JP4381172B2 - Newspaper printing paper - Google Patents

Description

  The present invention relates to a newspaper printing paper that is bulky and has a small decrease in stiffness, a high opacity, a high friction coefficient, and an excellent printing workability.

  Users are demanded to reduce the weight of newspaper printing paper in terms of effective use of paper pulp produced from forest resources and reduction of logistics costs. On the other hand, with an increase in environmental protection in recent years, it is also desired to increase the distribution of used paper pulp to newspaper printing paper. However, the increase in the distribution of waste paper pulp, which has a high density and low opacity in the trend of weight reduction, is limited from the viewpoint of the bulk and opacity of newspaper printing paper. That means was necessary.

  As a method of increasing the bulk of paper, that is, reducing the density, paper pulp has been studied. Generally, wood pulp is used for paper pulp. However, in order to reduce the density, wood is polished with a grinder rather than chemical pulp extracted from lignin, which is a reinforcing material in wood fibers, with chemicals. A refined mechanical pulp or a mechanical pulp such as a thermomechanical pulp that refines wood with a crushed ground pulp or refiner has a more rigid fiber and is effective in reducing the density. However, although groundwood pulp has a high specific scattering coefficient and contributes high opacity to paper, it has low strength and it has become difficult to secure logs as raw materials. Also, ground pulp is generally less bulky than refiner mechanical pulp. On the other hand, conifer refiner pulp is bulky and strong, but has a low specific scattering coefficient and does not contribute much to the opacity of paper. Among mechanical pulps, thermomechanical pulp has a long fiber length and high rigidity, but the problem is that the smoothness of the manufactured sheet is lowered.

  As a conventional technique for increasing the bulk of paper, there is a method of using a bulky pulp composition obtained by reacting a mixture of pulp and hydrophobic fibers with a crosslinking agent (see Patent Document 1). In addition, there is a method for producing a bulky pulp sheet by mixing cellulose pulp, a specific form of polyester composite fiber, and a heat-fusible binder (see Patent Document 2). However, the use of cross-linked pulp, synthetic fibers, etc. has the problem of making paper impossible to recycle. Further, there is a technique for producing a bulky neutral paper by filling hollow spherical vaterite type calcium carbonate (see Patent Document 3), but there is a problem that it is a special filler. In addition, there is a method of producing a low-density bulky paper by making paper from pulp and heat-expandable particles (see Patent Document 4). The method using foamable particles has a problem that the paper strength is remarkably lowered. In addition, there is a method using bacterial cellulose and expandable particles (see Patent Document 5), but a special cellulose called bacterial cellulose must be used, which is not practical.

  Further, in the method using a surfactant, a bulking agent for paper containing a specific alcohol and / or a polyoxyalkylene adduct thereof is disclosed (see Patent Document 6). There is also a method using a nonionic surfactant (see Patent Document 7). Further, a paper bulking agent comprising a polyhydric alcohol and a fatty acid ester compound (see Patent Document 8) is disclosed, and there is a technique in which this paper bulking agent is applied to paperboard (see Patent Document 9).

  By using these known bulking agents, it is possible to make the paper bulky, but some known bulking agents simultaneously cause a sharp decrease in the coefficient of friction of the paper. When offset printing is performed on paper with such a reduced coefficient of friction, there is a problem that troubles in printing runnability such as paper run-off, which is called paper flow, and tension fluctuation at the time of paper change occur.

  Non-surfactant-based bulking agent technology discloses a paper bulking agent containing at least one compound selected from a cationic compound having a specific structure, an amine, an acid salt of an amine, and an amphoteric compound. (See Patent Document 10). There is also a bulking agent of the fatty acid polyamide polyamine type. However, when these bulking agents are added, it is possible to make the paper bulky, but at the same time, a remarkable reduction in paper strength and stiffness occurs.

Patent No. 2903256 Japanese Patent No.2591685 Japanese Patent No. 1755152 Japanese Patent Laid-Open No. 5-230798 Japanese Patent Laid-Open No. 11-200282 International Publication No. 98/03730 Pamphlet JP 11-200283 A Patent No. 2971447 Specification Patent No. 3041294 JP 11-269799 A

  As described above, there has been a demand for the development of newspaper printing paper that is bulky, has little reduction in stiffness, has high opacity, has a high friction coefficient, and has excellent printing workability.

  An object of the present invention is to provide a newspaper printing paper that is bulky and has a small decrease in stiffness, a high opacity, a high friction coefficient, and an excellent printing workability.

  A synthetic cationic polymer having a 7 wt% aqueous solution viscosity at 50 ° C of 20 mPa · s or more and a nitrogen content of 1.0 wt% or less, and a glass transition point having a structural unit derived from a vinyl monomer of 90 ° C or less Paper stock containing 0.1 to 10% solid content by weight of raw material pulp with an internal paper quality improver consisting of a polymer emulsion containing polymer particles, and a dynamic friction coefficient of 0.20 to 0.60 and an opacity of 90 Get more than% newspaper printing paper.

  The newspaper printing paper of the present invention has the effect that it is bulky, has a small decrease in stiffness, has a high opacity, has a high friction coefficient, and is excellent in printing workability.

  The paper quality improver used in the present invention is a substance described in Japanese Patent Application No. 2002-252659, the viscosity of a 7% by weight aqueous solution at 50 ° C. is 20 mPa · s or more, and the nitrogen content is 1.0% by weight or less. An internal paper quality improver comprising a polymer emulsion containing a synthetic cationic polymer and polymer particles having a structural unit derived from a vinyl monomer and having a glass transition point of 90 ° C. or lower.

(Synthetic cationic polymer)
The synthetic cationic polymer has a nitrogen content (N%: analyzed by Kjeldahl method) of preferably 0.05% by weight or more, more preferably 0.07% by weight or more, particularly preferably 0.1% by weight or more, and 1.0% by weight or less. Preferably, 0.9% by weight or less is more preferable, and 0.7% by weight or less is particularly preferable. A polymer having a cationic group is preferable so that the nitrogen content is in this range. For the introduction of the cationic group, a cationic monomer may be polymerized, or a cationic group may be introduced into the polymer by reaction or the like. When the nitrogen content is in this range, the effect of improving the paper quality such as rigidity and bulk of the present invention can be sufficiently obtained.

  As the cationic group, an ammonium group or an amino group may be neutralized with hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, maleic acid, fumaric acid, citric acid, tartaric acid, adipic acid, lactic acid or the like.

  When the molecular weight of the synthetic cationized polymer is expressed by replacing it with aqueous solution viscosity, in a B-type viscometer (60 rpm, 50 ° C.), the 7 wt% aqueous solution viscosity is preferably 20 mPa · s or more, preferably 40 mPa · s or more. The upper limit is preferably 10,000 mPa · s or less, more preferably 8,000 mPa · s or less, and particularly preferably 5,000 mPa · s or less.

  As the synthetic cationic polymer, a cationic polymerized unit derived from a monomer having a polymerizable unsaturated group (for example, vinyl group, vinylene group, vinylidene group, allyl group, etc.), preferably general formulas (1) to ( And a cationic polymer having one or more cationic polymer units selected from the group consisting of (meth) acrylic acid type, styrene type, vinyl pyridine type, vinyl imidazoline type and diallylamine type polymer units represented by 5).

(Where
R ¹ : hydrogen atom or methyl group R ² , R ³ , R ⁴ : the same or different, hydrogen atom, alkyl group having 1 to 22 carbon atoms or substituted alkyl group Y: —O— or —NH—
Z: an alkylene group having 1 to 12 carbon atoms or a hydroxyalkylene group X ⁻ : an anion. ).

  Z is preferably an alkylene group or a hydroxyalkylene group having 2 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, and particularly preferably a hydroxypropylene group.

R ² , R ³ and R ⁴ are preferably an alkyl group having 1 to 12 carbon atoms, more preferably 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, an i-propyl group, and an n-propyl group. It is done.

Specific examples of X ⁻ include halogen ions such as chlorine, iodine and bromine, and organic anions such as sulfuric acid, sulfonic acid, methyl sulfuric acid, phosphoric acid and nitric acid.

(Where
R ^5: a hydrogen atom or a methyl group R ^6: an alkylene group R ⁷ having 1 to 3 carbon atoms, R ^8, R ^9: the same or different, carbon atoms which may have a hydrogen atom or a substituent 1 ~ 22 alkyl groups.
X ⁻ : The same meaning as described above. )

R ⁶ is preferably a methylene group. R ⁷ , R ⁸ and R ⁹ are preferably alkyl groups having 1 to 12 carbon atoms, more preferably 1 to 3 carbon atoms, such as a methyl group, an ethyl group, an i-propyl group, and an n-propyl group. Is mentioned. Substituents include hydroxyl groups and halogen atoms. Specific examples of X ⁻ include those described above. The styrene polymer unit preferably has a substituent at the para position.

(Where
R ¹⁰ : hydrogen atom or methyl group R ¹¹ : hydrogen atom or alkyl group having 1 to 22 carbon atoms X ⁻ : the same meaning as described above. )

R ¹¹ is preferably an alkyl group having 1 to 12 carbon atoms, more preferably 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, an i-propyl group, and an n-propyl group, and particularly preferably. It is a methyl group. Specific examples of X ⁻ include those described above.

(Where
R ¹² : hydrogen atom or methyl group R ¹³ : hydrogen atom or alkyl group having 1 to 3 carbon atoms R ¹⁴ : hydrogen atom or alkyl group having 1 to 22 carbon atoms X ⁻ : has the same meaning as described above. )

R ¹³ is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom. R ¹⁴ is preferably an alkyl group having 1 to 12 carbon atoms, more preferably 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, an i-propyl group, and an n-propyl group, and particularly preferably. It is a methyl group. Specific examples of X- include those mentioned above.

(Where
R ¹⁵ and R ^{16 are the} same or different and each represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.
X ⁻ : The same meaning as described above. ).

R ¹⁵ and R ¹⁶ are preferably the same or different and include a hydrogen atom, a methyl group, an ethyl group, an i-propyl group, an n-propyl group, and the like. Specific examples of X ⁻ include those described above.

  The synthetic cationic polymer is preferably a copolymer containing nonionic polymer units. The nonionic polymer unit is more preferably a hydrophilic nonionic polymer unit. Here, the hydrophilicity of the polymerized unit means that the monomer as a group from which the polymerized unit is obtained in the organic conceptual diagram-basics and applications (written by Yoshio Koda, Sankyo Publishing Co., Ltd., issued May 10, 1984). The ratio [I / O] between inorganic (I) and organic (O) means 0.60 or more, preferably 1.00 or more, more preferably 1.30 or more.

  Nonionic polymerized units can be obtained by copolymerizing with nonionic monomers. Examples of such nonionic monomers include vinyl alcohols; hydroxyalkyl groups (having 1 to 8 carbon atoms) such as N-hydroxypropyl (meth) acrylamide, hydroxyethyl (meth) acrylate, and N-hydroxypropyl (meth) acrylamide. (Meth) acrylic acid ester or (meth) acrylamide having a polyhydric alcohol such as polyethylene glycol (meth) acrylate (degree of polymerization of ethylene glycol 1 to 30); (meth) acrylamide; N-methyl Alkyl (carbon number 1-8) such as (meth) acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N-isobutyl (meth) acrylamide (Meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N -Dialkyl (total carbon number 2 to 8) (meth) acrylamide; such as diethyl (meth) acrylamide; diacetone (meth) acrylamide; N-vinyl cyclic amide such as N-vinylpyrrolidone; methyl (meth) acrylate, ethyl (meth) (Meth) acrylic acid ester having alkyl (1-8 carbon atoms) group such as acrylate, n-butyl (meth) acrylate; (meth) acrylamide having cyclic amide group such as N- (meth) acryloylmorpholine, etc. Illustrated.

  The synthetic cationic polymer preferably has a nonionic polymer unit so as to have the above-described nitrogen content.

  For the purpose of improving polymerization stability and mechanical stability, a cationic polymer may be used in combination with a nonionic polymer. The nonionic polymer is preferably a semi-synthetic water-soluble polymer such as methyl cellulose, hydroxyethyl cellulose, or soluble starch; or a synthetic water-soluble polymer such as polyvinyl alcohol obtained by polymerizing the aforementioned nonionic monomer. The amount of the nonionic polymer used is preferably 0 to 100 parts by weight, more preferably 0 to 50 parts by weight, based on 100 parts by weight of the total vinyl monomer.

(Polymer particles)
The polymer particles preferably have a Tg of 90 ° C. or lower, and more preferably 80 ° C. or lower. When the Tg of the polymer is 90 ° C. or less, the internally added paper quality improver contained in the paper efficiently melts in the paper manufacturing process, and the paper quality improving performance such as rigidity and bulk becomes good. The lower limit is not particularly limited, but is preferably −10 ° C. or higher.

  The polymer particles preferably have a structural unit derived from a vinyl monomer. The content of the vinyl monomer in the polymer particles is preferably 50 to 100 mol%, more preferably 80 to 100 mol%. As a vinyl monomer, a vinyl compound, a vinylene compound, a vinylidene compound, and a cyclic olefin are contained, What is described below is mentioned preferably.

(1) Methyl (meth) acrylate ((meth) acryl is acrylic, methacrylic or a mixture thereof; the same shall apply hereinafter), ethyl (meth) acrylate, isopropyl (meth) acrylate, (meth) acrylic acid (Meth) acrylic acid alkyl ester having an alkyl group having preferably 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms, such as butyl, isobutyl (meth) acrylate, t-butyl (meth) acrylate;
(2) Fatty acid vinyl ester comprising an ester of a linear or branched fatty acid having 1 to 18 carbon atoms, preferably 1 to 6 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl pivalate, and vinyl alcohol. ;
(3) (Meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- (meth) acrylamide-2- Anionic monomers having a polymerizable unsaturated group such as methyl propane sulfonic acid, vinyl sulfonic acid and styrene sulfonic acid, or salts thereof may be mentioned. Polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid include acid anhydrides, partial esters and partial amides or mixtures thereof. Examples of the “salt” include alkali metal salts (sodium salt, potassium salt, lithium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, barium salt, etc.), ammonium salts (quaternary ammonium salt, quaternary ammonium salt, etc. Quaternary alkyl ammonium salts, etc.). Of these, sodium salts are the cheapest and preferred.

  (4) (Meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) Polymerizable unsaturation such as acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, N-vinylpyrrolidone, N-vinylacetamide Nonionic hydrophilic group-containing monomer having a group.

  (5) Amino group having a polymerizable unsaturated group such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, etc. Specific examples of the monomer-containing monomer or its acid neutralized product or its quaternized product can be given. Preferred acids for obtaining an acid neutralized product include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, maleic acid, fumaric acid, citric acid, tartaric acid, adipic acid, lactic acid and the like. Examples of the alkylating agent include alkyl halides such as methyl chloride, ethyl chloride, methyl bromide and methyl iodide, and general alkylating agents such as dimethyl sulfate, diethyl sulfate and di-n-propyl sulfate.

  (6) Styrene.

  Of the above vinyl monomers, use of a fatty acid vinyl ester is most preferable for improving the rigidity of the paper. The polymer particles used in the present invention can be obtained by emulsion polymerization, suspension polymerization or dispersion polymerization.

(Polymer emulsion)
In the emulsion, the polymer particles described above are preferably contained in a solid content of 10 to 60% by weight, more preferably 15 to 55% by weight from the viewpoint of ease of handling. The average particle size of the polymer particles is preferably from 0.1 to 50 μm, more preferably from 0.2 to 30 μm, from the viewpoints of emulsion stability, pulp adsorption and the like.

  Furthermore, the aforementioned cationic polymer is preferably contained in the emulsion in an amount of 0.5 to 30% by weight, more preferably 2 to 25% by weight, from the viewpoint of adsorbing the polymer particles to the pulp.

  The cationic polymer is preferably 5 to 200 parts by weight, more preferably 5 to 150 parts by weight, and particularly preferably 7 to 120 parts by weight with respect to 100 parts by weight of the polymer particles. The weight of the polymer particles is the weight of all monomers constituting the polymer particles.

  The emulsion of the present invention preferably contains 40 to 90% by weight, more preferably 45 to 85% by weight of a dispersion medium. The dispersion medium is preferably water, but may contain a lower alcohol. Examples of the lower alcohol include methyl, ethyl, isopropyl alcohol having 1 to 3 carbon atoms.

  In addition to preservatives and bactericides, fillers, pigments and the like may be included as additives.

  The inventors of the present invention have studied the newspaper printing paper containing the paper quality improver and have completed the present invention.

  The present invention relates to newspaper printing paper, and as raw material pulp, chemical pulp (conifer bleached kraft pulp (NBKP) or unbleached kraft pulp (NUKP), hardwood bleached kraft pulp (LBKP)) or unbleached kraft pulp (LUKP). )), Mechanical pulp (groundwood pulp (GP), refiner mechanical pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc.), deinked pulp (DIP) are mixed in any proportion And use it. The newsprint paper of the present invention can be produced with a mechanical pulp content of 5 to 95% by weight.

  The papermaking pH of the newspaper printing paper of the present invention may be acidic, neutral, or alkaline.

  The newspaper printing paper 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, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, aluminum hydroxide, hydroxide Inorganic fillers such as calcium, magnesium hydroxide, and zinc hydroxide, and organic fillers such as urea-formalin resin, polystyrene resin, phenol resin, and fine hollow particles are used alone or in appropriate combination of two or more. 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.

  The place where the paper quality improver, sizing agent and filler are added is before the paper making process and is internally added. The place is not particularly limited as long as it is a place before the paper making process, but is preferably before a mixing chest or a secondary fan pump, and preferably before adding a yield improver.

  Even if the amount of the paper quality improver is increased beyond a certain level, the bulkiness effect is likely to reach a peak, so the paper quality improver is added to the raw material pulp in the range of 0.1 to 10 solids by weight. In order to fully develop the effect of the bulking agent without changing the paper quality (excluding bulk) so much, 0.1 to 5% by weight is preferable, and 0.1 to 2.5% by weight is more preferable.

  In the production of newspaper printing paper of the present invention, various conventionally used nonionic, cationic or amphoteric yield improvers, freeness improvers, paper strength improvers, etc. are required for papermaking internal additives. It is selected and used as appropriate according to the conditions.

  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, paper additives 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 type of the paper machine is not particularly limited, and the paper machine can be made with a public paper machine such as a long net paper machine, a gap former, or a hybrid former (on-top former). The press line pressure is used within the normal operating range. The surface treatment agent may or may not be applied. When applying the surface treatment agent, there are no particular limitations on the components of the surface treatment agent, and the size press type is also not limited, and a liquid film transfer type size press such as a 2-roll size press, a gate roll size press, or a shim sizer. Etc. can be used as appropriate. The calendar is used at a linear pressure within the normal operating range, but from the viewpoint of bulking newspaper printing paper, the linear pressure is preferably as low as possible within the range where the smoothness of the paper can be maintained. A soft calendar is preferred over a render.

  The surface treatment agent is not particularly limited, for example, raw starch, oxidized starch, esterified starch, cationized starch, enzyme-modified starch, aldehyde-modified starch, modified starch such as hydroxyethylated starch, carboxymethylcellulose, hydroxyethylcellulose, Cellulose derivatives such as methylcellulose, modified alcohols such as polyvinyl alcohol and carboxyl-modified polyvinyl alcohol, styrene butadiene copolymer, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyacrylic acid ester, Polyacrylamide or the like can be used alone or in combination. Among them, the application of hydroxyethylated starch, which is excellent in the effect of improving the surface strength, is most preferable. In addition to the above-mentioned agents, surface sizing agents such as styrene acrylic acid, styrene maleic acid, olefinic compounds, and cationic sizing agents can be applied to the surface treatment agent.

  The opacity of the newspaper printing paper of the present invention produced as described above is 90% or more. The dynamic friction coefficient is 0.20 to 0.60, preferably 0.30 to 0.60, and more preferably 0.40 to 0.60. If the dynamic friction coefficient is less than 0.20, troubles in printing running properties such as poor paper running during offset printing and tension fluctuation during paper change occur. It is difficult to make the dynamic friction coefficient more than 0.60. The opacity of newspaper printing paper is greatly affected by the type and blending ratio of the raw material pulp, the filler content, etc., and an opacity of 90% or more can be achieved by appropriately combining these. On the other hand, the dynamic friction coefficient is also greatly affected by the type and blending ratio of the raw material pulp and the filler content. Therefore, the dynamic friction coefficient can be set within a predetermined range by appropriately combining them. It should be noted that the internal additive paper quality improver used in the present invention has little influence on the dynamic friction coefficient of paper.

  The paper quality improver used in the present invention has a remarkable effect of increasing the bulk of the paper, but has a feature that there is little decrease in stiffness and high opacity. Furthermore, there is little decrease in the dynamic friction coefficient. Therefore, the paper quality improver can be highly blended, and accordingly, a newspaper printing paper with higher rigidity and lower density can be produced.

  Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified, “parts” is parts by weight and “%” is% by weight.

<Examples of emulsion production>
・ Emulsion 1 (EM-1)
In a 2 L flask equipped with a reflux condenser, dropping funnel, thermometer, nitrogen inlet, and stirrer, cationic polyvinyl alcohol [PVA C-118, N% = 0.3%, 7% aqueous solution viscosity 67 mPa · s (50 ° C, B (Type viscometer, rotor No. 1, 60 rpm), Kuraray Co., Ltd.] 70 g and ion-exchanged water 570 g were charged and heated to 90 ° C. to dissolve. After cooling, 30 g of Emulgen 150 (nonionic surfactant, 20% aqueous solution, manufactured by Kao Corporation) and 11.4 g of 4% tartaric acid (reagent, manufactured by Wako Pure Chemical Industries, Ltd.) were added (all after addition) After the pH of the system was 44.0), the mixture was stirred at 120 rpm, heated to 60 ° C. while blowing nitrogen, and held for 30 minutes. Next, 20 g of vinyl acetate (manufactured by Shin-Etsu Vinyl Acetate Co., Ltd.) and 0.2 g of initiator (V-50, azo initiator, Wako Pure Chemical Industries, Ltd.) dissolved in 10 g of ion-exchanged water are added, Hold for 15 minutes. Next, after heating to 75 ° C., 380 g of vinyl acetate and 0.8 g of initiator (V-50) dissolved in 160 g of ion-exchanged water were dropped from separate dropping funnels over 3 hours, and polymerization was performed. went. Next, the temperature was raised to 82 ° C., aged for 1 hour, cooled, and taken out. A cationic emulsion 1 having a solid content concentration of 36.3% and an average particle size of 5.68 μm was obtained.

<Manufacture of newspaper printing paper>
[Example 1]
Radiatapine Chemi-thermomechanical pulp (TMP, CSF 100ml, whiteness 45.0%, opacity 95.0%), Japanese red pine groundwood pulp (GP, CSF80ml, whiteness 64.0%, opacity 94.0%), deinked pulp (DIP, CSF 180ml, whiteness 54.0%, opacity 90.0%), softwood kraft pulp (NKP, CSF650ml, whiteness 83.0%, opacity 65.0%) into a mixed pulp slurry with a compounding ratio of 20/10/50/20, silica-based Add filler to 1% per pulp weight and paper quality improver EM-1 to 0.5% per pulp weight, using a twin wire paper machine with jet / wire ratio of 101% and paper speed of 500m / min. A newsprint paper with a basis weight of 40 g / m ² was produced. The linear pressure of the first press (hereinafter referred to as 1P) is 60 kgf / cm, 2P is 60 kgf / cm, and 3P is 70 kgf / cm. Hydroxyethylated starch was applied as a surface treatment agent to both surfaces at 0.20 g / m ^2, and the calendar was released (bypass).
Table 1 shows the paper quality results.
<Measurement of paper quality>
Density: Measured according to JIS P 8118.
-Stiffness: Using a pure bending property tester (manufactured by SMT Co., Ltd.), the stiffness in the MD direction was measured, and in order to avoid the influence of the paper thickness, the value obtained by the following calculation formula was used as the stiffness.
Stiffness = 10 ⁵ × Pure bending stiffness measurement value / (paper thickness) ³
Here, the unit of the measured value of pure bending stiffness is μN · m ² / m, and the unit of paper thickness is μm.
-Opacity: Measured according to JIS P 8138.
-Coefficient of dynamic friction: Measured according to JIS P 8147. The front and back surfaces of the manufactured newspaper printing paper were superimposed and measured in the MD direction.
・ Printing test was conducted on the newspaper printing paper manufactured with an offset printing machine to evaluate the paper running failure and the tension fluctuation when changing the paper. Evaluation was made into the stage of 1 (no problem), 2 (somewhat bad), and 3 (bad).

[Example 2]
The same procedure as in Example 1 was performed except that the amount of the paper quality improver EM-1 added was 2.5% by weight.
Table 1 shows the paper quality results.

[Example 3]
The same procedure as in Example 1 was performed except that the amount of the paper quality improver EM-1 added was 5.0% by weight.
Table 1 shows the paper quality results.

[Example 4]
The same procedure as in Example 1 was performed except that the amount of the paper quality improver EM-1 added was 10% by weight.
Table 1 shows the paper quality results.

[Comparative Example 1]
Radiatapine Chemi-thermomechanical pulp (TMP, CSF 100ml, whiteness 45.0%, opacity 95.0%), Japanese red pine groundwood pulp (GP, CSF80ml, whiteness 64.0%, opacity 94.0%), deinked pulp (DIP, CSF 180ml, whiteness 54.0%, opacity 90.0%), softwood kraft pulp (NKP, CSF650ml, whiteness 83.0%, opacity 65.0%) into a mixed pulp slurry with a compounding ratio of 20/10/50/20, silica-based Add the filler to 1% per pulp weight and add the paper quality improver KB115 (produced by Kao Corporation), which is an ester of polyhydric alcohol and saturated fatty acid, to 0.5% per pulp weight. Using this, newsprint paper with a jet / wire ratio of 101%, a paper making speed of 500 m / min and a basis weight of 40 g / m ² was produced. The linear pressure of the first press (hereinafter referred to as 1P) is 60 kgf / cm, 2P is 60 kgf / cm, and 3P is 70 kgf / cm. Hydroxyethylated starch was applied as a surface treatment agent to both surfaces at 0.20 g / m ^2, and the calendar was released (bypass).
Table 1 shows the paper quality results.

[Comparative Example 2]
The same procedure as in Comparative Example 1 was performed except that the paper quality improver KB115 (manufactured by Kao Corporation) was changed to 2.5 solid weight%.
The paper quality results are shown in Table 1.

[Comparative Example 3]
Radiatapine Chemi-thermomechanical pulp (TMP, CSF 100ml, whiteness 45.0%, opacity 95.0%), Japanese red pine groundwood pulp (GP, CSF80ml, whiteness 64.0%, opacity 94.0%), deinked pulp (DIP, CSF 180ml, whiteness 54.0%, opacity 90.0%), softwood kraft pulp (NKP, CSF650ml, whiteness 83.0%, opacity 65.0%) into a mixed pulp slurry with a compounding ratio of 20/10/50/20, silica-based Add 1% of filler to the weight of pulp and add PT-205, a saturated fatty acid amide based paper quality improver (manufactured by Japan PMC Co., Ltd.) to 0.5% of the weight of pulp, and use a twin wire paper machine. A newsprint paper having a basis weight of 40 g / m ² was produced at a jet / wire ratio of 101% and a paper making speed of 500 m / min. The linear pressure of the first press (hereinafter referred to as 1P) is 60 kgf / cm, 2P is 60 kgf / cm, and 3P is 70 kgf / cm. Hydroxyethylated starch was applied as a surface treatment agent to both surfaces at 0.20 g / m ^2, and the calendar was released (bypass).
Table 1 shows the paper quality results.

[Comparative Example 4]
The same procedure as in Comparative Example 3 was performed except that the paper quality improver PT-205 (manufactured by Japan PMC Co., Ltd.) was changed to 2.5 solid weight%.
The paper quality results are shown in Table 1.

[Comparative Example 5]
Radiatapine Chemi-thermomechanical pulp (TMP, CSF 100ml, whiteness 45.0%, opacity 95.0%), Japanese red pine groundwood pulp (GP, CSF80ml, whiteness 64.0%, opacity 94.0%), deinked pulp (DIP, CSF 180ml, whiteness 54.0%, opacity 90.0%), softwood kraft pulp (NKP, CSF650ml, whiteness 83.0%, opacity 65.0%) into a mixed pulp slurry with a compounding ratio of 20/10/50/20, silica-based Filler was added to 1% of pulp weight, and paper quality improver DU3605 (Nippon Yushi Co., Ltd.) was added to 0.5% of pulp weight. Using a twin wire paper machine, jet / wire ratio 101%, Newsprint paper with a basis weight of 40 g / m ² was produced at a papermaking speed of 500 m / min. The linear pressure of the first press (hereinafter referred to as 1P) is 60 kgf / cm, 2P is 60 kgf / cm, and 3P is 70 kgf / cm. Hydroxyethylated starch was applied as a surface treatment agent to both surfaces at 0.20 g / m ^2, and the calendar was released (bypass).
Table 1 shows the paper quality results.

[Comparative Example 6]
The same procedure as in Comparative Example 5 was performed except that the paper quality improver DU3605 (Nippon Yushi Co., Ltd.) was changed to 2.5 solid weight%.
The paper quality results are shown in Table 1.

[Comparative Example 7]
Radiatapine Chemi-thermomechanical pulp (TMP, CSF 100ml, whiteness 45.0%, opacity 95.0%), Japanese red pine groundwood pulp (GP, CSF80ml, whiteness 64.0%, opacity 94.0%), deinked pulp (DIP, CSF 180ml, whiteness 54.0%, opacity 90.0%), softwood kraft pulp (NKP, CSF650ml, whiteness 83.0%, opacity 65.0%) into a mixed pulp slurry with a compounding ratio of 20/10/50/20, silica-based Add 1% of filler to the weight of pulp and add a paper quality improver KB08W (manufactured by Kao Corporation), which is an adduct of alcohol alkylene oxide, to 0.5% of the weight of pulp. / Newspaper printing paper with a basis weight of 40 g / m ^{2 at} a wire ratio of 101% and a paper making speed of 500 m / min was produced. The linear pressure of the first press (hereinafter referred to as 1P) is 60 kgf / cm, 2P is 60 kgf / cm, and 3P is 70 kgf / cm. Hydroxyethylated starch was applied as a surface treatment agent to both surfaces at 0.20 g / m ^2, and the calendar was released (bypass).
Table 1 shows the paper quality results.

[Comparative Example 8]
The same procedure as in Comparative Example 6 was conducted, except that the paper quality improver KB08W (manufactured by Kao Corporation) was changed to 2.5 solid weight%.
The paper quality results are shown in Table 1.

[Comparative Example 9]
Radiatapine Chemi-thermomechanical pulp (TMP, CSF 100ml, whiteness 45.0%, opacity 95.0%), Japanese red pine groundwood pulp (GP, CSF80ml, whiteness 64.0%, opacity 94.0%), deinked pulp (DIP, CSF 180ml, whiteness 54.0%, opacity 90.0%), softwood kraft pulp (NKP, CSF650ml, whiteness 83.0%, opacity 65.0%) into a mixed pulp slurry with a compounding ratio of 20/10/50/20, silica-based Filler was added to 4% of the pulp weight, and a twin-wire paper machine was used to produce newsprint paper with a jet / wire ratio of 101%, a paper making speed of 500 m / min and a basis weight of 40 g / m ² . The linear pressure of the first press (hereinafter referred to as 1P) is 60 kgf / cm, 2P is 60 kgf / cm, and 3P is 70 kgf / cm. Hydroxyethylated starch was applied as a surface treatment agent to both surfaces at 0.20 g / m ^2, and the calendar was released (bypass).
Table 1 shows the paper quality results.

[Comparative Example 10]
Newsprint paper was obtained in the same manner as Comparative Example 1 except that no paper quality improver was added.
Table 1 shows the paper quality results.

  In the newspaper printing papers of Examples 1 to 4, the density of the paper is reduced as compared with Comparative Example 10 in which no paper quality improver is blended, but the decrease in stiffness is small, the opacity is high, and the dynamic friction coefficient is equal to or higher than that. Yes, the offset printing workability is also good. In the case of Comparative Examples 1 to 8 containing a conventional paper quality improver, there is an effect that the density of the paper is lowered and the opacity is improved. However, in Comparative Examples 1 and 2 in which an ester of a polyhydric alcohol and a saturated fatty acid is blended, the stiffness is lowered and the dynamic friction coefficient tends to be lowered. In Comparative Examples 3 and 4 in which a saturated fatty acid amide-based paper quality improver is blended, the stiffness is lowered and the dynamic friction coefficient tends to be lowered. In Comparative Examples 5 and 6, the stiffness is greatly reduced. In Comparative Examples 7 and 8 in which the alcohol alkylene oxide adduct is blended, the rigidity is lowered. In Comparative Example 9, the silica-based filler was increased, but the effect was only an improvement in opacity, and the paper density was not lowered.

Claims (5)

7 wt% aqueous solution viscosity at 50 ° C. is not more than 20 mPa · s or more and 5,000 mPa · s, as structural units of synthetic cationic polymers and vinyl acetate monomer content of nitrogen is less than 0.05 wt% to 1.0 wt% A paper stock containing 0.1 to 10 solids by weight based on the raw pulp, an internal additive paper quality improver comprising a polymer emulsion containing polymer particles having a glass transition point of -10 ° C or higher and 90 ° C or lower. paper was obtained by coating the surface treating agent on both sides, newsprint that dynamic friction coefficient of 0.3 0 to 0.60, the opacity is equal to or less than 90%.   2. The newsprint paper according to claim 1, wherein the content of mechanical pulp is 5 to 95% by weight.   The newspaper printing paper according to claim 1 or 2, wherein the ratio of the cationic polymer is 5 to 200 parts by weight with respect to 100 parts by weight of the polymer particles. The synthetic cationic polymer has at least one cationic polymer unit selected from the group consisting of (meth) acrylic acid-based, styrene-based, vinylpyridine-based, vinylimidazoline-based, and diallylamine-based polymerized units having a cationic group. The newspaper printing paper according to any one of claims 1 to 3 , wherein the newspaper printing paper is a polymer. The newsprint paper according to any one of claims 1 to 4, wherein the surface treating agent is hydroxyethylated starch.