JP5508748B2 - Kraft paper - Google Patents

Description

  The present invention relates to a kraft paper made mainly from unbleached kraft pulp, and more particularly to a lightweight and bulky kraft paper having suitable processing properties as a packaging paper for bag making.

  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. The paper for bag making is desired to have processing suitability and strength that can be used for bag making even if one standard US tsubo is down.

  Unbleached kraft paper is often used as a paper type for bag making (lightweight packaging, light packaging such as square-bottom bags and handbags). In bag making applications, strong paper strength is required in all cases, so unbleached kraft paper for heavy bags is made from unbleached kraft pulp, and unbleached kraft paper for light packaging is unexposed to conifers. It is made only from unbleached kraft pulp that uses kraft pulp as the main raw material and some hardwood unbleached kraft pulp.

  On the other hand, as an environmentally friendly unbleached packaging paper for packaging, those containing waste paper pulp are 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.

  For packaging paper that requires high strength, unbleached kraft paper having high strength is used, but conversely, unbleached kraft paper cannot have a high bulkiness. As measures for improving the bulkiness of the wrapping paper, high blending of mechanical pulp that is rigid and easily creates voids between fibers, and the use of bulking agents are being studied. However, the blending of the mechanical pulp has the disadvantage of reducing the paper strength as kraft paper, although it is possible to obtain bulkiness at low cost. In addition, the bulking agent is expensive and has the property of hindering or separating the bonding between fibers, and therefore has the disadvantage of reducing not only the surface strength but also the paper quality strength in the Z-axis (thickness) direction. .

  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 in JIS-P4301 (2000), the original rank can be achieved even if the basis weight under one standard is reduced. It does not satisfy the strength.

  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 simply provides coating-type kraft paper that satisfies the three craft standards with the same basis weight and has printability and bag-making suitability. Can not do it.

  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. It is disclosed.

  However, the low-density paper disclosed in Patent Document 3 satisfies the quality as printing paper for books and paperbacks, and does not have sufficient processability and strength as packaging paper for bag making. There is no disclosure of a technical idea that can solve the problem of improvement in property and strength.

  Furthermore, Patent Document 4 contains 10-50% by mass of pulverized pulp having an average fiber length of 0.5 mm or less by mechanically pulverizing after drying coniferous chemical pulp to a moisture content of 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 for printing paper, recording paper, and base paper for coating, but does not have processability and strength as packaging paper for bag making. .

  In a wrapping paper for bag making that requires high strength, soft pulp unbleached pulp having high strength is used as a main raw material as a pulp raw material. However, the invention of kraft paper using softwood unbleached pulp that provides weight reduction and bulkiness while maintaining high strength and satisfies processing suitability as a packaging paper for bag making has not yet been achieved.

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-mentioned background art, and provides a kraft paper made mainly of unbleached pulp of conifers, which is bulky and has processing suitability and strength as packaging paper for bag making. For the purpose.

The invention made to solve the above problems is
In kraft paper made mainly from unbleached kraft pulp,
Contains an ester compound of a fatty acid and a polyhydric alcohol,
Water-soluble resin is coated on one side,
The freeness is 550 cc CSF or more and 700 cc CSF or less, and the density is 0.4 g / cm ³ or more and 0.6 g / cm ³ or less,
Contains regenerated particles made mainly from deinked floss discharged from the waste paper processing process as a filler,
The regenerated particles dehydrate the deinking floss, the first combustion in which the deinking floss after the dehydration is dried and burned in series in the furnace, the second combustion in which the combustion product of the first combustion is burned again in the furnace. Obtained through combustion and comminution of the combustion product of this second combustion,
The furnace temperature of the first combustion is 300 ° C. or more and 500 ° C. or less,
The kraft paper is characterized in that the oxygen concentration of hot air blown into the first combustion furnace is 0.2% or more and 20% or less.

  According to the craft paper, bulkiness can be imparted by containing an ester compound of a fatty acid and a polyhydric alcohol. Moreover, the said kraft paper can prevent the fall of the intensity | strength which may arise by becoming bulky by coating the surface with water-soluble resin. Furthermore, the kraft paper contains an ester compound, and has a processing suitability suitable as a packaging paper for bag-making because the surface is coated with a water-soluble resin.

  The ester compound may have an HLB value of 3 or more and 11 or less. The HLB value is a measure of the hydrophilicity of the surfactant, and ester compounds having an HLB value in this range weaken hydrogen bonds between pulp fibers due to their moderate hydrophobicity and increase the bulkiness of the ester compound. A part of the lignin remaining in a relatively large amount can be dissolved. In addition, since the water-soluble resin applied to the surface has solubility due to the presence of an appropriate hydrophilic group, both the bulkiness, strength and processability of the kraft paper can be improved.

  The weight average fiber length of the kraft pulp disaggregated by a method according to JIS-P8220 (1998) is 2 mm to 3.5 mm, and the average runkel ratio of the kraft pulp is 0.9 to 1.1. Is preferred. According to the kraft paper in which the mass average fiber length and the average Runkel ratio of the kraft pulp are within the above ranges, the bulk and strength can be maintained, and appropriate stiffness can be provided as the kraft paper.

  The copper number measured according to JIS-P8211 (1998) of the kraft pulp is 50 or more and 70 or less, and the brightness measured according to JIS-P8150 (2004) of the kraft pulp is 54 or more and 60 or less. Is preferred. By making the copper value and lightness of the pulp within the above ranges, the strength and processing suitability of the kraft paper can be further increased.

  The kraft paper contains recycled particles having a whiteness of 75% or more and 85% or less obtained from the deinking floss discharged from the used paper processing process as a filler, and the ash content measured according to JIS-P8251 (2003). Is preferably 0.5% by mass or more and 3.0% by mass or less. According to the kraft paper, by containing such regenerated particles so that the ash content falls within the above range, the bulkiness can be further improved and high opacity can be realized while maintaining processing suitability.

  In addition, the freeness in this invention means the freeness measured with the Canadian standard freeness tester based on JIS-P8121 (1995) of the kraft pulp disaggregated by the method based on JIS-P8220 (1998). . Further, the density refers to the mass per unit volume calculated from the basis weight of paper measured according to JIS-P8118 (1998) and the thickness of a single sheet.

  According to the present invention, kraft paper that is optimal for bag-making packaging paper that is made of softwood unbleached pulp and that is bulky, has processing suitability and strength as bag-making packaging paper, and can be reduced in weight. Can be provided.

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

  Hereinafter, the kraft paper of the present invention will be described in detail.

  The kraft paper of the present invention contains softwood unbleached kraft pulp (NUKP) as a main raw material and an ester compound of a fatty acid and a polyhydric alcohol, and a water-soluble resin is coated on the surface.

〔pulp〕
In addition to the softwood unbleached kraft pulp (NUKP) as the main raw material, the raw material of the pulp in the present invention includes, for example, hardwood unbleached kraft pulp (LUKP), hardwood semi-bleached kraft pulp (LSBKP), softwood semi-bleached kraft pulp ( NSBKP), chemical pulp such as hardwood sulfite pulp, coniferous sulfite pulp, stone grand pulp (SGP), pressed stone grand pulp (PGW), refiner grand pulp (RGP), thermo grand pulp (TGP), chemi grand pulp (CGP) ), Mechanical pulp such as groundwood pulp (GP) and thermomechanical pulp (TMP). In the present invention, the main raw material pulp means occupying 50% by mass or more of the total pulp raw material.

  As the softwood unbleached kraft pulp (NUKP) as the main raw material, a kappa value adjusted to 50 to 70, more preferably 55 to 65 is preferable. Generally, the kappa number of commercially available softwood unbleached kraft pulp (NUKP) is adjusted to 20-40. 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 unbleached kraft pulp used in the present invention is preferably 54 to 60. When the lightness is less than 54, the wood-derived resin content and lignin tend to decrease, the opacity tends to decrease, and the strength decreases. On the other hand, when the lightness exceeds 60, the amount of resin derived from wood and the residual amount of lignin tend to be large, tend to cause stains on the processing machine at the time of bag making, and the bulkiness decreases due to the influence of lignin. Further, since there is a tendency to discolor due to light, it is difficult to stabilize the color tone as a product.

  In the present invention, paper is made by blending the above-described unbleached kraft pulp (NUKP) as a main raw material pulp. At that time, the freeness measured according to JIS-P8121 (1995) of disaggregated pulp disaggregated by the method according to JIS-P8220 (1998) of the kraft paper of the present invention is 550 to 700 ccCSF, preferably 600 to 650 ccCSF. There should be. When the disaggregation freeness is less than 550 cc CSF, the fiber length of the pulp is shortened, and the fiber diameter of the pulp itself is thinned. Therefore, the rigidity cannot be maintained as kraft paper for bag making, and the tear strength is reduced. Cannot achieve the goal. Further, when the disaggregation freeness exceeds 700 cc CSF, the fiber length of the pulp is increased and the fiber diameter of the pulp is increased, so that the tensile strength necessary for 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 the kraft paper, it is preferable to adjust 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 obtained from the width (diameter) L of the lumen of the fiber and the thickness t of the cell wall, and is represented by R = 2 · t / L. 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. .

  A more preferable kraft paper can be obtained by performing the selection, classification, and beating of the above-mentioned raw pulp at a minimum 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. Classifying means using a thickener, screen, cleaner, etc., and other well-known SP filters, washers, extractors, filter presses, etc., which are generally used in paper and pulp factories. It means to classify while diluting. Beating means beating with a conical refiner, cylindrical refiner, disc refiner, or the like.

  In the said kraft paper, it is preferable that the mass mean fiber length of the disaggregated pulp disaggregated based on JIS-P8220 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 mass 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 mass average fiber length of the disaggregated pulp exceeds 3.5 mm, because of the long fibers, the entanglement between the pulp fibers increases, resulting in uneven formation, and the appearance as a wrapping paper is deteriorated and the paper stiffness is reduced. Is insufficient. Further, by setting the mass average fiber length to 2.2 mm or more and less than 3.0 mm, it is possible to secure paper strength and density that can effectively achieve the object of the present invention.

  The weight average fiber length referred to in the present invention is a value of a weight average fiber length measured using a fiber length measuring machine fiber lab manufactured by Kayani Automation Co., Ltd. for disaggregated pulp after disaggregation according to JIS-P8220. 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 pulp of this form, various additives usually added to kraft paper such as sizing agent, paper strength enhancer, paper thickness improver, yield improver, etc. Can be used.

[Ester compound]
The kraft paper contains an ester compound of a fatty acid and a polyhydric alcohol as a bulking agent. Conventionally, a method of adding a bulking agent to the raw pulp slurry and improving the bulkiness of the resulting printing paper has been tried, but the bulking agent reduces the paper quality strength mainly by the Z-axis strength of the paper. In paper, its use was refrained. In the present invention, the object of the present invention can be achieved more effectively by selecting the specified bulking agent and combining it with a specific water-soluble resin. Since the bulking agent contained in the kraft paper is an ester compound of a fatty acid and a polyhydric alcohol, it has a hydrophilic group and a hydrophobic group. Therefore, since the bulking agent has compatibility with the lignin resin that maintains the strength of the pulp fiber, the water-soluble resin applied to the surface, and the lignin resin remaining in the pulp, the adhesion between the lignin resin and the water-soluble resin and ester Thus, it is possible to prevent deterioration of the paper quality of the paper and to exhibit excellent processing suitability and strength while maintaining the bulkiness.

  In particular, the relationship between the HLB value and the paper strength is preferably a causal relationship in the case of softwood unbleached pulp. This is considered to be related to the amount of lignin remaining in unbleached softwood pulp. That is, the unbleached pulp in which a large amount of lignin remains in comparison with other pulps is strong, but the bulk is low, and when a normal bulking agent is added, the strength of the pulp is reduced. There is an inconvenience of doing. It is thought that this is because the bulkiness is increased and the strength is weakened by mixing the bulking agent between pulp fibers and lignin resin. On the other hand, according to the inclusion of an ester having an HLB value within a predetermined range, the strength does not decrease because the ester is compatible with the lignin resin and adheres closely to the lignin resin. It is done.

  The fatty acid constituting the ester compound of the present invention includes a fatty acid having 1 to 24 carbon atoms, preferably 10 to 22 carbon atoms, particularly preferably 16 to 22 carbon atoms, saturated, unsaturated, linear, branched chain. Either is acceptable. From the standpoint that the bulkiness effect is large and does not affect the size, linear saturated fatty acids are particularly preferable. Preferred fatty acids are lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid and arachidic acid, and myristic acid, palmitic acid, stearic acid, behenic acid and arachidic acid are particularly preferred.

  The polyhydric alcohol constituting the ester compound of the present invention is preferably a 2-14 valent alcohol having 2-24 total carbon atoms which may contain an ether group. Examples of the dihydric alcohol include those having a total carbon number of 2 to 10 which may contain an ether group, such as propylene glycol, dipropylene glycol, butylene glycol, dibutylene glycol, ethylene glycol, diethylene glycol, and polyethylene glycol. . The trivalent or higher valent alcohol is an alcohol having a total carbon number of 3 to 24 which may have an ether group, for example, glycerin, poly (n = 2 to 5) glycerin, pentaerythritol, dipentaerythritol, arabitol, sorbitol. , Stachyose, erythritol, arabit, mannitol, glucose, sucrose and the like. Glycerin, poly (n = 2 to 4) glycerin, pentaerythritol, and the like are preferable from the viewpoint of a large bulky effect and availability.

  The ester compound of the present invention can be obtained by performing a conventionally known esterification reaction. For example, it can be obtained by reacting a fatty acid and a polyhydric alcohol at 150 to 250 ° C. in the presence of an esterification catalyst.

  The HLB value of the ester compound of the present invention is preferably 3 or more and 11 or less, and particularly preferably 3 or more and 8 or less. The HLB value is a measure of the hydrophilicity of the surfactant. The higher the value, the higher the hydrophilicity. If the HLB value of the ester compound is less than the above range, the hydrophilicity is too low, the solubility with the water-soluble resin applied to the surface becomes low, and the action of coating the surface of the water-soluble resin becomes weak, so the strength Decreases. On the other hand, when the HLB value of the ester compound exceeds the above range, the hydrophilicity is increased and the solubility in the water-soluble resin is increased, but the force to weaken the hydrogen bond between the pulp fibers is weak and the bulkiness is not increased. The kraft paper contains an ester compound having such an HLB value, thereby improving the affinity with the water-soluble resin coated on the surface while weakening the inter-fiber strength in the pulp fiber. Therefore, the strength of the kraft paper can be increased while maintaining the bulkiness.

  In the present invention, the HLB value of each compound is calculated by the following formula according to the method of glyphein.

HLB = (molecular weight of hydrophilic group portion / molecular weight of ester compound) × 20
However, in the present invention, the hydrophilic group means the following group in the ester compound.
(1)-(CH ₂ CH ₂ O)-
(2)-(AO) _n-
[A: an alkylene group having 3 to 4 carbon atoms,
n <2.0 (where n is the total number of moles of AO added in one molecule)]
(3) Alcohol having 3 to 24 total carbon atoms which may have an ether group, and an alcohol and a fatty acid having a total hydroxyl number / total carbon number in a molecule of 0.4 to 1 The oxygen atom adjacent to the acyl group of the ester compound and the remaining (4) carbonyl group excluding the n ≧ 2 part in (2) above

  As content of the said ester compound, 0.4-3.0 mass% is preferable with respect to pulp solid content, and 0.5-1.8 mass% is especially preferable. If the content is less than the above range, sufficient bulkiness cannot be obtained, while if it exceeds the above range, hydrogen bonds between pulp fibers are excessively decreased, and the strength of the kraft paper is decreased.

(Water-soluble resin)
Furthermore, in the present invention, by applying a water-soluble resin to one or both sides, preferably both sides of the base paper, it compensates for paper stiffness and strength deterioration accompanying mechanical pulp blending, etc., and more effectively the craft of the present invention. Paper can be achieved.

  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 a mixture of two or more. 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. If the coating amount is less than the above, sufficient strength cannot be obtained. On the other hand, when the coating amount exceeds the above range, the processing suitability decreases although the strength is sufficient.

Kraft paper of the invention is preferably a basis weight of 50 to 120 / ^{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 mass of paper per square meter and may vary depending on the thickness and density of the paper.

  In particular, when packaging paper for bag making in recent years is inferior to the conventional hand feeling in response to the need for products that are more resource-saving and environmentally friendly, it has been promoted to reduce the weight to a standard size of US tsubo. Is starting to be seen.

Therefore, although there is a tendency to reduce weight while sacrificing hand feeling, in the present invention, a bag making packaging having a basis weight of 50 to 120 g / m ^{2 that} can be suitably adapted to a known bag making machine as a bag making packaging paper. In the 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 above raw material pulp, if necessary, various fillers, internally added sizing agents, fixing agents, yield improvers, cationizing agents, paper strength enhancing agents, and the like. 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.

[Filler]
Examples of the filler contained in the kraft paper include regenerated particles, light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, satin white, and silicic acid. White inorganic pigments such as aluminum, diatomaceous earth, calcium silicate, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide; styrene plastic pigment, acrylic plastic pigment, polyethylene, Examples thereof include organic pigments such as microcapsules, urea resins, and melamine resins. Among these, regenerated particles are preferable from the viewpoint of bulkiness effect and improvement of surface strength.

  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 processes 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.

  An example of the method for producing regenerated particles according to the present invention will be described below with reference to FIGS.

  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 and precooled by the precooler 24, then passes through the heat exchanger 26, and is 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.

  The outline of the production process of regenerated particles has been described above, and details and application examples thereof will be described 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.

  The raw material 10 after such dehydration has an average particle diameter of preferably 40 mm or less, more preferably 3 mm to 30 mm, most preferably 5 mm to 20 mm by a pulverizer (or pulverizer) in the operation of supplying the raw material 10 to the first combustion furnace 14. It is adjusted to become. Furthermore, it is more preferable to grind so that the ratio of an average particle diameter of 50 mm or less may be 70 mass% 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 oxygen concentration of the hot air blown into the first combustion furnace 14 is preferably 0.2% to 20%, more preferably 1% to 17%, and most preferably 7% to 15%. .

  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 is preferably burned 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. Moreover, 40 minutes-80 minutes are more preferable in terms of the combustion of organic matter and production efficiency, and 50 minutes-70 minutes are the most preferable from the aspect 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 residual organic matter, particularly residual carbon, that could not be burned in the first combustion furnace 14, and therefore burns at a higher temperature than the first combustion furnace 14. Preferably, if the combustion temperature is less than 550 ° C., it is difficult to sufficiently burn the residual organic matter, and if the combustion temperature exceeds 780 ° C., the oxidation of calcium carbonate in the combustion product proceeds and the particles The problem of stiffening 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 products 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 thermothermal mass measurement apparatus. 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. A plurality of helical lifters 32d inclined at an inclination angle of 45 ° to 70 ° with respect to the axial center of the cylindrical main body 32b are attached to the inner surface of the fireproof wall 32c on the input portion 32a side of the cylindrical main body 32b. The other end side is provided with a plurality of parallel lifters 32f of appropriate length parallel to the axis of the cylindrical main body 32b at equal intervals in the circumferential direction. It protrudes in the direction through a plurality of rows of brackets 32g.

  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 packaging paper for bag making, the paper strength is reduced as compared with the case of using conventionally known regenerated particles and calcium carbonate which is a commercially available filler. A wrapping paper that is small and bulky and can be used as a kraft paper for bag making can be obtained.

  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 wrapping paper with less decrease in paper strength is provided. can do.

  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 the present embodiment, the regenerated particles can be used alone as described above, and as such regenerated particles and a filler for internal addition, normally used heavy calcium carbonate, light calcium carbonate, talc, clay, kaolin In addition, at least one filler selected from inorganic fillers such as titanium dioxide, 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.

  As the content of regenerated particles, the ash content of the kraft paper measured according to JIS-P8251 (2003) is 0.4 to 3.0% by mass, preferably 0.5 to 3.0% by mass, more preferably It is desirable to contain so that it may become 0.5-1.8 mass%. When the ash content exceeds 3.0% by mass, it is difficult to obtain a packaging paper for bag making that is bulky and has excellent processability and strength as a bag making application. On the other hand, when the ash content is less than 0.5% by mass, the degree of whiteness may decrease and the processability may decrease.

  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, when applying the kraft paper according to the present embodiment to, for example, offset printing in particular, since fountain solution is used in the offset printing, the kraft paper of the present invention is appropriately given sizing (water absorption resistance). It is preferable to do. 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, the internal sizing agent as described above is added to the raw material pulp slurry, and the internal sizing agent is contained in the kraft paper of the present invention at the same time as the paper making, or after the paper making, the two rolls It is preferable to apply a surface sizing agent to the surface of the kraft 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, in the case of using the above internally added sizing agent, 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, Furthermore, it is 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 further improve the moisture resistance and water resistance, the coating amount on the wrapping paper of the present invention can be 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 kraft paper of the present invention according to the present embodiment, measured according to “Test method of thickness and density” described in JIS-P8118, is 0.4 to 0.6 g / cm ³ , but this is required. The density is necessary in combination with the printability. When the density is out of the above range, the printability is lowered. Stiffness (vertical) measured in accordance with “Paper Clark Stiffness Test Method” described in JIS-P8143 gives good printing workability and feel and maintains sufficient printability. terms, is preferably about 70~180cm ^3/100.

  As described above, the kraft paper according to the present embodiment is strong and strong in workability and printability despite being lightweight 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.

Example 1
The pulp slurry of softwood unbleached kraft pulp adjusted so that the disaggregated pulp freeness after disaggregation becomes CSF 550 cc, 1.6% by mass as a solid content of a chemical mainly composed of an ester compound of a fatty acid and a polyhydric alcohol, Aluminum sulfate (sulfuric acid band, manufactured by Showa Chemical Industry Co., Ltd.) is 0.28% by mass in solid content, and neutral rosin sizing agent (product number: NS74, manufactured by Harima Chemicals Co., Ltd.) is 0.1 mass in solid content. % And a paper strength enhancer (product number: Amilofax TS2600, manufactured by AVEBEb.a.) Are added in an amount of 0.5% by mass as a solid content, and a filler shown in Table 2 is added, and then a wire part and a press part are added. Paper making system including pre-dryer part, size part, after-dryer part, calendar part, reel part and winder part Paper.

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, Japanese food processing) on one side with a gate roll coater. The kraft paper of Example 1 was obtained by coating so that the solid content was 0.8 g / m ² .

  The freeness, fiber length, and Runkel ratio were adjusted using a commercially available disintegrator, beater, and the like. The ash content was adjusted by changing the amount of regenerated particles added.

(Examples 2-49)
Kraft papers of Examples 2 to 49 were obtained in the same manner as in Example 1 except that the conditions described in Table 1 were used for each pulp and additives.

In addition, in the kind of ester etc. of Table 1, the following was used (the numerical value in a parenthesis is an HLB value).
A: Propylene glycol sesquill palmitate (2.4),
B: sorbitol trilaurate (3.1),
C: stearic acid monoglyceride (3.8),
D: Diglycerin monomyristate (5.9),
E: Sorbitan monomyristate (7.6),
F: Saccharose monooleate (10.8),
G: sorbitan monolaurate EO average 6 mol adduct (13.3)
H: Water-soluble urethane resin bulking agent (non-ester compound)
I: Fatty acid polyamidoamine bulking agent (non-ester compound)

Moreover, tapioca starch which used the following as water-soluble resin in each Example: SB GUM-EVOSB gum, Sanki Co., Ltd. PVA: JF-04, Japanese vinegar Bipoval Co., Ltd. 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.

  The internally added filler uses deinking floss (deinking floss obtained from the used paper processing process for producing used paper pulp) as a raw material, and the dehydration process and the first combustion process (drying / combustion) under the conditions shown in Table 2 Step) After the second combustion step, wet pulverization was performed to obtain regenerated particles as a filler.

(Comparative example)
As a comparative example, kraft paper according to comparative examples 1 and 2 was obtained under the conditions shown in Table 1. Other conditions not shown in the table are the same as in the examples.

  The evaluation results are shown in Table 3. The measurement method is as follows.

(Copper value)
Measured according to JIS-P8211 (1998) “Pulp-Kappa number test method”.

(brightness)
L (brightness) value measured with a spectral white photometer “SC-10WT” (manufactured by Suga Test Instruments Co., Ltd.)

(Freeness)
The freeness of the disaggregated pulp disaggregated by the method according to JIS-P8220 (1998) “pulp-disaggregation method” is a Canadian standard filter according to the method described in JIS-P8121 (1995) “pulp freeness test method”. Freeness value of disaggregated pulp measured with a water tester.

(Weight average fiber length)
The obtained test paper was disaggregated by a method based on JIS-P8220 (1998). TAPPI NO. 52, the value of the weight average fiber length 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.

(density)
It measured based on JIS-P8118 (1998).

(Specific tensile strength)
It measured based on JIS-P8113.

(Specific 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.

(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.
×: In the processed square bottom bag, the frequency of occurrence of square cracks is more than double that of conventional unbleached kraft paper

  From the results shown in Table 3, the kraft papers of Examples 1 to 49 satisfy specific values for density, specific tensile strength, and specific tear, and have high bulkiness, strength, and appropriate bag making. You can see that it is equipped.

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 (5)

In kraft paper made mainly from unbleached kraft pulp,
Contains an ester compound of a fatty acid and a polyhydric alcohol,
Water-soluble resin is coated on one side,
The freeness is 550 cc CSF or more and 700 cc CSF or less, and the density is 0.4 g / cm ³ or more and 0.6 g / cm ³ or less,
Contains regenerated particles made mainly from deinked floss discharged from the waste paper processing process as a filler,
The regenerated particles dehydrate the deinking floss, the first combustion in which the deinking floss after the dehydration is dried and burned in series in the furnace, the second combustion in which the combustion product of the first combustion is burned again in the furnace. Obtained through combustion and comminution of the combustion product of this second combustion,
The furnace temperature of the first combustion Ri der 300 ° C. or higher 500 ° C. or less,
Kraft paper, wherein the oxygen concentration of hot air blown into the first combustion furnace is 0.2% or more and 20% or less .   The kraft paper according to claim 1, wherein the ester compound has an HLB value of 3 or more and 11 or less.   The kraft paper according to claim 1 or 2, wherein the kraft pulp has a weight average fiber length of 2 mm to 3.5 mm and an average Runkel ratio of 0.9 to 1.1.   The kraft paper according to claim 1, 2 or 3, wherein the kraft pulp has a copper number of 50 or more and 70 or less and a lightness of 54 or more and 60 or less. The whiteness of the regenerated particles is 75% or more and 85% or less,
The kraft paper according to any one of claims 1 to 4, wherein an ash content is 0.5 mass% or more and 3 mass% or less.

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