JP2013177723A - Heat-set type offset rotary printing paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide heat-set type offset rotary printing paper that is excellent in a printed surface feeling, opacity, and a suppression effect of heat-set roughening in a drying process after printing, and is further excellent in a wrinkle suppression effect when the paper is a coated paper.SOLUTION: Heat-set type offset rotary printing paper includes: 30 pts.mass or more and 80 pts.mass or less of mechanical pulp having a length weighted average value of 0.5 mm or more and 1.0 mm or less, based on the total pulp solid content of 100 pts.mass as raw material pulp; and 15 pts.mass or more and 40 pts.mass or less of kaolin having an average aspect ratio of 60 or more and 100 or less, and an average particle diameter of 5.0 μm or more and 10 μm or less based on the total pulp solid contend of 100 pts.mass as filler.

Description

  The present invention relates to a heat-set type offset rotary printing paper, more specifically, printing surface feeling, opacity, excellent heat set roughening suppression effect in the drying process after printing, and the coated paper type printing paper The present invention relates to a heat-set type offset rotary printing paper excellent in the effect of suppressing wrinkles.

  In heat-set type offset rotary printing paper, excellent printing surface feeling is required due to the visualization, colorization, and high-grade orientation of printed matter. In addition, for the purpose of reducing transportation costs, there is an increasing demand for weight reduction of printed materials. In reducing the weight of the printed material, it is possible to select a low basis weight coated paper. However, with the weight reduction, the paper thickness also decreases, the opacity of the printed matter decreases, and the appearance may be impaired. For these reasons, a heat-set type offset rotary printing paper excellent in printing surface feeling and opacity is required.

  In addition, heat-set offset rotary printing has a higher printing speed and can save labor in the post-process, and therefore has a much higher productivity than offset sheet-fed printing. However, since hot air drying is performed after printing, there is a problem of heat set roughening which is not seen in offset sheet-fed printing.

  Heat set roughening is a phenomenon in which, after printing, the ink is rapidly dried with infrared rays or a gas burner, so that it floats along the fibers and appears uneven in the image area and the non-image area. When the occurrence of heat set roughening is conspicuous, the appearance of the printed matter is impaired, which becomes a serious problem in practical use. Factors that cause heat set roughening include breaking of fiber-to-fiber bonds, a phenomenon in which the fiber shape is restored from a flat ribbon shape to a cylindrical shape, and release of internal stress.

As a method for suppressing heat set roughening, after broad-leaved trees, more preferably, broad-leaved trees having a cell wall thickness of 4.0 or more and a bulk weight of 450 kg / m ³ or more are subjected to chemical treatment and then beaten. A method of blending mechanical pulp produced by processing has been proposed (see, for example, Patent Document 1). However, since there are not sufficient measures to suppress the bond between fibers, the phenomenon that the fiber shape is restored from a flat ribbon shape to a cylindrical shape, and the release of internal stress, an excellent heat set roughening suppressing effect is not obtained.

  In addition, heat set type offset rotary printing has a problem of wrinkles. The wrinkle is a wrinkle that appears in the width direction of the paper, which is generated when the paper is rapidly dried with infrared rays or a gas burner after printing. The appearance of the printed matter is greatly impaired, which is a serious problem in practice. Some reports have been made on the cause of this occurrence, and a solution has been proposed (see, for example, Patent Document 2). Generally, however, the image area and non-image area in the drying process after printing have been reported. It is known that the difference in shrinkage is related.

  In the printed matter, the image area is covered with ink, and moisture in the coated paper is less likely to scatter than the non-image area. For this reason, in the drying process after printing, the non-image portion starts to shrink earlier than the image portion, and wrinkles are generated due to a difference in the amount of contraction between the two. Factors affecting the level of wrinkles include fiber orientation of the base paper, air permeability of the coated paper, moisture in the coated paper, and the like. In general, it is said that the drying shrinkage of fibers is much larger in the width direction than in the flow direction. For this reason, when the fiber orientation is aligned, when the fiber of the base paper shrinks in the drying process after printing, the movement strongly affects the dimensional change of the entire base paper, and the amount of fiber shrinkage increases. The degree of Hijiwa gets worse. Therefore, it is preferable that the fiber orientation is low in order to suppress wrinkles. However, in actual production of coated paper for heat-set offset rotary printing, it is very difficult to make a base paper by reducing the fiber orientation because the productivity is lowered.

  As a method for suppressing wrinkles, a method for controlling the air permeability and some paper properties of coated paper has been proposed (see, for example, Patent Document 3). In addition, a method of applying polyvinyl alcohol or polyalkylene glycol having a specified saponification degree to a base paper has been proposed (see, for example, Patent Documents 4 and 5). However, these methods do not provide a sufficient elbow suppression effect. Further, by reducing the water content of the coated paper at the time of production, it is possible to obtain a wrinkle suppressing effect. However, the effect of high gloss and high smoothness due to calendar finishing becomes extremely thin, and not only an excellent printing surface feeling is not obtained, but also wrinkles and curls due to moisture absorption are concerned. In addition, when the moisture is actually reduced by strong drying, there is a problem that drying energy is required and the manufacturing cost is increased.

  For the above reasons, sufficient technology can be established for heat-set offset rotary printing coated paper with excellent print surface feel, opacity, and heat set roughening suppression effect in the drying process after printing, and excellent wrinkle suppression effect. The current situation is not.

JP 2003-49386 A JP 58-186700 A JP-A-6-57686 JP-A-11-350391 JP 2001-180100 A

  An object of the present invention is to provide a heat-set offset rotary printing coated paper which is excellent in printing surface feel, opacity, heat set roughening suppressing effect in the drying process after printing, and also excellent in wrinkle suppressing effect. is there.

  As a result of diligent research in view of the above, the inventors of the present invention have (1) a heat-set offset rotary printing paper comprising at least a base paper, and a length weighted average value of 0.5 mm or more as a raw material pulp in the base paper. Mechanical pulp of 0 mm or less is contained in 30 parts by weight or more and 80 parts by weight or less in 100 parts by weight of the total pulp solids, and the filler has an average aspect ratio of 60 to 100 and an average particle diameter of 5.0 μm to 10 μm. It came to invent the heat-set type offset rotary printing paper characterized by containing a kaolin 15 to 40 mass parts with respect to 100 mass parts of total pulp solid content.

(2) In the heat-set offset rotary printing paper having at least one coating layer mainly composed of a pigment and an adhesive on at least one side of the base paper of the printing paper, the coating layer has a solid mass of 5 per side. .0g / ^{m 2} or more 20 g / ^{m 2} or less in the range in which the above (1) is a heat-set type offset rotary printing paper according.

  (3) The heat-set offset rotary printing paper according to (1) or (2), wherein the mechanical pulp is a thermomechanical pulp or ground pulp.

  (4) The heat-set offset rotary printing paper according to any one of (1) to (3), wherein the coating layer contains, as a pigment, kaolin in a total pigment solid content of 100 parts by mass of 20 parts by mass or more. is there.

  According to the present invention, at least heat-set offset rotary printing paper composed of a base paper is excellent in printing surface feeling, opacity, and heat set roughening suppression effect in the drying process after printing, and more than one layer on at least one side of the base paper With the coated paper type heat-set type offset rotary printing paper having the above coating layer, it is possible to provide a heat-set type offset rotary printing paper that is also excellent in the effect of suppressing wrinkles.

  Hereinafter, the heat set type offset rotary printing paper comprising at least the base paper of the present invention, and the coated paper type heat set type offset rotary printing paper having one or more coating layers on at least one side of the base paper, This will be described in detail.

  In the present invention, the printing surface feeling refers to the degree of unevenness related to optical suitability such as smoothness and gloss on the coated paper surface, and the degree of unevenness derived from the base paper. The excellent printing surface feeling as used in the present invention means a state in which the coated paper has sufficient smoothness, and uneven glossiness and unevenness derived from the base paper are not conspicuous on the surface of the coated paper.

  In the present invention, the opacity refers to a value measured by a method based on JIS P8149. In the present invention, excellent opacity refers to an opacity value of 88.0% or more. When the opacity value is less than 88.0%, the image area on the front surface is seen through from the back surface, and the appearance of the printed matter is impaired, which is not preferable.

  In the present invention, the effect of suppressing heat set roughening is the effect of making the heat set roughing inconspicuous in the drying process after printing in the image area and the non-image area, which are not easily raised and uneven along the fibers. Say.

  In the present invention, the wrinkle suppressing effect refers to an effect of making the wrinkle inconspicuous because a difference in shrinkage between the image area and the non-image area is unlikely to occur in the drying process after printing.

  The heat-set type offset rotary printing paper of the present invention is a so-called non-coated paper type heat-set type offset rotary printing paper comprising at least a base paper, and at least one coating layer on at least one side of the base paper. However, as a base paper used in the present invention, a mechanical pulp having a length weighted average value of 0.5 mm or more and 1.0 mm or less is used as a raw paper pulp. In 100 parts by mass of total pulp solids, 30 parts by mass or more and 80 parts by mass or less of kaolin having an average aspect ratio of 60 or more and 100 or less and an average particle diameter of 5.0 to 10 μm is used as a filler. It is characterized by containing 15 to 40 parts by mass with respect to 100 parts by mass.

  The present inventors examined the relationship between the length-weighted average value of mechanical pulp and heat set roughening, and beaten the length-weighted average value in a range of 0.5 mm to 1.0 mm in order to reduce the bond between fibers. It has been found that the factors that cause heat set roughening such as the phenomenon of cutting and restoring the fiber shape from a flat ribbon shape to a cylindrical shape are reduced. If the thickness is less than 0.5 mm, the effect of suppressing heat set roughening can be sufficiently obtained, but the paper strength is reduced, and problems such as paper scumming or paper breakage during printing occur, which is a serious problem in practice. If it exceeds 1.0 mm, heat set roughening is conspicuous, the appearance of the printed matter is impaired, and this is a serious problem in practical use.

  In the present invention, the length weighted average value of the mechanical pulp is a value measured with a fiber quality analyzer HiRES FQA (manufactured by Optest Equipment).

  In the present invention, the beating machine for beating the mechanical pulp is not limited as long as the length weighted average value is in the range of 0.5 mm to 1.0 mm, for example, beater, Jordan, Deluxe and double disc refiners can be used. Further, the degree of beating is not limited as long as the length weighted average value is in the range of 0.5 mm to 1.0 mm.

  In this invention, content of this mechanical pulp is the range of 30 to 80 mass parts in 100 mass parts of total pulp solid content. If it is less than 30 parts by mass, excellent opacity cannot be obtained. If it exceeds 80 parts by mass, the paper strength will be reduced, causing problems such as paper smearing and paper breakage at the time of printing, which will be a large practical problem.

  In the present invention, the mechanical pulp is not limited at all, and is, for example, ground pulp, refiner ground pulp, thermomechanical pulp, chemithermomechanical pulp, chemical ground pulp, semi-chemical pulp, and the like. More preferably, if the mechanical pulp is a thermomechanical pulp and ground pulp, more excellent opacity can be obtained.

  In this invention, conventionally well-known paper pulp can be used in the range which does not inhibit desired effects other than this mechanical pulp. Examples include kraft pulp such as softwood bleached kraft pulp and hardwood bleached kraft pulp, waste paper pulp such as newspaper wastepaper deinked pulp, and high quality wastepaper deinked pulp. These may be used alone or in combination.

  In the present invention, the filler contains kaolin having an average aspect ratio of 60 or more and 100 or less and an average particle diameter of 5.0 μm or more and 10 μm or less with respect to 100 parts by mass of the total pulp solid content. As a result, it was found that the fiber of mechanical pulp was covered and solidified by kaolin, and an excellent effect of suppressing heat set roughening was obtained. Moreover, it discovered that the smoothness of a base paper improved and the coating surface of the coating liquid improved, and the outstanding printing surface feeling is acquired.

  Furthermore, when the kaolin is contained as a filler, the air permeability of the base paper is lowered, and the air permeability of the resulting coated paper is also lowered. Thereby, the shrinkage | contraction difference of an image part and a non-image part becomes small at the drying process after printing, and the excellent crease suppression effect is acquired.

  In the present invention, when the average aspect ratio of the kaolin is less than 60, sufficient opacity cannot be obtained. Further, the air permeability of the base paper is increased, and an excellent crease suppressing effect cannot be obtained. If it exceeds 100, the fiber-to-fiber bond between the pulp fibers is hindered, and problems such as paper scumming and paper breakage during printing occur, which is a serious problem in practice.

  In the present invention, the average aspect ratio is determined by observing a cross section of the coated paper with a scanning electron microscope (product name: JSM-6930LA, manufactured by JEOL Ltd.) and measuring the aspect ratio of 50 arbitrary kaolin particles contained in the base paper ( (= Value obtained by dividing particle diameter by thickness) was taken as the average aspect ratio.

  In the present invention, when the average particle size of the kaolin is less than 5.0 μm, excellent printing surface feeling, heat set roughening suppressing effect, and wrinkle suppressing effect cannot be obtained. When the thickness exceeds 10 μm, interfiber bonding between pulp fibers is hindered, and problems such as paper scumming or paper breakage during printing occur, which is a large practical problem.

  In the present invention, the average particle diameter is a cumulative average diameter (Median diameter) measured by a laser diffraction method, and can be measured using, for example, Microtrac 3000 II (manufactured by Nikkiso Co., Ltd.).

  In the present invention, when the content of the kaolin is less than 15 parts by mass, excellent printing surface feeling, heat set roughening suppressing effect, and wrinkle suppressing effect cannot be obtained. When the amount exceeds 40 parts by mass, the interfiber bonding between the pulp fibers is hindered, and problems such as paper scumming or paper breakage during printing occur, which is a large practical problem.

  In the present invention, the kaolin is a clay containing at least one kaolin mineral such as kaolinite, halloysite, dickite, or nacrite. If the average aspect ratio is in the range of 60 to 100 and the average particle diameter is in the range of 5.0 μm to 10 μm, conventionally known kaolin can be used in the paper industry. The method of incorporating into the base paper can be achieved by adding the kaolin to the stock.

  In the present invention, the base paper can contain conventionally known papermaking fillers as long as the desired effect other than kaolin is not impaired. For example, calcium carbonate, magnesium carbonate, talc, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, synthetic amorphous silica, colloidal silica, cation Modified colloidal silica, aluminum hydroxide, alumina, alumina hydrate, lithopone, zeolite, hydrohalosite, magnesium hydroxide and other inorganic pigments, styrene plastic pigment, acrylic plastic pigment, polyethylene, urea resin, melamine resin, etc. Is an organic pigment. A plurality of these papermaking fillers may be used in combination. The method of incorporating into the base paper can be achieved by adding these papermaking fillers to the paper stock.

  In the present invention, the papermaking aid contained in the base paper is not limited in any way. For example, as a dry paper strength enhancer, starch, polyacrylamide resin, galactomannan, etc., wet strength strength enhancer As polyamide polyamine epichlorohydrin resin, as sizing agent, alkyl ketene dimer, alkenyl or alkyl succinic anhydride, fatty acid metal salt, fatty acid, epoxy-based higher fatty acid amide, rosin derivative, etc., fixing agent as aluminum chloride, sulfate band, etc. Examples of the pH adjusting agent such as water-soluble aluminum salt of sodium hydroxide, sodium carbonate, sulfuric acid, hydrochloric acid, and the like, as well as a yield improver, a dye, and a fluorescent brightener. These may be used alone or in combination. The method of adding to the base paper can be achieved by adding these papermaking aids to the stock.

  In the present invention, the paper machine for making the base paper is not limited in any way, for example, a long paper machine, a twin wire paper machine, a hybrid paper machine, a circular paper machine, a Yankee paper machine, various combinations. Conventional paper machines known in the paper industry such as paper machines can be used. Further, the paper making speed is not limited at all. The base paper is provided with various size presses, roll coaters, etc. on the paper machine, and coated with various surface treatments such as various starches, resins such as polyvinyl alcohols, polyacrylamide, and other conventionally known surface sizing agents. It doesn't matter. If necessary, auxiliary agents such as antifoaming agents, thickeners, preservatives can be added to the surface treatment agent. Further, various calendar processes such as a machine calendar may be performed in order to obtain the required density and smoothness of the base paper.

  In the present invention, in the heat-set type offset rotary printing paper comprising the base paper, excellent printing surface feeling, opacity, and heat-set roughening suppressing effect can be obtained. Further, on at least one side of the base paper, as a layer not containing a pigment, various copolymer latexes such as styrene / butadiene, acrylic and vinyl acetate, polyvinyl alcohol, sodium polyacrylate, polyethylene oxide, polyacrylamide, Water soluble compounds such as urea or melamine / formalin resin, polyamine polyamide / epichlorohydrin, oxidized starch, cationized starch, urea phosphated starch, etherified starch such as hydroxyethyl etherified starch, various starches such as dextrin, casein Desirable effects can be obtained by providing layers of natural products such as soybean protein and those obtained by cationizing them. The method for providing these layers is not limited at all, and examples thereof include a blade coater, an air knife coater, a rod coater, a curtain coater, a spray coater, and various film transfer coaters such as a size press, a gate roll, and a shim sizer. Can be mentioned.

Furthermore, a coating layer mainly composed of pigment and adhesive on at least one surface of the base paper have one or more layers, a solid per coating coating layer on one side content mass 5.0 g / m ² or more 20 g / m ² By providing the coating amount in the following range, in addition to excellent printing surface feeling, opacity, and heat set roughening suppressing effect, an excellent wrinkle suppressing effect can also be obtained. If the solid content mass per side of the coating layer is less than 5.0 g / m ² , the effect of suppressing wrinkles may be reduced. If it exceeds 20 g / m ² , it is necessary to increase the concentration in order to secure the coating amount, but this increases the viscosity of the coating liquid, and a uniform coating surface cannot be obtained, resulting in a decrease in printing surface feeling. There is a case. However, even if the coating layer is outside the range of the solid content mass of 5.0 g / m ² or more and 20 g / m ² or less per side, the desired effect can be sufficiently obtained in the heat-set offset rotary printing paper.

  The pigment contained in the coating layer is not limited at all, for example, various heavy calcium carbonates, various light calcium carbonates, flat inorganic pigments (kaolin clay, mica, talc, plate barium sulfate, Plate-like magnesium hydroxide, etc.). These may be used alone or in combination. Furthermore, as other pigments, satin white, lithopone, titanium dioxide, alumina, aluminum hydroxide, zinc oxide, magnesium carbonate, natural silica, dry synthetic silica, wet synthetic silica, organic pigments, or those obtained by cation modification, Alternatively, these two or more composites may be used in combination.

  In the present invention, it is more preferable that the coating layer contains 20 parts by mass or more of kaolin as a pigment in 100 parts by mass of the total pigment solid content. If content of this kaolin is 20 mass parts or more, the air permeability of coated paper will become low and a wrinkle suppression effect will improve further. However, even if the content of the kaolin is less than 20 parts by mass, the effect on the present invention is sufficiently obtained. Moreover, the average particle diameter and average aspect ratio of the kaolin are not limited as a pigment, and kaolin conventionally known in the papermaking industry can be used.

  In the present invention, the adhesive contained in the coating layer is not limited at all. For example, various (co) weights such as styrene-butadiene latex, acrylic, polyvinyl acetate, and ethylene-vinyl acetate. Examples include coalesced latex, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, polyethylene oxide, polyacrylamide, urea, melamine and other formalin resins, polyethyleneimine, and polyamide polyamine epichlorohydrin. Furthermore, starch purified from natural plants, hydroxyethylated starch, oxidized starch, etherified starch, phosphate esterified starch, enzyme-modified starch, cold water soluble starch obtained by flash drying them, dextrin, mannan, chitosan, arabi Examples thereof include natural polysaccharides such as nogalactan, glycogen, inulin, pectin, hyaluronic acid, carboxymethylcellulose, and hydroxyethylcellulose, oligomers thereof, and modified products thereof. Examples thereof include natural proteins such as casein, gelatin, soybean protein, collagen, and modified products thereof, and synthetic polymers and oligomers such as polylactic acid and peptides. These may be used alone or in combination. Moreover, in this invention, the compounding quantity of the adhesive agent contained in a coating layer is not restrict | limited at all.

  In the present invention, the coating layer may be a conventional thickener, dispersant, antifoaming agent, surfactant, pH adjuster, water resistant agent, colorant, etc., if necessary, in addition to the pigment and adhesive. A known coating aid may be included. Moreover, in this invention, the compounding quantity of the adjuvant contained in a coating layer is not restrict | limited at all.

  In the present invention, the method for providing a coating layer mainly composed of a pigment and an adhesive is not limited at all. For example, a blade coater, an air knife coater, a rod coater, a curtain coater, a spray coater, or a size press. And various film transfer coaters such as gate rolls and shim sizers.

  In the present invention, the finishing device is not limited at all, and examples thereof include a machine calendar, a soft nip calendar, a super calendar, a multi-stage calendar, a multi-nip calendar, a shoe calendar, and a metal belt calendar.

  The effects of the present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

Example 1
As raw material pulp, 80 parts by weight of chemical ground pulp having a length weighted average value of 0.7 mm and 20 parts by weight of softwood kraft pulp are blended, and as a filler, 30 commercially available kaolins having an average aspect ratio of 80 and an average particle diameter of 8.0 μm are used. A part by mass was blended. In addition to the kaolin, 0.40 parts by mass of a commercially available sulfuric acid band, 0.45 parts by mass of a commercially available cationized starch, 0.12 parts by mass of a commercially available AKD sizing agent, and 0.0175 parts by mass of a commercially available cationic retention agent. A stock was prepared by blending 0.0175 parts by mass of a commercially available anionic retention agent. A mass part here is the solid content mass ratio of each material with respect to 100 mass parts of total pulp solid content. This stock is made using a long paper making machine, and the oxidized starch (product name: MS3800, manufactured by Nippon Shokuhin Kako Co., Ltd.) is 0.60 g / m ^{2 in} terms of solid content per side as a surface treatment agent in the dryer part. As described above, the front and back surfaces were coated by a size press method and then dried to obtain a heat-set offset rotary printing paper of Example 1 having a basis weight of 61.2 g / m ² .

(Example 2)
A heat-set offset rotary printing paper of Example 2 was obtained in the same manner as Example 1 except that the chemical ground pulp of Example 1 was changed to semi-chemical pulp.

(Example 3)
A heat-set offset rotary printing paper of Example 3 was obtained in the same manner as in Example 1 except that the chemical ground pulp of Example 1 was changed to ground pulp.

Example 4
A heat-set offset rotary printing paper of Example 4 was obtained according to Example 1 except that the chemical ground pulp of Example 1 was changed to thermomechanical pulp.

(Example 5)
A heat-set web offset printing paper of Example 5 was obtained in the same manner as Example 1 except that the chemical ground pulp was changed to a content of 30 parts by mass with respect to the total pulp solid content.

(Example 6)
A heat-set web offset printing paper of Example 6 was obtained in the same manner as Example 1 except that the chemical ground pulp was changed to 50 parts by mass with respect to the total pulp solid content.

(Example 7)
A heat-set web offset printing paper of Example 7 was obtained in the same manner as in Example 1 except that the length weighted average value of chemical ground pulp was changed to 0.5 mm.

(Example 8)
A heat-set offset rotary printing paper of Example 8 was obtained in the same manner as in Example 1 except that the length weighted average value of the chemical ground pulp was changed to 1.0 mm.

Example 9
A heat-set web offset printing paper of Example 9 was obtained in the same manner as in Example 1 except that kaolin having an average aspect ratio of 80 used in Example 1 was changed to kaolin adjusted to an average aspect ratio of 60.

(Example 10)
A heatset web offset printing paper of Example 10 was obtained in the same manner as in Example 1 except that kaolin having an average aspect ratio of 80 used in Example 1 was changed to kaolin adjusted to an average aspect ratio of 100.

(Example 11)
Heatset offset web offset printing of Example 11 in the same manner as Example 1 except that kaolin having an average particle size of 8.0 μm used in Example 1 was changed to kaolin having an average particle size adjusted to 5.0 μm. Got the paper.

(Example 12)
The heat-set web offset printing paper of Example 12 was obtained in the same manner as in Example 1 except that kaolin having an average particle diameter of 8.0 μm used in Example 1 was changed to kaolin having an average particle diameter adjusted to 10 μm. Obtained.

(Example 13)
A heat-set offset rotary printing paper of Example 13 was obtained in the same manner as in Example 1 except that the content of kaolin was changed to 15 parts by mass with respect to the total pulp solid content.

(Example 14)
A heat-set offset rotary printing paper of Example 14 was obtained in the same manner as in Example 1 except that the kaolin content was changed to 40 parts by mass relative to the total pulp solid content.

(Example 15)
Example 15 is the same as Example 1 except that the kaolin content is changed to 30 parts by mass with respect to the total pulp solids and the light calcium carbonate content is changed to 10 parts by mass with respect to the total pulp solids. A heat-set type offset rotary printing paper was obtained.

(Example 16)
Example 16 is the same as Example 1 except that the kaolin content is changed to 15 parts by mass with respect to the total pulp solids and the light calcium carbonate content is changed to 25 parts by mass with respect to the total pulp solids. A heat-set type offset rotary printing paper was obtained.

(Example 17)
Heat setting of Example 17 in the same manner as in Example 1 except that the kaolin content was changed to 30 parts by mass with respect to the total pulp solids and the talc content was changed to 10 parts by mass with respect to the total pulp solids. A web offset printing paper was obtained.

(Example 18)
The heat setting of Example 18 except that the kaolin content was changed to 15 parts by mass with respect to the total pulp solids and the talc content was changed to 25 parts by mass with respect to the total pulp solids. A web offset printing paper was obtained.

(Comparative Example 1)
A heat-set offset rotary printing paper of Comparative Example 1 was obtained in the same manner as in Example 1 except that the content of the chemical ground pulp with respect to the total pulp solid content was changed to 20 parts by mass.

(Comparative Example 2)
A heat-set offset rotary printing paper of Comparative Example 2 was obtained in the same manner as in Example 1 except that the content of chemical ground pulp with respect to the total pulp solid content was changed to 90 parts by mass.

(Comparative Example 3)
A heat-set offset rotary printing paper of Comparative Example 3 was obtained in the same manner as in Example 1 except that the length weighted average value of chemical ground pulp was changed to 0.3 mm.

(Comparative Example 4)
A heat-set offset rotary printing paper of Comparative Example 4 was obtained in the same manner as in Example 1 except that the length weighted average value of the chemical ground pulp was changed to 1.2 mm.

(Comparative Example 5)
A heat-set offset rotary printing paper of Comparative Example 5 was obtained in the same manner as in Example 1 except that kaolin having an average aspect ratio of 80 used in Example 1 was changed to kaolin adjusted to an average aspect ratio of 50.

(Comparative Example 6)
A heatset type web offset printing paper of Comparative Example 6 was obtained in the same manner as in Example 1 except that the kaolin having an average aspect ratio of 80 used in Example 1 was changed to a kaolin adjusted to an average aspect ratio of 110.

(Comparative Example 7)
Heatset offset web offset printing of Comparative Example 7 in the same manner as in Example 1 except that kaolin having an average particle size of 8.0 μm used in Example 1 was changed to kaolin having an average particle size adjusted to 4.5 μm. Got the paper.

(Comparative Example 8)
Heatset type offset rotary printing of Comparative Example 8 in the same manner as in Example 1 except that kaolin having an average particle size of 8.0 μm used in Example 1 was changed to kaolin having an average particle size adjusted to 10.5 μm. Got the paper.

(Comparative Example 9)
A heat-set web offset printing paper of Comparative Example 9 was obtained in the same manner as in Example 1 except that the kaolin content was changed to 5 parts by mass with respect to the total pulp solid content.

(Comparative Example 10)
A heat-set offset rotary printing paper of Comparative Example 10 was obtained in the same manner as in Example 1 except that the kaolin content was changed to 50 parts by mass with respect to the total pulp solid content.

(Comparative Example 11)
In the same manner as in Example 1 except that the content of kaolin was changed to 5 parts by mass with respect to the total pulp solids and the content of light calcium carbonate was changed to 35 parts by mass with respect to the total pulp solids, Comparative Example 11 A heat-set type offset rotary printing paper was obtained.

(Comparative Example 12)
Heat setting of Comparative Example 12 in the same manner as in Example 1 except that the content of kaolin was changed to 5 parts by mass with respect to the total pulp solids and the content of talc was changed to 35 parts by mass with respect to the total pulp solids. A web offset printing paper was obtained.

(Evaluation method)
The offset type printing paper produced above was evaluated based on the following evaluation method.
<Opacity>
JIS P 8149 Measured according to the method specified in the ISO 2471 standard published in 1998 as the third edition for the opacity test method (backing of paper) of paper and paperboard with diffuse illumination / 0 ° light reception. Was evaluated as follows. However, in the present invention, three or more points are the subject of the invention.
5 points: The opacity value is 90.0% or more.
4 points: The opacity value is 87.5% or more and less than 90.0%.
3 points: The opacity value is 85.0% or more and less than 87.5%.
2 points: The opacity value is 82.5% or more and less than 85.0%.
1 point: The opacity value is less than 82.5%.

<Tensile strength>
Based on ISO 1924-2 issued as the second edition in JIS P8113 in 1994, using a constant speed extension type tensile tester in accordance with the Japanese Industrial Standard created without changing the technical contents and the configuration of the corresponding international standard, The tensile strength, tensile elongation at break, and tensile energy absorption amount of the paperboard, and the specific tensile strength, specific tensile energy absorption amount, and calculation method of the tensile modulus were measured according to the prescribed methods. The tensile strength was evaluated as follows. However, in the present invention, three or more points are the subject of the invention.
5 points: The value of tensile strength is 4.0 kN / m or more.
4 points: The tensile strength value is 3.5 kN / m or more and less than 4.0 kN / m.
3 points: The tensile strength value is 3.0 kN / m or more and less than 3.5 kN / m.
2 points: The value of tensile strength is 2.5 kN / m or more and less than 3.0 kN / m.
1 point: The value of tensile strength is 2.0 kN / m or more and less than 2.5 kN / m.

<Print durability>
Using an offset rotary printing press (Mitsubishi Heavy Industries, Ltd., Lithopia BT-2-600), offset rotary printing ink (Dainippon Ink Chemical Industries, Web World Terrace N, black, indigo, red, yellow) ) Was used at a printing speed of 700 rpm, and the degree of accumulation of paper dust on the black blanket was visually evaluated. However, in the present invention, ◯ or Δ is the subject of the invention.
○: Generation of paper dust was not recognized.
Δ: Some generation of paper dust was observed.
X: A lot of paper dust was accumulated.

<Heat set roughening>
Offset rotary printing press (Mitsubishi Heavy Industries, Ltd., Lithopia BT-2-600 type), offset rotary printing ink (Dainippon Ink Chemical Industries, Web World Terrace N, black, indigo, red, yellow) ) Was used at a printing speed of 700 rpm, and the unevenness of the printed surface after 24 hours was observed and evaluated. The degree of roughening is shown below. However, in the present invention, three or more points are the subject of the invention.
5 points: Floating along the fiber on the printed surface and no irregularities.
4 points: Slightly raised along the fiber.
3 points: Float along the fiber on the printed surface, and unevenness is seen, but it does not feel rough.
2 points: A feeling of roughness is felt when viewing the printed matter.
1 point: The fiber floats up, the unevenness is clearly seen, and it feels rough.

  The heat-set type offset rotary printing paper obtained in Examples and Comparative Examples was evaluated by the above evaluation method, and the results are shown in Tables 1 and 2.

<Comprehensive evaluation>
Comparing Examples 1, 5, and 6 with Comparative Examples 1 and 2, heat set offset excellent in opacity and tensile strength by containing chemical ground pulp in an amount of 30 to 80 parts by mass of the total pulp solid content Rotary printing paper can be provided.

  When Examples 7 and 8 were compared with Comparative Examples 3 and 4, the opacity and tensile strength were not reduced by refining and adjusting the length weighted average value of 0.5 mm to 1.0 mm as a pulp component, and heat setting It can be seen that roughening is suppressed.

  When Examples 9, 10, 11, 12, 13, 14 and Comparative Examples 5, 6, 7, 8, 9, 10 were compared, the average aspect ratio was 60 or more and 100 or less, and the average particle size was 5.0 μm or more and 10 μm or less. It can be seen that containing 15 parts by weight or more and 40 parts by weight or less of kaolin with respect to the pulp component can improve opacity and reduce heat set roughening without impairing printing durability.

  When Examples 15, 16, 17, and 18 and Comparative Examples 11 and 12 are compared, kaolin having an average aspect ratio of 60 to 100 and an average particle size of 5.0 to 10 μm is included rather than containing light calcium carbonate or talc. It can be seen that the inclusion improves opacity and suppresses the occurrence of heat set roughing.

(Example 19)
<Base paper>
As raw material pulp, 80 parts by weight of chemical ground pulp having a length weighted average value of 0.7 mm and 20 parts by weight of softwood kraft pulp are blended, and as a filler, 30 commercially available kaolins having an average aspect ratio of 80 and an average particle diameter of 8.0 μm are used. A part by mass was blended. In addition to the kaolin, 0.40 parts by mass of a commercially available sulfuric acid band, 0.45 parts by mass of a commercially available cationized starch, 0.12 parts by mass of a commercially available AKD sizing agent, and 0.0175 parts by mass of a commercially available cationic retention agent. The same stock material as in Example 1 was prepared by blending 0.0175 parts by mass of a commercially available anionic retention agent. This stock is made using a long paper making machine, and the oxidized starch (product name: MS3800, manufactured by Nippon Shokuhin Kako Co., Ltd.) is 0.60 g / m ^{2 in} terms of solid content per side as a surface treatment agent in the dryer part. As described above, the front and back surfaces were coated by a size press method and dried to obtain a base paper having a basis weight of 61.2 g / m ² .

<Coating fluid>
A coating solution for providing a coating layer on the base paper was prepared as follows. A mass part here is a solid content mass ratio with respect to 100 mass parts of the total pigment solid content in a coating liquid. To 50 parts by mass of commercially available wet heavy calcium carbonate and 50 parts by mass of commercially available primary kaolin, 0.10 parts by mass of a commercially available polyacrylic dispersant is added and dispersed at a solid concentration of 72% by mass as an adhesive. , 10 parts by mass of commercially available styrene-butadiene copolymer latex, 4.0 parts by mass of commercially available phosphoric esterified starch, 0.50 parts by mass of commercially available calcium stearate, and adjusted to pH 9.6 with sodium hydroxide, A coating solution was obtained. The obtained coating liquid was adjusted to a solid concentration of 52% by mass with adjusted water.

<Coating / Finish>
Using the blade coater, apply the above coating liquid to the above base paper under the conditions of an operation speed of 200 m / min, a solid content coating amount of 10 g / m ² per side, and 20 g / m ^{2 on} both sides. And dried. The obtained coated paper was used with a soft calendar composed of a metal roll (hardness Hs 84 degrees, surface roughness 0.3 S) heated to 60 ° C. and an elastic roll (hardness 90 ShD, product name: Elaglass 90, manufactured by Kinyo). Then, a heat-set offset rotary printing paper of Example 19 was obtained by applying a pressure condition of 80 kN / m and treating the surface of the metal roll once each on the front and back sides.

(Example 20)
In Example 19, a heat-set offset rotary printing paper of Example 20 was obtained in the same manner as Example 19 except that the chemical ground pulp was changed to semi-chemical pulp.

(Example 21)
In Example 19, a heat-set offset rotary printing paper of Example 21 was obtained in the same manner as Example 19 except that the chemical ground pulp was changed to ground pulp.

(Example 22)
In Example 19, except that the chemical ground pulp was changed to thermomechanical pulp, the heat-set type offset rotary printing paper of Example 22 was obtained in the same manner as Example 19.

(Example 23)
In Example 19, except that the content of chemical ground pulp was changed to 30 parts by mass and the content of softwood kraft pulp was changed to 70 parts by mass, everything was the same as Example 19, and the heat-set offset rotary press of Example 23 was performed. I got printing paper.

(Example 24)
In Example 19, except that the content of the chemical ground pulp was changed to 50 parts by mass and the content of the softwood kraft pulp was changed to 50 parts by mass, everything was the same as Example 19, and the heat-set offset rotary press of Example 24 was performed. I got printing paper.

(Example 25)
In Example 19, a heat-set offset rotary printing paper of Example 25 was obtained in the same manner as Example 19 except that the length weighted average value of the chemical ground pulp was changed to 0.5 mm.

(Example 26)
In Example 19, a heat-set offset rotary printing paper of Example 26 was obtained in the same manner as in Example 19 except that the length weighted average value of the chemical ground pulp was changed to 1.0 mm.

(Example 27)
In Example 19, except that kaolin having an average aspect ratio of 80 was changed to kaolin having an average aspect ratio of 60 as a filler, the heatset type web offset printing paper of Example 27 was obtained in the same manner as in Example 19. .

(Example 28)
In Example 19, except that kaolin having an average aspect ratio of 80 was changed to kaolin having an average aspect ratio of 100 as a filler, the heatset type offset rotary printing paper of Example 28 was obtained in the same manner as in Example 19. .

(Example 29)
In Example 19, except that kaolin with an average particle size of 8.0 μm was changed to kaolin with an average particle size of 5.0 μm as a filler, the same as in Example 19 and the heat-set offset rotary printing of Example 29 Got the paper.

(Example 30)
In Example 19, the heat-set offset rotary printing paper of Example 30 was obtained in the same manner as in Example 19 except that kaolin having an average particle diameter of 8.0 μm was changed to kaolin having an average particle diameter of 10 μm as the filler. It was.

(Example 31)
In Example 19, the heat-set offset rotary printing paper of Example 31 was obtained in the same manner as Example 19 except that the kaolin content was changed to 15 parts by mass as a filler.

(Example 32)
In Example 19, the heat-set offset rotary printing paper of Example 32 was obtained in the same manner as in Example 19 except that the content of kaolin was changed to 40 parts by mass as a filler.

(Example 33)
In Example 19, the heat-set offset of Example 33 was used in the same manner as in Example 19 except that the kaolin content was changed to 30 parts by mass and the light calcium carbonate content was changed to 10 parts by mass. A rotary printing paper was obtained.

(Example 34)
In Example 19, the heat-set offset of Example 34 was used in the same manner as Example 19 except that the kaolin content was changed to 15 parts by mass and the light calcium carbonate content was changed to 25 parts by mass. A rotary printing paper was obtained.

(Example 35)
In Example 19, except that the content of kaolin was changed to 30 parts by mass and the content of talc was changed to 10 parts by mass, the same as Example 19, except that the heat-set offset web offset printing of Example 35 was used. Got the paper.

(Example 36)
In Example 19, the heat-set web offset printing of Example 36 was performed in the same manner as in Example 19 except that the content of kaolin was changed to 15 parts by mass and the content of talc was changed to 25 parts by mass. Got the paper.

(Example 37)
In Example 19, the heat-set mold of Example 37 was the same as Example 19 except that the solid content coating amount per side was changed to 5.0 g / m ² and both sides were changed to 10.0 g / m ^2. An offset rotary printing paper was obtained.

(Example 38)
In Example 19, except that the solid content coating amount per side was changed to 20 g / m ² and 40 g / m ² on both sides, the same heat-set offset rotary printing paper of Example 38 was used as in Example 19. Got.

(Example 39)
In Example 19, the heat-set offset rotary printing of Example 39 was performed in the same manner as Example 19 except that the content of the commercially available primary kaolin was changed to 20 parts by mass as the pigment contained in the coating liquid. Got the paper.

(Example 40)
In Example 19, the heat-set offset rotary printing of Example 40 was performed in the same manner as Example 19 except that the content of the commercially available primary kaolin was changed to 10 parts by mass as the pigment contained in the coating liquid. Got the paper.

(Example 41)
In Example 19, the heat-set type of Example 41 was the same as Example 19 except that the solid content coating amount per side was changed to 4.0 g / m ² and 8.0 g / m ² on both sides. An offset rotary printing paper was obtained.

(Example 42)
In Example 19, except that the solid content coating amount on one side was changed to 21 g / m ² and 42 g / m ² on both sides, the same heat-set offset rotary printing paper of Example 42 was used as in Example 19. Got.

(Comparative Example 13)
In Example 19, except that the content of chemical ground pulp was changed to 20 parts by mass, and the content of softwood kraft pulp was changed to 80 parts by mass, the same as Example 19 was carried out, and the heat-set offset rotary press of Comparative Example 13 was performed. I got printing paper.

(Comparative Example 14)
In Example 19, except that the content of chemical ground pulp was changed to 90 parts by mass and the content of softwood kraft pulp was changed to 10 parts by mass, the same heat-set offset rotary rotation of Comparative Example 15 as in Example 19 I got printing paper.

(Comparative Example 15)
In Example 19, except that the length weighted average value of the chemical ground pulp was changed to 0.3 mm, the heat-set offset rotary printing paper of Comparative Example 15 was obtained in the same manner as Example 19.

(Comparative Example 16)
In Example 1, except that the length weighted average value of the chemical ground pulp was changed to 1.2 mm, the heatset type offset rotary printing paper of Comparative Example 16 was obtained in the same manner as Example 19.

(Comparative Example 17)
In Example 19, as a filler, except that kaolin having an average aspect ratio of 80 was changed to kaolin having an average aspect ratio of 50, heat-set offset rotary printing paper of Comparative Example 17 was obtained in the same manner as in Example 19. .

(Comparative Example 18)
In Example 19, as a filler, except that kaolin having an average aspect ratio of 80 was changed to kaolin having an average aspect ratio of 110, the heatset type offset rotary printing paper of Comparative Example 18 was obtained in the same manner as Example 19. .

(Comparative Example 19)
In Example 19, except that kaolin with an average particle size of 8.0 μm was changed to kaolin with an average particle size of 4.5 μm as a filler, the same as in Example 19 and the heat-set offset rotary printing of Comparative Example 19 Got the paper.

(Comparative Example 20)
In Example 19, except that kaolin having an average particle size of 8.0 μm was changed to kaolin having an average particle size of 10.5 μm as a filler, the same heat-set offset rotary printing of Comparative Example 20 as in Example 19 Got the paper.

(Comparative Example 21)
In Example 19, a heat-set offset rotary printing paper of Comparative Example 21 was obtained in the same manner as Example 19 except that the kaolin content was changed to 5 parts by mass as a filler.

(Comparative Example 22)
In Example 19, a heat-set offset rotary printing paper of Comparative Example 22 was obtained in the same manner as in Example 19 except that the kaolin content was changed to 50 parts by mass as a filler.

(Comparative Example 23)
In Example 19, the heat-set offset of Comparative Example 23 was used in the same manner as Example 19 except that the kaolin content was changed to 5 parts by mass and the light calcium carbonate content was changed to 35 parts by mass. A rotary printing paper was obtained.

(Comparative Example 24)
In Example 19, except that the content of kaolin was changed to 5 parts by mass and the content of talc was changed to 35 parts by mass, the same as Example 19, except that the heat-set offset web offset printing of Comparative Example 24 was used. Got the paper.

  Evaluation of the heatset type offset rotary printing paper in Examples 19 to 42 and Comparative Examples 13 to 24 was performed by the following method.

  As a printed matter for evaluation, in the heat-set type offset rotary printing paper in Examples 19 to 42 and Comparative Examples 13 to 24, an offset rotary press (product name: lithopia BT-2-600, manufactured by Mitsubishi Heavy Industries, Ltd.), offset ring Using diverted printing ink (product name: Web World Terrace N black, indigo, red, yellow, manufactured by Dainippon Ink & Chemicals, Inc.), a solid print was produced only on the surface.

<Print surface>
The image area and non-image area of the evaluation printed material were visually judged and evaluated. The evaluation criteria are shown below. However, in the present invention, three or more points are the subject of the invention. It should be noted that when a problem such as paper smearing or paper breakage at the time of printing due to a decrease in paper strength occurs, the score is 0, and there is a large practical problem.
5 points: The coated paper has sufficient smoothness, and uneven glossiness and unevenness derived from the base paper are inconspicuous at all on the coated paper surface.
4 points: The coated paper has sufficient smoothness and slight unevenness of gloss is seen on the surface of the coated paper, but the unevenness derived from the base paper is inconspicuous at all.
3 points: The coated paper has sufficient smoothness, and uneven gloss and slight irregularities derived from the base paper are seen on the coated paper surface, but none of them is conspicuous.
Two points: Smoothness of coated paper is insufficient, and uneven glossiness and unevenness derived from the base paper are conspicuous on the coated paper surface.
1 point: The smoothness of the coated paper is insufficient, uneven glossiness and irregularities derived from the base paper are very conspicuous on the coated paper surface, and the appearance of the printed matter is impaired.

<Opacity>
Based on JIS P8149, the opacity of the heat-set offset rotary printing coated paper was measured using SPECTRO COLORMETER MODEL PF-10 (manufactured by Nippon Denshoku Industries Co., Ltd.). The evaluation criteria are shown below. However, in the present invention, three or more points are the subject of the invention.
5 points: The opacity value is 94.0% or more.
4 points: The opacity value is 91.0% or more and less than 94.0%.
3 points: The value of opacity is 88.0% or more and less than 91.0%.
2 points: The opacity value is 85.0% or more and less than 88.0%.
1 point: The opacity value is less than 85.0%.

<Heat set roughening>
The image area and non-image area of the evaluation printed material were visually judged and evaluated. The evaluation criteria are shown below. However, in the present invention, three or more points are the subject of the invention.
5 points: In the state where the image area and the non-image area are lifted along the fiber and no unevenness is observed.
4 points: Floating along the fibers and slight irregularities are seen in the image area and the non-image area, but their degree is extremely small and inconspicuous.
3 points: Floating along the fibers and irregularities are seen in the image area and the non-image area, but their degree is small and inconspicuous.
Two points: In the image area and the non-image area, floating along the fibers and irregularities are observed, but the degree of them is large and is conspicuous.
1 point: Floating along the fiber and unevenness are very conspicuous in the image area and the non-image area, and the appearance of the printed matter is impaired.

<Hijiwa>
The wrinkles generated in the image area of the evaluation printed matter were visually judged and evaluated. The evaluation criteria are shown below. However, in the present invention, three or more points are the subject of the invention.
5 points: Hijiwa is inconspicuous.
4 points: Slight bulges are seen but inconspicuous.
3 points: Hijiwa is seen, but the degree is sufficiently small and inconspicuous.
Two points: Although wrinkles are seen, the extent is large and the appearance of printed matter is impaired.
1 point: Hijiwa is conspicuous, has a great influence not only on the appearance of the printed matter but also on the shape of the printed matter.

  Table 3 shows the evaluation results of Examples 19 to 42 and Comparative Examples 13 to 24.

  As is clear from the evaluation results in Table 3, from the comparison between Examples 19, 23 and 24 and Comparative Examples 13 and 14, the chemical ground pulp was 30 parts by mass or more and 80 parts by mass or less in 100 parts by mass of the total pulp solid content. It can be seen that, by adding it, excellent printing surface feeling, opacity, heat set roughening suppressing effect, and wrinkle suppressing effect are obtained, and when the content of chemical ground pulp is increased, the opacity is improved. Further, from the comparison between Examples 25 and 26 and Comparative Examples 15 and 16, by refining the chemical ground pulp to a length weighted average value of 0.5 mm to 1.0 mm, excellent printing surface feeling, opacity, It can be seen that a heat set roughening suppressing effect and a wrinkle suppressing effect can be obtained.

  From a comparison between Examples 27 to 32 and Comparative Examples 17 to 22, kaolin having an average aspect ratio of 60 to 100 and an average particle size of 5.0 to 10 μm is 15 parts by mass with respect to 100 parts by mass of pulp solid content. It turns out that the outstanding printing surface feeling, opacity, the heat set roughening inhibitory effect, and a wrinkle inhibitory effect are acquired by containing more than 40 parts by mass. Further, from the comparison between Examples 33 to 36 and Comparative Examples 23 and 24, as the filler, when the content of kaolin is increased with respect to light calcium carbonate and talc, printing surface feeling, opacity, heat set roughening suppressing effect, It can be seen that the effect of suppressing the wrinkle improves.

Moreover, from the evaluation results of Examples 19, 37, 38, 41, and 42, the coating layer mainly composed of the pigment and the adhesive has a solid content mass of 5.0 g / m ² or more and 20 g / m ² or less on one side. It can be seen that an excellent printing surface feel, opacity, heat set roughening suppressing effect, and wrinkle suppressing effect can be obtained by providing the coating amount within the range.

  From comparison between Examples 19 and 20 and Examples 21 and 22, it can be seen that if the type of mechanical pulp is thermomechanical pulp or ground pulp, more excellent opacity can be obtained.

  From the evaluation results of Examples 19, 39, and 40, when the coating layer contains kaolin as a pigment in an amount of 20 parts by mass or more in 100 parts by mass of the total pigment solid content, a more excellent effect is obtained with respect to the effect of suppressing wrinkles. It can be seen that it is preferable.

Claims (4)

  In heat-set offset rotary printing paper, as a raw material pulp, length-weighted average value of 0.5 mm to 1.0 mm mechanical pulp containing 100 parts by mass of total pulp solids, containing 30 parts by mass to 80 parts by mass, And as a filler, it contains 15 to 40 parts by mass of kaolin having an average aspect ratio of 60 to 100 and an average particle size of 5.0 to 10 μm with respect to 100 parts by mass of the total pulp solid content. Heat set offset rotary printing paper. In the heat-set offset rotary printing paper having at least one coating layer mainly composed of a pigment and an adhesive on at least one side of the printing paper, the coating layer has a solid content mass of 5.0 g / m ² or more per side. The heat-set type offset rotary printing paper according to claim 1, which is in a range of 20 g / m ² or less.   The heatset type offset rotary printing paper according to claim 1 or 2, wherein the mechanical pulp is a thermomechanical pulp or ground pulp.   The heat-set offset rotary printing paper according to any one of claims 1 to 3, wherein the coating layer contains 20 parts by mass or more of kaolin as a pigment in 100 parts by mass of the total pigment solid content.