JP2006257599A - Paper surface treatment agent and offset printing paper coated therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a paper surface treatment agent affording high surface strength, causing no sticking trouble in making an offset printing even in case the agent is applied in an amount enough to prevent paper dust emission, and capable of imparting paper with sufficient water absorption resistance, and to obtain offset printing paper, especially newsprint paper for offset printing use, having high surface strength and water absorption resistance and low surface tackiness and causing no sticking trouble. <P>SOLUTION: The high-performance paper surface treatment agent having the above-mentioned advantages is obtained by including, as the essential components, an aqueous macromolecular material, a polyethylene glycol 10,000-30,000 in weight-average molecular weight and a surface sizing agent ≥0.4 meq/g in cationization degree. The offset printing paper having the above advantages is obtained by coating the surface of offset printing base paper with the paper surface treatment agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface treatment agent with less nappari trouble when printing offset printing paper coated with a surface treatment agent containing a water-soluble polymer substance, and further, the surface treatment agent is applied to the surface of the base paper, The present invention relates to offset printing paper with little net pal trouble, particularly newsprint paper for offset printing.

  In recent years, with increasing awareness of environmental issues, efforts are also being made in the paper industry to increase the utilization rate of used paper as a raw material for paper making from the standpoint of resource saving. However, newspaper printing paper manufactured using waste paper pulp containing a large amount of fine fibers as a raw material has a problem that paper dust is generated during printing.

In addition, newspaper printing paper has shifted from ultra-light paper with a basis weight of 43 g / m ² to ultra-light paper with a basis weight of 40 g / m ² , so it is an important paper quality such as newspaper printing paper. Transparency tends to decrease. Therefore, a treatment for maintaining the opacity is performed by increasing the blending ratio of the filler. However, this blended filler also causes paper dust during printing.

  In order to reduce paper dust generated at the time of printing, in newspaper printing paper, etc., strength is increased by applying a surface treatment agent mainly composed of starches such as oxidized starch to the paper surface with a gate roll coater or the like. This improves the amount of paper dust generated. In addition, in printing paper such as high-quality paper and medium-quality paper, it is a common practice to apply a surface treatment agent such as oxidized starch to the paper surface in order to improve printability and the like.

  Although the appropriate coating amount of these surface treatment agents on various printing papers varies depending on the type of paper, it is generally known that the surface strength of the paper is improved by increasing the coating amount. However, printing paper coated with a surface treatment agent so as to have a high adhesion amount, when offset printing is performed, the surface treatment agent is dissolved by the dampening water at the time of printing, resulting in stickiness on the paper. There is a concern that the printing paper may stick to the blanket or adhere to each other, that is, the so-called Nepari trouble occurs, which hinders the printing operation. In addition, when stored under high humidity conditions even after printing, there is a problem of blocking due to adhesion between papers.

  With the recent increase in four-color printing, there is a tendency for the show-through through which the printed part is seen to be worsened. For this reason, an increase in internal fillers and a shift to fillers exhibiting high opacity are in progress. As a result, the water absorption is remarkably lowered and the pile at printing is increased. In order to prevent this, the amount of surface paper strength agent such as starch tends to increase, and Nepari trouble is more likely to occur.

  Furthermore, due to the recent spread of four-color printing, the printing cylinder comes into contact with the paper four times, so that the amount of dampening water transferred increases, causing problems such as misregistration, poor wetting, and reduced tension. It was. In order to prevent these troubles, a sizing agent has been internally or externally added to the paper to impart water absorption resistance. As a recent trend, pitch troubles tend to occur frequently in the papermaking system when a sizing agent is added as the deinking pulp blending ratio increases and the papermaking speed exceeds 1500 m / min. Therefore, in order to prevent pitch trouble, the method of imparting water absorption resistance to paper has been changed from adding a sizing agent to adding it externally.

  However, externally adding a sizing agent is effective in preventing the above-mentioned examination deviation, poor wet inking, and the problem of reduced tension, but the surface sizing agent is dissolved by dampening water during printing, and starch is added. When the surface paper strength agent and the surface sizing agent are used in combination, there is a problem that the Nepari trouble is remarkably increased as compared with the case where the surface paper strength agent is applied alone.

  As a means for solving such a paper Nepari trouble, a method in which a substituted succinic acid is mixed with a surface treatment agent as a Nepari inhibitor has been proposed (see Patent Document 1). However, if sufficient water absorption resistance is to be imparted, there is a problem that the generation of bubbles and wrinkles increases. In addition, a paper coating agent with less Nepari trouble containing a polyvinyl alcohol resin (component A), polyethylene glycol (component B) and a compound (component C) composed of ethylene oxide units and propylene oxide units has been proposed ( (See Patent Document 2). However, with such a combination, it is difficult to impart sufficient water absorption resistance, and the generation of bubbles is remarkable. In addition, a surface paper quality improver that is composed of polyalkylene glycol and an anionic polyacrylamide resin and has excellent surface strength and low tackiness when wet has been proposed (see Patent Document 3). However, in this combination, when an anionic surface sizing agent is used in combination, sufficient water absorption resistance cannot be imparted, and bubbles are often generated. Furthermore, polyethylene glycol and / or a polyoxyethylene / polyoxypropylene copolymer has been proposed as an anti-Nepari agent that does not inhibit the effect of the surface sizing agent (see Patent Document 4). However, in the situation where high water resistance is required for newspaper printing paper due to the recent spread of four-color printing, the surface sizing agent described in Patent Document 4 cannot provide sufficient water absorption.

Japanese Patent Laid-Open No. 6-929595 (Claim 1) JP 2000-239991 (Claim 1) Japanese Patent Laid-Open No. 9-217294 (Claim 1) Japanese Patent Application No. 2002-334309 (Claim 1)

  The problem of the present invention is that a desired surface strength is obtained, and even when a sufficient amount of a surface treatment agent is applied to prevent the generation of paper dust, no troubles occur during offset printing, and Provide surface treatment agent that provides sufficient water absorption resistance, and provide offset printing paper, especially newsprint paper for offset printing, that has high surface strength, high water absorption resistance, low surface tackiness, and no rippling problems It is to be.

  By containing at least an aqueous polymer material, polyethylene glycol having a weight average molecular weight of 10,000 to 30,000, and a surface sizing agent having a cationization degree of 0.4 meq / g or more as components of the surface treatment agent, the surface strength can be increased. A high-performance surface treatment agent that is high, does not cause Nepari trouble, and has high water absorption resistance can be obtained. Further, by applying the surface treatment agent to the surface of the base paper for offset printing, an offset printing paper having a high surface strength, no rip-off trouble, and high water absorption resistance can be obtained.

  The surface treatment agent of the present invention is a high-performance surface treatment agent that, when applied to the surface of a base paper, has high surface strength, no Nepari trouble, and high water absorption resistance. Further, the offset printing paper in which the surface treatment agent is applied to the surface of the base paper has an effect that the surface strength is high, there is no netpal trouble, and the water absorption resistance is high.

The surface treatment agent of the present invention will be described below. The surface treatment agent of the present invention contains at least the following components (1) to (3), and makes it possible to achieve both of imparting water absorption resistance to offset printing paper and lowering the Nepari strength. .
(1) Water-soluble polymer substance
(2) Polyethylene glycol having a weight average molecular weight of 10,000 to 30,000
(3) Surface sizing agent with a degree of cationization of 0.4 meq / g or more

The Nepari strength is an index indicating the surface tackiness when the printing paper is wet, and is measured by the method described below.
<Measurement method of Nepari strength>
Cut off two sheets of offset printing paper coated with a surface treatment agent into 4 x 6 cm, soak the coated surfaces in water at a temperature of 20 ° C for 5 seconds, and then adhere the coated surfaces to each other. Next, offset printing paper base paper is stacked on both sides of the outside, passed through a roll at a pressure of 50 kg / m ² , conditioned at 25 ° C and 60% RH for 24 hours, and cut into a 3 x 6 cm sample piece Measure with a tensile tester at a pulling speed of 30 mm / min. The larger the measured value, the harder it is to peel off (in other words, the higher the surface tackiness).

  In order to improve the surface strength of the offset printing paper, the surface treatment agent of the present invention needs to contain a water-soluble polymer substance. Examples of water-soluble polymer substances include starch, enzyme-modified starch, oxidized starch, esterified starch (such as phosphate esterified starch), etherified starch (such as hydroxyethylated starch), dialdehyde starch, and cationized starch. Starches such as, fully saponified polyvinyl alcohol, polyvinyl alcohols such as partially saponified polyvinyl alcohol, celluloses such as carboxymethyl cellulose and carboxyethyl cellulose, polyacrylamides such as anionic polyacrylamide, cationic polyacrylamide, and amphoteric polyacrylamide These include various natural polymer materials or synthetic polymer materials, and these can be used alone or in combination of two or more.

  The water-soluble polymer substance used in the surface treatment agent of the present invention plays a main role in terms of improving surface strength (in other words, suppressing paper dust). However, water-soluble polymer substances can cause Nepari trouble. Considering the effect of improving the surface strength and the balance with Neppari, as the water-soluble polymer, among the above examples, starches can be preferably used, among which oxidized starch, etherified starch and esterified starch are most preferred. .

  The polyethylene glycol contained in the surface treatment agent of the present invention is blended as an anti-Nepari agent. The polyethylene glycol may be polyethylene oxide which is a high molecular weight substance of polyethylene glycol. The weight average molecular weight is in the range of 10,000 to 30,000. If the weight average molecular weight is less than 10,000, the effect of decreasing the Nepari strength is reduced, and if it exceeds 30,000, there is a problem in compatibility with the surface sizing agent, and the prepared surface treatment agent cannot be stored for a long time. Bubbles may occur in the working fluid.

  The blending amount of polyethylene glycol is preferably 0.1 to 50 parts by weight and more preferably 0.5 to 30 parts by weight with respect to 100 parts by weight of the water-soluble polymer substance in terms of solid content. If the amount is less than 0.1 parts by weight, the effect of preventing rip-off is not sufficient, and adding more than 50 parts by weight does not further improve the effect. In order to obtain the desired effect of improving the surface strength, the amount of the conductive polymer needs to be greatly increased in order to obtain a desired effect of improving the surface strength.

  The surface sizing agent contained in the surface treatment agent of the present invention is a surface size composed of a hydrophobic portion and a hydrophilic portion, and is cationic. Examples of the hydrophobic part include styrene, styrene / (meth) acrylic acid ester copolymer (note that (meth) acrylic acid means “acrylic acid and / or methacrylic acid”), (meth) acrylic acid ester Styrene / (meth) acrylic acid / (meth) acrylic acid ester copolymer, styrene / maleic acid half ester copolymer, styrene / maleic acid ester copolymer, ethylene / (meth) acrylic acid copolymer, Examples include isobutylene / (meth) acrylic acid copolymer, n-butylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer, propylene / maleic acid copolymer, and ethylene / maleic acid copolymer. . Examples of the hydrophilic portion include dimethylaminoethyl methacrylate, dimethylaminomethyl methacrylate, dimethylaminopropyl methacrylate, and the like. These hydrophilic portions may be used after being quaternized with a quaternizing agent such as epichlorohydrin. The degree of cationization of the surface sizing agent is preferably 0.4 meq / g or more.

  The surface sizing agent is preferably contained in a ratio of 2 to 50 parts by weight in terms of solid content with respect to 100 parts by weight of the water-soluble polymer substance. When the content of the surface sizing agent is less than 2 parts by weight, the water absorption resistance is insufficiently imparted, and when it exceeds 50 parts by weight, the Nepari strength increases.

  As described above, the surface treatment agent of the present invention has a water-soluble polymer substance, polyethylene glycol, and a mixing ratio of the solid content weight of the surface sizing agent, with 0.1 part of polyethylene glycol to 100 parts of the water-soluble polymer substance. 50 parts and 2 to 50 parts of the surface sizing agent. Among them, the effect of promoting the improvement of water absorption resistance when polyethylene glycol is used in the range of 5.0 to 10 parts by weight with respect to 100 parts by weight of the surface sizing agent. There is.

  Further, in the surface treatment agent of the present invention, as long as the surface strength and Nepari strength are not adversely affected, preservatives, antifoaming agents, UV inhibitors, antifading agents, optical brighteners, viscosity stabilizers, lubricants, Auxiliaries such as anti-slip agents and pigments may be included.

  The surface treatment agent of the present invention is a high-performance surface treatment agent that, when applied to the surface of a base paper, has high surface strength, no nepari trouble, and high water absorption resistance. It is suitably used for manufacturing newsprint paper.

  The offset printing paper of the present invention will be described below. By applying the above-mentioned surface treatment agent to the base paper for offset printing and drying, an offset printing paper having high surface strength, no netpal trouble, and high water absorption resistance can be manufactured.

  The offset printing paper of the present invention may be fine paper or medium paper. The raw material pulp may be pulp that is usually used for paper, and is not particularly limited. Chemical pulp (CP), groundwood pulp (GP), chemiground pulp (CGP), refiner ground pulp (RGP), thermo Pulp of various manufacturing methods such as mechanical pulp (TMP), chemithermomechanical pulp (CTMP), semi-chemical pulp (SCP), etc. ) And the like are appropriately blended according to the type of paper.

  The base paper of the offset printing paper of the present invention may be acid papermaking, neutral paper, or alkaline papermaking.

  For the base paper of offset printing paper produced by the acid papermaking method, if necessary according to the type of paper, known internal sizing agents for acidic papermaking such as rosin sizing agent, reinforced rosin sizing agent and synthetic sizing agent can be used. In addition, it is possible to use a filler that is stable even when the papermaking pH is in an acidic range, specifically, inorganic fillers such as clay, calcined kaolin, deramikaolin, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, and urea-holimarin. Organic fillers such as resins, polystyrene resins, phenol resins, and fine hollow particles can be used alone or in appropriate combination of two or more.

  For base paper of offset printing paper manufactured by the neutral papermaking method, if necessary depending on the type of paper, a known internally added neutral sizing agent, alkyl ketene dimer (AKD) sizing agent, alkenyl succinic anhydride (ASA) sizing agent, neutral rosin sizing agent can be used, and fillers include calcium carbonate, magnesium carbonate, barium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, clay, calcined kaolin, delamination Inorganic fillers such as kaolin, titanium dioxide, zinc oxide, silicon oxide, and amorphous silica, urea-holimarin resin, polystyrene resin, phenol resin, and fine hollow particles can be used. As calcium carbonate, light calcium carbonate is preferably used. A light calcium carbonate-silica composite is also preferably used. Examples of the light calcium carbonate-silica composite include the light calcium carbonate-silica composite described in Japanese Patent Application No. 2003-212539 and Japanese Patent Application No. 2004-83767 filed by the present applicant.

  When making base paper, various nonionic, cationic retention agents, freeness improvers, paper strength improvers, and other internally used auxiliary additives for papermaking are appropriately selected and used as necessary. Is done. Further, for example, sulfuric acid bands, aluminum chloride, sodium aluminate, basic aluminum compounds such as basic aluminum chloride and basic polyaluminum hydroxide, water-soluble aluminum compounds such as water-degradable alumina sol, sulfuric acid A polyvalent metal compound such as ferrous sulfate or ferric sulfate, silica sol, or the like may be internally added. Other starches for papermaking, various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide, polyamine resin, polyamine, polyethyleneimine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, hydrophilic cross-linked polymer Various compounds such as particle dispersions and derivatives or modified products thereof can be used. Furthermore, internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be appropriately added depending on the intended use.

  The apparatus used for applying the surface treatment agent is not particularly limited, and is a size press coater, tab size, calendar size, wire bar coater, air knife coater, roll coater (e.g., gate roll coater), blade coater (e.g., Spray blade coater, etc.). Among these, it is preferable to use a blade coater or a roll coater because the surface treatment agent can be applied at a high speed and with a high concentration, the yield on the paper layer surface is high, and the amount of drying heat is small. Also, among roll coaters, gate roll coaters can be coated on both sides simultaneously using different types of surface treatment agents, and can improve printability such as smoothness, whiteness, glossiness, and ink acceptability. Furthermore, since high concentration coating is possible, moisture movement into the paper layer is small, which is particularly preferable from the viewpoints of paper breakage during application and generation of wrinkles.

  The concentration and viscosity when applying the surface treating agent liquid of the present invention to the surface of the offset printing paper base paper are not particularly limited, but the concentration is usually 0.5 to 20 solids by weight, preferably 1 to 15 solids. The weight% and the viscosity are 1,000 cps (35 ° C., B-type viscosity) or less, preferably 200 cps or less.

The coating amount of the surface treatment agent of the present invention varies depending on the type of offset printing paper, usually in the range of 0.005~5.0g / m ^2, to regulate preferably such that 0.01 to 2.0 g / m ² It is good.

  After applying the surface treatment agent to the base paper of the offset printing paper, the paper dried by the dryer part is calendered for the purpose of smoothing the paper surface, if necessary. The apparatus is not limited, and examples thereof include a normal hard nip calender, a soft nip calender, a high temperature soft nip calender, and a shoe calender.

  As described above, it is possible to obtain an offset printing paper having high surface strength, high water absorption resistance, low surface tackiness, and no occurrence of Nepari trouble.

  Since the effect of the surface treating agent of the present invention is remarkably recognized when the offset printing paper of the present invention is a newspaper for offset printing, the following is mentioned.

Raw pulp used for newsprint base paper for offset printing is ground pulp (GP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), mechanical pulp (MP) such as semi-chemical pulp (SCP), Chemical pulp (CP) typified by kraft pulp (KP), deinked pulp (DIP) obtained by deinking waste paper containing these pulps, either alone or arbitrarily, depending on the quality desired by the user Are used by appropriately mixing at a ratio of In general, as the DIP content increases, Nepari tends to deteriorate, but this is due to the fact that DIP contains sticky foreign substances and that the content of virgin mechanical pulp containing resin acid analogues decreases. One is considered. Since the surface treatment agent of the present invention shows a good anti-Nippari-preventing effect even when the DIP content is in the high range of 50 to 100% by weight, the DIP content may be added within an arbitrary range. The basis weight of the newsprint base paper is not particularly limited, but is 34 to 45 g / m ² .

  The base paper for offset printing newsprint of the present invention may be produced by either the acid papermaking method or the neutral papermaking method, but the newsprint paper produced by the neutral papermaking method has optical quality such as whiteness and opacity, Furthermore, the neutral papermaking method is preferred because the printability such as the vividness of color printing is much better than the acid papermaking.

  The newsprint for offset printing of the present invention may be blended with or without a filler, but it is preferable to blend a filler from the viewpoint of increasing opacity. When blending a filler, the filler generally used in acidic papermaking or neutral papermaking can be used, and is not particularly limited. For example, in neutral papermaking, clay, calcined kaolin, deramikaolin, heavy calcium carbonate, light calcium carbonate, light calcium carbonate-silica composite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, white carbon, etc. Inorganic fillers such as amorphous silica, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, urea-formalin resin, polystyrene resin, phenol resin, vinyl chloride resin, melamine resin, styrene-butadiene copolymer Organic fillers such as system resins and fine hollow particles are used alone or in appropriate combination of two or more. Among these, light calcium carbonate and light calcium carbonate-silica composite are preferably used. Examples of the light calcium carbonate-silica composite include the light calcium carbonate-silica composite described in Japanese Patent Application No. 2003-212539 and Japanese Patent Application No. 2004-83767 filed by the present applicant. Further, in acidic papermaking, a filler obtained by removing acid-soluble ones from the filler used in the neutral papermaking is used, and these are used alone or in combination of two or more as appropriate.

  Further, an internal sizing agent for publicly known acidic papermaking and neutral papermaking may be blended. For example, in acid papermaking, various rosin-based sizing agents, emulsion sizing agents, etc., and in neutral papermaking, alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), neutral rosin sizing agent, etc. are mentioned. .

  Moreover, the chemicals for papermaking can be added suitably as needed. Examples of papermaking chemicals include polyacrylamide polymers, polyvinyl alcohol polymers, cationized starch, urea-formalin resin, melamine-formalin resin and other paper strength enhancers, and copolymers of acrylamide and aminomethylacrylamide. Freeness improver or yield improver such as salt, cationized starch, polyethyleneimine, polyethylene oxide, acrylamide-sodium acrylate copolymer, aluminum sulfate (sulfate band), UV inhibitor, fading inhibitor, defoamer, slime You may contain papermaking adjuvants, such as a control agent.

The apparatus used for applying the surface treatment agent is the same as that for the offset printing paper described above. The concentration and viscosity of the surface treatment agent when applied to the base paper surface of newsprint paper for offset printing are not particularly limited, but usually the concentration is 0.5 to 20 solids by weight, preferably 1 to 15 solids by weight. The viscosity is 1,000 cps (35 ° C., B-type viscosity) or less, preferably 200 cps or less. The coating amount of the surface treatment agent is usually in the range of 0.005~5.0g / m ^2, and it is preferably adjusted to a 0.01 to 2.0 g / m ^2. After the surface treatment agent is applied to the newsprint base paper for offset printing, the paper dried by the dryer part is calendered for the purpose of smoothing the paper surface, if necessary. It is the same as printing paper.

  As described above, it is possible to obtain an offset printing newsprint having high surface strength, high water absorption resistance, low surface tackiness, and no occurrence of Nepari trouble. The other paper quality of this newsprint for offset printing should just have the physical property of newsprint for normal offset printing. In the printing of newsprint for offset printing, operability is regarded as important, and a large amount of printing must be performed in a short time. Therefore, by applying the surface treatment agent of the present invention to newsprint for offset printing, the Nepari strength can be lowered and water absorption resistance can be simultaneously imparted. Therefore, even when printing using an offset printing machine, the problem of sticking to the blanket can be prevented by improving the adhesiveness of the paper surface due to transfer of dampening water during offset printing. Interruption can be prevented, and the printing work efficiency can be improved.

  Regarding the use of the paper obtained by applying the surface treating agent of the present invention, in addition to the above-mentioned offset printing paper and offset printing newsprint paper, various papers such as notebook paper, book paper, form paper, PPC paper, etc. Can also be used.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In addition, unless otherwise indicated, the part and% in each example represent a weight part and weight%, respectively. The following newsprint base paper for offset printing was used in Examples and Comparative Examples.
<Newspaper base paper making>
5 parts of softwood kraft pulp, 18 parts of thermomechanical pulp, and 77 parts of deinked waste paper pulp were mixed and disaggregated with a refiner to adjust the Canadian standard freeness (CSF) to 110 ml. Neutral newspaper for offset printing with a basis weight of 42 g / m ² after adding light calcium carbonate as a filler to this pulp slurry so that it becomes 11% per bone dry pulp weight and making paper with a twin wire type paper machine. Paper base paper was obtained.

[Example 1]
Hydroxyethylated starch (trade name: Ethylex2025, manufactured by Stayley Co., Ltd.) and cationic styrene sizing agent (trade name: SS2767, manufactured by Seiko PMC Co., Ltd., degree of cationization: 0.7 meq / g) as surface treatment agents Mixing so that the solid content weight ratio with respect to starch is 15%, and further adding polyethylene glycol having a weight average molecular weight of 20,000 as an anti-Neppari agent to 1% solid content weight ratio with respect to starch, Dilution was performed to obtain a surface treatment agent coating solution having a solid concentration of 7.0%. Apply the resulting surface treatment agent coating solution on both sides of the above newsprint base paper using a gate roll coater at a coating speed of 1200 m / min and a target of 0.60 g / m ² And dried to obtain newsprint for offset printing.

[Example 2]
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that polyethylene glycol having a weight average molecular weight of 20,000 was added as an anti-Nepari agent so that the solid content weight ratio was 2% with respect to starch.

[Example 3]
Newsprint paper for offset printing in the same manner as in Example 1 except that the cationic styrene-based sizing agent for surface treatment was trade name NC-77 (manufactured by Harima Chemical Co., Ltd., cationization degree: 0.6 meq / g). Got.

[Example 4]
Newspaper for offset printing in the same manner as in Example 1 except that the cationic styrene sizing agent for the surface treatment was trade name LC-5 (manufactured by Harima Kasei Co., Ltd., cationization degree: 1.1 meq / g). Got.

[Comparative Example 1]
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that polyethylene glycol, which is a Nepari inhibitor, was not added.

[Comparative Example 2]
Newsprint paper for offset printing was obtained in the same manner as in Example 3 except that polyethylene glycol, which is a Neppari inhibitor, was not added.

[Comparative Example 3]
Newsprint paper for offset printing was obtained in the same manner as in Example 4 except that polyethylene glycol as an anti-Nepari agent was not added.

[Comparative Example 4]
Polyethylene glycol having a weight average molecular weight of 2,000 as an anti-Nepari agent is added to the starch so that the solids weight ratio is 3%, and as the surface sizing agent, an anionic styrenic sizing agent (trade name: KN-520, Harima) Newspaper for offset printing was obtained in the same manner as in Example 1 except that Kasei Co., Ltd. was used.

[Comparative Example 5]
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that saponified alkenyl succinic anhydride (trade name: M-150-35, manufactured by Seiko Chemical Industry Co., Ltd.) was used as the Nepari inhibitor.

[Comparative Example 6]
Newsprint paper for offset printing was obtained in the same manner as in Example 1 except that polyethylene glycol having a weight average molecular weight of 5,000 as an Nepari inhibitor was added to starch so that the weight ratio of solid content was 1%.

For the newspapers for offset printing of Examples 1 to 4 and Comparative Examples 1 to 6, the drip water absorption, the Nepari strength, and the amount of bubbles generated were measured by the methods shown below, and the results are shown in Table 1.
・ Measurement of drip water absorption: According to Japan TAPPI No.33 (Test method for water absorption rate of absorbent paper), measurement was performed with a drop water volume of 1 μl.
-Measurement of Nepari strength: Two newspapers for offset printing were cut into 4 × 6 cm pieces, and the coated surfaces were immersed in water at a temperature of 20 ° C. for 5 seconds, and the coated surfaces were brought into close contact with each other. Newspaper base paper was placed on both sides of the outside, passed through a roll at a pressure of 50 kg / m ² , and conditioned at 25 ° C. and 60% RH for 24 hours. After cutting into 3 × 6 cm sample pieces, the peel strength was measured with a tensile tester under the conditions of a tensile speed of 30 mm / min. The larger the measured value, the harder it is to peel off (in other words, the higher the surface tackiness), that is, the higher the Nepari strength.
-Foam generation amount: Evaluated by visual observation, it was judged that ○ was small, Δ was medium, and X was large.

As shown in Table 1, the newspapers for offset printing coated with the surface treatment agents of Examples 1 to 4 of the present invention were compared with Comparative Examples 1 to 3 and an anionic sizing agent that were not coated with the Nepari inhibitor. Compared to Comparative Example 4 mixed and coated, Comparative Example 5 coated with fatty acid saponified product as an anti-Nepari inhibitor, and Comparative News 6 coated with low molecular weight polyethylene glycol, the Neppari strength is low, The drip water absorption is high, the generation of bubbles is small, and the operability is good.

Claims (6)

A surface treatment agent for paper, which comprises at least the following components (1) to (3):
(1) Water-soluble polymer substance
(2) Polyethylene glycol having a weight average molecular weight of 10,000 to 30,000
(3) Surface sizing agent with a degree of cationization of 0.4 meq / g or more   The mixing ratio of the solid content weight of the water-soluble polymer substance, polyethylene glycol, and surface sizing agent is 0.1 to 50 parts of polyethylene glycol and 2 to 50 parts of surface sizing agent with respect to 100 parts of the water-soluble polymer substance. The surface treatment agent according to claim 1, wherein Offset printing paper, which is an offset printing paper, which is obtained by applying and drying a surface treatment agent containing at least the following components (1) to (3) on at least one surface of an offset printing paper base paper.
(1) Water-soluble polymer substance
(2) Polyethylene glycol having a weight average molecular weight of 10,000 to 30,000
(3) Surface sizing agent with a degree of cationization of 0.4 meq / g or more   The mixing ratio of the solid content weight of the water-soluble polymer substance, polyethylene glycol, and surface sizing agent is 0.1 to 50 parts of polyethylene glycol and 2 to 50 parts of surface sizing agent with respect to 100 parts of the water-soluble polymer substance. The offset printing paper according to claim 3, wherein:   The offset printing paper according to claim 3 or 4, wherein the offset printing paper is newspaper for offset printing. The offset printing paper according to claim 4 or 5, wherein the offset printing paper is neutral papermaking.