for the purpose of improving the surface size. For the purpose of improving opacity, it is also effective to add pigments such as calcium carbonate, kaolin, white carbon, amorphous silica, titanium oxide, and plastic pigment at a ratio of 200% by mass or less based on the adhesive. In addition, the range of 30-100 mass% is preferable for the adhesive agent chosen from starch, a starch derivative, or a polyacrylamide type resin with respect to the surface treatment agent total solid.

The surface treatment agent thus obtained is applied on the base paper of printing newsprint in a solid content concentration range of 2% to 15%, but the coating amount is generally 0.05 to 2 g / side. m ^2, preferably applied in the range of 0.1 to 1 g / ^{m 2.} Hardly sufficient surface strength can not be obtained if the coating amount is less than ^{0.05g / m 2, 2g / m} 2 increase exceeds the Neppari strength and undesirably to cause sticking problems in the blanket.

  The coating apparatus for applying the surface treating agent composition to the newsprint base paper is not particularly limited. For example, an ink line or a vertical two-roll size press, a blade metalling size press, a rod metalling size press. Roll coaters such as gate roll coaters, trailing, flexible, roll applications, fountain applications, short-dwell and other bevel and vent type blade coaters, rod blade coaters, bar coaters, air knife coaters, curtain coaters, spray coaters, A publicly known apparatus such as a gravure coater is appropriately used. In addition, as a method of drying the wet coating layer after apply | coating a surface treating agent composition, various systems, such as vapor | steam drying, gas heater drying, electric heater drying, infrared heater drying, are employable, for example.

  In the production of newsprint for offset printing according to the present invention, after the formation of the coating layer of the surface treatment agent composition, smoothing treatment is performed in various calendar devices. Commonly used calendar devices such as a render, a soft calendar, a gloss calendar, a compact calendar, a mat super calendar, and a mat calendar can be used as appropriate. As the calender finishing conditions, the temperature of the rigid roll, the calender pressure, the number of nips, the roll speed, the paper moisture before the calender, and the like are appropriately selected according to the required quality. Furthermore, the calendar device includes an off type that is different from the coater and an on type that is integrated with the coater, but can be used in either case. The material of the calendar apparatus to be used is a roll which is mirror-finished with a metal or a hard chrome plating on the surface of a rigid roll. As the elastic roll, a roll obtained by molding a resin roll such as urethane resin, epoxy resin, polyamide resin, phenol resin, or polyacrylate resin, cotton, nylon, asbestos, aramid fiber, or the like is appropriately used. It should be noted that it is of course possible to use a suitable combination of a water coating device, an electrostatic humidifying device, a steam humidifying device, etc., for humidity control and humidification of the coated paper after finishing with a calendar.

The offset printing newsprint of the present invention can have a post-printing opacity as high as 91% or more, even if the basis weight is 45 g / m ² or less, due to the effect of the embedded porous filler. The internal bond strength (J.TAPPI No18-2) is 150 J / ^{m 2} or more, preferably for at 170J / ^{m 2} or more, there is no possibility of causing such blurred or out of paper.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the part and% in an example show a mass part and the mass%, respectively. Further, the average particle diameter, specific surface area, pore volume, content of metal compound in the porous filler used in Examples and Comparative Examples, and opacity after printing, surface strength, density, Table 1 shows the results of measurement of ash content in paper, white paper opacity, and internal bond strength by the following methods.

<Average particle size and particle size distribution>
The average particle diameter is a value that is 50% in volume integration as measured by a laser diffraction method using SALD2000J (manufactured by Shimadzu Corporation).
The particle size distribution of the porous filler is indicated by the standard deviation (σ) value.
<Pore diameter and specific surface area>
It measured using the pore sizer 9230 (made by Shimadzu Corp.).
<Content of metal compound in porous filler (as oxide)>
It is the value measured using a fluorescent X-ray analyzer (Spectris PW2404).

<Opacity after printing>
JAPAN TAPPI No. 45. In addition, on the basis of the real rice floor of Example 1, a sample of different rice floor was corrected to 0.6% / US square foot 1 g / m ² .

<Surface strength>
Create a sample mount with the newspaper for offset printing obtained in each of the examples and comparative examples attached, and print ink (paper test SD50 Red BT & K TOKA Co., Ltd.) with an RI printing tester (Meiji Seisakusho). Printing was performed using 0.4 cc, and the degree of picking on the printed surface was visually evaluated. Evaluation was performed by the following five-step evaluation.
5: The strength is very high, there is no practical problem, and the quality is excellent.
4: High strength, practically satisfactory, and excellent quality.
3: The strength is high and there is no practical problem.
2: The strength is slightly inferior and there is a problem in practical use.
1: The strength is remarkably inferior, it is a problem in practical use, and the quality is remarkably inferior.

<Ash content>
Ashing was performed at 525 ° C. based on JIS P 8251.
<Opacity>
Measured according to JIS P 8149.
<Internal bond strength>
J. et al. TAPPI No. It measured according to 18-2.

Example 1
10 parts of softwood kraft pulp, 40 parts of thermomechanical pulp and 50 parts of deinked waste paper pulp were mixed and disaggregated. S. F. (Canadian Standard Freeness) to the pulp slurry, 0.5% of cationized starch (P3Y, manufactured by PIRAAB STARCH Co., Ltd.) per dry dry pulp, and the porous filler A shown in Table 1 as a filler is paper. After adding the medium porous filler content to 3% and adjusting the papermaking pH to 4.5 with a sulfuric acid band, the resulting paper stock was made with an on-top twin-wire paper machine and 40 gm / m2 ² newsprint base papers were obtained.
Next, 100 parts of oxidized corn starch (trade name; Oji Ace A, manufactured by Oji Corn Starch Co., Ltd.), an olefin-based sizing agent (trade name; OT-) are coated on both sides of the above-mentioned newsprint paper as a coating solution for the surface treating agent composition. 25, manufactured by Arakawa Chemical Industries, Ltd.) Using a gate roll coater, a mixed aqueous solution having a solid content concentration of 8.8% consisting of 10 parts is 0.39 g / m ² per side after drying. Thus, after applying and drying, a soft calender finish comprising a resin roll / metal roll was performed to obtain an offset printing newsprint with an actual amount of 40.7 g / m ² .

Example 2
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler B was used as the filler.

Example 3
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler C was used as the filler.

Example 4
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler D was used as the filler.

Example 5
A newsprint for offset printing was obtained in the same manner as in Example 1 except that the porous filler A was used as the filler and was added so that the content of the porous filler in the paper was 1.0%.

Example 6
A newsprint for offset printing was obtained in the same manner as in Example 1 except that the porous filler A was used as the filler and was added so that the content of the porous filler in the paper was 8.0%.

Example 7
10 parts of softwood kraft pulp, 40 parts of thermomechanical pulp and 50 parts of deinked waste paper pulp were mixed and disaggregated. S. F. (Canadian Standard Freeness) to a pulp slurry prepared by adding 0.5% of cationized starch (P3Y, manufactured by PIRAAB STARCH Co., Ltd.) and 6% of the above porous filler A per anti-dried pulp, sulfuric acid After adjusting the papermaking pH to 4.5 with a band, the obtained paper stock was made with an on-top twin-wire paper machine to obtain a newsprint base paper having a basis weight of 39 g / m ² .
Next, 100 parts of light calcium carbonate (Brilliant S15, manufactured by Shiroishi Kogyo Co., Ltd.) as a pigment on both sides of the above newsprint base paper, and oxidized corn starch gelatinized and dissolved as an adhesive (trade name: Oji Ace A, 50 parts as a solid content (made by Oji Cornstarch Co., Ltd.) and 5 parts as an olefin surface sizing agent (trade name: OT25, manufactured by Arakawa Chemical Industries Co., Ltd.) as a solid content are added as a solid content, and the solid content concentration is 20%. paint was prepared, a gate coating amount after drying using a roll coater is coated to a per side 0.85 g / m ^2, and dried to actual amounts cold offset printing newspaper 40.7 g / m ² Got the paper.

Comparative Example 1
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler E was used as the filler.

Comparative Example 2
Newspaper for offset printing was obtained in the same manner as in Example 1 except that the porous filler F was used as the filler.

Comparative Example 3
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler G was used as the filler.

Comparative Example 4
Newspaper for offset printing was obtained in the same manner as in Example 1 except that the porous filler H was used as the filler.

Comparative Example 5
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler I was used as the filler.

Comparative Example 6
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler J was used as the filler.

Comparative Example 7
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler K was used as the filler.

Comparative Example 8
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that the porous filler L was used as the filler.

Comparative Example 9
A newsprint for offset printing was obtained in the same manner as in Example 1 except that the porous filler A was used as the filler and was added so that the content of the porous filler in the paper was 0.4%.

Comparative Example 10
A newsprint for offset printing was obtained in the same manner as in Example 1 except that porous filler A was used as the filler and the porous filler content in the paper was added to 11%.

Claims (4)

It contains silicon-containing particles formed from silicon dioxide and / or silicate, and 0.1 to 8.0% by mass of a metal compound in terms of oxide with respect to 100% by mass of the silicon-containing particles, and has a specific surface area. 10 to 150 m ² / g, a pore diameter of 0.10 to 0.80 μm, and an average particle diameter of 16 to 40 μm containing 0.5 to 10.0% by mass as a filler in paper. Newspaper for offset printing. The newsprint for offset printing according to claim 1, wherein the internal bond strength (J.TAPPI No. 18-2) is 150 J / m ² or more. The newspaper for offset printing according to claim 1 or 2, wherein the basis weight is 45 g / m ² or less and the opacity after printing is 91% or more. 4. Newsprint paper for offset printing according to any one of claims 1 to 3, characterized in that 50% by mass or more of deinked waste paper pulp is contained in 100% by mass of raw material pulp.