JP2006328572A - Paperboard - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce wastes by processing PS ash (incinerated ash of paper sludge) or coal ash by a relatively easy method and usefully using the ash in relation to a paperboard. <P>SOLUTION: The PS ash or coal ash is prepared so as to provide 20-100 μm average particle diameter. Thereby, the paperboard comprising the resultant ash mixed in an amount of ≥0.01 to ≤3 wt.% is produced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to paperboard, and more particularly, to a method for manufacturing paperboard by adding paper sludge incineration ash and coal ash.

  Among paper, it is known that cardboard used for corrugated cardboard cores, when forming a step in the production of cardboard sheets, will cause defective products such as step breakage and step breakage if there is no bulkiness. Yes. Therefore, a manufacturing method is used in which the density is lowered while maintaining the strength as much as possible. In addition, among papers, in particular, base papers such as paper tube base paper and paperboard base paper are traded on the basis of thickness, and therefore, more pulp than the indicated basis weight may be used. Therefore, it is required to be bulky while maintaining the strength. Therefore, an operation of increasing the bulk by adding a bulking agent to a high density paperboard raw material is performed. As the bulking agent, in addition to diatomaceous earth and silica powder, for example, as disclosed in Patent Document 1, a dedicated bulking agent may be synthesized and used for purposes.

  On the other hand, when manufacturing paper, various coating agents that were on the surface of the waste paper used as raw materials, plastics in the waste paper, fine fibers that were not used, and difficult-to-disintegrate fibers are discarded. Arises as This waste is called paper sludge. Since this paper sludge generates a huge amount during paper production, it cannot be processed by simply reclaiming it as it is, but is processed after it has been incinerated to form ash. Since the physical properties are not constant, there is not much useful use, and only a part is used as a raw material for cement, and most of it is treated as industrial waste.

  A method of effectively using such paper sludge has been studied. For example, Patent Document 2 discloses a method of using paper sludge as a white pigment for paper by treating the paper sludge at a high temperature.

JP 2005-89953 A JP 2001-26727 A

  However, the effect of diatomaceous earth and silica powder as a bulking agent is not sufficient, and if a bulking agent is made as in Patent Document 1, it takes too much time as a process to simply bulk the paper. It was too much, and the merit exceeding the drug cost was not obtained in the paperboard with a low unit price.

  On the other hand, when trying to use paper sludge incineration ash as a white pigment by the method of Patent Document 2, it is difficult to maintain the whiteness due to a large amount of impurities from the beginning, and processing work to use as a white pigment after incineration is difficult. was difficult.

  In addition, the residual ash of coal burned as fuel in paper mills, like paper sludge incineration ash, has few effective methods of use and must be handled as industrial waste. there were.

  Therefore, an object of the present invention is to process paper sludge incineration ash, coal ash, and the like by a relatively easy method and use them effectively to reduce waste.

  This invention produces the paperboard containing 0.01 wt% or more and 3 wt% or less of ash whose paper sludge incineration ash and coal ash have an average particle size of 20 to 100 µm with respect to the pulp raw material. The problem has been solved.

  Paper sludge incineration ash and coal ash are likely to become bulky due to heat during combustion, and thus have an efficient structure as an additive for making them bulky.

  In addition, it is possible to effectively use it without the labor conventionally required for processing as industrial waste. Furthermore, since it is added to the paperboard, it is not necessary to maintain the whiteness. In other words, in the case of a corrugated cardboard core, it does not appear on the surface even if the paper is colored by addition, but in the case of a liner, the color of the surface may be a problem. Since it has a structure, the problem can be avoided by adding ash only when making paper other than the surface layer where the color is a problem.

Hereinafter, the present invention will be described in detail.
The present invention is a paperboard containing ash having an average particle size of 20 μm or more and 100 μm or less, consisting of paper sludge incineration ash (hereinafter abbreviated as “PS ash”), coal ash, or both.

  The above PS ash is the various coating agents that were on the surface of the waste paper discharged outside the system in the raw material process, plastics in the waste paper, refractory fibers, and fine fibers that were not used in the paper making process Paper sludge, which is waste such as min, is incinerated, and its components are not particularly limited. Moreover, said coal ash is the ash which remains after burning coal, Although it does not specifically limit a component, it produced | generated from the coal burned for supply of the heat | fever required in a papermaking process Use of coal ash in the present invention is preferable because waste discharged from the entire process can be reduced. Furthermore, as said ash, not only these PS ash and coal ash but the ash produced in another process may be included partially.

The ash needs to have an average particle size of 20 μm or more, and more preferably 35 μm or more. When the average particle size is less than 20 μm, the individual particles are too small, and the effect of increasing the bulkiness of the paperboard is not sufficiently exhibited, and it is difficult to stay in the paper during the production of the paper. On the other hand, the average particle size is preferably 100 μm or less, and more preferably 70 μm or less. Since the thickness of the core having a basis weight of 120 g / m ² that is generally used is about 200 μm, it is problematic to add ash having a particle size larger than this. That is, when the average particle size exceeds 100 μm, the ash having a large particle size exceeding 200 μm increases, and as a result, the amount of ash penetrating the manufactured paperboard increases, which causes a problem such as opening a hole in the paperboard. In addition to being likely to occur, there is a possibility that the strength is too low. In addition, the average particle diameter in this invention means the particle diameter by arithmetic mean.

The ash preferably has a bulk density of 0.10 g / cm ³ or more, and more preferably 0.30 g / cm ³ or more. If it is less than 0.10 g / cm ³ , the density is too low, so that it tends to float in water and is difficult to disperse in water. On the other hand, the bulk density is preferably 1.00 g / cm ³ or less, and more preferably 0.70 g / cm ³ or less. This is because if the density exceeds 1.00 g / cm ³ , the density of the added paper increases and the bulkiness effect is not exhibited.

  When the above PS ash and coal ash obtained in the papermaking process do not satisfy the above average particle size and bulkiness conditions, it is generally that the particle size is large and the bulk density is high. Many. In such a case, the ash mass is crushed and classified to obtain an ash that satisfies the numerical ranges of the above average particle diameter and bulk density and used in the present invention. The crushing method is not particularly limited, and a general particle crushing method can be used. For example, a crushing machine using a centrifugal ball mill, a roll crusher, a roll mill, a stamp mill, an edge runner can be used. , Cutter mill, rod mill and the like.

  The paperboard according to the present invention is a paperboard containing 0.01% by weight or more and 3% by weight or less of the above ash. This paperboard has a higher bulk than that containing no ash.

  Examples of a method for adding the ash to the paperboard according to the present invention include a method for producing a paperboard by mixing the ash with a pulp raw material used in the papermaking process of the paperboard, or a plurality of paper layers between paper layers. Examples include a method of applying the ash and laminating. Moreover, the method of using both of these methods together may be used.

  First, a method for mixing the ash with a pulp raw material will be described. The mixing ratio when mixing the ash with the pulp raw material needs to be 0.01% by weight or more with respect to the pulp raw material, and is preferably 0.1% by weight or more. If it is less than 0.01% by weight, the effect of increasing the bulk is hardly exhibited, and the effect of reducing waste by adding ash is almost lost. On the other hand, it is required to be 10% by weight or less, and more preferably 3% by weight or less. If it exceeds 10% by weight, the strength of the produced paperboard may be too low, and if the ash increases, the paperboard cannot be produced in the first place. It is preferable that the amount of ash contained in the actually obtained paperboard does not exceed 3% by weight. However, when adding ash only to the middle layer in the case of multiple papermaking, the ash is 10% in the middle layer papermaking. %, The ash content in the entire paperboard can be reduced to 3% by weight or less by overlapping the surface layer and the back layer not containing ash. Further, when all of the single layer or multiple layers contain ash, the ash content in the paperboard raw material is preferably 3% by weight or less.

  In particular, a paperboard such as a liner, a paper tube base paper, and a chip ball is manufactured by combining two or more layers of paper. If ash is added to a single-layer paper such as a core, the ash may fall off from the product. However, if ash is added to the middle layer of multi-layer paper, it is covered by the front and back layers. In addition, ash can be prevented from falling off. In addition, liners and chip balls cause problems when the surface color is changed by ash, but by adding ash to the middle layer, there is no problem with coloring by ash.

  Thus, the paperboard manufactured using the paperboard raw material obtained by mixing the said ash with a pulp raw material can be manufactured by the procedure similar to the manufacturing process of a normal paperboard. The timing for adding the ash may be added to the material in a slurry state during papermaking, or may be added as an additive for the pulp itself, and the timing is not particularly limited.

  Next, a method for coating and stacking the above ash between a plurality of paper layers made of paper will be described. The method of applying the ash is not particularly limited as long as the ash can be added to the surface. For example, the ash is directly sprayed and sprayed with wind pressure, so that it becomes nearly uniform. And a method of applying, dipping and spraying the solution, colloid or mixed solution containing the ash.

The amount of the ash applied between the layers needs to occupy an amount in which the ash is 0.01% by weight or more and 3% by weight or less in the paperboard obtained by laminating. If it is less than 0.01% by weight, the bulking effect is not sufficient, and if it exceeds 3% by weight, there may be a problem in the strength of the paperboard. This value is not only established by coating only on one surface, but may be obtained by coating between a plurality of layers. In some cases, the ash is dispersed and it is easier to stack the layers when the coating is performed between a plurality of layers than when the coating is performed between only one layer. However, the coating amount of the ash between the respective layers is preferably 0.01 g / m ² or more, and more preferably 0.1 g / m ² or more, from the efficiency of actual coating. On the other hand, preferable to be 10 g / ^{m 2} or less, more preferably 5 g / ^{m 2} or less.

  The paperboard according to the present invention has a specific compressive strength of preferably 90% or more, and more preferably 95% or more, as compared to a paperboard obtained under the same conditions except that the ash is not added. This is because if the specific compressive strength is lowered to below 90%, there is a possibility that a problem may occur in use as a paperboard. On the other hand, it is unlikely that the specific compressive strength of the paperboard to which the ash is added is higher than the specific compressive strength of the paperboard to which no ash is added.

  The paperboard produced using the paperboard raw material according to the present invention preferably has a breaking length of 90% or more as compared with the paperboard obtained under the same conditions except that the above ash is not added. % Or more is more preferable. This is because if the tearing length is reduced to be less than 90%, there is a possibility that a problem may occur in use as a paperboard. On the other hand, it is unlikely that the breaking length of the paperboard to which the ash is added is higher than the breaking length of the paperboard to which no ash is added.

  The paperboard produced using the paperboard raw material according to the present invention preferably has a density of 99% or less with respect to the paperboard produced without adding the ash, and more preferably 98% or less. preferable. This is because even if the ash is added, if the density exceeds 99%, the effect of increasing the bulkiness is insufficient. On the other hand, it is not realistic that the density falls below 80%.

  Specific examples of use of the paperboard produced using the paperboard raw material according to the present invention include gypsum board paper, base paper for mount, base paper for paper containers, base paper for paper tube, and base paper for cardboard. Among these, in particular, when used as the corrugated cardboard as the base paper for corrugated cardboard, the balance between bulkiness and strength is suitable, which is preferable.

  By using this invention, PS ash and coal ash, which have been often discarded in the past, can be effectively used as an additive material for paper, waste can be reduced, and resources can be effectively utilized. Further, even if the obtained paperboard is bulky, it has a relatively small decrease in strength and is useful. Furthermore, since it is used for paperboard, there are few demerits by coloring with the component contained in ash, and since it is not necessary to thoroughly whiten the ash, processing of ash can be performed easily. However, when coloring with ash is excessive, a general white pigment may be added in order to ensure a certain degree of whiteness when the paperboard raw material is manufactured.

  Hereinafter, the present invention will be described more specifically with reference to examples.

<Measurement of particle size effect>
(Examples 1-3, Comparative Examples 1-3)
PS ash obtained by incineration of paper sludge generated at Rengo Co., Ltd.'s Kanazu Plant using a rotary kiln with a hot air oven (manufactured by Tsukishima Kikai Co., Ltd.) is subjected to an experimental centrifugal ball mill (Fritsch Japan) after dehydration. To obtain an average particle size of 15 μm (Comparative Example 1), 36 μm (Example 1), 57 μm (Example 2), 96 μm (Example 3), and 144 μm (Comparative Example 2). did. The average particle size is measured using a laser diffraction / scattering particle size distribution measuring device (Horiba, Ltd .: LA-920), and the average particle size is an arithmetic average unless otherwise specified. Asked.

  In addition, for each ash, a predetermined weight of ash was placed in a graduated cylinder and filled with vibration, and the value of the bulk volume at that time was read, and the bulk density was calculated from the weight and bulk volume of the ash. The results are shown in Table 1.

JIS P 8222 (Method for preparing test paperboard) using a square test paper machine after adding 3% by weight of each prepared PS ash to pulp raw material (Rengo Co., Ltd., manufactured by Kanazu Factory: core paper stock) Based on the above, a handsheet was prepared so as to have a basis weight of around 200 g / m ² . Moreover, as Comparative Example 3, a handsheet having a basis weight of about 200 g / m ² without adding PS ash was prepared.

  Each prepared handsheet was conditioned, and the paper thickness, density, specific compressive strength, and tear length were measured by the following methods. The results are shown in Table 1. All measurements were performed in an environment of a temperature of 23 degrees and a humidity of 50% RH.

(Paper thickness measurement method)
Measured according to JIS P 8118 “Paper and paperboard—Test method for thickness and density”.

(Specific compression strength measurement method)
It was measured based on JIS P 8126 “Testing method for compressive strength of paperboard (ring crush method)”.

(Fracture length measurement method)
It was measured based on JIS P 8113 “Paper and paperboard—Test method for tensile properties”.

(result)
The handsheet of Comparative Example 1 in which the average particle size of the ash charged is 15 μm, although the paper thickness is slightly increased compared with the handsheet of Comparative Example 3 to which nothing is attached, the density value is almost the same. Yes, the effect of increasing the bulkiness was not sufficient.

  The handsheets into which ash having an average particle diameter of 36 μm, 57 μm, and 96 μm in Examples 1 to 3 is reduced in density and the paper thickness as compared with Comparative Example 3 in which no ash was added. The effect of increasing greatly and increasing the bulkiness appeared. Moreover, the decrease in specific compressive strength and tearing length was relatively small.

  The handsheet of Comparative Example 2 in which the average particle size of the ash charged was 144 μm was sufficiently lower in density and increased in paper thickness than Comparative Example 3, but the decrease in specific compressive strength exceeded 10%. Also, the decrease in tearing length is not negligible.

<Confirmation of effects at different sources>
Example 4
PS ash produced at Rengo Co., Ltd. Kanazu Office was pulverized in a mortar for 3 minutes and passed through a sieve having an opening of 250 μm to an average particle size of 100.0 μm. The particle size was measured in the same manner as in Example 1. Further, the bulk density was measured using a graduated cylinder in the same manner as in Example 1. After mixing 3% by weight of this ash with the pulp raw material, a handsheet was prepared with a square test paper machine so that the basis weight was around 200 g / m ² based on JIS P 8222 (method for preparing a test handsheet). . Table 2 shows values obtained by measuring the basis weight, paper thickness, and density of the handsheets obtained. Further, the specific compressive strength and tear length of this handsheet were measured. The results are shown in Table 2. All measurements were performed in an environment of a temperature of 23 ° C. and a humidity of 50% RH.

(Example 5)
The PS ash produced at Yenshi Office of Rengo Co., Ltd. was pulverized in a mortar for 3 minutes and passed through a sieve having an opening of 250 μm to give an average particle size of 94 μm. This ash was measured in the same manner as in Example 4, paper was made, and a handsheet was produced. The values measured in the same manner are shown in Table 2.

(Example 6)
PS ash produced at Rengo Co., Ltd. Amagasaki Office was pulverized in a mortar for 3 minutes, and passed through a sieve having an opening of 250 μm to obtain an average particle size of 72 μm. This ash was measured in the same manner as in Example 4, paper was made, and a handsheet was produced. The values measured in the same manner are shown in Table 2.

(Example 7)
Rengo Co., Ltd. Jinzu Office obtained fine powdered ash (average particle size 28 μm) collected by an electrostatic precipitator among coal ash (produced in China) used as fuel. This ash was measured in the same manner as in Example 4 and paper was made to prepare handsheets. The values measured in the same manner are shown in Table 2.

(Comparative Example 4)
In the procedure of Example 4, a handsheet was prepared by making paper so that the basis weight was about 200 g / m ² by the same procedure as in Example 4 except that ash was not added. The handsheet was measured according to the same procedure as in Example 4. The results are shown in Table 2.

(result)
The handsheets to which ash was added had a lower density than the handsheets to which no ash was added, and in particular, Examples 4 and 5 in which the particle size was close to 100 μm greatly reduced the density. Moreover, all the specific compressive strengths maintained essential strength. From these results, it was confirmed that the PS ash at the paperboard paper mill has a bulky effect without particularly having to stick to the firing conditions and the composition of the paper sludge.

<Effect of mixed ash of PS ash and coal ash>
(Example 8)
PS ash prepared by the same procedure as in Example 4 and coal ash of Example 7 were mixed at a weight ratio of 1: 1, and the mixed ash was mixed 3% by weight with respect to the pulp raw material. Handsheets were made according to the same procedure as in Example 4. The values measured in the same manner are shown in Table 2.

(result)
Compared with Comparative Example 4 in which no ash was added, the addition of mixed ash increased the paper thickness and reduced the density. Further, the decrease in specific compressive strength was 10% or less, and the essential strength was maintained. It was found that even the ash mixed with PS ash and coal ash exhibited a bulky effect and reduced the strength.

<Measurement of effects in the case of multi-layer papermaking>
Example 9
PS ash produced at Rengo Co., Ltd. Kanazu Office was pulverized in a mortar for 3 minutes and passed through a sieve having an opening of 250 μm to an average particle size of 100.0 μm. 6% by weight of this ash is mixed with the pulp raw material to produce a middle layer of a three-layer handsheet having a basis weight of about 100 g / m ² , and a basis weight of about 50 g / m ² by the pulp raw material not mixed with ash. The surface layer and the back layer of the three-layer handsheets were made and combined to produce a three-layer handsheet having a basis weight of about 200 g / m ² and containing 3% by weight of ash. Table 3 shows values obtained by measuring the basis weight, paper thickness, and density of the obtained three-layer handsheet. Further, the specific compressive strength and tear length of this three-layer handsheet were measured. The results are shown in Table 3. All measurements were performed in an environment of a temperature of 23 ° C. and a humidity of 50% RH.

(Example 10)
The PS ash produced at Yenshi Office of Rengo Co., Ltd. was pulverized in a mortar for 3 minutes and passed through a sieve having an opening of 250 μm to give an average particle size of 94 μm. This ash was mixed with a pulp raw material for producing the middle layer of a three-layer handsheet in the same manner as in Example 9 to prepare a three-layer handsheet. The values measured in the same manner are shown in Table 3.

(Example 11)
PS ash produced at Rengo Co., Ltd. Amagasaki Office was pulverized in a mortar for 3 minutes, and passed through a sieve having an opening of 250 μm to obtain an average particle size of 72 μm. This ash was mixed with a pulp raw material for producing the middle layer of a three-layer handsheet in the same manner as in Example 9 to prepare a three-layer handsheet. The values measured in the same manner are shown in Table 3.

(Example 12)
At Rengo Co., Ltd. Jinzu Office, coal ash (coal made in China) used as fuel was pulverized in a mortar for 3 minutes and passed through a sieve having a mesh size of 250 μm to an average particle size of 28 μm. This ash was mixed with a pulp raw material for producing the middle layer of a three-layer handsheet in the same manner as in Example 9 to prepare a three-layer handsheet. The values measured in the same manner are shown in Table 3.

(Comparative Example 5)
In the procedure of Example 9, a three-layer handsheet was prepared by the same procedure as in Example 9 except that ash was not added so that the basis weight was about 200 g / m ² . The blank three-layer handsheet was measured by the same procedure as in Example 9. The results are shown in Table 3.

(result)
The density of the three-layer handsheet with the ash added to the middle layer was lower than that of the three-layer handsheet without the ash added. In particular, Examples 9 to 11 having a large particle size greatly decreased the density. Moreover, all the specific compressive strengths maintained essential strength. Furthermore, the tearing length was less reduced than when ash was added to the core of the single layer, and the strength was maintained.

<Measurement of effect by amount added>
(Examples 13 and 14, Comparative Examples 6 and 7)
The PS ash (average particle size: 36 μm) used in Example 1 was 1.0% by weight (Example 13) and 3%, respectively, with respect to the pulp raw material (manufactured by Rengo Co., Ltd., Kanazu Factory: core raw material). 0.0 wt% (Example 14) and 5.0 wt% (Comparative Example 6) were added, and a basis weight of 200 g / g was measured with a square test paper machine based on JIS P 8222 (method for preparing handsheets for testing). m ² so that the front and rear, to prepare a handsheet. Further, as Comparative Example 7, a handsheet was prepared so as to have a basis weight of about 200 g / m ² without adding PS ash. These were measured in the same manner as in Example 1. The results are shown in Table 4.

(Examples 15 and 16, Comparative Examples 8 and 9)
The PS ash (average particle size: 96 μm) used in Example 3 was 1.0% by weight (Example 15) and 3%, respectively, with respect to pulp raw materials (manufactured by Rengo Co., Ltd., Kanazu Factory: core raw materials). 0.0 wt% (Example 16) and 5.0 wt% (Comparative Example 8) were added, and a basis weight of 200 g / g was measured by a square test paper machine based on JIS P 8222 (a method for preparing a test handsheet). m ² so that the front and rear, to prepare a handsheet. Further, as Comparative Example 9, a handsheet was prepared so that the basis weight was around 200 g / m ² without adding PS ash. These were measured in the same manner as in Example 1. The results are shown in Table 5.

(result)
As the amount of ash added increased, paper thickness increased and density decreased. Further, when the addition amount was up to 3% by weight, the specific compressive strength and the breaking length were reduced to 10% or less, but when the addition amount was 5% by weight, the reduction was 10% or more. Further, when the addition amount is 5% by weight, paper roughness and PS ash fall off are also observed, so the addition amount is preferably 3% by weight or less.

Claims (5)

  Paperboard containing 0.01% by weight or more and 3% by weight or less of ash having an average particle size of 20 μm or more and 100 μm or less, comprising paper sludge incineration ash, coal ash, or both. The bulk density of the ash is at 0.1 g / cm ³ or more and 1 g / cm ³ or less, paperboard according to claim 1.   The paperboard of Claim 1 or 2 manufactured using the paperboard raw material which mixed the said ash 0.01 to 10weight% or less with respect to the pulp raw material.   The paperboard according to any one of claims 1 to 3, comprising a plurality of layers and manufactured by applying and laminating the ash between the layers.   A corrugated cardboard core manufactured using the paperboard according to any one of claims 1 to 4.