JP2005220495A - Method for producing mechanical pulp and method for producing paper containing mechanical pulp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing mechanical pulp, capable of preventing troubles caused by containing an anion trash in a papermaking process by eliminating the anion trash contained in the mechanical pulp. <P>SOLUTION: This method for producing the mechanical pulp is characterized by comprising a process of dehydrating pulp slurry containing the mechanical pulp to make ≥20 mass % pulp concentration. It is preferable to perform the dehydration by using a device equipped with a means of feeding the pulp slurry in a gap formed between the travelling two pieces of wires and dehydrating the pulp slurry nipped between the two pieces of wires. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a method for producing mechanical pulp. In particular, the present invention relates to a method for producing mechanical pulp capable of keeping the papermaking system stable by removing anionic trash contained in the mechanical pulp.
The present invention also relates to a method for producing a mechanical pulp-containing paper, which can keep the papermaking system stable by removing anionic trash contained in the mechanical pulp.

Mechanical pulp is produced by mechanically grinding softwood logs and chips, and has a feature of short fiber content. In addition, mechanical pulp has a high yield of over 90%, low density due to relatively stiff fibers, excellent optical properties such as light scattering and opacity, and low density, making it a suitable cushion for paper The effect which brings out the property arises, and the restoring property to compression is good. In addition, when the sheet is formed, the structure becomes rough, so oil absorption and air permeability are good, and printing is excellent.
Mechanical pulp has the above-mentioned characteristics and is not used alone, but is mixed with other pulps and used for newsprint, gravure paper, medium quality paper, coated paper, paperboard and the like.

Mechanical pulp is manufactured from raw materials such as conifers, and raw material chips and logs are mechanically ground as they are, or heated to 100 ° C. to 120 ° C. to soften lignin and ground.
A large amount of anionic trash is usually contained in the pulp produced as described above. Anion trash refers to substances that are negatively charged in the papermaking process in general. Pulp (including fine fibers), fillers (such as calcium carbonate and talc), and various wet-end additive chemicals (pigments, sizes) Agent, antifoaming agent, etc.), resin pitch, elution lignin and the like. In the present invention, it means anionic trash contained in mechanical pulp produced by a mechanical grinding method. If paper making is carried out with such anionic trash contained, the anionic trash becomes sticky in the paper making process due to various auxiliaries and the temperature rise in the process, etc., and adheres to the paper making tool and causes pitch trouble. As a result, quality problems such as paper breakage due to frequent pitch troubles, a decrease in productivity, and frequent spotting occurred.

  When paper making is performed using kraft pulp (KP), deinked pulp (DIP), etc., an operation equivalent to so-called washing is usually performed by diluting raw materials for flow feeding or adjusting the concentration before paper making. . In particular, since the fiber length of KP is generally longer than that of mechanical pulp, it is possible to perform washing using a washing facility using a differential pressure such as a valveless filter. However, since mechanical pulp has a short fiber length, specifically 0.6 to 0.9 mm, the raw material freeness is low, and it is difficult to form a mat layer even if it is attempted to wash using, for example, a valveless filter. For this reason, mechanical pulp is generally used in the papermaking process without undergoing washing or an equivalent process.

  In mechanical pulp, since it is difficult to perform washing as described above, anionic trash is reduced by adding a coagulant or a pitch control agent in order to reduce the amount of anionic trash. More specifically, by adding a cationic coagulant to the anionic trash, and adding an anionic (or cationic) flocculant to the coagulated product, the coagulated anionic trash aggregates and flocs Form. With such a mechanism, the pitch is adsorbed to the pulp, and the pitch concentration is reduced by passing through the process together with the paper stock in a minimal state or by discharging it to the outside of the system. However, a sufficient anion trash reduction effect could not be obtained only by adding such chemicals. In addition, there was a problem of cost increase due to the use of expensive chemicals.

  Therefore, in the conventional mechanical pulp manufacturing process, it is necessary to prevent occurrence of the above-mentioned obstacles in the paper making process due to the inclusion of a large amount of anionic trash, to reduce paper breaks, and to improve production efficiency. is there.

  Accordingly, an object of the present invention is to provide a method for producing mechanical pulp, which can remove the anionic trash contained in the mechanical pulp and prevent a failure caused by the inclusion of the anionic trash in the papermaking process. It is in.

  As a result of intensive studies to achieve the above object, the present inventors have obtained the knowledge that the above object can be achieved by dehydrating slurry containing mechanical pulp and setting the pulp concentration to a specific concentration or higher. Completed the invention.

This invention is made | formed based on the said knowledge, and has a process which spin-dry | dehydrates the pulp slurry containing mechanical pulp and makes a pulp density | concentration 20 mass% or more, It provides the mechanical pulp manufacturing method characterized by the above-mentioned. Is.
According to the said mechanical pulp manufacturing method, the mechanical pulp which can remove the anion trash contained in a mechanical pulp and can prevent the disorder | damage | failure which generate | occur | produces by including an anionic trash in a papermaking process can be manufactured.
It is preferable that the cation requirement amount by anion trash in the pulp slurry after dehydration is less than 0.3 meq / L.
In the mechanical pulp manufacturing method, the pulp slurry is dehydrated by supplying the pulp slurry to a gap formed between the two traveling wires, and dewatering the pulp slurry sandwiched between the two wires. It is preferable to carry out by an apparatus provided with means.

Further, the present invention dehydrates a pulp slurry containing mechanical pulp to obtain a pulp slurry having a pulp concentration of 20% by mass or more, dilutes the obtained pulp slurry with water, and uses a pulp slurry in which the pulp concentration is diluted. The present invention provides a method for producing a mechanical pulp-containing paper, which is characterized in that the paper is made.
It is preferable that the amount of cation required by anion trash in the pulp slurry is less than 0.3 meq / L.
In the manufacturing supplement method for the mechanical pulp-containing paper, the pulp slurry is dehydrated by supplying pulp slurry to a gap formed between the two traveling wires, and the pulp sandwiched between the two wires. It is preferable to use an apparatus equipped with a means for dewatering the slurry.

According to the mechanical pulp manufacturing method of the present invention, anion trash contained in the pulp can be reduced, so that troubles such as pitch troubles caused by the inclusion of anion trash in the paper making process can be prevented.
Further, according to the method for producing mechanical pulp-containing paper of the present invention, since mechanical pulp having a low anionic trash content is used, it is possible to prevent obstacles such as pitch troubles caused by the inclusion of anionic trash in the papermaking process. it can.

Hereinafter, the mechanical pulp manufacturing method of the present invention will be described.
The mechanical pulp manufacturing method of the present invention is characterized by having a step of dehydrating a pulp slurry containing mechanical pulp to bring the pulp concentration to 20% by mass or more.

  As the mechanical pulp applied in the present invention, those conventionally known as mechanical pulp can be used without particular limitation. Examples of such mechanical pulp include groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), thermoground wood pulp (TGW), and pressure. Examples include ground wood pulp (PGW) and chemi-ground pulp (CGP).

  The mechanical pulp used is broad-leaved wood, softwood, etc., which is a raw material for mechanical pulp, or a process normally performed for producing mechanical pulp from chips, that is, a grinding process, a fine-selection process, a cleaning process, etc. Usually, the thing of the form of the slurry containing mechanical pulp is used.

  In the grinding process, the raw wood and chips that are raw materials may be made into pulp by a conventionally known method. For example, the raw wood is brought to a temperature of about 100 to 120 ° C., and the lignin contained in the raw materials is softened and then finely divided. The method of doing is mentioned. For example, a grinder, a disc refiner, or the like is used as an apparatus for finely grinding the raw material.

  In the manufacturing process of mechanical pulp, raw materials such as raw wood are finely crushed and ground into pulp by the above-mentioned grinding process, but at this time, foreign matter other than small wooden pieces and pulp fibers that are not sufficiently ground are included. Therefore, it is preferable to remove foreign substances other than these small pieces of wood and pulp fibers that have not been crushed by a selection process.

The mechanical pulp after the selection process is obtained as a pulp slurry, and the pulp concentration in the pulp slurry is usually about 5 to 10% by mass. In the mechanical pulp manufacturing method of the present invention, the pulp slurry is dehydrated. And a step of setting the pulp concentration to 20% by mass or more. The pulp concentration of the pulp slurry after dehydration is preferably 20 to 30% by mass, and more preferably 25 to 30% by mass. When the pulp concentration exceeds 30% by mass, there may be a problem that the operability is lowered or the cost is increased. In the mechanical pulp manufacturing method of the present invention, the anion trash contained in the pulp slurry is removed by dehydrating the pulp slurry. Thereby, the disorder | damage | failure which generate | occur | produces by anion trash being contained in a papermaking process can be prevented. The amount of cation required by anion trash contained in the pulp slurry is preferably less than 0.3 meq / L, and more preferably less than 0.2 meq / L. If the required amount of cation due to anion trash in the pulp slurry is 0.3 meq / L or more, pitch trouble may occur in the paper making process. Therefore, it is preferable that the cation requirement by anion trash in the pulp slurry is less than 0.3 meq / L by dehydration. Usually, it is considered that the required amount of cation by anion trash in the pulp slurry is less than 0.3 meq / L by dehydrating the pulp slurry so that the pulp concentration becomes 20% by mass or more.
Although there is no restriction | limiting in particular in the method of dehydrating a pulp slurry and making a pulp density | concentration 20 mass% or more, For example, implementing by the following method is preferable.

In the mechanical pulp manufacturing method of the present invention, the pulp slurry is dehydrated by supplying the pulp slurry to a gap formed between the two traveling wires, and the pulp slurry sandwiched between the two wires. It is preferably carried out by an apparatus equipped with a means for dehydrating.
FIG. 1 shows an example of an apparatus for dehydrating pulp slurry in the mechanical pulp manufacturing method of the present invention. FIG. 1 is a schematic configuration diagram of an apparatus for dehydrating a pulp slurry in the mechanical pulp manufacturing method of the present invention.

  In the dehydrating apparatus shown in FIG. 1, the two wires (wire nets) 3 and 4 each form a loop. In such a dewatering device, the pulp slurry 2 ejected from the head box 1 is sandwiched between wedge-shaped gaps formed by the two wires 3 and 4, and the wires 3 and 4 are wrapped by the suction roll 5, and the wire A suction force is applied to the range where 3 and 4 are wrapped, and dehydration from the pulp slurry 2 proceeds.

  A large number of dewatering holes are arranged at regular intervals on the outer peripheral surface of the suction roll 5. Each dewatering hole has its center line oriented in the normal direction of the roll circumference, that is, is arranged perpendicular to the peripheral surface, and communicates with an internal space formed inside the suction roll 5. A suction box is provided in the internal space, and a suction force by a negative pressure is applied only to a range where the wires 3 and 4 are wrapped to dehydrate the pulp slurry.

  In FIG. 1, one suction roll is disposed, but a plurality of such suction rolls may be used. By using an apparatus having a plurality of suction rolls, the dehydration effect is improved. In addition, although the dewatering apparatus shown in FIG. 1 dehydrates the pulp slurry using a suction roll, a dewatering apparatus other than the suction roll may be used.

  Since mechanical pulp has a short fiber length, using a valveless filter conventionally used for washing and dewatering pulp has been difficult to wash because a mat layer is not formed. By using the apparatus described above, the pulp slurry containing mechanical pulp can be easily dehydrated. Moreover, since the anion trash melt | dissolved in a pulp slurry is removed with water by dehydrating the pulp slurry containing mechanical pulp and making a pulp density | concentration 20 mass% or more, the amount of anion trash in a pulp slurry Can be reduced.

  In the mechanical pulp manufacturing method of the present invention, since the amount of anionic trash in the pulp slurry can be reduced, the anionic trash is sticky and can prevent pitch trouble caused by adhering to the papermaking tool.

The mechanical pulp obtained by the mechanical pulp manufacturing method of the present invention can be blended in various printing papers, information papers and the like.
The mechanical pulp obtained by the mechanical pulp manufacturing method of the present invention includes pulp other than mechanical pulp, talc, kaolin, heavy calcium carbonate, light calcium carbonate, etc., used for manufacturing various printing papers, information papers, etc. In addition to the above fillers, various commonly used anionic, cationic, nonionic or amphoteric yield improvers, drainage improvers, paper strength enhancers, internal sizing agents, etc. Agents can be used as needed. Furthermore, dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents, coagulants, and the like can be added as necessary. In the mechanical pulp manufacturing method of the present invention, since the amount of anionic trash in the pulp slurry is reduced, it is possible to reduce the amount of chemicals used, for example, pitch control agents and coagulants, by reducing the cation requirement. .

  The papermaking method when making printing paper, information paper, etc. using the mechanical pulp obtained by the mechanical pulp production method of the present invention is not particularly limited, but for example, a long net paper machine, twin wire papermaking Machine, combination paper machine, round net paper machine, Yankee paper machine and the like can be used.

Next, the manufacturing method of the mechanical pulp containing paper of this invention is demonstrated.
In the method for producing mechanical pulp-containing paper of the present invention, a pulp slurry containing mechanical pulp is dehydrated to obtain a pulp slurry having a pulp concentration of 20% by mass or more. The obtained pulp slurry is diluted with water, and the pulp concentration is diluted. Papermaking is performed using the pulp slurry. In addition, it is preferable to use a pulp slurry having a pulp concentration of 20 to 30% by mass after dehydration, and it is more preferable to use a pulp slurry having a pulp concentration of 25 to 30% by mass.
By using a pulp slurry having a pulp concentration of 20% by mass or more, anion trash contained in the pulp slurry can be removed, and failures caused by inclusion of anion trash in the paper making process can be prevented. The amount of cation required by anion trash contained in the pulp slurry is preferably less than 0.3 meq / L, and more preferably less than 0.2 meq / L. If the required amount of cation due to anion trash in the pulp slurry is 0.3 meq / L or more, pitch trouble may occur in the paper making process. Therefore, it is preferable that the amount of cation required by anion trash in the pulp slurry is less than 0.3 meq / L by dehydration. Usually, it is considered that the required amount of cation by anion trash in the pulp slurry is less than 0.3 meq / L by dehydrating the pulp slurry so that the pulp concentration becomes 20% by mass or more.

In the method for producing mechanical pulp of the present invention, there is no particular limitation on the method of dehydrating the pulp slurry so that the pulp concentration is 20% by mass or more. However, for example, the following method is preferable.
In the method for producing mechanical pulp-containing paper of the present invention, the pulp slurry is dehydrated by supplying the pulp slurry to a gap formed between the two traveling wires and sandwiched between the two wires. It is preferably carried out by an apparatus equipped with a means for dewatering the pulp slurry. As such an apparatus, those described above can be used.

  In the method for producing mechanical pulp-containing paper of the present invention, the pulp slurry is dehydrated to obtain a pulp slurry having a pulp concentration of 20% by mass or more, and the obtained pulp slurry is diluted with water and used. The concentration is usually about 2 to 5% by mass.

  In the method for producing mechanical pulp-containing paper of the present invention, the pulp slurry is dehydrated to obtain a pulp slurry having a pulp concentration of 20% by mass or more, and the obtained pulp slurry is diluted with water and used. Since the pulp slurry containing mechanical pulp is dehydrated to a pulp concentration of 20% by mass or more, the anionic trash dissolved in the pulp slurry containing mechanical pulp is removed together with water, and the amount of anionic trash in the pulp slurry is reduced. doing.

In the method for producing mechanical pulp-containing paper of the present invention, paper is made by diluting a pulp slurry having a pulp concentration of 20% by mass or more with water. The pulp slurry is generally used in addition to fillers such as pulp other than mechanical pulp, talc, kaolin, heavy calcium carbonate, and light calcium carbonate, which are used to produce various printing papers and information papers. Various anionic, cationic, nonionic or amphoteric yield improvers, freeness improvers, paper strength enhancers, internal additive sizing agents, and other internal additives for papermaking can be used as necessary. . Furthermore, dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents, coagulants, and the like can be added as necessary. The papermaking method is not particularly limited, and for example, a long paper machine, a twin wire paper machine, a combination paper machine, a round paper machine, a Yankee paper machine, or the like can be used. Paper obtained by the method for producing mechanical pulp-containing paper of the present invention is printing paper, information paper, or the like.
In the method for producing the mechanical pulp-containing paper of the present invention, since the pulp slurry having a reduced amount of anionic trash is used, the anionic trash is sticky and can prevent pitch trouble caused by adhering to a papermaking tool. The papermaking system can be stabilized.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto.
Example 1
The Chilean pine wood 90 days after felling was cut into 1m length using a slasher and the original skin was peeled off using a drum barker. Next, it is rotated at 330 rpm under a pressure of 2 atm using a pressure type grinder manufactured by Tampera, and is ground with 120 ° C. shower water. A piece of wood or three bars (fibers bundled from several to several dozen) were removed to obtain mechanical pulp.

  The pulp concentration of the pulp slurry containing the mechanical pulp obtained as described above was 10% by mass. Next, the obtained pulp slurry was dewatered by a double wire thickener manufactured by Maruishi Seisakusho Co., Ltd., and the mechanical pulp concentration was adjusted to about 20% by mass.

Next, the pulp slurry was diluted with water so that the pulp concentration was 2% by mass, and refined with a double disc refiner manufactured by Aikawa Co., Ltd., to a freeness of 90 cc. To 100 parts by mass of the obtained mechanical pulp, 50 parts by mass of LBKP and 1.5 parts by mass of sulfuric acid band were added, and a paper was made at 500 m / min with a long net paper machine using a flocculant and a coagulant. A base paper having a basis weight of 64 g / m ² was obtained. In the paper making process, no troubles such as pitch trouble occurred.

In addition, the anion trash amount of mechanical pulp was measured by measuring the cation requirement. The method is as follows. Note that a small amount of cation demand means a small amount of anion trash. The results are shown in Table 1.
The amount of cation required by anion trash was determined by titration with DADMAC (diallyldimethylammonium chloride) using a particle charge meter (particle charge detector).

Example 2
Mechanical pulp was made by Maruishi Seisakusho Co., Ltd., and dehydrated with a double wire thickener, and the operation was performed in the same manner as in Example 1 except that the pulp concentration was 30% by mass. It was. In the paper making process, no troubles such as pitch trouble occurred.
The amount of cation required by anion trash was measured in the same manner as in Example 1. The results are shown in Table 1.

Example 3
After removing heavy foreign matter from the spruce chip with a chip screen, preheat it for 2 minutes at a glass transition temperature of 120 ° C of lignin, soften the lignin, and then refer to it with a single disc refiner at a concentration of 40% under a pressure of 1.2 atm. Inning. Subsequently, refining was performed using a double disc refiner, and wood pulp, slivers and shives were removed using a screen and a cleaner to obtain mechanical pulp. The pulp concentration of the obtained mechanical pulp was 4% by mass. This pulp was dewatered with a double wire thickener manufactured by Maruishi Seisakusho until the pulp concentration reached 30% by mass. Subsequently, the pulp slurry having a pulp concentration of 30% by mass was diluted with water so that the pulp concentration became 2% by mass, and the same operation as in Example 1 was performed to obtain a base paper. In the papermaking process, no troubles such as pitch trouble occurred.
The amount of cation required by anion trash was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1
The mechanical pulp was dewatered by a double wire thickener manufactured by Maruishi Seisakusho Co., Ltd., and the operation was performed in the same manner as in Example 1 except that the pulp concentration was 15% by mass. A base paper having a basis weight of 64 g / m ² was obtained. Obtained. Incidentally, 0.3 mm ² or more defects caused by the resin pitch in the paper making process occurs 1 m ² per one or more at Omron transmission-reflection combination type defect detector during 60,000m papermaking became pitch troubles .
The amount of cation required by anion trash was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2
A base paper having a basis weight of 64 g / m ² was obtained in the same manner as in Example 1 except that dehydration was not performed using a double wire thickener manufactured by Maruishi Seisakusho. Incidentally, 0.3 mm ² or more defects caused by the resin pitch in the paper making process occurs 1 m ² per one or more at Omron transmission-reflection combination type defect detector during 60,000m papermaking became pitch troubles .
The amount of cation required by anion trash was measured in the same manner as in Example 1. The results are shown in Table 1.

  As is apparent from Table 1, according to the mechanical pulp production method of Examples 1 to 3, the cation requirement due to anion trash of the mechanical pulp before preparation in the paper making process can be suppressed to a low level. It is possible to reduce fluctuations during adjustment of the cation requirement by the coagulant. As a result, it is possible to reduce factors that deteriorate the papermaking properties such as the yield and pitch of the raw material. On the other hand, in Comparative Examples 1 and 2, the amount of anion trash is large, that is, the amount of cation required is large, and it becomes difficult to control the aggregation and coagulant. This will improve paper quality and cause defects.

It is a schematic block diagram of the apparatus for performing dehydration of a pulp slurry in the mechanical pulp manufacturing method of this invention.

Explanation of symbols

1 Head box 2 Pulp slurry 3 Wire 4 Wire 5 Suction roll

Claims (6)

A method for producing mechanical pulp, comprising the step of dehydrating a pulp slurry containing mechanical pulp to bring the pulp concentration to 20% by mass or more. The mechanical pulp manufacturing method of Claim 1 whose cation request | requirement amount by anion trash in the pulp slurry after dehydration is less than 0.3 meq / L. Dehydration of pulp slurry,
The method according to claim 1, wherein the pulp slurry is supplied to a gap formed between two traveling wires and is provided by a device having means for dewatering the pulp slurry sandwiched between the two wires. The mechanical pulp manufacturing method as described. A pulp slurry containing mechanical pulp is dehydrated to obtain a pulp slurry having a pulp concentration of 20% by mass or more, and the obtained pulp slurry is diluted with water, and is made using a pulp slurry having a diluted pulp concentration. A method for producing mechanical pulp-containing paper. The manufacturing method of the mechanical pulp containing paper of Claim 4 whose cation request | requirement amount by the anion trash in the said pulp slurry is less than 0.3 meq / L. Dehydration of pulp slurry,
The method according to claim 3 or 4, wherein pulp slurry is supplied to a gap formed between the two traveling wires, and the apparatus includes means for dewatering the pulp slurry sandwiched between the two wires. The manufacturing method of the mechanical pulp containing paper of description.

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