JP5135012B2 - Newspaper and production method thereof - Google Patents

Description

  The present invention relates to newsprint and a method for manufacturing the same. More specifically, the present invention relates to newsprint suitable for offset rotary printing using cold set ink.

In order to reduce the burden of delivery work, reduce delivery costs, and effectively use resources, printing papers such as newspapers and free papers that are used daily in large quantities are desired to be lighter, especially in recent newspapers, Mainly used is lightweight newspaper with a basis weight of 36-50 g / m ² .

  However, as the weight reduction and effective use of resources increase the percentage of used waste paper, the blank newspaper opacity and printing opacity of the resulting newspaper will decrease. Therefore, as one measure for reducing the opacity, an inorganic filler is usually blended into the raw material pulp. The increase in the inorganic filler causes factors such as a decrease in the surface strength of newspaper and the generation of paper dust. It becomes.

  In recent years, with the increase in advertising media, there has been an increasing demand for the quality of the printed surface of newspaper. For this reason, for example, newspaper companies are increasing the speed of rotary presses and increasing the number of tower presses for double-sided color printing, and efforts are being made to improve the printing surface quality in multicolor printing with high-speed offset rotary printing. However, particularly in such multi-color printing (addition of a tower press for double-sided color) in high-speed offset rotary printing, there are problems such as a decrease in printability and a decrease in opacity of newspaper.

  Problems such as those described above cannot be addressed by conventional methods such as a technique for physically flattening the surface of the base paper or a means for applying a surface treatment agent to the surface of the base paper. This is because, for example, if the surface of a base paper containing a large amount of deinked waste paper pulp or mechanical pulp is subjected to a flattening treatment, the paper is once made, deinked by physical and chemical means, deteriorated, shortened, and becomes brittle. This is because the pulp fibers become paper dust and fall off from the surface of the newsprint, and also facilitate the fall off of the filler contained in the newsprint, leading to the fouling of printing facilities and poor printing.

  Therefore, as a technique for solving such a problem, for example, in Patent Document 1, a conventional calendar formed of a metal roll is replaced with a soft calendar including a combination of an elastic roll and a metal roll, and a metal roll (heat roll) is used. ) At 20 to 150 ° C., a method for producing newsprint paper for offset printing with a small amount of generated paper dust is described. However, the physical flattening process reduces the rigidity of the paper, worsens the handling as newsprint, makes it difficult for the reader to handle the newsprint, and makes the newsprint surface more precise, so It impedes absorption drying properties and causes problems of ink stains and set-off.

On the other hand, the technique of simply applying a surface treatment agent such as starch on the surface of the base paper requires a starch coating amount exceeding 2.0 g / m ² , for example. If a large amount of starch is applied in this way, wet water in offset printing is used. As a result, there is a problem that nepari occurs, and it becomes difficult for the newsprint to be peeled off from the blanket and the workability is lowered.

  Therefore, as a technique for solving such a problem, for example, Patent Document 2 discloses that a high-speed printing with a cold-set ink is performed by applying a newsprint coating composition containing a specific polymer latex to a newsprint base paper. In color offset rotary printing, newspapers are excellent in offset printing suitability such as surface strength, ink fillability, ink setability, etc. and tensile strength (especially wet tensile strength), and a good balance between these offset printing suitability and tensile strength. Techniques for obtaining a coating composition for paper and newsprint are disclosed. This is because latex generally has high film properties, so the strength of the newsprint surface is increased, and when printing is performed using cold-set ink, the ink is retained on the newsprint surface, so that the ink setting properties and ink setting properties are improved. Thus, it is intended to obtain offset printing aptitude.

However, such a polymer latex has too high film-forming property, and the ink setting property of the cold set ink in newspaper printing is warped and causes problems such as rubbing stains and ink back-off.
Japanese Patent Laid-Open No. 2002-285496 JP-A-6-123099

The main problem to be solved by the present invention is, for example, when the basis weight is as small as 36 to 50 g / m ² and is light, but it is used for multi-color offset high-speed rotary printing using cold set ink. Even if it is, rotary offset printing has good operability, high ink density and ink fillability, good ink setting, no color misregistration problem, excellent printability, and high printing opacity Is to provide a newspaper and a method of manufacturing the same.

The present invention as means for solving the above problems is as follows.
<Invention of Claim 1>
Newspaper paper in which calcium carbonate and hydrated silicic acid are added as a filler in raw pulp,
The calcium carbonate is agglomerated or crystallized in a chestnut shape having a BET specific surface area of 50 m ² / g or more and an oil absorption of 150 ml / 100 g or more,
The filler treating agent shown below is added in advance to 0.35 to 0.65 parts by mass with respect to 100 parts by mass of the calcium carbonate, and then added to the raw pulp and paper-made .
Newsprint water-soluble polymer on the front and back surfaces, characterized in that it is applied in a single-side coating amount of 0.2 to 2.0 g / m ² (solid content).
(Filler treatment agent)
A compound in which an alkyl group or alkenyl group and a hydrophilic group are bonded by at least one selected from the group consisting of an amide bond, an ester bond and an ether bond.

<Invention of Claim 2>
The water-soluble polymer compound is starch and / or polyvinyl alcohol;
The newsprint according to claim 1, wherein the paper surface has a pH of 6.0 to 8.8 .

<Invention of Claim 3 >
The newsprint according to claim 1 or 2 , wherein the hydrated silicic acid is not subjected to a drying step after reaction.

<Invention of Claim 4 >
In producing newsprint paper with calcium carbonate and hydrated silicic acid added as a filler in raw pulp,
Add a coagulant in the compound chest or between this and the machine chest,
Add flocculant in front of head box after machine chest,
A processing filler obtained by adding 0.35-0.65 parts by mass of the filler processing agent shown below to 100 parts by mass of calcium carbonate in advance is obtained, and this processing filler is added before the head box after the machine chest. and paper and,
A method for producing newsprint , comprising applying a water-soluble polymer compound to the front and back surfaces at a single-side coating amount (solid content) of 0.2 to 2.0 g / m ² .
(Filler treatment agent)
A compound in which an alkyl group or alkenyl group and a hydrophilic group are bonded by at least one selected from the group consisting of an amide bond, an ester bond and an ether bond.

<Invention of Claim 5 >
The newsprint paper manufacturing method according to claim 4 , wherein the calcium carbonate is diluted to 3.0 to 10.0% by mass, and the filler treatment agent is added to the diluted calcium carbonate slurry.

According to the present invention, even if the basis weight is as small as 36 to 50 g / m ² and it is lightweight, even when it is subjected to multicolor offset high-speed rotary printing using a cold set type ink, Newspaper paper with good printing operability, high ink density and ink fillability, good ink setting, excellent printability without color misregistration problems, and high printing opacity It becomes.

Next, an embodiment of the present invention will be described.
1) Filler treatment agent The filler treatment agent used in this embodiment has an alkyl group or an alkenyl group (hereinafter, this alkyl group or alkenyl group may be simply referred to as a hydrophobic group) and a hydrophilic group. It is a compound formed by bonding with at least one selected from the group consisting of an amide bond, an ester bond and an ether bond.

  The alkyl group or alkenyl group may have any of a linear structure, a branched structure, a cyclic structure, or various structures thereof. The alkyl group or alkenyl group has 4 or more carbon atoms, preferably 6 to 24 carbon atoms, to exhibit sufficient hydrophobicity. The alkyl group or alkenyl group may contain elements other than carbon and hydrogen, such as oxygen, nitrogen, and halogen, or a functional group made of these, as long as the hydrophobicity is not impaired. Examples of such an alkyl group or alkenyl group in this embodiment include normal hexyl, normal octyl, normal decyl, normal dodecyl, normal hexadecyl, normal octadecyl, normal octadecyl, and other normal alkyl groups, isohexadecyl, isooctadecyl and the like. Isoalkyl groups, cyclohexyl, nonylcycloalkyl, etc., which may be substituted by alkyl groups, alkenyl groups such as tetradecenyl, hexadecenyl, octadecenyl, etc., hydroxyalkyl groups such as hydroxyoctadecenyl, aminooctadecene An aminoalkyl group such as nyl, a fluoroalkyl group such as perfluoroalkyl, and the like.

  The hydrophilic group of the filler treating agent (compound) contains any one or two or more atoms such as carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur, and has a hydrophilic group, And / or having a hydrophilic structure including a polymer chain or the like. This hydrophilic group is a group that can be bonded to the hydrophobic group by at least one of an amide bond, an ester bond, and an ether bond.

  Examples of the compound that gives the hydrophilic group bonded to the hydrophobic group through the bonding group include oxyethylene, oxypropylene, ethylene glycol, propylene glycol, glycerin, ethyleneimine and their polymers, (meth) acrylamide, (Meth) allylamine, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, (meth) allylsulfonic acid, styrenesulfonic acid, vinylsulfonic acid, phosphoric acid of hydroxyalkyl (meth) acrylate A water-soluble polymer containing a salt of ester diallyldimethylammonium as a monomer component, and further containing a hydrophilic functional group capable of forming an amide bond, an ester bond or an ether bond as an essential structure by binding to the hydrophobic part, polyvinyl Amine, polyvinyl alcohol , Polyalkylene polyamines and water-soluble polymers thereof, such as quaternized, starch, cellulose, chitosan, natural water-soluble polymers alginic acid, and modified products thereof, water-soluble compounds consisting of, or the like.

  In the filler treating agent according to the present invention, a hydrophobic group and a hydrophilic group are bonded by at least one bonding group selected from the group consisting of an amide bond, an ester bond and an ether bond.

One of the suitable examples of the filler treating agent used in this embodiment is represented by the following general formula (1).
RA- (EO) _m (PO) _n- H (1)

  In General Formula (1), —A— represents —O— or —COO—, and R represents an alkyl group or alkenyl group having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms. In the formula, E represents an ethylene group, P represents a propylene group, m and n are average added mole numbers, and the sum of m and n is 1-60.

  The compound represented by the general formula (1) is, for example, an alcohol having 6 to 24 carbon atoms, preferably an alcohol having 10 to 22 or ethylene oxide in 1 mol of a fatty acid having 7 to 25 carbon atoms, preferably 11 to 23 carbon atoms, and It can be obtained by adding propylene oxide. The addition form of ethylene oxide and / or propylene oxide may be random or block, and is an alcohol having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms, or 1 mol of fatty acid having 7 to 25 carbon atoms, preferably 11 to 23 carbon atoms. 1 to 60 mol, preferably 2 to 40 mol. When it exceeds 60 mol, the filler dispersion effect as a filler treating agent is lowered, and the opacity may be lowered.

Another preferred example of the filler treating agent used in this embodiment is represented by the following general formula (2).
R1-A1- (EO) _m (PO) _n- CO-R2 (2)

  However, -A1- shows -O- or -COO- in General formula (2), R1 and R2 are C1-C24, Preferably it is a C10-C22 alkyl group or an alkenyl group, R1 and R2 may be the same or different, and at least one of R1 and R2 represents an alkyl group or alkenyl group having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms. In the formula, E represents an ethylene group, P represents a propylene group, m and n are average added mole numbers, and the sum of m and n is 1-60.

  The compound represented by the general formula (2) is, for example, an alcohol having 6 to 24 carbon atoms, preferably an alcohol having 10 to 22 carbon atoms, or ethylene oxide in 1 mol of a fatty acid having 7 to 25 carbon atoms, preferably 11 to 23 carbon atoms, and After adding propylene oxide, it can be obtained by esterification with 1 mol of a fatty acid having 2 to 25 carbon atoms. For example, after adding ethylene oxide and / or propylene oxide, it can also obtain by esterifying with 1 mol of fatty acids having 7 to 25 carbon atoms, preferably 11 to 23 carbon atoms. The addition form of ethylene oxide and / or propylene oxide may be random or block, and is added in a proportion of 1 to 60 mol, preferably 2 to 40 mol, per 1 mol of alcohol or fatty acid. When it exceeds 60 mol, the filler dispersion effect as a filler treating agent is lowered, and the opacity may be lowered.

Furthermore, the filler treating agent used in this embodiment contains a compound represented by the following general formula (3).
R1-O- (EO) _m (PO) _n- R2 (3)

  However, in general formula (3), R1 and R2 are alkyl groups or alkenyl groups having 1 to 24 carbon atoms, preferably 10 to 22, and R1 and R2 may be the same or different, At least one of R1 and R2 represents an alkyl group or alkenyl group having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms. In the formula, E represents an ethylene group, P represents a propylene group, m and n are average added mole numbers, and the sum of m and n is 1-60.

  The compound represented by the general formula (3) has, for example, 1 to 1 carbon alcohol having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms, and ethylene oxide and / or propylene oxide added thereto. It can be obtained by etherification with 24, preferably 10-22 alcohol or 1 mole of alkyl halide having 6-24 carbon atoms, preferably 10-22 carbon atoms. The addition form of ethylene oxide and / or propylene oxide may be random or block, and it is 6 to 24 carbon atoms, preferably 1 to 60 mol per 1 mol of alcohol having 10 to 22 carbon atoms or 7 to 25 carbon atoms, Preferably it is added in a proportion of 2 to 40 mol. When it exceeds 60 mol, the filler dispersion effect as a filler treating agent is lowered, and the opacity may be lowered.

  The alcohol having 6 to 24 carbon atoms may be any of linear alcohol, branched chain alcohol, saturated alcohol, and unsaturated alcohol. Among these various alcohols, alcohols having 10 to 22 carbon atoms are preferable, and lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, and oleyl alcohol are particularly preferable. These may be used alone or in combination of two or more.

  The fatty acid having 7 to 25 carbon atoms may be any of linear fatty acid, fatty acid having a branched chain, saturated fatty acid, and unsaturated fatty acid. Among these various fatty acids, fatty acids having 10 to 22 carbon atoms are preferable, and lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and oleic acid are particularly preferable. These may be used alone or in combination of two or more.

  In view of improving the paper thickness, at least one of R1 and R2 in the general formulas (2) and (3) is preferably an alkyl group or alkenyl group having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms.

  The filler treating agent may be obtained by reacting an amide compound obtained by reaction of monocarboxylic acid or a derivative thereof with polyalkylene polyamines and epihalohydrin. Examples of the monocarboxylic acid or a derivative thereof for obtaining the filler treating agent include fatty acids having 6 to 24 carbon atoms, esters of fatty acids having 6 to 24 carbon atoms, and acid anhydrides of fatty acids having 6 to 24 carbon atoms. it can. The fatty acid may be any of straight-chain fatty acids having 6 to 24 carbon atoms, fatty acids having a branched chain, saturated fatty acids, and unsaturated fatty acids. Among these various fatty acids, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and oleic acid are particularly preferable. These may be used alone or in combination of two or more. Examples of fatty acid esters include the lower alcohol esters of the above fatty acids. Examples of lower alcohol esters of fatty acids include fatty acid lower esters such as methyl esters of fatty acids, ethyl esters of fatty acids, and propyl esters of fatty acids. In addition, as a lower alkyl group in the lower alkyl ester of this fatty acid, an alkyl group having about 1 to 5 carbon atoms can be mentioned. The fatty acid ester in this embodiment can be obtained by a conventionally known esterification reaction between a fatty acid and an alcohol. These may be used alone or in combination of two or more. Examples of fatty acid acid anhydrides include the acid anhydrides of the above fatty acids. Examples of the acid anhydride of the fatty acid include the above-mentioned anhydrides of various fatty acids.

  Polyalkylene polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, dipropylenetriamine, tripropylenetetramine, hexamethylenediamine, iminobispropylamine and these. Examples include alkylene oxide adducts of amines, and these may be used alone or in combination of two or more. Among these, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine are preferable, and tetraethylenepentamine is particularly preferable. These may be used alone or in combination of two or more.

  The filler treatment agent in the present invention has good offset rotary printing operability, has high ink density and ink fillability, has good ink setability, and does not cause color misregistration, and has excellent printability. In order to bring about high printing opacity, it can be effectively improved by using it in combination with a filler with a relatively large specific surface area. Especially, it does not require chestnut-like calcium carbonate or drying treatment. Can be suitably used in combination with hydrated silicic acid having an aggregate structure.

2) Pulp The pulp constituting the newsprint base paper of the present invention preferably contains 30 to 100% by mass of deinked waste paper pulp based on the total pulp components. Such an increase in the amount of deinked wastepaper pulp contains a larger amount of fine inorganic substances (for example, filler) derived from wastepaper, and the content of deinked wastepaper pulp that has been reused many times increases. Even if there is, by treating the filler with the filler treating agent according to the present invention, the paper powder from the deinked wastepaper pulp deteriorated due to the strength reduction of the deinked wastepaper pulp, the fine inorganic substance derived from the wastepaper, or excessive recycling. While improving the problem, it is possible to improve the opacity and printing opacity, which are the problems of the present invention, and the printability.

  In the present invention, as will be described later, the filler to be blended with the deinked waste paper pulp preferably contains at least specific potato chestnut-like calcium carbonate and / or hydrated silicic acid that has not undergone a drying treatment, and is further pre-filled. Since the deinked waste paper pulp is contained in a large amount of 30 to 100% by mass based on the total pulp components, the newsprint according to the present invention contains the deinked waste paper pulp. The conventional problems when blended in a large amount are solved, the printing operability is good, the ink density is good, the ink setting is good, and the color misalignment problem does not occur. Excellent and high printing opacity is maintained.

  As the deinked waste paper pulp used in this embodiment, it tends to contain a lot of fine inorganic fine particles, and for example, disaggregation / deinking manufactured from magazine waste paper, newspaper waste paper, waste paper waste paper, leaflet waste paper, office waste paper, etc. -Bleached deinked waste paper pulp and the like can be mentioned, and one or more of these can be appropriately selected and used.

  Among these, used newspapers have a raw material pulp structure equivalent to that of newsprints, so that the present invention can be expressed effectively. Used newspapers can be recovered as the same varieties among other various types of used paper, and although the recovery rate of used paper is high and the quality is stable, the high recovery rate causes deterioration due to recycling, short fibers By applying the present invention, the web offset printing operability is good, the ink density is good and the ink setting property is good, and the problem of color misregistration does not occur. It is excellent in printability and can exhibit the most effect in producing high printing opacity.

  In this embodiment, the deinked waste paper pulp is contained in an amount of 30 to 100% by mass, preferably 50 to 100% by mass, and more preferably 70 to 100% by mass based on the total pulp components.

3) Paper surface pH
In order to obtain the newsprint of the present invention, a filler treated with a filler treatment agent is added to the pulp slurry made of the raw material pulp, for example, preferably a paper pH of 6.0 to 8.8, more preferably a paper surface. Adjusting conditions such as papermaking pH so that it is neutral to alkaline at pH 6.5 to 8.5, and adopts a method of making paper on a normal paper machine such as a long net paper machine or a twin wire type paper machine can do.

  If the paper surface pH is less than 6.0, the dissolution of calcium carbonate occurs and the filler treatment agent is detached from the calcium carbonate, and there is a problem that calcium hydroxide is generated. On the other hand, if the pH exceeds 8.8, the filler The effect of a processing agent will be inhibited, and the problem that the effect of a size agent, a coagulant | flocculant, and a coagulant | flocculant used together will also arise.

Even in hydrated silicic acid that has not been subjected to a drying treatment that can be suitably used in the present invention, when the paper surface pH is less than 6.0, a finely dispersed hydrated silicic acid obtained by not performing the drying treatment, The problem that aggregation is likely to occur as if subjected to a drying treatment is expressed, and when the pH exceeds 8.8, the effect of the filler treatment agent is hindered.
In particular, by adjusting the papermaking pH conditions so that the paper surface has a pH of 6.0 to 8.8, the problem of inhibiting the effect of the filler treatment agent can be avoided, and in high-speed rotary offset printing on newsprint, Although the dampening water applied to the paper varies depending on the newspaper company, it is almost neutral, so when it is used for multi-color offset high-speed rotary printing using cold set ink, the offset rotary printing operability is good. In addition, while having a high ink density and ink fillability, the ink setting property is good, the problem of color misregistration does not occur, the printability is excellent, and high printing opacity can be maintained. Furthermore, the paper is recycled as waste paper again, and can be effectively used as newsprint containing the filler treated with the filler treating agent according to the present invention.

  In this specification, the pH of the paper surface is visually determined with a color change standard meter using a reagent (MPC-BCP, -BTB, -CR, -TB) with a pH measurement kit for paper surface (manufactured by Kyoritsu Riken). This is the value measured.

4) Basis Weight The newsprint according to the present invention has a basis weight based on the “basis weight measuring method” described in JIS P 8124 of 36 g / m ² or more, preferably 37 g / m ² or more, and 50 g / m ² or less, preferably ones 46 g / m ² of the following weight.

In this embodiment, unlike a method of using a conventional flocculant or a yield improver to contain a filler in paper, a filler treatment agent is used to achieve uniform dispersion of the filler. By using a filler treating agent for corn-like calcium carbonate and / or hydrated silicic acid that has not undergone a drying treatment, the opacity and paper strength are insufficient in a lightweight newsprint with a basis weight of 46 g / m ² or less. In recent high-speed printing of up to 180,000 copies / hour, it is possible to improve the occurrence of a problem that paper breaks easily occur.

5) Filler In the newsprint according to the present invention, calcium carbonate and hydrated silicic acid are added as filler, and the calcium carbonate is 3.0 to 10.0%, preferably 5.0 to 8.0%. It is desirable to be diluted (slurry) and added to the raw material pulp in the state where the above-mentioned filler treatment agent is added. The reason why calcium carbonate is diluted in this way is that when the calcium carbonate slurry concentration exceeds 10.0%, the compatibility (dispersibility) of the filler and the filler treatment agent is poor, causing uneven effect of the filler treatment agent and aggregation of the filler. This is because problems arise.

If it is less than 3.0%, the concentration of the filler slurry treated with the filler treatment agent relative to the raw material pulp is dilute, so that the required addition amount is increased and the addition work is complicated, and the dilution of the filler treatment agent is also performed. This tends to reduce the effect of the filler treatment agent.
In addition, by adding a filler treatment agent to the calcium carbonate slurry, it becomes possible to efficiently perform the filler treatment on calcium carbonate having a complex shape such as chestnut that can be suitably used in the present invention. At the same time, aggregation of individual calcium carbonate particles and generation of aggregates are suppressed, and calcium carbonate can be uniformly contained in the paper to improve the printing opacity by 1.0 to 1.5%.

  In this embodiment, a desirable addition amount of the filler treating agent is 0.35 to 0.65 parts by mass, preferably 0.4 to 0.6, with respect to 100 parts by mass of calcium carbonate. If the added amount is less than 0.35 parts by mass, there is a problem that the effect of the filler treatment agent cannot be sufficiently exhibited. On the other hand, if the added amount exceeds 0.65 parts by mass, the effect reaches a peak, and the cost-effectiveness is reduced. There is a risk of problems causing contamination.

Calcium carbonate and hydrated silicic acid preferably used in this embodiment are not subjected to a drying step after reaction with calcium carbonate agglomerated or crystallized in a chestnut shape having a BET specific surface area of 50 m ² / g or more and an oil absorption of 150 ml / 100 g or more. Mention may be made of hydrated silicic acid.

  In this embodiment, chestnut-like calcium carbonate can be suitably used.

  Chestnut-like calcium carbonate reacts with calcium hydroxide and a carbon dioxide-containing gas, for example, in the process of obtaining calcium carbonate with a spindle-type or columnar stable calcite-type crystal structure or calcium carbonate with a metastable aragonite-type crystal structure. When the carbon dioxide-containing gas supply method is adjusted, or when dehydration, drying, and heat treatment are performed, for example, an additive such as condensed phosphoric acid or a metal salt thereof is added to agglomerate the spindle or columnar crystal structure. Obtained by crystallization.

In the case of calcite-based calcium carbonate, calcite is produced more naturally than limestone because it is more stable than other crystal structures. In addition, artificially, for example, natural limestone is decomposed into calcium oxide and carbon dioxide at high temperatures (impurities are removed), and calcium oxide is put into water to form calcium hydroxide (soaking). The calcite calcium carbonate can be obtained by blowing carbon dioxide while controlling the conditions (temperature, concentration, degree of stirring) as in the following reaction formula.
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O

Aragonite-based calcium carbonate is almost the same as the method for producing calcite-based calcium carbonate, and aragonite-based calcium carbonate can be obtained by adjusting the reaction conditions during the production. For example, as shown in the following reaction formula, using slaked lime and water in a causticization reaction tank, stirring and mixing with a stirrer equipped with a stirring blade to prepare lime milk, the sodium carbonate addition rate, addition time, and temperature conditions are appropriately set It is obtained by adjusting to cause a causticizing reaction.
Na ₂ CO ₃ + CaO + H ₂ O → CaCO ₃ + 2NaOH

毬 Kuri calcium carbonate used in the present invention has an oil absorption amount of 150 ml or more in accordance with “Pigment test method—Part 13: Oil absorption amount—Section 1: Refined oil oil method” described in JIS K5101-13-1. The BET specific surface area is preferably 50 m ² / g or more, preferably 50 to 150 m ² / g, and the volume average particle diameter is preferably 1.0 to 10.0 μm.

  If the amount of oil absorption of Hashikari calcium carbonate is less than 150 ml / 100 g, for example, there may be a decrease in opacity of white paper and an increase in bleeding in cold-set offset printing, while if it exceeds 150 ml / 100 g, The vehicle component may penetrate into the paper and make it difficult to obtain an excellent printing density. Therefore, the amount of oil absorption of Oguri calcium carbonate is preferably 150 ml / 100 g or more, more preferably 160 ml / 100 g or more, and preferably 250 ml / 100 g or less, more preferably 245 ml / 100 g or less.

In addition, if the BET specific surface area of Oguri calcium carbonate is less than 50 m ² / g, the voids in the aggregated structure decrease, so that the ink absorbability may be lowered. On the other hand, if it exceeds 150 m ² / g, the filler dispersion There is a risk that the dilution viscosity of the ink becomes high, the operability is lowered, and the printing density is lowered. Therefore, it is preferable that the BET specific surface area of Oguri calcium carbonate is 50 m ² / g or more, more preferably 60 m ² / g or more, and 150 m ² / g or less, more preferably 145 m ² / g or less.
In the present specification, the BET specific surface area of Oguri calcium carbonate means a value measured with a high-speed specific surface area / pore distribution measuring device (model number: Asap 2420, manufactured by Shimadzu Corporation).

Further, when the volume average particle size of the calcium chloride calcium carbonate is less than 1.0 μm, when added as a filler, it becomes easy to enter the gaps between the pulp fibers constituting the paper, and the paper structure possessed by the calcium chloride calcium carbonate. It is difficult to exert the effect of increasing the bulk of the paper, and as a result, the printability may be reduced. On the other hand, when the thickness exceeds 10.0 μm, the contact area with the pulp fiber is reduced. There is a possibility that powder may be generated and printability may be deteriorated. Therefore, the volume average particle diameter of the calcium chloride calcium carbonate is preferably 1.0 μm or more, more preferably 1.8 μm or more, more preferably 10.0 μm or less, and further preferably 9.6 μm or less.
In this specification, the volume average particle size of calcium chloride calcium carbonate is a particle size distribution measuring device for a dispersion solution in which 10 mg of a sample is added to 8 ml of a methanol solution and dispersed for 3 minutes by an ultrasonic disperser (output: 80 W). It means a value measured with a laser type microtrack particle size analyzer, manufactured by Nikkiso Co., Ltd.

  Further, the aspect ratio (the ratio of the major axis to the minor axis (major axis / minor axis)) of the calcium chestnut calcium carbonate is 3.5 or less, and further 3 from the viewpoint of further improving the opacity and printability of newspaper. .4 or less, and from the viewpoint of sufficiently suppressing deterioration in quality of newsprint, it is preferably 2.0 to 3.3.

  In the present invention, in order to sufficiently improve the printability, printing opacity, whiteness, etc. of the intended newsprint, the above-mentioned calcium carbonate is added to the filler in an amount of 5% by mass or more based on the total amount of the filler. It is preferably contained in an amount of 20% by mass or more, particularly 40% by mass or more.

  In this embodiment, hydrated silicic acid that does not undergo a drying treatment can be suitably used.

Hydrated silicic acid is present in the form of primary particles in the stable period after reaction, although the primary particles of hydrated silicic acid are small and the particle size is relatively uniform in the process where the reaction is completed in the production process. They are not agglomerated and form secondary particles. In addition, when a drying process is performed in the product production process, secondary particles may form aggregates, and coarse particles may be generated. The reason is not clear, but the hydrated silicic acid in the slurry state does not have some silica atoms and is liberated in the form of -SiOH, and the two-dimensional structure becomes a network tube and the surface is porous. Yes. On the other hand, the dried hydrated silicic acid has a basic structure of SiO ₂ tetrahedron and shares a three-dimensional network structure sharing oxygen. Therefore, when the hydrated silicic acid is once dried, the bonding force with the cellulose fibers due to -SiOH on the surface decreases, so that the hydrated silicic acid that has finished the reaction remains in a slurry state and is not subjected to a drying treatment. It is preferable to add to the raw material pulp as a filler after performing wet pulverization to subdivide the excessive secondary aggregates produced in the stable period.

  In this embodiment, by using a filler treating agent for the hydrated silicic acid that has not undergone the drying treatment, high speed papermaking such as a paper making speed of 1300 m / min or more is possible, and for example, 180,000 parts / hour, for example. It has been found that newsprint paper that is light in weight, does not generate paper dust, and has excellent opacity, in particular, printing opacity, while being compatible with high-speed offset rotary printing.

  Furthermore, in the present embodiment, the surface of the filler is preliminarily treated with a filler treatment agent by combining calcium carbonate aggregated or crystallized in the shape of the chestnut and hydrated silicic acid that does not undergo a drying step after the reaction. Even when it is subjected to color offset high-speed rotary printing, the offset rotary printing operability is good, the ink density is good and the ink setting property is good, and the problem of color misregistration does not occur. Newsprint paper that is excellent in printability and that maintains high printing opacity can be provided.

-Mixing ratio of calcium carbonate and hydrated silicic acid To improve printability, bulkiness and paper strength in a well-balanced manner, and to reduce costs, the ratio of chestnut-like calcium carbonate and hydrated silicic acid without drying treatment (Chestnut-like calcium carbonate: hydrated silicic acid (mass ratio)) is preferably 5:95 or more, more preferably 20:80 or more, and preferably 80:20 or less, and more preferably 60:40 or less.

  By combining calcium carbonate and hydrated silicic acid in a suitable manner, the web offset printing operability is good, the ink density is good, and the ink setting is good, resulting in color misregistration problems. Therefore, it is possible to provide a newsprint that is excellent in printability and that maintains high printing opacity and a method for producing the same.

  In the newsprint according to the present invention, calcium carbonate and hydrated silicic acid are added as fillers, and the calcium carbonate is diluted to 3.0 to 10.0%, preferably 5.0 to 8.0%. (Slurry) is added to the raw pulp in the state where the above-mentioned filler treatment agent is added, but depending on the concentration of the raw pulp slurry added, the raw pulp fiber may be used in the mixing with the raw pulp. Since excessive physical dispersion force is added to the filler aggregate, the raw material pulp concentration is preferably low, and the filler is preferably added in an environment in which the filler itself is easily dispersed. In the finished chest, the fan pump suction side in front of the seed box, most preferably the fan pump suction in front of the seed box, inline, with a pulp concentration of 0.5 to .0%, preferably, it is desirable to add at 1.5 to 3.0% concentration.

6) Coagulant / flocculant In the present invention, the base paper can contain a flocculant and a coagulant, and a coating layer mainly composed of a water-soluble polymer can be provided on the base paper to obtain newsprint paper. In this case, it is desirable to add a coagulant in the pulp preparation process and a flocculant in the preceding stage of the papermaking process.

  This example will be described with reference to FIG. 1 together with the processing steps with the filler treating agent. That is, the raw pulp is fed to the seed box 4 via the receiving chest 1, the blending chest 2, and the machine chest 3, passed through the cleaner 6 and the decurator cleaner 7 by the first fan pump 5, and further by the second fan pump 8. It is sent to the head box 9.

  With respect to the flow of this pulp slurry, calcium carbonate is transferred from the calcium carbonate receiving tank 10 to the calcium carbonate addition tank 11, the concentration is diluted in the calcium carbonate addition tank 11, and the filler treatment agent 20 is added to the diluted calcium carbonate slurry. Added. The calcium carbonate slurry to which the filler treatment agent 20 has been added and dispersed is sent to the head box 9 by the transfer force of the second fan pump 8.

  In this case, a coagulant is added in or between the compound chest 2 or the machine chest 3, and preferably the coagulant is added in the machine chest 3, so that the reaction is continuously performed in combination with the flocculant in the subsequent step. It is desirable to disperse the filler and fix it to the raw pulp. Further, the flocculant 22 is added before the head box 9 after the machine chest 3.

For example, the coagulant is extremely fine that is fixed to the walls and cracks of raw pulp fibers, fibrillated fine fibers such as fillers derived from waste paper, and the raw pulp mixing stage and raw pulp feeding stage. The fine filler floating colloidally in the raw pulp slurry can be coagulated, and further, it can be fixed to the raw pulp by the flocculant added in the subsequent process, Furthermore, in the present invention, calcium carbonate or hydrated silicic acid treated with a filler treating agent in advance is used, so that excessive aggregation can be suppressed and high dispersibility can be obtained. Even a fine filler like calcium has the effect of suppressing white water contamination and reducing the SS content, and can improve the filler yield in paper at the paper making stage. Good web offset printing operability, high ink density and ink fillability, good ink setting, no color misregistration problem, excellent printability, and high printing opacity Can contribute to obtaining newsprint.
About hydrated silicic acid, the hydrated silicic acid is diluted from the hydrated silicic acid receiving tank 30 to a predetermined concentration in the hydrated silicic acid addition tank 11 and then fed to obtain the same effect as the calcium carbonate exemplified above. be able to.

  As a coagulant preferably added in the pulp preparation step as described above, for example, polyacrylamide (PAM), polyvinylamine (PVAm), polydiallyldimethylammonium chloride (Polydadomac, PDADMAC), polyamine (PAm), polyethyleneimine ( Organic polymer coagulants such as PEI) and inorganic coagulants such as sulfuric acid band and polyaluminum chloride. Among these, it is preferable to use at least one of PAM, PDADMAC, PAm, and PEI.

  Thereafter, it is optimal to add the flocculant in the head stage before the paper making process, that is, in the head box before the paper making net. By adopting such an addition procedure, in the slurry solution state before the papermaking raw material is put on the papermaking net, the cohesive effect of the coagulant increases the adhesion between the pulp fiber, calcium carbonate and regenerated particle aggregates, and the papermaking netting. Then, due to the aggregating effect of the aggregating agent, the adhesion between the pulp fibers and the calcium chloride calcium carbonate and the regenerated particle aggregates becomes stronger. As a result, the yield of the chestnut calcium carbonate and the regenerated particle aggregate in the paper is further improved. And when such an addition procedure is taken, the effect that smooth paper-making work progresses also with the further improvement of the yield of the chestnut calcium carbonate and the regenerated particle aggregate.

  In the present invention, after adding a coagulant in the pulp preparation stage, it is preferable to add a flocculant before the paper making process following the pulp preparation stage.

  As the flocculant, a cationic flocculant is particularly suitable for an anionic pulp and filler. As such a cationic flocculant, for example, the average molecular weight is 8 million to 12 million, more preferably 8.5 million to 11 million, and the proportion of the cationic monomer is 5 to 100 mol%, further 10 to 100 mol%. Cationic water-soluble polymers or copolymers can be used. Typical examples of such cationic flocculants include PAM. If the average molecular weight of the cationic flocculant is less than 8 million, the effect using the cationic flocculant may not be sufficiently exhibited. On the other hand, if the average molecular weight is larger than 12 million, the desired effect can be hardly improved. However, there is a risk of high costs.

Conventionally, coagulants and flocculants have been used to improve the yield of fillers that contribute to improving opacity, but in the use of conventional coagulants and flocculants, aggregates of fillers are formed, It has been used in the concept of adhering aggregates to raw pulp fibers. In this embodiment, the raw material pulp, preferably deinked, remains finely dispersed in the filler treatment agent so as not to form aggregates as much as possible. Although it is contained in raw pulp containing 30% by mass or more of waste paper pulp and uniformly dispersed and fixed to the pulp fiber, for example, the basis weight is as small as 36 to 50 g / m ^2, and the cold set is light. Even when it is subjected to multicolor offset high-speed rotary printing using mold ink, the offset rotary printing operability is good, the ink setting property is good, and the ink setting property is good, while having high ink density and ink setting. This makes it possible to provide newsprint paper that does not cause misalignment, has excellent printability, and maintains high printing opacity.

7) Clear coating agent In this embodiment, it is preferable that, for example, a water-soluble polymer compound is applied to the front and back surfaces of newsprint on a solid content of 0.2 to 2.0 g / m ² . When the coating amount (solid content) of the water-soluble polymer compound is less than 0.2 g / m ^2, it is difficult to obtain the effect of the clear coating agent, and when it exceeds 2.0 g / m ² , it is caused by the clear coating agent such as Nepari. Problem arises, such as sticking of newsprint paper to the rotary press.

  As a result, for example, the vehicle of cold set type offset ink is quickly absorbed, and even if the amount of printing ink is increased by using a high-speed rotary press or using a tower press for double-sided color, sufficient absorption and drying properties are expressed, Excellent printing opacity, printability, etc. can be ensured.

The reason why a combination of calcium carbonate or hydrated silicic acid aggregated or crystallized in the form of chestnut used in this embodiment and a water-soluble polymer compound is preferable is that the chestnut-like calcium carbonate is rich in three-dimensional porosity and has a large BET It has a specific surface area and is excellent in film formability when an offset ink receiving agent is applied to the newspaper paper surface based on a synergistic effect with a water-soluble polymer compound such as starch and / or polyvinyl alcohol (PVA). It is mentioned. In particular, the chestnut-like calcium carbonate has a larger oil absorption than normal calcium carbonate, and a basis weight of 36-50 g / kg is obtained by quickly absorbing and drying the cold set type offset ink on the surface of newsprint paper and combining it with a water-soluble polymer compound. Even when m ² is lightweight, it exhibits a further excellent effect of improving printing opacity.

  Suitable water-soluble polymer compounds include, for example, starch and PVA, and these can be used alone or simultaneously.

8) Surface Treatment The newspaper of this embodiment can be subjected to a flattening process using calendar equipment such as a super calendar, gloss calendar, and soft calendar.

Since the newspaper of this embodiment thus obtained can disperse the filler uniformly in the newspaper, the X-ray acceleration voltage using an X-ray microanalyzer (model number: E-MAX, manufactured by Hitachi, Ltd.) is 8 kV. In the area analysis of the paper surface under the condition that the diffusion region is 1 μm, the predetermined region of the aggregate particles having a particle size of 20 μm or more in the detection region in the size of the silicon detection region analyzed as the hydrated silica aggregate particle The area ratio in the (predetermined area is a 1 cm ² analysis area obtained by combining elemental analysis mapping photographs of the paper surface photographed at 500 times) can be suppressed to 10% or less.

Conventionally, map analysis of existing inorganic substances has been performed from elemental analysis of the paper surface using an X-ray microanalyzer. In general elemental analysis using an X-ray microanalyzer, each element is comprehensively detected. Therefore, the X-ray acceleration voltage is set to 15 kV or more, and more preferably 20 kV or more. However, with such a high acceleration voltage, the diffusion region according to the following formula exceeds 1 μm, and even the presence of inorganic particles in the thickness direction of the paper is detected, so the analysis of only the paper surface (paper surface) is accurate. I can't do it.
ρR = 0.0276E ₀ ^1.67 A / Z ^8/9
(Where R is the X-ray diffusion region, ρ is the average density, E ₀ is the acceleration voltage, A is the average molecular weight of the analysis site, and Z is the average atomic number.)

  Therefore, in this embodiment, in view of the relationship between the X-ray acceleration voltage and the diffusion region, an X-ray microanalyzer is used to analyze the surface of the paper on the condition that the X-ray acceleration voltage is 8 kV and the diffusion region is 1 μm. The hydrated silicic acid aggregate particles and the silicon detection area to be analyzed are adjusted so that the area ratio in the predetermined area of the aggregate particles having a particle diameter of 20 μm or more in the detection area is 10% or less. In this way, the target newspaper is realized.

  Further, the newsprint of this embodiment preferably has a formation index of 10% or less, more preferably 5 to 10%, particularly 6 to 9.5% by a sheet formation tester. The newsprint of this embodiment requires a predetermined tensile strength because it is mainly printed on a rotary press. Therefore, in order to obtain a predetermined tensile strength in the longitudinal direction, it is preferable from experience that a formation unevenness having a formation index of about 5% occurs. On the other hand, when the formation index exceeds 10%, it is difficult to obtain a sufficient longitudinal tensile strength, and for example, in offset printing, particularly in color printing, uneven absorption of ink along the formation unevenness occurs, and printability, in particular, There is a risk of reducing the printing opacity.

  In addition, in this specification, the formation index of newsprint means a value measured by a sheet formation tester (manufactured by Toyo Seiki Seisakusho). The formation index is a value obtained by using a sheet formation tester which is a light transmission type ground total. The measuring principle of this measuring instrument is that the light transmitted through the base paper is decomposed into pixels by a CCD camera, and the standard deviation, which is the variation in absorbance of each pixel, is divided by the average absorbance. The larger the formation index, the worse the formation.

  In particular, in this embodiment, newsprint with the ash content of 4 to 15% by mass and the formation index of 10% or less can be made at a high speed of, for example, 1300 m / min or more, and for example 180,000 It is preferable from the standpoint of providing newsprint paper that is light in weight, does not generate paper dust, and has excellent opacity, in particular, printing opacity, while supporting high-speed offset rotary printing such as parts / hour.

  In this embodiment, for example, high speed papermaking is possible, for example, at a papermaking speed of 1300 m / min or more, and it is lightweight while corresponding to high-speed offset rotary printing such as 180,000 copies / hour, for example, and no paper dust is generated. The objective is to provide newsprint with excellent opacity, especially printing opacity. Needless to say, it satisfies the basic quality required for original newsprint, but Macbeth after printing newsprint. The ink density of the printed part measured with a densitometer is preferably 1.25 or more, more preferably 1.27 or more, and preferably 1.36 or less, more preferably 1.34 or less. If the ink density is less than 1.25, it may be difficult to obtain a desired ink density, for example, in printing on an actual rotary press in a newspaper company. Conversely, if it exceeds 1.36, the ink density is sufficient. This can result in reduced print opacity and set-off problems.

The ink concentration can be adjusted, for example, by appropriately adjusting the degree of saponification or polymerization of the water-soluble polymer compound such as starch or PVA and the amount of use thereof.
In addition, in this specification, the ink density | concentration of the printing site | part after printing means the value calculated | required in the following ink density | concentration tests.

(Ink density test)
Using an RI printing aptitude tester (model number: RI-2 type, manufactured by Ishikawajima Industrial Machinery Co., Ltd.), offset printing ink (trade name: Newsz Naturalis (black), large, between the metal roll and rubber roll. After applying Nippon Ink Chemical Co., Ltd., ink usage: 0.85 ml), printing was performed at a speed of 30 rpm (test piece: CD direction 50 mm, MD direction 100 mm), and a constant chamber state (described in JIS P 8111) (Paper, paperboard and pulp-standard conditions for humidity conditioning and testing)) for 24 hours. About this print sample, the ink density of 25 printing parts selected at random is measured with a Macbeth densitometer, and these average values are calculated.

  The paper surface pH of the newsprint is preferably 6.0 or more, more preferably 6.5 or more, and is preferably 10.0 or less, more preferably 9.5 or less. For example, in correspondence to high-speed offset rotary printing such as 180,000 copies / hour, since the dampening water applied to the paper surface before printing varies depending on the newspaper company, it is almost neutral, so compatibility with dampening water In view of the above, it is preferable to adjust to such a paper surface pH range in order to reduce the risk of printing failure.

  In addition, in this specification, the paper surface pH is measured with a reagent for pH measurement on paper (manufactured by Kyoritsu Riken) (MPC-BCP: pH 4.8 to 6.8, MPC-CR: pH 6.8 to 8. 8) is a value measured visually with a discoloration standard meter.

  Further, the whiteness of the newsprint is 55% or more, more preferably 55.5 to 58, as measured according to “Pulp—Diffusion Blue Light Reflectance (ISO Whiteness) Measurement Method” described in JIS P 8212. % Is preferred. When the whiteness is less than 55%, not only the white paper appearance before printing is degraded, but also the appearance of the printed matter after offset printing, particularly after color printing, may be degraded.

The blank paper opacity of the newsprint is 88% or more, and further 90 to 94%, as measured in accordance with “Paper and paperboard—Opacity test method (paper backing)” described in JIS P 8149. It is preferable. If the blank paper opacity is less than 88%, not only the appearance of the blank paper before printing is deteriorated but also the appearance of the printed matter after the offset printing may be lowered.
The printing opacity after printing on the newsprint of this embodiment is preferably 0.5% or more, more preferably 0.8 to 2.0% higher than the blank paper opacity.

Further, the newsprint of this embodiment has a density measured in accordance with “Test method of thickness and density” described in JIS P 8118 of about 0.63 to 0.90 g / cm ^3. The Beck smoothness measured in accordance with the described “paper and paperboard—smoothness test method using a Beck smoothness tester” is 41 to 65 seconds to further improve printability and print operability in high-speed offset rotary printing. This is preferable in that it can be improved.

(Preparation of hydrated silicic acid)
2500 L of sodium silicate aqueous solution adjusted to a concentration of 195 g / L in terms of silicon dioxide (silica), 4800 L of fresh water and 130 kg of anhydrous sodium sulfate were charged into a reaction tank having a volume of 10 m ³ .

  After the temperature of the solution in the reaction vessel was 50 ° C., 410 L of sulfuric acid (concentration: 20% by mass) corresponding to 32.5% by mass of the total amount of sulfuric acid necessary for neutralizing sodium silicate was stirred. Added continuously over 12 minutes. After the addition of sulfuric acid, the reaction solution was heated to 90 ° C. over 35 minutes with stirring, and then aged for 10 hours at 90 ° C.

  Next, the remaining 850 L of sulfuric acid (concentration: 20% by mass) was continuously added over 25 minutes. Further, aging was performed for 20 minutes while maintaining the temperature. Thereafter, sulfuric acid was continuously added to adjust the pH of the slurry to 5.2. The slurry with adjusted pH was filtered and washed, and then wet pulverization and classification were sequentially performed to obtain hydrated silicic acid (secondary aggregate).

  These hydrated silicic acids are adjusted by appropriately changing the concentration, molar ratio, reaction temperature, addition rate and amount of chemicals to be added while following the above-mentioned production means, and are shown in Table 1. The hydrated silicic acid of preparation numbers 1-17 was obtained. Preparation Nos. 14 to 17 are obtained by further performing a drying process with a spray-drying type dryer to obtain a hydrated silicic acid (secondary aggregate) subjected to the drying process.

  The obtained hydrated silicic acid composed of secondary aggregates was analyzed by the laser analysis method, and the ratio of hydrated silicate particles having a volume average particle diameter and a particle diameter of 1 to 30 μm (shown as the particle ratio in Table 1). Was measured. Moreover, the oil absorption amount of the obtained hydrated silicic acid was measured based on JISK5101-13-1. Furthermore, the obtained hydrated silicic acid was diluted with fresh water to prepare diluted water having the concentrations shown in Table 1. Table 1 shows each measurement result and concentration.

(Preparation of chestnut-like calcium carbonate)
The chestnut calcium carbonate according to the present invention is obtained by reacting calcium hydroxide with a carbon dioxide-containing gas, for example, calcium carbonate having a spindle-type or columnar stable calcite-type crystal structure, or calcium carbonate having a metastable aragonite-type crystal structure. In the process of obtaining a spindle-type or columnar crystal structure by adjusting the supply method of the carbon dioxide-containing gas or adding an additive such as condensed phosphoric acid or a metal salt thereof when performing dehydration, drying, or heat treatment Is obtained by agglomeration and crystallization.

In the case of calcite-based calcium carbonate, calcite is produced more naturally than limestone because it is more stable than other crystal structures. In addition, artificially, for example, natural limestone is decomposed into calcium oxide and carbon dioxide at high temperatures (impurities are removed), and calcium oxide is put into water to form calcium hydroxide (soaking). The calcite calcium carbonate can be obtained by blowing carbon dioxide while controlling the conditions (temperature, concentration, degree of stirring) as in the following reaction formula.
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O

Aragonite-based calcium carbonate is almost the same as the method for producing calcite-based calcium carbonate, and aragonite-based calcium carbonate can be obtained by adjusting the reaction conditions during the production. For example, as shown in the following reaction formula, using slaked lime and water in a causticization reaction tank, stirring and mixing with a stirrer equipped with a stirring blade to prepare lime milk, the sodium carbonate addition rate, addition time, and temperature conditions are appropriately set It is obtained by adjusting to cause a causticizing reaction.
Na ₂ CO ₃ + CaO + H ₂ O → CaCO ₃ + 2NaOH

The chestnut calcium carbonate used in the present invention has an oil absorption of 150 to 250 ml / 100 g, a BET specific surface area of 50 to 150 m ² / g, and a volume average particle diameter based on the method described in JIS K 5101-13-1. The (secondary particle diameter) is preferably 1.0 to 10.0 μm.

  If the amount of oil absorption of Hashikari calcium carbonate is less than 150 ml / 100 g, for example, there may be a decrease in white paper opacity and bleeding in cold-set offset printing, while if it exceeds 250 ml / 100 g, the vehicle in the printing ink The components may penetrate into the paper and make it difficult to obtain an excellent printing density. Therefore, the amount of oil absorption of Oguri calcium carbonate is preferably 150 ml / 100 g or more, more preferably 160 ml / 100 g or more, and preferably 250 ml / 100 g or less, more preferably 240 ml / 100 g or less.

In addition, if the BET specific surface area of Oguri calcium carbonate is less than 50 m ² / g, the voids in the aggregated structure decrease, so that the ink absorbability may be lowered. On the other hand, if it exceeds 150 m ² / g, the filler dispersion The dilution viscosity of the ink becomes high, so that the operability is lowered, for example, the drying property of the cold-set type offset ink taken in is lowered, and there is a possibility that rubbing stains and printing print-off occur. Therefore, it is preferable that the BET specific surface area of Oguri calcium carbonate is 50 m ² / g or more, more preferably 70 m ² / g or more, and 150 m ² / g or less, further 130 m ² / g or less. High speed papermaking at a speed of 1300 m / min or more is possible, and while supporting high-speed offset rotary printing such as 170 to 200,000 copies / hour, for example, it is lightweight, does not generate paper dust, and has an opacity. This is preferable in providing newsprint with excellent printing opacity.
In addition, in this specification, the BET specific surface area of Oguri calcium carbonate means the value measured with the fully automatic BET specific surface area measuring device (model number: Frosorb 2300, Shimadzu Corporation make).

  Further, the calcium chloride calcium carbonate has a primary particle of, for example, 100 nm or less, and when its volume average particle diameter (secondary particle diameter) is less than 1.0 μm, when added as a filler, It becomes easy to enter inside the gaps between the pulp fibers that make up, and the effect of increasing the paper structure that such calcium chloride calcium carbonate has is difficult to be exhibited, and as a result, the printability may be lowered. The amount decreases and it becomes difficult to hold the ink. If the ink penetrates into the base paper or in the extreme case, the ink may penetrate into the back surface, resulting in a decrease in print density or print back-through. On the other hand, when the volume average particle size (secondary particle size) of the calcium chloride calcium carbonate exceeds 10.0 μm, the contact area with the pulp fiber decreases, and as a result, paper dust is generated at the paper making stage and the printing stage. In addition to the possibility of a decrease in printability, there is a risk of causing paper dust and printing defects due to the drop of calcium chloride. Therefore, the volume average particle diameter of the calcium chloride calcium carbonate is preferably 1.0 μm or more, more preferably 1.8 μm or more, more preferably 10.0 μm or less, and further preferably 9.6 μm or less.

[Manufacture of newsprint]
Deinked waste paper pulp (disaggregation / deinked waste paper pulp) and mechanical pulp (TMP) are blended in the proportions shown in Table 2, and the fillers (variety A and variety B) shown in Table 2 are mixed in Table 2 per ton of pulp. And a coagulant (variety a and variety b) shown in Table 3 was added to obtain a pulp slurry. In the present invention, as described above, it is preferable to add a coagulant in the pulp preparation stage. For example, the pulp and filler, and if necessary, an internal sizing agent, a fixing agent, a yield improver, a cation Various paper-making aids such as an agent, a paper strength enhancer, and an antifoaming agent are mixed in a compounding chest to become a finished raw material. Therefore, it is preferable that a coagulant (variety a) is added between the blended chest and the machine chest, and more preferably, the coagulant (variety) is added to the blended chest in order to sufficiently exert the coagulant effect in the finished raw material. More preferably, b) is further added.

  Next, the flocculant shown in Table 3 was added to the obtained pulp slurry, and paper was produced at a paper making speed of 1300 m / min with a long net paper machine to produce a paper. The water-soluble polymer compound shown in Table 4 was coated on the front and back surfaces of this paper by the coating method and one-side coating amount shown in the same table (total amount of all water-soluble polymer compounds) to obtain newspaper paper. .

  In addition, the ratio (variety A: variety B (mass ratio)) of the filler shown in Table 2 is 10 samples randomly selected in a 500-fold image using ash obtained in accordance with JIS P 8251 as a sample. The ratio of silica and calcium in terms of oxide was measured, and the measurement results at these 10 locations were averaged. The measurement was performed using an X-ray microanalyzer (model number: E-MAX, manufactured by Hitachi, Ltd.) and an electron microscope (manufactured by Shimadzu Corporation) under the condition of an acceleration voltage of 8 kV.

  Further, the filler shown in Table 2, the coagulant and the flocculant shown in Table 3, and the water-soluble polymer compound shown in Table 4 are as follows.

(Filler)
Heavy: Comparative Example 1 Heavy calcium carbonate (Shiraishi Kogyo Co., Ltd., P-30)
Spindle type: Comparative Example 4 Spindle type calcium carbonate (Toyo Excel, manufactured by Toyo Denka Co., Ltd.)
In addition, dilution concentration (%) is a value of 3.0 to 10.0% in a solid sentence.

(Filler treatment agent)
Examples of commercially available filler treating agents that fall under the present invention include chemical names FM8170, FM8171 (acrylamide polymer), FM8173 (styrene acrylate polymer) manufactured by Seiko PMC. In the examples of the present invention, FM8173 ( Styrene acrylate polymer) was used.
In addition, the addition amount is an addition amount per 100 parts by mass of calcium carbonate.

(Coagulant)
PEI: Polyethyleneimine PVAm: Polyvinylamine PDADMAC: Polydiallyldimethylammonium chloride PAm: Polyamine

(Flocculant)
PAM: Polyacrylamide

(Water-soluble polymer compound)
Esterified starch: 1-octenyl succinate esterified starch

  Each physical property of the obtained newspaper was measured by the following method. These results are shown in Table 5. Further, commercially available newsprints A to C were used as Comparative Examples 5 to 7, and each physical property was measured in the same manner. These results are also shown in Table 5. In addition, the kind of filler currently mix | blended with these commercially available newsprints AC is as showing below.

(Type of filler)
Newspaper A: Hydrated Silicic Acid Newspaper B: Spindle Type Calcium Carbonate Newspaper C: Hydrated Silicic Acid Further, methods for measuring physical properties are as follows.

(A) Basis weight It measured based on JISP8124.
(B) Paper surface pH
Using a pH measurement kit for paper (manufactured by Kyoritsu Riken), reagents (MPC-BCP, -BTB, -CR, -TB) were used and visually measured with a discoloration standard meter.
(C) Ash content It measured based on JISP8251.
(D) Formation index Measured with a sheet formation tester (manufactured by Toyo Seiki Seisakusho).
(E) Whiteness Measured according to JIS P 8212.
(F) Blank paper opacity Measured according to JIS P 8149.

(G) Printing Opacity Offset rotary printing press (model: RI-2, manufactured by Ishikawajima Industrial Machinery Co., Ltd.), offset rotary printing ink (trade name: News Zet Naturalis (black), Dainippon Ink and Chemicals, Inc. The ratio of the back-surface reflectance after printing to the back-surface reflectance before printing when the printing amount is 180,000 parts / hour and the printed surface reflectance is 9%.
(Back side reflectance after printing / Back side reflectance before printing) × 100 (%)
Asked. A spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd.) was used for measuring the reflectance.

(H) Opacity difference The difference (absolute value) between blank paper opacity and printing opacity was determined.

(I) Ink Concentration Using an RI printing aptitude tester (model number: RI-2 type, manufactured by Ishikawajima Industrial Machinery Co., Ltd.), offset printing ink (trade name: News Zet Naturalis) in the gap between the metal roll and the rubber roll. (Black), Dainippon Ink & Chemicals, Inc., ink usage: 0.85 ml), and printing at a speed of 30 rpm (test piece: CD direction 50 mm, MD direction 100 mm) (According to JIS P 8111) for 24 hours. About this print sample, the ink density | concentration of 25 printing parts selected at random was measured with the Macbeth densitometer, and these average values were calculated | required. If the ink density is less than 1.25, there may be a problem that the desired ink density does not occur, for example, in web offset printing in a newspaper company. Conversely, if it exceeds 1.36, the ink density is sufficient. However, there may be a decrease in printing opacity and a problem of set-off.

(J) Area ratio Using an X-ray microanalyzer (model number: E-MAX, manufactured by Hitachi, Ltd.) and an electron microscope (manufactured by Shimadzu Corporation), the X-ray acceleration voltage is 8 kV, and the diffusion region is 1 μm. The surface area of the paper surface was analyzed under the conditions, and the area ratio in the predetermined area of the aggregate particles having a particle diameter of 20 μm or more in the size of the silicon detection area (combined with the elemental analysis mapping photograph of the paper surface taken at 500 times) The area ratio in the analysis area of 1 cm ² was determined.

  Next, each characteristic was investigated about the newsprint of Examples 1-13 and Comparative Examples 1-7 based on the following test examples 1-5. The results are shown in Table 6.

Test Example 1 (Ink setting property)
Using an RI printing aptitude tester (model number: RI-2 type, manufactured by Ishikawajima Industrial Machinery Co., Ltd.), newspaper ink (trade name: Newsjet Naturalis (black), manufactured by Dainippon Ink & Chemicals, Inc.) After solid printing with, the coated paper was stacked on the printing surface and pressure-bonded at a constant pressure. The state of ink transfer to the coated paper was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
(Double-circle): The stain | pollution | contamination does not arise at all on the coated paper surface.
○: Slight dirt is generated on a part of the coated paper surface, but there is no practical problem.
Δ: Stain is observed on the entire coated paper surface.
X: Stain on the entire coated paper surface is remarkable.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test example 2 (ink inking property)
Using an offset printing machine (model number: Komori SYSTEMC-20, manufactured by Komori Corporation), using newspaper ink (trade name: Newsz Naturalis (black), manufactured by Dainippon Ink & Chemicals, Inc.), 18 Continuous 10,000 copies were printed at a speed of 10,000 copies / hour. About the obtained printed matter, the clearness and the shading unevenness of an image were observed visually, and it evaluated based on the following evaluation criteria.
(Evaluation criteria)
(Double-circle): The image is clear, there is no unevenness in density, and the ink deposition property is excellent.
A: The image is clear, there is almost no unevenness in density, and the ink deposition property is good.
Δ: There are portions where the image is unclear and unevenness in density, and ink inking properties are not good.
X: Overall, the image is unclear, the density unevenness is remarkable, and the ink deposition property is inferior.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test example 3 (surface strength)
Ink tack 18 using a color change tester (model number: RI-1 type, manufactured by Ishikawajima Sangyo Co., Ltd.) in accordance with “lithographic ink—Part 1: test method” described in JIS K5701-1. The printing was performed under the conditions of the first printing. The newspaper paper surface was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: The entire surface of the newsprint is not removed.
○: Slightly removed on a part of the newspaper surface, but there is no practical problem.
Δ: Taken over the entire newspaper surface.
X: Significant removal on the entire newspaper surface.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test Example 4 (Ink absorption unevenness)
Using an offset printing machine (model number: Komori SYSTEMC-20, manufactured by Komori Corporation), using newspaper ink (trade name: Newsz Naturalis (black), manufactured by Dainippon Ink & Chemicals, Inc.), 18 Printing was performed at a speed of 10,000 copies / hour. The obtained printed matter was visually observed for ink density unevenness and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: There is no unevenness in the ink density, and the image is uniform and clear.
◯: There is almost no ink density unevenness and the image is uniform.
(Triangle | delta): The ink density nonuniformity is recognized in part, and there exists a location where an image is unclear.
X: Overall, the ink density unevenness is remarkable and the image is unclear.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

Test Example 5 (printing operability)
(1) Cutter tip clogging Using an offset rotary printing press (model number: LITHOPIA BTO-N4, manufactured by Mitsubishi Heavy Industries, Ltd.), printing was performed at a rate of 180,000 copies / hour on 50-roll newspapers. The presence or absence of clogging of the sword tip was examined and evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: No sword clogging occurred.
○: A sword clog occurred only once with one winding.
Δ: Claw tip clogging occurred 2 to 3 times with one winding.
X: Sword tip clogging occurred 4 times or more with one winding.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

(2) Blanket paper dust piling Using an offset printer (model number: Komori SYSTEMC-20, manufactured by Komori Corporation), continuous 4-color printing of 5000 parts was performed at a speed of 180,000 parts / hour. The presence or absence of paper dust generation / deposition in the blanket non-image area was visually observed and evaluated based on the following evaluation criteria.
(Evaluation criteria)
(Double-circle): Generation | occurrence | production of paper dust is not recognized at all.
○: Slight generation of paper dust is observed, but no deposition on the blanket is observed.
(Triangle | delta): Generation | occurrence | production of paper dust is recognized and it has accumulated on the blanket.
X: Accumulation of paper dust on the blanket is remarkable.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

(3) Neppari (Blanket adhesive)
Two samples obtained by cutting newspaper paper into a size of about 4 cm in width and about 6 cm in length were prepared and immersed in water for 10 seconds, and then these two samples were quickly brought into close contact with each other. This was passed through a calendar at a linear pressure of 100 kg / cm, dried at room temperature for 24 hours, and then manually peeled off two samples (T peel peel test imitation sensory test). Based on the evaluation.
(Evaluation criteria)
(Double-circle): It did not peel and it did not adhere | attach at all.
○: Although partly adhered, it could be easily peeled off.
(Triangle | delta): There existed a part which has adhere | attached and was hard to peel.
X: Adhered as a whole, and fluffing of fibers from the adhesion surface was observed at the time of peeling.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

  The present invention can be applied as newsprint suitable for offset rotary printing using cold set ink.

It is explanatory drawing of the flow of a pulp and an additive.

DESCRIPTION OF SYMBOLS 1 ... Receiving chest, 2 ... Compounding chest, 3 ... Machine chest, 4 ... Seed box, 5 ... First fan pump, 8 ... Second fan pump, 9 ... Head box, 10 ... Calcium carbonate receiving tank, 11 ... Calcium carbonate Addition tank, 20 ... filler treatment agent, 21 ... coagulant, 22 ... flocculant, 30 ... hydrated silicate reception tank, 31 ... hydrated silicate addition tank.

Claims (5)

Newspaper paper in which calcium carbonate and hydrated silicic acid are added as a filler in raw pulp,
The calcium carbonate is agglomerated or crystallized in a chestnut shape having a BET specific surface area of 50 m ² / g or more and an oil absorption of 150 ml / 100 g or more,
The filler treating agent shown below is added in advance to 0.35 to 0.65 parts by mass with respect to 100 parts by mass of the calcium carbonate, and then added to the raw pulp and paper-made .
Newsprint water-soluble polymer on the front and back surfaces, characterized in that it is applied in a single-side coating amount of 0.2 to 2.0 g / m ² (solid content).
(Filler treatment agent)
A compound in which an alkyl group or alkenyl group and a hydrophilic group are bonded by at least one selected from the group consisting of an amide bond, an ester bond and an ether bond. The water-soluble polymer compound is starch and / or polyvinyl alcohol;
The newsprint according to claim 1, wherein the paper surface has a pH of 6.0 to 8.8 . The newsprint according to claim 1 or 2 , wherein the hydrated silicic acid is not subjected to a drying step after reaction. In producing newsprint paper with calcium carbonate and hydrated silicic acid added as a filler in raw pulp,
Add a coagulant in the compound chest or between this and the machine chest,
Add flocculant in front of head box after machine chest,
A processing filler obtained by adding 0.35-0.65 parts by mass of the filler processing agent shown below to 100 parts by mass of calcium carbonate in advance is obtained, and this processing filler is added before the head box after the machine chest. and paper and,
A method for producing newsprint , comprising applying a water-soluble polymer compound to the front and back surfaces at a single-side coating amount (solid content) of 0.2 to 2.0 g / m ² .
(Filler treatment agent)
A compound in which an alkyl group or alkenyl group and a hydrophilic group are bonded by at least one selected from the group consisting of an amide bond, an ester bond and an ether bond. The newsprint paper manufacturing method according to claim 4 , wherein the calcium carbonate is diluted to 3.0 to 10.0% by mass, and the filler treatment agent is added to the diluted calcium carbonate slurry.

Images