JP4629410B2 - Production method of coated base paper - Google Patents

Description

  The present invention relates to a method for producing a coated base paper.

A large amount of paper sludge such as deinking floss, drainage and dewatered sludge is generated from the paper manufacturing process, but in order to make effective use of the landfill, this paper sludge is conventionally burned and its volume reduced. Yes. However, since the papermaking sludge contains a large amount of inorganic substances, a large amount of combustion ash (inorganic substances) remains even when burned, and the effect of volume reduction is low. Therefore, efforts have been made to use this combustion ash as a raw material for cement and as a soil conditioner. However, these methods do not require a large amount of inorganic substances, so in the end, most of the combustion ash is It will be landfilled.
As a method for effectively using the combustion ash, it may be used as an internal paper filler or a coating pigment. However, since the whiteness of the combustion ash is low, the internal paper filler or coating is used as it is. It is not suitable for use as a pigment. Further, when the recovered recycled filler is used, there is a problem that most of the filler having a small particle diameter flows out into the white water at the time of paper making and the retention in the paper layer is very bad. In addition, the filler particles are distributed between the fibers, thereby inhibiting the bonding between the fibers and reducing the paper strength / stiffness. Further, when an inorganic substance recovered from papermaking sludge combusted at a high temperature is used as an internal filler, there has been a problem that the papermaking wire and the like are severely worn.

Therefore, the present applicant previously proposed a method for producing a reclaimed filler that has a high whiteness and does not cause wear of paper-making wires or the like by aligning the shape of the paper-making sludge during combustion to a certain size. (See Patent Document 1).
JP 2002-275785 A

  However, even when coated base paper is produced using such recycled filler, there remains a problem that the yield of the filler is low and the rigidity of the resulting paper is low.

  The present invention has been made in view of such circumstances, and provides a method for producing a coated base paper having a high yield and a high rigidity (bending rigidity) of the filler by using the recycled filler recovered from the papermaking sludge. The purpose is to do.

Method for producing a coating base paper of the present invention, (1) the collected reproduction filler from paper sludge, in paper stock preparation step of adding 5-30 wt% per bone dry pulp to between species box inlet line Control the amount of cationic coagulant added to the papermaking raw material slurry and / or measure the freeness in the supply process from the seed box to the wire part based on the cation demand measurement value of the cation demand measurement apparatus of in step to control the amount of coagulant and flocculant by freeness measurements, using (2) twin wire method, in the forming zone to form a paper layer before initial dewatering by a roll suction and / or suction blade step, and (3) elastic roll and flattening process hand combination comprising comprising at least one of a metal roll At, treating flattening the coating base paper surface, viewed including the ash was measured in accordance with JIS P 8128 is characterized in that 16 to 20%.

The method of producing coating base paper of the present invention, since the addition of 5 to 30 wt% per bone dry pulp material between the inlet regeneration filler prepared in the process from the seed box, easily filler is dispersed, and the coating In the forming zone in step (2) of the manufacturing method of the base paper, by performing initial dehydration with a roll suction and / or a suction blade, the loss of the filler from the slurry is reduced, and the yield of the filler is improved. The rigidity of the base paper is improved by flattening the coated base paper surface with a flattening processing means including at least one combination of an elastic roll and a metal roll.

Furthermore, in the papermaking raw material preparation step of the manufacturing method of the coated base paper, the amount of the cationic coagulant added to the papermaking raw material slurry is controlled based on the cation demand measurement value by an online cation demand measurement device, and / or By measuring the freeness in the supply process from the seed box to the wire part and controlling the addition amount of the coagulant and the flocculant by the freeness measurement value in the supply process, it is possible to control the electric potential by the optimum cation demand, It is possible to stabilize the drainage at the wire part of the paper machine and reduce paper breakage at the wet part. Furthermore, by adding a cationic coagulant to an anionic substance and adding an anionic (or cationic) coagulant to the coagulated substance, the coagulated anionic substance aggregates to form a floc. The pitch density can be reduced, dirt, defects, and paper breaks can be reduced, and productivity can be improved. Moreover, the yield can be improved by neutralization with an anionic substance, and when the anionic substance aggregates and forms a floc, the drainage state becomes good.

  According to the present invention, it is possible to produce a coated base paper having a high yield and a high rigidity by using the recycled filler recovered from the papermaking sludge.

Next, an embodiment of a method for manufacturing a coated base paper of the present invention (hereinafter also simply referred to as a manufacturing method) will be described in detail.
First, in the production method of the present invention, as a filler, (1) a molding step of molding paper sludge into a shape having a cross-sectional area of 710 mm ² or less and a length of 30 mm or less, (2) a molded product obtained by molding is reduced in oxygen A step of indirectly heating and carbonizing at a temperature of less than 600 ° C. under conditions, (3) a combustion step of burning carbide obtained by carbonization at a combustion temperature of 600 to 800 ° C., and (4) combustion ash obtained by combustion. A regenerated filler produced by a pulverizing step for pulverizing the particles to have an average particle size of 0.1 to 10 μm is added in an amount of 5 to 30% by weight per the absolutely dry pulp raw material.
When the recycled filler produced by the above process is used, the whiteness and smoothness of the resulting paper are high, and the papermaking wire or the like is not worn during the papermaking. The blending amount of the regenerated filler is 5 to 30% by weight, preferably 15 to 25% by weight, based on the absolutely dry pulp raw material. If it is less than 5% by weight, the film-forming property of the coating liquid on the surface of the base paper will be poor, and the problem that fine irregularities will be generated on the surface of the coating layer tends to be manifested. This is not preferable because the reduction appears remarkably and the problem of lowering the stiffness of the base paper occurs. Any method may be used for producing the regenerated filler as long as the above conditions are satisfied. For example, it can be suitably produced according to Patent Document 1 described above. Specifically, for example, paper sludge is dehydrated, kneaded with a kneader, extruded with an extruder, and then cut into lengths and molded. The obtained molding is carbonized by indirect heating in a carbonization furnace under low oxygen conditions. The obtained carbide is burned in a combustion furnace (for example, a rotary kiln) by a method in which a flame is not directly blown. The obtained combustion ash is pulverized by a dry pulverizer (for example, a roll crusher), a wet pulverizer (for example, a wet mill) or the like. And it classifies and manufactures combustion ash with a particle diameter of 10 micrometers or less with a classifier.
Examples of pulp raw materials that can be used include mechanical pulp (GP, CGP, RGP, PGW, TMP, etc.), chemical pulp (NBKP, LBKP, etc.), waste paper pulp (DIP, etc.), deinked pulp, etc. These pulps can be used alone or mixed at any ratio.

By forming the papermaking sludge in advance, carbonization and combustion can be performed uniformly, and combustion ash with high whiteness and appropriate hardness can be obtained. The cross-sectional shape of the molded product may be any shape, such as a circular shape, an elliptical shape, a polyhedral shape such as a triangle, or a star shape, and may be appropriately selected so that the cross-sectional area is in the range of 9.6 to 710 mm ² . When the cross-sectional area exceeds 710 mm ² , carbonization to the core cannot be performed in the carbonization process. The length is preferably 30 mm or less, more preferably 15 mm or less, and even more preferably 8 to 10 mm. If the length exceeds 30 mm, the molded product will collapse in the carbonization step, which is not preferable.
The carbonization step is performed under low oxygen conditions, preferably under oxygen-free conditions. Since the self-heating of the molded product is used, less fuel is required compared to combustion performed in the presence of oxygen, and heat is quickly and reliably transmitted to the inside. The heating temperature is less than 600 ° C., preferably less than 500 ° C., and uniform hardness makes the hardness and whiteness uniform.
The combustion process is performed at a combustion temperature of 600 to 800 ° C, preferably 650 to 750 ° C. If the combustion temperature is less than 600 ° C., the combustion may be incomplete and the whiteness may be reduced. On the other hand, if it exceeds 800 ° C., there is a risk of excessive combustion and increased hardness. The burning time is not particularly limited, but is usually 2 to 4 hours, preferably 2.5 to 3.5 hours.
The pulverization step may be any pulverization method as long as the average particle size is 0.1 to 10 μm, but it is easy to obtain a regenerated filler having a uniform particle size distribution by adjusting the particle size step by step, so that coarse pulverization is dry-type. In the pulverization, it is preferable to adjust the particle size by wet pulverization. The average particle diameter is preferably 0.1 to 10 μm. When the average particle size is less than 0.1 μm, it takes time and energy to adjust the particle size, and the yield of recycled filler in the papermaking stage is deteriorated. On the other hand, if it exceeds 10 μm, wire wear at the paper making stage, abrasion of rolls, and blade wear in cutter processing after papermaking are not preferable.

  The regeneration filler is added between the seed box and the inlet. By adding in the meantime, the regenerated filler becomes easy to disperse and the fixing property to the fibers is improved. As a result, the yield of filler is improved. Further, since the recycled filler does not hinder the bonding between the fibers, the stiffness of the base paper does not decrease. In a more preferable addition place, it is preferable to add it in the vicinity of the inlet as much as possible in order to reduce the chance that the recycled filler is discharged out of the system as a reject.

In the papermaking raw material preparation process, the slurry of the papermaking raw material is controlled based on the cation demand measured value by the online cation demand measuring device, and the addition amount of the cation coagulant is controlled and / or the freeness in the process of supplying from the seed box to the wire part It is preferable to control the addition amount of the coagulant and the flocculant by the freeness measurement value in the supply process.
Recycled fillers, in particular, have a tendency to increase cation demand because they contain various inorganic components, unlike fillers with almost uniform ingredients, and the behavior of cation demand is larger than conventional filler addition, and the measurement of cation demand Control of the amount added depending on the result is considered to be a necessary means for preventing contamination in the papermaking system and stabilizing the operation in addition to the effect of improving the yield of the filler.

  According to this papermaking raw material preparation method, the amount of cationic coagulant added can be controlled on-line, so that potential control by optimum cation demand is possible, and in particular, rapid cation demand measurement values are fed back. It is possible to control this, and it is possible to stabilize drainage at the wire part of the paper machine and to reduce paper breakage at the wet part. In addition to controlling the addition amount of coagulant and flocculant by the freeness measurement value during the supply process from the seed box to the wire part, the potential control by the cation demand is performed by controlling the addition amount of the cationic coagulant. Potential control by cation demand is possible.

  In this specification, “cation demand” refers to the total charge of an anionic substance. An anionic substance (anionic trash) is a negatively charged substance, including pulp (including fine fibers), filler (recycled filler, calcium carbonate, talc, etc.), various wet end additive chemicals (pigments, Sizing agent, antifoaming agent, etc.), resin pitch, elution lignin, etc.

  By adding a cationic coagulant to the anionic substance and adding the anionic (or cationic) flocculant to the coagulated substance, the coagulated anionic substance aggregates to form a floc. Under such a mechanism, the pitch can be adsorbed to the pulp and passed through the process together with the paper stock in a minimal state, or discharged out of the system, and the pitch concentration can be reduced. As a result, dirt, defects and paper breaks can be reduced, and productivity can be improved. The yield can be improved by neutralization with an anionic substance. When the anionic substance aggregates and forms floc, the drainage state becomes good.

For this reason, the cation demand (or amount thereof) is required to be low with respect to the drainage state.
On the other hand, the cation demand varies depending on the type of blended raw material (for example, NBKP, LBKP, DIP, GP, coat broke). In addition, it includes variations over time, and therefore, it is important to control the amount of the cationic coagulant to be added depending on the type of raw material.

The control of the addition amount of the cationic coagulant and the control of the addition amounts of the coagulant and the flocculant will be described in more detail with reference to the drawings.
FIG. 1 is a schematic diagram of an example in which coat broke 1 and GP (grand pulp) 2 are used as blending raw materials of strong anion factors. Coat broke 1 mixes raw materials by broke chest 3 and leads to blended chest 4. GP2 is led directly to the blending chest 4. The blended raw material of the blended chest 4 is supplied to the machine chest 5 and then guided to the seed box 6. The machine raw material adjusted here is stored in the stock through the primary pump 8B, the cleaner 7, the secondary pump 8A and the screen 9. It is supplied to the machine part 12 of the paper machine 11 by the inlet 10.

For coat broke 1, in the process leading from broke chest 3 to compounding chest 4, the amount of broke coagulant added by broke demand control device 20B is controlled based on the cation demand measurement value by online cation demand measurement device 20A. To do.
For GP2, in the process of leading from blending chest 4 to machine chest 5, the amount of GP coagulant added by GP demand control device 30B is controlled based on the cation demand measurement value by online cation demand measurement device 30A. .
As the addition control operation of the coagulant, for example, the cation demand value of the coat broke 1 is measured by the cation demand measuring device 20A, and then the cation demand value measured by the demand control device for broke and the preset target cation demand. Calculate the difference from the value. The target cation demand value is set by experimentally obtaining in advance a cation demand value that can ensure the yield of the coating broke filler. Next, the increase / decrease amount of the addition amount of the broke coagulant is calculated according to a predetermined arithmetic expression according to the difference between the measured value and the target value. Note that the calculation may be made with reference to a table stored in the memory instead of the calculation based on the calculation formula. Next, for example, an opening degree adjustment command is output to the addition adjustment valve so that the addition amount of the broke coagulant obtained by the calculation is obtained.

  In this case, when there are a plurality of machine chests 5, the cation demand measurement value is obtained for the raw slurry between the machine chests 5 by an online cation demand measurement device, and the addition amount of the cation coagulant is set between the machine chests 5. Although it is possible to control, when cationized starch is added to the first machine chest 5, the phenomenon that anion trash and cationized starch condense first occurs, and paper strength is improved by adding cationized starch. However, as shown in the former (shown), in the process of leading from the compounding chest 4 to the machine chest 5, the addition amount of the cationic coagulant is determined based on the cation demand measurement value by the online cation demand measurement device 30A. If added in a controlled manner, the addition of a cationic coagulant will block the anionic trash. Runode preferred for cationic starch can be easily coupled to the pulp.

When adding other pulp to the blended chest 4, for example, when adding KP, DIP and machine broke as shown in the figure, control the amount of coagulant added by measuring these cation demands. However, it is usually sufficient to control the addition amount of the cation coagulant based on the cation demand measurement value by the cation demand measurement device 30A.
In addition, although it is desirable to automate the addition amount control of the cationic coagulant, it does not exclude an aspect in which the worker manually adjusts the addition amount based on the actual measurement value indicated by the cation demand measuring device.

  PCT15 or PCT20 (trade name, cation demand measuring device manufactured by Mutek) is a typical example of an online cation demand measuring device. In this cation demand measuring device, the stock is introduced into the cell of the test machine, the flow of the sample liquid is generated between the cell cylinder and the piston by the operation of the upper and lower pistons, and the surface charge of the colloidal particles is distorted. It is configured to generate electricity, and the charge requirement is measured by polyelectrolyte measurement by utilizing the fact that colloidal dissolved substance particles in the pulp suspension are charged with ions. It is a thing.

  Examples of the cationic coagulant include PAM (polyacrylamide), PDADMAC (polydadomac), PAm (polyamine), PEI (polyethyleneimine) and the like.

Further, in the supply process from the seed box 6 to the wire part 12, the inlet raw material, in particular more collected inlet raw material harvested line in the stock inlet 10, continuously or intermittently measuring the freeness value by freeness measuring machine 13 Then, the processing unit 14 uses the measured value as an apparent inlet freeness value, which is used as an index having a correlation with the freeness, and based on the apparent inlet freeness value, the coagulant and agglomeration in the preparation process of the papermaking raw material Control the amount of agent added to stabilize the freeness.

  In the present embodiment, after the machine raw material from the seed box 6 passes through the cleaner 7, a coagulant is added in front of the screen 9 after the secondary pump 8 </ b> A, and a flocculant is added after passing through the screen 9. I am doing so.

The following can be used as a freeness measuring machine. That is, a predetermined amount (for example, 200 cc) of the pulp liquid in the inlet raw material is sampled and diluted with dilution water, preferably 0.07 to 0.13%. To do. A mat (hard mat) is formed at the lower part of the screen with this low-concentration pulp liquid. Thereafter, the amount of drainage of the inlet raw material passing through the mat (hard mat) is measured, and the obtained freeness value is defined as the above-mentioned “apparent inlet freeness value”. Although there is no limitation on the measurement of the drainage amount itself, the height of the filtrate collected in the measurement tube is measured by back pressure measurement using a bubbler tube or the like. As a specific example of the freeness measuring machine, “Pulp freeness measuring instrument Neo Freene NF-200A” manufactured by Koei Kogyo Co., Ltd. can be mentioned.
The apparent inlet freeness value greatly correlates with the first pass retention (FP), the apparent press dewatering value (inlet drainage value), the white water concentration, and the draw value. Therefore, there is a great significance to control based on the apparent inlet freeness value.

The addition amount of the coagulant and the flocculant can be controlled by any of the following methods (1) to (3).
(1) The addition amount of the coagulant and the coagulant is increased or decreased proportionally.
(2) Fix the addition amount of the coagulant and adjust the addition amount of the flocculant.
(3) Fix the addition amount of the flocculant and adjust the addition amount of the coagulant.

Examples of the coagulant include the same anionic coagulants as described above.
For the flocculant, it is necessary to select a cationic or anionic flocculant depending on the state of the system (before the machine: the machine chest exit side to the inlet). Examples of cationic flocculants include cationic polyamine resins, cationic polyamine polyamide resins, cationic polyacrylamides, cationic modified starches, styrene acrylic resins, cationic thermosetting resins, inorganic aluminum compounds such as aluminum sulfate, and the like. be able to. Examples of the cationic flocculant include anionic acrylamide and anion-modified starch.
Here, the coagulant is preferably added to at least one of the slurry adjustment process of the papermaking raw material or the supply process from the seed box to the wire part. As a more preferable addition method, different kinds of coagulants may be used in combination.

  The obtained papermaking raw material is formed into a paper layer by a twin wire system (a system in which papermaking material is discharged between two wires forming a loop). Forming a paper layer with the twin-wire method is preferable because it can produce high-quality paper with little difference between the front and back sides, but other paper machines (round net type, long net type, short net type, etc.) ) To form a paper layer.

  When making paper, it is preferable to perform initial dehydration with a roll suction and / or a suction blade in the forming zone. The yield of the filler can be increased by dehydrating gently first and then dehydrating afterwards. A combination of a roll suction and a suction blade is preferable, but it is particularly preferable to dehydrate in the order of the roll suction and the suction blade.

Further, the surface of the coated base paper is flattened by a flattening processing means including at least one combination of an elastic roll and a metal roll. As an example of the flattening processing means comprising an elastic roll and a metal roll, a thermal soft calender can be cited. This thermal soft calender is usually used to heat a metal roll to 100 ° C. or higher and pressurize the paper surface to smooth the paper surface. If this thermal soft calender is used, a conventional super calender is used. High surface smoothness and printing gloss can be obtained with a small number of nips (about 2 to 4 nips compared to 10 to 14 for conventional supercalenders), and the product rigidity is relatively It has the advantage that it can be maintained at a high value.
The smoothing process in the soft calender is such that the surface of the paper is brought into surface contact with the metal roll and the elastic roll at a high temperature while passing through the nip formed by the heated metal roll and the elastic roll. Can be instantly flattened, so that the inner base paper layer can be kept relatively bulky with a small number of nips.

The number of nips of the thermal soft calender is preferably at least 2 nips for obtaining high surface smoothness and printing gloss. However, if the number of stacks composed of a combination of a metal roll and an elastic roll of the soft calender becomes too large, Since space is required, the temperature load on the paper becomes too large, yellowing is likely to occur, and excess equipment is required.
The metal roll can be heated, for example, by circulating hot water or oil inside the metal roll. However, since the surface temperature in the width direction of the roll can be controlled with high accuracy, an electromagnetic induction effect is used. It is preferable to carry out with an internal heating device capable of controlling the temperature in the roll width direction. By using such an internal heating device, a desired difference can be given to the temperature in the axial direction of the roll, the deformation of the roll itself can be prevented, and the smoothness of the light wrapping paper in the roll axial direction can be kept constant. As an example of the metal roll provided with such an internal heating device, a jacket roll (registered trademark) manufactured by Tokuden Corporation can be exemplified. The surface temperature of the metal roll is preferably set to 100 ° C. or higher, more preferably 130 ° C. or higher in order to make only the surface smooth while maintaining the bulkiness of the paper, and it is preferable to perform the planarization treatment in this state. However, if the surface temperature is too high, yellowing of the paper is likely to occur. Therefore, auxiliary cooling equipment such as a cooling roll is usually provided as a method for preventing the temperature from rising excessively.

  As the metal roll, for example, a chilled roll, an alloy chilled roll, a steel roll, and a metal roll having hard chrome plated on the roll surface can be used, and as an elastic roll, for example, natural rubber, styrene rubber, nitrile Rolls made of rubber, chloroprene rubber, chlorosulfonated ethylene rubber, butyl rubber, polysulfide rubber, silicone rubber, fluorine rubber, urethane rubber, or synthetic resin such as aromatic polyamide, polyimide, polyether, polyester, polycarbonate, etc. Can be used. The nip pressure between the elastic roll and the metal roll is preferably set to about 125 to 350 kN / m. The surface temperature of the metal roll is preferably 130 to 250 ° C, more preferably 150 to 200 ° C. If the temperature is too low, a sufficient smoothing effect may not be obtained and the print quality may be deteriorated. On the other hand, if the temperature is too high, the yellowing of the paper is likely to occur due to excessive heating, and the resin roll deteriorates. There is a problem that is promoted.

  If necessary, sizing agents such as white carbon, clay, talc, titanium oxide, calcium carbonate, paper strength fillers, paper strength enhancers, yield improvers, reinforced rosin sizing agents, emulsion sizing agents, water resistance agents Ordinarily used paper-making chemicals such as UV inhibitors may be added.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to these Examples.
The coated base paper of the present invention includes chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, PGWRMP, TMP, CTMP, and CGP, and pulps such as waste paper pulp such as DIP, recycled filler, light calcium carbonate, heavy Various fillers such as calcium carbonate, talc, clay and kaolin, sizing agents, fixing agents, yield improvers, paper strength enhancers and the like are suitably blended, and any of acidic, neutral and alkaline papers can be made. In the base paper of the present invention, no-size press base paper, base paper size-pressed with starch, polyvinyl alcohol, or the like can be used. Further, in order to obtain the required rigidity of the base paper, and further to obtain the density and smoothness, various flattening means including at least one combination of an elastic roll and a metal roll are applied.
<Base paper formulation> 70 parts LBKP (watering degree 440 mlcsf), 30 parts NBKP (watering degree 490 mlcsf) 30 parts 0.03 parts.
Pulp and internal chemicals were adjusted according to the above formulation, and a base paper having a basis weight of 70 g / m ² was made.
For this base paper, an online soft calender finishing device (metal roll: chilled roll having a surface roughness of less than Rmax 1.5 according to JIS B 0651, elastic roll: resin roll having a Shore D hardness of 90 of roll coating resin, (Linear pressure: 250 kg / cm, temperature: 160 ° C.) was used for flattening to produce a coated base paper.
All Examples and Comparative Examples (hereinafter also referred to as all examples) are manufactured by a papermaking process including a wire part, a press part, a dryer part, a calendar part, a reel part, and a winder part in this order.
The evaluation method is as follows.
[Filling yield]
About the obtained paper, the ash content based on JISP8128 was measured, and the filler yield was evaluated by the ratio of the ash content.
[Stiffness (bending stiffness)]
The obtained paper was measured according to JIS P 8143.
[Operability evaluation criteria]
◎: There is no fluctuation of the draw value in the press part, and stable operation is possible with the paper making as it is. ○: There is a slight fluctuation of the draw value in the press part, but there is no need to change the paper making speed ×: The fluctuation of the draw value in the press part If it does not slow down, paper breakage and quality fluctuations may occur.

Example 1
After adding the recycled filler (average particle diameter of 8 μm) as a filler to the pulp slurry composed of the above-mentioned base paper between the seed box and the inlet by adding 20 % by weight per the absolutely dry pulp raw material, the inlet freeness value is 285 cc. A coagulant (cationic polyethyleneimine (trade name: Polymin SK), hereinafter referred to as cationic PEI, manufactured by BASF Corp.) and an aggregating agent (Arakawa Chemical Industries, Ltd., anionic polyacrylamide (trade name: Polystron 117)) Hereinafter, anion PAM) is controlled on-line, a paper layer is formed by a twin wire system at a paper making speed of 1300 m / min, paper is dehydrated in the order of roll suction and suction blade, and a heat soft calender (roll surface temperature 150 ° C. is used). ).
The recycled filler is made by dewatering paper sludge, kneading with a kneading machine, extruding into a string shape of 3.5 mm in diameter with an extruder and cutting it to a length of 30 mm. Carbonization was performed by indirect heating at 450 ° C. for 2 hours in a carbonization furnace under low oxygen conditions. The obtained carbide was burned at 650 ° C. for 2 hours in a rotary kiln by a method in which no flame was directly blown. The obtained combustion ash was roughly crushed with a roll crusher, and this crushed combustion ash was dissolved in water to form a slurry in a stirrer, and the combustion ash slurried with a wet mill was refined. And it manufactured by classifying the combustion ash whose particle diameter is 10 micrometers or less with a classifier.

(Examples 2 to 4 and Comparative Examples 1 to 5)
Under the conditions shown in Table 1, coated base paper was produced in the same manner as in Example 1 except that. The production conditions and the evaluation results of the resulting coated base paper are shown in Table 1 together with Example 1.

Cationic PAM (cationic polyacrylamide) in the table is Ariston Chemical Co., Ltd. Polystron 311 (trade name), and cationic PAm (cationic polyamine) is Hakutoru Z103 (trade name) manufactured by Hakuto Co., Ltd. .
(Machine calendar) in the thermal soft calendar column of Comparative Example 5 indicates that flattening processing was performed using a machine calendar instead of the thermal soft calendar.

  It can be seen that the base paper obtained in the examples has higher filler yield and stiffness than the comparative example.

It is a schematic diagram of the example of the installation in this invention.

Explanation of symbols

4 Compound chest 5 Machine chest 6 Seed box 7 Cleaner 9 Screen 10 Stock inlet 11 Paper machine 12 Machine part (wire part)
13 Freeness Measuring Machine 14 Arithmetic Processing Device 20A Cation Demand Measuring Device 20B Broke Demand Control Device 30A Cation Demand Measuring Device 30B GP Demand Control Device

Claims (1)

(1) In the papermaking raw material preparation process in which the reclaimed filler recovered from the papermaking sludge is added between the seed box and the inlet between 5 to 30% by weight of the dry pulp raw material , the cation demand measurement value is obtained by an online cation demand measuring device. Based on this, the amount of cationic coagulant added to the slurry of the papermaking raw material is controlled and / or the freeness is measured during the supply process from the seed box to the wire part, and the coagulant and the flocculant according to the freeness measurement value are measured during the supply process. A step of controlling the amount of addition , ( 2 ) a step of forming a paper layer by performing initial dehydration with a roll suction and / or suction blade in a forming zone using a twin wire system, and ( 3 ) an elastic roll and a metal roll The surface of the coated base paper is flattened by a flattening processing means including at least one combination of Method for producing a coating base paper, characterized in that step, only free and ash were measured in accordance with JIS P 8128 is 16 to 20% by.

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