JP2002294574A - Method for bulky pulp production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a chemithermomechanical pulp having bulkiness, excellent strength and optical characteristics from a high-volume heavy material having >=4.0 Runkel ratio and a thick cell wall. SOLUTION: This method for chemithermomechanical pulp production comprises compressing chips vertically to its fiber direction, immersing the chips in 2-5% alkali solution containing about 0.2-0.5% chelating reagent at a normal temperature for 30 minutes and adding 2-7% alkaline hydrogen peroxide just before primary refining to carry out refining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a chem-thermomechanical pulp from hardwood with high bulk, strength and optical characteristics at low energy, and more particularly to a thick fiber wall having a Runkel ratio of 4.0 or more. Having a volume weight of 450 kg / m ³ or more, a chip produced from a high volume heavy material compressed from a direction perpendicular to the fiber direction, immersed in an alkaline solution containing a chelating agent after compression release, The present invention relates to a method for producing a chem-thermomechanical pulp in which hydrogen peroxide is added together with a chelating agent immediately before primary refining to perform refining.

[0002]

2. Description of the Related Art Problems in the production of mechanical pulp are power saving and quality improvement. Therefore, high-strength refining and chip compression are being studied. R. Lanouette et al. In Tappi J. (K.
N. (K.) Law, et al., Tapp J., 83 (9), 1 (2000).), The refining mechanism has two forces, shear force and compressive force. Is working. Shear force contributes to fiber separation and fragmentation (exposure of fiber surface, external fibrillation, etc.), and compressive force contributes to fiber softening such as deformation, strain, and separation (internal fibrillation). Refining is divided into two stages: defibration and beating. In the beating stage, the fiber is peeled off from the composite intermediate layer (middle lamella + primary wall) including the outer layer of the secondary wall (S1 layer), and the middle layer of the secondary wall ( S2 layer) is fibrillated. Theoretically, high-quality pulp can be produced by suppressing fiber cutting and promoting the destruction between the S1 layer and the S2 layer by compressive force. It is desirable to minimize the force. However, it is not possible with existing refining techniques to operate these two forces separately. Therefore, the focus is on the technique of applying a compressive force before applying a shear force to the chip.

[0003] MJ Sabourin is a coniferous balsam fir
(balsam fir) 48%, spruce (spruce) 45%, pine (p
Using a mixed chip of ine) / hemlock (7%) as a raw material, a process of compressing the chip in a direction perpendicular to the fiber direction is performed by RT Pressafiner ^™ (Andritz) to produce a TMP and evaluate the pulp properties. (MJSabourin, 8
4 ^th Annu.Meeting CPPA Tech.Sect.Preprints, p.B41 (19
98)). As a result, the power consumption is reduced while maintaining the pulp strength as compared with the conventional method.

In a chemical-thermo-mechanical pulp (CTMP) manufacturing process in which chemicals are impregnated into chips before refining and pulp is manufactured after softening the chips, the chips are not only used in the refining process but also in the preceding stage. And a shearing force and a compressive force in the chemical liquid permeation stage. Usually, before refining of TMP, sodium sulfite or caustic soda is used for the purpose of lowering the chip viscoelasticity, softening the fiber, and chemically modifying the lignin and extract contained in the chip. After compressing, the liquid is impregnated. MCBarbe et al. In 1994 disclose the paper “The importance of chip impregnatio
n on refiner pulp quality ”(MCBa
rbe, et al., 80 ^th Annu.Meeting CPPA Tech.Sept.Prepri
nts, p.A155 (1994)). In a screw feeder, chips receive shearing and compressive forces from various directions, but when compressed in a direction perpendicular to the fiber direction, water and air in the fibers are squeezed out and the chips When impregnated inside, absorption and permeation of a chemical solution occur. Also,
It is said that when compressed from the horizontal direction with respect to the fiber surface, the cutting of the fiber occurs due to twisting and exposure of the chip. In some cases, the drug is penetrated in multiple stages in order to sufficiently penetrate the drug solution into the chip, but A. Parkinson et al. Are studying multistage drug solution permeation with a screw feeder (A. Parkinson, et al., Tappi J., 79 (7), 149
(1996)). Black spruce chips with a compression ratio of 3:
After compression to 1 and 5: 1 (both volume ratio), impregnated with aqueous sodium sulfite solution to produce TMP, the chip size decreased as the compression ratio was increased, and the penetration of the drug solution into the chip was improved. It has been reported that the fiber length of the pulp was shortened by cutting, and it is better to increase the compression ratio in order to achieve uniform chemical solution penetration with a screw feeder. Indicates that it cannot be avoided.

[0005] A review of hydrogen peroxide bleaching by Hosoya (S. Hosoya, Japan Tappi J., 5). It is necessary to remove metal ions present in the process when bleaching pulp with hydrogen peroxide.
2 (5), 595 (1998).), It is known that metal ions are contained in wood and include Fe ²⁺ , Cu ²⁺ , Co ²⁺ , and Mn ²⁺ . Although bleaching is achieved by hydrogen peroxide oxidizing and decomposing lignin in wood, when metal ions coexist, the hydrogen peroxide is decomposed by its catalytic action and the bleaching efficiency is reduced. As a workaround,
As shown in Japanese Patent Application No. 57-20636, diethylenetriaminepentaacetic acid, 2-hydroxyethylethylenediaminetriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepenta (methylenephosphonic) acetic acid,
Alternatively, a method of adding these alkali metal salts in advance before adding hydrogen peroxide and forming a complex with metal ions present in the system to prevent decomposition of hydrogen peroxide is applied.

<Background of the Invention> In recent years, in the production of printing paper, the use of hardwood chemishermomechanical pulp, which has less lignin than that of conifers and can be obtained with high white pulp, has been increased from the viewpoint of opacity and printability. ing. However, in general, hardwoods have a higher volumetric weight than conifers, and the wood itself is hard, so that it is difficult to produce fibers. Accordingly, Japanese Patent Application No. 57-20636 (Ala
line peroxide mechanical pulping (APMP method) or Japanese Patent Application No. 59-232269 (Chemi thermo mechanic
al pauping, CTMP method), a method of pretreating a chip with an alkaline chemical has been adopted. However, the method described in Japanese Patent Application No. 57-20636 is carried out using an alkaline solution containing hydrogen peroxide as a chip pretreatment chemical, but this method consumes hydrogen peroxide during the immersion treatment, It was difficult to obtain a uniform bleaching effect. In this method, refining is at normal pressure,
It was difficult to obtain high-strength pulp from hardwood with high volumetric weight. On the other hand, Japanese Patent Application No. 59-232269 discloses a method in which a chip is broken, immersed in an alkali solution, the alkali solution is removed, a sulfite is added, and refining is performed under pressure. However, in this method, the method of breaking the chip is not limited, and the influence on the strength is not considered. In addition, since the chemical added during refining is sulfite, it was difficult to obtain pulp with high whiteness. Therefore, in the prior art, hardwood species suitable for the production of chemi-thermomechanical pulp are limited, and aspen and poplar having a Runkel ratio (double the fiber wall thickness / fiber lumen diameter) of 4.0 or less are used. A low volume heavy material with a thin fiber wall has been used.

<Definition of Runkel Ratio> The Runkel ratio in the text is a parameter published by ROHRunkel in Wachbl. Papierfabr. In 1940. Runkel ratio = (double the fiber wall thickness) / (fiber lumen diameter) ). A larger Runkel ratio indicates a more rigid fiber. The Runkel ratio described in the text is Fiber Lab. (Kajaani)
Is calculated from the fiber width and cell wall thickness measured by the above method.

<Definition of chip compression direction> In the text, the direction of the chip is referred to as "Pu" written by MJ Kocurek and CFBSStevens.
lp andPaper Manufacture ”. Chips are described in three directions: width direction, length direction, and thickness direction. The chip width direction and length direction, or chip thickness direction Performing compression in a direction perpendicular to a plane formed in the length direction is defined in the text as compression perpendicular to the fiber direction.

[0009]

In the conventional method, the use of a low-volume heavy material having a thin fiber wall having a Runkel ratio of 4.0 or less is limited, and there is a limit to a bulking effect and an opacity improving effect. . To meet the diversifying needs of users, the use of high volume heavy materials with higher Runkel ratios and thicker fiber walls was essential.

[0010]

SUMMARY OF THE INVENTION The fiber length of pulp fibers has a large effect on pulp strength. To manufacture high-strength mechanical pulp from hardwood having a shorter fiber length than softwood, fiber damage is suppressed. It is necessary to perform chemical impregnation and refining while doing so. The present invention is for producing a chemi-thermo-mechanical pulp excellent in bulk, strength and optical properties from a high-capacity heavy material having a thick cell wall having a ratio of Runkel 4.0 or more, which was difficult to thermomechanical pulping by a conventional method. As a result of intensive studies, after compressing the chip perpendicularly to the fiber direction, the chelating agent was added to about 0.1 to 0.5.
% For 2 minutes at room temperature in 2-5% alkaline solution,
It has been found that a method of performing refining by adding about 2 to 7% of hydrogen peroxide immediately before primary refining is effective.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The hardwood chips used in the present invention
The shape depends on the type of wood, chipping device, etc.
Although there are variations in dimensions and dimensions, the general chip size is
The length in the fiber direction is 15 to 50 mm, the direction perpendicular to the fiber direction
The width is almost the same, 15-50 mm, and the thickness is 4-7.
mm flat pieces (see FIG. 3). Chips are known
Belt conveyor, air conveyor (suction or pressure feed)
Formula), a chain conveyor, etc.
When performing the compression process, the chips do not overlap as much as possible
It is important to adjust the
You. Specifically, the amount of chips that match the compression
Supply is important, but also equipment
On a conveyor for feeding or on a conveyor for feeding to a compression device
Gates and slits to prevent chips from overlapping
Kakeri, screen (round hole type, slit type, mesh type,
Etc.) or disperse the chips
Do not blow vibration or compressed air
And so on are effective. In the present invention, as described above,
When processing, make sure that the chips do not overlap as much as possible.
But compress the hardwood chip in its thickness direction
The operation is such that the tips overlap and the maximum
Compressed vertically down at 45 ° angle
It is also assumed that In a preferred form of the invention
Before or after impregnation with the chemical, insert the chip vertically or
Compress vertically and do not swell the chip in alkaline chemical solution.
Impregnate with a chemical solution. In addition, it is easy to impregnate
For grades, after compressing the chips,
It can also be immersed in a lucarious solution. Any of these
About whether to adopt
Permeability of chemicals, etc.
It can be appropriately selected in consideration of the concentration of the chemical solution and the like. This compression and
And impregnation, RT Pressaf from Andritz
Ner^TM(RT Pressafiner^TM)
is there. In addition, impregnation of chips is achieved by steaming the chips before compression.
It can be easily done by pre-processing.
If desired, in a two- or three-stage impregnation process with a compression process in between
Can be impregnated. 120 chips impregnated with chemicals
Hold for a sufficient time to soften at temperatures below
You. This depends on the temperature, type and size of the wood chips
This can be done in about 5 minutes to about 180 minutes. At this time
And the wood chips soften, and then the refining process
Facilitates fiber separation. Contained in alkaline chemicals
The chelating agent is the gold that is brought into the chip or from the process.
Forms a complex with metal ions and is added before refining.
Preferred for bleaching alkaline hydrogen peroxide chips
Does not inhibit the decomposition reaction of hydrogen peroxide. The alkaline drug
Liquid impregnated tips contain a chelating agent immediately before refining.
Alkaline hydrogen peroxide is added and bleaching is performed.
This alkaline hydrogen peroxide is described, for example, by R. Lanoutte et al.
(R. Lanoutte, et al., Pulp and Pa
per Can., 101 (5), T143 (2000).), central part of refiner
It is convenient to add together with dilution water. The bleaching chip
The primary refining of the
The operating temperature is 120 ° C. or higher. General refining
A pressurized defibration device is sufficient.
Disc refiner, conical disc refiner,
Double disc refiner, twin disc refiner
Disintegrated by knives. In addition, drift during the refining process
The white chip concentration is preferably about 20-60%.
No. The defibrated bleached pulp is further treated with one or more known
Refined in the inning process and reduced to the desired pulp freeness.
Let This process is performed under normal pressure.
It is preferable to use a general normal pressure type defibrating device, and the concentration is about
It can be performed at 4 to 60%. Higher whiteness
If desired, the pulp may be subjected to one or more known bleaching processes.
Can be further bleached. Manufactured through the above manufacturing process
Weight of 450 kg / m with a Runkel 4.0 ratio or higher ^Three
Thermomechanical pulp manufactured from the above high volume heavy materials
Is bulky, has high whiteness and strong strength,
It can be blended in various printing papers. Printing in that case
The paper is made by a known paper machine.
It is not specified. Also, talc, kaori
Fillers such as calcium carbonate, heavy calcium carbonate and light calcium carbonate
In addition to various commonly used anionic and
On, nonionic or amphoteric retention improver,
In papermaking such as drainage improver, paper strength enhancer and internal sizing agent
Auxiliaries can be used as needed. Furthermore, dyeing
Additives, optical brighteners, pH adjusters, defoamers, pitch control
Slime control agent, slime control agent, etc. added as needed
There is no problem.

[0012]

EXAMPLES Examples will be shown below, but these examples do not limit the scope of the present invention.

Example 1 In order to investigate effective conditions of the present production method, evaluation was first performed at a laboratory level. Experiment Nos. 1 and 2 in Table 1 evaluate the effect of chip destruction during chemical impregnation. In this case, chips were sieved, and chips having a thickness of 4 to 6 mm were used. Chip compression 400mm wide, 100m high
The chips were filled in a container having a length of 400 mm and a depth of 400 mm, and the chips were compressed from above the container at room temperature and at a compression ratio of 2: 1 (volume ratio) using a flat plate compressor (Thailand Machinery Works). If the compression direction is vertical, fill the chips so that they are almost perpendicular to the fiber direction.If the compression direction is random, pack the chips so that the number of chips that are perpendicular to the fiber direction and the number of parallel chips are almost half each. Was filled. Next, an alkali chemical solution containing DTPA as a chelating agent was added to the container in a state where the chip was compressed so as to satisfy the conditions shown in Table 1, and then the chip was swelled by removing the pressure applied to the chip and expanding the chip. The chemical addition rates in the table are based on the absolute dry weight of the chips. After preheating the chips at 50 ° C. for 30 minutes, an alkaline hydrogen peroxide aqueous solution containing DTPA is added, and the primary refining is performed at a concentration of 40% using a laboratory pressure refiner (Kumagaya Riki Kogyo BRP45-300SS). Then, secondary refining was performed using a laboratory normal pressure refiner (Kumaya Riki Kogyo BR-300CB) at a pulp concentration of 20%. Pulp freeness was adjusted to 100 mL with Canadian standard freeness by secondary refining. A handsheet was prepared from the prepared pulp and evaluated. All performance evaluations were performed according to the Tappi standard test method.

[0014]

[Table 1]

With respect to the compression direction of the chips,
Comparing 1 with 2, the pulp with less fiber breakage and higher strength was obtained when the test was performed perpendicular to the fiber direction than when the test was performed randomly. Regarding the alkali immersion conditions, Experiment No. As shown in Figs. 6 and 7, since the defibration was not sufficient with an alkali solution of 2% or less, pulp having a large number of tie fibers and a short fiber length was obtained. 5%
When immersed in the above-mentioned alkaline solution, the defibration is sufficient, but the bulk is reduced, the yield is reduced, and the drainage COD load is increased. Regarding the primary refining temperature, 3
Comparing Nos. To 5, in the case of 100 ° C., the softening of the chips was insufficient, the number of bundled fibers was large, and pulp with a short fiber length was obtained by cutting the fibers. If the alkali immersion time is 5 minutes or less, the softening effect is low, and if it is 180 minutes or more, the yield and the drainage COD load are increased. When the alkali immersion temperature is 120 ° C. or higher, coloring by alkali, a decrease in yield, and an increase in COD load of drainage are caused. On the other hand, the addition of alkali hydrogen peroxide is effective from the viewpoint of prevention of coloring by alkali and bleaching, but when it is 2% or less, it is consumed completely and the effect is reduced. In addition, the method of adding to an alkali solution to be immersed in advance had a lower reached whiteness than the method of adding immediately before refining. Therefore, after compressing the chip perpendicular to the fiber direction, it is immersed in a 2-5% alkaline solution at 50 ° C. for 30 minutes, and immediately before the primary refining, 2% or more of hydrogen peroxide and 0.1% of a chelating agent. The method of performing refining by adding 1 to 0.5% together was effective.

Example 2 Five kinds of wood chips were compressed almost perpendicularly to the fiber direction by a flat plate compressor in the same manner as in Example 1, and impregnated in a chemical under the conditions shown in Table 2. After chemical immersion, pressurized refiner for lab at a concentration of 40% (Kumaya Riki Kogyo BRP45-300S
Primary refining using S), then normal pressure refiner for laboratories (Kumaya Riki Kogyo B
R-300CB) for secondary refining.
The pulp freeness was adjusted to 100 mL by Canadian standard freeness by secondary refining, and the performance of the obtained pulp was evaluated.

[0017]

[Table 2]

Comparative Example Prior art (Chem-thermomechanical pulp method, CTMP
Pulp was manufactured under the conditions shown in Table 3 and compared.

[0019]

[Table 3]

FIG. 1 shows the effect of the Runkel ratio on the sheet density, and shows the results shown in Tables 2 and 3. As is clear from FIG. 1, as the Runkel ratio increases, the sheet density decreases and a bulky sheet is formed.

It is apparent from FIG. 1 that the raw material from which a bulky, that is, low-density sheet can be obtained as compared with conifer radiata pine CTMP produced by the conventional technique is a tree species having a Runkel ratio of 4.0 or more. It is.

Further, it is clear from FIG. 2 that pulp having a Runkel ratio of 4.0 or more is obtained when the pulp is produced from a material having a volumetric weight of 450 kg / m ³ or more.

According to Tables 2 and 3, the specific gravity is 450 kg / m ^3.
If pulp is manufactured by using the above-mentioned high-volume heavy material by the conventional chemi-thermomechanical pulp method (CTMP method), a low-density, ie, bulky pulp can be obtained.
When the sheet properties of the pulp manufactured by the P method and the present invention are compared, a sheet having substantially the same density but high breaking length, specific tear strength, and high specific burst strength is obtained. In comparison, the present invention makes it possible to obtain bulky and high-strength pulp.

[0024]

According to the present invention, the Runkel ratio which has not been used as a raw material for chemi-thermomechanical pulp.
0 or more, allows the use of hardwood with a volume weight 450 kg / m ³ or more high volume weight, it is possible to develop a variety of quality paper products, high yield as a substitute for chemical pulp chemi - thermomechanical pulp The potential for promoting the use of natural resources greatly impacts environmental issues such as the protection of forest resources.

[Brief description of the drawings]

FIG. 1 is a graph showing an influence of a Runkel ratio on a sheet density.

FIG. 2 is a graph showing a relationship between a Runkel ratio and a bulk density.

FIG. 3 is a perspective view showing a shape of a chip used in the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Mitsuhiro Sugino, Inventor, 5-2-1-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. (72) Inventor, Takanori Miyanishi, 5-2-1-1, Oji, Kita-ku, Tokyo F-term in Nippon Paper Industries Co., Ltd. (Reference) 4L055 AA03 AB04 AB12 AB17 AC03 BA08 BA14 BA40 EA18 EA20 EA25 EA32 FA12 FA16

Claims (8)

[Claims] 1. A method for producing a chem-thermomechanical pulp having high bulk, strength and excellent optical properties from hardwood with low energy, comprising: a) a step of compressing a hardwood chip in the thickness direction thereof; Immersing the chip in an alkaline chemical solution containing a chelating agent in a compressed state, or immersing the chip in an alkaline chemical solution containing a chelating agent after compression: c) adding alkaline hydrogen peroxide together with the chelating agent to the immersed chip. Bleaching step: d) Refining the obtained bleached chips immediately after the addition at a temperature of 120 ° C. or more: e) Refining the obtained defibrated pulp under normal pressure to obtain a desired freeness. Obtaining the pulp having the above method. 2. The method according to claim 1, wherein the hardwood chip is a high volume heavy material having a cell wall thickness of Runkel ratio of 4.0 or more and a volume weight of 450 kg / m ³ or more. 3. The method of claim 1, further comprising, after the compression, expanding in an alkaline aqueous solution containing about 0.1 to 0.5% of a chelating agent and about 2% to 10% of sodium hydroxide, and immersing in the chemical solution. Item 7. The method according to Item 1. 4. Immediately before passing the chip impregnated with an alkaline chemical solution according to claim 3 through a refining apparatus, about 0.1 to 0.1.
The method of claim 1 including the step of adding 5% of a chelating agent and about 2% to 5% aqueous alkaline hydrogen peroxide. 5. The alkaline aqueous solution according to claim 3, wherein the diethylenetriaminepentaacetic acid, 2-hydroxyethylethylenediaminetriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepenta (methylenephosphone)
The method according to claim 1, comprising a complexing agent selected from the group consisting of acetic acid, their alkali metal salts and combinations thereof. 6. The method according to claim 1, further comprising the step of refining the bleached chips at 120 ° C. or higher under pressure. 7. The method according to claim 1, wherein a disc refiner is used as the refining device. 8. The method of claim 1, wherein the operation of compressing the hardwood chips in their thickness direction compresses from above when the chips overlap and are at an angle of up to 45 ° with respect to a horizontal plane.