JP2010236155A - Coated paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain coated paper using recycled particles having necessary characteristics as a coating pigment for papermaking as a pigment for a coated layer and having a stable quality. <P>SOLUTION: The coated paper uses deinked floss separated from pulp fibers in the deinking process of wastepaper treatment equipment manufacturing wastepaper pulp as a main raw material. The coated paper has the coated layer using the recycled particles obtained by dehydrating, drying, combusting and grinding the raw material as the coating pigment. The combustion process comprises at least two steps of combustion processes having a first combustion furnace 14 and a later second combustion furnace 32 combusting again the deinked floss combusted in the first combustion furnace 14. The first combustion furnace 14 carries out combustion at a temperature ranging from 300°C or above to under 500°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a coated paper having a coating layer using deinked floss as a main raw material and using regenerated particles obtained by a predetermined production method as a coating pigment.

  Paper sludge discharged from various processes in a pulp and paper mill contains a significant proportion of inorganic fillers and inorganic pigment particles, and these paper sludge is recovered and recovered in incinerators such as fluidized bed furnaces and stalker furnaces. The organic matter inside is burned to reduce the volume of papermaking sludge and is recovered as energy.

  However, since papermaking sludge contains a large amount of inorganic substances, a large amount of incinerated ash (inorganic substances) remains even after combustion, and there is a limit to volume reduction. Therefore, efforts have been made to use this incinerated ash as an auxiliary material for cement raw materials and as a soil improvement material. However, the amount of incineration ash used as an auxiliary for these cement raw materials and soil improvement materials is very small, and in the end, most of the incineration ash is landfilled.

  Therefore, not only recovering as thermal energy by incineration, but also reusing inorganic substances in paper sludge as paper fillers, pigments, plastic fillers, etc. is related to environmental problems as well as improving the waste paper utilization rate in the paper industry. This is an important improvement issue.

  However, the incineration ash of papermaking sludge contains organic substances that remain without being burned as carbon, so the whiteness is low, or the sintering of inorganic substances progresses, and the particle diameters are uneven and large. It is not suitable for use as a coating pigment for papermaking.

  Therefore, Patent Document 1 discloses a method of using after incineration ash is reburned to improve whiteness.

  However, in the method of recombusting the incinerated ash of Patent Document 1, it is necessary to set the recombustion temperature to 500 ° C. to 900 ° C. in order to completely burn the unburned carbon, and the whiteness of the incinerated ash is about 50%. However, when used as a coating pigment for papermaking, it does not look good, and when the reburning temperature is set to over 900 ° C., the incineration ash (inorganic material) sinters and melts and is extremely hard. It was found that the obtained reburned product is not suitable for coating pigments because it tends to cause quality problems such as wear and streaks of coating equipment and members. Moreover, even if it performs a calendar process, the problem that the smoothness is inferior arises in the coating layer surface containing the reburned material as a coating pigment.

  In this regard, it may be possible to pulverize the re-incinerated ash and reduce its particle size to reduce wear and improve smoothness. However, when used as an internal filler, the yield during papermaking is low. Since the incinerated ash itself is extremely hard, the energy cost for pulverization becomes extremely high.

  Furthermore, the so-called cement-like substance represented by calcium aluminate is generated in the reburned product due to overcombustion, and the reburned product is agglomerated and solidified at the time of water dispersion. It becomes broad and tends to generate excessively or too little reburned matter, resulting in a problem of deteriorating the quality of the used coating layer.

  In Patent Document 2, paper sludge is supplied into a reactor into which an oxygen-containing gas has been injected, and oxidized at 250 ° C. to 300 ° C. under a heating and pressurization of about 3000 psig for 0.25 hours to 5 hours. A method of regenerating the inorganic material as a papermaking pigment has been proposed.

  However, since this method is based on wet air oxidation treatment with the paper sludge remaining in the liquid phase, organic matter removal is not sufficient, and the resulting pigment has low whiteness and uneven particle size, making papermaking It is unsuitable for use as a pigment for the use, and the reaction operation is complicated and the cost is high.

  On the other hand, Patent Document 3 proposes a method in which after making papermaking sludge into PS charcoal, it is further incinerated in an internal heat kiln furnace to produce white clay as a papermaking raw material. However, this method has a great demerit that not only energy cannot be effectively extracted from the papermaking sludge but also input energy is required because the papermaking sludge is fried. In addition, by smoldering, the volatile matter is removed and the organic matter is difficult to burn (oxidize), so-called “residual carbon”, which makes it difficult to burn in the post-process and has a long combustion time due to the residual carbon. It is difficult to obtain a high degree of whiteness unless applied, and the generated white clay has the same problems as in Patent Document 1, and the particle size is uneven and large, and also from a heavy oil burner used in an internal heat kiln. Contamination due to carbon and sulfur oxides occurs, and it cannot be used as a papermaking pigment.

  Patent Document 4 discloses a method for continuously drying, carbonizing and burning wastewater treatment sludge in a rotary kiln furnace. Since the wastewater treatment sludge used in this method is composed of sludge having various sources, there is a problem that the resulting granulated / molded material also fluctuates due to fluctuations in the source and amount generated. In this patent document, granulation and shaping prior to combustion are considered to be performed for uniform combustion, but the solid content concentration described in the embodiment is 40% to 60% ( In other words, when drying, carbonization, and combustion are continuously performed in a rotary kiln furnace in a moisture content of 60% to 40%), sludge particles are formed by rotation of the kiln furnace regardless of whether the sludge is in a dry state or carbonized state. The process will be forced to proceed.

  Therefore, if the drying is insufficient, a large amount of unburned matter remains inside the particles, resulting in incomplete combustion and a decrease in whiteness.On the other hand, overdrying results in complete combustion but overburning. As a result, the hardness of the obtained regenerated particles becomes high, and when this regenerated particle is used, there is a problem that wire wear in a paper machine and cutter blade wear when cutting paper are likely to occur.

  In the first place, the biggest problem in the case of using papermaking sludge as described in Patent Documents 1 to 4 as a raw material is that the papermaking sludge used as a raw material flows out of the wire in the papermaking process and is washed in the pulping process. Collected from wastewater containing solids generated in the process, in the wastewater treatment process, solids separated and collected by solid content separation equipment using precipitation or flotation, etc., contaminants removed in the waste paper treatment process It is a point that various sludge such as things are mixed.

  Among these papermaking sludges, for example, those that flow out through the wire in the papermaking process are mixed with a paper strength agent and the quality varies due to changes in the papermaking product in the papermaking process. In addition, the papermaking sludge collected from the wastewater treatment process is mixed with a flocculant, and a large fluctuation occurs due to papermaking products in the whole factory, fluctuations in production volume, or in-process washing of production facilities.

  In the papermaking sludge generated from the washing process in the pulping process, fluctuations occur in chip moisture and pulp production conditions, and various fillers and substances that cannot be made into pigments are mixed, resulting in quality fluctuations. Therefore, if all the papermaking sludge is used without selection, the quality as a papermaking filler or coating pigment is greatly reduced, and the quality fluctuation is extremely large and unstable.

  That is, regenerated particles obtained by a conventionally known method are not suitable for use as a coating pigment for papermaking, lack quality stability, and have the characteristics required as a filler for papermaking or a coating pigment. It was difficult to obtain the regenerated particles provided, and it was difficult to obtain coated paper with stable quality.

JP-A-11-310732 Japanese Examined Patent Publication No. 56-27638 Japanese Patent Laid-Open No. 54-14367 Japanese Patent No. 3812900

  The main problem to be solved by the present invention is to obtain a coated paper having a stable quality using regenerated particles having properties necessary as a coating pigment for papermaking as a pigment for a coating layer. .

  The present invention that has solved this problem is as follows.

[Invention of Claim 1]
Using the deinked floss separated from the pulp fiber in the deinking process of the used paper processing equipment for manufacturing used paper pulp, the regenerated particles obtained by dehydrating, drying, burning and grinding the main material are used for coating. Coated paper having a coating layer used as a pigment of
The combustion process has at least two stages of combustion steps, including a first combustion furnace and a second combustion furnace after which the deinking floss burned in the first combustion furnace is burned again;
In the first combustion furnace, the combustion treatment is performed at 300 ° C. or higher and lower than 500 ° C.,
Coated paper characterized by that.

[Invention of Claim 2]
The first combustion furnace is an internal heat kiln furnace in which the main body is placed horizontally and rotates around a central axis, and the moisture content of the raw material after the dehydration step is 40% or more,
The coated paper according to claim 1.

[Invention of Claim 3]
Hot air of 300 ° C. or more and less than 500 ° C. is blown so that the oxygen concentration in the internal heat kiln furnace is 0.2% to 20%.
The coated paper according to claim 1 or 2.

[Invention of Claim 4]
The second combustion furnace is an external heat kiln furnace in which a main body is placed horizontally and rotates around a central axis, and is parallel to a spiral lifter and an axial center on the inner wall of the kiln furnace from one end side to the other end side. At least one of the parallel lifters is disposed,
The coated paper of any one of Claims 1-3.

[Invention of Claim 5]
As the raw material pulp of the coated paper base material, waste paper pulp is used as a main raw material, and the waste paper pulp is an enzyme-treated waste paper pulp obtained by enzymatic treatment with a complex enzyme.
The coated paper of any one of Claims 1-4.

  According to the present invention, a coated paper having a stable quality is obtained by using, as a pigment for a coating layer, regenerated particles having characteristics necessary as a coating pigment for papermaking and avoiding excessive combustion.

It is a schematic diagram of a manufacturing facility. It is a schematic diagram of a 2nd combustion furnace, (a) is a longitudinal cross-sectional view, (b) is an expanded view of an inner surface.

Next, an embodiment of the present invention will be described.
In order to obtain excellent regenerated particles, the present inventors in JP 2008-127704 A, as a main raw material, deinking floss separated from pulp fibers in the deinking process of waste paper processing equipment for producing paper pulp, A method for producing regenerated particles, wherein the main raw material is subjected to dehydration, drying, combustion, and pulverization steps to obtain regenerated particles, wherein the drying and combustion step is a series of steps in which the dehydrated raw material is dried and burned in series. The first combustion furnace and the deinking floss burned in the first combustion furnace are combusted again, and have a second combustion furnace, and have at least two stages of combustion processes, and then pulverized to obtain regenerated particles A method for producing regenerated particles with operation was proposed.

  Furthermore, the specific proposal content blows in hot air of 500 degreeC-650 degreeC so that the oxygen concentration in a 1st (next) combustion furnace (internal heat kiln furnace) may be 0.2%-20%, In the second combustion furnace, the combustion product from the internal heat kiln furnace is burned at a temperature of 550 ° C to 750 ° C.

  However, the deinking floss separated from the pulp fiber in the deinking process for producing the used paper pulp contains fine inorganic fine particles as a raw material for the regenerated particles, and is difficult to use as used paper pulp. Latex, which is an organic polymer frequently used for printing, contains many ink components applied by printing, and the deinking floss itself undergoes a combustion reaction (oxidation) and burns in the combustion process, so the hot air proposed in the previous application It has been found that there is a problem that heat generation occurs more than the heat treatment by, causing excessive combustion of the raw material.

  Excessive combustion leads to the following problems. (1) The raw material turns yellow due to high-temperature combustion, resulting in a decrease in whiteness. (2) Hard materials such as gelenite (reference: Japanese Patent Application No. 2007-22377) are likely to be generated by melting the raw material, and the degree of wire wear in the papermaking equipment is increased. (3) Since aggregates are formed by melting the raw materials, the pulverization energy is increased and the processing efficiency is reduced in the subsequent pulverization step. (4) Since the surface of the raw material is exposed to a high temperature and melted before the inside of the raw material, the combustion reaction (oxidation reaction) does not proceed to the inside of the raw material, and organic matter (carbon) remains (resulting in a decrease in whiteness) ). (5) A hydration hardening substance such as calcium aluminate is generated by decomposition and reaction of the raw material, and aggregation and solidification of the slurry occur.

  As a means for solving the above problems, the inventors of the present invention focused on a measure for controlling excessive combustion, and as a result of intensive studies, the deinking floss as a raw material burned in the first combustion furnace. First, the combustion temperature of the organic component gas is limited to the temperature in the primary combustion furnace necessary to release the combustion gas (combustible gas) generated by gasification of the organic component contained in the deinking floss. It has been found that the above problem can be solved by promoting only (oxidation reaction).

  Furthermore, in the primary combustion furnace, in order to ensure an oxygen concentration of 0.2% to 20% necessary for burning the combustion gas (combustible gas), and to prevent excessive combustion of the deinking floss, In addition to supply, it has been found that measures to increase the moisture content of the deinking floss as a raw material are effective. According to the knowledge of the present inventors, securing an oxygen concentration of 0.2% to 20% in the primary combustion furnace is an in-furnace environment in which combustion is promoted, and therefore, excessive combustion of the deinking floss is caused. It tends to occur.

  However, the water content after dehydration of the deinked floss as a raw material is 40% or more, preferably 40% or more and less than 90%, more preferably 45% or more and 70% or less, and particularly preferably more than 50% and less than 60%. It has been found that supplying in the primary combustion furnace in a state is suitable for preventing excessive combustion of the deinking floss. The reason for this is that by supplying the first combustion furnace with a high water content, the temperature in the furnace decreases due to the evaporation of water in the first combustion furnace, suppressing the self-combustion of the deinking floss, and the combustion that occurs It is considered that combustion of only gas (combustible gas) can be promoted and an excessive increase in combustion temperature can be suppressed.

  More preferably, in the primary combustion furnace, the deinking floss as a raw material does not self-combust, and the combustion gas (combustible gas) generated by gasification of organic components contained in the deinking floss is released. Measures to keep only the temperature in the primary combustion furnace as necessary to promote the combustion reaction (oxidation reaction) of the organic component gas, and in the primary combustion furnace, the combustion gas (combustible gas) ) To increase the moisture content of the deinking froth used as a raw material in addition to supplying hot air in order to secure the oxygen concentration of 0.2% to 20% necessary for burning It was found that higher quality regenerated particles can be obtained in combination with

  On the other hand, more preferably, a spiral lifter and / or a parallel lifter parallel to the axial center is disposed on the inner wall of the secondary combustion furnace from one end side to the other end side of the secondary combustion furnace. Uniform combustion and uniform quality can be achieved.

  According to the knowledge of the inventors described above, in the primary combustion furnace, the raw material deinking floss is exposed to the combustion reaction at a low combustion temperature, and after obtaining a homogeneous primary combustion furnace outlet raw material, the remaining white It is necessary to combust as much as possible the carbon component that causes a decrease in the degree of fuel, so it is necessary to combust the raw material slowly, and in order to continuously perform as uniform combustion as possible in the secondary combustion furnace It has also been found that a method of appropriately controlling the raw material conveying speed in the above method is considered to be most suitable, and as a means for that, it is possible to adjust the raw material conveying speed by using a lifter facility. However, since a known lifter is generally manufactured from an iron material, iron is contained in the raw material as a contaminant, which causes a problem of reducing whiteness due to oxidation of iron. Therefore, the present inventors provide a technology capable of producing high-quality regenerated particles, such as without causing the iron oxidation problem and no reduction in whiteness, by providing a stainless steel lifter in the secondary combustion furnace. I found.

  An external heat kiln is preferably employed as the structure of the secondary combustion furnace. In the external heat kiln, the direct fire of the burner is not directly exposed to the raw material, so overheating can be prevented and uniform combustion quality (high whiteness can be obtained). On the other hand, the internal heat kiln has an advantage that the refractory attached inside has heat insulation and at the same time emits far infrared rays and can be heated with a small amount of heat.

  Further, when combustion is performed in an external heat kiln furnace that is preferably used as the second combustion furnace, the combustion temperature adjustment according to the combustion state fluctuation of the combustible in the second combustion furnace is achieved by external heat that can be adjusted in temperature, such as an electric furnace. In addition, the whiteness is not lowered and the combustion product can be uniformly heated while suppressing an excessive oxidation reaction, so that the quality of the combustion product can be stabilized. Also, by directly heating the combusted material with internal heat, it becomes possible to uniformly and sufficiently heat the combusted material according to the combustion status of the combusted material. Combustion according to fluctuations can be performed. Further, the rotation of the kiln furnace causes the combustion products to be unevenly distributed along the rotation direction, and the combustion products roll due to friction between the combustion products and the inner wall, and are gently stirred in the kiln furnace to the discharge port. Since the combustion product moves, it becomes possible to suppress the pulverization of the combustion product, and as a result, the quality and shape of the final combustion product become stable.

  As described above, drying and combustion operations, in particular, combustion treatment is performed in the first combustion furnace so that the ratio of unburned matter in the burned product is 2 to 20% by mass, and then the remaining organic matter, carbide, etc. In the second combustion furnace, the unburned material is burned in at least a two-stage combustion furnace, so that the regenerated particles that have the characteristics required especially as fillers for papermaking and pigments for coating can be made uniform and stable. Can be manufactured.

  Combustion kiln furnaces used as suitable combustion furnaces can be lifted and agitated without slipping the dried and burned material by making the internal refractory into a hexagonal or octagonal shape instead of a circular shape, It is possible to suppress the generation and suppress the dust from being mixed into the exhaust gas, thereby improving the product yield. About the structure of a 2nd combustion furnace, although it can select suitably in view of these various conditions, it is optimal to provide a lift for any system.

  As described above, in the combustion process in the production of regenerated particles, it is necessary to burn the regenerated particles without overburning them. However, some overburned regenerated particles may occur due to combustion fluctuations in the combustion process. In that case, the reburned regenerated particles are suspended in water as a filler or coating pigment, and the particle size is adjusted accordingly. For this reason, pulverization is carried out, but the hydrated and hardened substance produced by overcombustion causes a hardening reaction within the manufacturing process and aggregates and solidifies. Or there are problems in operability and quality, such as increasing the product particle size or increasing the viscosity.

  As a result of earnest examination of the factors that cause the problem of aggregation and solidification, calcium aluminate and kaolin, which are the main components of paper sludge, are decomposed into calcium oxide, metakaolin, alumina, and silicic acid by overcalcination, and calcium aluminate is produced. understood. When calcium aluminate is mixed with water, a hydration hardening reaction occurs and solidifies. Further, metakaolin produced by calcination of kaolin acts as an accelerator for the hydration hardening reaction. Therefore, it was considered that when the baked ash (burned product) containing the hydrated and hardened substance generated by overcombustion was suspended in water, it was agglomerated and solidified due to a synergistic action with the accelerated curing of metakaolin.

  In order to prevent the formation of hydrated and hardened substances, the combustion conditions in the firing furnace have been studied, but in the actual manufacturing process, there were found firing conditions that produced calcium aluminate in a small amount due to various variable factors.

  Based on these findings, the present inventor has studied a measure for improving production stability and quality by preventing aggregation and solidification by modifying a hydrated and cured substance. It has been found that solidification can be prevented by reacting calcium aluminate with calcium sulfate dihydrate and modifying it to a substance called ettringite.

  Ettringite is called satin white and is a substance that is generally used as a coating pigment. Calcium aluminate, which is originally not suitable as a papermaking chemical, is modified to satin white used as a coating pigment. Therefore, it not only prevents aggregation and solidification, but also provides the effect of imparting gloss, whiteness and opacity to the paper surface.

  On the other hand, the excess calcium sulfate remaining in the reaction is a soft white substance that is insoluble in both acid and alkali. Therefore, when used as an internal filler, it improves wire wear and whiteness. Contribute.

  The addition of calcium sulfate dihydrate is effective in that the residual chemical can be used as a papermaking chemical at the same time as the modification of a hydration curable substance that is not suitable as a papermaking chemical.

  On the other hand, for example, when papermaking sludge is burned, (1) in the invention described in Japanese Patent Application Laid-Open No. 2003-119695, the dried product is substantially free of oxygen with an oxygen concentration in the furnace of 0.1% by volume or less. Specifically, drying and carbonization are performed by an indirect heating furnace (external heat combustion furnace) in a poor oxygen state. Next, a method has been proposed in which carbon derived from an organic substance contained in a carbide is oxidized and decarbonized, specifically, a whitening treatment is performed using an indirect heating furnace. The invention also teaches the use of an internal heat rotary kiln furnace for the latter whitening treatment.

  On the other hand, the applicant teaches (2) JP 2002-275785 to use a rotary kiln furnace for recombustion after carbonization.

  Further, the present applicant, in (3) Japanese Patent No. 3808852, “using a deinking sludge as a raw material sludge and drying it, and drying the deinked sludge from the top of the cyclone combustion furnace A primary combustion step of obtaining a primary combustion product containing unburned content by being supplied to the inside and swirling and descending, and a primary combustion product communicating with the cyclone-type combustion furnace and containing unburned content from the lower end thereof And a secondary combustion step of burning until a predetermined whiteness is obtained using the heat of combustion of the primary combustion step while promoting contact with oxygen by mechanical stirring. "A method for producing a white pigment or white filler from sludge".

  In addition, in (4) Japanese Patent Application Laid-Open No. 2004-176208, when the filler is produced from “the wastewater treatment sludge in the coated paper production process”, the formed sludge is “dried, carbonized and burned in one rotary kiln furnace”. Propose that.

  The above (1), (2) and (4) do not use deinking floss separated from pulp fibers in the deinking process of the used paper processing equipment for producing used paper pulp, but mainly use the above-mentioned papermaking sludge. It is a raw material. The obtained regenerated particles are considered to be different from the regenerated particles “aggregates” as in the present invention.

  On the other hand, according to the method (3), it was considered that regenerated particles similar to those obtained by the present invention could be obtained. However, in this method, a cyclone type fluid combustion furnace is used to burn dry matter and then perform secondary combustion. The cyclone type fluid combustion furnace itself is thought to be derived from the form of the cyclone type, but the cyclone type supplies raw materials and air of several tens to several hundreds of microns as a swirling flow from the supply port, and the air and swirling action causes the effect of air and air. Because the fine particles contained in the raw material are discharged out of the system together with the exhaust gas and the product yield is reduced, the combustion time (heating time) of the deinking floss as the main raw material is short. Thus, it has been found that unburned matter tends to occur, the quality (particularly the shape) of the finally obtained combustion product is not constant, and the whiteness of the combustion product may vary.

  Therefore, the present inventor has repeatedly studied a means for obtaining regenerated particles with stable quality by preventing the formation of a hydrated and cured substance of the obtained regenerated particles without overburning, thereby achieving stability during water dissolution. The combustion process includes a first combustion process and a combustion process of at least two stages including a second combustion process after which the deinking floss burned in the first combustion furnace is burned again. It has been found that regenerated particles with stable quality can be obtained by performing a combustion treatment at 300 ° C. or higher and lower than 500 ° C. in one combustion step. In a more preferable method for producing regenerated particles, calcium sulfate dihydrate is added as a coagulation inhibitor when regenerated particles dissolved in water at 300 ° C. to less than 500 ° C. in the first combustion step are dissolved in water. Thus, it has also been found that high-quality regenerated particles that do not produce a hydrated and cured substance can be produced.

  As a mode for obtaining suitable regenerated particles that do not generate a hydrated and cured substance, the raw material after dehydration is dried and burned in series, and the combustion time (residence time) in the primary combustion furnace by internal heat is 30. 1 to 90 minutes, more preferably 40 minutes to 80 minutes, and most preferably 50 minutes to 70 minutes. (Direct heating) Kiln furnace is used to dry and burn the raw material after dehydration, and then the combustion time (residence time) for burning again the combustion product obtained from the first combustion furnace is more preferably 60 minutes or more. Is used for 60 minutes to 240 minutes, especially 90 minutes to 150 minutes, optimally 120 minutes to 150 minutes, using a second combustion furnace with external heat, preferably the main body is placed horizontally and rotated around the central axis Thermal (indirect heating) kiln furnace, especially the combustion temperature can be adjusted easily The thermal electric furnace, and adopts a method of combustion.

  In the embodiment described later with reference to the drawings, an internal heat kiln furnace is selected as the first combustion furnace, and an external heat kiln furnace is selected as the second combustion furnace, and a known combustion furnace is used as these kiln furnaces. it can. Moreover, it is not limited to a kiln furnace, A well-known apparatus, such as a fluidized bed furnace, a stalker furnace, a cyclone furnace, a semi-dry distillation / negative pressure combustion type furnace, can also be used.

  In a preferred aspect of the present invention, the first combustion furnace is performed with internal heat, and the subsequent second combustion furnace is performed with external heat. Furthermore, as this external heat second combustion furnace, a known combustion method such as an indirect heating type combustion furnace using heavy oil or the like as a heat source may be employed.

  According to the internal heat kiln furnace that can be suitably used as the first combustion furnace, drying and combustion can be performed in one furnace, and drying and combustion can be performed slowly and stably from the supply port to the discharge port. It progresses and pulverization of combustion products is suppressed. In addition, when combusted in an external heat kiln furnace that can be suitably used as the second combustion furnace, the combustible can be discharged from the end of the combustible with a predetermined residence time from the discharge port of the other end and further combusted by external heat. Since uniform heat is applied to the gas, the combustion becomes uniform and does not cause variations in combustion. Furthermore, the combustion product is gently agitated by friction caused by the rotation of the inner wall of the kiln furnace, so that it is difficult to produce fine powder. As a result, the quality and shape of the final combustion product are stabilized.

  In the conventional first combustion furnace, the moisture content is 40% in order to efficiently burn fine fibers in the raw material, latex that is an organic polymer frequently used for coated paper, ink components applied by printing, and the like. Although the method of dehydrating and drying to less than that and combusting at a high temperature is also described in the publicly-known literature described above, in the knowledge of the present inventors, in the first combustion furnace, the conventional method of 300 ° C. to less than 500 ° C. Compared to the raw material, the organic matter contained in the raw material is converted into combustion gas, and the combustion gas is combusted (oxidized), which stabilizes the ionicity of the obtained regenerated particles. In a preferred method for producing regenerated particles, uniform dispersion can be achieved by combining with an aggregation inhibitor mainly composed of calcium sulfate dihydrate, contributing greatly to stabilizing the quality of the obtained regenerated particles and improving whiteness. Ikoto also have found.

  As described above, uniform and stable regenerated particles can be obtained by performing the drying and combustion processes in an internal heat kiln furnace and an external heat kiln furnace in at least two stages of combustion furnaces.

  The internal heat or external heat kiln furnace used as a suitable combustion furnace can lift and agitate the combusted material without slipping by making the internal refractory into a hexagonal or octagonal shape instead of a circumferential shape, In reality, the kiln furnace has a cylindrical shape, and it is optimal to provide a lifter for stirring the combusted material in terms of uniform combustion of the raw material and uniform quality. This is considered to be related to the fact that the present invention intends to burn the entire raw material carefully at a low temperature in the first combustion furnace.

Here, the selection of the combustion furnace most focused on when the present inventors obtain suitable regenerated particles will be described.
Conventionally used combustion furnaces can be broadly classified into four types: stalker furnaces (fixed bed), fluidized bed furnaces, cyclone furnaces, and kiln furnaces. As a result of repeated examinations of the manufacturing process, the following matters became clear.

・ For the stalker furnace (fixed bed), it is difficult to adjust the degree of combustion of the deinking floss, and the combustion products are not uniform. In addition, the combustion of the deinked floss with a lot of ash causes dust to fall from the clearance between the grate. Therefore it is not suitable. Since air is blown up and burned under the combustion material through the grate, calcium carbonate or the like becomes fly ash and is sent to the exhaust gas facility together with the exhaust gas.

-Since the fluidized bed furnace uses a particulate fluid medium such as silica sand as the fluid medium in the furnace, there is a problem that the silica sand is mixed into the reclaimed filler and the quality is deteriorated. Uniform stirring is not possible. After the cinnabar sand is mixed with the fluidized bed and combusted, the cinnabar sand and the burned material are separated, and the cinnabar sand is returned to the combustion furnace, and only the burned material is taken out. Since combustion is performed in a floating state with dredged sand, it is difficult to adjust the degree of combustion, resulting in variations in quality. Since the combustion furnace is burned while passing through the stoker (stepped shape) of the combustion furnace with a predetermined width, the ash is not sufficiently stirred and the combustion varies in the width direction. In addition, the combusted material is pulverized by friction and collision with high hardness silica sand, and the fly ash is discharged out of the system to reduce the yield.

・ The cyclone furnace passes through the furnace in an instant, and the fixed carbon in the combustion product cannot be burned sufficiently, leading to a decrease in whiteness. Further, since the fine particles are not separated by the cyclone but are sent to the exhaust gas treatment process together with the exhaust gas, the yield is lowered.

  As a result of intensive studies on the above problems, the combustion furnace is selected as the most suitable combustion means to be burned in a kiln furnace, and is the optimum embodiment in the present invention for the following reasons. It has been found that it is preferable to use the first combustion furnace as the internal heat kiln and the subsequent second combustion furnace as the external heat kiln for the following reason.

  Since the external heat kiln furnace has a configuration in which heating equipment is provided outside the kiln furnace, the structure of the kiln furnace is complicated, and the combustion product is indirectly dried and burned, so a large amount of heat source is required. When the external heat kiln furnace is used as the first combustion furnace for the drying and combustion treatment of the raw material having a high water content after dehydration according to the present invention, the drying / combustion efficiency is lowered and the productivity is poor. The temperature control becomes difficult and requires a large energy cost, and the cost effectiveness is extremely low.

  In addition, when the internal heat kiln furnace is used as a secondary combustion furnace, a large amount of diluted air is required to adjust the temperature in the furnace when the remaining carbon is burned. Since it is difficult to uniformly transmit heat into the internal heat kiln furnace, and furthermore, it is difficult to suppress fluctuations in the furnace temperature, there is a problem in that overburning of combustion products and uneven combustion are likely to occur.

  In addition, heavy oil burner residue from heavy oil burners usually used for heating is contaminated by residual carbon and sulfur oxides, resulting in decreased whiteness and variability at the product stage, making it difficult to equalize the quality of the resulting combustion products. Problems arise.

<Method for producing regenerated particles>
Next, a method for producing regenerated particles will be described with reference to the drawings.

  A preferred method for producing regenerated particles in the present invention includes a dehydration step, a drying step, a combustion step, and a pulverization step, and further includes a deinking floss agglomeration step, a granulation step, and a classification step between the steps. Also good.

  FIG. 1 shows a partial configuration example (including a drying / combustion process and a combustion process) of a production facility flow of regenerated particles. This equipment is equipped with various sensors, and controls the state of combustibles, equipment, and processing speed.

〔material〕
In the used paper pulp manufacturing process, in order to continuously produce used paper pulp of stable quality, used paper is selected and selected, and used paper of a certain quality is used. For this reason, the types, ratios, and amounts of inorganic substances brought into the used paper pulp manufacturing process are basically constant. In addition, even if the waste paper contains plastics such as vinyl and film that cause fluctuations in unburned material, these foreign substances are removed at a stage before the deinking step for obtaining the deinking floss. Accordingly, the deinking floss is a raw material for producing regenerated particles having extremely stable quality as compared with papermaking sludge generated in other processes such as a factory drainage process and a papermaking raw material preparation process.

  Here, the deinking floss refers to what is separated from the pulp fiber in the deinking process for removing ink adhering to the used paper in the used paper processing process for producing the used paper pulp.

[Dehydration process]
The deinking floss separated from the pulp fibers in the deinking process for producing waste paper pulp is subjected to various operations and dehydrated by a known dehydration equipment (not shown). In one example of this embodiment, water is separated from the deinking floss and dehydrated by, for example, a screen as a dehydrating means. In this screen, it is desirable that the deinking floss dehydrated to 90% to 97% is sent to a dehydrating means such as a screw press and further dehydrated to a predetermined moisture content. The material after dehydration (deinking floss) should be in a high water content state of 40% or more, preferably 40% or more and less than 90%, more preferably 45% or more and 70% or less, and particularly preferably more than 50% and 60% or less. Is desirable.

  If the moisture content of the raw material after dehydration exceeds 70%, the temperature of the drying / combustion treatment in the first combustion furnace will be lowered, the energy loss for heating will be great, and the unevenness of the raw material will be easily generated and uniform. It is difficult to proceed with proper combustion. In addition, there is a problem that the moisture in the exhaust gas discharged increases, the recombustion treatment efficiency in dioxin countermeasures decreases, and the load on the exhaust gas treatment facility increases. On the other hand, if the moisture content of the raw material after dehydration is as low as less than 40%, it causes excessive combustion of the deinking floss. It also goes against the reduction of dehydration energy.

  As described above, if the deinking floss is dehydrated in a multi-stage process and abrupt dehydration is avoided, the outflow of the inorganic substance can be suppressed and there is no possibility that the deinking floss floc becomes too hard. In the dehydration treatment, an auxiliary agent for improving the dehydration efficiency such as an aggregating agent for aggregating the deinking floss may be added, but it is preferable to use an aggregating agent that does not contain iron. When iron is contained, the whiteness of the regenerated particles may be reduced due to oxidation of iron.

  The deinking process of deinking floss is preferably adjacent to the recycled particle manufacturing process from the viewpoint of production efficiency, but it is also possible to transport the dehydrated product by installing equipment adjacent to the waste paper pulp manufacturing process in advance. It can also be transported to a quantitative feeder by a transport means such as a truck or a belt conveyor, and supplied from this quantitative feeder to the drying / combustion process.

[Crushing process]
The raw material 10 after dehydration is supplied to the first combustion furnace 14 by a pulverizer (or pulverizer) or the like, with an average particle size of 40 mm or less, preferably an average particle size of 3 mm to 30 mm, more preferably an average particle size of 5 mm. It is preferable to align the particle diameter to ˜20 mm, and it is preferable to align the particle diameter so that the ratio of the particle diameter of 50 mm or less is 70 wt% or more, preferably 90 to 100%. In order to achieve combustion without causing a heat change of the calcium carbonate contained in the deinking floss, it is preferable that the particle diameter of the raw material is uniform. However, if the average particle diameter is less than 3 mm, overburning tends to occur. If the particle diameter exceeds 40 mm, it is difficult to uniformly burn the raw material core.

  The average particle diameter and the ratio of the particle diameter are values measured using a sample solution sufficiently dispersed by a stirring type disperser. In addition, the particle diameter in each combustion process is the value measured with the metal plate sieve based on JISZ8801-2: 2000.

[First combustion process] (Drying and combustion process)
The raw material 10 subjected to dehydration, pulverization, etc. is cut out from the storage tank 12 and supplied to the first combustion furnace 14. The first combustion furnace 14 has an internal heat kiln furnace system in which a main body is placed horizontally and rotates around a central axis, and the raw material 10 is charged from one side of the internal heat kiln furnace 14 by a charging machine 15. In the internal heat kiln furnace 14, the hot air generated in the hot air generation furnace 20 is sent from the discharge port side of the internal heat kiln furnace 14 so as to counter-flow with the flow of the raw material (dehydrated product) 10. An exhaust gas chamber 16 is provided on one side of the internal heat kiln furnace 14, and an exhaust chamber 18 is provided on the other side. Raw material 10 that passes through the discharge chamber 18, is blown from the other side of the internal heat kiln furnace 14, charged from the one side, and sequentially transferred to the other side as the internal heat kiln furnace 14 rotates. Drying and burning are performed.

  In this way, in the main drying / combustion process, the dehydrated product 10 is gently dried from the supply port to the discharge port by drying and burning in the internal heat kiln furnace in which the main body is placed horizontally and rotates around the central axis. Drying and combustion of organic content can be performed, pulverization of the combustion product is suppressed, the degree of combustion of the dehydrated product 10 having various properties such as agglomerate formation, hard and soft, and the grain alignment, It can be performed stably. In addition, drying can be divided into separate steps and dried by, for example, a blow-up type dryer.

  Here, the hot air blown into the internal heat kiln furnace 14 preferably has an oxygen concentration of 0.2% to 20%, more preferably 1% to 17%, and more preferably 7% to 15%. Particularly preferred. In this regard, the oxygen concentration in the internal heat kiln furnace 14 varies depending on the state of combustion because oxygen is consumed by the combustion (oxidation) of the raw material 10. And when oxygen concentration is too low, it will become difficult to aim at sufficient combustion. However, the oxygen concentration can be maintained and adjusted by blowing or exhausting oxygen-containing gas such as air by the hot-air generator 20 or the like, and oxygen-containing gas is blown or exhausted. Thus, the temperature in the internal heat kiln furnace 14 can be finely adjusted, and the raw material 10 can be burned uniformly without unevenness.

  The furnace temperature of the first combustion furnace 14 is 300 ° C. or higher and lower than 500 ° C., preferably 400 ° C. or higher and lower than 500 ° C., more preferably 400 ° C. or higher and 450 ° C. or lower. In the first combustion furnace 14, it is preferable to combust in a temperature range of 300 ° C. or more and less than 500 ° C. for the purpose of moderately burning easily combustible organic substances and suppressing generation of residual carbon that is difficult to burn. When the temperature is excessively low, the organic matter is not sufficiently combusted. On the other hand, when the temperature is excessively high, overcombustion occurs, and calcium oxide is easily generated by decomposition of calcium carbonate. In addition, when the in-furnace combustion temperature is 500 ° C. or higher, drying / combustion proceeds locally faster than the grain alignment of the dehydrated material 10 having various properties such as hard and soft, so that the particle surface and the interior of the particle It is difficult to make the difference in unburned ratio with a small uniform. Hot air is blown from a hot air generating furnace 20 provided with a burner 20A.

  From the exhaust gas chamber 16, exhaust gas subjected to drying and combustion is sent into the recombustion chamber 22. The fine powder contained in the exhaust gas is discharged from the lower part of the exhaust gas chamber 16 and is mixed with the raw material 10 again and reused. The exhaust gas is recombusted by a burner or the like in the recombustion chamber 22, precooled by the precooler 24, passed through the heat exchanger 26, and discharged from the chimney 30 by the induction fan 28.

  Here, the heat exchanger 26 raises the temperature of the outside air, and the raised outside air is sent to the hot air generation furnace 20 and blown into the internal heat kiln furnace 14. That is, the heat exchanger 26 recovers the heat of the exhaust gas from the exhaust gas chamber 16. The treatment of exhaust gas is effective for removing harmful substances contained in the exhaust gas.

  The first combustion furnace 14 slowly burns an easily combusted organic substance contained in the dehydrated product 10 and suppresses the generation of residual carbon, so that the residence (combustion) time is 30 minutes to 90 minutes under the above conditions. It is preferable to burn. If the combustion time is less than 30 minutes, sufficient combustion is not performed and the proportion of remaining carbon increases. On the other hand, when the combustion time exceeds 90 minutes, thermal decomposition of calcium carbonate occurs due to overcombustion of the raw material 10, and the obtained regenerated particles become extremely hard. From the viewpoint of combustion of organic matter and production efficiency, it is preferable to burn with a residence time of 40 minutes to 80 minutes. In order to ensure constant quality, it is preferable to burn with a residence time of 50 minutes to 70 minutes.

  Moreover, it is preferable to perform the drying and combustion of this process so that the unburned rate of the combustion substance supplied to the 2nd combustion process mentioned later may be 2-20 mass%, and it may become 5-17 mass%. It is more preferable to perform, and it is especially preferable to perform it so that it may become 7-12 mass%. By performing drying and combustion so that the unburned rate becomes 2 to 20% by mass, combustion in the second combustion step can be performed efficiently in a short time, and stable heating in the second combustion step Thus, it is possible to obtain a high whiteness combustion product having a low hardness and a whiteness of usually 80% or more and at least 70% or more. If drying and combustion are performed so that the unburned rate is less than 2% by mass, the energy cost in the first combustion furnace 14 becomes high, and the hardness of the combustion product may be increased. There is a risk of quality deterioration such as reduced whiteness of the burned material.

[Second combustion process] (Combustion process)
Combustion products dried and burned in the internal heat kiln furnace 14 are charged into an external heat kiln furnace 32 corresponding to a second combustion furnace having an external heat jacket 31 whose body is placed horizontally and rotates around the central axis through a transfer flow path or the like. To do.

  In the external heat kiln furnace 32, the combustion product is heated by external heat and controlled by the lifter provided on the inner wall of the kiln furnace to control the conveyance of the combustion product in the combustion furnace, thereby further slowly burning it. To burn the unburned part.

  In the combustion in the second combustion furnace 32, particles that are smaller than the particle diameter of the raw material 10 supplied to the first combustion furnace 14 in order to combust residual organic matter, for example, residual carbon, that could not be combusted in the first combustion furnace 14. It is preferable to use a combustion product adjusted to a diameter. The particle size of the burned product after the drying / combustion step is preferably adjusted to be an average particle size of 10 mm or less, more preferably adjusted to an average particle size of 1 to 8 mm, and an average particle size of 1 to 1 mm. It is particularly preferable to adjust to 5 mm. If the average particle diameter at the inlet of the second combustion furnace 32 is less than 1 mm, there is a risk of overcombustion. If the average particle diameter exceeds 10 mm, the remaining carbon is difficult to burn, and the regenerated particles can be obtained without progressing to the core. There is a risk that the whiteness of.

  Moreover, in order to ensure stable production in the second combustion furnace 32, it is preferable to adjust the particle diameter so that the combustion product having an average particle diameter of 1 to 8 mm is 70% or more. Such adjustment is beneficial to the possibility of practical use in terms of uniforming the quality of the obtained regenerated particles. In addition, when classification (adjustment of particle size) is performed after drying and combustion in this way, combustion products having a small particle size can be reliably removed, and the processing efficiency is also improved.

  As an external heat source of the external heat kiln furnace 32, an electric heating type heat source that is easy to control the temperature in the external heat kiln furnace 32 and easy to control the temperature in the longitudinal direction is preferable. A kiln furnace 32 is preferred. By using electricity as an external heat source, the temperature in the furnace can be finely and uniformly controlled, and control of the degree of combustion of combustibles with various properties such as formation of aggregates, hard and soft, Grain alignment can be performed stably. Further, the electric furnace can be provided with a temperature gradient arbitrarily by providing a plurality of electric heaters in the flow direction of the furnace, and can maintain the temperature of the combustion product at a constant temperature for a certain period of time. Residual organic components in the combustion product that has passed through the one combustion furnace 14, particularly residual carbon, can be brought to zero as much as possible without causing decomposition of the calcium carbonate in the second combustion furnace 32, and is lower than, for example, heavy calcium carbonate Regenerated particles with high whiteness can be obtained with a wire wear degree.

  In the external heat kiln furnace 32, oxygen concentration is adjusted to 5% to 20%, preferably 10% to 20%, more preferably 10% by using an air or oxygen supply mechanism (not shown) for adjusting the oxygen concentration. It is desirable to make it from 15% to 15%. If the oxygen concentration in the external heat kiln furnace 32 is less than 5%, there is a possibility that the combustion of the remaining carbon that is difficult to burn does not proceed.

  The combustion temperature in the external heat kiln furnace 32 is preferably 550 ° C to 780 ° C, more preferably 600 ° C to 750 ° C. As described above, in the second combustion furnace 32, it is necessary to burn the remaining organic matter that has not been burned in the first combustion furnace 14, particularly the remaining carbon, so that the second combustion furnace 32 is burned at a higher temperature than the first combustion furnace 14. When the combustion temperature is less than 550 ° C., there is a possibility that the residual organic matter cannot be sufficiently burned. On the other hand, when the combustion temperature exceeds 780 ° C., the oxidation of calcium carbonate in the combustion product proceeds, Particles may become hard.

  The residence (combustion) time in the external heat kiln furnace 32 is preferably 60 minutes or more, more preferably 60 minutes to 240 minutes, particularly preferably 90 minutes to 150 minutes, and most preferably 120 minutes to 150 minutes. Desirable for complete combustion. In particular, the remaining carbon must be burnt slowly at a high temperature that does not cause the decomposition of calcium carbonate as much as possible. If the residence time is less than 60 minutes, the remaining carbon is burnt in a short time, If the residence time exceeds 240 minutes, the calcium carbonate may be decomposed. In addition, when performing stable production of combustion products, it is preferable that the residence time is 60 minutes or longer, and in order to prevent overburning and secure productivity, the residence time is 240 minutes or less.

  It is suitable that the average particle size of the combustion product discharged from the external heat kiln furnace 32 is adjusted to 10 mm or less, preferably 1 mm to 8 mm, more preferably 1 mm to 4 mm. This adjustment can be performed, for example, by passing the combusted material between two rotating rolls having a certain clearance.

  The combusted material that has undergone the second combustion process is preferably an aggregate, cooled by the cooler 34, and then sorted by a particle size sorter 36 such as a vibration sieve, and a pulverization process using a wet pulverizer or the like After being adjusted to the desired particle size, the particles are temporarily stored in the combustion product silo 38 and are used as regenerated particles for applications such as pigments and fillers.

  In addition, although the case where the deinking floss was used as a raw material was illustrated above, the deinking floss was used as a raw material, and the raw material was appropriately mixed with other papermaking sludge such as paper sludge in the papermaking process. You can also.

[Slurry process]
The regenerated particles obtained through the above dehydration step, drying / combustion step, combustion step and the like are preferably suspended in water to form a slurry of regenerated particles.
The regenerated particles are preferably pulverized while being dissolved in water using a mixer or the like in order to achieve effective pulverization in the pulverization step which is a subsequent step. 50%, preferably 20 to 40%. In this slurry, calcium sulfate dihydrate is mixed with powdered regenerated particles or dissolved simultaneously with calcium sulfate dihydrate. It is preferable to mix things. When calcium sulfate dihydrate or the like is added after slurrying the regenerated particles, the curing reaction of the hydrated cured substance has already started, and the effect of suppressing the curing reaction of the hydrated cured substance cannot be obtained or is effective May decrease. Further, by containing calcium sulfate, the combustion product (regenerated particles) can be dissolved in water very uniformly.

  It is preferable that calcium sulfate dihydrate is contained in an amount of 0.5 to 10 parts by mass with respect to 100 parts by mass of the combustion product (regenerated particles). When the calcium sulfate dihydrate is less than 0.5 parts by mass, the contact probability with the hydrated cured substance is low, and the curing reaction suppressing effect may not be obtained. On the other hand, even if it exceeds 10 mass parts, there exists a possibility that the hardening reaction inhibitory effect may reach a peak. The content of calcium sulfate is more preferably 2 to 7 parts by mass in terms of quality and operability. The regenerated particle slurry dissolved in water is finely divided by a pulverizer or the like according to the use, and the particle size is adjusted.

  In addition to being able to purchase and use commercially available calcium sulfate, calcium sulfate dihydrate can also be used by reacting with calcium chloride and dilute sulfuric acid used in paper mills and the like. it can. This is possible because calcium sulfate dihydrate is formed and precipitated when calcium chloride is dissolved in water and diluted sulfuric acid is added.

  Moreover, the waste gypsum board currently processed as industrial waste can also be collect | recovered and utilized. Although it is preferable to use a waste gypsum board from the viewpoint of resource circulation, it can be appropriately selected in consideration of cost and the like.

[Crushing process]
In the method for producing regenerated particles of this embodiment, using a known dispersion / pulverization apparatus or the like, the regenerated particles are appropriately finely granulated to a necessary particle size, thereby providing a pigment for coating and a filler for internal addition. It can be preferably used.

  The regenerated particles having a concentration of preferably 15 to 50% that have passed through the combustion step and the slurrying step are preferably finely divided by a pulverizer. The average particle diameter of the regenerated fine particles is preferably 0.1 μm to 10.0 μm, more preferably 0.3 μm to 5.0 μm, and particularly preferably 0.5 μm to 2.0 μm. If the average particle size is less than 0.1 μm, the hydrated hardened substance such as calcium aluminate in the regenerated particles may be exposed, and the slurry may be agglomerated, and the specific surface area may be increased. In pigment applications, an excessive amount of binder component in the paint is required, which increases the cost and reduces the strength of the coating layer, which may affect the quality of the coated paper produced, such as the occurrence of paper dust. There is. On the other hand, when the average particle size exceeds 10.0 μm, the particle size distribution shows a broad peak, and the glossiness of the coated paper surface is reduced in coating pigment applications, resulting in deterioration in quality such as appearance during printing. There is a risk of connection.

  The particle size of the regenerated particles after the pulverization step is a volume average particle size measured by a particle size distribution measuring device (laser type microtrack particle size analyzer: manufactured by Nikkiso).

[Other processes]
Since the obtained regenerated particle slurry exhibits an alkalinity with a pH of 12 or more as it is, and may react with other chemicals in the coating liquid adjusting step in the coating pigment application, the quality may be deteriorated. In order to return the calcium oxide to calcium carbonate and reduce the pH, it is preferable to adjust the pH to, for example, 9 to 11 using carbon dioxide in the exhaust gas discharged in the drying / combustion process or the combustion process. For this pH adjustment, not only exhaust gas but also commercially available carbon dioxide gas can be used and used in combination.

  The slurry whose pH adjustment has been completed is sent to the dispersion step. As the dispersing device, for example, a mixer, a coreless disperser, a ball mill and the like can be appropriately selected and used. The concentration of the regenerated particles at this time is 50 to 70% by mass, preferably 55 to 70% by mass, and more preferably 60 to 65% by mass. When the slurry concentration is less than 50% by mass, for example, the concentration of the coating liquid in the application of the coating pigment is reduced, the effect of the aggregation inhibitor is reduced, the precipitation of the particles in the regenerated particle slurry, and the like. There is a risk that the quality stability of the product will deteriorate. On the other hand, if the slurry concentration exceeds 70% by mass, the slurry may be thickened and solidified, and an increase in energy required for dehydration becomes a problem.

  In this embodiment, in order to further stabilize the quality of the regenerated particles, it is preferable to classify the particle diameter of the object to be processed uniformly in each process, and feed back coarse and fine particles to the previous process. By doing so, quality can be further stabilized.

  In addition, it is preferable to granulate the deinked floss (dehydrated product) that has been subjected to dehydration in the previous stage of the drying process, and it is more preferable to classify the granulated product to make the particle size uniform. The quality can be further stabilized by feeding back coarse or fine granulated particles to the previous process. In granulation, known granulation equipment can be used, but equipment such as a rotary type, a stirring type, and an extrusion type is suitable.

  As raw materials in the production method of the present embodiment, it is preferable to remove in advance those that can be used as raw materials for regenerated particles. It is preferable in terms of removal efficiency to remove sand, plastic foreign matter, metal and the like. In particular, iron contamination is a causative agent for reducing the whiteness of fine particles due to oxidation, so it is recommended to avoid iron contamination and selectively remove it. Design or lining each process with materials other than iron, It is preferable to prevent iron from being mixed into the system due to abrasion or the like, and to selectively remove iron by installing a high magnetic material such as a magnet in a drying / classifying facility or the like.

  The regenerated particles produced by the method for producing regenerated particles according to the present embodiment have a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxide in the elemental analysis of fine particles by an X-ray microanalyzer. It is preferably a ratio, more preferably a mass ratio of 40 to 82: 9 to 30: 9 to 30, and particularly preferably a mass ratio of 60 to 82: 9 to 20: 9 to 20. By including calcium, silica, and aluminum in a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxides, the specific gravity is light and excessive aqueous solution absorption can be suppressed, so that the dehydrating ability in the dehydration process can be reduced. It is good and can reduce the proportion of unburned matter in the drying / combustion process and the risk of excessive hardness due to sintering in the combustion process.

  As a method of adjusting the mass ratio of calcium, silica, and aluminum, the main ingredient is to adjust the raw material composition in the deinking floss, but in the drying / combustion process and combustion process, the coating floss and preparation with a clear source are used. It is also possible to adjust by means for containing the process froth in the process by spraying or the like, or means for containing the incinerator scrubber lime. For example, using deinked floss as the main raw material, neutral papermaking drainage sludge and wastewater sludge from the coated paper manufacturing process are used to adjust calcium in the regenerated particles, and opacity improvers are used to adjust silica. Newspaper manufacturing wastewater sludge with a large amount of white carbon added, papermaking wastewater sludge that uses an acid papermaking system and other sulfuric acid bands to adjust aluminum, and high-quality papermaking process that uses a lot of clay Drainage sludge in can be used.

  In addition, the regenerated particles produced by the method for producing regenerated particles according to the present embodiment are measured by using a differential thermothermal gravimetric simultaneous measurement apparatus (manufactured by SII Nano Technology Co., Ltd. (model TG / DTA6200)), and measuring conditions are as follows: 25-1050 ° C .: 20 ° C./min, (2) Supply gas: air (oxygen concentration about 5 vol%), (3) Supply gas flow rate: Generated at around 700 ° C. in differential thermal analysis measured at about 48 ml / min By controlling combustion of the workpiece so that the weight loss (rate) in decomposition of calcium carbonate (change to calcium oxide) is 50% or more, the progress of oxidation of the calcium component is more accurately suppressed, and the particles It can prevent becoming hard.

(Second lifter 32 lifter (weir))
As described above together with the reason for adoption, a spiral lifter and / or a parallel lifter parallel to the axis is disposed on the inner wall of the second combustion furnace 32 from one end side to the other end side. Thus, uniform combustion of the raw material (combustible material) and uniform quality can be achieved.

  And it is desirable to arrange | position a helical lifter and a parallel lifter parallel to an axial center in this order especially toward the discharge side from the charging side of a to-be-combusted object. According to this configuration, while the combusted material thrown in from the charging side is first lifted and dropped while being fed in an appropriate amount toward the other end side by the spiral lifter, To make efficient contact with the combustion gas (combustible gas) by contacting the combustion gas (combustible gas) generated by gasification efficiently and then repeatedly lifting and dropping by the parallel lifter The combustible can be combusted with high heat exchange efficiency. In particular, by controlling the amount of combusted material sent to the parallel lifter by the spiral lifter, the combusted material is properly lifted and dropped at the parallel lifter part, and the combustion of the combusted material is uniform and efficient. Can be done automatically. Further, since there is no fear of damage to the refractory, there is no decrease in the purity of the combusted material, and its production capacity is improved.

  In addition, when the spiral lifter and the parallel lifter are made of metal such as a stainless steel plate having heat resistance, for example, since the temperature is relatively low, sufficient durability and strength can be secured without using an expensive heat-resistant material, Since the heat transfer efficiency is higher than that of a refractory lifter, the heat efficiency can be further improved.

  The above embodiment will be described with reference to FIG. 2. In FIG. 2, the combusted material is inserted from the left side of the second combustion furnace 32 and is configured to be rotationally driven by a rotational drive means (not shown). And discharged from the other end side.

  The second combustion furnace 32 is configured by lining a fireproof wall 32B made of fireproof castable or fireproof brick on the inner surface of a cylindrical outer casing 32A. On the inner surface of the refractory wall 32B of the second combustion furnace 32, a plurality of strips (in the illustrated example) are inclined at an inclination angle of 45 to 70 with respect to the axis of the second combustion furnace 32 on the charging (charging) side. 8) spiral lifters 4 project at equal intervals, and further, parallel lifters 5A of an appropriate length parallel to the axis of the second combustion furnace 32 are provided on the other end side of the region where the spiral lifters 4 are disposed. Are arranged in a zigzag manner in a plurality of rows (eight in the illustrated example) in the circumferential direction and in a plurality of rows (eight in the illustrated example) in the axial direction.

  The parallel lifter 5A is continuously formed on the right side of the drawing toward the discharge portion (not shown). In this case, since the temperature is low on the charging side, it is desirable to form a heat-resistant and corrosion-resistant metal plate such as a stainless steel plate, and the discharge side is relatively high temperature. The lifter 5A can be made of a refractory material.

  In this embodiment, the helical lifter 4 is fixedly disposed on the mounting brackets 6 disposed at appropriate intervals in the longitudinal direction. Further, each parallel lifter 5A is fixedly disposed on each mounting bracket 5B. If necessary, only one of the spiral lifter and the parallel lifter may be provided.

[Coating layer]
Next, the preparation process of a coating liquid is demonstrated.
In the present embodiment, the ratio of the pigment composed of regenerated particles to the pigment constituting the coating layer is such that the coating layer is a single layer, a multilayer, or a pigment composed of regenerated particles anywhere in the multilayer coating layer. Or can be appropriately adjusted according to the target quality of the target coated paper, and is not particularly limited. However, in order to obtain a coated paper with high opacity which is an object of the present invention, 10% by weight or more, preferably 20% by weight or more of the total pigment constituting the coating layer is a pigment composed of regenerated particles. It is desirable to blend as such. Further, the upper limit of the ratio of the pigment composed of regenerated particles can be, for example, 100% by weight when blended in the undercoat coating layer, while the outermost layer of the single layer coating layer or the multilayer coating layer. When blending pigments composed of regenerated particles, considering the quality such as opacity and whiteness of the coated paper, 50% by weight or less of the total pigment constituting the coating layer is composed of regenerated particles. It is preferable to blend so that.

  Examples of pigments that can be used in combination with pigments composed of recycled particles include kaolin, clay, calcium carbonate, aluminum hydroxide, zinc oxide, barium sulfate, calcium sulfate, silica, activated clay, Examples thereof include inorganic pigments such as talc, satin white and lake, and organic pigments such as plastic pigments. At this time, by blending so that the absolute value of the difference between the whiteness of the base paper and the whiteness of all pigments constituting the coating layer containing the pigment composed of regenerated particles is within 10 points, high opacity is achieved. A coated paper with little unevenness in whiteness can be obtained.

  The coated paper in the present invention includes newsprint. The whiteness of newsprint is generally about 50%, but the opacity of newsprint reduced in weight is required to be 90% or more. Accordingly, as a countermeasure against the opacity of such newspaper paper, a processing layer (coating layer) mainly composed of a pigment composed of recycled particles and an adhesive can be provided on the newspaper base paper. In newsprint paper, opacity is the most important paper quality, so the difference between the whiteness of the base paper and the whiteness of all the pigments constituting the coating layer may not fall within the range of ± 10 points.

  In the coated paper for printing of the present invention, the adhesive used together with the pigment is not particularly limited. For example, proteins such as casein, soy protein, and synthetic protein: styrene / butadiene copolymer, etc. Conjugated diene polymer latex, acrylic polymer latex such as acrylic acid ester and / or methacrylic acid ester polymer / or copolymerization, vinyl polymer latex such as ethylene / vinyl acetate copolymer, or various kinds of these Alkali-soluble or alkali-insoluble polymer latex modified with a functional group-containing monomer such as carboxyl group: Synthetic resin adhesive such as polyvinyl alcohol, olefin / maleic anhydride resin, melamine resin: positive starch , Oxidized starch, enzyme modified starch, thermochemically modified starch, etherified starch, esterified starch , Starches such as cold water soluble starch: carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, adhesives for ordinary coated paper may be appropriately selected and used.

  The blending ratio of the adhesive is about 5 to 25 parts by weight, more preferably about 10 to 20 parts by weight with respect to 100 parts by weight of the pigment in terms of solid content. In the pigment coating composition, a dispersant, a thickener, a water retention agent, a flow modifier, a defoaming agent, a release agent, a water-resistant lubricant, a bluing agent, an antiseptic, a lubricant, Various auxiliaries such as dyes and pH adjusting agents can be appropriately blended.

  In the coated paper for printing of the present invention, particularly when a pigment composed of regenerated particles is used in the coating layer as the outermost layer, the fluorescent dye is 0.3 to 3.0 with respect to the pigment composed of regenerated particles. It is preferable to add by weight.

  Such a fluorescent dye absorbs light in the vicinity of 340 to 380 nm and emits fluorescence in the visible part near 430 to 440 nm to increase the whiteness of the coated paper. Specifically, the following compound systems can be exemplified. These may be used alone or in combination of two or more. 4,4′-bis (4,6-disubstituted-1,3,5-triazinyl-2-amino) stilbene-disulfonic acid, α, β-bis (benzoxazolyl) ethylene, alkoxynaphthalic acid An organic compound having a structure such as an -N-substituted imide, benzoxazole, coumarin, or thiophene can be given.

  In the present invention, as described above, it is also possible to form two or more pigment coating layers on one side of a base paper, and it is possible to impart functions such as smoothness, gloss and print ink acceptability to the coating layer. Therefore, it is preferable to form two or more (usually two) coating layers. It is also possible to form coating layers on both sides of the base paper. At this time, a pigment made of regenerated particles may be added to any layer. In the present invention, it is preferable that the whiteness of the pigment made of the regenerated particles to be used does not fall below 60%. However, when the whiteness is lower than this, this can be achieved by adding a fluorescent dye. This is because it is difficult to obtain a coated paper for printing having the following. The fluorescent dye can be divided and added to each paint of the multilayer coating.

  The solid content concentration of the paint for forming the pigment coating layer is generally about 40 to 75% by weight, but is preferably in the range of 45 to 70% by weight in consideration of operability.

  Paints prepared under the above conditions are, for example, blade coaters, air knife coaters, roll coaters, reverse roll coaters, bar coater curtain coaters, dice rod coaters, gravure coaters, champlex coaters, gate roll coaters, size presses, etc. Coating is performed by an on-machine or an off-coater provided with a coating apparatus. When finishing a coated paper with high glossiness, it is preferable to employ a blade coater, a rod blade coater or the like.

The coating amount of the paint on the base paper can be appropriately adjusted in a range of about ² to 50 g / m ² per side in terms of dry weight. In addition, this coating amount is a total coating amount including multilayer coating. The pigment coating layer is dried and then finished through a finishing device such as a super calender or a gloss calender.

〔Base paper〕
Waste paper pulp can be used as a pulp raw material constituting the base paper, and examples of the raw material waste paper include newspaper waste paper, printing waste paper, magazine waste paper, and OA waste paper. In addition, virgin pulp can also be used, and there is no restriction on hardwood and softwood, and pulp obtained from both raw materials can be arbitrarily blended. In addition, in this pulp manufacturing method, kraft pulp (KP) and sulfite pulp (SP), which are chemical pulping methods that are delignified by cooking liquor, and ground wood pulp (GP) that is mechanically ground. Refiner pulp, groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), chemiground pulp (CGP), semi-chemical pulp (SCP), or any other mechanical pulping method may be used. It should be noted that when used paper pulp is blended, the blending ratio can be arbitrarily determined, but the absolute difference between the whiteness of the base paper and the whiteness of all the pigments constituting the coating layer containing the pigment made of recycled particles. It is desirable to blend so that the value is within 10 points in order to obtain a coated paper having no whiteness unevenness.

  In general, as a method of producing deinked pulp from waste paper, (printing) waste paper disaggregation process, alkali soaking (alkali soaking) process, flotation process, washing process are appropriately combined to treat pulp and ink. Yes. In this embodiment, it is preferable to use enzyme beaten pulp that has been further subjected to enzyme beating in such a deinking step.

  Enzymatic beating treatment includes a complex enzyme containing a complex cellulase containing endoglucanase, cellobiohydrolase and β-glucosidase as an enzyme, and a hemicellulase containing xylanase. Increase the strength between.

  It has been introduced as a conventional technique that enzymes used in conventional waste paper pulp are added particularly in a flotation facility in the deinking process for the purpose of improving the deinking efficiency in the deinking process.

  The present inventors decompose the cellulose structure on the surface of the pulp fiber with an enzyme and apply an enzyme treatment that makes the pulp fiber surface fluffy, in particular, a feed pump facility for the papermaking process after the deinking process or By adding to the stock tank in front of the inflow pump, it was found that pulp fibers can be efficiently fluffed and the strength improvement effect of waste paper pulp can be obtained, and one end of this embodiment could be configured. is there.

  In particular, unlike enzymes used in conventional deinking processes, endoglucanase is capable of performing slow and long-lasting cellulose degradation, although the reason is not clear in enzyme beating in a feed pump or stock tank. We have found that a complex enzyme comprising a cellulase containing cellobiohydrolase and β-glucosidase and a hemicellulase containing xylanase is most preferred.

  Furthermore, due to the diligent study of the present inventors, it is included in the waste paper by adding an enzyme to the target pulp in at least one of the stock process and the transport process, which is a process before the waste paper pulp is completed in the waste paper pulp manufacturing process. And a method for producing waste paper pulp that can stably improve pulp strength without being affected by mechanical pulp, anionic substances, suspended colloidal substances, and the like.

  Here, the temperature of the target pulp when the enzyme is added is preferably 30 to 55 ° C, and more preferably 40 to 50 ° C. In the case of a normal chemical reaction, the higher the temperature, the more active it is. However, in the case of an enzyme, when the temperature exceeds 55 ° C. which is the upper limit of the optimum temperature, heat denaturation occurs and the activity is lost. If the temperature of the target pulp at the time of adding an enzyme is less than 30 ° C., the enzyme hardly exhibits a reaction activity, and thus the effect of improving the pulp strength by adding the enzyme cannot be obtained.

  Moreover, the pH of the object pulp at the time of adding an enzyme is 5.5-8.5 normally, Preferably it is 6.7-8.0. Below pH 5.5 or above pH 8.5, the three-dimensional structure of the enzyme active site is changed, and the connection with the substrate (cellulose in fibers, hemicellulose) is reduced, and the effect of enzyme addition is reduced. On the other hand, when the pH exceeds 8.5, when the used waste paper pulp is used as a raw material pulp, the drainage is lowered, the dehydrating property is deteriorated and the operability is lowered. In some cases, the effect of the coagulant may be impaired. Further, when the pH is lower than 5.5, the calcium carbonate contained in the waste paper pulp is decomposed, and the problem of scale generation due to the generation of carbon dioxide and the expression of calcium hydroxide occurs. It may cause an effect inhibition.

  In this embodiment, the amount of the enzyme added is preferably 10 to 1000 ppm by weight, more preferably 25 to 500 ppm by weight. If the addition amount is less than 10 ppm by mass, the effect may not be obtained. On the other hand, if the addition amount exceeds 1000 ppm by mass, there is little improvement in the effect, it is uneconomical, and there is a possibility that the system may become dirty. .

  Furthermore, as the enzyme, endoglucanase (EG) that randomly cleaves amorphous cellulose (hydrated cellulose) swollen with water, cellobiohydrolase (CBHI), EG, CBHI, which sequentially cleaves from the non-reducing end of crystalline cellulose, It is preferable to use a complex enzyme containing a complex cellulase containing β-glucosidase that decomposes the cellooligosaccharide cleaved by II into a monosaccharide and a hemicellulase containing xylanase. Since this complex enzyme has a slow production rate to decompose to a monosaccharide, it can stably modify the cellulose fiber without reducing the mechanical strength of the fiber. Can be expected. When an enzyme is added to the pulp, fine fibrillation (fluffing) occurs in the cell wall of the fiber, and the enzyme selectively acts on the fiber fibrils generated by physical shearing forces such as the disaggregation process and dust removal process. It is considered that the effect of fibrillation in a microscopic state is developed even for the waste paper pulp fiber that acts and is repeatedly and repeatedly brittle while maintaining the fibril state generated in the fiber wall. And since this fibrillated fine fiber has a wide specific surface area, the number of hydrogen bonds inevitably increases, and the bond between fibers becomes stronger when it becomes paper, resulting in excellent adhesion performance, increasing the bond area between fibers, Mechanical strength is improved by increasing the density of paper. In addition, fibrillation can be produced even for long fibers that are difficult to receive physical shearing force, and fine fibers adhere to each other, so that it is possible to improve the pulp strength of the obtained waste paper pulp.

  In general, an enzyme has a substrate specificity that only reacts with one substrate and a reaction specificity that is limited to only one reaction and does not cause other side reactions. Therefore, in the preferred production method of this embodiment, a complex enzyme is used. Further, according to the knowledge of the present inventors, a complex cellulase containing endoglucanase, cellobiohydrolase, and β-glucosidase, and xylanase are used. By using a complex enzyme that contains hemicellulase, it reacts only with cellulose and hemicellulose, and has a property that it is difficult to react with other chemicals such as sizing agent and pulp strength agent, so sizing agent and pulp strength agent There is no risk of inhibiting the effects of other chemicals.

  Moreover, since the complex enzyme is a nonionic substance and does not contain a surfactant, inorganic ions, or the like, there is no possibility of affecting the performance of the rosin sizing agent. Conversely, by adding the above complex enzyme, there is a possibility that the amount of rosin sizing agent used can be reduced, and even with waste paper pulp that has a high ash content derived from waste paper, waste paper pulp with high pulp strength and high whiteness It has the potential to be obtained.

  When using the complex enzyme as an enzyme, it is more preferable that the component content of each enzyme used in the complex enzyme is 20% (vs. total enzyme mass) or less. This is because the heavy use of the enzyme leads to the cutting of cellulose constituting the pulp fiber, which leads to the refinement of the pulp fiber and the decrease in the pulp strength.

  In the method for producing waste paper pulp of this embodiment, waste paper is disaggregated by a pulper in a disaggregation step to obtain pulp slurry. This pulp slurry is dedusted with a screen in the dust removal process, and after adding a deinking agent such as higher alcohol and fatty acid in the deinking process, the ink is floated and separated by a flotation process using a flotator, and then carefully selected. After selecting carefully with a cleaner in the process, bleach and alkali soaking in an alkali soaking tower after adding bleaching agents such as hydrogen peroxide and formamidinesulfinic acid, buffering agents such as sodium silicate and alkaline chemicals such as caustic soda in the bleaching process In the subsequent deinking step, the ink is subjected to a flotation process by a floatator to separate and remove.

  Subsequent to these steps, in the washing step and the dehydration step, washing and dehydration are performed while supplying water as a washing liquid by a dehydrator, and the obtained dehydrated pulp is sent to a stock tower provided in the stock step. Dehydrated pulp is charged from the stock tower, and the charged dehydrated pulp is diluted with diluted water to form a slurry. The diluted pulp slurry is fed to a paper making process (not shown) through a conveying process. In the present embodiment, the conveying step includes a pipe line through which the diluted pulp slurry from the stock tower is fed, and a flow for feeding the diluted pulp slurry provided in the middle of the pipe line. It is equipped with a feed pump.

  Here, in the method for producing waste paper pulp of this embodiment, an enzyme is added to the pulp in at least one of the stock process and the transport process. There are various places where this enzyme can be added. Typically, the form is added to the upper part of the stock tower, the form is added to the lower part of the stock tower by passing the pipe, etc. A single type or a combination of forms added to the pipe line upstream of the feed pump, for example, by passing it through is considered. For example, when it is desired to grasp the pulp strength in a timely manner and optimize the addition amount, a mode with a small time lag with the papermaking process is preferable.

  The pulp concentration when the enzyme is added at a stage where the pulp concentration is high is preferably adjusted to 15 to 35%, more preferably 20 to 30% by a dehydrator. If the pulp concentration is less than 15%, the added enzyme may be diluted, and the effect of the enzyme addition may be difficult to express. Thus, it is necessary to add a relatively large amount of enzyme to the pulp raw material. However, if a large amount of enzyme is added, there may be a problem that quality variation is likely to occur, for example, the strength of the pulp may be reduced. On the other hand, when the pulp concentration exceeds 35%, uniform dispersion and reaction between the pulp and the enzyme are difficult to occur, and the pulp strength may be uneven.

  On the other hand, the pulp concentration when the enzyme is added at a stage where the pulp concentration is low is preferably 2.5 to 5.0%, more preferably 3.0 to 4.4 by adjusting the amount of dilution water. Adjust to 5%. If the pulp concentration is less than 2.5%, the effect of the enzyme is hardly exhibited, and the workability in the paper making process may be reduced due to a decrease in the feed concentration of the raw pulp. On the other hand, when the pulp concentration exceeds 5.0%, the contact reaction between the enzyme and the pulp is inhibited, and there is a possibility that unevenness in the effect of improving the pulp strength may occur, and the fibrillated fibers easily fall off. It becomes a factor of decline.

  The reaction time between the enzyme and the target pulp is preferably 0.3 to 2.5 hours, more preferably 0.5 to 2.0 hours. If the time is less than 0.3 hours, the reaction may not proceed sufficiently. On the other hand, if the time exceeds 2.5 hours, the reaction proceeds excessively, which may lead to a decrease in pulp strength.

  In this embodiment, the used paper is a used paper product, which is general paperboard, paper, cutting waste of paperboard, and the like, and includes waste paper, but usually used paper is mainly used.

  As described above, in the present embodiment, the used paper pulp that has undergone the disaggregation process, the dust removal process, the deinking process, the bleaching process, the washing process, the dehydration process, the stock process, and the transport process is used for the papermaking process. And, in at least one of the stock process and the transport process before being subjected to the papermaking process, when an enzyme is added from the enzyme tank to the pulp (dehydrated pulp) in the stock tank or to the pulp (usually pulp slurry) being transported Is preferred.

  As fillers for the base paper used in this embodiment, heavy calcium carbonate, light calcium carbonate, talc, clay, kaolin, titanium dioxide, synthetic silica, aluminum hydroxide and other inorganic fillers used in normal paper production, polystyrene resin In addition, synthetic polymer fine particles such as urea formaldehyde resin can be appropriately selected and used, but a pigment made of regenerated particles used for the coating layer of this embodiment can also be used. Of course, two or more of these may be used in combination. The amount of filler added is preferably about 1 to 30% by weight with respect to the solid content of the total stock. Further, a paper strength enhancer, a sizing agent, a dye, a fluorescent dye, an antifoaming agent, a pitch control agent, a slime control agent, and the like can be appropriately added to the paper stock containing pulp and filler as necessary. .

A base paper is produced by making a paper with a known paper machine using such a stock. If necessary, a surface treatment agent such as starch can be size-pressed on the base paper. The basis weight of the base paper is not particularly limited, but normally, when a base paper having a basis weight of about 30 to 100 g / m ² is used, the desired effect of the present invention is remarkably exhibited. Of course, it is also possible to apply to cardboard such as card or paperboard exceeding this range.

Next, examples and comparative examples of the present invention are shown.
First, regenerated particles were produced under the conditions described in Tables 1 and 2. Table 1 and Table 2 also show the quality of the regenerated particles obtained.

  The measurement conditions and quality evaluation in the table were as follows.

(Unburnt rate)
After heating the electric muffle furnace to 600 ° C. in advance, the sample was put in a crucible and completely burned in about 3 hours, and the weight was calculated before and after combustion.
(Wire wear degree)
The measurement was performed at a plastic wire wear degree (manufactured by Nippon Filcon for 3 hours) and a slurry concentration of 2% by weight.
(productivity)
Evaluation of raw material dehydration efficiency, productivity, and power required for pulverization, with ◎ as the most efficient condition, ◯ as good, water efficiency, productivity, and pulverization △, and those that are difficult to operate are ×.
(Quality stability)
For each item of whiteness, particle diameter, and production amount at a fixed time interval of the fine particles obtained by a predetermined method, measure the degree of fluctuation, rank them in the order of the smallest fluctuation, and rank up to the top three. The 12th place from the rank was marked with ◯, the 13th to 14th place was marked with △, and the following was marked with x.
(Appearance)
The color of the regenerated particles was visually judged and classified.

  Next, a coated paper was produced using the regenerated particles. Production conditions and physical properties of the obtained coated paper are shown in Tables 3 and 4.

  The production conditions and evaluation methods in the table were as follows.

<Paper pulp>
Mixed waste paper including newspapers and leaflets was disaggregated in advance. An example of the disaggregation equipment used in the disaggregation process is a pulper. There is no particular limitation on the pulper, and any structure can be used. For example, the raw material and water are put into the tab, and the tab is disaggregated by the stirring force of the rotor provided at the bottom or side of the tab. The type pulper is preferable, the tab type low concentration pulper (treatment concentration: 3.0 to 5.5% by mass), the tab type medium concentration pulper (treatment concentration: 5.5 to 13.0% by mass), the tab type high Any of the concentration pulpers (treatment concentration: 13.0 to 20.0 mass%) can be used. In addition, instead of the tab-type pulper, a drum-type pulper such as a horizontal drum-type pulper with excellent foreign matter discharge capability for the purpose of disaggregation at a higher concentration can also be used. It is not necessary to use a disintegration type pulper that applies a shearing force. Either a batch type pulper or a continuous type pulper can be used. In this example and comparative example, a batch type pulper was used.

  In the disaggregation treatment, the deinking agent is added at a temperature of 70 ° C. and the solid content in terms of pulp is caustic soda 0.8%, sodium silicate 2.5%, hydrogen peroxide 1.2%, and surfactant. 0.1%. Next, the disaggregated pulp taken out from the disaggregation treatment facility was diluted with dilution water, this diluted suspension was washed with a washing machine, and dehydrated to a concentration of 25% to obtain disaggregated pulp. Subsequently, the disaggregated pulp was diluted to a pulp concentration of 1%, put into a floater, and deinked.

  To the pulp after deinking, 2.0% caustic soda, 5.0% sodium silicate, 0.15% surfactant, and 1.5% hydrogen peroxide were sequentially added as the solid content in terms of pulp. Hydrogen peroxide bleaching was carried out at 10% in a hydrogen peroxide bleaching tower at 60 ° C. for 120 minutes. Enzymes were added to the obtained pulp after bleaching with hydrogen peroxide under the conditions described in the table to obtain enzyme beaten pulp.

<Base paper>
Next, the waste paper pulp obtained above and hardwood bleached pulp having a whiteness of 83% and an opacity of 78% (self-made LBKP) are blended in the proportions shown in Table 3, and further solid content in terms of pulp As shown in Table 3, paper containing a filler, a sizing agent (Fibran 81 / Oji National), cationized starch (Ace K100 / Oji Cornstarch), and an acrylic amide polymer (Himoloc NR12MLS / Himo) A base paper for coating having a basis weight of 48.0 g / m ² was produced using a long paper machine.

  In addition, about the kind of filler in a table | surface, a manufacture example shows the manufacture example number of Table 1 and Table 2, and uses as a heavy calcium carbonate (brand name; FMT-97, the product made from Pimatec). did.

<Coating liquid for pigment coating layer>
In the slurry which mix | blended the regenerated particle | grains after the grinding | pulverization process obtained by the said manufacturing method, light calcium carbonate, and clay in the ratio of Table 3, an oxidation starch (Ace A / Oji Cornstarch) is mix | blended ratio of Table 4 (Conversion in solid content) and styrene-butadiene copolymer latex (JSR-0613 / JSR) were added at a blending ratio (in solid content conversion) shown in Table 4 to obtain a coating solution.

<Coated paper for printing>
On the base paper for coating containing the above-mentioned waste paper pulp, the coating liquid for the pigment coating layer obtained above is coated on both sides with a desktop blade coater so that the coating amount shown in Table 4 per side is obtained in terms of dry solid content. And dried to obtain a coated paper for printing.

  “Basis weight” is a value measured in accordance with “Basis weight measurement method” described in JIS-P8124.

  “Hot water extraction pH” is a value measured based on “Test method for pH of paper, paperboard and pulp-water extract” described in JIS P 8133.

  “Whiteness (%)” is a value measured according to “Hunter Whiteness Test Method for Paper and Pulp” described in JIS-P8123.

  The “white paper opacity” is required to have high opacity from the point of being difficult to show through during printing, but was measured according to “Paper Opacity Test Method” described in JIS-P8138. Value.

“Print opacity” is a value obtained by the following method.
Using an RI printing suitability tester, printing was performed while changing the ink amount of black ink. The ratio of the back surface reflectance after printing with respect to the back surface reflectance before printing (the reflectance of the surface opposite to the printing surface) when the reflectance of the printed surface was 10% was determined based on the following formula. A spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd.) was used for the reflectance measurement.
Printing opacity (%) = (back surface reflectance after printing / back surface reflectance before printing) × 100

  The “opacity difference” is an absolute value of a difference between the printing opacity and the blank paper opacity.

  “Glossiness (%)” is a value measured based on a 75-degree specular gloss test method defined in JIS-P8142.

“Surface strength” refers to the coating layer per 10 cm ^{2 of} paper printed on the surface of a paper sample with an RI tester (manufactured by Meiko Seisakusho) using ink tack 6 (manufactured by Toyo Ink Manufacturing Co., Ltd.). The state is visually observed and scored. The evaluation criteria are “1” “There is considerable peeling of the coating layer”, “2” “There is peeling of the coating layer”, “3” “Slight peeling of the coating layer” , “4” “slightly peeled coating layer” and “5” “nearly peeled coating layer” were assigned to a five-step evaluation. The practical minimum grade is “3”.

  INDUSTRIAL APPLICABILITY The present invention can be applied as coated paper having a coating layer using deinked floss as a main raw material and regenerated particles obtained by a predetermined production method as a coating pigment.

  DESCRIPTION OF SYMBOLS 10 ... Raw material, 14 ... Internal heat kiln furnace (1st combustion furnace), 32 ... External heat (electric) kiln furnace (2nd combustion furnace).

Claims (5)

Using the deinked floss separated from the pulp fiber in the deinking process of the used paper processing equipment for manufacturing used paper pulp, the regenerated particles obtained by dehydrating, drying, burning and grinding the main material are used for coating. Coated paper having a coating layer used as a pigment of
The combustion process has at least two stages of combustion steps, including a first combustion furnace and a second combustion furnace after which the deinking floss burned in the first combustion furnace is burned again;
In the first combustion furnace, the combustion treatment is performed at 300 ° C. or higher and lower than 500 ° C.,
Coated paper characterized by that. The first combustion furnace is an internal heat kiln furnace in which the main body is placed horizontally and rotates around a central axis, and the moisture content of the raw material after the dehydration step is 40% or more,
The coated paper according to claim 1. Hot air of 300 ° C. or more and less than 500 ° C. is blown so that the oxygen concentration in the internal heat kiln furnace is 0.2% to 20%.
The coated paper according to claim 1 or 2. The second combustion furnace is an external heat kiln furnace in which a main body is placed horizontally and rotates around a central axis, and is parallel to a spiral lifter and an axial center on the inner wall of the kiln furnace from one end side to the other end side. At least one of the parallel lifters is disposed,
The coated paper of any one of Claims 1-3. As the raw material pulp of the coated paper base material, waste paper pulp is used as a main raw material, and the waste paper pulp is an enzyme-treated waste paper pulp obtained by enzymatic treatment with a complex enzyme.
The coated paper of any one of Claims 1-4.

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