JP2009144272A - Paper and method for producing paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper having good formation, produced in good yield of microfilaments even if a large amount of deinked pulp is formulated, and having little defects by foreign matters, and to provide a method for producing the paper. <P>SOLUTION: The paper contains a polymer compound (a coagulant A) at least in one shape of a network shape, a tree diagram shape and a micell shape and has ≤10 formation index measured by a sheet formation tester. Preferably, the paper contains ≥50 mass% deinked pulp, and has ≤1.8 mm<SP>2</SP>/m<SP>2</SP>impurity area ratio. In another embodiment, the paper contains a linear polymer compound (a coagulant B). The method for producing the paper includes adding the polymer compound (the coagulant A) at least in one shape of the network shape, the tree diagram shape and the micell shape, and the linear polymer compound (the coagulant B) to a pulp slurry containing the ≥50 mass% deinked pulp in order. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to paper with good formation. In particular, the present invention relates to a paper and a method for producing paper, which are preferably used as a base paper for coating, since the deinked pulp has a high blending of 50% by mass or more and has few defects.

  There are two types of paper raw materials used in magazines and flyers, chemical pulp obtained from wood and deinked pulp recycled from old paper, and these materials are mixed to produce paper. In recent years, due to increasing environmental awareness, there is a tendency to use a large amount of deinked pulp while suppressing the amount of chemical pulp that is a natural raw material and leads to deforestation.

  However, deinked pulp contains organic substances such as printing ink, back glue, and adhesive in the coating layer, and these agglomerate in the paper making process to form a pitch, causing a problem of foreign matter. The removal of foreign matters from the waste paper raw material is mainly performed in the deinking process, and foreign matters having a size that can be visually recognized can be removed at this stage. However, it is impossible to completely remove foreign matter in the deinking process. In the papermaking process, which is a subsequent process, minute foreign matter contained in the deinked pulp remains and accumulates inside the papermaking machine without being produced as paper. By doing so, it grows into a foreign substance that can be visually confirmed, resulting in pitch trouble. In other words, how to prevent foreign matter from agglomerating is important for foreign matter troubles derived from deinked pulp.

  Aggregation of foreign matter occurs mainly due to fine fibers adhering to organic matter mixed in the paper machine. In particular, deinked pulp made from recovered recovered paper is used as a raw material for pulp that has been used once as paper and is recycled as a raw material for pulp. It has become.

  In order to suppress the generation of foreign matters, it is important that fine fibers are consumed as a raw material of paper before the foreign matters are aggregated and do not stay inside the paper machine. In order to improve the yield of fine fibers on paper, a method of adding a lot of yield-improving chemicals such as flocculants and coagulants can be considered, but when the blending amount of the yield agent is increased, the flocculant will share the pulp raw material. There is a problem that the appearance of the paper is deteriorated.

As a method for improving the formation, there is a method (Patent Document 1) in which a paint is applied onto a coated base paper having a specified sizing degree, but a sufficient formation cannot be obtained. In addition, as a paper using waste paper pulp, there is a paper containing 10% or more of magazine waste paper (Patent Document 2), but there are problems such as poor yield, generation of foreign matter, and collapse of the formation. Yes, for example, it cannot be blended as high as 50% or more. As described above, there are many problems in producing a paper having a good texture, particularly a paper containing a large amount of deinked pulp, and a paper that has improved these has not yet been obtained.
Japanese Patent Laid-Open No. 09-021095 JP 2004-124279 A

  The main problem to be solved by the present invention relates to a paper and a method for producing paper, which have good formation, good yield of fine fibers even with a large amount of deinked pulp, and few foreign object defects.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
A paper comprising a polymer compound (flocculating agent A) having at least one of a mesh shape, a dendrogram shape, and a micelle shape, and having a formation index measured by a sheet formation tester of 10 or less.

[Invention of Claim 2]
The paper according to claim 1, comprising 50% by mass or more of deinked pulp and having a foreign matter area ratio of 1.8 mm ² / m ² or less.

[Invention of Claim 3]
The paper according to claim 1 or 2, comprising a linear polymer compound (flocculating agent B).

[Invention of Claim 4]
To a pulp slurry containing 50% by mass or more of deinked pulp, a polymer compound (flocculating agent A) having at least one of a mesh shape, a dendrogram shape, and a micelle shape and a linear polymer compound (flocculating agent B) ) Are included in this order.

  According to the present invention, even if a large amount of deinked pulp is blended, the yield of fine fibers is good and there are few foreign matter defects, and the paper and paper manufacturing method is excellent.

Next, the paper according to the embodiment of the present invention will be described using a coated paper as an example.
[Raw pulp]
In the paper of this embodiment, waste paper pulp can be blended with raw material pulp. Waste paper pulp includes, for example, disaggregation / deinked waste paper pulp, disaggregation / deinking / bleached waste paper pulp, etc. produced from magazine waste paper, flyer waste paper, office waste paper, Kami white waste paper, etc., from the viewpoint of environmental protection, It is preferable to blend a large amount of these waste paper pulps, usually 50 to 100% by mass, preferably 70 to 80% by mass.

  Moreover, pulp other than waste paper pulp can also be used, and the kind is not specifically limited, One or two or more kinds can be appropriately selected from these, such as chemical pulp and mechanical pulp.

  As the chemical pulp, for example, unbleached softwood pulp (NUKP), unbleached hardwood pulp (LUKP), bleached softwood pulp (NBKP), bleached hardwood pulp (LBKP) and the like can be used as raw material pulp.

  Examples of the mechanical pulp include stone grand pulp (SGP), pressurized stone grand pulp (PGW), refiner ground pulp (RGP), chemi-ground pulp (CGP), thermo grand pulp (TGP), ground pulp (GP), Thermo mechanical pulp (TMP), Chemi thermo mechanical pulp (CTMP), refiner mechanical pulp (RMP), etc. are mentioned.

  In addition, rag pulp, straw pulp, esparto pulp, bagasse pulp, bamboo pulp, kenaf pulp, and other auxiliary pulps such as bast pulp, etc. made from cotton, flax, hemp, jute, manila hemp, ramie, etc. are used. You may do it.

[Formulation process]
In the preparation process, the above raw pulp needs to be processed to a predetermined quality so that fine fibers and pitch do not remain inside the paper machine.

<Freeness>
The freeness of the deinked pulp is preferably 280 cc to 360 cc, more preferably 300 cc to 340 cc. If it is less than 280 cc, the beating progresses too much, resulting in an increase in the fine fiber yield, and the yield of fine fiber deteriorates. Even if it exceeds 360 cc, the drainage is fast and the fine fiber is difficult to yield, and the inside of the paper machine is soiled and pitched. This is not preferable because trouble is likely to occur.

<Filler>
Inorganic pulp is added to the pulp after beating and adjusting the freeness in order to give the coated paper opacity and flexibility. As the inorganic filler, those generally used for papermaking can be blended. For example, known fillers such as calcium carbonate, titanium oxide, talc, clay, colloidal hydrous silica (commonly known as white carbon), synthetic resin fillers, and the like can be used. There are no particular restrictions on the shape of these inorganic fillers, and various types such as granular, tension, spindle, plate, and amorphous can be used. Regarding the particle size, glossiness, paper flexibility, paper surface, etc. Therefore, generally, talc is preferably 15 μm or less, and calcium carbonate is preferably 3 μm or less.

<Coagulant>
A coagulant can be added to effectively adsorb the filler and fine fibers to the pulp fibers. Examples of the coagulant include organic substances such as polyacrylamide (PAM), polyvinylamine (PVAm), polydiallyldimethylammonium chloride (Polydadomac, PDADMAC), polyamine (PAm), polyethyleneimine (PEI), and polyethylene oxide (PEO). Examples of the polymer coagulant include inorganic coagulants such as a sulfuric acid band and polyaluminum chloride. Among these, it is preferable to use at least one of PAM, PDADMAC, PAm, and PEI. In particular, PEI is preferable because it has a high cation density and has a high action of efficiently collecting anionic fine components, and can improve the yield of fine fibers in combination with a flocculant described later. The average molecular weight of PEI is preferably 100,000 to 2,000,000, and more preferably 200,000 to 1,000,000. If the average molecular weight is less than 100,000, anionic fine fibers cannot be sufficiently adsorbed, the yield of fine fibers is deteriorated, and foreign matter defects are increased. On the other hand, if the average molecular weight exceeds 2 million, the effects of other paper making chemicals such as paper strength agents and sizing agents are hindered. The charge density of the coagulant is preferably 15 to 20 meq / g. If the charge density is less than 15 meq / g, the yield of fine fibers is lowered, and if it exceeds 20 meq / g, the fine fibers are collected too much and the formation is lowered. The addition amount of the coagulant is preferably adjusted so that the cation requirement reduction rate and the cation requirement of the paper filtrate after addition of the cationic coagulant are satisfied. Therefore, although the addition amount of the cationic coagulant depends on the addition amount of the flocculant described later, it is 0.04% to 0.5%, more preferably 0.10% to 0% in terms of solid content with respect to the pulp. .25% is preferred. If the addition amount of the coagulant is less than 0.04%, the effect may be insufficient, while if it exceeds 0.25%, the effect of other papermaking chemicals may be hindered.

<Other chemicals>
In this embodiment, it is preferable to add a coagulant in the pulp preparation stage. In addition to the coagulant, various paper making aids such as an internal sizing agent, a fixing agent, a yield improver, a cationizing agent, a paper strength enhancer, an antifoaming agent, a colorant, and a dye may be added as necessary. In this case, it is preferably added after the addition of the coagulant so as not to inhibit the effect of the coagulant. Since the coagulant is mainly mixed in the blending chest to be a finished raw material, it is preferable to add these various papermaking aids after the blending chest.

<Flocculant (A)>
In this embodiment, after adding the cationic coagulant in the raw pulp preparation stage, the flocculant (A) containing the following polymer compound as a component is added in the first stage of the papermaking process following the raw pulp preparation stage. It is essential to do.

  The shape of the polymer compound that is a component of the flocculant (A) needs to be at least one of a mesh shape, a dendrogram shape, and a micelle shape. When the polymer compound is in these shapes, it has a high molecular weight and a large adsorption capacity for fine fibers and fillers, while it has a small floc, so that it does not break down. However, among these, it is most preferable to use a micelle shape. Micelle-like flocculants are better at adsorbing fine fibers and fillers than nets and dendrograms, but have a smaller molecular size than meshes and dendrograms, so even if the molecular weight is large, large flocs The effect of improving the yield while maintaining good formation is great, and a uniform formation is obtained. In addition, there is an effect that it can be mixed more uniformly with the pulp. Especially for papers with a high blend of 50% or more deinked pulp, it is necessary to improve the yield of fine fibers without breaking the formation, and unless both are satisfied, a paper with few foreign matter defects cannot be obtained. It was. Such an effect could not be obtained with a conventional linear flocculant, and could be achieved by using a polymer compound having a network shape, a dendrogram shape, or a micelle shape. The network shape means a shape in which molecular chains are crosslinked in a complicated state. The dendrogram means a shape in which a large number of side chains are bonded to the main chain. Furthermore, the micelle shape means a shape in which a part of the main chain is in a micelle (crystal) shape.

  As the component of the flocculant (A), those conventionally used as a yield improver can be used. Specifically, organic polymer systems such as polyacrylamide (PAM), polyvinylamine (PVAm), polydiallyldimethylammonium chloride (polydadomac, PDADMAC), polyamine (PAm), polyethyleneimine (PEI), polyethylene oxide (PEO), etc. Examples include flocculants. Among these, it is preferable to use at least one of PAM, PDADMAC, PAm, and PEI. In particular, the use of PAM having a high yield effect of fine fibers and fillers is particularly preferable because the fine fibers and fillers derived from DIP can be effectively produced.

  The average molecular weight of the flocculant (A) is 5 million to 20 million, more preferably 11 million to 17 million, and the degree of cationization is 0.5 meq / g to 5.0 meq / g, further 1.0 meq / g to It is preferably 3.0 meq / g. If the average molecular weight of the cationic flocculant is less than 5 million, the effect of the flocculant (A) may not be sufficiently exhibited, and the yield of fine fibers may be reduced. It is not preferable because it becomes large and destroys the formation. Further, if the degree of cationization is less than 0.5 meq / g, the aggregation effect may not be sufficiently exhibited, and the yield of fine fibers is reduced. On the other hand, if the degree of cationization is more than 5.0 eq / g, the floc becomes large. It is not preferable because it destroys the formation.

  Moreover, it is preferable that the addition amount of a flocculant (A) is 50 ppm-500 ppm in a pure part with respect to a pulp, Furthermore, it is preferable that they are 100 ppm-300 ppm. If the added amount is less than 50 ppm, the predetermined agglomeration effect is not sufficiently exhibited, and the yield of fine fibers may be lowered. On the other hand, if it exceeds 500 ppm, the floc becomes large and the formation is destroyed, which is not preferable.

  By adding the flocculant (A), a paper having a good texture was obtained, but the inventors further investigated and combined the flocculant (A) with another flocculant (B). It was found that the fine fibers can be sufficiently retained on the paper. That is, by reaggregating the flocs of pulp and filler aggregated with the flocculant (B) with the flocculant (A), the formation was good and the yield of fine fibers and filler could be further increased.

<Flocculant B>
In this embodiment, it is preferable to add a flocculant (B) in addition to the flocculant (A). The shape of the polymer compound that is a component of the flocculant (B) includes linear, mesh, dendrogram, micelle, etc., but the straight chain has a high ability to aggregate more pulp and filler. The shape is preferred.

  Examples of the component of the flocculant (B) include those conventionally used as a yield improver. Specifically, organic polymer systems such as polyacrylamide (PAM), polyvinylamine (PVAm), polydiallyldimethylammonium chloride (polydadomac, PDADMAC), polyamine (PAm), polyethyleneimine (PEI), polyethylene oxide (PEO), etc. Examples include flocculants. Among these, it is preferable to use at least one of PAM, PDADMAC, PAm, and PEI. In particular, it is preferable to use a PAM capable of forming a large floc in order to improve the yield of fine fibers and filler.

  The average molecular weight of the flocculant (B) is 5 million to 20 million, more preferably 9 million to 15 million, and the degree of cationization is 0.5 meq / g to 5 meq / g, further 1.0 meq / g to 2. It is preferably 5 meq / g. If the average molecular weight of the cationic flocculant is less than 5,000,000, the effect of the flocculant (B) may not be sufficiently exhibited, and the yield of fine fibers may be deteriorated. It is not preferable because it becomes large and destroys the formation. On the other hand, if the degree of cationization is less than 0.5 meq / g, the agglomeration effect is not sufficiently exhibited, and the yield of fine fibers may be deteriorated. It is not preferable because the effect is large and the pulp is agglomerated too much to break the formation.

  Moreover, it is preferable that the addition amount of a flocculant (B) is 10 ppm-200 ppm in a pure part with respect to a pulp, Furthermore, it is preferable that they are 20 ppm-100 ppm. If the addition amount is less than 10 ppm, the predetermined agglomeration effect may not be sufficiently exhibited, and the yield of fine fibers may be reduced. On the other hand, if it exceeds 200 ppm, the pulp agglomeration effect is large, and the pulp is excessively agglomerated. This is not preferable because it breaks the match.

  In particular, in paper with a high blend of 50% or more deinked pulp, the yield of fine fibers derived from deinked pulp can be obtained by combining the flocculant (A) and flocculant (B) without breaking the formation. Can be improved and foreign matter defects can be reduced, which is preferable. In the method using only the linear flocculant (B) without using the flocculant (A), the floc becomes too large to break up the formation, and the method using only the flocculant (A). Then, since the yield of fine fibers is poor and it is difficult to prevent the occurrence of defects, it is not preferable.

  Conversely, when the deinked pulp is less than 50%, the flocculant (A) and the flocculant (B) are combined to reduce the number of fine fibers. Tends to increase, which is not preferable because the formation is lowered.

  In order to maximize the synergistic effect of the flocculant (A) and the flocculant (B), it is preferable to add the flocculant (A) before the screen and the flocculant (B) after the screen. This is because, after obtaining a large floc with the flocculant (A), once the floc is disassembled with the share of the screen and the floc is re-formed with the flocculant (B), the floc is formed to the extent that the formation does not deteriorate. This is because the yield of fine fibers can be improved to the maximum while suppressing the above.

[Paper making process]
The papermaking equipment that can be used in the present invention is not particularly limited. To improve the yield of fine fibers, which is the object of the present invention, a wire part made of a gap former, a press made of a straight-through type without an open draw. It is preferable to combine a dryer part consisting of a part and a single deck dryer. The reason is as follows.

<Wire part (head box)>
The adjusted pulp slurry is sent to the wire part via the head box. The wire part is not particularly limited, such as a long-form former, a combination of a long-form former and an on-top former, or a twin wire former, but the paper jet ejected from the head box is immediately sandwiched between two wires. Gap type gap formers are preferable because there is little difference between the front and back because they dehydrate from both sides, and the difference between front and back is less likely to occur.

<Press part>
The paper layer in the wire part is transferred to the press part and further dewatered. The press machine can be either a straight-through type, an invar type, or a reverse type, and a combination of these can also be used, but the straight-through type with no open draw is easy to hold the paper, This is preferable because there are few operational troubles such as paper breaks. As the dewatering method, a conventional method such as a suction roll method or a grooved press method can be used. However, since the shoe press has high dewaterability, the linear pressure applied to the paper can be reduced and the strength is weak. This is preferable because the strength of coated paper produced from deinked pulp is unlikely to decrease.

<Pre-dryer part>
The wet paper that has passed through the press part is transferred to a single-deck pre-dryer part and dried. The pre-dryer part is preferably a no-open draw type single-deck dryer that has few paper breaks and can be dried efficiently without reducing the bulk. A drying method using a double deck method is also possible, but it is not preferable because it is inferior to a single deck method in terms of operability such as canvas marks, paper breaks, wrinkles, and paper splicing.

[Undercoating]
For the purpose of improving the rigidity, the above base paper can be coated with a water-soluble polymer using a roll coater.

  Examples of water-soluble polymers include starches such as oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch and raw starch or derivatives thereof, synthetic polymers such as polyacrylamide and polyvinyl alcohol, and water resistance and surface strength improvement. The paper strength enhancing agent described above, the externally added sizing agent for the purpose of imparting sizing properties, or those commonly used as surface treatment agents can be used alone or in combination. Of these, oxidized starch is preferable because it can improve the workability while minimizing the decrease in whiteness while improving the rigidity.

Coating amount in the case of using the oxidized starch as a water-soluble polymer is not particularly limited, preferably 0.1~1.5g per side / m ^2, more preferably 0.2~1.3g / m ^2, most preferably from 0.3 to 1.0 g / m ^2. If it is less than 0.1 g / m ² , the coverage is poor and the effect of improving the stiffness of the base paper is small. If it exceeds 1.5 g / m ² , the stiffness will improve, but the original color of starch will tend to appear on the coated paper, and not only will the whiteness decrease, but the coating liquid will increase and the coating will start from the roll surface. Since the liquid is scattered, coating mist is generated, and defects and foreign matters are easily generated, and workability is deteriorated.

  Such a water-soluble polymer can be applied to, for example, a two-roll size press coater, a gate roll coater, a blade metering size press coater, a rod metering size press coater, or a film transfer type roll coater such as a shim sizer or a JF sizer. Can be applied by machine tool. A film transfer type roll coater is preferable because it has a high surface coverage and can prevent a decrease in printability due to dropping of fine fibers. Coating machines other than those described above, such as blade coaters and air knife coaters, are unfavorable because the coatability is poor at low coating amounts and non-coated parts are likely to occur, and uniform coating is required for spray coaters and curtain coaters. Is not obtained, and it is difficult to prevent the fine fibers from falling off.

[Flatening treatment (pre-calendar)]
The base paper after the undercoating is preferably subjected to a flattening process using a precalender before the topcoating (pigment coating). As the pre-calender, a soft calender having a metal roll on the upper side and an elastic roll on the lower side is preferable because of its high surface improvement. The pre-calendar can be performed in one stage or a combination of two or more stages as required. The surface of the base paper after the application of the water-soluble polymer is flattened by the pre-calender treatment, and the base paper is not reduced by reducing the strength of the paper by not requiring excessive flattening treatment on the later calendar. The flatness of the surface can be improved, and sufficient printability and paper strength as a coated paper can be obtained. Further, the surface of the base paper is flattened to improve the coating property of the top coating, to suppress the generation of mist, and to suppress the coating unevenness of the coating liquid. The linear pressure of the pre-calender is preferably 10 to 80 KN / m, more preferably 10 to 50 KN / m. If it is less than 10 KN / m, flattening of the base paper after application of the water-soluble polymer will not proceed, and if it exceeds 80 KN / m, the base paper will be compressed more than necessary, and the paper strength will be reduced. .

[Top coating (pigment coating)]
Next, a coating layer containing a pigment and an adhesive is applied to one or both sides of the base paper to provide a coating layer. Conventional pigments can be used, such as kaolin, fine kaolin, calcium carbonate, talc, satin white, calcium sulfite, gypsum, barium sulfate, white carbon, calcined kaolin, structured kaolin, diatomaceous earth, magnesium carbonate, Inorganic pigments such as titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, magnesium oxide, bentonite, sericite, polystyrene resin fine particles, urea formalin resin fine particles, fine hollow particles, porous One or more of organic pigments such as fine particles may be appropriately selected and blended. Among them, calcium carbonate having a large whiteness improving effect and clay having a high white paper gloss improving effect are preferable.

  There are no particular limitations on the type of adhesive blended in the coating solution together with the above pigments, for example, proteins such as casein and soybean protein; styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, Conjugated diene latex such as styrene-methyl methacrylate-butadiene copolymer latex, acrylic latex such as polymer latex or copolymer latex of acrylate ester and / or methacrylate ester, ethylene-vinyl acetate polymer latex, etc. Vinyl-based latex, or latexes such as alkali partially soluble or insoluble latex obtained by modifying these various copolymer latexes with a functional group-containing monomer such as a carboxyl group; polyvinyl alcohol, olefin-maleic anhydride resin , Me Synthetic resin adhesives such as min resin, urea resin, urethane resin; starches such as oxidized starch, positive starch, esterified starch, dextrin; cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, etc. Adhesives used for paper can be mentioned, and one or two or more of these can be appropriately selected and used.

  Although there is no limitation in particular in the ratio of the pigment in a coating agent, and an adhesive agent, Preferably an adhesive agent is 3-17 mass parts by solid content ratio with respect to 100 mass parts of pigments, More preferably, it is 5-15. Part by mass. If the amount of the adhesive is less than 3 parts by mass, the strength of the coating layer is lowered, and the coating layer is easily taken up by the printing ink at the time of printing, so that it is easy to cause troubles that are not printed (white spots). . On the other hand, if it exceeds 17 parts by mass, the effect of improving the surface strength reaches its peak and the economic efficiency deteriorates.

  Furthermore, for example, various commonly used auxiliaries such as a fluorescent brightening agent, a fluorescent brightening agent fixing agent, an antifoaming agent, a release agent, a coloring agent, and a water retention agent are appropriately blended in the coating liquid. You can also.

  The coating of the top coat layer (pigment coating layer) on the base paper is preferably performed, for example, in a coater part between dryer parts which is performed in a plurality of stages, usually two stages of a pre-dryer part and an after-dryer part. . In this coater part, as in the case of undercoat coating, for example, a film transfer type roll such as a 2-roll size press coater, a gate roll coater, a blade metering size press coater, a rod metering size press coater, or a shim sizer or JF sizer. It can apply | coat with coating machines, such as a coater. The film transfer type roll coater is preferable because it has a high surface coverage even at a low coating amount and a coated paper having a high surface strength can be easily obtained. Coating machines other than the above, such as blade coaters and air knife coaters, are not preferred because they cannot be applied at low coating amounts, and spray coaters and curtain coaters can be applied at low coating amounts but are uniform. Since a coated surface cannot be obtained, surface coverage and surface strength tend to be low, which is not preferable.

  In addition, when using an on-machine coater that is integrated with the paper machine, the coating device can produce products in a shorter time than an off-machine coater, so that moisture unevenness in the width direction and flow direction can be reduced. It is preferable because a more uniform coating can be obtained and a uniform surface strength can be obtained. In addition, as a drying method in the dryer part, for example, various heating drying methods such as hot air heating, gas heater heating, and infrared heater heating can be appropriately employed.

The coating amount of the coating liquid into the base paper is per side, preferably ^{3g / m 2 ~10g / m 2} , more preferably ^{5g / m 2 ~9g / m 2} . If the amount of the coating liquid is less than 3 g / m ² per side, an uncoated part is likely to occur on the paper surface, and a part having a low surface strength may be generated. If the coating exceeds 10 g / m ² per side, cracks are likely to occur in the coating layer, and not only the printability but also the cosmetic properties of the coated paper itself are not preferred.

[Calendar part]
For the purpose of imparting glossiness, flatness, and printability to the coating layer, a pair of rolls, at least one of which is a hot roll, preferably a paper is passed between an elastic roll and a metal roll to perform a flattening treatment. it can. The linear pressure of the calendar is preferably 100 to 600 KN / m, and more preferably 100 to 400 KN / m. If it is less than 100 KN / m, the pigment coating layer will not be flattened, and if it exceeds 600 KN / m, the paper will be pressed more than necessary, and the paper strength will be reduced. 100-300 degreeC is preferable and the temperature of a metal roll has more preferable 100-200 degreeC. If the temperature is less than 100 ° C, the pigment coating layer does not flatten. If the temperature exceeds 300 ° C, fiber burns may occur or the coated paper itself may turn yellow due to heat and pressure. Is not preferable.

  As the calendar facility, a flattening facility such as a super calendar or a soft calendar can be used. Among them, a multi-nip calender, more preferably a 6-, 8-, or 10-stage multi-nip calender is optimal because it is easy to adjust the nip pressure and the rigidity and white paper gloss. Moreover, as an installation place of a calendar, an on-machine type integrated with a paper machine and a coating machine is preferable. With the on-machine type, flattening can be performed immediately after coating with a high paper surface temperature, making it easier to improve the glossiness of blank paper, lowering the linear pressure required to obtain the desired coated paper, and reducing paper strength. Is preferable because of a small amount.

  Next, the case where the paper of the present invention is a coated paper will be described in more detail based on examples, but the present invention is not limited to these examples.

[Examples and Comparative Examples]
First, as raw material pulp, MDIP produced from LBKP, NBKP and magazine waste paper was mixed at a ratio (mass ratio) shown in Table 1, and each 100 parts by mass (absolutely dry amount) of this pulp was mixed with light carbonic acid. Calcium (product number: TP-121-6S, manufactured by Okutama Kogyo Co., Ltd.) 5%, cationized starch (product number: Amilofax T-2600, manufactured by Abebe Japan Co., Ltd.) 1%, and a coagulant and a flocculant ( A) and a flocculant (B) were added in the formulation shown in Table 1 to obtain a pulp slurry. The types of coagulant and flocculant are as follows.

<Coagulant>
・ Polyethyleneimine (product number: Himax SC-924, manufactured by Hymo Co., Ltd.)
・ Dimethyl methacrylate (product number: RX2100, manufactured by Hymo Co., Ltd.)
・ Polyamine (Part No .: Cartafix NTC2, manufactured by Clariant Japan Co., Ltd.)
<Aggregating agent (A) and aggregating agent (B)>
・ Linear polyacrylamide (Product No .: Polymin 470, manufactured by BASF Corporation)
・ Linear polyethyleneimine (product number: Cassiofast VFH, manufactured by BASF Corporation)
・ Linear polyamine (Product No .: PL2615H, manufactured by Eka Chemicals Co., Ltd.)
-Micellar polyacrylamide (product number: Hymo Lock ND-270, manufactured by Hymo Co., Ltd.)
・ Reticulated polyacrylamide (prototype)
・ Diamorphic polyacrylamide (prototype)
・ Micellar polyethyleneimine (prototype)
・ Micellar polyamine (prototype)

Next, after a paper web was manufactured through a wire part, a press part, and a pre-dryer part, a starch coating solution was applied on both sides with a coating amount of 0.5 g / m ² per side. After this undercoating, the film was dried by an after dryer part and flattened by a pre-calender part at a linear pressure of 100 kN / m. Next, in the coater part, 30 parts by mass of fine kaolin clay (product number: AMAZON, manufactured by Kadam) as a pigment, 70 parts by mass of wet heavy calcium carbonate (product number: ESCALON # 90, manufactured by Sankyo Flour Milling Co., Ltd.), adhesive As a coating liquid containing 10 parts by mass of styrene-butadiene latex (Part No .: PA5036, manufactured by Nippon A & L Co., Ltd.), both sides of the base paper were coated so that the coating amount was 8.0 g / m ² . . Next, the base paper with the coating layer formed on both sides was used in an after dryer part to dry the coating layer, and the calendar part was subjected to planarization treatment at a linear pressure of 150 kN / m and a temperature of 200 ° C. Then, it was used for the reel part and the winder part to obtain coated paper.

  Paper was made using a gap former for the wire part, a straight-through type without an open draw for the press part, and a single deck dryer for the dryer part. In the coater part, after undercoating with a film transfer type roll coater, it was flattened with a pre-calender and overcoated with a film transfer type roll coater. In the calendar part, a flattening process was performed using a multi-nip calendar.

The weight of the coated paper obtained was 105 g / m ^{2 as} measured according to JIS P 8124. The coated paper was evaluated as follows. The results are shown in Table 1.

(A) Fine fiber content rate The coated paper was disaggregated according to the method described in JIS P 8220 "Pulp-Disaggregation method", and the proportion of fine fibers having a fiber length of 0.2 mm or less contained in all fibers was measured. The measurement was performed using a fiber length measuring tester (model number: FiberLab, manufactured by Metso), and the cut-off was set at 0.02 mm.

(B) Contaminant area ratio Contaminant measuring device (manufactured by ESK Create Co., Ltd., scanner: EPSON ES-2000, optical resolution: 1600 DPI, cut-off: 0.001 mm ² , measurement area: A4 size, threshold setting range: black and white 256 steps, threshold value: 75 steps from the black portion of the 256 steps as impurities, and the coated paper was measured.

(C) Geometric index A sheet formation tester (model number: SHEET FORMATION TESTER, manufactured by Toyo Seiki Seisakusho), a scanning beam is measured with a He-Ne gas laser (1 mW, beam diameter of about 0.2 mm), and a scanning frequency of 5.88 Hz. The total change rate (%) obtained was defined as the formation index.

Since all the coated papers of the examples are highly blended with deinked pulp, the coated paper has a fiber length of 0.2 mm or less and a fiber length of 10% or more, and contains a large amount of fine fibers. This is a coated paper having a good formation with a ratio of 0.5 mm ² / m ² or less and few defects and a formation index of the sheet formation tester of 10 or less.

  On the other hand, the coated paper of the comparative example does not use the predetermined flocculant or coagulant as in the example or does not use deinked pulp, so the fine fiber content, the area of impurities Coated paper with bad rate or formation index.

  The paper of the present invention is highly blended with deinked pulp, has few foreign matter defects and has a good texture, has low environmental impact, is resource-saving, and has a high-class feel and high cosmetics while reducing costs. For example, it can be suitably used for commercial printing of flyers, magazines, pamphlets and the like.

Claims (4)

  A paper comprising a polymer compound (flocculating agent A) having at least one of a mesh shape, a dendrogram shape, and a micelle shape, and having a formation index measured by a sheet formation tester of 10 or less. The paper according to claim 1, comprising 50% by mass or more of deinked pulp and having a foreign matter area ratio of 1.8 mm ² / m ² or less.   The paper according to claim 1 or 2, comprising a linear polymer compound (flocculating agent B).   To a pulp slurry containing 50% by mass or more of deinked pulp, a polymer compound (flocculating agent A) having at least one of a mesh shape, a dendrogram shape, and a micelle shape and a linear polymer compound (flocculating agent B) ) Are included in this order.