JP4952539B2 - Coating liner and cardboard using the same - Google Patents

Description

  The present invention relates to a coating liner and corrugated cardboard using the same. In particular, it can be used as a liner for a cosmetic corrugated cardboard having excellent ink colorability in flexographic printing provided with a coating layer containing a regenerated pigment.

In general, the liner is a cardboard made of 3 to 9 layers, and used for the middle layer is waste paper pulp that is not deinked for the purpose of cost and resource saving. Liners are processed into cardboard sheets in combination with core base paper and used in various packaging boxes. However, in recent years, the function of cardboard boxes has only to be protected from physical forces that are received during the distribution process such as storage and transportation. In addition, many multi-color printing has been carried out in order to add a function as a product face so that the product can be seen on display or in a cellar with the product packed. For this reason, flexo printing, which has made remarkable technological progress compared to offset and gravure printing, is a recent wave of digitization in response to market issues such as the increase in variety of small lots, environmental and safety issues, and cost reduction. At the same time, it is attracting attention with its innovative and innovative technology. Furthermore, the print quality is comparable to other printing methods, and has a great advantage in terms of water-based and solvent-free. Flexo printing has already become mainstream in the packaging field in Europe and the United States. There are signs of dissemination. Under such circumstances, in addition to the usual craft colors, liners called makeup liners that perform attractive multi-colored printing are blended with bleached pulp and upper white waste paper pulp on the surface layer, or with white pigment paint. It was manufactured by coating and increasing the whiteness of the surface. Further, since measures for the surface layer alone are costly, pulp having a certain degree of whiteness may be used for the surface lower layer (layer immediately below the surface layer) to conceal the color of the intermediate layer. Those having such a high whiteness appearance give not only a blank paper surface but also an effect that the printed surface looks beautiful and vivid when printed on it. For this reason, corrugated cardboard boxes that have been color-printed using this type of liner have a high eye-catching effect, and in order to faithfully represent the contents, the contents are excellent. There is an excellent aspect that can appeal strongly. In recent years, it has become common to sell products packed in cardboard boxes at stores, mainly from mass retailers. From this point of view, a beautiful and vivid liner has been printed. It has been demanded.

  A liner that provides a calm visual effect with a deep white paper appearance and printed appearance by adjusting the whiteness and hue of the liner surface to a predetermined range is disclosed (see Patent Document 1). In addition, the coating layer containing various pigments and binders as the main components gives a calm visual effect on white paper by adjusting the whiteness, hue, and gloss to a specific range, and the printed characters are easy to read. A cosmetic liner is disclosed that has good ink colorability when printed in color, good print gloss, and a clear printed surface. However, all of these disclosures merely define the hue as a liner, and are not proposals that sufficiently satisfy the printability in flexographic printing. In addition, there is a method in which a large amount of white ink is printed on a general brown liner and then other colors are printed to add cosmetics. In this case, the surface of the brown liner is made white, red or indigo. In order to improve the finish of other color inks and the like, it is necessary to print a large amount of expensive white ink, and this method is also a large economical burden.

  Furthermore, as a method for obtaining a liner having excellent flexographic printability, a technique for improving the printing effect by applying a cationic resin to the liner surface is disclosed. (Refer to Patent Documents 3 and 4) However, the color development of the ink and the finish of the printed surface are not fully satisfactory.

Further, (a) 20 to 70 parts by weight of calcined kaolin (b) structured kaolin as a pigment composition in the aqueous composition when an aqueous composition mainly composed of a pigment and an adhesive is applied to liner base paper And / or 15 to 77 parts by weight of delaminated kaolin, and (c) 3 to 20 parts by weight of plastic pigment, and the total of (a) + (b) + (c) is 70 parts by weight or more. A coating liner is disclosed (see Patent Document 5). However, its purpose is to obtain a coating liner suitable for gravure printing and excellent in blank paper gloss and printing gloss, and when a liner having a coating layer of this pigment composition is subjected to aqueous flexographic printing, Only inks with inferior ink density and inferior print finish can be obtained. Furthermore, in order to obtain a coating liner excellent in blank paper gloss and printing gloss without occurrence of flexo printing mottling, as a smoothness characteristic of the coating layer surface, a pressure type smoothness meter was used under a pressure condition of 5 kgf / cm ² . A coating liner having a smoothness of 3.0 μm or less when measured and a ratio of 0.3 to 0.8 with the smoothness measured at 20 kgf / cm ² has been proposed (see Patent Document 6). This proposal shows that the porosity of the coating layer is effective in improving the flexo ink mottling, but the gloss, particularly the printing gloss, is lowered if the smoothness at low pressure is not high. However, the eye-catching effect in the state of a cardboard box is greatly influenced by vivid colors, that is, ink coloring properties, rather than printing gloss. As in this proposal, in order to obtain printing gloss, it is necessary to tighten the conditions of the smoothing process. When the processing conditions are strict, the porosity of the coating layer is impaired, the absorbability of the flexographic ink is inferior, and the color developability of the ink can be obtained at an insufficient level.

  In recent years, it has been forced to reduce industrial waste from activities associated with production from the viewpoint of environmental conservation. Even in the paper industry, the treatment of paper sludge has become a problem. Papermaking sludge is a solid raw material that is mixed with wastewater without being used in fibers such as pulp, which is a papermaking material, organic matter mainly composed of starch and synthetic adhesive, and inorganic matter mainly composed of white pigment, Consists of lignin washed out in the pulping process, fine fibers, or waste paper-derived filler, printing ink adhering thereto, and excess sludge resulting from the biological wastewater treatment process. The main sources of paper sludge other than excess sludge generated in the biological wastewater treatment process are those that flow out through the wire during paper making, those that occur during the removal of contaminants in the waste paper treatment process, the deinking process, and the washing process. The waste water containing these solids is separated and recovered by a solid content separation device using precipitation or flotation, and then required. Correspondingly, after being subjected to biological treatment such as activated sludge treatment, it is discharged. The solid content separated and recovered by such treatment and the excess sludge generated by the final biological treatment of waste water become papermaking sludge.

  In the past, paper sludge generated from paper mills was often landfilled as industrial waste, but recently, organic substances in sludge are burned in incinerators such as fluidized bed furnaces and stoker furnaces. At the same time, the volume of papermaking sludge is reduced. However, since papermaking sludge contains inorganic substances, there is a problem that a large amount of residue (incinerated ash) remains after combustion. At present, some of the incineration ash is mixed with cement, used as an antioxidant for iron making, and a soil conditioner, but most of it is landfilled as industrial waste. In the future, as waste paper is reused, the amount of papermaking sludge becomes extremely large, and waste disposal becomes increasingly difficult. In addition, processing costs that are rising year by year are expected to press the profits of the pulp and paper industry. For this reason, in the paper industry that recycles used paper, the problem of papermaking sludge is extremely serious and its effective use is strongly demanded as part of its countermeasures. For this reason, if paper sludge incineration ash (inorganic matter) can be reused as papermaking fillers and coating pigments as papermaking materials, not only industrial waste will be reduced, but also the utilization rate of wastepaper will be improved. It can be linked and environmental problems can be solved. Many methods for reclaiming and reusing paper sludge for papermaking materials have been studied for such a social environment.

JP 2001-146697 A JP 2002-317395 A JP 2004-232158 A JP 2004-231901 A Japanese Patent Application Laid-Open No. 11-279989 JP 2000-314095 A

The present invention relates to a liner having a sufficient whiteness visually using a regenerated pigment made from paper sludge and having excellent color development and printing uniformity for flexographic inks, particularly aqueous flexographic inks, and the like. The manufacturing method of the corrugated cardboard using this is provided.

The coating liner according to the present invention is a coating liner in which a paint mainly composed of a pigment and an adhesive is applied to one side of a liner base paper made by combining at least two layers. The pigment in the paint contains papermaking sludge. It contains a regenerated pigment obtained by combustion treatment, and the combustion treatment is performed using papermaking sludge as a raw material, and is carried out while being transferred through a cylindrical heat treatment furnace. At least 2 of the primary combustion process which burns and removes the easily combustible organic component in sludge at the temperature of 650 degrees C or less, and the secondary combustion process which burns and removes the hardly combustible organic component in sludge at the sludge temperature of 700-850 degreeC. It is characterized by being performed through a staged combustion process .
The regenerated pigment is supplied from a sludge supply port installed at the end of the cylindrical heat treatment furnace in the cylinder direction, and from a sludge discharge port installed at the end opposite to the sludge supply port in the cylinder axis direction. It is preferable that the regenerated pigment be obtained by performing a combustion treatment by an indirect heating method in an air atmosphere during extraction.
The combustion treatment is performed by forcibly discharging the air in the furnace from the sludge supply port side at one end of the cylindrical heat treatment furnace, and sucking the air into the furnace from the fired product discharge port side at the other end. More preferably.
More preferably, the combustion treatment is performed by dividing the inside of the firing chamber of the cylindrical heat treatment furnace.

Pre Symbol combustion process, it is preferable that the combustion process is performed after the forming raw material of paper sludge in granulated or lump.
A suspension process for mixing the fired product after the combustion treatment with water and stirring to obtain a suspension; a carbonation treatment process for obtaining a carbonated product by bringing carbon dioxide into contact with the suspension; and A coating liner obtained by using a regenerated pigment obtained by further providing a pulverization step of pulverizing the carbonated product is preferable.

The regenerated pigment is preferably a regenerated pigment obtained from a fired product in which the calcium carbonate in the papermaking sludge is decomposed to exceed 50% during the combustion treatment step.
It is more preferable that calcined kaolin is contained as a pigment other than the regenerated pigment among the pigments in the paint.
Corrugated cardboard using the coating liner as described above is preferable.

  According to the present invention, a papermaking sludge, most of which is disposed of as industrial waste, is effectively used, has a sufficient whiteness by visual observation, has excellent ink color development in flexographic printing, and has good printing uniformity. Or it became possible to provide cardboard.

Sludge is waste generated from sewage or industrial wastewater of an industrial plant or process. Since sewage and factory wastewater contain solids, they are discharged after being settled and separated in a clarifier or a coagulation sedimentation tank. At this time, the solid content contained in the wastewater as waste is sludge. This waste consists of organic substances and inorganic substances such as pigments. Papermaking sludge is a mixture of organic substances such as cellulose and starch and inorganic particles such as calcium carbonate, kaolin, and talc contained in dehydrated white water called dehydrated white water in the used paper recycling process, pulp manufacturing process and papermaking process. More specifically, contaminants removed in the waste paper processing process, those generated during the deinking process and washing process, those generated during the washing process in the pulping process, and organic substances that flowed into the white water through the wire during paper making And a mixture of inorganic particles can be used. By collecting sludge from white water in the disaggregation process, which is the first stage of the deinking process in the used paper recycling process, the burden on the deinking process, bleaching process, and washing process in the used paper recycling process is reduced, and the used paper processing cost is reduced. In addition, the load of wastewater treatment can be reduced, which is preferable. In particular, in the used paper recycling process, a large amount of inorganic particles derived from the used paper material flows out into the white water. The white water can be agglomerated to recover inorganic particles efficiently. For example, it can be obtained from a normal waste paper pulp manufacturing process, and if it is a disaggregation treatment, water can be used from either a conventionally known low-concentration pulper or high-concentration pulper. For the deinking treatment of waste paper, any conventionally known method can be used, and squeezing from a washing machine in each step can also be used. In addition, in the case of white water obtained from used paper raw materials with low whiteness, it is preferable to remove ink particles from white water by white water flotation treatment. The inorganic component (ash content) in the papermaking sludge is a main component in which kaolin (clay) and calcium carbonate derived from a papermaking filler or a coated paper pigment account for about 80 to 95% by weight of the whole inorganic component, A small amount of talc, titanium dioxide, etc. are mixed. The ratio of kaolin, which is the main component of the inorganic component, and calcium carbonate varies somewhat depending on the type of waste paper to be treated, but is generally in the range of 20/80 to 80/20 by weight ratio of kaolin / calcium carbonate. . Further, the calcium in the inorganic component (ash) (CaO equivalent), aluminum _(Al 2 _{O 3} basis) and silicon each content ratio (calcium / aluminum / silicon) of the (SiO ₂ equivalent), 13-73 / 12 -40 / 15-47.

  As a method for obtaining a regenerated pigment from papermaking sludge, a method of improving the whiteness by burning unburned carbon by reburning incinerated ash obtained by incineration of papermaking sludge (Patent Document 7), an organic material in the sludge To produce an inorganic material that does not contain organic substances (Patent Document 8), to separate and use sludge incineration ash that is burned using a fluidized bed furnace and that has low unburned carbon (Patent Document 8) Document 9), a method of forming paper sludge, incineration with an internal combustion rotary kiln, etc., and pulverizing (Patent Documents 10 and 11), granulating and forming paper sludge, drying, carbonizing, and organic content in the rotary kiln Can be burned efficiently to obtain incinerated ash and neutralized with carbon dioxide gas at the same time as pulverization (Patent Document 12).

  Further, in order to efficiently burn black carbide in organic matter, paper sludge is first combusted and then coarsely pulverized, and organic matter remaining in secondary combustion is combusted and further pulverized (Patent Document 13), primary Combustion is used as an ignition function, and in secondary combustion, combustion is performed while promoting contact with oxygen (Patent Document 14), a first stage in which organic compounds in paper sludge are incinerated, and residual carbonaceous material under excessive oxygen supply After heat treatment in the second stage of incineration, a method in which the heat treatment product is converted into an aqueous suspension and carbon dioxide is blown (Patent Document 15). After drying papermaking sludge, organic components are completely burned in a combustion furnace, or coarsely crushed or Examples of the method include pulverization during multi-stage combustion and combustion, such as a method in which carbon dioxide gas is blown into an aqueous dispersion after pulverization (Patent Document 16). Further, in order to achieve both suppression of decomposition of calcium carbonate and whiteness, a method of blowing carbon dioxide when burning a carbon component (Patent Document 17) can also be applied.

  In order to reduce the hardness of the recycled inorganic particles from the papermaking sludge, a slurry of ash particles and calcium hydroxide incinerated at a high temperature at which the hydrocarbon material in the sludge is oxidized is produced, and the slurry is carbonated. As a method for producing a composite granular material in which calcium carbonate is precipitated on the surface of ash particles, and other methods, it is possible to prevent the formation of high hardness compounds by mixing and burning incinerated ash with an alkali metal compound. A method of producing an amorphous silica fine particle by acid treatment can be applied. A regenerated pigment obtained by a method for producing a porous granule in which incinerated ash is included in silicic acid by immersing the incinerated ash in an alkaline solution containing silicic acid and neutralizing the incinerated ash with acid. Can be used.

  FIG. 1 shows a basic flow sheet as an example of a more preferable method for obtaining inorganic particles as a regenerated pigment from papermaking sludge. FIG. 1 is a view showing a basic flow sheet of a method for producing inorganic particles to be regenerated pigments preferably used in the present invention. The following description will be made according to the basic flow sheet.

[Sludge]
Sludge is a raw material for inorganic particles according to the present invention. Raw material paper sludge is a combination of processes such as agglomeration, precipitation, concentration, and dewatering as a sludge recovery process for wastewater discharged from various processes in the paper mill such as pulping, paper manufacturing, and used paper recycling. Thus, the solids (various types of papermaking sludge) collected from each wastewater can be used alone or mixed and used as raw material sludge as appropriate. Of these, sludge from the used paper recycling process is subjected to agglomeration and dehydration treatment on the deinking waste liquid separated and discharged from the used paper pulp by pressurized flotation (flotation or flotation) and / or washing in the used paper deinking process. It is recommended to collect the solids in the deinking wastewater as deinking sludge. Also, when recovering sludge from waste paper raw materials with low whiteness, it is better to sufficiently perform deinking treatment and flotation treatment in the waste paper recycling process and remove ink particles including carbon black as much as possible. If necessary, a plurality of sludge pressurization and / or washing steps may be added. In addition, the deinking sludge collected from the wastepaper deinking process is separated into high-quality wastepaper, newspaper wastepaper, magazine (coating paper) wastepaper, etc., and deinking sludge is prepared for each type of wastepaper. The deinked waste paper classified by waste paper type can be used alone or as a mixture and appropriately used as a raw material sludge.

The inorganic component (ash content) in the papermaking sludge is a main component in which kaolin (clay) and calcium carbonate derived from a papermaking filler or a coated paper pigment account for about 80 to 95% by weight of the whole inorganic component, A small amount of talc, titanium dioxide, etc. are mixed. The ratio of kaolin, which is the main component of the inorganic component, and calcium carbonate varies somewhat depending on the type of waste paper to be treated, but is generally in the range of 20/80 to 80/20 by weight ratio of kaolin / calcium carbonate. . Further, the calcium in the inorganic component (ash) (CaO equivalent), aluminum _(Al 2 _{O 3} basis) and silicon each content ratio (calcium / aluminum / silicon) of the (SiO ₂ equivalent), 13-73 / 12 -40 / 15-47.

  The ratio of the organic component and the inorganic component in the papermaking sludge varies somewhat depending on the type of waste paper to be treated and the degree of the deinking process. However, the weight ratio of the inorganic component / organic component is generally 30 / 70-80 / 20. Range.

  Apart from sludge, RPF (Refused Paper & Plastic Fuel) mainly composed of low-grade waste paper that is difficult to reuse as a papermaking material and its associated plastic can also be used as a raw material.

[Dehydration process]
Examples of a method for recovering raw material sludge from wastewater of various processes as a solid content include methods such as filtration, centrifugal separation, pressure dehydration, and pressing, and a papermaking sludge having a required water content is obtained by combining the various methods. Suitable filtration devices, have referred filtering device with rotary screen, and as the dewatering device, there is pressure and squeezing and dewatering equipment called screw press, these filtration apparatus, a squeezing device alone, Or it can be used in appropriate combination

  Since the solid content concentration in the sludge varies depending on the capacity of the dehydrator, it is usually 5 to 60% by mass. However, the solid content concentration exceeding 70% by mass can be achieved by the current dehydrator or concentrator capacity. difficult.

[Drying process]
In the present invention, the solid concentration of sludge used in the heat treatment step is not particularly limited, but from the viewpoint of reducing the energy cost during the heat treatment step and from the viewpoint of reducing the heat treatment apparatus, the sludge solid concentration is Since it is preferable to make it as high as possible, it should be 70% or more. However, although only the above-mentioned dehydration step varies depending on the capacity of the dehydrator, the solid content concentration is about 5 to 60% by mass, and therefore it is recommended to further increase the solid content concentration by drying treatment.

  In order to increase the solid content concentration of the sludge, it is preferable to provide a drying step for drying the sludge before the heat treatment step as shown in FIG. The dryer used in the drying process is not particularly limited, and a direct heating rotary kiln, an indirect heating rotary kiln, an air flow dryer, a fluidized bed dryer, an oscillating fluid dryer, a rotary / aeration rotary dryer (cyclone), or the like is used. be able to. Moreover, as a heat source of these dryers, it is possible to reduce energy cost by using the exhaust heat of the baking process mentioned later.

  The temperature of the drying process may be set to 600 ° C. or less in an apparatus for drying using hot air such as an air dryer or a rotary / aeration rotary dryer in order to prevent combustion and carbonization of sludge. It is preferably 250 ° C. or less. If this hot air temperature is too high, sludge will ignite, and if the firing conditions at that time are not appropriate, there is a concern that the readily combustible organic components will carbonize and become incombustible. Moreover, in order to improve the drying efficiency in the drying process, it is preferable to break up sludge finely, forcibly with a stirrer or mechanical roll, etc., and classify the sludge to about 300 to 2000 μm as necessary. And drying.

  The sludge used in the heat treatment step of the present invention is not particularly limited as long as it has a size and shape that can come into contact with oxygen when the sludge is laminated in the heat treatment apparatus. However, if the sludge is made fine and the size is uniform, the sludge is laminated like a close packing, and oxygen does not enter into the lamination, so the burning of organic matter, especially carbon, may be insufficient and the whiteness may not improve There is sex. If the sludge is too large, the carbon cannot be burned completely, and unburned carbon may remain in the center of the sludge lump. From the above, the sludge used in the present invention preferably has a length or diameter in the range of 2 mm to 30 mm. As the shape, a columnar shape, a spherical shape, an ellipse, a triangle, other polygonal shapes, or those having irregularities can be used.

  In order to form sludge into the desired size and shape as described above, granulation can be performed. The method of granulating sludge is a method using a compression molding machine such as a briquette machine or a roller compactor, a method using a semi-dry granulator such as a disk pelleter, a rolling granulation method, a stirring granulation method, an extrusion molding. There are laws.

  Moreover, even if it does not granulate sludge using a granulation molding machine as mentioned above, it is also possible to adjust the size with a screw feeder or the like when putting hydrous sludge into the dryer or putting dried sludge into the heat treatment device. Is possible. It is also possible to adjust the size and shape with a sludge dryer. In other words, it may be formed into a certain block size.

[Heat treatment process]
Since the heat treatment process of the present invention is performed in an excess air (oxygen) atmosphere to improve combustion efficiency, the heat treatment apparatus can be reduced in size and labor can be saved. The heat treatment temperature is controlled by the method described later so that the ink pigment such as carbon black in the sludge and the organic matter such as fiber and polymer can be stably burned.

  An example of a heat treatment apparatus used for such a heat treatment step is shown in FIG. FIG. 2 is a configuration diagram of a heat treatment apparatus using an indirectly heated rotary kiln used in the heat treatment process of the present invention.

  There are no particular limitations on the firing furnace that is the main part of the heat treatment process. Box furnaces such as tunnel kilns, roller hearth kilns, pusher kilns, shuttle kilns, vertical cylindrical furnaces, rotary horizontal cylindrical furnaces, screw-type horizontal furnaces A cylindrical furnace or the like can be used. As a system for supplying sludge, there are a batch system and a continuous system, but a continuous system capable of treating a large amount is preferable. It is preferable to use a rotary horizontal cylindrical furnace that has good heat transfer to the sludge and allows sludge in the heating furnace to come out to the surface more uniformly, or a screw type horizontal cylindrical furnace that can flow. A rotary kiln, which is a rotary horizontal cylindrical furnace that is as simple as possible from the viewpoint of maintenance of equipment and has a low driving energy, is preferable. As the shape of the rotary kiln firing chamber, a cylindrical shape, a hexagonal shape, or the like can be used. As rotary kilns, external heating continuous rotary kilns from Takasago Industry Co., Ltd., continuous external heating rotary kilns IRK type from Kurimoto Iron Works, indirect heating continuous rotary kiln RKC-SG type from Noritake Engineering Co., Ltd., Iwasa Machinery Industry Co., Ltd. An externally heated rotary kiln manufactured by Co., Ltd. can be used. In addition, by providing a lifter and a stirring member that can be driven to rotate in the kiln furnace, more sludge and oxygen are in uniform contact with each other, so that the organic matter is burned efficiently and the whiteness of the sludge burned product is improved. However, it is more preferable because the quality becomes uniform. In addition, the multi-cylinder kiln and the kiln firing chamber have a multi-partition partition structure, which increases the heat transfer area, reduces sludge stacking / deposition in the kiln furnace, and contacts sludge with oxygen. Since heat transfer to the sludge is improved, the whiteness of the sludge fired product is improved, and uniform quality can be obtained. In addition, by using a multi-partition partition structure in the firing chamber, it is possible to reduce sludge stacking / deposition as described above compared to conventional kilns. Can be scaled. The number of divisions in the firing chamber is not particularly limited, but is preferably 6 divisions or more, and more preferably 10 divisions or more.

  Therefore, since a horizontal or vertical cylinder is used as a heat treatment apparatus using these firing furnaces that can be suitably used for the heat treatment apparatus used in the heat treatment process of the present invention, a cylindrical type using a cylindrical heat treatment furnace This is called a heat treatment apparatus.

  FIG. 2 shows a configuration diagram of an example of a heat treatment apparatus suitably used in the heat treatment process of the present invention. As shown in FIG. 2, a continuous indirect heating type that is an example of a cylindrical heat treatment apparatus, in which sludge S that has been processed individually or in combination with dehydration, drying, and granulation is sent from a drying apparatus that is not shown. The rotary kiln 1 is introduced into a supply hopper 2 serving as a sludge supply port installed at one end of the rotary kiln 1 in the cylinder axis direction, and supplied to the firing chamber 9 in the rotary kiln 1 via a screw feeder 10. As the sludge S passes through the firing chamber 9 of the rotary kiln 1, the organic components in the sludge S are combusted. The sludge S after combustion is taken out of the furnace through the sludge discharge port 8 installed at the end opposite to the sludge supply port in the cylinder axis direction, and sent to the next step.

  An exhaust fan 4 as an exhaust means is installed in the vicinity of the supply hopper 2. This exhaust fan forcibly exhausts the air in the rotary kiln 1, and the air installed in the vicinity of the sludge discharge port 8 into the rotary kiln 1. Air is sucked into the rotary kiln 1 from the supply port 3 as indicated by a dashed arrow A. In this way, the air flow indicated by the broken-line arrow A always occurs from the air supply port 3 toward the exhaust fan 4. This air flow becomes an unburned matter conveying air flow A described later. The air amount is controlled by controlling the exhaust amount of the exhaust fan 4. This amount of air is preferably controlled to be excessively sucked so that the inside of the furnace is in an excess (rich) oxygen atmosphere. Details of this will be described later.

  Heat for heating the inside of the rotary kiln 1 is mainly supplied from the indirect heating means 5. The inside of the baking chamber 9 is indirectly heated by this heat. Heat is also generated by burning combustible components in the sludge in the firing chamber 9 of the rotary kiln 1, but the heat supplied from the indirect heating means 5 is much larger than this heat. By controlling the indirect heating means 5, the temperature in the rotary kiln 1 is kept uniform. The indirect heating means 5 can be electrically heated, but heating with a combustion gas of kerosene or heavy oil or heating with a gas burner is economically preferable. Combustion exhaust gas discharged from existing incineration facilities can be used, and steam or the like can also be used. In the example shown in FIG. 2, the combustion exhaust gas is supplied as the indirect heating means 5 by the circulation blower 7.

  The organic components in the sludge are basically combusted in the firing chamber 9 of the rotary kiln 1, but a part of the unburned matter is put on the air flow A and taken out from the rotary kiln 1. Since the air flow forcedly exhausted through the exhaust fan 4 is hot air, it is preferable to use the hot air circulation fan 6 to be sent to a sludge dryer (not shown) and reused as heat energy.

  As described above, the heat treatment step of the present invention is performed by an indirect heating method capable of uniform temperature control in an excess air (oxygen) atmosphere. The indirect heating method is one method for heating the firing chamber (inside the furnace) 9. In the indirect heating type combustion furnace, the hot air generated by the combustion gas or the combustion gas and sludge are not in direct contact with each other. This is called because a partition is provided. As another heating method, there is a direct heating method in which a flame, combustion gas, or hot air is blown from one end of a cylinder. Since the direct heating type firing furnace is a method of heating from one end of the firing chamber (inside the furnace), the temperature differs greatly between the heating side and the opposite side, and the temperature of the entire firing chamber (inside the furnace) is accurately set. I can't control it. In contrast, the indirect heating method is not a method in which combustion gas or hot air is blown from one end of the cylinder as in the direct heating method, but a method in which the entire firing chamber (inside the furnace) is heated. Uniform temperature control is facilitated. Uniform temperature control is important for the following reasons.

  In the sludge, there are ink components such as carbon black, organic substances such as fibers and polymers, and inorganic particles such as calcium carbonate, kaolin, and talc. In order to improve the whiteness of the sludge fired product, it is necessary to remove carbon black which is a black ink component. In order to completely burn a single carbon black, at least a combustion treatment time of 60 minutes at 600 ° C. and 20 minutes at 850 ° C. is required in an excess air atmosphere. Good. However, if the temperature is too high, the inorganic particles in the sludge undergo a sintering change, the sludge fired product becomes hard, and it tends to exhibit properties that are undesirable as a papermaking material.

  The hardening of the inorganic particles by the high-temperature heat treatment is caused by a thermal alteration phenomenon of inorganic calcium carbonate and kaolin (clay) mainly contained in the following sludge. That is, calcium carbonate begins to be decarboxylated from the vicinity of over 600 ° C., and at least part of it begins to be decomposed into calcium oxide, and completely decomposes into calcium oxide at 900 ° C. Talc does not change its crystal structure up to 900 ° C. Titanium dioxide is stable even at 1000 ° C. and does not change at all. Kaolin is crystal water desorbed from around 400 ° C. and exists as amorphous metakaolin up to 500 to 850 ° C. This amorphous metakaolin is called calcined kaolin, and is an inorganic particle that is bulky, has good opacity, and is excellent in smoothness. When the temperature exceeds 900 ° C., γ-alumina and mullite are generated. Since these γ-alumina and mullite are very hard, wire wear and coating blade wear are deteriorated, which is not preferable as a papermaking material. In addition, if there is calcium oxide decomposed from amorphous metakaolin and the above-mentioned calcium carbonate in a region slightly exceeding 850 ° C., hard and unsuitable galenite is generated by a chemical reaction.

  Therefore, it is preferable that the sludge temperature of the heat treatment step of the present invention does not exceed 850 ° C. at which a hard fired product is not generated. Further, when the maximum temperature is less than 600 ° C., it takes a very long processing time to improve the whiteness, which not only increases the energy cost but also increases the heat treatment apparatus, which is not preferable in practice. Accordingly, a preferable sludge temperature is preferably 600 ° C. or higher and 850 ° C. or lower, and more preferably 600 ° C. or higher and 800 ° C. or lower.

  Moreover, in the heat treatment process of the present invention, the sludge temperature may be raised stepwise to a temperature not exceeding 850 ° C.

  Eventually, if it is going to prevent the sludge fired product from becoming hard in this way, the sludge temperature at the time of firing will be set lower, and it is difficult to completely burn the organic content in the sludge S, There is a risk that some unburned matter typified by carbon black remains. In addition, the temperature shown here is a sludge temperature when baking is performed in the baking chamber 9, and is strictly different from the atmospheric temperature in the heat treatment apparatus. Although the atmospheric temperature in the heat treatment apparatus depends on the temperature of the supplied air, it is usually lower than the sludge temperature.

  In the heat treatment step of the present invention, the reason why the heat treatment apparatus is heat-treated in an excess air atmosphere, that is, in an oxygen-rich atmosphere is to efficiently burn organic substances contained in the sludge. The excess (rich) oxygen atmosphere here refers to supplying sufficient air (oxygen) necessary for combustion to the organic matter to be burned so that the residual oxygen concentration in the combustion exhaust gas is 5% or more. In this state, organic matter can be completely burned. It is also possible to adjust the sludge temperature according to the amount of air to be exhausted and the temperature of the air to be sucked.

  The amount of air sucked into the heat treatment apparatus is preferably equal to or greater than the theoretical oxygen amount necessary for burning organic components. However, since the combustion gas generated by burning the organic component is larger than the air amount corresponding to the theoretical oxygen amount, it is necessary to exhaust at least the generated combustion gas to make excess (rich) oxygenation. . Therefore, the amount of air to be sucked is controlled by adjusting the exhaust amount of the exhaust fan. The displacement is preferably 1.1 times the theoretical air amount, more preferably 1.5 times or more, and even more preferably 2 times or more. However, if the amount of intake air is too large, the sludge temperature is lowered, which is not preferable in terms of energy cost. Further, the inhaled air may contain more carbon dioxide than usual. Note that when the oxygen amount in the heat treatment apparatus is less than the theoretical oxygen amount and becomes deficient, it becomes in an oxygen-poor state and the sludge is carbonized, so that unburned carbon remains in the sludge. In order to remove this unburned carbon, it is necessary to increase the heat treatment temperature or to treat for a long time. After all, it is difficult to obtain a desired sludge fired product. Therefore, it is absolutely necessary to avoid making the inside of the furnace poorly oxygenated.

  In the present invention, the whiteness of the sludge fired product is increased by high-temperature treatment in order to burn the sludge S more completely in an excess (rich) oxygen atmosphere, but as described above, a hard fired product is generated. It becomes easy to do.

  In the present invention, as shown in FIG. 2, the air supply port 3 is installed in the vicinity of the sludge discharge port 8, and the exhaust fan 4 that discharges the air flow A for conveying unburned matter is installed in the vicinity of the sludge supply port 2. In this case, the unburnt substance conveying air stream A can be generated in a direction opposite to the direction B in which the sludge S travels in the heat treatment apparatus.

  The method of generating the unburned matter conveying air flow A in the direction opposite to the direction B in which the sludge S travels is called a countercurrent method in the present invention. In this counterflow method, the unburned matter conveying air flow flows in the opposite direction to that sent to the sludge discharge port 8 side of the sludge fired product, so that the unburned product can be efficiently removed from the sludge fired product. The whiteness of the fired product can be improved, which is more preferable. In particular, the unburned matter generated during the combustion in the first stage of the heat treatment process is difficult to be completely burnt until later, and can be effectively removed by this counter-flowing unburned matter carrying air flow.

  Therefore, in order to achieve higher whiteness, 100% complete combustion of unburned sludge is guaranteed, and 100% combustion is abandoned rather than setting the sludge temperature higher. A feature of the present invention is to obtain inorganic particles that have high whiteness and do not contain a high-hardness composite by overlooking the generation of unburned matter and, rather, removing the unburned matter from the sludge fired product. The above-mentioned unburned substances are unburned organic substances, and most are unburned carbon particles, in other words, carbide particles. That is, it is a carbon black-like substance, and the carbon black is in the form of a fine powder having a size of 10 to 500 nm and a specific gravity of 1.8 to 1.9. In order to remove the unburned matter in the form of fine powder, the air in the furnace is exhausted by the exhaust fan 4 to generate an unburned matter transfer air flow A in the heat treatment apparatus and put it on the transfer air flow A. The unburned material is taken out. In this way, it is very preferable to forcibly exhaust the unburned-substance conveying air flow using an exhaust fan or the like. More preferably, air is forcibly introduced in addition to such forced exhaust.

  The flow rate of the unburned product air flow by forced exhaust or the like is not particularly limited as long as it can remove the fine powdery unburned product, but when the flow rate is slow, the air flow flows to the supply hopper 2 side. Therefore, there is a concern that unburned matter cannot be removed well and is mixed in the sludge fired product, resulting in a decrease in whiteness. The flow rate of the unburned matter transporting air flow for transporting unburned matter containing carbon black having the above properties is preferably 0.4 m / min or more, more preferably 0.8 to 1.5 m / min or more, and particularly Preferably it is 1.5 m / min or more. However, if the flow rate of the air flow is too high, there is a greater possibility that the fired sludge will be mixed with the exhaust fan 4 side and the thermal efficiency will be reduced. The flow rate of the air flow was theoretically determined from the values of the exhaust fan, the air temperature, and the like, and the temperature in the heat treatment apparatus.

  On the other hand, an example of an air inflow method opposite to the other method counter-current method is shown in FIG. FIG. 3 is a configuration diagram of another example of a heat treatment apparatus using an indirectly heated rotary kiln used in the heat treatment process of the present invention. 3, the members denoted by the same reference numerals as those in FIG. 2 are the same as those described in FIG. In the heat treatment apparatus of FIG. 3, the exhaust fan 4 is installed in the vicinity of the sludge discharge port 8. Therefore, the unburnt substance conveying air flow A ′ and the sludge traveling direction B ′ are in the same direction. Such a method is called a parallel flow method in the present invention. In this co-current method, since the discharge port for separating and extracting the sludge fired product and the unburned product is in the same direction, there is a concern that the unburned product is likely to be mixed into the sludge fired product. Further, in the parallel flow method, as described above, even if the flow rate of the air flow for conveying unburned material is adjusted, the unburned material is likely to be mixed into the sludge fired product, so the counter current method is more preferable.

  Further, in the present invention, when the sludge combustion temperature in the heat treatment apparatus becomes high, by increasing the air inflow amount above a certain level, excess sludge combustion heat is discharged out of the heat treatment apparatus by the air flow. That is, the combustion temperature of the sludge S in the firing chamber 9 can be lowered by discharging the high-temperature combustion exhaust gas in the firing chamber 9 of the rotary kiln 1 to the outside of the rotary kiln 1 by the exhaust fan 4 on the sludge supply side. Therefore, in the present heat treatment apparatus, contrary to the above, even if the temperature is high, the sludge combustion heat is discharged out of the heat treatment apparatus by increasing the air inflow amount above a certain amount, that is, the main body cylinder part of the rotary kiln. The temperature can be lowered by discharging the heat together with the air flow from the sludge supply side to the outside. That is, it is possible to perform control so as to avoid a rise above the set heat treatment temperature. Therefore, the unburned matter transport air flow A described above also serves as a sludge combustion heat exhaust air flow. Also in this point, the counterflow method has an exhaust port near the sludge supply port that discharges the airflow, so that the sludge combustion heat is heat treated without passing through the heat treatment device compared to the parallel flow method. It is more preferable because it can be discharged out of the apparatus and the sludge temperature can be easily controlled.

In addition, when the sludge combustion temperature is high, the combustion can be suppressed and the temperature can be controlled by reducing the air inflow amount, but in the present invention, in the heat treatment apparatus, for the purpose of firing the sludge with a high degree of whiteness. Since it is necessary to make the oxygen rich state and the sludge burn sufficiently, it is not preferable to reduce the air inflow amount more than necessary.
On the other hand, even when the sludge combustion temperature is low, a large amount of air can be introduced to increase the temperature. That is, in the present invention, the combustion temperature can be adjusted by the air inflow amount.

  In addition, the difference in the characteristics of each of the counterflow type and the parallel flow type air inflow methods is prominent in a rotary horizontal cylindrical furnace and a screw type horizontal cylindrical furnace. On the other hand, in a vertical cylindrical furnace, it is difficult to make a difference because it is necessary to flow air in order to improve the contact between air and sludge, but the parallel flow method is slightly more effective than the countercurrent method. is there.

  Unburned matter that is separated and taken out on the air flow A for unburned matter conveyance is removed by a bag filter provided after the hot air circulation fan 6 and / or captured by a combustion device (both not shown) together with exhaust gas. It is more preferable to remove or burn.

  The hot air discharged from the heat treatment apparatus is preferably reused as a heat source such as a heat treatment apparatus or a drier by the heat circulation fan 6, so that the energy cost can be reduced.

  The time during which the sludge is heated to a constant temperature (heat treatment time) is not particularly limited, but there is a time during which the organic matter remaining in the firing chamber 9 is completely burned without being blown off by the air flow A for conveying the unburned air flow. Since it is necessary to hold, one hour or more is preferable. However, an unnecessarily long heat treatment time not only increases the energy cost but also increases the heat treatment apparatus. Therefore, the heat treatment time in the heat treatment step of the present invention is more preferably 1 to 5 hours. By suitably controlling the conditions such as the heat treatment time, sludge temperature, air flow rate, flow rate, etc., the decomposition rate of the calcium carbonate component in the sludge is preferably 50% or more, more preferably 60% or more, and even more preferably 70%. That's it.

[Firing product suspension process]
In the present invention, as illustrated in FIG. 1, the calcined product after the heat treatment step may be provided with a suspension step after the heat treatment step of mixing and stirring the calcined product with water to obtain a calcined product suspension. . The purpose of the suspension process is to dissolve calcium contained in the sludge calcined product as calcium ions in water, and there is no particular restriction on the suspension temperature of the calcined product, but it is necessary to maintain the temperature when the treatment temperature is high Since it is economically unfavorable, it is usually preferable to carry out at 20 to 80 ° C.

  The solid content concentration of the baked product suspension can be adjusted to the range of 5 to 20% by mass to efficiently carry out the subsequent carbonation treatment, and the viscosity of the suspension is kept low so that the fluid agitation and liquid feeding can be maintained. In order to maintain good properties. When the solid content concentration of the fired product suspension is less than 5% by mass, the productivity is inferior because it is not preferable, and when it is higher than 20% by mass, the viscosity of the fired product suspension becomes high. This is not preferable because the stirring power increases and the operability is inferior.

In addition to the calcined sludge of the present invention, calcium oxide (CaO: quick lime) or calcium hydroxide [Ca (OH) ₂ : slaked lime] is separately added to the calcined product suspension as necessary. In this case, calcium oxide and calcium hydroxide can be mixed with calcium hydroxide [Ca (OH), which is a form after dehydration. ₂ : Slaked lime] can be added up to 100 parts by weight (sludge: calcium hydroxide = 50: 50) with respect to 100 parts by weight of the burned sludge. Although calcium hydroxide can be added in excess of 100 parts by weight, it is not preferable because the blending ratio of the sludge fired product in the slaked suspension is reduced and sludge utilization does not proceed.

[Carbonation process]
In the sludge containing calcium carbonate, calcium carbonate (CaCO ₃ ) is decomposed in a heat treatment step of 600 ° C. or higher. If the calcined ash containing decomposed calcium carbonate is made into an aqueous suspension, it becomes highly alkaline, and there are problems such as an increase in slurry viscosity and poor dispersion. Therefore, it is used as it is as a paper filler and coating pigment. Is difficult. When the sludge combustion efficiency is improved as in the heat treatment step of the present invention, the decomposition of calcium carbonate is promoted. That is, the whiteness of the baked ash after the heat treatment step of the present invention and the decomposition rate of calcium carbonate are in a proportional relationship, and in order to obtain a desired white baked ash, the calcium carbonate in the sludge is decomposed to exceed 50%. ing. In order to obtain high white baked ash, 60% or more is decomposed, and in order to obtain high whiteness baked ash, 70% or more is decomposed. For this reason, it is preferable to neutralize the alkali component by some method such as carbonation treatment or aluminum sulfate mixing treatment on the heat-treated sludge calcined ash.

In the present invention, by performing the carbonation step after the baked product suspension step, calcium ions in the baked product suspension are regenerated and converted to calcium carbonate (CaCO ₃ ), thereby lowering the pH of the regenerated inorganic particle slurry. Can do. In addition, by making the pH of the regenerated inorganic particle slurry 11 or less, preferably 10 or less, it is possible to suppress an increase in slurry viscosity and to prevent poor pigment dispersion. The regenerated inorganic particles mainly include calcium carbonate particles newly precipitated by carbonation treatment and amorphous component particles in which kaolin is modified by heat treatment. This amorphous component shows properties similar to those of calcined kaolin. Therefore, this amorphous component can be called a calcined kaolin-like component.

  In addition, when calcium carbonate is not contained in the sludge, calcium carbonate is not decomposed and calcium ions are not liberated, so that the calcined ash can be dispersed at a high concentration, and the calcined product suspension step after the heat treatment step and Even if a carbonation step is not used, it can be reused as it is as a papermaking material.

  A carbonation process can be performed by the method similar to a normal light calcium carbonate manufacturing process. That is, carbon dioxide gas or carbon dioxide-containing gas is blown into the fired product suspension. The gas used for carbonation is industrially preferably a carbon dioxide-containing gas, and the concentration of carbon dioxide in this case is not particularly limited, but is preferably 5 to 40% by volume, more preferably 10 to 35% by volume. The carbon dioxide containing gas is used. The carbon dioxide-containing gas includes, for example, sludge calcined exhaust gas, limestone calcined exhaust gas, lime calcined exhaust gas, waste incineration exhaust gas, power generation boiler exhaust gas, exhaust gas discharged from a causticized calcium carbonate calcined kiln used in a pulp manufacturing process, etc. May be used after dust removal by an appropriate means.

  The carbon dioxide gas or the carbon dioxide-containing gas is blown into the fired product suspension so as to have a rate of 0.5 to 15 L / min per 1 kg of the fired product as carbon dioxide gas. If the amount of carbon dioxide introduced is less than 0.5 L / min, the productivity is inferior, and an amount exceeding 15 L / min can be adopted, but it is commensurate with the power load necessary to increase the amount of use. The effect cannot be expected. The reaction start temperature for carbonation is preferably 30 to 80 ° C, more preferably 40 to 70 ° C. The shape of the regenerated calcium carbonate component contained in the regenerated inorganic particles can be rice granule, spindle shape, colloidal shape, needle shape, cubic shape, plate shape, etc. There is no particular limitation on the shape, and carbonation In order to obtain crystals having a desired shape during the process, seed crystals may be added.

  In addition, the inorganic particles after the carbonation treatment of the present invention have a particle size suitable for a filler for papermaking, in which fine calcium carbonate primary particles generated by the carbonation treatment aggregate to form secondary particles (aggregated particles). It may become. In such a case, this suspension can be used as it is by blending it with a papermaking raw material such as pulp as a papermaking filler.

[Dehydration and dispersion process]
When the regenerated inorganic particle slurry (slurry after carbonation) of the present invention is used as a coating pigment, a dehydration step of dehydrating the composition regenerated inorganic particle slurry after the carbonation step into a dehydrated composition; It is preferable to include a dispersion step of adding water to the dehydrated composition obtained by the dehydration step to form a slurry-like dispersion composition. The dehydration step can be performed by operations such as filtration, centrifugation, pressure dehydration, and pressing. As a suitable dehydrating apparatus, there is a press filtration apparatus called a filter press, and a dehydrated cake of a carbonized product can be obtained. The dispersion process may be any process as long as water is added to the dehydrated composition obtained by the dehydration process to form a slurry-like dispersion composition. It is preferable to add a dispersing agent in addition to moisture during the dispersing step, because it is possible to satisfactorily disperse the regenerated inorganic particles using sludge as a raw material, improving the quality as a papermaking material and facilitating handling. As the dispersing agent, for example, a general dispersing agent used in the manufacture of a papermaking material such as a synthetic polymer dispersing agent such as sodium polyacrylate can be used.

[Crushing process]
In the present invention, the pulverization step may be provided after the dispersion step. By carrying out the pulverization treatment, the particle diameter of the regenerated inorganic particles can be reduced, and the smoothness is improved, which is preferable. As a pulverizer used in the pulverization step, a wet pulverizer such as a sand mill, a wet ball mill, a vibration mill, a stirring tank mill, a flow tube mill, or a coball mill can be used. Moreover, you may grind | pulverize, blowing in a carbon dioxide.

  The size (particle diameter) of the regenerated inorganic particles of the present invention is preferably 0.1 to 20 μm as an average particle diameter by laser diffraction particle size distribution measurement, and is 0 when used as a coating pigment. .3 to 5 .mu.m, particularly preferably 3 to 15 .mu.m when used as a paper filler for internal addition.

  This average particle size can be used as a paper filler and coating pigment so that it can provide excellent wire yield during paper making and excellent opacity, whiteness, smoothness, and printability when finished into paper products. In addition, a particle size that is balanced in terms of operation and quality is selected. Therefore, by setting the average particle size of the regenerated inorganic particles within the range of the particle size, in operation, it can be handled in the same manner as conventional papermaking fillers and coating pigments, and the regenerated inorganic particles are internally added. As for the quality of the base paper and the coated paper coated with the recycled inorganic particles, the same quality as that of the conventional paper filler and coating pigment can be expressed.

  Incidentally, when the average particle size of the recycled inorganic particles becomes finer than 0.1 μm, it is effective for improving the opacity, whiteness, smoothness, etc., but on the other hand, it is used as a filler for papermaking. In order to develop sufficient coating layer strength when used as a pigment for coating, in addition to the difficulty that the operability becomes unstable due to the poor wire yield. In addition, there is a disadvantage that a remarkably large amount of adhesive is required, which is not preferable. On the other hand, if the average particle size of the recycled inorganic particles is larger than 20 μm, the wire yield of the filler is improved when used as a papermaking filler, but on the other hand, the wire wearability is deteriorated and the wire is damaged. Besides being difficult to receive, when used as a coating pigment, the smoothness and gloss of the coated paper product are lowered, resulting in a decrease in printability.

  It is preferable to provide a dispersion step and a pulverization step after the dehydration step so that the regenerated inorganic particles have the desired particle size described above, but the average particle size of the regenerated inorganic particles after the dispersion treatment falls within the range of the particle size described above. In this case, the dispersion of inorganic particles after the dispersion treatment may naturally be used as it is as a papermaking filler and a coating pigment without performing the pulverization step.

  Further, in the dispersion step, the dehydrated composition of the regenerated inorganic particles is mixed with the calcium carbonate slurry to obtain a mixed slurry, which is pulverized using a wet pulverizer, so that the quality is better than calcium carbonate and moreover than the calcium carbonate slurry. Also, the pulverization time can be shortened, and a highly concentrated slurry can be prepared. The ratio between the regenerated inorganic particles and calcium carbonate can be adjusted according to the blank paper quality of the coated paper and is not particularly limited.

  As for the process in this method, the heat treatment process is essential, but the drying process, granulation process, suspension process, carbonation process, dehydration / dispersion process, and pulverization process can be appropriately selected and combined. Devices that perform these processes are combined to form one plant.

Inorganic particles obtained as in the following can be used more preferably as a playback pigment.
As a more preferable heat treatment method for obtaining inorganic particles from papermaking sludge, it is preferable to use a heat treatment having at least two stages of combustion steps including a primary combustion step and a secondary combustion step. The heat treatment process will be described in detail below.

[Heat treatment process]
In the present invention, all organic components contained in the papermaking sludge are surely burned and removed by the above-described at least two-stage combustion treatment. That is, the combustion treatment in the present invention is performed while transporting the raw papermaking sludge in the cylindrical heat treatment furnace, and the primary combustion process is performed under the excess air atmosphere under the sludge temperature of 650 ° C. or less in the secondary combustion process. Are set to combustion conditions with a sludge temperature of 700 to 850 ° C. in an excess air atmosphere. The excess air atmosphere means an air atmosphere that does not cause incomplete combustion by giving a sufficient amount of oxygen to the combustion of organic components.

First, in the primary combustion process, the combustion conditions are relatively low in an excess air atmosphere, so the easily combustible organic components in paper sludge are easily pyrolyzed and ignited starting from the functional group in the molecule, and carbonized. It disappears without burning. In the next secondary combustion step, high-temperature combustion conditions are obtained in an excess air atmosphere, so that the non-combustible organic components remaining without being burned in the primary combustion step are also surely burned and lost. In such a two-stage combustion process, it is reasonable to burn and remove easily combustible organic components without changing them into hard-to-burn carbides, and the entire organic components in paper sludge can be burned and removed efficiently in a short time. can Ru.

  When the sludge temperature in the primary combustion process exceeds 650 ° C., as described above, the easily combustible organic component is carbonized and changed to a hardly combustible organic component, and the combustion efficiency is deteriorated. Further, if the combustion temperature in the primary combustion process is too low, even a readily combustible organic component is difficult to pyrolyze and ignite, and the combustion efficiency deteriorates. Therefore, the lower limit of the sludge temperature is preferably 250 ° C. Furthermore, the most suitable baking conditions of a primary combustion process are the range used as the sludge temperature of 350-630 degreeC.

  On the other hand, if the sludge temperature in the secondary combustion process is less than 700 ° C., it takes time to burn the non-combustible organic component, and the combustion efficiency deteriorates. On the other hand, when the sludge temperature becomes high temperature combustion exceeding 850 ° C., suitability as a papermaking material is impaired due to generation of a hard sintered material generally called gehlenite. In other words, when used as a paper filler or coating pigment prepared from a fired product mixed with such a hard sintered product, the manufacturing facilities such as paper making wire and coating blade are damaged. Will worsen the product quality. Thus, the most suitable firing conditions for the secondary combustion process are the ranges where the sludge temperature is 750 to 800 ° C.

  In addition to performing the combustion process in the two stages consisting of the primary and secondary combustion processes described above, the combustion process as a transition section from the primary combustion process to the secondary combustion process is sandwiched, or the primary and secondary combustion processes. One or both of these can be further divided into a plurality of combustion steps having different combustion temperatures (sludge temperatures), so that there are three or more stages.

  The combustion treatment time of the primary combustion process is preferably at least 10 minutes and within 5 hours, particularly preferably within 15 hours and within 2 hours, and if it is too short, the flammable organic components in the papermaking sludge There is a risk that the removal of combustion will be insufficient, and if it is too long, heat energy will be wasted. In any case, it is important to allow sufficient time for all flammable organic components to burn off. The combustion treatment time in the secondary combustion process is preferably at least 10 minutes or longer and within 5 hours, particularly preferably 20 minutes or longer and within 2 hours, and if it is too short, it is difficult to burn in the papermaking sludge. There is a risk that the burning and removal of the organic component will be insufficient, and if it is too long, the heat energy will be wasted. And it is preferable to make the ratio of the combustion processing time of a primary combustion process and a secondary combustion process into the range of 1/10-10/1 in a primary combustion process / secondary combustion process.

  The cylindrical heat treatment furnace used for the combustion treatment includes a rotary kiln furnace called a rotary kiln and a screw kiln furnace depending on the transfer method of the object to be processed, but a rotary kiln furnace is preferable in terms of combustion efficiency. . The at least two-stage combustion treatment can be performed in a single cylindrical heat treatment furnace, or by using a plurality of cylindrical heat treatment furnaces that are different for each stage. It is more advantageous in terms of equipment efficiency and equipment cost.

  It should be noted that the temperature rising region generated between the primary combustion process and the secondary combustion process when the combustion treatment is performed using the one cylindrical heat treatment furnace, specifically, the combustion temperature is increased from 650 ° C. to 700 ° C. About the area | region to perform, it is preferable to make it as short as possible, and it is especially preferable to set it as less than 10 minutes. Thus, shortening the temperature rising region between the primary combustion process and the secondary combustion process leads to compactness by shortening the overall length of the cylindrical heat treatment furnace, which is advantageous in terms of equipment efficiency and equipment cost.

  As the heating method of the cylindrical heat treatment furnace, the indirect heating method (external heat method) is preferable to the direct heating method (internal heat method). That is, in the direct heating method, since a large amount of air (oxygen) is consumed to burn the heat source gas in the processing furnace, there is a concern that the combustion of the organic components contained in the papermaking sludge becomes incomplete due to air shortage. Furthermore, the control of the furnace temperature (sludge temperature) becomes very difficult due to the combustion of the heat source gas. On the other hand, the indirect heating method does not consume furnace air for the heat source, so that the inside of the furnace can be reliably set to an excess air atmosphere and the degree of heating from the outside can be freely changed. Control of the furnace temperature becomes extremely easy.

  As a heating means in the above indirect heating method, heating by an electric heater or induction current is possible, but from the viewpoint of energy cost, burning of kerosene, heavy oil, etc. is carried out in a heating jacket surrounding the cylindrical furnace body. A method of introducing gas, combustion exhaust gas discharged from an existing incinerator, high-temperature air, superheated steam, or the like, or spraying combustion gas from a gas burner on the peripheral wall of the processing furnace and heating is recommended. Further, high-temperature exhaust gas that has undergone combustion treatment in the furnace body and combustion exhaust gas from the pretreatment drying step can also be used as part of the heating medium or heat source of the heating means.

  In order to produce a high-quality fired product, it is recommended that the supply of combustion air into the furnace body of the cylindrical heat treatment furnace be performed from the fired product outlet side. In other words, the air supply from the fired product outlet side causes the air flow direction in the furnace body to be opposite to the transfer direction of the object to be treated (paper sludge and its fired product). Even if the non-combustible organic component of combustion is scattered in the furnace, which is in the state of soot, the floating substance such as soot is carried back to the raw material supply port side and burns on the air flow, or Further, since the exhaust gas is discharged outside the cylindrical heat treatment furnace, it is possible to prevent the black unburned, non-combustible organic component from being mixed into the fired product, thereby obtaining a fired product with high whiteness. Thus, unburned, non-combustible organic components discharged to the outside of the cylindrical heat treatment furnace accompanying the exhaust are collected and removed with a bag filter or the like, or are combusted with appropriate heating means together with the exhaust. It should be lost.

  As described above, in order to supply combustion air into the furnace main body from the fired product discharge port side, air may be blown from the fired product discharge port side, but air is sucked by exhaust on the raw material supply port side. Is preferred. That is, because the furnace is negatively exhausted by forcibly exhausting from the raw material supply port side, if an air supply port is provided in the vicinity of the fired product discharge port, air is automatically discharged from the air supply port by the negative pressure. Inhaled into the furnace. Thus, in such air supply by exhaust on the raw material supply port side, the air supply amount can be easily controlled by the exhaust amount, and air can be reliably distributed over the entire length of the long furnace body by a stable air flow. .

  The above air supply amount is an amount that gives an oxygen amount 1.1 to 5 times the theoretical oxygen amount required for complete combustion of the organic components contained in the papermaking sludge in the furnace body in an excess air atmosphere. The amount is preferably set, more preferably an amount giving an oxygen amount of 1.5 to 5 times, and particularly preferably an amount giving an oxygen amount 2 to 5 times. If the air supply amount is too small, it becomes difficult to make the furnace body have an excess air atmosphere, and the whiteness of the fired product may be lowered by the carbide remaining due to incomplete combustion of the organic components. On the other hand, if the air supply amount is too large, the inside of the furnace will be excessively cooled by the supply air, so it is necessary to increase the degree of heating by the heating means in order to maintain the combustion temperature, and the energy cost will increase accordingly. Become. Therefore, since this combustion air only needs to contain oxygen that sufficiently burns organic components, there is no problem even if the content of carbon dioxide is larger than that of normal outside air.

  If a suitable combustion treatment state of the papermaking sludge according to the method of the present invention appears, in the primary combustion process, a large amount of easily combustible organic components, which occupy most of the organic components in the sludge, will burn in the presence of sufficient oxygen. It burns up, and this combustion is in a state that continues from 1/2 to 2/3 of the primary combustion process. Similarly, in the secondary combustion process, the remaining flame-retardant organic components are burned, but since the content is small, the flame is not raised, but the high temperature of 700 to 850 ° C keeps the sludge burning up. It will be in a state of burning.

  FIG. 4 is a longitudinal side view schematically showing an indirect heating type rotary kiln furnace (rotary kiln) K1 which is one configuration example of a cylindrical heat treatment furnace used in the present invention. As shown in the figure, the rotary kiln furnace K1 has an outer periphery of a horizontal cylindrical rotary drum 9 that is a furnace body surrounded by a heating jacket 20, and on the raw material supply port 9a side of one end of the rotary drum 9, A raw material input port 2 is provided at a distance from the exhaust port 30, and a raw material supply means 10 such as a screw feeder is disposed between the raw material input port 2 and the raw material supply port 9 a of the rotary drum 9. An air supply port 3 and a fired product outlet 8 are provided facing the fired product discharge port 9 b at the other end of the rotary drum 9.

  In the heating jacket 20, hot air sent through the hot air blowers 71 is released by a plurality of valves by a plurality of indirect heating means 5 A and 5 B for primary combustion and secondary combustion, respectively. From the outlet 72, it is introduced separately into a front heating space 20a on the raw material supply port 9a side and a rear heating space 20b on the fired product discharge port 9b side. Further, the exhaust port 30 is provided with an exhaust means 4 such as an exhaust fan, and the air in the rotary drum 9 is exhausted by the operation as shown by the broken line arrow A, and the decompression action accompanying the exhaust is performed. External air is sucked into the rotary drum 9 from the air supply port 3. Reference numeral 6 denotes an exhaust circulation blower provided on the downstream side of the exhaust port 30.

  Although the rotary cylinder 9 is not illustrated strictly, the rotary cylinder 9 is inclined to a very gentle downward slope from the raw material supply port 9a side to the fired product discharge port 9b side. As a result of the rotation, the internal workpiece is gradually moved from the raw material supply port 9a side to the fired product discharge port 9b side by gravity.

  In order to perform the baking process of the papermaking sludge S with the rotary kiln furnace K1 having the above-described configuration, as shown by the solid line arrow B, the papermaking sludge S of the raw material charged into the raw material charging port 2 is rotated by the raw material supply means 10 by the rotating drum In the process of feeding into the raw material supply port 9a and transferring to the fired product discharge port 9b side by the rotation of the rotary drum 9, the organic components in the sludge S are removed by indirect heating with hot air introduced into the heating jacket 20. Combustion is performed in two stages, the primary combustion process and the secondary combustion process described above.

  That is, the two-stage combustion process is performed while maintaining the entire inside of the rotary drum 9 in an excess air atmosphere by the intake of air from the air supply port 3 accompanying the exhaust from the exhaust port 30 due to the operation of the exhaust means 4. The heating degree is adjusted by the temperature and the introduction speed of hot air introduced from the indirect heating means 5A, 5B of the system to the front heating space 20a and the rear heating space 20b in the heating jacket 20, respectively, and is represented by a virtual line c in the figure. As can be seen, the sludge temperature of 650 ° C. or lower (preferably 250 ° C. or higher, most preferably 350 to 630 ° C.) is defined as the primary combustion zone Z1 in the front region in the rotary drum 9 corresponding to the front heating space 20a. ), And the rear region in the rotary drum 9 corresponding to the rear heating space 20b is controlled to a sludge temperature of 700 to 850 ° C. (preferably 750 to 800 ° C.) as the secondary combustion zone Z2.

  As a result, the paper-making sludge S is combusted and removed without carbonizing the easily combustible organic components contained in the process of passing through the primary combustion zone Z1, and then contained in the process of passing through the secondary combustion zone Z2. The components are burned and removed, and are discharged from the fired product discharge port 9b of the rotary drum 9 as a high-whiteness fired product containing no unburned organic components and hard sintered products, and are discharged from the furnace through the fired product outlet 8 To be taken out.

  In addition, what is necessary is just to set the processing time (passing time) in both combustion area Z1, Z2 with the rotational speed and inclination degree of the rotary drum 9. FIG. Further, the length ratio of both combustion sections Z1 and Z2 in the rotary drum 9 is preferably in the range of 1/10 to 10/1 in the primary combustion process / secondary combustion process as described above. It can be arbitrarily adjusted according to the relative ratio of the size of the region where hot air is introduced into the heating jacket 20 from the indirect heating means 5A, 5B. Therefore, various measuring means such as a thermocouple and an infrared temperature sensor can be used for temperature measurement for controlling the combustion temperature (sludge temperature) in both combustion sections Z1 and Z2. A thermocouple is preferable in terms of cost.

  The furnace body of the cylindrical heat treatment furnace used in the present invention is not limited to a horizontal cylindrical type such as the rotary drum 9 in the rotary kiln 1 of the above-described configuration example, and a plurality of interiors are provided by providing partitions and partition walls inside. It is also possible to employ a rotating cylinder having a multi-divided structure divided into compartments or a multi-cylinder (tube bundle) multi-chamber structure. Examples of the rotary cylinder having the multi-divided structure or the multi-body (tube bundle) multi-chamber structure are shown in FIGS. 5 to 7 are cross-sectional views (diameter cross-sectional views) in a direction orthogonal to the longitudinal direction of the horizontally long rotating drum, and the vertical direction of the drawing coincides with the actual vertical direction. Yes.

  The rotating drum 9 shown in FIG. 5A has a six-partitioned partition structure having a substantially hexagonal outer shell 12a. The partition 12b has a hexagonal section in the inside, and is divided into six compartments 13 having a regular triangular section. It is divided. FIG. 5 (b) shows the state of lamination and accumulation of the papermaking sludge S in each compartment 13 when the rotating cylinder 9 to which the granulated material of the papermaking sludge S is rotated in the direction of arrow C. Yes.

  The rotating drum 9 shown in FIG. 6 (a) has a six-cylinder multi-cylinder (tube bundles) structure in which six pipe parts 14 are bundled in a substantially annular shape by a donut plate-like pipe part fixing member 15. The central hollow portion 16 surrounded by the six pipe portions 14 communicates in the axial direction through the center hole 15a of the pipe portion fixing member 15. FIG. 6 (b) shows the state of lamination and deposition of the papermaking sludge S in each pipe section 14 when the rotating cylinder 9 supplied with the granulated material of the papermaking sludge S is rotating in the direction of arrow C. Yes.

  7A has a 12-partitioned partition structure, and the annular space between the inner cylinder part 17a and the outer cylinder part 17b forming a double pipe is radially divided by 12 partition walls 17c. Thus, twelve compartments 18 are formed, and the inside of the inner cylindrical portion 17a forms a hollow portion 16. FIG. 7 (b) shows the state of lamination and deposition of the papermaking sludge S in each compartment 18 when the rotating cylinder 9 to which the granulated material of the papermaking sludge S is rotating is rotated in the direction of arrow C. Yes.

  As illustrated in FIGS. 5 to 7, if the horizontally long rotating drum 9 has a multi-divided structure or a multi-cylinder (tubing bundle) multi-chamber structure, the supplied papermaking sludge S has a plurality of compartments or cylinders. Therefore, the object to be processed (paper sludge S) in the transfer process in the rotary cylinder 9 is compared with a simple horizontal cylindrical rotary cylinder that forms a single furnace space. , Calcined product) is significantly reduced in thickness, and the stirring action of the object to be processed accompanying the rotation of the rotary drum 9 is strengthened, so that the contact between the air (oxygen) for burning the organic components and the object to be processed is achieved. The efficiency is remarkably improved, and the combustion efficiency of the organic component is dramatically increased, so that a high-quality fired product and inorganic particles can be obtained.

  In addition, it is recommended that the number of divisions of the transfer path in such a multi-divided structure or a tube bundle (multi-body) multi-chamber structure is at least 6 or more in order to sufficiently exhibit the above-described effects. . Further, the divided structure of the rotary drum is not limited to the structure illustrated in FIGS. 5 to 7, and is a multi-partition partition structure in which the cross section is divided into triangular compartments such as an 18-divided type, a 24-divided type, and a 36-divided type. In addition, various structures are possible, such as a rotating body structure having a multi-body / multi-division structure in which a partition or partition is provided for each tubular member of a multi-body structure and the total number of divisions is 6 to 126. Further, in addition to the rotary drum and the structure in which the inside of the tubular member is partitioned into a plurality of compartments by a partition wall, a driven stirring blade having a shape similar to the partition wall is not provided in the rotary drum and the tubular member. By inserting in a fixed state, the inside of the rotating drum may be divided into a plurality of compartments, and the papermaking sludge S supplied into the rotating drum may be distributed to the plurality of compartments.

  As shown in FIGS. 6 and 7, when a rotary cylinder 9 having a multi-divided structure or a multi-cylinder (tubular bundle) structure provided with a hollow portion 16 along the axial direction is employed, it is indirectly from the outside. If indirect heating is performed from the inside (center side) using the cavity 16 in addition to heating, the combustion temperature can be controlled more accurately and higher heat treatment efficiency can be achieved. As the indirect heating means from the inside, various heating media and heat sources similar to the indirect heating means from the outside described above can be adopted.

JP-A-11-310732 Japanese National Patent Publication No. 10-505055 JP 2001-11337 A JP 2002-167523 A Japanese Patent No. 3611830 JP 2004-176208 A JP 2001-262002 A JP-A-2005-53984 JP-A-10-29818 JP 2002-356629 A JP 2004-262701 A

  The larger the blended amount of the regenerated pigment obtained by the method described in any of the above documents, the more effectively industrial waste is used, so that the cost of waste treatment is reduced, which is desirable from the viewpoint of economy. Therefore, the blending amount of the regenerated pigment is preferably 1 to 100 parts with respect to the total pigment. If the amount is less than 1 part, the amount of waste processing is not reduced and the processing cost is increased, which is not preferable in terms of economy.

In the present invention, the coating layer containing the regenerated pigment may be a single layer or a multilayer, but the total coating amount is preferably ² to ²⁰ g / m ² . When the coating amount is within this range, it is possible to obtain a liner which is excellent in economic efficiency and excellent in water-based flexo ink color development. A more preferable coating amount is 3 to 10 g / m ² . In addition, as the composition of the regenerated pigment, as described in the paragraph [0014], the main component of the inorganic component in the paper sludge is kaolin / calcium carbonate in the range of 20/80 to 80/20. The ratio of the kaolin component and the calcium carbonate component heat-denatured in the regenerated inorganic material after the step of bringing carbon dioxide into contact with the inorganic material is in the range of about 20/80 to 80/20. When the amount of the kaolin component thermally modified by the baking treatment, that is, the calcined kaolin-like component is 10% by mass or more, the flexographic ink color developability is more preferable. If it is less than 10% by mass, it is easy to add expensive calcined kaolin, which is economically disadvantageous.

  As pigments other than regenerated pigments, which are paint pigments applied to the liner base paper surface layer, pigments commonly used in the papermaking field, such as calcined kaolin, clay, structured kaolin, engineered kaolin, aluminum hydroxide, titanium dioxide 1 or 2 types of light calcium carbonate, heavy calcium carbonate, barium sulfate, zinc oxide, satin white, calcium sulfate, talc, plastic pigment, etc. can be used, but calcined kaolin absorbs flexo ink It is the most desirable pigment because of its excellent properties and high ink color development. However, in order to keep the liner surface after coating sufficiently white and to obtain ink color development and printing uniformity in flexographic printing, the amount of calcined kaolin similar to the amount of calcined kaolin in the regenerated pigment is added. It is preferable to adjust the total amount to be in the range of 50 to 99.7 parts in the total pigment. Furthermore, it is desirable to use talc. The reason for this is that when foreign material comes into contact with the liner surface during rubbing and rubs, if the liner surface has a high frictional resistance, the liner surface may become soiled with foreign matter, but talc is coated with a flat pigment. This is because it has the property of reducing the frictional resistance of the layer and reduces contamination by foreign matter. In addition, clay, structured kaolin, engineered kaolin, and plastic pigment are inferior in the absorbability of flexographic ink, so it is desirable to use them within a range that does not impair the desired effect of the present invention, but organic pigments such as plastic pigments. Is not preferred because of its poor flexo ink absorbability.

  Furthermore, it is preferable to add a water retention agent to the coating material to be coated on the liner base paper surface because the coating suitability is improved. As the water retention agent to be added, sodium salt of carboxymethyl cellulose, which is generally called CMC in the papermaking field, hydroxyethyl cellulose, polyvalent carboxylic acid acrylic copolymer called synthetic water retention agent, methacrylic acid and acrylic ester And the like. Among them, sodium salt of carboxymethyl cellulose is easily coated uniformly, and those having a degree of etherification of 0.60 to 1.00 and a degree of polymerization of 600 to 1200 are particularly preferable in terms of good handleability.

  The adhesive in the paint of the present invention is not particularly limited, and a known adhesive used in the general coated paper manufacturing field is appropriately used. For example, styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, conjugated diene copolymer latex such as styrene-methyl methacrylate-butadiene copolymer latex, acrylic ester and / or methacrylate ester Acrylic polymer latex such as a polymer or copolymer latex, vinyl polymer latex such as ethylene-vinyl acetate polymer latex, or these various polymer latexes were modified with a functional group-containing monomer such as a carboxyl group. Examples include water-dispersible adhesives such as polymer or copolymer latex, synthetic resin adhesives such as polyvinyl alcohol and olefin-maleic anhydride resins, and starches such as oxidized starch, positive starch, esterified starch, and dextrin. The One or more of these water-dispersible and / or water-soluble adhesives can be appropriately selected and used. In general, the blending ratio of the pigment and the adhesive is 5 to 60 parts by weight of the adhesive with respect to 100 parts by weight of the pigment.

  Additives such as surface sizing agents, anti-slip agents, and dyes may be used in combination in the coating material used in the present invention within a range that does not impair the effects of improving ink color development and finishing printing uniformity.

When coating the paint of the present invention on the liner base paper, a coating device generally used for coated paper production can be used, for example, blade coater, air knife coater, roll coater, reverse roll coater, bar coater, curtain. On-machine or off-machine liners using coating equipment such as coaters, die slot coaters, gravure coaters, chaplex coaters, 2 roll size press coaters, gate roll size press coaters, film metallizing size press coaters, etc. The base paper is coated with a single layer or multiple layers. The solid content concentration of the pigment composition at the time of coating can be selected in the range of 10 to 75% by weight, but the coater is applied so that the coating amount remains within the preferable range of ² to 20 g / m ^2. It is preferable to adjust appropriately considering the above.

  In order to further improve the coating surface and printability, the coating liner coated in the present invention is a calender device such as a super calender using a cotton roll as an elastic roll and a soft nip using a synthetic resin roll as an elastic roll. The smoothing process can be performed. The soft nip calender can set the heat-resistant temperature on the surface of the synthetic resin roll higher than that of the cotton roll, so it can be processed at high temperatures, and compared with the super calender when the same smoothness is targeted. This is a preferred embodiment because the treatment linear pressure can be set low.

The liner base paper used in the present invention is not particularly limited as a constituent pulp. For example, unbleached, bleached chemical pulp, mechanical pulp, non-wood pulp, magazine waste paper, leaflet waste paper, newspaper, which is wood pulp, is used. Used waste paper, office waste paper, information paper waste paper, corrugated waste paper, waste paper pulp such as paperboard waste paper, pulp of manila hemp, etc., or a mixture of two or more kinds as appropriate. Considering the strength and the like, it is preferable to use kraft pulp and used corrugated paper.
In the present invention, from the viewpoint of resource protection, strength balance, and cost, it is a preferred embodiment that 70% by weight or more of corrugated used paper is blended in the surface layer.

Internally added chemicals can also be used as necessary, for example, sizing agents such as sulfuric acid bands and rosins, paper strength enhancers such as polyamide and starch, drainage yield improvers, water resistance agents such as polyamide polyamine epichlorohydrin, Dyes are used. The illustrated pulp and internal chemicals are used, and a base paper having a multilayer structure formed by combining two or more pulp layers is used.
In the production of liner base paper, it is more preferable to perform a smoothing treatment with the above-described calender device after forming a multilayer structure, because a uniform coated surface is formed at the time of coating in the next step.
The flexographic ink for printing on the coating liner of the present invention is not particularly limited, and examples thereof include an alcohol type, a cosolvent type, an aqueous type, and a UV curable type. Among these flexographic inks, an aqueous type is also included. However, it is also excellent in safety, workability, and economical efficiency, and is an embodiment in which the effects of the present invention are most prominent.

  In addition, the flexographic printing press used is classified into three types, a stack type, a line type, and a central impression type, depending on how the printing units are arranged, but any type can be used.

  The coated liner obtained by the present invention can be used as a cardboard liner provided on at least one outermost surface, and the cardboard of the present invention is provided. Corrugated cardboard includes single-sided cardboard with a liner bonded to only one side of the core, double-sided cardboard with liners bonded to both sides of the core, and multiple-level cardboard with multiple layers of core / liner laminates However, the present invention is applicable to any cardboard.

There is no restriction | limiting in particular as a core of the corrugated member which comprises a cardboard with a liner, The thing currently used for the general cardboard can be used. As raw material pulp, semi-chemical pulp (SCP), chemi-grind pulp (CGP), corrugated waste paper pulp, magazine waste paper pulp, unbleached kraft pulp, kraft pulp, synthetic fiber, etc. can be used. It is preferable to use a lot of waste paper pulp such as corrugated waste paper pulp and magazine waste paper pulp. The core may be a laminated paper, and may further be a laminated paper having a synthetic resin adhesive layer between layers.

The corrugated board of the present invention can be produced by applying a conventionally known corrugated board production method as it is, for example, through a corrugator treatment in which a core and a liner are bonded through an adhesive substance. Adhesive substances include starch paste and synthetic resins (polyethylene, polypropylene, polyamide, polyester, ethylene / unsaturated carboxylic acid copolymer, styrene / butadiene copolymer, butadiene / acrylonitrile copolymer, styrene / butadiene / acrylonitrile copolymer). Polymer, polyvinyl acetate, ethylene / vinyl acetate copolymer, polyacrylate copolymer, styrene / acrylate copolymer, etc.).

  Specifically, (1) A method in which an adhesive layer is formed on the surface of the core or liner by extrusion lamination or application of a synthetic resin emulsion, etc., and then these are stacked, pressed and heated to be bonded, (2) A method in which a synthetic resin film is interposed between the core / liner and the pressure is applied to heat the film, and (3) an adhesive such as a synthetic resin emulsion or solution is interposed between the core / liner. And a method of applying pressure and heating to bond them. In the method (2), a pre-molded synthetic resin film can be fed out and supplied between the core and the liner, or the synthetic resin film can be supplied between the core and the liner while being melt-extruded. You can also

  A single-sided cardboard is manufactured by performing the corrugator process once, and a double-sided cardboard or a multi-stage cardboard is manufactured by repeatedly performing the process multiple times. Double-sided cardboard, for example, is a single facer (SF) in which a core and a liner are bonded with a heat and pressure roll to form a single-sided cardboard, and a liner is further stacked on the core side of the single-sided cardboard obtained by SF. It can manufacture using the corrugator which has the double facer (DF) which runs on a hot plate | board and presses it while pressing. The heating and pressing conditions are not particularly limited. For example, the heating temperature of SF is 150 to 200 ° C., the linear pressure is 20 to 40 kN / m, the pressing time is 0.01 to 0.20 seconds, and the heating temperature of DF is 150 to 200 ° C. A linear pressure of 0.1 to 1.0 kN / m, a pressurization time of 2 to 7 seconds, and the like are preferable.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these ranges. In the examples, “parts” and “%” indicate parts by mass and mass% unless otherwise specified.

About the obtained coating liner, it evaluated by the following evaluation method and the obtained result was shown to Table 1,2. Table 1 shows the evaluation results before and after the indication coating, and Table 2 shows the flexographic printing evaluation results.
The measurement and evaluation of the printing liner in the present invention were performed in an environment of 23 ° C. and 50% RH unless otherwise specified.

Reference example 1
[Sludge]
In the waste paper deinking process mainly used for magazine waste paper at a paper mill with waste paper processing equipment, waste water from waste paper pulp was supplied to a flotation machine and subjected to flotation treatment to obtain white water. A flocculant was added to the obtained white water to agglomerate the solid content in the waste liquid, and then sequentially passed through a rotary screen and a screw press to recover papermaking sludge (deinking sludge) having a solid content of about 50%. . The ash content in the paper sludge was 60%, and the composition was calcium carbonate 55%, kaolin 40%, and talc 5%.

[Heat treatment process]
This heat treatment step was performed by a heat treatment apparatus (countercurrent system) having the configuration shown in FIG. Specifically, a continuous external heating type rotary kiln 1 (IRK-02 manufactured by Kurimoto Iron Works, heated portion: Φ25 × 180 cm) was used as a heat treatment apparatus. Paper sludge S was supplied to rotary kiln 1 from supply hopper 2 which is a sludge supply port at a speed of 3.5 kg / h. The supplied papermaking sludge S is conveyed by a screw feeder 10 to a firing chamber (rotary cylinder) 9 in the rotary kiln 1 and is heat-treated, that is, fired while passing through the firing chamber (rotary cylinder) 9. As the indirect heating means 5, combustion gas from a combustion boiler (not shown) is supplied from the circulation blower 7 and used. At this time, the sludge temperature becomes 850 ° C. by controlling the air flow rate and indirect heating while exhausting the gas in the kiln from the exhaust fan 4 as an unburned matter conveying air flow A at 150 L / min (20 ° C. conversion). And heated for 140 minutes to prepare a fired product.

  The obtained sludge fired product was measured by X-ray diffraction to determine the decomposition rate of calcium carbonate. As a result, the calcium carbonate component was decomposed 100%. Further, the kaolin component was transformed into a 100% amorphous component, and talc was not decomposed at all.

[Firing product suspension process]
The obtained sludge fired product is mixed with 60 ° C. warm water in a suspension tank (dissolving tank) and stirred for 60 minutes while maintaining the suspension tank at 60 ° C. to prepare a 12% fired product suspension. did.

[Carbonation process]
In a carbonation reaction tank, 10 kg of a 12% calcined product suspension at a temperature of 60 ° C. was introduced, and 25% by volume of carbon dioxide-containing gas was blown at 20 L / min while maintaining the reaction tank at 60 ° C., and stirring was performed for 60 minutes. Regenerated inorganic particles were obtained. When the obtained regenerated inorganic particles were measured by X-ray diffraction, the calcium carbonate decomposed by the firing treatment was regenerated to calcium carbonate.

[Dehydration and dispersion process]
The composition after completion of the carbonation step was dehydrated with a filter press to obtain a dehydrated composition having a solid content of about 50%, and then the dehydrated composition was dispersed in water with a coreless mixer so that the solid content was 48%. At the time of dispersion, a polyacrylic acid-based dispersant (trade name: Aron T-50, manufactured by Toa Gosei Co., Ltd.) is added to water in an amount of 1.0 part relative to the solid content of the composition (the dehydrated composition). And a slurry was prepared.

[Crushing process]
The slurry composition after the dispersion step was pulverized using a sand grinder as a wet pulverizer to obtain regenerated inorganic particles having an average particle diameter of 1.6 μm as a regenerated pigment.

[Manufacture of coating liners]
Corrugated cardboard was used for the surface layer, front layer, front layer, middle layer, back layer, and back layer, and the layers were combined into five layers. A dye was added to the surface layer to obtain a liner base paper having a basis weight of 170 g / m ² . The obtained surface layer had L ^* , a ^* , b ^* and whiteness of 66.8, 2.0, 17.0 and 15.0%, respectively.
70 parts of the regenerated pigment obtained in the above process, 30 parts of calcined kaolin (trade name: Ancilex, manufactured by BASF), 0.5 part of water retention agent (trade name: A7055, manufactured by Toagosei Co., Ltd.) (all solid content) The coating liquid consisting of (conversion) was prepared so as to have a concentration of 30%. The prepared paint is coated on the above-mentioned 170 g / m ² liner base paper with a bar coater so that the dry weight becomes 6.0 g / m ² (solid content), dried, and then subjected to a 1 Nip calendar process to be coated liner. Got.

Reference example 2
Besides having different [heat treatment step] described below in Reference Example 1 to obtain a reproduced inorganic particles in the same manner as in Reference Example 1 as a reproduction pigment. A coated liner was obtained in the same manner as in Reference Example 1 from the obtained regenerated pigment.

[Heat treatment process]
This heat treatment step was performed by a heat treatment apparatus (countercurrent system) having the configuration shown in FIG. Specifically, a continuous external heating type rotary kiln 1 (IRK-02 manufactured by Kurimoto Iron Works, heated portion: Φ25 × 180 cm) was used as a heat treatment apparatus. Paper sludge S was supplied to rotary kiln 1 from supply hopper 2 which is a sludge supply port at a speed of 3.5 kg / h. The supplied papermaking sludge S is conveyed by a screw feeder 10 to a firing chamber (rotary cylinder) 9 in the rotary kiln 1 and is heat-treated, that is, fired while passing through the firing chamber (rotary cylinder) 9. As the indirect heating means 5, combustion gas from a combustion boiler (not shown) is supplied from the circulation blower 7 and used. At this time, the sludge temperature becomes 850 ° C. by controlling the air flow rate and indirect heating while exhausting the gas in the kiln from the exhaust fan 4 as an unburned matter conveying air flow A at 150 L / min (20 ° C. conversion). And heated for 140 minutes to prepare a fired product.

The obtained sludge fired product was measured by X-ray diffraction to determine the decomposition rate of calcium carbonate. As a result, the calcium carbonate component was decomposed 100%. Further, the kaolin component was transformed into a 100% amorphous component, and talc was not decomposed at all.
After the pulverization step, regenerated inorganic particles having an average particle size of 1.6 μm were obtained.

Example 1
Regenerated inorganic particles were obtained as regenerated pigments in the same manner as in Reference Example 1 except for the following points. A coated liner was obtained in the same manner as in Reference Example 1 from the obtained regenerated pigment.
[Sludge and pretreatment]
In the waste paper deinking process mainly used for magazine waste paper at a paper mill with waste paper processing equipment, waste water from waste paper pulp was supplied to a flotation machine and subjected to flotation treatment to obtain white water. A flocculant is added to the resulting white water to agglomerate the solid content in the waste liquid, and then sequentially passed through a rotary screen and screw press to make a papermaking sludge (deinking sludge) with a solid content of about 50% as a reference example. Recovered as in 1 . Next, it was dried to a solid content of about 75% using a drier, then granulated and formed into pellets having a diameter of about 12 mm and a length of about 15 mm using a disk pelleter, and the pretreatment was completed.

  The papermaking sludge granulated material after the pre-treatment is used twice as shown in FIG. 2 by using an indirect heating type rotary kiln furnace (inner diameter of the rotating drum 300 mm, length 2400 mm) as shown in FIG. The two-stage baking process of the primary baking and the secondary baking described in detail below was performed. As the rotary drum 9 of the rotary kiln furnace for performing the two-stage firing process, a rotary drum using a multi-partitioned partition wall structure section having six compartments as shown in FIG.

[Primary firing treatment]
The raw paper sludge granulated product S after the pretreatment was supplied to the rotary kiln 1 from the supply hopper 2 which is a sludge supply port at a supply speed of 7.0 kg / h. The supplied papermaking sludge S is transported to a firing chamber (rotary cylinder) 9 in the rotary kiln 1 by a screw feeder as a raw material supply means 10 and is heat-treated, that is, fired while passing through the firing chamber (rotary cylinder) 9. . As the indirect heating means 5, combustion gas from a combustion boiler (not shown) is supplied from the circulation blower 7 and used. At this time, the sludge temperature becomes 630 ° C. by controlling the air flow rate and indirect heating while exhausting the gas in the kiln from the exhaust fan 4 as an unburned matter conveying air flow A at 300 L / min (20 ° C. conversion). And heated for 30 minutes to prepare a primary fired product.

[Secondary firing process]
Next, the primary fired product obtained by the primary firing was subjected to secondary firing. In the secondary baking, the primary baking processed product of the papermaking sludge S was supplied to the rotary kiln 1 from the supply hopper 2 which is a sludge supply port at a supply speed of 7.0 kg / h. The supplied primary firing product of the papermaking sludge S is conveyed to a firing chamber (rotary cylinder) 9 in the rotary kiln 1 by a screw feeder which is a raw material supply means 10, and is heat-treated while passing through the firing chamber (rotary cylinder) 9. That is, it is fired. As the indirect heating means 5, combustion gas from a combustion boiler (not shown) is supplied from the circulation blower 7 and used. At this time, the sludge temperature becomes 850 ° C. by controlling the air flow rate and indirect heating while exhausting the gas in the kiln from the exhaust fan 4 as an unburned matter conveying air flow A at 300 L / min (20 ° C. conversion). And heated for 2 minutes to prepare a secondary baked product.

  The obtained sludge fired product (secondary fired product) was measured by X-ray diffraction to determine the decomposition rate of calcium carbonate. As a result, the calcium carbonate component was decomposed 100%. Further, the kaolin component was transformed into a 100% amorphous component, and talc was not decomposed at all.

For the obtained sludge fired product (secondary fired product), the fired product suspension step, the carbonation step, the dehydration / dispersion step, and the pulverization step were performed in the same manner as in Reference Example 1 , and the average particle size was 1. Regenerated inorganic particles of 5 μm were obtained.
Example 2
A coated liner was obtained in the same manner as in Example 1 except that 40 parts of the regenerated pigment and 60 parts of calcined kaolin (trade name: Ansilex 93, supra) were used.

Example 3
In Example 1 , 3 parts of regenerated pigment, 60 parts of calcined kaolin (trade name: Ancilex 93, supra), 30 parts of talc (NK-KCL, manufactured by Kanematsu Chemical Co.), titanium oxide (KA-100 COSMO CHEMICAL) (Manufactured) A coated liner was obtained in the same manner as in Example 1 except that the amount was 7 parts.

Example 4
In Example 1 , a coated liner was obtained in the same manner as in Reference Example 1 , except that the regenerated pigment was 100 parts and the dry weight was 10 g / m ² .

Comparative Example 1
In Reference Example 1 , a coating liner was obtained in the same manner as in Reference Example 1 , except that 70 parts of kaolin (trade name: manufactured by HG-90 Huber) was used instead of blending the regenerated pigment.

[Measurement of X-ray diffraction]
The sample was crushed in a mortar until coarse particles disappeared, and measurement was performed at a measurement condition of 40 KV, 20 mA, and a measurement range: 5 to 50 degrees using MO3XHF manufactured by Mac Science Co., Ltd.
[Calcium carbonate decomposition rate after combustion treatment]
About each Example, the calcium carbonate decomposition | disassembly rate after heat processing calculates | requires the quantity of the calcium carbonate component in the paper sludge before heat processing by the procedure of i)-vi), and the residual calcium carbonate component in sludge baking products, etc. below. evaluated.

i) Preparation of calibration curve for calcite calcium carbonate Zinc oxide (reagent special grade made by Kishida Chemical Co., Ltd.) as an internal standard substance with respect to calcium carbonate having a crystal structure of calcite (Tama Pearl 222H made by Okutama Kogyo Co., Ltd.) : 5, 1: 1, 5: 1. Next, after each mixture was sufficiently ground using a mortar, it was measured using an X-ray diffractometer (MO3XHF manufactured by Max Science) under the conditions of 40 KV, 20 mA, and a diffraction angle measurement range of 5 to 50 degrees. Based on the X-ray diffraction 100% peak areas of calcium calcite and zinc oxide, a calibration curve of calcium calcite was prepared.

ii) Preparation of calibration curve of aragonite calcium carbonate Calibration of aragonite calcium carbonate was carried out in the same manner as the calibration curve of calcite calcium carbonate except that calcium carbonate having a crystal structure of aragonite (Tama Pearl 123 manufactured by Okutama Kogyo Co., Ltd.) was used. Created a line.

iii) Quantification of calcium carbonate in paper sludge before combustion treatment Weighed zinc oxide (reagent grade above) was added and mixed to the weighed absolute dry paper sludge. Next, the mixture was sufficiently ground using a mortar, then measured using an X-ray diffractometer (MO3XHF, supra) at 40 KV, 20 mA, a diffraction angle measurement range of 5 to 50 degrees, and oxidized. X-ray diffraction 100% peak areas of calcium calcite carbonate and aragonite calcium carbonate with respect to zinc were determined, and the amount of calcium carbonate (g) contained in 1 g of papermaking sludge was calculated based on the calibration curve of each calcium carbonate described above. .

iv) Measurement of ash content of paper sludge Weighed dry dry paper sludge in a muffle furnace at 350 ° C for 30 minutes, weighed the obtained sludge, and contains sludge ash content according to the following formula. The amount (%) was measured.
Ash content (%) = (weight of sludge burned product / weight of paper drying sludge) × 100

v) Quantitative determination of calcium carbonate in the calcined sludge The weighed sludge calcined product was added and mixed with a weighed zinc oxide (reagent special grade mentioned above). Next, the mixture was sufficiently ground using a mortar, then measured using an X-ray diffractometer (MO3XHF, supra) at 40 KV, 20 mA, a diffraction angle measurement range of 5 to 50 degrees, and oxidized. Obtain 100% peak area of X-ray diffraction of calcium calcite carbonate and aragonite calcium carbonate with respect to zinc, and calculate the amount of calcium carbonate (g) contained in 1 g of the sludge fired product based on the calibration curve of each calcium carbonate described above. did.

vi) Decomposition rate of calcium carbonate after combustion treatment The amount of calcium carbonate (g) in 1 g of the sludge fired product is A, the amount of calcium carbonate (g) in 1 g of papermaking sludge is B, and the ash content (%) is C. The decomposition rate of calcium carbonate after the combustion treatment was calculated by the following equation.
Calcium carbonate decomposition rate (%) = 100− [A × (C / 100)] ÷ B × 100

(Whiteness)
The whiteness was determined according to JIS P 8148 (2001) using a spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd.).

(L ^* , a ^* , b ^* , C ^{* of} coating liner)
L ^* , a ^* , b ^* and C ^* were measured according to JIS Z 8722 (2000) using a spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd.) and displayed according to JIS Z 8729 (1994).
Saturation C ^* = ((a ^* ) ² + (b ^* ) ² ) ^1/2

(Visual whiteness index)
When the whiteness measured with a spectral white colorimeter is in the range of 40 to 60%, the hue may deviate from the perception of whiteness visually. From experience, the human eye recognizes white with a brightness of 70 or more and a saturation of 3 or less. Therefore, in the present invention, when the visual whiteness satisfies a brightness of 70 or more and a saturation of 0 to 3, the visual whiteness is It was considered to be inferior, and in all cases where brightness was less than 70 and saturation 3 was exceeded.

(Smoothness)
It calculated | required according to JISP 8151 (2004). Using a pressure-type smoothness meter (measuring device: Parker Print Surf, manufactured by Messmer Buchel), the smoothness was measured when the pressure condition was 0.5 MPa (5 kgf / cm ² ) using soft backing.

(Color development and uniformity of ink in flexographic printing)
K printing proofer (manufactured by RK Print-Coat Instruments), an anilox plate engraved at 100 lines / inch, was obtained using aqueous flexo indigo ink (trade name: AQUACONTE GN39SA indigo, manufactured by Toyo Ink Co., Ltd.) Printed on the coating liner. The cyan ink density of the printed surface was measured with a color reflection densitometer X-RITE 404G (manufactured by X-Rite).
The following visual evaluation was performed for flexographic printing uniformity.
A: The uniformity of the flexographic printing surface is excellent.
○: Slight unevenness is observed on the flexographic printing surface.
X: Light and shade unevenness is remarkably seen on the flexographic printing surface.

(Halftone dot reproducibility)
The ink was printed using a water-based flexographic ink (trade name: FK-99D-260 Kuro PR-7, manufactured by Sakata Inx Corporation) using a Ministry of Finance gravure printing machine. The 50% gradation part was enlarged 25 times, and the following dot evaluation was performed on the state of halftone dots.
○: The shape of the halftone dots is clearly recognized, but there are some defects.
Δ: A halftone dot shape is recognized, but there are more than half of the defects.
X: The shape of a halftone dot is not recognized.

The resulting coated liner is bonded with a corrugator using a core (product name: S120, manufactured by Oji Paperboard Co., Ltd.) and a back liner (product name: SF210, manufactured by Oji Paperboard Co., Ltd.), and a corrugated sheet in the form of an A flute. It was created. Although the hot plate was taken off at the time of bonding, the corrugated cardboard sheets using the coating liners obtained in Examples and Comparative Examples were not much different.
The above evaluation results are summarized in the table below.

As can be seen from the table, the coated liner of the present invention has sufficient whiteness because it uses recycled inorganic particles made from paper sludge as a recycled pigment, has excellent ink color development in flexographic printing, and has printing uniformity. It became good. This is because the regenerated inorganic particles mainly include calcium carbonate particles newly precipitated by carbonation treatment and amorphous component particles in which kaolin is modified by heat treatment. In particular, since this amorphous component shows properties similar to those of calcined kaolin, it is considered that the ink coloring property is excellent and the printing uniformity is good.

The figure which shows the basic flow sheet of the manufacturing method of the inorganic particle which uses as a raw material the sludge used as the reproduction | regeneration pigment used suitably by this invention. The block diagram of an example of the heat processing apparatus using the indirect heating type rotary kiln used for the heat processing process of this invention. The block diagram of another example of the heat processing apparatus using the indirect heating type rotary kiln used for the heat processing process of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a longitudinal sectional side view schematically showing an indirect heating type kiln furnace which is one configuration example used in an embodiment of the present invention. The radial direction sectional view which shows the rotary drum of the 6 division partition structure used for the rotation kiln furnace. Radial direction sectional drawing which shows the rotary trunk | drum of 6 cylinder type multi-cylinder structure used for the same rotary kiln furnace. Radial direction sectional drawing which shows the rotary cylinder of the 12 division partition structure used for the rotation kiln furnace.

Explanation of symbols

1 Indirect heating type rotary kiln 2 Supply hopper (sludge supply port)
4 Exhaust fan 8 Sludge outlet

Claims (9)

In a method for producing a coating liner in which a paint mainly composed of a pigment and an adhesive is applied to one side of a liner base paper made by combining at least two layers, the pigment in the paint is obtained by burning papermaking sludge. It contains regenerated pigment, and the combustion treatment uses papermaking sludge as a raw material, and the combustion treatment is carried out while being transferred through a cylindrical heat treatment furnace. The combustion treatment is performed at a sludge temperature of 650 ° C. or less in an excess air atmosphere. At least two stages of combustion processes are performed: a primary combustion process for burning and removing flammable organic components therein, and a secondary combustion process for burning and removing flammable organic components in sludge at a sludge temperature of 700 to 850 ° C. method for producing a coating liner, characterized in that it is carried out by. The regenerated pigment is supplied from a sludge supply port installed at the end of the cylindrical heat treatment furnace in the cylinder direction, and from a sludge discharge port installed at the end opposite to the sludge supply port in the cylinder axis direction. The method for producing a coated liner according to claim 1, wherein the pigment is a regenerated pigment obtained by a combustion treatment by an indirect heating method in an air atmosphere during extraction. The combustion treatment is performed by forcibly discharging the air in the furnace from the sludge supply port side at one end of the cylindrical heat treatment furnace, and sucking the air into the furnace from the fired product discharge port side at the other end. The manufacturing method of the coating liner of Claim 1 or 2 which is what is. The manufacturing method of the coating liner as described in any one of Claim 1 to 3 with which the said combustion process is performed by what the inside of the cylindrical heat processing furnace was divided | segmented. The method for producing a coating liner according to any one of claims 1 to 4 , wherein the combustion treatment is performed after the raw paper sludge is granulated or formed into a lump shape. A suspension process for mixing the fired product after the combustion treatment with water and stirring to obtain a suspension; a carbonation treatment process for obtaining a carbonated product by bringing carbon dioxide into contact with the suspension; and The manufacturing method of the coating liner as described in any one of Claim 1 to 5 obtained using the regenerated pigment obtained by further providing the grinding | pulverization process which grind | pulverizes a carbonized material. The reproduction pigment, in the combustion process, of claims 1 to calcium carbonate in the papermaking sludge is reproduced pigment obtained from baked product is decomposed by more than 50 percent according to any one of the 6 Manufacturing method of coating liner. As the pigment other than the reproduction pigments of the pigment in the paint, coating method for producing a liner according to any one of claims 1 to 7 including a calcined kaolin. The method of manufacturing a corrugated board, method of manufacturing corrugated cardboard, characterized in that using the coating liner according to any one of claims 1-8.

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