JP5354487B2 - Newsprint paper for offset printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain newsprint paper for offset printing which is suppressed in the occurrence of pilings and stickiness troubles. <P>SOLUTION: The newsprint paper for offset printing is such that both sides of base paper incorporated with 0.1-0.4 mass% of a neutral rosin sizing agent are coated with surface treatment agent consisting mainly of a low-viscosity starch with a 7%-Brookfield viscosity of 7 mPa s or lower at 50&deg;C and an olefinic surface sizing agent followed by drying so as to be 50 mN/30 mm or lower in stickiness strength and 30-200 s in water absorption time. Furthermore, in the newsprint paper, it is preferable that the coating level of the low-viscosity starch is 0.2-1.0 g/m<SP>2</SP>per side, and the mass ratio of the low-viscosity starch in the surface treatment agent to the olefinic surface sizing agent is (99:1) to (70:30). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a newsprint for offset printing that does not cause piling and nippar trouble during printing.

  In recent years, newspapers for offset printing are often used for color printing, and the higher the whiteness of the base paper, the better the appearance of color printing. Yes. In addition, the newspaper for offset printing is required to be lightweight (low basis weight). Paper with a low basis weight tends to show through on the front surface when viewed from the back side, and through printing tends to occur on color printing to which a relatively large amount of ink is applied. Therefore, high opacity is required even with a low basis weight.

As a method for improving the whiteness of newsprint, a method of internally adding a filler is employed. Adding a filler can increase whiteness and opacity.
As fillers usually used for newsprint, white carbon, talc, clay, titanium dioxide, calcium carbonate, urea formalin resin, and the like are used. For example, since titanium dioxide has a very high light scattering coefficient, it is effective for improving the opacity, but it is expensive and is not widely used in newsprint. Talc and kaolin are inexpensive, but their oil absorption is not so high. White carbon, which has high oil absorbency, is highly used because of its high effect of improving opacity after printing with a relatively small addition amount. In addition, calcium carbonate is decomposed by acidic papermaking, so its use is limited to neutral papermaking, but it is relatively inexpensive and has high whiteness, as well as having various particle shapes and oil absorption characteristics. Because it can be used, it is often used in neutral papermaking.

  However, when these fillers are added in an increased amount, the yield of the paper machine wire is deteriorated, and there is a problem that the filler tends to fall off from the paper at the time of printing and is taken up by the blanket. In order to prevent piling, the coating amount of a water-soluble adhesive such as starch or polyacrylamide applied on the surface is increased. Nepari is a phenomenon in which the dampening water adhering to the base paper in offset printing causes adhesives to increase the tackiness of the paper surface. If a Nepari trouble occurs, the paper sticks to the blanket or the paper breaks. Sometimes. In other words, piling can be reduced by increasing the amount of adhesive applied, but increasing the amount of adhesive applied has the contradictory property of causing Nepari trouble, making it difficult to improve both simultaneously. ing.

Specifically, the following techniques have been proposed as a method for solving the Neppari trouble.
(1) Newsprint paper for offset printing in which the product of the viscosity and the coating amount of a surface treatment agent containing a specific processed starch is in a specific range. (Patent Document 1)
(2) Newsprint paper for offset printing, which contains an olefin-based sizing agent in a pigment coating layer having a dry coating amount of 0.3 to 3 g / m ² . (Patent Document 2)
(3) Newsprint paper for offset printing provided with a pigment coating layer containing a sizing agent in which the calcium carbonate contained in the base paper is 2% or more and less than 5% and the coating amount is 3 g / m ² or less. (Patent Document 3)
In addition, the following technique has been proposed as a technique for obtaining a neutral paper excellent in size by specifying an internal sizing agent and a surface sizing agent.
(4) In non-coated printing paper containing calcium carbonate as a filler and further containing a neutral rosin sizing agent as an internal sizing agent, an aqueous polyacrylamide resin solution having a molecular weight of at least 350,000 and styrene as a surface sizing agent A non-coated printing paper characterized by using a size press solution containing acrylic acid co-polymer and having a Steecht sizing degree in the range of 15 to 40 seconds. (Patent Document 4)
(5) Neutral paper containing a quaternary amine starch derivative having a substitution degree of 0.02 to 0.05 as a starch derivative and using an alkyl ketene dimer or alkenyl succinic anhydride as an internal sizing agent, A method for producing neutral paper, which comprises coating an aqueous solution of an anionic styrene-acrylonitrile copolymer. (Patent Document 5)
Further, the sizing degree of the base paper and the product is defined, and the following technique has been proposed as a technique for imparting sizing by applying a specific surface sizing agent.
(6) Newspaper printing paper provided with a gate roll coating layer comprising a water absorption resistance control composition containing a specific component on a base paper containing 30% by weight or more of mechanical pulp and a drip water absorption of 10 seconds or less. The coating layer is applied at a speed of 1100 m / min to 1800 m / min, and the coating amount of the water absorption resistance control composition is in the range of 0.1 to 0.3 g / m ² (per one side). And a drip water absorbency of 60 seconds or more. (Patent Document 6)
JP 2006-118114 A JP 2006-169693 A JP 2007-162173 A Japanese Patent Laid-Open No. 08-120592 Japanese Patent No. 3205971 Japanese Patent No. 3266903

The invention described in Patent Document 1 specifies the composition, viscosity, and coating amount of the surface treatment agent, but does not specify the sizing agent contained in the base paper as in the present invention.
The invention described in Patent Document 2 uses an olefin-based sizing agent as a surface sizing agent in the pigment coating layer, but is not specified for the sizing agent contained in the base paper.
In the invention described in Patent Document 3, it is said that the pigment coating amount is preferably 0.5 g / m ² or more. Since the pigment coating amount is large, the coating amount of the adhesive is also large, and piling and It seems difficult to balance trouble prevention and ensure ink drying.
The invention described in Patent Document 4 specifies the sizing agent, the surface sizing agent, and the sizing degree of the product contained in the base paper, but it has not been studied for piling or nepari.
The invention described in Patent Document 5 is intended to obtain a neutral paper excellent in sizing properties immediately after papermaking by specifying the sizing method of the base paper and the components of the surface sizing agent. Not a thing.
Although the invention described in Patent Document 6 is improved in size by only a method of externally adding a specific chemical, it does not refer to the size of internal addition and does not discuss piling.
As described above, the conventional technology cannot provide newsprint paper for offset printing that suppresses the occurrence of piling and Nepari trouble.

In order to solve the above problems, the present invention has the following configuration.
(1) Low-viscosity starch having a B-type viscosity of 7 mPa · s or less at 50 ° C. and 7% on both surfaces of a base paper to which 0.1 to 0.4% by mass of a neutral rosin sizing agent is added, and an olefinic surface A sizing agent and a surface treatment agent containing a pigment as a main component are coated and dried, the coating amount of the pigment is 0.01 to 0.3 g / m 2 on one side, the Nepari strength is 50 mN / 30 mm or less, and water absorption Newsprint paper for offset printing, characterized in that the time (according to JAPAN TAPPI No. 32-2, the amount of dripping water is 5 μl) is 30 to 200 seconds.
(2) The coating amount of the low-viscosity starch is 0.2 to 1.0 g / m 2 on one side, and the mass ratio of the low-viscosity starch and the olefin-based surface sizing agent contained in the surface treatment agent is 99: 1 to 70:30. The newsprint paper for offset printing according to claim 1, wherein the newsprint paper is in the range of

  According to the present invention, it is possible to obtain a newsprint for offset printing that is free from occurrence of piling and trouble.

Embodiments of the present invention will be described below.
The newsprint for offset printing according to the present invention uses waste paper deinked pulp (DIP) as the main component of the raw material pulp. In DIP, waste newspapers and magazine waste papers are usually disaggregated in a disaggregation step, then dust is removed in a dust removal step, a deinking agent is added in the deinking step, and ink is floated and separated by a flowator. And after removing a foreign material in a selective process, bleaching is performed in a bleaching process.
Moreover, as pulp used in conjunction with DIP, mechanical pulp or chemical pulp is used. Examples of the mechanical pulp include stone ground pulp (SGP), pressurized stone ground pulp (PGP), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), and the like. Examples of the pulp include softwood kraft pulp (NKP), hardwood kraft pulp (LKP), and the like, which can be appropriately selected from these pulps. Mechanical pulp is preferably used in terms of opacity, and chemical pulp is preferably used in terms of strength.

The newsprint paper for offset printing of the present invention can be added with publicly known fillers and papermaking chemicals as required. As filler, white carbon, clay, silica, talc, titanium oxide, calcium carbonate, synthetic resin filler (vinyl chloride resin, polystyrene resin, urea formalin resin, melamine resin, styrene / butadiene copolymer resin, etc.) etc. Can be added. Especially in neutral papermaking, calcium carbonate is effective in terms of the effect of improving whiteness and opacity and cost. Papermaking chemicals include polyacrylamide polymers, polyvinyl alcohol polymers, cationized starch, amphoteric starch, urea / formalin resin, melamine / formalin resin and other paper strength enhancers, and acrylamide / aminomethylacrylamide. Yield improver such as copolymer salt, cationized starch, amphoteric starch, polyethyleneimine, polyethylene oxide, acrylamide / sodium acrylate copolymer, neutral paper sizing agent, aluminum sulfate (sulfate band), dye, You may contain adjuvants, such as a slime control agent, a pitch control agent, and an antifoamer.
The physical properties of the newsprint for offset printing need to be printable by an offset printing machine, and any physical properties such as tensile strength, tear strength, and elongation equivalent to those of ordinary newsprint for offset printing may be used. .

  Neutral papermaking sizing agents include reactive sizing agents that react directly with cellulose, cationic sizing agents that have self-fixing properties, and neutral rosin sizing agents. Reactive sizing agents include alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), and other various derivatives. However, the AKD sizing agent is relatively stable and effective even at a low addition amount, but there is a problem that the rise of the sizing effect is slow and the sizing degree is difficult to adjust because the sizing degree changes with time. In addition, ASA-based sizing agents have the disadvantages that an emulsification operation is required immediately before use, and that machine contamination is likely to occur at high addition amounts. In addition, the cationic sizing agent has a drawback that the effect at a low blending ratio is lower than that of the reactive sizing agent.

In the present invention, a neutral rosin sizing agent is used as an internal sizing agent. Neutral rosin sizing agent is a modified rosin sizing agent that has been used in the acidic range of pH 4-5, and it is a rosin sizing agent that exhibits a high effect from weak acidity of pH 6-8 to neutrality. Yes, in the present invention, the addition amount is set in an appropriate range, and by using a low-viscosity starch and a surface treatment agent mainly composed of an olefin-based surface sizing agent, ensuring the sizing of paper, piling, It is possible to suppress the occurrence of Nepari trouble.
Here, the appropriate amount of neutral rosin sizing agent added to the base paper is 0.1 to 0.4% by mass. By controlling within this range, the surface treatment agent can be permeated to prevent piling and Nepari trouble. When the amount is less than 0.1% by mass, the surface treatment agent is excessively permeated, and the residual amount on the paper surface is reduced, so that a tendency to piling tends to occur and the sizing degree at the time of printing becomes insufficient. If it exceeds 0.4 mass%, the penetration of the surface treatment agent will be small, the residue on the surface of the paper will increase, and the tendency of the size will be too high and the expression of the size will be too high. Will also occur.

In the present invention, a surface treatment agent containing an adhesive and a surface sizing agent is applied and dried on both sides of the base paper.
As the adhesive used in the present invention, low-viscosity starch is used. The viscosity is 7 mPa · s or less as a B-type viscosity measured at a concentration of 7% and a temperature of 50 ° C. Examples of the low-viscosity starch include dry starch and the like, for example, dry low molecular weight hydroxyethylated starch. This dry-type low-viscosity hydroxyethylated starch is prepared by subjecting hydroxyethylated starch to a solid state with a water content of 5 to 17%, and acid-treating with hydrogen chloride gas, hydrochloric acid, sulfuric acid or the like, or ammonium persulfate, hydrogen peroxide, It has been reduced in molecular weight by oxidation treatment with chlorine gas or the like. Such a low-viscosity starch is less likely to cause Nepari trouble, and penetrates into the base paper during coating. As an adhesive, polyacrylamide, polyvinyl alcohol, latex or the like may be used in combination with the low viscosity starch.

  As surface sizing agents, alkyl ketene dimers, alkenyl succinic anhydrides, styrene acrylics, styrene acrylates and the like are generally known. In the present invention, olefin surface sizing agents are used. The olefin-based surface sizing agent has a less tendency to have Nepari than other surface sizing agents, and can prevent Nepari trouble.

  The olefin surface sizing agent used in the present invention is a copolymer containing an olefinic unsaturated monomer as a constituent monomer. Specifically, it is a copolymer comprising an olefinically unsaturated monomer which is a hydrophobic unsaturated monomer and a carboxy group-containing unsaturated monomer as constituent elements.

By combining the above configurations, the newsprint for offset printing of the present invention has a Nepari strength of 50 mN / 30 mm or less. Here, the Nepari intensity is a value measured as follows.
Cut two newspapers for offset printing 1 inch wide x 19 cm long, float the coated surfaces on a water surface at a temperature of 20 ° C for 5 seconds, and then immediately coat the coated surfaces (wet coated surface and wet coated surface) Adhere. Subsequently, the backing sheet is overlapped on both outer sides, passed twice through a roll at a nip pressure of 40 kgf / cm, and conditioned at 23 ° C. and 50% RH for 24 hours. The peel strength is measured with a tensile tester under conditions of a pulling speed of 100 mm / min. The larger the measured value, the harder it is to peel off (stronger adhesiveness).

  Furthermore, the newsprint for offset printing of the present invention has a water absorption time (conforming to JAPAN TAPPI No. 32-2, 5 μl of dripping water) of 30 to 200 seconds. By setting it within this range, it is possible to prevent nepari trouble and piling in a well-balanced manner. If the water absorption time is shorter than 30 seconds (the degree of sizing is low), Nepari trouble and piling are likely to occur, and if it is lower than 200 seconds (the degree of sizing is high), ink deposition may be deteriorated.

In the newsprint for offset printing of the present invention, the coating amount of starch is 0.2 to 1.0 g / m ² on one side, and the mass ratio of starch and surface sizing agent contained in the surface treatment agent is 99: 1 to 70. : 30. When the coating amount of starch is less than 0.2 g / m ² on one side, it tends to cause piling, and when it is more than 1.0 g / m ² , it tends to cause nappari trouble.
In addition, the mass ratio of the starch and the surface sizing agent contained in the surface treatment agent is 99: 1 to 70:30. It is easy to cause, and if there is a large amount of the surface sizing agent beyond this range, the fleshing deteriorates and causes uneven flaking.

In the present invention, it is also a preferred embodiment to use a pigment as the surface treatment agent. Examples of the pigment used include titanium dioxide, white carbon, calcium carbonate, calcined kaolin, and kaolin. However, titanium dioxide and white carbon are expensive, and calcium carbonate, calcined kaolin, and kaolin are used alone or in combination. Is preferred.
In general, it is considered that when a pigment is applied, it is more likely that pyring will occur than when it is not applied. However, as in the present invention, a very small amount of pigment is applied, and a low-viscosity starch is used. When combined with the use of olefin-based surface sizing agents, the pigment particles are exposed on the paper surface by coating the pigment, weakening the adhesion to the blanket, and suppressing papling, thereby suppressing piling. Can do. Further, as an effect of pigment coating, there is an increase in whiteness and opacity.

Here, it is preferable that the coating amount of the pigment is 0.01 to 0.3 g / m ^{2 on} one side. If the coating amount of the pigment is less than 0.01 g / m ² on one side, the effect of suppressing the above-described pigment nepari becomes low. If the coating amount of the pigment is more than 0.3 g / m ² on one side, there is a risk of causing a problem of the pile. If the coating amount of the adhesive is increased in order to prevent this, the Nepari trouble is likely to occur. It becomes difficult to balance.

  In the present invention, a gate roll coater is preferably used as a coating apparatus for coating the surface treatment agent. The gate roll coater is suitable for uniformly applying a low-concentration, low-viscosity surface treatment agent, and has few troubles such as streak and good continuous operability. The coating amount of the surface treatment agent in the gate roll coater is adjusted by the temperature, concentration, viscosity, surface ratio of the applicator roll and metering roll, and the like.

  In addition, chemicals generally used for surface treatment agents such as dispersants, pH adjusters, preservatives, and fluorescent dyes can be used as the surface treatment agent.

  In the production of newsprint for offset printing according to the present invention, the surface treatment agent is coated and dried, and then smoothed by a calendar device. As such a calendar device, commonly used calendar devices such as a chilled calendar, a super calendar, a soft calendar, and a gloss calendar can be used. As described above, the newsprint for offset printing of the present invention is obtained.

Hereinafter, the present invention will be described more specifically with reference to examples. Unless otherwise specified,% represents mass% of solid content, part represents mass part of solid content, and ppm represents mass standard.
Example 1
80 parts of newspaper waste ink deinked pulp and 20 parts of thermomechanical pulp are used as pulp raw materials, and sulfuric acid band (made in-house) is 2.0% of pulp raw materials, cationized starch (trade name CATO304, manufactured by NSC Corporation) Was added 0.3%, and a neutral rosin sizing agent (trade name CC1404 manufactured by Seiko PMC Co., Ltd.) was added 0.25% thereto. As a filler, 1.0% of white carbon (manufactured in-house) was added, and a yield improver (trade name Hymo Lock ND-260, manufactured by Hymo Co., Ltd.) was added at 200 ppm as an active ingredient to the pulp. Paper is made with a gap former type paper machine, the following surface treatment agent is coated on both sides of the base paper with a gate roll coater, soft calendered, and newsprint paper for offset printing with a basis weight of 43.0 g / m ² is manufactured. did.
Surface treatment agent Low viscosity starch (trade name GRS-T120 manufactured by Oji Cornstarch Co., Ltd., B-type viscosity 6.2 mPa · s at 50 ° C., 7%)
Olefin-based surface sizing agent (trade name Polymaron OM-25, manufactured by Arakawa Chemical Industries, Ltd.)
Solid mass ratio of starch and surface sizing agent 95: 5
Solid content 5% (before pigment mixing)
Coating amount 0.4g / m ² (single side, excluding pigment)
Pigment coating Kaolin (trade name Capim DG, manufactured by Imerizu Minerals Japan) 0.03 g / m ² (single side)

(Example 2)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the addition amount of the neutral rosin sizing agent was 0.12%.

(Example 3)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the amount of neutral rosin sizing agent added was 0.38%.

Example 4
The solid content concentration of the surface treatment agent is 6.5% (before pigment mixing), the coating amount is 0.5 g / m ² (one side, excluding the pigment), and the mass ratio of the surface treatment agent starch to the surface sizing agent is 94: 6. A newsprint for offset printing was manufactured in the same manner as in Example 1 except that.

(Example 5)
The solid content concentration of the surface treatment agent is 4.0% (before pigment mixing), the coating amount is 0.27 g / m ² (one side, excluding pigment), and the solid content mass ratio of the surface treatment agent starch to the surface sizing agent is 81. : Newsprint paper for offset printing was produced in the same manner as in Example 1 except that it was set to 19.

(Example 6)
The solid content concentration of the surface treatment agent is 9.0% (before pigment mixing), the coating amount is 0.95 g / m ² (one side, excluding pigment), and the mass ratio of the surface treatment agent starch to the surface sizing agent is 97: 3. A newsprint for offset printing was manufactured in the same manner as in Example 1 except that.

(Example 7)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the amount of pigment applied was 0.01 g / m ² (one side).

(Example 8)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the amount of pigment applied was 0.22 g / m ² (one side).

(Comparative Example 1)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the addition amount of the neutral rosin sizing agent was 0.08%.

(Comparative Example 2)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the addition amount of the neutral rosin sizing agent was 0.45%.

(Comparative Example 3)
For offset printing in the same manner as in Example 1, except that the internal sizing agent was changed and 0.35% of an acidic rosin sizing agent (trade name AL1206, manufactured by Seiko PMC Co., Ltd.) was added. Made newsprint.

(Comparative Example 4)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the internal sizing agent was not used and the pigment was not applied.

(Comparative Example 5)
The surface treatment agent starch was changed to oxidized starch (trade name Oji Ace A, manufactured by Oji Cornstarch Co., Ltd., B type viscosity 7.5 mPa · s at 50 ° C., 7%), except that no pigment was applied. In the same manner as in Example 1, newsprint for offset printing was manufactured.

(Comparative Example 6)
An offset printing newsprint was produced in the same manner as in Comparative Example 5 except that a styrene surface sizing agent (trade name: Polymaron NS-25, manufactured by Arakawa Chemical Industries, Ltd.) was used as the surface sizing agent.

(Comparative Example 7)
For offset printing as in Comparative Example 6, except that the starch of the surface treatment agent is a low-viscosity starch (trade name GRS-T120 manufactured by Oji Cornstarch Co., Ltd., B-type viscosity 6.2 mPa · s at 50 ° C., 7%) Made newsprint.

(Comparative Example 8)
The solid content concentration of the surface treatment agent is 4.0% (before pigment mixing), the coating amount is 0.28 g / m ² (one side, excluding pigment), and the solid content mass ratio of the surface treatment agent starch to the surface sizing agent is 64. : Newsprint paper for offset printing was manufactured in the same manner as in Example 1 except that no pigment was applied.

(Comparative Example 9)
Comparison is made except that the solid content concentration of the surface treatment agent is 3% (before pigment mixing), the coating amount is 0.17 g / m ² (one side, excluding pigment), and the solid content mass ratio of starch to the surface sizing agent is 88:12. Newsprint paper for offset printing was produced in the same manner as in Example 7.

(Comparative Example 10)
Comparison is made except that the solid content concentration of the surface treatment agent is 12% (before pigment mixing), the coating amount is 1.22 g / m ² (one side, excluding pigment), and the solid content mass ratio of starch to the surface sizing agent is 98: 2. In the same manner as in Example 8, newsprint for offset printing was produced.

Tables 1 and 2 show the measurement results of water absorption time and Nepari strength of the newspapers for offset printing obtained in Examples 1 to 8 and Comparative Examples 1 to 10, and the evaluation results of piling. Each evaluation was performed as follows.
(Water absorption time)
JAPAN TAPPI Paper Pulp Test Method No. In accordance with 32-2: 2000 “Paper—Water Absorption Test Method—Part 2: Dropping Method”, an average value of 5 μl of the amount of dripped water measured twice each on the front and back sides was taken as the water absorption time.
(Measurement of Neppari strength)
Cut two newspapers for offset printing 1 inch wide x 19 cm long, float the coated surfaces on a water surface at a temperature of 20 ° C for 5 seconds, and then immediately coat the coated surfaces (wet coated surface and wet coated surface) Adhere. Subsequently, the backing sheet is overlapped on both outer sides, passed twice through a roll at a nip pressure of 40 kgf / cm, and conditioned at 23 ° C. and 50% RH for 24 hours. The peel strength was measured with a tensile tester under conditions of a pulling speed of 100 mm / min.
(Piling evaluation)
Using an ink having a tack value of 13, printing is performed with an RI printing test machine, the ink remaining on the blanket is transferred to the coated paper, the white spots are observed, and ◎ excellent, ◯ good, × bad. Rated by stage.

As shown in Table 1, according to the embodiment of the present invention, it is possible to obtain offset printing newsprint paper that has low Nepari strength and does not cause piling.
On the other hand, as shown in Table 2, Comparative Example 1 is an example in which the amount of the internally added sizing agent was small, and the evaluation of piling is poor because the water absorption time is short.
Comparative Example 2 is an example in which the amount of the internal sizing agent was large. The sizing degree was high, and the water absorption time was as long as 213 seconds exceeding the range defined in the present invention.
Comparative Example 3 is an example in which an acidic rosin sizing agent is used as the internally added sizing agent. The sizing degree is low, and the water absorption time does not reach the range defined by the present invention, so that the evaluation of piling is poor.
Comparative Example 4 is an example in which no internal sizing agent was added, and the degree of sizing was low as in Comparative Example 3, and the evaluation of piling was poor because the water absorption time did not reach the range specified in the present invention. .
In Comparative Example 5, since the viscosity of starch is as high as 7.5 mPa · s, the Nepari strength is as high as 65 mN / 30 mm, and it is expected that Nepari trouble is likely to occur.
Comparative Example 6 is an example in which a styrene-based surface sizing agent is used as a surface sizing agent compared to Comparative Example 5, and the Nepari strength is as high as 78 mN / 30 mm, which is likely to cause Nepari trouble.
Comparative Example 7 is an example in which a low-viscosity starch was applied as compared to Comparative Example 6, but because a styrene-based surface sizing agent was used as the surface sizing agent, the Neppari strength was lower than Comparative Example 6, but 57 mN / 30 mm. It is a little expensive, and it is expected to easily cause trouble.
In Comparative Example 8, the ratio by mass of the solid content of the starch and the surface sizing agent is 64:36, and the ratio of the surface sizing agent is high. It has occurred.
Comparative Example 9 is an example in which the starch coating amount is reduced. Since the starch coating amount does not reach the range defined in the present invention, the evaluation of the pile is poor because the surface strength of the paper is low.
In Comparative Example 10, since the starch coating amount is high beyond the range defined in the present invention, the Nepari strength is as high as 76 mN / 30 mm, and it is expected that Nepari trouble is likely to occur.

Claims (2)

A low-viscosity starch having a B-type viscosity of 7 mPa · s or less at 50 ° C. and 7% on both sides of a base paper to which 0.1 to 0.4% by mass of a neutral rosin sizing agent has been added ; The surface treatment agent having a pigment as a main component is applied and dried, the coating amount of the pigment is 0.01 to 0.3 g / m 2 on one side, the Neppari strength is 50 mN / 30 mm or less, the water absorption time (JAPAN) Newsprint paper for offset printing, characterized in that the amount of dripping water is 5 to 30 seconds in accordance with TAPPI No. 32-2, 30 to 200 seconds.   The coating amount of the low-viscosity starch is 0.2 to 1.0 g / m 2 on one side, and the mass ratio of the low-viscosity starch and the olefin-based surface sizing agent contained in the surface treatment agent is in the range of 99: 1 to 70:30. The newsprint for offset printing according to claim 1, wherein the newsprint is provided.