JP4940622B2 - Newspaper for cold offset printing - Google Patents

Description

  The present invention can remarkably improve ink fillability and post-print opacity in multi-color printing using a cold offset type printing press, and it also has a Nepali phenomenon, blanket piling, printing press roll stains and set. The present invention relates to news paper for cold offset printing having good printing workability and color printing quality without causing troubles such as off defects.

In recent years, newspaper printing using cold-set offset rotary presses has been rapidly offset, colorized, and speeded up, and has better color printing suitability and printing workability for newspapers that serve as printing media. There is a need for newsprint. In addition, color images such as newspaper advertisements are required to have higher reproducibility. Although the progress of the printing plate manufacturing process and the sharpness of the original image are remarkable, the color and sharpness of the color printed under normal newsprint conditions are significantly inferior to those of ordinary coated paper for printing. , Lacking in appealing power.

Furthermore, recent newspaper papers are required to be lighter, and accordingly, there is an increasing demand for papers that can maintain high opacity after printing. In order to meet this demand, inorganic pigments such as white carbon, calcium carbonate, titanium oxide, and talc have been used as fillers during papermaking in order to improve the opacity of paper. Moreover, although high-rate blending of DIP (deinked waste paper pulp), which is regarded as important in terms of the environment, has progressed, opacity is less likely to occur compared to mechanical pulps such as GP, RGP, and TMP. It is extremely difficult to achieve both improvement in opacity and high rate blending of DIP.

On the other hand, coated paper made by coating a base paper with a paint consisting of pigment and binder at a dry weight of about 8 g / m ² or more and having a good surface property is suitable for multicolor printing. Paper printing uses a printing press with a heat-setting device and oxidative polymerization drying ink, and the ink drying system differs between cold offset printing press and newspaper printing using penetrating drying ink. If the coated paper is printed on a cold offset newspaper rotary press, it may cause troubles related to printing surface quality and printing workability such as set-off failure and smearing that occur when the ink is not sufficiently dried.

As a newsprint for cold offset printing, a technique of providing a coating layer containing a pigment having an oil absorption of 65 cc / or more is disclosed (see Patent Document 1). However, a coating layer containing a large amount of pigment having a high oil absorption tends to have a weak surface strength in a wet state, and easily causes pigment piling on a blanket of a printing press. In addition, the coating layer containing a large amount of pigment with high oil absorption absorbs the vehicle components in the ink rapidly, causing a rapid rise in ink tack on the paper surface, causing high tack ink to adhere to the printing press roll. The paper surface was sometimes stained. In addition, a technique for improving the ink setting suitability and the ink density is disclosed by defining the dynamic wetting value of the base paper and using a combination of kaolin and an irregular pigment having an average particle diameter. The effect of improving the transparency is small, the ink setting becomes slow, and stickiness may occur (see Patent Document 2). In order to obtain high opacity, there are some that disclose the effect of improving whiteness and opacity by applying bulky pigments such as satin white, hydrated silicic acid, and hollow organic pigments. Since it is weak and the blanket piling deteriorates, it is necessary to increase the adhesive ratio. As a result, the effect on the opacity is reduced and the cost is not preferable (see Patent Documents 3, 4, and 5). Although newspaper coated paper using a specific latex and a water-soluble polymer as a binder and an organic pigment as a pigment is disclosed, the organic pigment contributes to improving blank paper opacity, Due to poor ink absorbency, contribution to opacity after printing is low. In addition, when the organic pigment is present on the outermost surface of the paper, wrinkles may occur at a place where friction occurs such as a fixed roll or a fixed sensor (see Patent Document 6). On the other hand, as a technique aimed at improving opacity after printing on a base paper, a technique of applying an external additive such as starch or latex to a base paper containing hydrated silicic acid that satisfies specific particle characteristics is disclosed, These internally added particles have insufficient oil absorption, and the particle diameter range is too small, resulting in a low yield on the paper machine. Furthermore, since the application of external additives reduces opacity and whiteness, it is difficult to obtain newsprint that satisfies high optical requirements (see Patent Document 7).

From the above situation, in cold set type high-speed rotary printing using penetrable ink, the ink setting property is good, the printing workability is excellent, the post-printing opacity is high, and the color multicolor printing. There has been a strong demand for newspaper printing paper having printability with good color reproducibility and sharpness.
Japanese Patent Laid-Open No. 1-174697 Japanese Patent Laid-Open No. 4-57988 JP 2000-34694 A JP 2001-164494 A JP 2000-314097 A JP H02-74698 A Japanese Patent No. 3026933

The present invention can remarkably improve ink fillability and opacity after printing in cold offset printing using penetrable drying ink in a multicolor printing system, and further, such as cosmetic stains and defective set-off. It is an object of the present invention to provide a cold offset newspaper printing paper having good printing workability and color printing quality without causing printing trouble.

The inventors of the present invention diligently studied the influence of the base paper and the surface treatment agent used on the ink setting property and printing workability such as an ink set in cold offset printing. As a result, it is indispensable to give a strong oil absorption capability to the base paper in order to fully exhibit its performance in multicolor printing, and a surface treatment agent containing a pigment mainly composed of calcium carbonate is also required. By applying a small amount, it has been found that both the printing surface suitability and the printing workability can be achieved, and the present invention has been completed.

This application includes the following inventions.
(1) A cold offset printing paper obtained by applying a surface treatment agent mainly composed of a pigment and an adhesive on a base paper, and drying it. 0.5 to 5.0 weight of filler having an oil absorption of 360 to 500 mL / 100 g The surface treatment agent layer having a coating amount of 1.4 g / m ² or less per side and containing 60% by weight or more of calcium carbonate based on the total pigment is provided on the base paper containing 1%, and the basis weight is 50 g / m ^2. A cold offset newsprint having a dynamic friction coefficient of 0.45 to 0.65, whiteness of 54% or more, post-printing opacity of 90% or more, and oil absorption of 60 to 200 seconds.
(2) The integrated capacity of pore diameters in the range of 0.01 to 10 μm is 2.0 to 5.0 mL / g, and the center pore diameter of the pore volume 50% is 0.05 to 0.20 μm. For cold offset printing according to (1), wherein the cumulative capacity of the pore diameter range of 0.01 to 0.1 μm is 1.0 mL / g or more and the average particle diameter by laser method is 15 to 40 μm or less Newspaper.
(3) The newsprint for cold offset printing according to (1) or (2), wherein the amount of adhesive per 100 parts by weight of the pigment of the surface treatment agent is 40 to 150 parts by weight.
(4) The newsprint for cold offset printing according to (1) or (2), wherein the amount of adhesive per 100 parts by weight of the pigment of the surface treatment agent is 40 parts by weight or more and less than 70 parts by weight.
(5) The newsprint for cold offset printing according to any one of (1) to (4), wherein the pigment contains calcium carbonate and kaolin in a ratio of 60:40 to 90:10.
(6) The newsprint paper for cold offset printing according to (5), wherein the average particle diameter of the kaolin by laser method is 2 to 8 μm.
(7) The newsprint for cold offset printing according to any one of (1) to (6), wherein the calcium carbonate is cubic light calcium carbonate.
(8) The adhesive is mainly composed of starch and latex, the ratio of latex to 100 parts by weight of starch is 10 to 100 parts by weight, and the contact angle between the paper surface and water is 0.1 seconds after dropping water. The newsprint for cold offset printing according to any one of (1) to (7), which has a value of 80 ° or more.
(9) The newsprint for cold offset printing according to (8), wherein the latex is a core shell type latex.

The newsprint for cold offset printing according to the present invention can remarkably improve ink fillability and post-print opacity in multicolor printing using a cold offset type rotary printing press. There is an advantage of having good printing workability and color printing quality without causing troubles such as piling, printing press roll dirt, and set-off failure.

In order to provide news paper for cold offset printing with excellent color printing suitability and good printing workability, a filler with an oil absorption of 360 to 500 mL / 100 g in the base paper is 0.5 to 5.0% by weight, Preferably, it should be contained in an amount of 2.0 to 4.5% by weight. A silica-based filler that has a high oil absorption capability and is effective for the opacity effect is preferable. Newspaper paper provided with a surface treatment agent layer generally tends to slow the ink setting. This is because the surface treatment agent covers most of the pores on the surface of the base paper, but the ink set does not deteriorate when the oil absorbing ability of the filler contained in the base paper is strong. In particular, the cumulative volume of pore diameters in the range of 0.01 to 10.0 μm is 2.0 to 5.0 mL / g, and the central pore diameter of the pore volume 50% is in the range of 0.05 to 0.20 μm. Yes, the cumulative capacity in the pore diameter range of 0.01 to 0.1 μm is 1.0 mL / g or more, and the filler having an average particle diameter of 15 to 40 μm or less by the laser method has a high oil absorption capacity and has a set-off trouble. Hard to occur. Of these physical properties, the cumulative capacity in the pore diameter range of 0.01 to 0.1 μm is particularly important. The higher the cumulative capacity in the pore diameter range, the better the ink drying ability. / G or more expresses necessary and sufficient ink absorbing ability. The pore volume and pore diameter of these fillers are values measured using a mercury porosimeter (type: Pore Sizer 9320, manufactured by Micromeritics). When the oil absorption amount is less than 360 mL / 100 g, sufficient oil absorption capacity cannot be obtained. When the oil absorption amount exceeds 500 mL / 100 g, the oil absorption speed is too high, and the ink tack on the printing surface rapidly increases, and the roll on the printing press An ink trail occurs. The oil absorption is a value measured by the method of JISK5101. When the filler content in the base paper is less than 0.5% by weight, the oil absorption capacity is insufficient and a sufficient effect cannot be obtained. On the other hand, if the filler content exceeds 5.0% by weight, a trailer to the printing press blanket is likely to occur, and the oil absorption capacity is too strong to cause a sharp rise in ink tack, causing the roll on the printing press to An ink trail occurs. If the average particle diameter by the laser method is smaller than 15 μm, the yield on the paper machine is deteriorated. When the average particle diameter exceeds 40 μm, filler piling on the printing press blanket becomes intense, and in some cases, the printing surface may be blurred. The average particle size was obtained by measuring the particle size distribution of a filler slurry in which 0.2% by weight of a dispersant was added and mixed with a laser diffraction particle size distribution analyzer (type: SALD-2000, manufactured by Shimadzu Corporation). The median diameter.

The surface treatment agent mainly composed of a pigment and an adhesive needs to have a coating amount of 1.4 g / m ² or less per side. If it exceeds 1.4 g / m ² , problems may occur in printing workability such as set-off. Further, an application amount of less than 0.1 g / m ² is not preferable because an opacity effect is not obtained. As a pigment, it is important to contain calcium carbonate in an amount of 60% by weight or more, more preferably 70 to 90% by weight based on the total pigment. Calcium carbonate includes needles, columns, spheres, spindles, etc. Among them, cubics are preferable because they are effective in ink absorption set-off. Among them, cubic light coal is easy to have a rough structure in the coating layer, has a high ability to absorb the vehicle content in the ink, has a high set-off suppressing effect, and has a structurally easy to express friction coefficient. The smaller the particle diameter of calcium carbonate, the smaller the pore diameter of the coating layer and the larger the specific surface area, which is advantageous for set-off and opacity. Calcium carbonate is highly effective in improving opacity, but tends to increase the coefficient of dynamic friction. In the case of newspapers driven at high speed, if the friction coefficient is low, the web tension is difficult to be applied and there is a risk of causing wrinkles and paper flow. Since there is fear, it is necessary to make a dynamic friction coefficient into the range of 0.45-0.65. The dynamic friction coefficient adjustment method can be adjusted not only by adjusting the pigment coating amount, but also by commonly used lubricants such as fatty acid metal soaps such as zinc stearate and calcium stearate, alkyl ketene dimers, and ethylene compounds. In view of balance with the effect of improving opacity, kaolin is preferably used in combination.

Kaolin is inferior to calcium carbonate in improving opacity, but it absorbs less adhesive than satin, hydrated silicic acid and organic pigments, and has a large effect on surface smoothness. It became possible to balance surface properties and opacity with a small amount of coating. Calcium carbonate and kaolin are preferably contained in a ratio of 60:40 to 90:10. Increasing the kaolin ratio from 40 is not preferable because the coefficient of friction is excessively decreased and the opacity is decreased. However, it is not preferable because it cannot contribute to the reduction of the dynamic friction coefficient. As kaolin, those having an average particle diameter of 2 to 8 μm by the laser method are preferable because of high effect of improving opacity. The average particle size is determined by measuring the particle size distribution measuring apparatus (type: SALD-2000, Shimadzu) of the pigment slurry mixed with 0.2% by weight of dispersant (trade name: Aron T-50, manufactured by Toagosei Co., Ltd.). Means the median diameter obtained by measuring the particle size distribution at

The oil absorption of the filler in the base paper, the filler content, the coating amount of the surface treatment agent per side, and the calcium carbonate content in the pigment are within the specified values. Whiteness is 54% or more, opacity after printing is 90 or more, dynamic friction By using a coefficient of 0.45 to 0.65 and an oil absorption of 60 to 200 seconds, it is possible to obtain cold offset printing newsprint paper with good ink fillability and whiteness, high printing gloss, and less stickiness of printed matter. . The dynamic friction coefficient is preferably in the range of 0.45 to 0.65 for the reason described above. The oil absorption is preferably 60 to 200 seconds, and more preferably 75 to 110 seconds. If it is less than 60 seconds, roll contamination of the printing press tends to occur, and if it exceeds 200 seconds, set-off tends to occur. In general cold offset printing newsprints, the physical properties such as tightness and smoothness include the oil absorption of the filler in the base paper, the filler content and the coating amount of the surface treatment agent on one side, and the calcium carbonate in the pigment. By making the blending amount within the specified value, it becomes easy to control the oil absorption within a predetermined range, and it becomes possible to achieve both good post-printing opacity, printing workability and printing surface quality.

In the present invention, an adhesive is blended with the surface treatment agent together with the pigment in order to avoid troubles related to surface strength typified by piling. As an adhesive for increasing both surface strength and opacity, starches and synthetic latexes are preferable. These adhesives are particularly preferably used because they have good compatibility with pigments and hardly cause aggregation during coating. Starch has a high adhesion ability with fibers that are hydrophilic components, and it is easy to drop off from the paper surface when the coating amount is so small that the solid coating amount is 1.4 g / m ² or less per side. Fiber and the like are also preferable because they are strongly bonded. Examples of the starches include enzyme-modified starch, oxidized starch, etherified starch, esterified starch, cationized starch, and hydrophobic starch. Commonly used adhesives for coated paper such as water-soluble cellulose compounds such as carboxymethylcellulose, methylcellulose, and hydroxyalkylcellulose, polyvinyl alcohol compounds, polyacrylamides, proteins such as casein, soy protein, and synthetic proteins are used. You may use together more than a kind.

In the present invention, it is more preferable to use latex together with starch as an adhesive. Although there is no restriction | limiting in particular as Tg of latex, The thing of -50-20 degreeC is preferable in consideration of the balance of surface strength and Nepari. Those in this Tg range exhibit tackiness at room temperature and have good adhesion to pigments / fillers, but the polarity of the molecule is very low, and adhesion to strong hydrophilic cellulose fibers is difficult. It is used in combination with starch with high adhesive strength, and has the function of covering adhesion to weak pigments / fillers only with starch. In the case of a low coating amount as in the present invention, the effect of mutual action of the latex and starch is greatly affected. The latex is preferably a core-shell type. Low Tg latex has a high film-forming property and is rubbery even at room temperature, so that it is easy to develop tackiness and has a high ability to adhere between pigments. However, it is easy to stick on a blanket, and it tends to cause nepari. On the other hand, the high Tg latex has a low adhesive strength, but it is difficult to get a nepari. The core-shell type latex for paper coating generally has a high Tg shell and a low Tg core. In this structure, the adhesive strength of the pigment can be improved due to good film-forming properties and tackiness derived from the Tg of the core, while suppressing Nepari, which is greatly influenced by the surface layer of latex particles. The Tg of the shell is preferably 0 to 20 ° C, and the Tg of the core is preferably -50 to 0 ° C. If the Tg of the shell is less than 0 ° C., the tackiness is too strong, so that nepari is likely to occur, and if it exceeds 20 ° C., the adhesive strength of the pigment is lowered. If the core Tg is less than −50 ° C., the amount of styrene, which is a strong water repellent component, decreases, so that the water absorption is deteriorated, and if it exceeds 0 ° C., the pigment adhesion ability is insufficient and the strength development is deteriorated. Note that the same effect can be obtained with a latex called a concentration gradient type in which the composition from the inside of the particle to the outside changes continuously, but the core-shell type is more preferable because the influence of Tg control appears more clearly. .

In the present invention, in order to provide good coating suitability and good printing workability in the paper manufacturing process, the binder ratio of the binder to 100 parts of pigment is 40 to 150 parts by weight in terms of dry mass, More preferably, it mix | blends so that it may become 40 to 70 weight part. If it is less than 40 parts by weight, sufficient adhesion to the pigment and base paper surface fibers cannot be obtained. When the amount exceeds 150 parts by weight, the surface strength is increased, but the opacity and whiteness after printing are decreased, and a set-off trouble is likely to occur. Adhesive amount is particularly in the range of 40 parts by weight or more and less than 70 parts by weight, so that sufficient surface strength can be obtained, and the decrease in opacity and whiteness after printing due to the adhesive can be suppressed. It is also economically preferable.

The ratio of latex to 100 parts of starch is preferably 10 to 100 parts by weight, more preferably 10 to 70 parts. If the latex ratio is less than 10 parts by weight, the adhesion to pigments and fillers is insufficient, and troubles such as piling are likely to occur on the printing press. When the amount exceeds 100 parts by weight, the vehicle component in the ink is rapidly absorbed, the ink tack rises, adheres to and accumulates on the roll of the printing press, and there is a possibility of causing a smearing trouble due to this. In addition, there is a concern that the printing surface may be blurred due to deterioration of dry pick. Although the contact angle of water on the paper surface can be improved by blending the latex, the contact angle 0.1 seconds after the dropwise addition of water is desirably 80 ° or more. When the contact angle 0.1 seconds after water dripping is 80 ° or more, sufficient affinity for the ink is ensured and the ink deposition property is good. In addition, the wet surface strength required in cold offset newspaper printing can be easily obtained.

The apparatus for applying the coating composition to the base paper of the offset printing paper is not particularly limited. For example, an ink line or a party-to-roll size press, a blade metalling size press, a rod metalling size press, a gate Roll coaters such as roll coaters, trailing, flexible, roll applications, fountain applications, bevel type and vent type blade coaters such as short dwells, rod blade coaters, bar coaters, air knife coaters, curtain coaters, spray coaters, gravure coaters A publicly known apparatus such as the above 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, and infrared heater drying, are employable, for example.

In the production of the news offset printing paper for cold offset according to the present invention, after forming the coating layer of the coating composition, it is smoothed by 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 are appropriately used. As the calender finishing conditions, the temperature of the rigid roll, the calender pressure, the number of nips, the roll speed, the moisture before the calender, etc. are appropriately selected according to the required quality. Furthermore, the calendar device has 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 that is mirror-finished with a metal or hard chrome plating on the surface of the rigid roll. As the elastic roll, a roll formed by molding a resin roll such as urethane resin, epoxy resin, polyamide resin, phenol resin, polyacrylate resin, cotton, nylon, aramid resin or the like is used as appropriate. In addition, it is also possible to use a suitable combination of a water coating device, an electrostatic humidifier, a steam humidifier, and the like for humidity control and humidification of the coated paper after finishing with a calendar.

The base paper of the cold offset newspaper printing paper according to the present invention is obtained as follows. First, as a raw material pulp, one or more kinds of chemical pulp (NBKP, LBKP, etc.), mechanical pulp (GP, CGP, RGP, PGW, TMP, etc.), waste paper pulp (DIP, etc.) are appropriately mixed to prepare a stock. Is done. From the viewpoint of effective use of resources, it is preferable to mix 50% of waste paper pulp. Next, a filler having an oil absorption of 360 to 500 mL / 100 g is added to the stock so that the content in the product is 0.5 to 5.0% by weight, and if necessary, white carbon, clay, amorphous silica In addition, fillers such as talc, titanium oxide, or calcium carbonate are appropriately added, and if necessary, internal strength agents such as paper strength enhancers, yield improvers, reinforced rosin sizing agents, emulsion sizing agents, and water resistance agents. In general, publicly known and commonly used paper making chemicals such as ultraviolet ray inhibitors are added, and paper is made by a conventionally used paper machine to produce a base paper. 50 g / ^{m 2} or less as a product basis weight, and more preferably when the 35~45g / ^{m 2,} the effect of the present invention as desired is very remarkably exhibited particularly desirable. The printing paper thus obtained is subjected to a surface smoothing process by calendar feeding. In that case, machine calender finishing by a double-sided metal roll and soft calender finishing by passing paper through a pressure nip composed of a metal roll and an elastic roll are appropriately performed.

Also, use a size press, bill blade, gate roll coater, or pre-metering size press to pre-coat one or more layers of base paper pre-coated with starch, polyvinyl alcohol, etc., or a coating solution containing pigment and adhesive. The coated coated paper can also be used. The physical properties of this base paper need to be sufficient to allow penetrating and drying ink to be printed on a cold set type high-speed rotary press, and have physical strength such as tensile strength, tear strength, and elongation equivalent to that of general newsprint. I just need it.

The newspaper printing paper for cold offset of the present invention has a whiteness of 54% or more, more preferably 55% or more. The higher the whiteness, the better the color printing, because the printed color contrast can be obtained. Further, the opacity after printing is set to 90% or more. The higher, the better. A low opacity after printing is not preferable in the case of newsprint that prints on both sides because the printing quality on the back side is lowered. The cold set offset printing paper of the present invention is excellent in printability, and in particular, when printing in multi-color, there is no thickening of halftone dots and little back-through, so a high-quality image can be obtained.

The present invention will be specifically described below with reference to examples. Of course, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example show a mass part and mass%, respectively.
The following physical properties were measured for the cold offset newsprint papers as Examples and Comparative Examples obtained as described below, and the results are shown in Table 1.

The characteristic values of the filler and pigment used in the present invention are as follows. In the case of a particle slurry, after washing with filtered water, in the case of a powder, it is dried as it is at 105 ° C. with a dryer. Obtained by measurement.
(Pore capacity, pore diameter)
Measurement was performed using a mercury porosimeter (type: Pore Sizer 9320, manufactured by Micromeritics). Incidentally, the pore diameter 10 ⁵ Å or less of the pore surface area, for the pore volume, pore diameter was measured for the pores of 12Å~10 ⁵ Å.
(Average particle size)
In a laser diffraction particle size distribution analyzer (type: SALD-2000, manufactured by Shimadzu Corporation), the median diameter was defined as the average particle diameter.
(Oil absorption)
According to the method of JIS K5101, boiled linseed oil specified in JIS K5421 is dropped from a burette onto 5 g of the sample, and the amount of boiled linseed oil used until the whole becomes a putty-like mass is converted to the amount per 100 g of sample.

(Oil absorption)
5 μL of light oil whose kinematic viscosity coefficient was adjusted to 3 cSt was dropped onto the surface of the news offset printing paper for cold offset obtained in Examples and Comparative Examples using a microsyringe, and the time until the surface gloss was not visible was measured.
(Whiteness)
The whiteness in the present invention was measured by a method described in ISO 3688 using a spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd.) (measured with a spectral whiteness colorimeter of Suga Test Instruments).
(Dynamic friction coefficient)
Conforms to JIS P 8147.
Measurement at front and back-vertical and vertical, with a tensile speed of 200 mm / min.
(Contact angle)
About the newsprint for offset printing obtained in each Example and Comparative Example, using a dynamic surface contact angle measuring device (Dynamic Absorption Tester DAT1100, manufactured by Fibro) at 23 ° C. and 50% RH atmosphere, The surface contact angle 0.1 seconds after dropping was measured.

(Opacity after printing)
It conformed to JAPAN TAPPI No.45.

(Dry pick)
A sample strip having a width of 2 cm and a length of 20 cm was cut from the newsprint for offset printing obtained in each of the examples and comparative examples, and this was attached to a sample mount (OK special art post 256 g / m ² ). Printing was carried out using 0.4 cc of printing ink (manufactured by Industrial Machinery) (paper test SD50 Crimson B T & K TOKA Co., Ltd.), and the degree of picking on the printed surface was visually evaluated. Evaluation was carried out by a five-step evaluation.
<Evaluation criteria>
5: No fiber is removed and no white spots occur.
4: A slight amount of fiber was removed, and white spots were slightly observed (about 1 to 5 locations / 36 cm ² ).
3: A level where there is no problem in practical use although fibers are partially removed. The white areas are about 6 to 20 places / 36 cm ² .
2: Fibers are observed on the entire surface, and the area ratio of white spots is less than 5%.
1: Fibers are removed from the entire surface and the paper surface is peeled off, and the area ratio of white areas is 5% or more.
Those with an evaluation of less than 3 have practical problems.

(Wet pick)
In the same manner as the dry pick test described above, a sample mount on which the newspaper for offset printing obtained in each of the examples and comparative examples was pasted was prepared, and a rubber roll wetted with gauze moistened with an RI printing tester. After water was applied to the newspaper paper surface, printing was immediately performed using 0.5 cc of printing ink (manufactured by T & K TOKA Corporation), and the degree of picking on the printed surface was visually evaluated. Evaluation was performed by the following five-step evaluation.
<Evaluation criteria>
5: No fiber is removed and no white spots occur.
4: The fibers are taken out very slightly, and the white spots are slightly seen (about 1 to 5 places).
3: A level where there is no problem in practical use although fibers are partially removed.
2: Fibers are observed on the entire surface, and the area ratio of white spots is less than 5%.
1: Fibers are observed on the entire surface, and the area ratio of white areas is 5% or more.
Those with an evaluation of less than 3 have practical problems.

(Ink set)
The cold offset newsprint paper obtained in each of the examples and comparative examples was cut into strips, and a sample paper (OK special art post 256 g / m ² ) was attached side by side. Newspaper printing ink (NEWS WEBMASTER / process ink G2: Sakata Inx Co., Ltd.) for offset rotary presses with the corresponding metal rolls using an RI printing tester (made by Ishikawajima Industrial Machinery Co., Ltd.) with a rubber roll for ink kneading on the 4th cylinder Manufactured) 0.5 cc kneaded, moved the ink kneading rubber roll to the second cylinder, and newly installed a rubber roll wrapped with relatively smooth one-side coated paper for ink transfer on the fourth cylinder, Printing is performed on the second cylinder. When the 4th roll was touched, the rotation was temporarily stopped, and from there, the ink was transferred to the 4th roll by 2 cm at regular intervals, and the transfer density change was visually evaluated. Evaluation was performed in five stages. In the following, the reference product is the offset printing paper obtained in Comparative Example 2.
<Evaluation criteria>
5: Compared with the standard product, the ink density of the single-sided coated paper that transferred the surface of the newspaper printing paper for cold offset after printing is clearly lower. 4: The cold offset after printing is finished compared with the standard product The ink density of single-sided coated paper with the surface of newspaper printing paper used for printing is slightly low 3: Ink density equivalent to the standard product.
2: Compared with the standard product, the ink density of the single-sided coated paper that transfers the surface of the newspaper printing paper for printing after printing is slightly higher. 1: For cold offset after printing compared with the standard product The ink density of single-side coated paper to which the surface of newspaper printing paper has been transferred is clearly high.

(Cosmetic dirt)
The newspaper printing paper for cold offset obtained in each of the examples and comparative examples was printed at a speed of 120,000 copies / hour on a tower type multi-color newspaper printing press, and the degree of soiling on the paper surface due to the cosmetic was visually evaluated. Ranking was performed in five stages. In the following, the reference product is the offset printing paper obtained in Comparative Example 1.
<Evaluation criteria>
5: The level of scumming stain on the printed material is remarkably superior to that of the standard product. 4: The level of scumming stain on the printed material is slightly better than that on the standard product. degree.
2: Compared with the standard product, the degree of the cosmetic stain on the printed material is slightly inferior 1: Compared with the standard product, the degree of the cosmetic stain on the printed material is remarkably inferior. There are practical problems.

(Neppali)
For the newsprint for offset printing obtained in each example and comparative example, an offset printing machine (Mitsubishi Lithopia L-BT3-1100) in which an aluminum plate having only a non-image area and a blanket (DAY blanket 8891 manufactured by DAY International) was set was used. Using this, water printing was performed on all the cylinders 1 to 4 without applying ink, and after 200 copies were printed, the water supply was stopped, and the degree of sticking of newsprint paper to the blanket was visually determined. Evaluation was performed by the following five-step evaluation.
<Evaluation criteria>
5: No fiber removal occurs.
4: A very small amount of fiber was removed.
3: A level where there is no problem in practical use although fibers are removed.
2: Paper layer breakage occurred in part.
1: Paper layer breakage occurred on the entire surface.
Those with an evaluation of less than 3 have practical problems.

Manufacture of newsprint base paper (A) for cold offset printing Mixing at a ratio of 10 parts softwood bleached kraft pulp (NBKP), 26 parts thermomechanical pulp (TMP), 64 parts deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) Hydrated silicic acid with 390 mL / 100 g of oil absorption (own product) as filler, all of which are added at a ratio of mass% of dry pulp, and the paper stock obtained after adjusting the papermaking pH to 6.5 with sulfuric acid band the paper making by gap former paper machine, in basis weight 41.2 g / ^{m 2,} cold offset printing newsprint oil absorption contains 3.0% hydrated silicate of 390 mL / 100 g To obtain a paper.

Manufacture of newsprint base paper (B) for cold offset printing Mixing and disaggregating 10 parts of softwood bleached kraft pulp (NBKP), 26 parts of thermomechanical pulp (TMP), 64 parts of deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) Hydrated silicic acid (self-produced) with an oil absorption of 450 mL / 100 g as a filler, all of which are added at a ratio of mass% of dry pulp, and the paper material obtained after adjusting the papermaking pH to 6.5 with a sulfuric acid band the paper making by gap former paper machine, in basis weight 41.2 g / ^{m 2,} cold offset printing newsprint oil absorption contains 3.0% hydrated silicate of 450 mL / 100 g To obtain a paper.

Manufacture of newsprint base paper (C) for cold offset printing Mixing at a ratio of 10 parts softwood bleached kraft pulp (NBKP), 26 parts thermomechanical pulp (TMP), 64 parts deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) After adding 7.5% of hydrated silicic acid (own product) with an oil absorption of 390 mL / 100 g as a filler, all of these were added at a ratio of mass% of dry pulp, and after adjusting the papermaking pH to 6.5 with a sulfuric acid band, papermaking obtained stock with gap former paper machine, in basis weight 41.2 g / ^{m 2,} cold offset printing oil absorption contains 4.5% hydrated silicate of 390 mL / 100 g To obtain a newsprint paper.

Manufacture of newsprint base paper (D) for cold offset printing Mixing and disaggregation at a ratio of 10 parts softwood bleached kraft pulp (NBKP), 26 parts thermomechanical pulp (TMP), 64 parts deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) Hydrated silicic acid with 390 mL / 100 g of oil absorption (own product) as filler, all of which are added at a ratio of mass% of dry pulp, and the paper stock obtained after adjusting the papermaking pH to 6.5 with sulfuric acid band the paper making by gap former paper machine, in basis weight 41.2 g / ^{m 2,} cold offset printing newsprint oil absorption contains 0.8% hydrated silicate of 390 mL / 100 g To obtain a paper.

Manufacture of newsprint base paper (E) for cold offset printing Mixing at a ratio of 10 parts softwood bleached kraft pulp (NBKP), 26 parts thermomechanical pulp (TMP), 64 parts deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) Hydrated silicic acid with 390 mL / 100 g of oil absorption (own product) as filler, all of which are added at a ratio of mass% of dry pulp, and the paper stock obtained after adjusting the papermaking pH to 6.5 with sulfuric acid band the paper making by gap former paper machine, in basis weight 41.2 g / ^{m 2,} cold offset printing newsprint oil absorption contains 1.2% hydrated silicate of 390 mL / 100 g To obtain a paper.

Manufacture of newsprint base paper (F) for cold offset printing Mixing with a ratio of 10 parts softwood bleached kraft pulp (NBKP), 26 parts thermomechanical pulp (TMP), 64 parts deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) Hydrated silicic acid (trade name: Tocsil GU-N, manufactured by Tokuyama Co., Ltd.) having an oil absorption of 200 mL / 100 g as a filler, all of which are added in a proportion of mass% of dry pulp, and the papermaking pH is 6. After adjustment to 5, the paper stock obtained was made with a gap former paper machine and contained 3.0% of hydrated silicic acid having a weight of 42.3 g / m ² and an oil absorption of 200 mL / 100 g. A newsprint base paper for cold offset printing was obtained.

Manufacture of newsprint base paper (G) for cold offset printing Mixing at a ratio of 10 parts softwood bleached kraft pulp (NBKP), 26 parts thermomechanical pulp (TMP), 64 parts deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) Hydrated silicic acid (trade name: Tocsil GU-N, manufactured by Tokuyama Co., Ltd.) having an oil absorption of 200 mL / 100 g as a filler, all of which are added in a proportion of mass% of dry pulp, and the papermaking pH is 6. After adjusting to 5, the resulting stock was made with a gap former paper machine and contained 3.0% of hydrated silicic acid with a rice floor of 41.2 g / m ² and an oil absorption of 200 mL / 100 g. A newsprint base paper for cold offset printing was obtained.

Manufacture of newsprint base paper (H) for cold offset printing Mixing at a ratio of 10 parts softwood bleached kraft pulp (NBKP), 26 parts thermomechanical pulp (TMP), 64 parts deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) After adding 3.0% of hydrated silicic acid (own product) with an oil absorption of 390 mL / 100 g as a filler, all of them were added at a ratio of mass% of dry pulp, and after adjusting the papermaking pH to 6.5 with a sulfuric acid band, the resulting stock was paper in the gap former paper machine, in basis weight 41.2 g / ^{m 2,} cold offset printing oil absorption contains 6.0% hydrated silicate of 390 mL / 100 g To obtain a newsprint paper.

Manufacture of newsprint base paper (J) for cold offset printing Mixing and disaggregating 10 parts of softwood bleached kraft pulp (NBKP), 26 parts of thermomechanical pulp (TMP), 64 parts of deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) Light calcium carbonate with 80mL / 100g oil absorption (own product) as a filler, all of which are added at a ratio of mass% of dry pulp, and the paper stock obtained after adjusting the papermaking pH to 6.5 with sulfuric acid band the paper making by gap former paper machine, in basis weight 41.2 g / ^{m 2,} cold Offset oil absorption contains 6.0% precipitated calcium carbonate 80 mL / 100 g It was obtained for printing newsprint paper.

Manufacture of newsprint base paper (K) for cold offset printing Mixing at a ratio of 10 parts softwood bleached kraft pulp (NBKP), 26 parts thermomechanical pulp (TMP), 64 parts deinked pulp (DIP) In the pulp slurry beaten with a refiner, 0.5% cationized starch (P3Y, manufactured by PIRAAB STARC Co. Ltd), 0.8% neutral rosin sizing agent (N815, manufactured by Arakawa Chemical Co., Ltd.) Hydrated silicic acid with 390 mL / 100 g of oil absorption (own product) as filler, all of which are added at a ratio of mass% of dry pulp, and the paper stock obtained after adjusting the papermaking pH to 6.5 with sulfuric acid band the paper making by gap former paper machine, in basis weight 37.2 g / ^{m 2,} cold offset printing newsprint oil absorption contains 3.0% hydrated silicate of 390 mL / 100 g To obtain a paper.

Example 1
For 70 parts of light calcium carbonate (Brilliant S15, manufactured by Shiraishi Kogyo Co., Ltd.) and 30 parts of kaolin (trade name: Milagros J, manufactured by Seal Co., Ltd., average particle size 4.6 μm), a dispersant (trade name: Aron T- 50, manufactured by Toa Gosei Co., Ltd.) 0.1 part was added and dispersed in 60% dispersion slurry, 8.5 parts of styrene-butadiene latex (trade name: T-2635R, manufactured by JSR Corporation) was gelatinized and dissolved. Oxidized corn starch (trade name: Oji Ace A, manufactured by Oji Cornstarch Co., Ltd.) 55 parts, lubricant (trade name: SN8004SP, manufactured by San Nopco Co., Ltd.) 0.23 parts, water resistant agent (trade name: Sumires SPI-102A, Sumitomo Chemical Co., Ltd.) 0.15 part, fluorescent dye (trade name: Kaya Hall BHT, Nippon Kayaku Co., Ltd.) 0.5 part solid concentration 25% Paint was adjusted, which on both sides of the base paper (A), applied as a coating amount after drying using a gate roll coater is per side 0.8 g / m ^2, and dried to real amounts 42 A newsprint for cold offset printing of .8 g / m ² was obtained.

Example 2
Cold offset printing newsprint with an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that the base paper of Example 1 was changed to base paper (B).

Example 3
Cold offset printing newsprint with an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that the base paper of Example 1 was changed to base paper (C).

Example 4
Cold offset printing newsprint with an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that the base paper of Example 1 was changed to base paper (D).

Example 5
Cold offset printing newsprint paper having an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that 85 parts of light calcium carbonate and 15 parts of kaolin were used as the pigment of Example 1.

Example 6
Cold offset printing newsprint with an actual amount of 42.8 g / m ² , except that the base paper of Example 1 is base paper (E), 60 parts of light calcium carbonate and 40 parts of kaolin are used. Got.

Example 7
Example 1 is the same as Example 1 except that the light calcium carbonate (Brilliant S15, manufactured by Shiraishi Kogyo Co., Ltd.) is changed to light calcium carbonate (own product, average particle size 0.8 μm, oil absorption 45 mL / 100 g). Similarly, newsprint paper for cold offset printing having an actual amount of 42.8 g / m ² was obtained.

Example 8
The pigment of Example 1 was changed to 80 parts of light calcium carbonate, and replaced with 20 parts of kaolin (trade name: Milagros J, manufactured by Seal Co., Ltd., average particle size: 1.1 μm), kaolin (trade name: Contour 1500, Imerys). Cold offset printing newsprint paper with an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that the amount was 20 parts (manufactured by Co., Ltd., average particle diameter 4.6 μm).

Example 9
21 parts of styrene-butadiene latex (trade name: T-2635R, manufactured by JSR Corporation) of Example 1 and 43 parts of gelatinized and dissolved oxidized corn starch (trade name: Oji Ace A, manufactured by Oji Corn Starch Co., Ltd.) Except for the above, a news paper for cold offset printing having an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1.

Comparative Example 8
The same procedure as in Example 1 was conducted except that 65 parts of gelatinized and dissolved oxidized corn starch (trade name: Oji Ace A, manufactured by Oji Constarch Co., Ltd.) of Example 1 was used and styrene-butadiene latex was not used. A news paper for cold offset printing having an amount of 42.8 g / m ² was obtained.

Comparative Example 9
19 parts of styrene-butadiene latex (trade name: T-2635R, manufactured by JSR Corporation) and 19 parts of gelatinized and dissolved corn starch (trade name: Oji Ace A, manufactured by Oji Constarch Corporation) of Example 1 A news paper for cold offset printing having an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that.

Comparative Example 1
Gelatin-dissolved oxidized corn starch (trade name: Oji Ace A, manufactured by Oji Constarch Co., Ltd.) 100 parts of a 7% solid content paint is prepared, and this is applied to both sides of the base paper (F) on a gate roll coater. Was used so that the coating amount after drying was 0.25 g / m ² per side and dried to obtain a news paper for cold offset printing having an actual amount of 42.8 g / m ² .

Comparative Example 2
Cold offset printing newsprint with an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that the base paper of Example 1 was changed to base paper (G) .

Comparative Example 3
Cold offset printing newsprint with an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that the base paper of Example 1 was changed to base paper (H) .

Comparative Example 4
Cold offset printing newsprint with an actual amount of 42.8 g / m ² was obtained in the same manner as in Example 1 except that the base paper of Example 1 was changed to base paper (J) .

Comparative Example 5
For 70 parts of light calcium carbonate (trade name: Brilliant S15, manufactured by Shiraishi Kogyo Co., Ltd.) and 30 parts of kaolin (trade name: Milagros J, manufactured by Seal Co., Ltd., average particle size 4.6 μm), a dispersant (trade name: Aron T-50 (manufactured by Toa Gosei Co., Ltd.) 0.1 part was added and dispersed into a 60% dispersed slurry, 8.5 parts of styrene-butadiene latex (trade name: T-2635R, manufactured by JSR Corporation), glue Oxidized corn starch (trade name: Oji Ace A, manufactured by Oji Constarch Co., Ltd.) 55 parts, lubricating oil (trade name: SN8004SP, manufactured by San Nopco Co., Ltd.) 0.23 parts, water resistant agent (trade name: Sumires SPI) -102A, manufactured by Sumitomo Chemical Co., Ltd.) 0.15 parts, fluorescent dye (trade name: Kaya Hall BHT, manufactured by Nippon Kayaku Co., Ltd.) 0.5 parts solids concentration 45 The paint was adjusted, applying this so that the coating amount per side 2.8 g / m ² after drying using a gate roll coater on both surfaces of the base paper (K), dried real amount 42 A newsprint for cold offset printing of .8 g / m ² was obtained.

Comparative Example 6
Cold offset newspaper in the same manner as in Example 1 except that 100 parts of kaolin of Example 1 (trade name: Milagros J, manufactured by Seal Co., Ltd., average particle size 4.6 μm) was used, and light calcium carbonate was not used. I got printing paper.

Comparative Example 7
Example except that 30 parts of light calcium carbonate (Brilliant S15, manufactured by Shiraishi Kogyo Co., Ltd.) and 70 parts of kaolin (trade name: Milagros J, manufactured by Seal Co., Ltd., average particle size 4.6 μm) of Example 1 were used. In the same manner as in 1, a newspaper paper for cold offset was obtained.

Claims (5)

A cold offset printing paper obtained by applying a surface treatment agent mainly composed of a pigment and an adhesive onto a base paper and drying the base paper, and containing 0.5 to 5.0% by weight of an oil absorption amount of 360 to 500 ml / 100 g. Furthermore, as a pigment, calcium carbonate and kaolin are contained in a ratio of 60:40 to 90:10, and as an adhesive, starch and latex are contained in 10 to 100 parts by weight of latex with respect to 100 parts by weight of starch, A surface treatment agent having an adhesive amount of 40 parts by weight or more and less than 70 parts by weight per 100 parts by weight of pigment is provided as a surface treatment agent layer with a coating amount of 1.4 g / m ² or less per side, and a dynamic friction coefficient is 0.45 to 0.65, whiteness 54% or more, after printing opacity 90% or more, and 200 seconds from the oil absorption 60 seconds, 0.1 seconds after the contact angle under water droplets between the paper surface and the water Value of 80 ° or more, basis weight 0 g / ^{m 2} or less of cold offset printing newsprint. The pore volume cumulative volume in the range of 0.01 to 10.0 μm is 2.0 to 5.0 mL / g, and the central pore diameter of the pore volume 50% is in the range of 0.05 to 0.20 μm. The integrated volume in a pore diameter range of 0.01 to 0.1 μm is 1.0 mL / g or more, and the average particle diameter by a laser method is 15 to 40 μm or less. Newspaper for cold offset printing. The news paper for cold offset printing according to claim 1 or 2, wherein the average particle diameter of the kaolin laser in the previous period is 2 to 8 µm. The newsprint for cold offset printing according to any one of claims 1 to 3 , wherein the calcium carbonate is cubic light calcium carbonate. The newsprint for cold offset printing according to any one of claims 1 to 4, wherein the latex is a core-shell type latex.