JP2010236153A - Method for producing printing paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for obtaining printing paper with high interlaminar strength by ameliorating the yield of fine components in paper stock on wires, i.e. a method for producing coated paper for printing by neutral papermaking technique at a papermaking speed of not less than 1,300 m/min. <P>SOLUTION: The printing paper with high interlaminar strength can be obtained, by improving the yield in high-speed papermaking process, by combined use of (a) a mixture of a filler and a copolymer 40 moL% or greater in quaternarization rate obtained by polymerization of a monomer component including a hydrophobic monomer and a cationic monomer and (b) an emulsion-type cationic polyacrylamide with a weight-average molecular weight of 10,000,000 or higher as determined by intrinsic viscosity method. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing paper manufacturing method. The present invention also relates to a method for preparing a paper stock for manufacturing printing paper. In particular, the present invention relates to a method for producing printing paper at high speed by a neutral paper making method using a gap former type paper machine equipped with an on-machine coater.

  In recent years, the development and improvement of paper machines have progressed, and in particular, the tendency of speeding up and widening of paper machines is remarkable due to high productivity. Further, as a papermaking coating machine (coater), on-machine coaters capable of consistently performing papermaking and coating have become widespread in recent years.

  With regard to the wire part of the paper machine, from the viewpoint of improving its dewatering capacity, it has shifted from a long net former to an on-top twin wire former and further to a gap former. In the gap former type paper machine, since the raw material jet ejected from the head box is immediately sandwiched between two wires, the surface of the raw material jet is less disturbed and the surface property is good. In addition, the gap former type paper machine is capable of dewatering from both sides of the paper layer and easily adjusting the amount of dewatering, making it possible to produce paper at a higher speed than the long net type and on-top type formers. There is an advantage that the difference between the front and back is small. On the other hand, in the gap former type paper machine, since the stock concentration is very thin, it is dehydrated rapidly from both sides of the paper layer, so the distribution of fine fibers and filler in the paper layer is localized to the surface layer, and the paper There is a tendency for the amount of fine fibers in the middle layer to decrease. For this reason, the gap former type paper machine has a problem that the interlayer strength is lowered, and further, the yield of the stock and ash on the wire in the paper making process is low. Therefore, in the coated paper for printing using the coated base paper manufactured by the gap former type paper machine, the interlayer strength is small, so that the moisture contained in the coated paper during heat drying after offset printing is low. Even if it evaporates, moisture cannot pass through the coating layer, causing separation between the paper layers, resulting in blistering, which is a phenomenon that the coating layer swells, resulting in serious quality problems such as rough printing. May occur. For this reason, the gap former type paper machine has been limited to the production of newsprint.

  In order to improve the blister of the coated paper for printing, it is necessary to increase the interlayer strength of the coated base paper to be used. Generally, in order to improve the interlayer strength, a method of adding a paper strength enhancer such as cationized starch or polyacrylamide is used in the paper making process. However, even if a paper strength enhancer is added to the stock, the strength of the paper strength enhancer is high in fixing to fine fibers. There are problems such as increased drainage and impaired formation. In particular, expensive polyacrylamide increases the cost, and the cohesiveness is strong, so the formation is deteriorated and the printing quality is lowered. In addition, cationized starch requires a large amount of addition compared to polyacrylamide, which may deteriorate the drainage and cause problems such as poor dehydration, increased drying load, and reduced wet paper strength. is there.

  In addition to the addition of the internal paper strength enhancer, a method for improving the interlayer strength by applying a paper strength enhancer for external addition has also been proposed (Patent Document 1). However, as described above, in the state where fine fibers are localized on the surface of the paper as in paper made with a gap former type paper machine, the paper strength enhancer does not penetrate into the base paper, and a sufficient effect is obtained. Absent.

  In recent years, various improvements have been made in terms of hardware in order to solve this problem. Conventionally, during the initial dehydration process, the dehydration was performed rapidly by equipment such as forming shoes, forming boards, and suction boxes, so the localization of fine fibers and ash on the surface of the paper was prominent. In the former type gap former type paper machine, the initial dehydration by the forming roll with suction and the dehydration blade can be used immediately after the dehydration blade. By imparting microturbulence to the paper layer to promote fiber dispersion, the distribution of fine fibers and fillers in the paper layer can be made uniform, and a good texture is obtained. Therefore, there is no extremely weak portion in the paper layer, and the paper strength enhancer added to the paper stock can effectively improve the paper strength, so that the interlayer strength is improved.

  However, the roll-and-blade former type gap-former type paper machine has improved the paper layer structure by allowing the initial dewatering to be moderated. Since the fine fibers and filler inside the paper come out, no significant improvement has been made with respect to the decrease in the yield of paper, which is a conventional problem of the gap former type paper machine.

  For this reason, as a technique for improving the yield, it is preferable to add anionic polymers such as bentonite and colloidal silica after addition of cationic polyacrylamide as a retention agent, and further add an anionic polymer. A prescription such as obtaining a high yield of fine fibers while maintaining the formation has been proposed (Patent Document 2). However, in the situation where speeding up, high ash differentiation, and high DIP blending are progressing, the current situation is that sufficient improvement has not been made in terms of interlayer strength, yield, and formation.

  By the way, as a coater, in recent years, an on-machine coater that continuously performs papermaking and coating has become widespread. The on-machine coater has the advantage of less capital investment and a smaller installation space than the off-machine coater, and can reduce the production cost because the base paper can be applied quickly. However, since papermaking and coating are performed continuously, if a paper break occurs, the production efficiency decreases greatly, for example, the paper passing time becomes longer. In particular, when coating is performed with an on-machine coater having a film transfer coater such as a metering size press coater or a gate roll coater, and then further coating is performed with an on-machine blade coater, paper breaks due to foreign matter on the surface of the base paper It is likely to occur. For this reason, in order to operate the blade coater efficiently, it is necessary to reduce the number of foreign matters in the raw material as much as possible, and the blending of pulp containing a large amount of foreign matters such as deinked pulp has been limited. Further, since it is necessary to increase the strength of the paper as a method for reducing the number of paper breaks, the use of the gap former type paper machine which is difficult to obtain the strength as described above has been limited.

  As the causative substance of the foreign matter, in particular, white pitch derived from the coating layer contained in the raw material from which the broken paper (coat broke) generated during coating is disaggregated, adhesive foreign matter derived from deinked pulp, natural pitch derived from mechanical pulp Is mentioned. As a countermeasure against such a foreign matter, it is known that a cationic polymer called a coagulant is added to the coating broke raw material, deinked pulp, and mechanical pulp before blending in the preparation step (Patent Documents 3 to 9). In general, the coagulant neutralizes the surface charge of anionic colloidal particles such as white pitch, adhesive foreign matter, and natural pitch, and soft flocs that gently fix the anionic colloidal particles to the fiber in the smallest possible state. It is thought to reduce the foreign matter trouble by forming.

  Various reports have been made on the method of adding a coagulant. For example, a method of adding a coagulant to waste paper pulp before being fed to the raw material preparation process of the paper machine (Patent Document 10), and a coagulant before being fed from the waste paper recycling process to the blending chest. A method of adding (Patent Documents 11 and 12), a method of adding a coagulant to a plurality of stocks in a preparation step before supplying to a seed box (Patent Document 13), For example, a method of adding a cationic water-soluble polymer to a raw material (Patent Document 14). In addition, after adding a cationic water-soluble polymer to each of at least one papermaking raw material before blending, a cationic polymer retention agent is added to the blended raw material mixed with the other papermaking raw materials including the papermaking raw material. The method (patent document 15), the method (patent document 16), etc. which add a cationic polymer in the disaggregation process after adding another pulp to the mixture of recovered clarified water and coating waste paper are reported.

  However, since the coagulant forms a soft floc that loosely bonds with the fibers as described above, the effect of the coagulant added to the raw material gradually decreases as it goes through the process, especially in high-speed paper machines with strong shearing force. However, there is a problem that fixed colloidal particles are desorbed. For this reason, an excessive amount of a coagulant is added to neutralize the charge of the colloidal particles again, and an increase in the amount of a retention agent added to re-fix the desorbed particles. However, there were problems such as generation of secondary deposits due to foreign particles coarsened halfway and an excessive amount of cationic chemicals. In general, it is known that when a cationic chemical having a large molecular weight is added to coarse particles, the coarse particles are fixed on paper, resulting in an increase in paper defects and paper breaks.

  Moreover, the method of adding the mixture of a cationic polymer and a cationic monomer with respect to the papermaking raw material composition containing a some pulp is known (patent document 17). However, in this method, since the coagulant is added after the coarsening of the colloidal substance due to contact with other pulp or chemicals or the destabilization of the foreign matter has occurred, it tends to cause troubles such as paper foreign matter, On the contrary, it may lead to paper breaks.

  Furthermore, a method of adding at least one of a polyvalent metal salt and a cationic polymer in at least two locations when adding a cationic yield / drainage improver in a papermaking system has been reported (Patent Document). 18). However, in this method, since the cationic polymer is added to the stock after mixing the raw materials for the purpose of improving the yield, coarsening of the colloidal substance or the like is actively promoted. For this reason, it is not possible to suppress problems related to operability such as the generation of deposits derived from coat broke, deinked pulp, and mechanical pulp as described above, and paper breakage, and conversely, these problems may be induced.

  Furthermore, a method of adding a coagulant to the preparation process of the papermaking raw material containing a plurality of pulps and the supply process from the seed box to the wire part has been reported (Patent Document 19). In this method, a coagulant is added before the screen downstream of the secondary pump in which a large amount of white water from the seed box is mixed and the solid content is generally less than 1.5%. Is added. However, even with this method, it is not possible to suppress the problems related to operability such as the generation of deposits and paper breaks derived from coat broke, deinked pulp, and mechanical pulp as described above, and conversely induce these problems. There is a case.

  In this way, with the conventional technology, it is not possible to avoid problems such as deposits due to coarsening of colloidal substances and foreign matters, particularly with respect to papermaking with a high-speed paper machine, and sufficiently overcome the decline in productivity. I couldn't. Further, in order to fix these foreign matters to the fibers, it is necessary to add an excessive retention agent. As a result, the paper quality is deteriorated such that the formation and the distribution of the filler become uneven. In particular, when manufacturing coated paper using a coater on-line continuously from coated base paper manufactured by a high-speed paper machine such as a gap former type paper machine, avoid operational problems such as paper breaks. In some cases, the productivity is lowered and the paper quality is lowered.

  With respect to the on-machine coater, when the amount of liquid absorbed by the size press increases, drying addition with a dryer takes place, and the paper making speed cannot be increased, and paper breakage may occur. Then, the technique using a neutral rosin (patent document 20) and an alkyl ketene dimer type | system | group (henceforth AKD) (patent documents 21-31) sizing agent is utilized. Moreover, the technique using alkenyl succinic anhydride (henceforth ASA), a styrene acryl type | system | group, etc. is also known as another internally added sizing agent (patent documents 32-35). However, AKD has a problem in that the amount of liquid absorption in a size press cannot be suppressed because the rise in size is slow. As for ASA, dirt in the system is likely to occur, and there is a problem that defects and paper breaks occur frequently. Neutral rosin was poor in size in high ash paper, and styrene acrylic was inferior in size compared to AKD and ASA. Further, an additive for papermaking, which is a mixture of a copolymer and a filler having a quaternization ratio of 40 mol% or more obtained by polymerizing a monomer component containing a hydrophobic monomer and a cationic monomer as an internal additive sizing agent, is added. Although the technology has been reported (Patent Document 36), under the papermaking conditions where the yield is low as in the gap former type paper machine, the yield of the papermaking additive is low, and it is difficult to express sufficient size. there were.

See JP-A-10-280296 WO2001 / 34910 JP 2005-206978 A JP 2005-179831 A JP 2005-133238 A Japanese Patent Laid-Open No. 2004-60084 JP 2001-262487 A Japanese Patent No. 3681655 JP 2005-2523 A JP 2005-206978 A JP 2005-179831 A JP 2005-133238 A Japanese Patent Laid-Open No. 2004-60084 JP 2001-262487 A Japanese Patent No. 3681655 JP 2005-2523 A JP 2003-183955 A JP 2000-282390 A JP 2006-138044 A JP 2008-231602 A JP 2008-274464 A JP 2007-177378 A JP 2006-193842 A JP 2006-138045 A JP 2006-132012 A JP 2006-132013 A JP 2006-132018 A JP 2006-118076 A JP 2006-118077 A JP 2006-118078 A JP 2006-118079 A JP 2008-255503 A JP 2000-303382 A JP 2008-274524 A JP 2009-35831 A WO 2008/90787

  In view of such circumstances, the present invention uses a roll-and-blade former type gap former type paper machine having a dewatering mechanism with a dewatering blade immediately after initial dewatering with a forming roll, and an on-machine coater. In the case where the coated paper for printing is produced continuously, the amount of liquid absorbed by the size press can be suppressed, especially when the coated paper for printing with a high filler content is made under high speed conditions. To provide a method for producing coated paper that can greatly improve the yield on the wire of fine components such as fine pulp fibers and fillers in paper stock, has good interlayer strength, and has good printing quality such as blister resistance. With the goal.

Then, the inventors of the present invention, when making a printing base paper using a roll and blade former type gap former type paper machine having a dewatering mechanism with a dewatering blade immediately after initial dewatering with a forming roll, yields. As a result of earnest research on improvement and quality improvement as a coating base paper, (a) a copolymer having a quaternization rate of 40 mol% or more obtained by polymerizing a monomer component containing a hydrophobic monomer and a cationic monomer; By using a mixture of fillers and (b) an ultra-high molecular weight cationic polyacrylamide material, the amount of liquid absorbed by the size press can be suppressed, and the yield can be improved while the distribution of fine fibers and fillers in the paper layer is uniform. And found that it is possible to produce printing paper with good interlayer strength and good printing quality such as blister resistance, and completed the present invention.
(1) Immediately after the initial dewatering by the forming roll, using a roll and blade former type gap former type paper machine and an on-machine coater having a dewatering mechanism by a dewatering blade, at a speed of 1300 m / min or more by a neutral papermaking method. A method for producing a coated paper for printing, wherein (a) a quaternization rate obtained by polymerizing a monomer component containing a hydrophobic monomer and a cationic monomer is 40 mol% or more. A method for producing a coated paper for printing, comprising adding a mixture of a polymer and a filler, and (b) an emulsion-type cationic polyacrylamide having a weight average molecular weight of 10,000,000 or more by an intrinsic viscosity method.
(2) The production method according to (1), wherein the copolymer is a cationic copolymer or an amphoteric copolymer further containing an anionic monomer.
(3) The production method according to any one of (1) and (2), wherein the filler is calcium carbonate.
(4) The manufacturing method according to any one of (1) to (3), wherein coating is first performed on a base paper using a rod metering size press type coater.
(5) The manufacturing method according to any one of (1) to (4), wherein an addition amount of the copolymer is 0.05 to 0.5% by weight with respect to a pulp solid content.
(6) The manufacturing method according to any one of (1) to (5), wherein a base paper basis weight of the coated paper for printing is 30 to 70 g / m2.
(7) The manufacturing method according to any one of (1) to (6), wherein the raw pulp contains 20% by weight or more of deinked pulp (DIP).

  According to the present invention, high yield and interlayer strength can be achieved. In particular, when the present invention is applied to the production of a coated paper for printing with a high paper making speed and a high filler content in the paper, the effects of the present invention can be greatly enjoyed. In the case where a gap former type paper machine or a twin wire type paper machine is used when the paper making speed is particularly high, the present invention is provided with a film transfer roll coater such as a metering size press coater or a gate row coater. The size press is particularly suitable when coating with an on-machine coater equipped, and when applying a coating solution with an online blade coater following an on-machine coater equipped with a film transfer roll coater. Coated paper with good print quality such as blistering resistance, which can significantly reduce the amount of water absorbed, greatly improve the yield of fine components such as fine pulp fibers and fillers on the wire. Can be obtained.

  The present invention uses a gap-former type paper machine of a roll and blade former type and an on-machine coater having a dewatering mechanism with a dewatering blade immediately after initial dewatering with a forming roll, and a papermaking speed of 1300 m / min by a neutral papermaking method. The present invention relates to a method for continuously producing coated paper for printing. In the present invention, (a) a papermaking additive which is a mixture of a copolymer having a quaternization rate of 40 mol% or more obtained by polymerizing a monomer component containing a hydrophobic monomer and a cationic monomer, and a filler; (B) An emulsion-type cationic polyacrylamide material having a weight average molecular weight of 10 million or more according to the intrinsic viscosity method is added to the stock.

If papermaking printing for coated base paper at a high speed conditions using the papermaking conventional gap former type paper machine, although dehydration sidedness of the paper to be done from both sides of the paper layer becomes good, the paper surface of the fine component There have been problems such as localization of parts and unstable operation due to a decrease in yield. In order to remedy this problem, a gap-former type paper machine of the roll and blade former type that can uniformize the fine components in the paper layer has been proposed, but the balance of dewatering is adjusted as the yield of fine fibers increases greatly Because it was not possible, localization of fine components in the paper layer occurred, causing problems such as an increase in the difference between the front and back surfaces.

  Also, the yield of paper stock tends to decrease as the paper making speed of the paper machine is high, the paper filling rate is high, and the basis weight is low, but the current paper production method is high speed, high ash content, low basis weight. The same applies to base paper for coated paper for printing.

  The method for producing a coated paper for printing of the present invention is a production method using a gap former type paper machine of a roll and blade former type having a dewatering mechanism using a dewatering blade immediately after initial dewatering using a forming roll. In particular, the production method of the present invention is a production method with a high paper making speed using the above-mentioned roll-and-former type gap former type paper machine, and preferably has a high paper filling rate.

  The paper-making speed of the present invention is 1300 m / min or more, but the effect obtained by applying the present invention is particularly great in high-speed papermaking, so the present invention is 1500 m / min or more, more preferably 1600 m / min or more. It is suitable for papermaking, and papermaking at about 1800-2500 m / min is also possible.

As described above , the present invention provides a papermaking additive comprising : (a) a copolymer having a quaternization rate of 40 mol% or more obtained by polymerizing a monomer component containing a hydrophobic monomer and a cationic monomer; and a filler. The mixture is added to the stock as a papermaking additive. The ionicity of the copolymer used for the papermaking additive (a) of the present invention is cationic because it contains a cationic monomer, or amphoteric when it further contains an anionic monomer. By mixing such a copolymer and filler, water repellency can be imparted to the filler, and the filler combined with the copolymer having a cationic group can be adsorbed to the anionic pulp. Both the filler and the filler can be efficiently hydrophobized and the paper size can be improved. As a result of the improvement in paper size, in the present invention, the amount of liquid absorbed by the size press can be suppressed, paper breakage can be prevented, and the paper making speed can be increased.

<Monomer composition of copolymer>
The copolymer used for the papermaking additive (a) of the present invention is polymerized from monomer components essentially comprising the hydrophobic monomer (A) and the cationic monomer (B).

The hydrophobic monomer (A) is styrene or a derivative thereof, (meth) acrylonitrile, an alkyl ester of (meth) acrylic acid, etc., and in particular, styrene or a derivative thereof, (meth) acrylonitrile, C of (meth) acrylic acid. ₁ -C ₁₂ alkyl esters are preferred.

  In the present invention, “(meth) acryl” means “acryl” or “methacryl”. Similarly, “(meth) acrylo” means “acrylo” or “methacrylo” and “(meth) ) Acrylate "means" acrylate "or" methacrylate ".

  Examples of the styrene or derivatives thereof include styrene, α-methyl styrene, vinyl toluene, ethyl vinyl toluene, chloromethyl styrene, vinyl pyridine and the like, and styrene is preferable.

Examples of the (meth) _C 1 _{-C 12} alkyl esters of acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n- butyl (meth) acrylate, iso- butyl (meth) acrylate , Hydrocarbon esters such as t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and the like. A (meth) acrylic acid ester containing a cyclic or aromatic hydrocarbon group can also be used. Particularly preferred are methyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate.

  The cationic monomer (B) contains a primary to tertiary amino group-containing (meth) acrylamide, a primary to tertiary amino group-containing (meth) acrylate, a quaternary ammonium base-containing (meth) acrylamide, and a quaternary ammonium base (meta). ) One or more cationic groups in the molecule, such as acrylate, diallyldialkylammonium halide, etc., especially tertiary amino group-containing (meth) acrylamide, tertiary amino group-containing (meth) acrylate Diallyldialkylammonium halides are preferred.

  Examples of the tertiary amino group-containing (meth) acrylamide include dialkylaminoalkyl (meth) such as dimethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, and diethylaminopropyl (meth) acrylamide. Examples include acrylamide.

  Examples of the tertiary amino group-containing (meth) acrylates include dialkylaminoalkyl (meth) such as dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and diethylaminopropyl (meth) acrylate. An acrylate etc. are mentioned.

  The primary or secondary amino group-containing (meth) acrylamide is a primary amino group-containing (meth) acrylamide such as aminoethyl (meth) acrylamide, or methylaminoethyl (meth) acrylamide, ethylaminoethyl ( Secondary amino group-containing (meth) acrylamides such as meth) acrylamide and t-butylaminoethyl (meth) acrylamide are exemplified.

  Examples of the primary or secondary amino group-containing (meth) acrylate include primary amino group-containing (meth) acrylates such as aminoethyl (meth) acrylate, methylaminoethyl (meth) acrylate, and ethylaminoethyl (meth). Examples thereof include secondary amino group-containing (meth) acrylates such as acrylate and t-butylaminoethyl (meth) acrylate.

  As the quaternary ammonium base-containing (meth) acrylamide and quaternary ammonium base-containing (meth) acrylate, tertiary amino group-containing (meth) acrylamide or tertiary amino group-containing (meth) acrylate, methyl chloride, benzyl chloride, Mono-quaternary base-containing monomers quaternized with a quaternizing agent such as methyl sulfate or epichlorohydrin. Specifically, acrylamidopropyltrimethylammonium chloride, acrylamidopropylbenzyldimethylammonium chloride, methacryloyloxyethyldimethylbenzylammonium chloride, acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloylaminoethyltrimethylammonium chloride, (meth) acryloyl Examples include aminoethyltriethylammonium chloride, (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyltriethylammonium chloride, and the like.

  As a monomer component which comprises the said cationic copolymer, another monomer can be used as needed other than the said hydrophobic monomer (A) and the said cationic monomer (B). Examples of other monomers include hydroxyl-containing (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, and iso-propyl. Examples include amide group-containing monomers such as (meth) acrylamide and vinyl acetate.

  The monomer component constituting the cationic copolymer can be used alone or in combination. The composition ratio of the monomer component can be arbitrarily set within a range in which appropriate water repellency can be imparted to the filler, but the content of the hydrophobic monomer (A) is about 60 to 90% by weight, and the content of the cationic monomer (B) Is preferably about 10 to 40% by weight.

  The copolymer of the present invention can be made into an amphoteric copolymer by polymerizing from a monomer component containing an anionic monomer (C) in addition to a hydrophobic monomer (A) and a cationic monomer (B). .

  Examples of the anionic monomer (C) include α, β-unsaturated carboxylic acids and α, β-unsaturated sulfonic acids. Examples of the α, β-unsaturated carboxylic acids include (meth) acrylic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, (anhydrous) citraconic acid, its sodium, potassium, and ammonium salts. Examples of the α, β-unsaturated sulfonic acids include vinyl sulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid, sulfopropyl (meth) acrylate, 2- (meth) acrylamide-2-methylpropane sulfonic acid, and salts thereof Etc.

  In the case of the monomer component constituting the amphoteric copolymer, each monomer can be used alone or in combination. The composition ratio of the monomer component can be arbitrarily set within a range in which appropriate water repellency can be imparted to the filler, but the content of the hydrophobic monomer (A) is about 60 to 90% by weight, and the content of the cationic monomer (B) Is preferably about 9.8 to 40% by weight, and the content of the anionic monomer (C) is preferably about 0.2 to 10% by weight.

  In the monomer component constituting the amphoteric copolymer, the ratio of the anionic equivalent of the anionic monomer (C) to the cation equivalent of the cationic monomer (B) needs to be 0.1 to 90%. . A preferable equivalent ratio is 5 to 20%, more preferably 5 to 15%. That is, the amphoteric copolymer in the present invention is more likely to exhibit a size effect when the cation equivalent is richer and the anion equivalent is smaller. If the ratio of the anion equivalent to the cation equivalent is too large, the anionic monomer (C) forms an ionic complex with the cation portion, which reduces the action of the cation on the pulp fiber, and there is a possibility that the size property will not be expressed. An anionic equivalent of the anionic monomer (C) within the above range is required.

<Fourth grade>
The copolymer of the present invention can be obtained by polymerizing the above monomer components, and it is important that the quaternization rate is 40 mol% or more. The quaternization rate is preferably 50 to 100 mol%. If the quaternization rate is less than 40 mol%, it may be difficult to obtain an effective water repellency imparting effect to the filler and pulp fiber.

  In quaternization of the cationic copolymer or amphoteric copolymer, for example, a monomer component containing a tertiary amino group-containing monomer as the cationic monomer (B) is polymerized, and then the obtained copolymer is converted to 4 It may be quaternized with a classifier, or may be polymerized using a quaternary ammonium base-containing monomer obtained by quaternization in advance as the cationic monomer (B). As the quaternizing agent, methyl chloride, benzyl chloride, epichlorohydrin and the like can be used.

<Filler>
The papermaking additive (a) of the present invention is obtained by mixing the copolymer and filler. As a filler to be used, a known material can be arbitrarily used. For example, calcium carbonate, clay, silica, kaolin, magnesium carbonate, barium carbonate, barium sulfate, aluminum hydroxide, zinc oxide, titanium oxide and other inorganic fillers, urea-formalin resin, melamine resin, polystyrene resin, phenol resin, etc. Organic fillers can be used alone or in combination. In addition, recycled fillers made from papermaking sludge, deinking floss, etc. can also be used. In the present invention, it is preferable to use calcium carbonate because the cationic copolymer and the amphoteric copolymer are excellent in action on calcium carbonate, and because calcium carbonate is inexpensive and excellent in optical properties. . As calcium carbonate, a calcium carbonate-silica composite (for example, a light calcium carbonate-silica composite disclosed in Japanese Patent Application Laid-Open No. 2003-212539 or Japanese Patent Application Laid-Open No. 2005-219945) can also be used.

  The copolymer and the filler are usually mixed by mixing and stirring the aqueous solution of the copolymer and the filler slurry in advance before adding to the pulp slurry. The mixing temperature is preferably about 10 to 50 ° C., and the mixing time is preferably 1 minute or more.

  The ratio of the copolymer to 100 parts by weight of the filler when mixing the copolymer and filler is preferably 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, and still more preferably. 0.2 to 2 parts by weight. If the proportion of the copolymer is too small, a sufficient size effect may not be obtained. On the other hand, even if the proportion of the copolymer is made larger than the above range, there is not much change in the obtained size improvement effect, and the cost tends to be wasted.

Cationic Polyacrylamide Yield Improvement Agent In addition to the filler / copolymer mixture described above, the present invention uses (b) an emulsion type cationic polyacrylamide having a weight average molecular weight of 10 million or more by the intrinsic viscosity method. As described above, by adding a copolymer having a cationic group and a filler in combination, the size of the paper is increased, and the amount of liquid absorption in the size press can be suppressed. However, as in the present invention, when paper is made under a high ash content / high speed condition by a gap former paper machine, the ash content yield is low, so the yield of the above combination of the copolymer having a cationic group and the filler is low. As a result, it was difficult to obtain the required size. Therefore, as in the present invention, when (b) an emulsion type cationic polyacrylamide having a weight average molecular weight of 10 million or more by the intrinsic viscosity method is used, the ash yield is improved and the effect of the above combination is sufficiently exhibited. It was found that the size of the paper is also improved.

  In the present invention, paper is made by adding a linear or branched cationic polyacrylamide (PAM) substance having a weight average molecular weight of 10 million or more, preferably 12 million or more by an intrinsic viscosity method, as a yield improver to a paper stock. . If the molecular weight of the cationic polyacrylamide-based yield improver of the present invention is 15 million or more, a coated base paper having excellent formation and interlayer strength can be produced at a high yield without using anionic fine particles described later. This is preferable.

  The form of the cationic polyacrylamide type material used in the production method of the present invention is an emulsion type, but this specific composition is particularly limited as long as it contains an acrylamide monomer unit as a structural unit. However, for example, a copolymer of quaternary ammonium salt of acrylate ester and acrylamide, or a quaternized ammonium salt after copolymerization of acrylamide and acrylate ester may be mentioned. The cationic charge density of the cationic polyacrylamide-based material is not particularly limited. However, since the base material of the printing base paper contains a large amount of anionic substances derived from the coating liquid, its cation requirement is extremely high. From the viewpoint of increasing the yield, the cation charge density is preferably high, specifically 1.0 meq / g or more is preferable, 1.5 meq / g or more is more preferable, and 2.0 meq / g or more is more preferable. If the cation charge density exceeds 10.0 meq / g, the charge balance in the system may be reversed, which is not suitable.

  In the paper machine pre-treatment process, a fresh filler is usually added to the paper stock obtained by mixing the pulp raw material and the internally added paper making chemicals with a mixer, and the mixture is uniformly mixed. Therefore, the addition location of the cationic polyacrylamide-based material is preferably between after the filler is added and before the paper machine stock inlet.

  Further, the cationic PAM of the present invention can be used in combination with anionic fine particles. Examples of the anionic fine particles include inorganic fine particles such as bentonite, colloidal silica, polysilicic acid, polysilicic acid or polysilicate microgel, and modified aluminum thereof, and a particle size of 100 μm or less, which is a so-called micropolymer in which acrylamide is cross-linked. Organic fine particles can be mentioned, and one or more anionic fine particles can be used. Preferable inorganic fine particles are bentonite or colloidal silica. As the organic fine particles, a copolymer of acrylic acid and acrylamide is preferable. In addition, bentonite or colloidal silica is preferred when inorganic fine particles and organic fine particles are used in combination, and a copolymer of acrylic acid and acrylamide is also preferred as the organic fine particles in this case.

  When the cationic polyacrylamide type yield improver and the anionic fine particle yield improver are used in combination, it is preferable to add the anionic fine particles after adding the cationic polyacrylamide type substance. The addition location of the cationic polyacrylamide yield improver of the present invention is preferably between after the filler is added and before the primary screen.

  The amount of the cationic polyacrylamide-based substance added as a retention agent is not properly determined because it is appropriately determined according to the properties of the stock and the paper making speed. 50 to 750 ppm, preferably 50 to 600 ppm, more preferably 100 to 600 ppm, and still more preferably 100 to 500 ppm. If the amount of the cationic polymer substance added is less than 50 ppm, the formation of the coating base paper for printing is good, but a sufficient yield of fine components cannot be obtained. If it is added in excess of 750 ppm, the yield of fine components increases, but the formation deteriorates, and printing defects such as printing unevenness caused by uneven formation occur.

Papermaking raw materials The pulp raw materials for the printing paper produced in the present invention are not particularly limited, and are mechanical pulp (MP), deinked pulp (DIP), hardwood kraft pulp (LKP), and softwood kraft pulp (NKP). Any material may be used as long as it is generally used as a papermaking raw material for printing paper, and one or two or more of these may be used as appropriate. Examples of mechanical pulp include groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), chemiground pulp (CGP), and semi-chemical pulp (SCP). . The deinked pulp may be any deinked pulp made from high-quality paper, medium-quality paper, low-grade paper, newspaper, flyers, magazines, etc., or unselected waste paper mixed with these. Absent. In the present invention, even if the deinked pulp is blended in an amount of 20% by weight or more, 30% by weight or more, and further 50% by weight or more, the effect of improving formation, yield, and interlayer strength can be exhibited. .

  The filler used in the present invention can be arbitrarily selected from known ones, and particles generally called inorganic fillers and organic fillers, or a mixture thereof can be used. Specifically, as an inorganic filler, for example, heavy calcium carbonate, light calcium carbonate, clay, silica, light calcium carbonate-silica composite, kaolin, calcined kaolin, deramikaolin, magnesium carbonate, barium carbonate, barium sulfate, water Amorphous silica, sodium silicate and mineral acid produced by neutralization of aluminum oxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, talc, zinc stearate, titanium oxide, sodium silicate mineral Silica (white carbon, silica / calcium carbonate composite, silica / titanium dioxide composite, etc.), titanium dioxide, white clay, bentonite, diatomaceous earth, calcium sulfate, and ash obtained from the deinking process are regenerated and used. Inorganic fillers and silica and calcium carbonate in the process of regeneration Inorganic filler and the like in complex with. In addition, as a calcium carbonate-silica composite, the composite as described in Unexamined-Japanese-Patent No. 2003-212539 and Unexamined-Japanese-Patent No. 2005-219945 can be illustrated. In addition to calcium carbonate and / or light calcium carbonate-silica composite, amorphous silica such as white carbon may be used in combination. Among these, calcium carbonate and light calcium carbonate-silica composite, which are typical fillers for neutral papermaking and alkaline papermaking, are preferably used. Organic fillers include melamine resins, urea-formalin resins, polystyrene resins, phenolic resins, fine hollow particles, acrylamide composites, wood-derived substances (fine fibers, microfibril fibers, powder kenaf), modified insolubilized starch, Examples include gelatinized starch. These may be used alone or in combination of two or more.

  1-40 solid content weight% is preferable, as for the filler content in the paper of the printing coating base paper manufactured by this invention, 5-35 solid content weight% is more preferable, and 10-35 solid content weight% is further more preferable. In papermaking, the yield decreases as the filler content in the paper increases. Therefore, the effect of the present invention is greater when the present invention is applied to the production of a printing base paper having a high filler content in the paper.

Neutral papermaking The production method of the present invention is neutral papermaking. In the present invention, the neutral papermaking method is to make paper using a paper system having a pH of 6.0 to 9.0. In a more preferred embodiment, the present invention performs paper making using a paper stock having a pH of 7.0 to 8.5. In addition, since the present invention is neutral papermaking, it is particularly preferable to internally add calcium carbonate as a filler. With calcium carbonate, a coated base paper having high whiteness and high opacity can be obtained at low cost.

As the internal additive chemicals , chemicals such as a dry paper strength improver, a paper bulking agent, a wet paper strength improver, a coagulant, a drainage improver, and a dye may be used as necessary. Examples of the dry paper strength improver include polyacrylamide and cationized starch, and examples of the wet paper strength improver include polyamidoamine epichlorohydrin. Coagulants include polyethyleneimine and modified polyethyleneimines containing tertiary and / or quaternary ammonium groups, polyalkyleneimines, dicyandiamide polymers, polyamines, polyamine / epichlorohydrin polymers, and dialkyldiallyl quaternary ammonium monomers, dialkylamino Cationic properties such as alkyl acrylates, dialkylaminoalkyl methacrylates, dialkylaminoalkylacrylamides and polymers of acrylamide and acrylamide, polymers of monoamines and epihalohydrin, polymers with polyvinylamine and vinylamine moieties, and mixtures thereof In addition to the polymers mentioned above, an anion group such as a carboxyl group or a sulfone group is copolymerized in the polymer molecule. Nritchi a zwitterionic polymers, and a mixture of cationic polymer and an anionic or zwitterionic polymer. Cationic, amphoteric and anionic modified starches can also be used. As the sizing agent, only a papermaking additive may be added, or it may be used in combination with neutral rosin, AKD, or ASA. In addition, conventional internal additives such as drainage improvers, colorants, dyes, fluorescent dyes, and paper bulking agents for bulking (lowering the density of) paper should be used. Can do. These chemicals are added within a range that does not affect the formation and operability. Specific examples of the bulking agent for paper include oil-based nonionic surfactants, sugar alcohol-based nonionic surfactants, sugar-based nonionic surfactants, polyhydric alcohol-type nonionic surfactants, polyhydric alcohols. And fatty acid ester compound, higher alcohol or polyoxyalkylene adduct of higher fatty acid, polyoxyalkylene adduct of higher fatty acid ester, polyoxyalkylene adduct of polyhydric alcohol and fatty acid ester compound, fatty acid polyamidoamine, fatty acid diamidoamine And fatty acid monoamidoamines, and the like are not particularly limited. Since the paper strength tends to decrease due to the use of the bulking agent, it is preferable to apply the present invention to the paper stock containing the bulking agent from the viewpoint of maintaining paper strength.

Forming part of the manufacturing method of a paper machine The present invention is a gap former of roll and blade type, the first dewatering place in the lap area of a forming roll having a vacuum, the blade dewatering line by pressing the blade module immediately thereafter Is called. This mechanism makes it possible to perform dewatering slower than that of a conventional former, so that paper having a uniform paper layer structure and texture can be obtained. If the diameter of the forming roll used at this time is small, a sufficient holding angle cannot be obtained, and adjustment of dewatering becomes insufficient, so that it is preferably 1500 mm or more. In addition to a dewatering mechanism using a forming roll or a blade, dryness can be adjusted by appropriately using a dewatering device such as a suction unit or a high vacuum suction box in the subsequent stage. The dehydrating conditions such as blade pressure are not particularly limited and can be set as appropriate within the normal operating range.

  The press part in the production method of the present invention preferably uses a shoe press. When the paper making speed is high, the dryness after pressing can be improved by more preferably processing in two or more stages. Strength such as length is improved. The shoe press of the present invention may have a nip width in the range of about 150 to 250 mm, and allows a sheet to pass between a press roll that is rotationally driven and a pressure shoe that is hydraulically pushed up, and a sleeve between the felt and the pressure shoe. It may be the type that runs. The press pressure can be appropriately adjusted in consideration of the moisture at the press outlet and the difference between the front and back sides, preferably 400 to 1200 kN / m, more preferably 1000 to 1200 kN / m.

  The paper machine pre-dryer and after-dryer can also use a public apparatus, and the drying conditions are not particularly limited, and can be appropriately set within the normal operating range.

Coated paper In the present invention, a coated base paper is manufactured using the raw materials and apparatuses as described above, and a coated paper can also be manufactured by applying a pigment coating layer to the coated base paper. In one aspect, the present invention is a method for producing a coated paper for printing, which comprises applying a coating liquid to the coated base paper obtained according to the present invention. When a coated paper is obtained according to the present invention, an on-machine coater is used. However, according to the present invention, even if a coat broke or the like is used as a papermaking raw material, the operability is not lowered. Suitable for machine application. In addition, since the present invention continuously produces the coating process online from papermaking using a gap former type paper machine equipped with an on-machine coater, the production efficiency is extremely high.

  When the coated paper is produced according to the present invention, the number of pigment coating layers may be one or plural.

  When providing a plurality of pigment coating layers in the present invention, heavy calcium carbonate can be suitably used for the pigment used in the primer coating liquid mainly composed of pigment and adhesive, but depending on the required quality Use together with light calcium carbonate, kaolin, clay, talc, satin white, plastic pigment, titanium dioxide, etc. In addition, the adhesive used in the pigment coating liquid includes various copolymer emulsions such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, and synthetic systems such as polyvinyl alcohol and maleic anhydride copolymer. Adhesive, oxidized starch, esterified starch, enzyme-modified starch, etherified starch, cold water soluble starch obtained by flash drying them, and the like are used. In the pigment coating liquid of the present invention, various auxiliary agents blended in ordinary coating paper pigments such as a dispersant, a thickener, a water retention agent, an antifoaming agent, and a water resistance agent may be used.

The coating amount of the undercoat pigment coating liquid is preferably applied in the range of 0.7 to 10.0 g / m ² in terms of solid content per side of the base paper, more preferably 1.0 to 5.0 g / m. ² are most preferably coated in the range of 2-5 g / ^{m 2.} Coating with an amount of less than 0.7 g / m ² is difficult due to the limitations of the apparatus, and when the coating solution concentration is lowered, the penetration of the coating solution into the base paper increases and the surface properties are reduced. Cheap. When applying an amount larger than 10 g / m ² , it is necessary to increase the concentration of the coating solution, and it is difficult to control the coating amount on the apparatus. The coated paper dried after the undercoating may be subjected to a pre-calender treatment with a soft calender or the like before the application of the topcoat pigment coating solution.

Further, the pigment, adhesive composition, blending amount, coating amount and the like of the topcoat pigment coating solution are not particularly limited, and generally used pigments and adhesives may be used. The coating solution concentration is preferably 55 to 70%, and the coating amount is usually preferably 6 to 20 g / m ² , more preferably 6 to 14 g / m ² in terms of solid content on one side. The top coating apparatus is not particularly limited, but a fountain blade or a roll application blade is usually used, and may be an off coater or an on-machine coater.

  The coated paper that has been dried after being coated with the topcoat pigment coating solution is glossed by a surface treatment process such as a super calender or a soft calender as usual. There are no particular limitations on the type and processing conditions of the calendar device, and publicly available devices such as ordinary calenders made of metal rolls, soft nip calenders, and high-temperature soft nip calenders are selected as appropriate, depending on the quality target value of the printing paper. The conditions may be set within the controllable range of the apparatus.

The coated paper for printing of the present invention thus obtained is excellent in printing quality such as blister resistance. Although not limited to the basis weight of the coated paper, is usually 30 to 120 g / ^{m 2,} preferably 35~100g / ^{m 2,} more preferably one that more effective at 40 and 80 g / ^{m 2} is there. The basis weight of the coating base paper is not particularly limited, but is usually 20 to 80 g / ^{m 2,} preferably 25~60g / ^{m 2,} more preferably from 25 to 50 g / ^{m 2.}

  Moreover, the coating paper manufactured using the printing base paper manufactured by this invention can be used conveniently for various printing uses, such as for offset printing and gravure printing.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, naturally this invention is not limited to these. In the examples, “parts” and “%” respectively represent “parts by weight” and “% by weight” unless otherwise specified.

<Measurement method>
(1) Yield Measurement Method The solid content concentration and the ash concentration were measured for the stock inlet raw material and the white water that passed through the wire (referred to as white water under the wire). The ash content was measured by ashing the solid content of the stock inlet raw material and wire white water at 525 ° C.

  Paper yield was measured by the following formula (1), and ash yield was measured by the following formula (2).

(2) Measuring method of paper formation The formation of paper was evaluated by the total land FMT-III (light transmission fluctuation method) manufactured by Nomura Corporation. In addition, it shows that a formation is so favorable that a measured value is small.

(3) Measuring method of interlaminar strength of paper
Interlaminar strength was measured with L & W ZD Tensile Tester SE 155 (Lorentzen & Wettre).

(4) Size press liquid absorption The size press liquid absorption was measured with the online liquid absorption meter installed in the rod metering size press.

(5) Printing evaluation Using an offset rotary printing press (4 colors, Toshiba B2T600) with an off-wheel printing ink (Reo Echo SOY M manufactured by Toyo Ink Manufacturing Co., Ltd.) at a printing speed of 500 rpm and a paper surface temperature of 120 ° C during drying. Printed. Ink solidity of the obtained printed matter was visually evaluated with respect to the halftone dot portion of black 50% (◯: good, Δ: slightly inferior, ×: inferior). Furthermore, the presence or absence of occurrence of blisters was confirmed for the four-color solid portion (◯: no blister occurred, Δ: almost no blister occurred x: blister occurred).

<Synthesis of cationic copolymer and amphoteric copolymer>
(1) Synthesis example 1
In a 0.5 liter four-necked flask equipped with a thermometer, stirrer, reflux condenser and nitrogen inlet tube, 30 parts of isopropanol, 50 parts of styrene, 20 parts of methyl methacrylate, 10 parts of butyl acrylate, dimethylaminoethyl methacrylate 20 And 1.5 parts of n-dodecyl mercaptan were added and heated with stirring to raise the temperature to 85 ° C. Next, while maintaining the temperature at 85 to 90 ° C., a polymerization initiator solution consisting of 1.5 parts of t-butyl peroxyethyl hexanate and 3 parts of isopropanol was dropped in 3 hours, and aged for 1 hour. Was completed. Thereafter, while maintaining the temperature at 80 ° C., 8.5 parts of 90% acetic acid for neutralizing the cationic copolymer and 260 parts of warm water were added over 30 minutes and maintained for 1 hour, and 9.5 parts of epichlorohydrin was added. Then, it was kept at 80 ° C. for 2 hours to completely dissolve it.

  After cooling, water was added to obtain a cationic copolymer aqueous solution having a solid content of 20%.

(2) Synthesis example 2
In a 0.5 liter four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen introduction tube, 25 parts of isopropanol and 7.6 parts of 90% acetic acid were placed and heated to 80 ° C. with stirring. . Next, 1.5 parts of n-dodecyl mercaptan and 1 part of azobisisobutyronitrile were dissolved in a monomer mixture of 30 parts of styrene, 50 parts of iso-butyl methacrylate, 1 part of maleic anhydride and 19 parts of dimethylaminoethyl methacrylate. The entire amount of the mixed solution was dropped in 3 hours while maintaining the temperature inside the flask at 80 to 85 ° C., and aged for 1 hour to complete the reaction. Thereafter, the temperature was kept at 80 ° C., 300 parts of warm water was added and kept for 1 hour, 9 parts of epichlorohydrin was added and kept at 80 ° C. for 2 hours, and completely water-solubilized. After cooling, water was added to obtain an amphoteric copolymer aqueous solution having a solid content of 20%.

<Manufacture of coated paper for printing>
(1) Paper machine: A gap-former type paper machine of a roll and blade former type or a gap-former type paper machine of a blade former type.

(2) Pulp raw material composition: Conifer kraft pulp (freeness CSF = 600ml) 30%, deinked pulp (freeness CSF = 240ml) 70%
(3) Filler ratio of base paper (base paper ash content): Rosetta-type light calcium carbonate (average particle size 2.5 μm) was used, and the addition amount was adjusted as appropriate so as to achieve the target paper ash content.

  (4) Undercoat coating liquid in rod metering size press: 100 parts of heavy calcium carbonate (Shiraishi Calcium Co., Ltd., Hydrocarbon 90), dispersant (Toa Gosei Co., Ltd., Aron T-40) After adding 0.3 part of water and dispersing in water using a cowless disperser, 15 parts of phosphate esterified starch and 3 parts of styrene / butadiene latex are blended as an adhesive, and an undercoat pigment having a solid content concentration of 48%. A coating solution was prepared.

  (5) Topcoat coating solution: 70 parts of the above heavy calcium carbonate and 30 parts of kaolin are added 0.3 part of sodium polyacrylate dispersing agent and dispersed in water using a cowless disperser. As an adhesive, 5 parts of phosphate esterified starch and 10 parts of styrene / butadiene copolymer latex were blended to prepare a topcoat pigment coating solution having a solid content of 65%.

<Evaluation of coated paper>
With respect to the coated paper after coating the coated base paper with a paint, the number of paper surface dirts of 0.05 mm or more was measured using SpecScan 2000 (Apoge Technology) based on the image analysis method.

  Using an offset rotary printing press (B2T600, 4 colors, manufactured by Toshiba), printing was performed at a printing speed of 500 rpm and a paper surface temperature of 120 ° C. during drying using ink for off-wheel printing (Reo Echo SOY M, manufactured by Toyo Ink Co., Ltd.). The print reproducibility of the black 50% halftone dot portion of the obtained printed matter was visually evaluated (◯: good, Δ: slightly inferior, ×: inferior).

<Creation of pigment coating liquid>
-Undercoat coating solution: 0.3 parts of dispersant (Aron T-40, Toagosei Co., Ltd.) is added to 100 parts of heavy calcium carbonate (HydroCarbo 90, Shiraishi Calcium Co., Ltd.) After dispersing in water using a cowless disperser, 15 parts of phosphate esterified starch and 3 parts of styrene-butadiene latex were blended as an adhesive to prepare an undercoat pigment coating solution having a solid content concentration of 48%.

  ・ Coating solution for top coating: 70 parts of the above heavy calcium carbonate and 30 parts of kaolin are added 0.3 part of sodium polyacrylate dispersing agent, dispersed in water using a cowless disperser, and bonded. As an agent, 5 parts of phosphate esterified starch and 10 parts of styrene / butadiene copolymer latex were blended to prepare a topcoat pigment coating solution having a solid content of 65%.

Example 1
A coagulant (N7527, manufactured by Katayama Narco Co., Ltd.) is added to the pulp, 250 ppm per solid weight of the paper stock in the coat broke, 150 ppm per solid weight of the paper stock in the Mix chest, and amphoteric polyacrylamide as a synthetic paper strength enhancer for internal use. (DS4340, manufactured by Seiko PMC Co., Ltd.) was added at 0.2% per weight of the solid content of the paper, and the cationic copolymer was prepared from the aqueous solution of the cationic copolymer prepared in Synthesis Example 1 and the paper additive prepared from light calcium carbonate. A cationic polyacrylamide retention agent having a weight average molecular weight of 20 million as determined by the intrinsic viscosity method (Rializer R300 manufactured by Somaar Co., Ltd., cationic charge density 1.96). meq / g) is added to 350ppm of the solid weight of the stock, has two tandem shoe presses, and has a forming roll diameter of 1600mm. Machine speed 1,600 m / min in atomic basis weight 34g / m 2 using a gap former type paper machine ^to obtain a printing coating base paper in the paper base paper ash content 15%. Then, use a rod metering size press coater to apply 2.5 g / m ² double-sided coating on one side, and then use a blade coater to apply 6 g / m ² double-sided coating on one side. did. As the surface treatment, high-temperature soft nip calendering was performed under the conditions of a metal roll surface temperature of 150 ° C., a linear pressure of 300 kg / cm, and a calender nip number of 6 nips to obtain a coated paper for printing having a basis weight of 51 g / m ² . In this example, a gap former type paper machine equipped with an on-machine coater was used to continuously produce the coating process online from paper.

Example 2
A coated paper for printing was obtained in the same manner as in Example 1 except that the amphoteric copolymer of Synthesis Example 2 was used instead of the cationic copolymer of Synthesis Example 1.

Example 3
A coated paper for printing was obtained in the same manner as in Example 1 except that the paper making speed in Example 1 was 1300 m / min.

Comparative Example 1
A coated paper for printing was obtained in the same manner as in Example 1, except that a mixture of AKD sizing agent (manufactured by Seiko PMC) and light calcium carbonate was used in place of the paper additive of Example 1.

Comparative Example 2
A coated paper for printing was obtained in the same manner as in Example 1 except that DR5700 (manufactured by Hymo Co., Ltd., molecular weight: 7 million, cationic polyacrylamide, charge density: 2.2 meq / g) was used as the yielding agent of Example 1.

Comparative Example 3
A coated paper for printing was obtained in the same manner as in Example 1 except that the paper making speed in Example 2 was 1300 m / min.

Table 1 shows the results. The stock / ash yield was determined to be very good at 58/28% or more, good at 55/24 to 57/27%, and very bad at 54/26% or less. Size press liquid absorption amount, 5.5 g / ^{m 2} good below poor in 5.6~6.0g / ^{m 2,} it is determined that the very poor at 6.1 g / ^{m 2} or more.

  From Examples 1 to 3, when the paper additive of the present invention was used, the amount of liquid absorbed by the size press was suppressed, and as a result, the ink deposition property was improved. Moreover, when Example 1 and Comparative Example 2 are compared, when a high molecular weight cationic polyacrylamide (R300) is used in combination as a retention agent, the stock and ash yield are particularly improved. For this reason, the yield of fine fibers was improved, and the interlayer strength and blister resistance of the printing paper were improved. On the other hand, Comparative Example 2 had a low yield and poor interlayer strength, blister resistance, and ink depositability.

  In Example 3, it was shown that the yield was further improved by reducing the papermaking speed to 1300 m / min from Example 1, and the size press liquid absorption amount and interlayer strength were also good. In Comparative Example 3, the yield was slightly improved as compared with Comparative Example 2 because the paper making speed was reduced to 1300 m / min, but it was shown that the coated paper having the desired quality as compared with R300 was not obtained. Has been.

Claims (7)

Immediately after the initial dewatering by the forming roll, using a roll and blade former type gap former type paper machine and an on-machine coater having a dewatering mechanism by a dewatering blade, the coating for printing is performed at a speed of 1300 m / min or more by a neutral papermaking method. A method of manufacturing craft paper,
(A) a mixture of a copolymer and a filler having a quaternization ratio of 40 mol% or more obtained by polymerizing a monomer component containing a hydrophobic monomer and a cationic monomer, and (b) A method for producing a coated paper for printing, comprising adding an emulsion type cationic polyacrylamide having a weight average molecular weight of 10 million or more by an intrinsic viscosity method.   The production method according to claim 1, wherein the copolymer is a cationic copolymer or an amphoteric copolymer further containing an anionic monomer.   The production method according to claim 1, wherein the filler is calcium carbonate.   The manufacturing method according to any one of claims 1 to 3, wherein coating is first performed on a base paper using a rod metering size press type coater.   The manufacturing method of any one of Claims 1-4 whose addition amount of the said copolymer is 0.05 to 0.5 weight% with respect to pulp solid content. The base paper basis weight of coated printing paper is 30~70g / ^{m 2,} the production method according to any one of claims 1 to 5.   The manufacturing method of any one of Claims 1-6 in which 20 weight% or more of deinked pulp (DIP) is contained in raw material pulp.