JP5508739B2 - Kraft paper for bag making - Google Patents

Description

  The present invention relates to bag-making kraft paper. More specifically, the present invention relates to a kraft paper for bag making that has processing suitability as a packaging paper for bag making, can be reduced in weight, and is bulky.

  In recent years, recycling and reduction of packaging paper have been promoted from the viewpoint of environmental protection and a recycling society. The plastic bags derived from petroleum raw materials used in supermarkets are on a trend of reduction, and the shift to paper materials is also progressing. In addition, handbags such as shopping bags are also being reduced in weight, such as by reducing the standard size of rice tsubo. It is desired that even if one standard US tsubo goes down, it has processability and strength that can be used for bag making.

  Unbleached kraft paper is used for light packaging applications such as heavy goods bags, square bottom bags, and handbags. In both cases, strong paper strength is required, so unbleached kraft paper for heavy bags is made only from softwood unbleached kraft pulp, and unbleached kraft paper for light packaging uses mainly softwood unbleached kraft pulp. Some are made from unbleached kraft pulp, some using hardwood unbleached kraft pulp.

  On the other hand, as environment-friendly unbleached packaging paper, one containing waste paper pulp is widely known. However, the weight can be reduced, the use of raw materials can be suppressed, and there are not many examples of bulky packaging paper for bag making, and there is still no one that can satisfy the processing suitability for bag making.

  Due to the widespread use of wrapping paper, for example, (1) it is bulky (can be reduced in weight), (2) has high printability, and (3) bagmaking suitability. It is required to be excellent. Among these, the demand for excellent bulkiness and bag-making aptitude (there is no square cracking, bag breaking, etc.) is particularly high.

  As measures for improving the bulkiness of the wrapping paper, the use of a bulking agent and the high blending of mechanical pulp that is rigid and easily forms voids between fibers are being studied. However, since the bulking agent is expensive and has the property of inhibiting or separating the bonds between the fibers, it has a problem of reducing not only the surface strength but also the paper quality strength in the Z-axis (thickness) direction. In addition, the blending of mechanical pulp has the problem of reducing the paper quality strength as kraft paper, although it is possible to obtain bulkiness at low cost.

  Accordingly, various techniques have been developed to provide a wrapping paper and a bulky paper that are improved in bulkiness and are free of tearing and ruled line cracking and excellent in bag-making processability and printability.

  For example, Patent Document 1 discloses that an alkyl ketene dimer is used as an internally added sizing agent in kraft wrapping paper in order to eliminate problems such as insufficient paper size due to waste paper pulp blending, paper dust troubles during printing, and sag of base paper due to moisture absorption. A kraft wrapping paper to which a surface treatment agent composed of oxidized starch and / or polyacrylamide is applied is disclosed. An object of the present invention is to obtain a printing paper that maintains optical characteristics and is bulky and excellent in printability.

  However, although the kraft paper disclosed in Patent Document 1 satisfies the three types of kraft paper defined by JISP4301 (2000), the strength of the original rank is achieved even if the weight is reduced to one basis weight. It does not satisfy.

  Further, Patent Document 2 discloses that the surface of a base paper made of kraft pulp is coated with a coating agent containing heavy calcium carbonate and chestnut pigment, has a sliding inclination angle of 20 degrees or more, and Parker Print Surf rough. Kraft paper having a length of 2.0 to 5.0 μm is disclosed.

  However, the kraft paper disclosed in Patent Document 2 cannot be reduced in weight, and simply provides a coating-type kraft paper that satisfies the three craft standards with the same basis weight and has printability and bag-making suitability. However, it is difficult to satisfy the problems of the present invention.

  Furthermore, Patent Document 3 discloses a low-density paper suitable for printing paper for books, paperback, and other uses by using a specific hardwood pulp fiber system of 15 μm or more and a pulp having a Runkel ratio of 1.0 or more. Is disclosed.

  However, the low-density paper disclosed in Patent Document 3 satisfies the quality as printing paper for books and paperbacks, does not satisfy the problems of the present invention, and has a technical idea that can solve the present invention. There is no disclosure.

  Further, Patent Document 4 contains 10 to 50% by weight of pulverized pulp having an average fiber length of 0.5 mm or less by mechanically pulverizing the coniferous chemical pulp after drying the moisture content to 10% or less. There is a disclosure of a method for producing a bulky paper that is bulky (low density) and excellent in smoothness and strength.

  However, the bulky paper produced by the method disclosed in Patent Document 4 is satisfactory as a printing paper, recording paper, or coating base paper, but does not satisfy the problems of the present invention.

JP 2006-83488 A JP 2008-297635 A JP 2004-169193 A JP 2008-248453 A

  The present invention has been made in view of the above-described background art, and provides a bulky kraft paper for bag-making that has processing suitability and strength as a packaging paper for bag-making and can be reduced in weight despite being bulky. The purpose is to do.

The invention contains two types of pulp, kraft pulp and mechanical pulp,
The proportion of mechanical pulp is 5 to 35% of the total pulp measured in the C dyeing method based on JISP8120 (1998).
Water-soluble resin is applied on at least one side,
The freeness measured according to JIS-P8121 (1995) of the disaggregated pulp disaggregated by the method according to JIS-P8220 (1998) is 500 to 650 cc,
A kraft paper for bag making, characterized in that the density measured according to JISP 8118 (1998) is 0.4 to 0.6 g / m ³ .

  In this invention, the weight average fiber length of the said disaggregated pulp disaggregated by the method based on JIS-P8220 (1998) is 2.0-3.5 mm, The average Runkel ratio of the said disaggregated pulp is 0.9-1. 1 is preferable.

  Moreover, it is preferable that the copper number measured based on JISP8211 (1998) of the said kraft pulp is 50-70, and the brightness measured according to JISP8150 (2004) of the said kraft pulp is 54-60.

Furthermore, containing regenerated particles as a filler, the whiteness of the regenerated particles is 75 to 85%,
It is preferable that the ash content measured based on JISP8251 (2003) is 0.5-3.0 mass%.

  ADVANTAGE OF THE INVENTION According to this invention, although it is bulky, it can provide the bulky craft paper for bag making provided with the processability and intensity | strength as a packaging paper for bag making, and achieving weight reduction.

Recycled particle production equipment flow chart Conceptual diagram of secondary combustion furnace

  Hereinafter, the present invention will be described in more detail.

  Examples of the raw material of the pulp in the present invention include, for example, hardwood unbleached kraft pulp (LUKP), softwood unbleached kraft pulp (NUKP), hardwood half bleached kraft pulp (LSBKP), softwood half bleached kraft pulp (NSBKP), and hardwood sulfite pulp. , Chemical pulp such as coniferous sulfite pulp, stone ground pulp (SGP), pressurized stone ground pulp (PGW), refiner ground pulp (RGP), thermo ground pulp (TGP), chemi-ground pulp (CGP), ground wood pulp (GP) ), Mechanical pulp such as thermomechanical pulp (TMP) is used. Among these, TMP is preferable as the mechanical pulp used in the present invention.

  The kraft paper of the present invention comprises kraft pulp and mechanical pulp. Of the total pulp, the blending ratio of mechanical pulp needs to be 5 to 35%. Preferably, it is 15 to 25%. If the blending ratio of mechanical pulp is less than 5%, the bulky paper thickness that is the object of the present invention cannot be obtained. When the blending ratio of mechanical pulp exceeds 35%, a bulky paper thickness can be obtained, but the tensile strength and tear strength as craft paper for bag making are reduced, and craft paper suitable as bag making paper can be obtained. Can not. The blending ratio of the mechanical pulp is measured by a C dyeing method based on JISP8120 (1998).

  The kraft pulp is preferably softwood unbleached kraft pulp (NUKP). Generally, the kappa number of commercially available softwood unbleached kraft pulp (NUKP) is adjusted to 20-40. In the present invention, it is preferable to use kraft pulp whose copper number is adjusted to 50 to 70. A more preferable kappa number is 55 to 65. When the kappa number is less than 50, the amount of residual lignin in the pulp tends to decrease, and it becomes difficult to satisfy the quality (particularly rigidity) of the pulp that can be used for bag making. The decrease in tear strength cannot be compensated for, making it difficult to use for bag making. If the kappa number exceeds 70, the amount of residual lignin in the pulp tends to increase, and the suppleness of the pulp fibers cannot be obtained, and the angular cracking during bag making occurs, making it suitable for bag making applications. Absent. In addition, since a large amount of resin derived from wood remains, it becomes a cause of dirt on the processing machine during bag making.

  The kappa number is an index of the content of lignin at the time of pulp production, and increases or decreases depending on conditions such as the temperature and time of the chip cooking process. A lower kappa number means that the pulp is bleached, and the brightness is also increased.

  The lightness (L value) of the kraft pulp used in the present invention, in particular the softwood unbleached kraft pulp, is preferably 54 to 60. When the brightness is less than 54, the resin component and lignin derived from wood tend to decrease, and the opacity tends to decrease. Moreover, when the brightness exceeds 60, there is a tendency that the resin content derived from wood and the residual amount of lignin tend to be large, and this tends to cause stains on the processing machine during bag making. Further, since there is a tendency to discolor due to light, it is difficult to stabilize the color tone as a product.

  In a preferred embodiment of the present invention, mechanical pulp (TMP) in the above-described proportion is blended with softwood unbleached kraft pulp (NUKP) to make paper. In that case, the freeness measured based on JIS-P8121 (1995) of the disaggregated pulp disaggregated by the method based on JIS-P8220 (1998) of the craft paper for bag making of the present invention needs to be 500 to 650 cc. is there. 550 to 600 cc is more preferable. When the disaggregation freeness is less than 500 cc, the fiber length of the pulp is shortened, and the fiber diameter of the pulp itself is also thinned. Therefore, the rigidity cannot be maintained as kraft paper for bag making, and the tear strength is reduced. Cannot achieve the goal. Further, if the disaggregation freeness exceeds 650 cc, the fiber length of the pulp becomes long and the fiber diameter of the pulp becomes thick, so that the tensile strength necessary as kraft paper for bag making is lowered. Freeness can be easily adjusted by appropriately setting the beating degree of the pulp to be used.

Factors contributing to paper stiffness (bulk) include the physical structure of the pulp fiber itself, in addition to the basis weight and tension of the paper itself. The pulp fiber has a lumen (lumen), which collapses itself, leading to a cushion function as the entire paper. The ratio between the lumen and the thickness of the outer ring (cell wall) is important for cushioning. Moreover, since the higher the cushioning property, the higher the effect of restoring the bulk with respect to the pressure in various parts of the machine, a kraft paper that is bulky and has excellent paper-making operability can be obtained. Therefore, in this embodiment, it is preferable to optimize the cushioning property by adjusting the average Runkel ratio of the disaggregated pulp disaggregated by a method based on JIS-P8220 (1998). Here, the Runkel ratio R is a value determined by the width (diameter) L of the lumen of the fiber and the thickness t of the cell wall,
R = 2 · t / L
Represented by The Runkel ratio means that the closer the value is to 1.0, the thicker the fiber wall is with respect to the same diameter, and the index represents the rigidity of the fiber. In order to efficiently achieve the object of the present invention, the average Runkel ratio is preferably 0.9 to 1.1, more preferably 0.92 to 1.00. If the average Runkel ratio is less than 0.9, the stiffness of the pulp fiber tends to decrease, and it becomes difficult to ensure the bulk that is the object of the present invention. When the average Runkel ratio exceeds 1.1, the stiffness of the pulp fibers tends to increase, and the entanglement between the fibers tends to decrease, making it difficult to satisfy the strength required for kraft paper for bag making. .

  It becomes more preferable that the selection, classification, and beating treatment of the raw material pulp are not performed as much as possible so that the average Runkel ratio is around 0.9 to 1.1. In addition, selection refers to selection of raw material pulp based on conditions such as obtaining pulp fibers having a relatively large Runkel ratio from pulp made from raw wood or plantation wood obtained from a natural forest, for example. Means. Classification means using a thickener, a screen, a cleaner, etc., and other known SP filters, washers, extractors, filter presses, etc. that are generally used in paper and pulp factories. It means classifying while diluting with water. Beating means beating with a conical refiner, cylindrical refiner, disc refiner, or the like.

  In the kraft paper of this invention, it is preferable that the weight average fiber length of the disaggregated pulp disaggregated based on JISP8220 is 2.0-3.5 mm. Thereby, the strength of the loaded paper according to the present invention can be further increased. More specifically, when the weight average fiber length of the disaggregated pulp is less than 2.0 mm, the tension increases, so that sufficient paper stiffness cannot be obtained, and the bag-making workability tends to deteriorate. On the other hand, when the weight average fiber length of the disaggregated pulp exceeds 3.5 mm, because of the long fibers, the entanglement between the pulp fibers increases and uneven formation occurs, which makes the appearance of the packaging paper worse. A preferred weight average fiber length for securing the paper strength and density for effectively achieving the object of the present invention is 2.2 mm or more and less than 3.0 mm.

  The weight average fiber length referred to in the present invention is a value measured using a fiber length measuring machine fiber lab manufactured by Kayani Automation Co., Ltd., for disaggregated pulp after disaggregation according to JIS P 8220, and the unit is mm. .

  The method for adjusting the fiber length to the above range is not particularly limited, and can be adjusted by a known method such as a single disc refiner (SDR), a double disc refiner (DDR), a classification screen, etc., but can be obtained from planted trees. The raw material pulp can obtain a Runkel ratio that can effectively achieve the object of the present invention, and can be suitably used in the present invention.

  In the raw material pulp of this form, various additives usually blended in kraft paper, such as sizing agent, paper strength enhancer, paper thickness improver, yield improver, etc. Can be used.

  Furthermore, in the present invention, by applying a water-soluble resin to one side or both sides, preferably both sides, of the base paper, it compensates for paper stiffness and strength deterioration accompanying mechanical pulp blending, and more effectively the bag making of the present invention. For craft paper.

  Examples of the water-soluble resin include starch, modified starch, polyvinyl alcohol, casein, carboxymethyl cellulose, acrylic resin, acrylamide, and polyester.

  As the starch, for example, various known ones such as oxidized starch, cationized starch, carboxymethylated starch, pregelatinized starch, phosphate esterified starch, ester-modified starch, urea phosphate-modified starch and unmodified starch are used alone. Or 2 or more types can be mixed and used. Modified starches such as carboxymethyl starch (anionic) and phosphate starch (anionic) exhibit the effect of improving tensile strength and surface strength while penetrating into paper. Of the water-soluble resins, oxidized starch is preferable because it is easy to handle, can provide the intended tensile strength and waist of the present invention, and can effectively achieve the objects of the present invention.

In the case of oxidized starch, the coating amount is preferably 0.8 to 3.5 g / m ^{2 as a} solid amount.

The bag making kraft paper of the present invention preferably has a basis weight of 50 to 120 g / m ² . In order to obtain better bag-making suitability, the basis weight is preferably 60 g / m ² or more, and more preferably 70 g / m ² or more. Here, the basis weight is the weight of the paper per square meter, and changes depending on the thickness and density of the paper.

  Especially in the case of kraft paper for bag making in recent years, in response to the needs of products that are more resource-saving and environmentally friendly, although it is inferior to conventional hand feeling, weight reduction to lower to a lower level of rice tsubo is being promoted Is starting to be seen.

Therefore, although there is a tendency to reduce weight while sacrificing hand feeling, in the present invention, a craft for bag making having a basis weight of 50 to 120 g / m ^{2 that} can be suitably adapted to a known bag making machine as packaging paper for bag making. For paper, it is possible to provide a kraft paper for bag making that can satisfy the bulkiness (thickness) and strength of the conventional basis weight even if the basis weight in the three types of craft is reduced by one rank.

  In order to obtain the printing paper according to the present embodiment, the pulp slurry composed of the raw material pulp, if necessary, various kinds of fillers, internally added sizing agents, fixing agents, yield improvers, cationizing agents, paper strength enhancing agents, etc. For example, a method of adding an additive as appropriate and adjusting a condition such as a pH value and making paper with a normal paper machine such as a long net paper machine or a twin wire paper machine can be employed.

  Examples of fillers include regenerated particles, light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, satin white, aluminum silicate, diatomaceous earth, and silicic acid. White inorganic pigments such as calcium, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide; styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin, melamine Examples thereof include organic pigments such as resins. Of these, regenerated particles are preferred.

  The regenerated particles that can be used in the present invention are regenerated particles produced by the following production method.

  That is, this method refers to the steps of dehydrating, drying, burning and pulverizing the main raw material using the deinking floss separated from the pulp fiber as the main raw material in the deinking step of the used paper processing equipment for producing paper pulp. Then, regenerated particles are obtained, and the drying and combustion steps are performed in the first combustion furnace (internal heat kiln furnace) and the first combustion furnace in which the raw material after the dehydration is dried and burned in series. It has at least a two-stage combustion process having a second combustion furnace (external heat kiln furnace) after burning again the deinked floss that has been burned, and then pulverized to obtain regenerated particles.

  More specifically, hot air of 500 ° C. to 650 ° C. is blown so that the oxygen concentration in the first combustion furnace becomes 0.2% to 20%. In the second combustion furnace, combustion from the first combustion furnace is performed. An object is burned at a temperature of 550 ° C to 750 ° C.

  However, the deinking floss separated from the pulp fiber in the deinking process for producing the used paper pulp contains fine inorganic fine particles as a raw material of the regenerated particles to be obtained by the present invention, and is difficult to use as a used paper pulp. Latex, which is an organic polymer frequently used in fine fibers and coated paper, contains a lot of ink components applied by printing, and in the combustion process, the deinking floss itself generates a combustion reaction (oxidation) and burns itself. There was a problem that heat generation more than the heat treatment with hot air caused excessive combustion of the raw material.

  Such excessive combustion causes yellowing of the raw material due to high-temperature combustion, leading to a decrease in whiteness, melting of the raw material tends to generate hard materials such as gehlenite, increasing the degree of wire wear in the papermaking equipment, In order to form agglomerates by melting, in the subsequent pulverization process, the pulverization energy increases, the processing efficiency decreases, the surface of the raw material is exposed to a high temperature, and is melted before the inside of the raw material. There is a problem that the reaction (oxidation reaction) does not proceed and the organic matter (carbon) remains, resulting in a decrease in whiteness.

  As a means for solving the above problems, the present inventor paid attention to a measure for controlling excessive combustion, and as a result of intensive studies, the deinking floss as a raw material does not self-combust in the first combustion furnace. The combustion temperature of the organic component gas (oxidation) is kept at the furnace temperature of the first combustion furnace that is necessary for releasing the combustion gas (combustible gas) generated by gasification of the organic component contained in the deinking floss. It has been found that promoting only the reaction) can solve the above problems, and has led to the completion of the present invention.

  Furthermore, in order to ensure the oxygen concentration of 0.2% to 20% necessary for burning the combustion gas (combustible gas) in the first combustion furnace, and to prevent excessive combustion of the deinking floss, hot air is supplied. In addition, it has been found that measures to increase the moisture content of the deinking floss as a raw material are effective. According to the knowledge of the present inventor, securing an oxygen concentration of 0.2% to 20% in the first combustion furnace results in an in-furnace environment in which combustion is promoted. It becomes easy.

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

  On the other hand, more preferably, a spiral lifter and / or a parallel lifter parallel to the axial center is disposed on the inner wall of the second combustion furnace from one end side to the other end side thereof, so that the raw material can be evenly distributed. Combustion and uniform quality.

  According to the knowledge of the inventor described above, in the first combustion furnace, the raw material deinking floss is exposed to the combustion reaction at a low combustion temperature, and after obtaining a homogeneous first combustion furnace outlet raw material, the remaining whiteness is lowered. It is necessary to combust as much as possible the carbon component that causes the generation of raw materials, so it is necessary to combust the raw materials slowly, and in order to carry out as uniform combustion as possible continuously, the raw material conveyance in the second combustion furnace It has also been found that a method of appropriately controlling the speed is considered to be the most suitable, and as a means for that, it is possible to use a lifter facility to adjust the feed speed of the raw material. However, since a known lifter is generally manufactured from an iron material, iron is contained in the raw material as a contaminant, which causes a problem of reducing whiteness due to oxidation of iron. Therefore, the present inventor has found a technique that can produce high-quality regenerated particles such as no iron oxidation problem and no reduction in whiteness by providing a stainless steel lifter in the second combustion furnace. It was.

  As the structure of the second combustion furnace, either external heat or internal heat kiln can be adopted as appropriate. The external heat kiln prevents direct burning of the burner directly to the raw material, thus preventing over-burning and uniform firing quality (high whiteness is obtained). On the other hand, the internal heat kiln is insulated by the refractory attached inside. At the same time, it emits far-infrared rays and has the advantage of heating with a small amount of heat. The structure of the second combustion furnace can be appropriately selected in view of these conditions, but it is optimal to provide a lifter for any of the methods.

  On the other hand, conventionally, a deinking sludge is used as a raw material sludge, and a drying process for drying the sludge, and the dried deinking sludge is supplied into the furnace from the upper part of the cyclone type combustion furnace and burned while being swung down. A primary combustion process for obtaining a primary combustion product containing fuel, and a primary combustion product that communicates with the cyclone-type combustion furnace and receives unburned content from the lower end of the primary combustion product. A method for producing a white pigment or white filler from deinking sludge is known, which includes a secondary combustion step of burning until a predetermined whiteness is achieved using the combustion heat of the primary combustion step while promoting contact It is. According to this method, regenerated particles similar to those obtained by the present invention can be obtained.

  However, in this method, a cyclone type fluidized combustion furnace is used, a raw material and air of several tens to several hundreds of microns are supplied from the supply port as a swirling flow, and the raw material is effectively mixed with air by the swirling action of air. In order to burn, the fine particles contained in the raw material are discharged out of the system together with the exhaust gas, the product yield is reduced, and the burning time (heating time) of the deinking floss that is the main raw material is short, so that the unburned portion is reduced. It has been found that there are problems such as being easily generated, and the quality (particularly shape) of the finally obtained combustion product is not constant and the brightness of the combustion product varies.

  Therefore, as a result of repeated studies on means for obtaining regenerated particles with stable quality without causing excessive combustion, the present invention, as described above, includes the first combustion process and the first combustion process as the first combustion process. It has at least two steps of a second combustion step having a second combustion furnace that again burns deinked floss burned in the combustion furnace, and in the first combustion step, a combustion treatment is performed at 300 ° C to 500 ° C. By doing so, it has been found that regenerated particles with stable quality can be produced.

  In a more preferred embodiment, the raw material after dehydration is dried and burned in series, and the combustion time (residence time) in the first combustion furnace by internal heat is preferably 30 minutes to 90 minutes, more preferably 40 minutes to Using a first combustion furnace of 80 minutes, most preferably 50 minutes to 70 minutes, and drying the raw material after dehydration by a preferred internal heat (direct heating) kiln furnace in which the main body is placed horizontally and rotates around the central axis The combustion time (residence time) for performing combustion and then recombusting the combustion product obtained from the first combustion furnace is preferably 60 minutes to 240 minutes, more preferably 90 minutes to 150 minutes, and most preferably 120 minutes to A preferred external heat (indirect heating) kiln furnace using a second combustion furnace with external heat for 150 minutes and rotating around the central axis with the main body placed horizontally, in particular, an external heat electric furnace whose combustion temperature can be easily adjusted, Also adopt the method of burning It is.

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

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

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

  In the conventional first combustion furnace, the moisture content is 40% in order to efficiently burn fine fibers in the raw material, latex that is an organic polymer frequently used for coated paper, ink components applied by printing, and the like. Although the method of dehydrating and drying to less than that and combusting at a high temperature is also described in the above-mentioned publicly known literature, according to the knowledge of the present inventor, the conventional furnace temperature of 300 ° C. to 500 ° C. in the first combustion furnace Compared to the above, by heating at a low temperature, the organic matter contained in the raw material is converted into combustion gas, and the combustion gas is combusted (oxidized). We have found that the contribution to improvement is significant.

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

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

  Here, selection of the combustion furnace which the inventor has focused most on obtaining suitable regenerated particles will be described.

  Conventionally used combustion furnaces can be broadly classified into four types: stalker furnaces (fixed bed), fluidized bed furnaces, cyclone furnaces, and kiln furnaces. As a result of repeated studies on manufacturing, the following matters became clear.

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

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

  As for the cyclone furnace, the fixed carbon in the combustion product cannot be burned sufficiently because it passes through the furnace in an instant, leading to a decrease in whiteness.Furthermore, fine particles are not separated by the cyclone and are exhausted together with the exhaust gas. Since the process goes to the processing step, the yield decreases.

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

  In other words, the external heat kiln furnace has a configuration in which heating equipment is provided outside the kiln furnace, so the structure of the kiln furnace is complicated, and a large amount of heat source is required because the combustion products are dried and burned indirectly. Therefore, when the external heat kiln furnace is used as the first combustion furnace for the drying and combustion treatment of the raw material having a high water content after dehydration according to the present invention, the drying / combustion efficiency is lowered and the productivity is reduced. However, it is difficult to control the temperature and requires a large energy cost, and the cost effectiveness is extremely low.

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

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

  Next, an example of a method for producing regenerated particles according to the present invention will be described with reference to the drawings.

  FIG. 1 is a flow chart of a production facility for regenerated particles according to an embodiment of the present invention. As will be described below, the production process of the regenerated particles includes a dehydration process, a drying / combustion process, and a pulverization process. Further, the deinking floss agglomeration process or granulation process, and a classification process between the processes. Etc. may be provided. This equipment is equipped with various sensors, and controls the state of combustibles, equipment, and processing speed.

  The deinking floss separated from the pulp fiber in the deinking process for producing waste paper pulp (not shown) is subjected to various operations and then dehydrated by a known dehydration equipment (not shown). The raw material after dehydration is preferably in a high water content state of preferably 40% to 90%, more preferably 45% to 70%, and most preferably 50% to 60%.

  The dehydrated raw material 10 is desirably pulverized to a particle size of 40 mm or less by a pulverizer (or pulverizer). The raw material 10 is cut out from the storage tank 12 and charged by a charging machine 15 from one side of the first combustion furnace 14 which is an internal heat kiln furnace in which the main body is placed horizontally and rotates around the central axis. An exhaust gas chamber 16 is provided on one side of the first combustion furnace 14, and an exhaust chamber 18 is provided on the other side. Hot air is blown from the other side of the first combustion furnace 14 through the discharge chamber 18, charged from the one side, and sequentially transferred to the other side as the first combustion furnace 14 rotates. It is designed to dry and burn.

  Here, it is desirable that the hot air blown into the first combustion furnace 14 has an oxygen concentration of 0.2% to 20%. The furnace temperature is preferably 300 ° C to 500 ° C, more preferably 400 ° C to 500 ° C, and most preferably 400 ° C to 450 ° C. Hot air is blown from a hot air generating furnace 20 provided with a burner 20A.

  From the exhaust gas chamber 16, exhaust gas subjected to drying and combustion is sent into the recombustion chamber 22. The fine powder of the combustion material contained in the exhaust gas is discharged from the lower part of the exhaust gas chamber 16 and reused. The exhaust gas is recombusted by the burner in the recombustion chamber 22, precooled by the precooler 24, passed through the heat exchanger 26, and discharged from the chimney 30 by the induction fan 28. Here, after raising the temperature of the outside air, the heat exchanger 26 is sent to the hot air generating furnace 20 and used for the hot air blown from the first combustion furnace 14 to recover the heat of the exhaust gas from the exhaust gas chamber 16. It is like that. The treatment of exhaust gas is effective for removing harmful substances contained in the exhaust gas.

  Combustion products that have undergone drying and combustion treatment in the first combustion furnace 14 are charged into a second combustion furnace 32 that is an external heat kiln furnace in which the main body is placed horizontally and rotates around the central axis. The particle size of the combusted material to be charged is preferably 40 mm or less. As a heat source in the second combustion furnace 32, it is preferable to use an electric adjustment that allows easy temperature control in the second combustion furnace 32 and easy temperature control in the longitudinal direction. Therefore, the first combustion is indirectly performed by an electric heater. It is desirable to be an external heating type combustion furnace in which the combustion product obtained from the furnace 14 is burned again.

  In the second combustion furnace 32, the oxygen concentration is preferably 5% to 20%, more preferably 10% to 20%, and most preferably by an air or oxygen supply mechanism (not shown) for adjusting the oxygen concentration. It burns so that it may become 10% -15%. As temperature, Preferably it is 550 to 780 degreeC, More preferably, it is 600 to 750 degreeC. The residence time in the second combustion furnace 32 is preferably 60 minutes to 240 minutes, more preferably 90 minutes to 150 minutes, and most preferably 120 minutes to 150 minutes, and the remaining carbon is completely burned.

  The regenerated particles that have been burned are cooled by a cooler 34, and then sorted by a particle size sorter 36 such as a vibration sieve, and the combustion is adjusted to a target particle size in a grinding process using a wet grinding machine or the like. The material is temporarily stored in the combustion product silo 38 and is sent to the application destination of the pigment or filler.

  In addition, although the case where deinking floss was used as a raw material was illustrated, even if it is a combustion thing which used as a raw material what mixed other papermaking sludges, such as papermaking sludge in a papermaking process, with deinking floss as a main raw material Good.

  As mentioned above, although the outline | summary of the manufacturing process of regenerated particle was demonstrated, the detail and an application example are demonstrated below.

〔material〕
In the used paper pulp manufacturing process, in order to continuously produce used paper pulp of stable quality, used paper is selected and selected, and used paper of a certain quality is used. For this reason, the types, ratios, and amounts of inorganic substances brought into the used paper pulp manufacturing process are basically constant. Moreover, even when plastics such as vinyl and film, which cause fluctuations in unburned materials in the method for producing regenerated particles, are contained in the waste paper, these foreign matters are not before the deinking process to obtain deinking floss. Can be removed in stages. Accordingly, the deinking floss is a raw material for producing regenerated particles having extremely stable quality as compared with paper sludge generated in other processes such as a factory drainage process and a papermaking raw material preparation process.

  The deinking floss referred to in the present invention refers to what is separated from pulp fibers in the deinking process for removing ink adhering to the used paper in the used paper processing process for producing the used paper pulp.

[Dehydration process]
For further dehydration of the deinking floss, known dehydration means can be used as appropriate. In one example of the present embodiment, the deinking floss is dehydrated by separating water from the deinking floss by a screen serving as a dewatering unit. In the screen, the deinking floss dehydrated to 90% to 97% is preferably sent to, for example, a screw press and further dehydrated to a predetermined moisture.

  If the moisture content of the raw material 10 after dehydration exceeds 70%, the temperature of the drying / combustion treatment in the first combustion furnace 14 will be lowered, the energy loss for heating will be great, and the non-uniform combustion of the raw material 10 will occur. It becomes easy and it becomes difficult to advance uniform combustion. Furthermore, moisture in the exhaust gas to be discharged increases, and there is a problem in that the recombustion treatment efficiency in dioxin countermeasures is reduced and the load on the exhaust gas treatment facility is large. Moreover, when the moisture content of the raw material 10 after dehydration is as low as less than 40%, it causes excessive combustion of the deinking floss. It also contributes to reduction of dehydration energy.

  As has been clarified in the above description, if dewatering of the deinking floss is performed in a multi-stage process and abrupt dewatering is avoided, the outflow of inorganic substances can be suppressed and there is no possibility that the deinking floss flock becomes too hard. In the dehydration treatment, an auxiliary agent for improving the dehydration efficiency such as an aggregating agent for aggregating the deinking floss may be added, but it is preferable to use an aggregating agent that does not contain iron. When iron is contained, it causes a problem of lowering the whiteness of the regenerated particles due to oxidation of iron.

  The deinking process of deinking floss is preferably adjacent to the process for producing regenerated particles in the present invention in terms of production efficiency, but a facility is provided in advance adjacent to the used paper pulp manufacturing process to transport the dehydrated product. It is also possible to carry it to a fixed quantity feeder by means of conveyance such as a truck or a belt conveyor, and supply it to the drying / combustion process from this fixed quantity feeder.

  In the operation of supplying the raw material 10 after dehydration to the first combustion furnace 14, the average particle size is preferably 40 mm or less, more preferably 3 mm to 30 mm, most preferably 5 mm to 20 mm by a pulverizer (or pulverizer). Adjusted to be in range. Further, it is more preferable to grind so that the ratio of the average particle diameter is 50 mm or less is 70% by weight or more. In order to achieve a combustion treatment that does not cause a heat change of the calcium carbonate contained in the deinking floss, it is preferable that the particle diameter of the raw material is uniform. However, if the average particle diameter is less than 3 mm, overburning easily occurs and exceeds 40 mm. This is because the average particle size has a problem that it is difficult to achieve uniform combustion up to the raw material core.

  The ratio between the average particle size and the particle size was measured using a sample solution sufficiently dispersed by a stirring type disperser. The particle diameter in each combustion process was measured with a metal plate sieve based on JIS Z8801-2: 2000.

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

  That is, in the main drying / combustion step, the dehydrated product is dried and burned gently from the supply port to the discharge port by drying and burning in the first combustion furnace 14 whose body is horizontally placed and rotates around the central axis. Combustion of organic components can be performed, pulverization of combustibles can be suppressed, and the degree of combustion of dehydrated products having various properties such as formation of aggregates, hard and soft, and particle alignment can be stably performed. In addition, the drying can be divided into separate steps and a blow-up type dryer can be inserted.

  Here, the hot air blown into the first combustion furnace 14 has an oxygen concentration of preferably 0.2% to 20%, more preferably 1% to 17%, and most preferably 7% to 15%. Yes.

  Since the oxygen concentration is consumed by combustion (oxidation) of the raw material 10, the oxygen concentration varies depending on the state of combustion. If the oxygen concentration is excessively low, it is difficult to achieve sufficient combustion. The oxygen in the first combustion furnace 14 is consumed by the combustion of the raw material 10 and the oxygen concentration is lowered. However, by blowing or exhausting oxygen-containing gas such as air by a hot air generator for burning, etc. The oxygen concentration can be maintained and adjusted, and further, the temperature in the first combustion furnace 14 can be finely adjusted by blowing or exhausting the oxygen-containing gas, and the raw material 10 is uniformly burned uniformly. be able to.

  The furnace temperature of the first combustion furnace 14 is preferably 300 ° C to 500 ° C, more preferably 400 ° C to 500 ° C, and most preferably 400 ° C to 450 ° C. In the first combustion furnace 14, it is preferable to combust in a temperature range of 300 ° C. to 500 ° C. for the purpose of gently burning organic matter that can be easily combusted and suppressing generation of residual carbon that is difficult to combust. When the temperature is excessively low, the organic matter is not sufficiently combusted. When the temperature is excessively high, overcombustion occurs, and calcium oxide is easily generated due to decomposition of calcium carbonate. Furthermore, when the temperature of the hot air is 500 ° C. or higher, drying / combustion proceeds locally faster than the alignment of the combustibles having various properties such as hard and soft, so that the unburned particles on the particle surface and inside It becomes difficult to make the difference in rate small and uniform.

  Hot air is blown from a hot air generating furnace 20 provided with a burner 20A.

  From the exhaust gas chamber 16, exhaust gas subjected to drying and combustion is sent into the recombustion chamber 22. The fine powder is discharged from the lower part of the exhaust gas chamber 16 and is mixed with the raw material and reused.

  The exhaust gas is recombusted by the burner in the recombustion chamber 22, precooled by the precooler 24, passed through the heat exchanger 26, and discharged from the chimney 30 by the induction fan 28. Here, the heat exchanger 26 raises the outside air and then sends it to the hot air generating furnace 20 to be used for the hot air blown from the first combustion furnace 14 so as to recover the heat of the exhaust gas from the exhaust gas chamber 16. It has become.

  The first combustion furnace 14 preferably burns with a residence time of 30 minutes to 90 minutes under the above conditions in order to slowly burn the easily combustible organic substances contained in the deinking floss and suppress the formation of residual carbon. It is preferable to make it. Further, 40 minutes to 80 minutes are more preferable in terms of organic combustion and production efficiency, and 50 minutes to 70 minutes are most preferable from the viewpoint of ensuring constant quality. If the combustion time is less than 30 minutes, sufficient combustion is not performed and the proportion of remaining carbon increases. When the combustion time exceeds 90 minutes, thermal decomposition of calcium carbonate due to overcombustion of the raw material 10 occurs, and the regenerated particles obtained become extremely hard.

  In particular, it is preferable to dry and burn the unburned rate of the combustion product supplied in the second combustion step of the next step to 2 to 20% by mass, more preferably 5 to 17% by mass, and most preferably 7%. It is mass%-12 mass%.

  By setting the unburned rate to 2 mass% to 20 mass%, the combustion in the second combustion process can be efficiently performed in a short time, and the hardness is low due to the stable heating in the external heating furnace. 80% or more, and at least 70% or more of high whiteness combustion products can be obtained. If the unburned material is less than 2% by mass, the energy cost in the first combustion furnace 14 is high, and the hardness of the combustion material may be relatively high. In some cases, the quality may be degraded such as a decrease in the degree.

[Second combustion process]
The combustion product that has undergone drying and combustion processing in the first combustion furnace 14 has an external heat jacket 31 in which the main body is placed horizontally and rotates around the central axis through the transfer flow path, and is a second combustion furnace 32 that is an external heat kiln furnace. Is charged.

  In the second combustion furnace 32, the combustion material is heated by external heat, and the transfer of the raw material 10 in the furnace is controlled by a lifter provided on the inner wall of the kiln furnace, so that the combustion is performed more slowly. Burn the unburned content.

  In the combustion in the second combustion furnace 32, residual organic matter that could not be combusted in the first combustion furnace 14, for example, residual carbon, is burned, so that the particles are smaller than the particle diameter of the raw material 10 supplied in the first combustion furnace 14. It is preferable to use a combustion product adjusted to a diameter. The particle size of the burned product after the drying / combustion step is adjusted so that the average particle size is preferably 10 mm or less, more preferably 1 mm to 8 mm, and most preferably 1 mm to 5 mm.

  If the average particle diameter at the entrance of the second combustion furnace 32 is less than 1 mm, there is a risk of overcombustion, and if the average particle diameter exceeds 10 mm, the remaining carbon is difficult to burn and combustion does not proceed to the core. It causes a problem that the whiteness of the obtained regenerated particles is lowered. In order to ensure stable production in the second combustion furnace 32, it is preferable to adjust the particle diameter so that the combustion product having an average particle diameter of 1 mm to 8 mm is 70% or more. Therefore, it is beneficial in terms of the possibility of practical use in terms of uniforming the quality of the obtained regenerated particles. Furthermore, when the classification is performed after drying as in the present embodiment, the combustion product of small-diameter particles can be surely removed, and the processing efficiency is improved.

  As an external heat source in the second combustion furnace 32, an electric heating type electric furnace in which temperature control in the second combustion furnace 32 is easy and temperature control in the longitudinal direction is easy is suitable. The combustion furnace 32 is desirable.

  By using electricity for the external heat, it becomes possible to finely adjust the temperature and control the internal temperature uniformly, control the degree of combustion of dehydrated products with various properties such as formation of aggregates, hard and soft, and granulation Alignment can be performed stably.

  Furthermore, the electric furnace can be provided with a temperature gradient arbitrarily by providing a plurality of electric heaters in the flow direction of the furnace, and can maintain the temperature of the combustion product for a certain period of time. Residual organic components in the combustion product that has passed through the first combustion furnace 14, particularly residual carbon, can be brought to zero as much as possible without causing uncombusted carbon dioxide to decompose in the second combustion furnace 32. Thus, regenerated particles with high whiteness can be obtained.

  In the second combustion furnace 32, the oxygen concentration is preferably set to 5% to 20%, more preferably 10% to 20%, and most preferably 10% to 15%. The oxygen concentration can be determined by controlling the amount of oxygen or air input to the second firing furnace (external heat kiln furnace) 32 by an appropriate means (illustration of a specific embodiment is omitted).

  If the oxygen concentration in the second combustion furnace 32 is less than 5%, there arises a problem that the combustion of the remaining carbon that is difficult to burn does not proceed.

  As temperature, Preferably it is 550 to 780 degreeC, More preferably, it is 600 to 750 degreeC.

  As described above, the second combustion furnace 32 needs to burn the residual organic matter that could not be burned in the first combustion furnace 14, particularly the remaining carbon, so that it is burned at a higher temperature than the first combustion furnace 14. When the combustion temperature is less than 550 ° C., it is difficult to sufficiently burn the residual organic matter. When the combustion temperature exceeds 780 ° C., the oxidation of calcium carbonate in the combustion product proceeds and the particles are hard. Problem arises.

  The residence time is preferably 60 minutes to 240 minutes, more preferably 90 minutes to 150 minutes, and most preferably 120 minutes to 150 minutes. In particular, the remaining carbon must be burned slowly at a high temperature that does not cause the decomposition of calcium carbonate as much as possible. If the residence time is less than 60 minutes, the remaining carbon is burnt in a short time, and 240 minutes. If it exceeds 1, the problem of decomposition of calcium carbonate occurs.

  Furthermore, it is preferable that combustion be performed in a residence time of 60 minutes or more in order to prevent overcombustion and ensure production in 240 minutes or less in stable production of combustion products.

  The average particle size of the combustion product discharged from the second combustion furnace 32 is preferably adjusted to 10 mm or less, more preferably 1 mm to 8 mm or less, and most preferably 1 mm to 4 mm.

  The regenerated particles whose combustion has been completed are preferably aggregates (regenerated particle aggregates), and after being cooled by the cooler 34, those having a target particle size are combusted by a particle size sorter 36 such as a vibration sieve. It is temporarily stored in the silo 38 and sent to the application destination of the pigment and filler.

  In addition, although the case where the deinking froth was used as the raw material 10 was illustrated, it may be a combustion product obtained by appropriately mixing other papermaking sludge such as papermaking sludge in the papermaking process with the deinking floss as the main raw material.

[Crushing process]
In the method for producing regenerated particles based on the present embodiment, if necessary, a known dispersion / pulverization step is further provided, and a pigment for coating and a filler for internal addition are prepared by appropriately finely pulverizing to a necessary particle size. Can be used as

  In one example, the particles obtained after combustion are pulverized using a dry pulverizer such as a jet mill or a high-speed rotary mill, or a wet pulverizer such as an attritor, a sand grinder, or a ball mill. Regarding the optimum particle size for fillers, pigment applications, etc., the regenerated particles of this embodiment preferably have an average particle size of 2 to 5 μm.

  This is considered to be because the bulky effect is improved because the average particle size is larger than that of conventional calcium carbonate. Talc and clay have an average particle size larger than that of recycled filler and can be expected to have a bulky effect.

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

[Attached process]
In this production facility, in order to obtain more stable quality, it is preferable to classify the particle size of the regenerated particles uniformly in each step, and feed back coarse and fine particles to the previous step. The quality can be further stabilized.

  In addition, it is preferable to granulate the deinked floss that has been subjected to dehydration in the previous stage of the drying process, and it is more preferable to classify the granulated product so that the particle diameter is uniform, The quality can be further stabilized by feeding back the fine granulated particles to the previous process. In granulation, a known granulation facility can be used, and facilities such as a rotary type, a stirring type and an extrusion type are suitable.

  As the raw material 10 of this production method, it is preferable to remove in advance other than what can be a raw material of regenerated particles, for example, sand with a pulper, a screen, a cleaner, etc. in the previous stage leading to the deinking process of the used paper pulp manufacturing process, It is preferable in terms of removal efficiency to remove plastic foreign substances, metals and the like. In particular, iron contamination is a causative agent for reducing the whiteness of fine particles due to oxidation, so it is recommended to avoid iron contamination and selectively remove it. Design or lining each process with materials other than iron, It is preferable to prevent iron from being mixed into the system due to abrasion or the like, and to further remove iron selectively by installing a high magnetic material such as a magnet in the drying / classifying equipment.

  Furthermore, the regenerated particles produced by the method for producing regenerated particles according to the present embodiment preferably have a ratio of calcium, silica and aluminum in terms of oxides of 30 to 82: 9 to 35 in elemental analysis of fine particles using an X-ray microanalyzer. : 9-35, more preferably 40-82: 9-30: 9-30, most preferably 60-82: 9-20: 9-20.

  By including calcium, silica, and aluminum in a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxides, the specific gravity is light and excessive aqueous solution absorption can be suppressed, so that the dehydrating ability in the dehydration process can be reduced. It is good and can reduce the proportion of unburned matter in the drying / combustion process and the risk of excessive hardness due to sintering in the combustion process.

  As a method for adjusting the ratio of the present embodiment, the main point is to adjust the raw material composition in the deinking floss, but in the drying / combustion process and the combustion process, the coating floss and preparation process with a clear origin It is also possible to adjust by means of containing floss in the process by spraying or the like, or means of containing incinerator scrubber lime.

  For example, using deinked floss as the main raw material, neutral papermaking drainage sludge and wastewater sludge from the coated paper manufacturing process are used to adjust calcium in the regenerated particles, and opacity improvers are used to adjust silica. Newspaper manufacturing wastewater sludge with a large amount of white carbon added, papermaking wastewater sludge that uses an acid papermaking system and other sulfuric acid bands to adjust aluminum, and high-quality papermaking process that uses a lot of clay Drainage sludge in can be used.

  In addition, the regenerated particles obtained by this production method have a weight loss (rate) of 50% or more in the decomposition (change to calcium oxide) of calcium carbonate that occurs in the vicinity of 700 ° C. in the differential thermal analysis using the differential thermal thermogravimetric simultaneous measurement device. As described above, it is preferable to control the combustion of the deinking froth based on the present embodiment, since the progress of the oxidation of the calcium component can be suppressed more accurately and the particles can be prevented from becoming hard.

[About the lifter of the second combustion furnace (external heat kiln furnace)]
As described above together with the reason for adoption, parallel to the inner wall of the secondary combustion furnace (external heat kiln furnace) 32 parallel to the spiral lifter and / or the axis from one end side to the other end side. By disposing the lifter, it is possible to achieve uniform combustion of the raw material 10 and uniform quality.

  For this secondary combustion furnace (external heat kiln furnace) 32, a known rotary combustion apparatus as shown in FIG. 2 (a) with its internal structure and FIG. Used for.

  That is, the secondary combustion furnace (external heat kiln furnace) 32 is configured to be rotationally driven by a rotational drive means (not shown), and has a charging part 32a at one end and a discharge part at the other end. (Not shown) is provided, and the other end is provided with a combustion burner (not shown) for introducing combustion gas into the cylindrical main body 32b. The inner surface of the fireproof wall 32c on the side of the insertion portion 32a of the cylindrical main body 32b has a plurality of spirals (eight in the illustrated example) that are inclined at an inclination angle of 45 ° to 70 ° with respect to the axis of the cylindrical main body 32b. A cylindrical lifter 32d protrudes at equal intervals through a bracket 32e, and a parallel lifter 32f of an appropriate length parallel to the axial center of the cylindrical main body 32b is provided at the other end side in the circumferential direction. A plurality (eight in the illustrated example) are provided at intervals, and a plurality of rows (eight in the illustrated example) bracket 32g are provided in the axial direction.

  The fireproof wall 32c is preferably made of fireproof castable or fireproof brick, and the helical lifter 32d and the parallel lifter 32f are made of metal such as a stainless steel plate having heat resistance, for example. Therefore, durability and strength can be sufficiently secured without using an expensive heat-resistant material, and heat transfer efficiency is higher than that of a refractory lifter, so that the heat efficiency can be further improved. In particular, it is desirable that the spiral lifter 32d and the parallel lifter 32f are arranged in this order from the combusted material input portion 32a side to the discharge side as described above.

  According to the secondary combustion furnace (external heat kiln furnace) 32 configured as described above, the content charged from the charging portion 32a is first appropriately amounted toward the other end side by the spiral lifter 32d. While being lifted and dropped each time, the organic components resulting from the raw material 10 efficiently come into contact with the combustion gas (combustible gas) generated by gasification, and then lifted and dropped by the parallel lifter 32f. By repeating the operation to perform efficient contact with the combustion gas (combustible gas), the contents can be combusted with high heat exchange efficiency. In particular, by controlling the amount of the content fed into the parallel lifter 32f by the spiral lifter 32d, the content can be properly lifted and dropped at the parallel lifter 32f, and the content can be burned uniformly and efficiently. Can be done automatically. Further, since there is no fear of damage to the refractory, there is no decrease in the purity of the fired product, and its production capacity can be improved.

  In the above-described embodiment, the spiral lifter 32d and the parallel lifter 32f are provided side by side, but only one of them may be provided as necessary.

  The regenerated particles obtained as described above have a high whiteness of preferably 75 to 85%, more preferably 80 to 85%, and little variation in whiteness. In addition, when the regenerated particles obtained by the production method described above are used in the kraft paper for bag making, compared to the case of using conventionally known regenerated particles and calcium carbonate which is a commercially available filler, there is a decrease in paper strength. A kraft paper which is small and bulky and can be used as a kraft paper for bag making can be obtained.

  The whiteness of the regenerated particles was measured with a whiteness meter KR-III type manufactured by Kumagaya Riki Kogyo Co., Ltd. in accordance with US TAPPI standard method T-646 OS-75.

  The regenerated particles obtained by the production method according to the present invention have an average particle size larger than that of conventionally known calcium carbonate (0.3 to 2.0 μm), and the regenerated particles are fixed between fibers. In addition, the bulkiness effect is improved, and since the aluminum in the regenerated particles is cationic, the fixing property to the fiber is strong, the bulkiness effect and the surface strength are improved, and as a result, a kraft paper with less decrease in paper strength is provided. Is believed to be able to.

  In the kraft paper of the present invention, the content of aluminum oxide is preferably 10 to 35% by mass, more preferably 15 to 25% by mass, of the total inorganics including the inorganics brought in from the regenerated particles. When the aluminum content is less than 10%, the improvement in fixability is reduced. On the other hand, if the aluminum content exceeds 35%, the cationicity becomes too strong and reacts with the papermaking chemicals, which may cause agglomerates and black foreign matters such as pitch, which is not desirable.

  In this embodiment, the regenerated particles as described above can be used alone, or such regenerated particles and heavy calcium carbonate, light calcium carbonate, talc, clay, kaolin, titanium dioxide, which are usually used as internal fillers. In addition, at least one filler selected from inorganic fillers such as synthetic silica and aluminum hydroxide, and synthetic polymer fine particles such as polystyrene resin and urea formaldehyde resin can be used in combination. Of course, these two or more types can be used in combination.

  The content of recycled particles in the base paper (relative to the base paper) is preferably 0.5 to 3.0% by mass, more preferably 0.5 to 1.8% by mass. When the content exceeds 3.0% by mass, the density decreases and the bulk does not increase. When the content is less than 0.5% by mass, the whiteness decreases.

  Examples of internally added sizing agents include rosin sizing agents for acidic papermaking, modified rosin sizing agents for neutral papermaking, alkenyl succinic acid sizing agents, alkyl ketene dimer sizing agents, alkenyl succinic anhydride sizing agents, and wax sizing agents. Styrene resin sizing agent, olefin resin sizing agent, styrene-acrylic resin sizing agent, higher fatty acid sizing agent, cationic polymer sizing agent, oxidized starch and the like.

  In addition to the above-mentioned various additives, a method of adding a bulking agent to the raw pulp slurry and improving the bulk of the resulting printing paper has been tried, but the bulking agent is mainly based on the Z-axis strength of the paper. In order to reduce the paper strength, it is preferable to refrain from using it.

  In order to effectively achieve the object of the present invention without using a bulking agent, the ash content measured according to JIS P 8251 (2003) is preferably 0.5 to 3.0% by mass. It is preferable to add the filler mentioned above so that it may become. More preferably, regenerated particles produced by the production method are preferred. If the ash content is less than 0.5% by mass, the paper formation tends to deteriorate, and the printability tends to deteriorate. On the other hand, when the ash content exceeds 3.0% by mass, it becomes difficult to obtain a kraft paper for bag making which is bulky and has excellent processability and strength as a bag making application.

  Note that, when the bulky packaging paper for bag making according to the present embodiment is applied to, for example, offset printing, since dampening water is used in such offset printing, the wrapping paper of the present invention is appropriately sized (water absorption resistance). Property). By maintaining such sizing properties satisfactorily, it is possible to more sufficiently suppress fears such as an increase in the amount of dampening water transfer, paper elongation, poor wet inking, and color misregistration.

  In order to control the sizing property, an internal sizing agent as described above is added to the raw pulp slurry, and the internal sizing agent is contained in the wrapping paper of the present invention at the same time as the paper making, or after the paper making, two rolls It is preferable to apply a surface sizing agent to the surface of the wrapping paper of the present invention using a coating machine such as a size press or a gate roll coater, or at least one of them. As the surface sizing agent, for example, those exemplified as the internal sizing agent can be used.

  For example, when the internal additive sizing agent is used, in order to impart sufficient sizing properties to the resulting wrapping paper of the present invention and further improve the moisture resistance and water resistance, 0.1 parts by mass or more with respect to 100 parts by mass of the raw material pulp. Further, it is preferable to blend 0.3 parts by mass or more, and in order to prevent the ink from drying and drying on the surface of the wrapping paper of the present invention from being deteriorated and the printing operability from being deteriorated, It is preferable that it is 1 mass part or less with respect to 100 mass parts of pulp, and also 0.8 mass part or less.

Further, for example, when the surface sizing agent is used, in order to impart sufficient sizing properties to the resulting wrapping paper of the present invention and to improve the moisture resistance and water resistance, the coating amount on the wrapping paper of the present invention is reduced per side. It is preferably 0.04 g / m ² or more, more preferably 0.06 g / m ² or more, and there is a possibility that the ink drying on the surface of the wrapping paper of the present invention does not deteriorate and the printing operability is deteriorated. In order to avoid this, it is preferable that the coating amount on the printing paper is 0.20 g / m ² or less, more preferably 0.18 g / m ² or less per side.

The density of the wrapping paper of the present invention according to this embodiment, measured according to “Thickness and Density Test Method” described in JIS P 8118, is 0.4 to 0.6 g / cm ³ . The density is necessary in combination with the printability, and the rigidity (vertical) measured in accordance with the “stiffness test method by paper Clark stiffness tester” described in JIS P 8143 is good printing workability and feel. terms impart sensitive, also maintaining a sufficient printability is preferably about 70~180cm ^3/100.

  Thus, the bulky wrapping paper for bag making according to the present embodiment is excellent in printability despite being light and bulky.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

  A pulp slurry in which the unbleached kraft pulp of conifers beaten to 650 mL of CSF and mechanical pulp (TMP) beaten to 250 mL of CSF were blended so that the blending ratio of mechanical pulp by the C dyeing method was the ratio (%) shown in Table 1 Aluminum sulfate (sulfuric acid band, manufactured by Showa Chemical Industry Co., Ltd.) with a solid content of 0.28% by mass, neutral rosin sizing agent (product number: NS74, manufactured by Harima Kasei Co., Ltd.) with a solid content of 0.1 % By weight and a paper strength enhancer (Product No .: Amilofax TS2600, manufactured by AVEBEb.a. Inc.) is added in an amount of 0.5% by weight as a solid content, and regenerated particles having a whiteness of 83.9% Is added to 0.8 mass%, then the wire part, press part, pre-dryer part, size part, after-dryer part, calendar part, reel part and wire Paper making was performed using a papermaking system including a lower part.

On both sides of the obtained paper, a sizing agent (product number: SE2064, manufactured by Seiko PMC Co., Ltd.) 0.15 g / m ² , oxidized starch (product number: MS3800, Nippon Food Processing Co., Ltd.) using a gate roll coater. Co., Ltd.) was applied at a solid content of 2.0 g / m ² to obtain a test paper.

  Each test paper was obtained as described in Table 1. The results are shown in Table 1. The evaluation method is as follows. Freeness, fiber length, and Runkel ratio were adjusted using a commercially available disintegrator, beater, and the like. The copper value was also adjusted based on the above description. The ash content was adjusted by changing the amount of regenerated particles added.

In each Example, the following water-soluble resins were used.
Tapioca starch: SB GUM-EVOSB gum, Sanki Co., Ltd. PVA: JF-04, Nihon Vinegar Bipvar Co., Ltd. Sex PAM: Haricoat G-51, Harima Kasei Co., Ltd. Cornstarch: CHARGEMASTER R462 Charge Master, Sanki Co., Ltd. potato starch: Mermaid M-350B, Sanki Co., Ltd. Latex: Nalstar SR-103, Nippon A & L Co., Ltd. (copper number)
Measured according to JIS P 8211 (1998) “Pulp-Kappa number test method”.

(brightness)
It measured with the spectral white photometer "EPR-80WX" (made by Tokyo Denshoku Co., Ltd.).

(Disaggregation freeness)
Measured in accordance with JIS P 8220 (1998) “Pulp-Disaggregation Method” and JIS P 8121 (1995) “Pulp Freeness Test Method”.

(Basis weight)
The measurement was performed according to the method described in JIS P 8124 “Paper and paperboard—basis weight measurement method”.

(Weight average fiber length)
The obtained test paper was disaggregated by a method based on JIS-P8220 (1998). TAPPI NO. 52, measured with a fiber length measuring instrument fiber laboratory manufactured by Kayani Automation.

(Average Runkel ratio)
The obtained test paper was disaggregated by a method in accordance with JIS-P8220 (1998), and the obtained disaggregated pulp was measured with a fiber length measuring machine fiber lab manufactured by Kayani Automation Co. Calculated from the diameter.

(Tensile strength)
Measurement was performed in accordance with JIS P8113.

(Tear strength)
It measured based on JIS P8116.

(Ability to make bags <paper stiffness>)
Using an automatic bag making machine (model number: 136T + 504TH, manufactured by Neurong Kogyo Co., Ltd.), a square bottom bag was processed from kraft paper, the state of processing speed was examined, and evaluation was performed based on the following evaluation criteria.

〔Evaluation criteria〕
A: The processing state is uniform throughout and can be processed at the same speed as conventional unbleached kraft paper.
○: Although the processing state is slightly inferior, it can be processed at the same speed as conventional unbleached kraft paper.
(Triangle | delta): Since the tendency for a processing state to fall is seen, it is necessary to reduce a processing speed compared with the conventional unbleached kraft paper. Waves are observed in the glued part.
X: The processing state is not uniform, and no improvement is seen even if the processing speed is greatly reduced.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

(Suitability for bag making <square cracking>)
Using the aforementioned automatic bag making machine, square bottom bags were processed from kraft paper, the state of square cracks at the folded portion of the square bottom bags was examined, and evaluated based on the following evaluation criteria.

〔Evaluation criteria〕
A: In the processed square bottom bag, the frequency of occurrence of square cracks is less than that of conventional unbleached kraft paper.
○: In the processed square bottom bag, the frequency of occurrence of square cracking is the same as that of conventional unbleached kraft paper.
Δ: In the processed square bottom bag, the frequency of occurrence of square cracks is the same as that of conventional unbleached kraft paper, but when one corner has multiple corner cracks, or the frequency of occurrence of square cracks is that of conventional unbleached kraft paper When it is less than double and the size of one bag is light.
X: In the processed square bottom bag, the frequency of occurrence of square cracks is more than double that of conventional unbleached kraft paper.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

DESCRIPTION OF SYMBOLS 10 Raw material 12 Storage tank 14 1st combustion furnace 15 Charger 16 Exhaust gas chamber 18 Exhaust chamber 20 Hot air generating furnace 20A Burner 22 Recombustion chamber 24 Precooler 26 Heat exchanger 28 Induction fan 30 Chimney 32 Second combustion furnace 34 Cooler 36 Particle size sorter 38 Combustion product silo

Claims (4)

Contains two types of pulp and filler, kraft pulp and mechanical pulp,
The kraft pulp is unbleached kraft pulp,
The proportion of mechanical pulp is 5 to 35% of the total pulp, and the proportion of kraft pulp is 65 to 95% , measured in the C dyeing method according to JISP 8120 (1998).
Water-soluble resin is applied on at least one side,
The water-soluble resin is oxidized starch;
The freeness measured according to JIS-P8121 (1995) of the disaggregated pulp disaggregated by the method according to JIS-P8220 (1998) is 500 to 650 cc,
The weight average fiber length of the disaggregated pulp is 2 to 3.5 mm,
Kraft paper for bag making, characterized in that the density measured according to JISP 8118 (1998) is 0.4 to 0.6 g / cm ³ .   The kraft paper for bag making according to claim 1, wherein an average Runkel ratio of the disaggregated pulp disaggregated by a method according to JIS-P8220 (1998) is 0.9 to 1.1.   The kappa number measured according to JISP8211 (1998) of the kraft pulp is 50 to 70, and the brightness measured according to JISP8150 (2004) of the kraft pulp is 54 to 60. 2. Kraft paper for bag making according to 2. As the filler, deinked floss discharged from the waste paper processing step is used as a main raw material, and it is obtained through the steps of dehydration, drying, combustion, and pulverization. The drying and combustion steps are performed in the first combustion furnace and the second combustion furnace. And having regenerated particles obtained at a temperature of 300 ° C. to 500 ° C. in the first combustion furnace, wherein the whiteness of the regenerated particles is 75 to 85%,
The kraft paper for bag making according to any one of claims 1 to 3, wherein an ash content measured according to JISP8251 (2003) is 0.5 to 3.0 mass%.

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