JP5212806B2 - Cooking method of lignocellulosic material - Google Patents

Description

 The present invention relates to a method for cooking lignocellulosic material. More specifically, the present invention relates to a chemical pulp production method that more effectively implements an alkaline cooking method using a quinone compound.

  The main production methods for chemical pulp that have been industrially used so far are the alkaline cooking methods for lignocellulosic materials such as wood, especially the kraft method using an alkaline cooking solution mainly composed of sodium hydroxide and sodium sulfide. Has been. A so-called quinone compound cooking method in which quinone compounds are added to this alkaline cooking solution is also widely known.

  In the quinone compound cooking method, the added quinone compounds oxidize and stabilize the terminal aldehyde groups of cellulose and hemicellulose to prevent the peeling reaction, thereby suppressing the elution reaction of cellulose and hemicellulose. become. On the other hand, the quinone compounds that have become hydroquinone type act on lignin to reduce and dissolve lignin, which itself becomes quinone type. In this way, quinone compounds stabilize cellulose and hemicellulose through their own redox cycle and promote delignification, so that when the pulp kappa number is compared under the same conditions, the yield is improved, It is said to bring about the effect of reducing the amount of active alkali necessary for cooking.

  The kraft method has also been improved in recent years, and a method called the modified kraft cooking, which is characterized by adding the cooking liquor by dividing it at the beginning and in the middle of cooking, has appeared. Improvement is seen and it is also known to use quinone compounds for this modified kraft cooking (for example, Patent Document 1). In this modified kraft cooking, as a method of enhancing the effect of addition by the quinone compound, by using a cooking liquid containing a specific active alkali concentration and a quinone compound concentration as the cooking liquid for treating the lignocellulosic material in the infiltration process at the initial stage of cooking. A method for enhancing the effect of addition by a quinone compound has been proposed. (Patent Document 2)

However, the inventors conducted a modified kraft cooking using a quinone compound with eucalyptus and investigated the behavior of the quinone compound. As a result, the quinone compound present in the lignocellulose material taken out 10 minutes after the start of cooking was added to the amount added. On the other hand, it was about 50%, and it was found that about half of the added quinone compound was discharged without being directly involved in the reaction inside the lignocellulose material. Furthermore, when the quinone compound is added during cooking, that is, the lignocellulosic material is filled with an alkaline cooking solution, it is about 30% less than the amount added, and most of the quinone compound does not penetrate. There was a problem.
JP-A-4-209833 JP 2006-104631 A Junji Tanaka, Proceedings of the 75th Paper Pulp Research Presentation, Tokyo, p26-29, (2008))

 Accordingly, an object of the present invention is to provide a heat treatment method using a quinone compound of a lignocellulosic material as a pretreatment method capable of maximizing the effect of adding a quinone compound in a cooking method of a lignocellulose material. is there.

  That is, the present invention is characterized by the following gist.

(1) In the method of cooking lignocellulosic material using an alkaline cooking solution, the active alkali addition rate is 1 to 5% with respect to the absolute dry weight of the lignocellulosic material as a pre-process of the lignocellulose material cooking step. In an alkaline solution containing an active alkali and a quinone compound, a step of heat-treating the lignocellulosic material at 90 to 120 ° C. for 1 minute or more under the condition that the liquid ratio Y (L / kg) is 0.5 to 4.0 is provided. A method for cooking lignocellulosic material.

(2) In the method of cooking lignocellulosic material using alkaline cooking liquor, the lignocellulosic material is a pre-process of the lignocellulosic material cooking step, and the lignocellulosic material degassing / hydrous treatment step is followed by In an alkaline solution containing an active alkali and a quinone compound with an active alkali addition rate of 1 to 5% based on the absolute dry weight, a lignocellulosic material with a liquid ratio Y (L / kg) of 0.5 to 4.0 A process for cooking lignocellulosic material, comprising the step of heat treating at 90 to 120 ° C. for 1 minute or longer .

(3) In the method of cooking lignocellulosic material using alkaline cooking liquor, the lignocellulosic material is a pre-process of the lignocellulosic material cooking step, wherein the lignocellulosic material is degassed and hydrated. In an alkaline solution containing an active alkali and a quinone compound with an active alkali addition rate of 1 to 5% based on the absolute dry weight, a lignocellulosic material with a liquid ratio Y (L / kg) of 0.5 to 4.0 A process for cooking lignocellulosic material, comprising the step of heat treating at 90 to 120 ° C. for 1 minute or longer .

(4) In the method of cooking lignocellulosic material using an alkaline cooking liquor, the step of degassing / hydrating the lignocellulosic material before the lignocellulosic material cooking step is performed by completely drying the lignocellulose material. In the presence of an alkaline solution containing an active alkali and a quinone compound with an active alkali addition rate of 1 to 5% based on weight, the liquid ratio Y (L / kg) is 90 to 90 under the condition of 0.5 to 4.0. A method for cooking a lignocellulosic material, which is performed by heating at 120 ° C for 1 minute or longer .

(5) The above-mentioned (1), wherein after the step of heat-treating the lignocellulosic material at a temperature condition of 90 to 120 ° C., the lignocellulosic material cooking step is performed without extracting the alkaline solution used for the heat-treatment. )-(3) any lignocellulosic material cooking method.

(6) After the step of deaeration / moisture treatment of the lignocellulosic material in the presence of the alkaline solution, the lignocellulosic material cooking step is performed without extracting the alkaline solution used for the deaeration / water treatment. The method for digesting a lignocellulosic material as described in (4) above, which is characterized by the following.

(7) The concentration of the quinone compound in the alkaline solution is X (%) of the addition rate of the quinone compound with respect to the dry weight of the lignocellulose material, and the ratio (liquid ratio) of the volume of the alkaline solution to the dry weight of the lignocellulose material is The ligno compound according to any one of (1) to (6) above, wherein the quinone compound concentration Z represented by the following formula is 100 ppm or more in terms of anthraquinone when Y (L / kg) Method for cooking cellulosic material.
Z = X · Y ^-1 · 10 ⁴

(8) The method for digesting a lignocellulosic material according to (7) above, wherein X is 0.03% or less.

 By carrying out the present invention, it is possible to provide a pulp having a lower kappa number and a higher yield under the conditions in which the same quinone compound is added as compared with the conventional cooking method, and a reduction in the amount of chemicals used, and a recovery boiler. Load reduction can be achieved. Alternatively, it is possible to save the quinone compound required to bring about the same effect as the conventional cooking method.

 The present invention relates to a cooking method for producing a pulp by cooking a lignocellulosic material using an alkaline solution in the presence of a quinone compound.

  The lignocellulosic material used in the present invention is preferably a wood chip such as conifer or hardwood, but may be called non-wood such as bagasse or straw and is not particularly limited. Examples of wood types include Douglas fir, spruce, pine, cedar, etc. as conifers, and beech, oak, eucalyptus, aspen, acacia, etc. as hardwoods.

  In the present invention, the water content of the lignocellulosic material immediately before the addition of the alkaline solution containing the quinone compound is not particularly limited. That is, the present invention can be applied to any chip in an air-dried state, a water-saturated state, or an absolutely dry state.

 Examples of the cooking method of lignocellulose material to which the present invention can be applied include cooking methods using an alkaline cooking solution such as soda cooking, kraft cooking, sulfite cooking and the like. Moreover, it can be used also for polysulfide cooking obtained by oxidizing a part of kraft cooking liquid which is alkaline cooking liquid.

  Specifically, the lignocellulosic material cooking method is generally a method having an infiltration step and a cooking step, and preferably a continuous cooking method in which these are continuously performed. However, as long as the same effect as the present invention is obtained, other cooking methods such as a so-called batch cooking method may be used. Here, the infiltration step is a step in which the lignocellulosic material is infiltrated into the lignocellulosic material prior to the cooking step and a part of the delignification reaction proceeds. The cooking step is a process in which the delignification reaction of the lignocellulosic material by the cooking liquid is performed. It is a process that proceeds substantially. As a cooking apparatus for continuously digesting lignocellulosic material to which the present invention can be suitably applied, a one-bessel type cooking apparatus in which a top zone, an upper cooking zone, a lower cooking zone, etc. are provided inside the cooking tank, or cooking A two-vessel cooking apparatus in which an osmosis vessel is installed in front of the kettle can be mentioned. Usually, in a one-vessel type cooking apparatus, the top zone is responsible for the osmosis process, and in the 2-vessel cooking apparatus, the osmosis vessel is responsible for the osmosis process.

  Even if any of these digesters or other digesters is used, there are mainly a permeation process in which the liquor is permeated into the lignocellulosic material and a digestion process in which a substantial cooking reaction is performed. It has been practiced to appropriately divide the total cooking liquid used in the cooking system that combines the process and the cooking process, and to supply and add the cooking liquid to at least one location for each of the permeation process and the cooking process. Furthermore, in the cooking process, it is widely performed to divide the cooking zone into a plurality of parts, and to add the cooking liquid separately to each cooking zone and extract the black liquor. Also in the infiltration process, the infiltration of the 2 vessel cooking apparatus It is also practiced to add in two or more portions by adding cooking liquor to the middle stage of the vessel.

 In the present invention, the heat treatment with an alkaline solution containing a quinone compound is preferably performed as a pre-process of the lignocellulose material cooking step. In the case of a batch-type digester, the cooking step here refers to a step in which the lignocellulosic material is treated under alkaline and temperature conditions in which the delignification reaction substantially proceeds in the digester. In the case of a continuous digester, in the case of a 1-vessel type digester, after the top of the digester, in the case of a 2-vessel digester, after the osmotic vessel, the ligno under the alkaline and temperature conditions where the delignification reaction substantially proceeds. It refers to the process in which the cellulosic material is processed. The temperature condition under which the delignification reaction substantially proceeds is generally in the temperature range of 130 ° C. or higher, although it varies depending on the alkaline condition.

  The quinone compounds used in the present invention include not only quinone compounds but also compounds selected from hydroquinone compounds and their precursors, and known compounds can be used as cooking aids. For example, anthraquinone, dihydroanthraquinone (eg, 1,4-dihydroanthraquinone), tetrahydroanthraquinone (eg, 1,4,4a, 9a-tetrahydroanthraquinone, 1,2,3,4-tetrahydroanthraquinone), methylanthraquinone (eg, 1-methylanthraquinone, 2-methylanthraquinone), methyldihydroanthraquinone (eg, 2-methyl-1,4-dihydroanthraquinone), methyltetrahydroanthraquinone (eg, 1-methyl-1,4,4a, 9a-tetrahydroanthraquinone, Quinone compounds such as 2-methyl-1,4,4a, 9a-tetrahydroanthraquinone), anthrahydroquinone (generally 9,10-dihydroxyanthracene), methylanthrahydroquino (For example, 2-methylanthrahydroquinone), dihydroanthrahydroanthraquinone (for example, 1,4-dihydro-9,10-dihydroxyanthracene) or an alkali metal salt thereof (for example, disodium salt of anthrahydroquinone, 1,4- Dihydro-9,10-dihydroxyanthracene disodium salt) and the like, and precursors such as anthrone, anthranol, methylanthrone, and methylanthranol are listed.

  The quinone compounds used in the present invention include those that are soluble in alkaline solutions and those that are hardly soluble. When a quinone compound that is soluble in an alkaline solution is used for pretreatment, it is preferable because it easily penetrates into the lignocellulose material. Examples of such a quinone compound include 9,10-anthrahydroquinone. In the case where a hardly soluble material is used as the alkaline solution, it is permeated into the lignocellulose material by being gradually dissolved after being reduced by the saccharide dissolved in the alkaline solution. For this reason, compared with the case where a quinone compound soluble in an alkaline solution is used, a long pretreatment time is required. Examples of quinone compounds that are hardly soluble in such an alkaline solution include 9,10-anthraquinone and 2-methylanthraquinone. When these are used, it is preferable to use those which are finely powdered and suspended in a liquid because the solubility is increased and the lignocellulosic material is easily penetrated.

 In the present invention, in order to effectively infiltrate the quinone compound into the lignocellulosic material, the quinone compound having a predetermined concentration described later and an alkali necessary for the permeation thereof are included as the liquid that the lignocellulose material contacts for the first time. It is preferable to use an alkaline solution. Hereinafter, such a liquid is also referred to as a permeating liquid.

 When the range of the alkali amount in the permeation liquid is expressed by the active alkali addition rate, it is preferably contained in an amount of 1% to 5% with respect to the dry weight of the lignocellulosic material. If it is less than 1%, the pretreatment time inside the lignocellulosic material becomes long, which is not preferable. If it exceeds 5%, the reaction between the alkali and the polysaccharide tends to occur, and the pulp yield may be lowered.

 Currently, the active alkali addition rate used in general cooking is 13.0 to 24.0%. On the other hand, in the method of dividing and adding white liquor by the modified kraft cooking method in a continuous digester, the proportion of white liquor added together with the quinone compound to the top of the digester (conventional infiltration step) is 40-90% of the total It is. Therefore, in the current modified kraft cooking method, the active alkali addition rate added with the quinone compound is estimated to be 5.2% to 21.6%.

Of course, there is no problem even if an alkaline solution (white liquor) used in the subsequent cooking step is used as the permeating liquid. In addition, black liquor and green liquor can be used as a part thereof. In general, the active alkali concentration of the alkaline solution used in the entire cooking process is 100 to 120 g / L (Na ₂ O conversion).

The active alkali is a measure of the alkalinity in the cooking liquor, and is represented by a value obtained by converting NaOH + Na ₂ S into Na ₂ O weight in the case of the soda method, and NaOH + Na ₂ S in the case of the kraft method. Is the amount of active alkali with respect to the absolute dry weight of the lignocellulosic material, expressed in 100%.

 In general, in cooking using a quinone compound, the effect obtained is increased when the amount of the quinone compound added is increased. In the present invention, the penetrant contains the quinone compound X (%) with respect to the dry weight of the lignocellulosic material, and when the liquid ratio in the system at this time is Y (L / kg), the following formula (1 It is preferable that the quinone compound density | concentration (it contains the water | moisture content in a lignocellulosic material) Z represented by) contains 100 ppm or more in conversion of anthraquinone.

Z = X · Y ^-1 · 10 ⁴ (1)

  Here, when the quinone compound concentration Z is less than 100 ppm, it is within the range used in the conventional cooking method using the quinone compound, and the effect of the quinone compound cannot be sufficiently obtained. The liquid ratio referred to here is the ratio (L / Kg) between the volume of cooking liquor (alkaline solution) used in the batch type digester and the absolute dry weight of the lignocellulosic material in the batch type cooking method. In the continuous cooking method, the ratio of the supply amount (volume) of cooking liquor (alkaline solution) per unit time to the supply amount of lignocellulose material per unit time (absolute dry weight) in a predetermined region of the digester ( L / Kg).

 In the present invention, in order to achieve a quinone compound concentration Z of 100 ppm or more in terms of anthraquinone, a method of increasing the addition rate X of the quinone compound or decreasing the liquid ratio Y in the system can be considered. Employing the latter method is preferable because the effect on the added amount of the quinone compound is increased without increasing the amount of the quinone compound used, and pulp can be produced economically.

 In this invention, it is preferable that the liquid ratio (Y of Formula (1)) in the system at the time of adding the osmotic solution containing a quinone compound is 0.5 L / kg or more. More preferably, it exceeds 2.5 L / kg. In the state where the liquid ratio is 0.5 to 2.5 L / kg, since the volume of the penetrating liquid is small with respect to the lignocellulose material, the quinone compound is expected to penetrate into some lignocellulose materials. . However, within this range, it is possible to homogenize by a mechanical method or the like after the heat treatment, and there is no problem because the quinone compound is uniformly distributed throughout the lignocellulosic material by adding a cooking solution thereafter. However, if the liquid ratio is less than 0.5 L / kg, it penetrates into only a small part of the lignocellulose material, so that the quinone compound does not spread evenly throughout the lignocellulose material in the system, and the effect of the quinone compound Is not preferred because it becomes difficult to express.

 In this invention, it is preferable that the temperature at the time of heat-processing a lignocellulosic material with an osmotic solution is 80-120 degreeC. If the temperature is less than 80 ° C., the quinone compound does not sufficiently penetrate into the lignocellulose material, and the effect obtained by the quinone compound cannot be expected. Moreover, when the temperature of heat processing exceeds 120 degreeC, since decomposition | disassembly of polysaccharide will occur and pulp quality will be impaired, it is unpreferable. More preferably, the temperature of the heat treatment is 90 to 110 ° C.

 In this invention, it is preferable that the processing time at the time of heat-processing a lignocellulosic material with an osmotic solution is at least 1 minute or more. If it is less than 1 minute, the quinone compound does not sufficiently penetrate into the lignocellulosic material, and the effect obtained by the quinone compound cannot be expected sufficiently.

  In the present invention, the method for heat-treating and holding the lignocellulosic material with a penetrant and the structure of the apparatus are not particularly limited as long as the conditions in the present invention are satisfied. For example, a method of immersing the lignocellulose material in an alkaline solution (penetrating solution) containing a high concentration quinone compound in the container, or directly spraying the penetrating solution on the lignocellulosic material in the container can be used.

  In the present invention, when a condition with a sufficiently high liquid ratio is used, a large amount of a quinone compound is required to obtain a penetrant having a high quinone compound concentration. In that case, it is also possible to separate or extract a part of the permeate not permeated into the lignocellulosic material after the heat treatment and add it to the new lignocellulosic material by circulation.

 Hereinafter, cooking using the continuous 1 vessel digester shown in FIG. 1 will be described as an example of a typical cooking apparatus and cooking method. The lignocellulosic material shown in FIG. 1, for example wood chips (1), is supplied to a chip bin (2), heated and degassed in a steaming vessel (3), and passed through a metal trap (4) to a high pressure feeder (5). To the digester top (6) through a conduit (7). On the other hand, alkaline cooking liquid such as white liquor is supplied from the conduit (12). A part of the cooking liquid extracted from the cooking pot top (6) is returned to the high-pressure feeder (5) through the conduit (8). And it mixes with the wood chip heat-deaerated with a high-pressure feeder (5), and is supplied to a digester top part (6) through a conduit | pipe (7). In addition, the general temperature in a steaming vessel (3) is about 80 to 130 degreeC, and the temperature in a digester top part (6) is about 90 to 130 degreeC. In the MCC method, the cooking liquid is distributed to the cooking kettle in order to make the alkali concentration in the cooking process as close as possible. The general distribution ratio is that if the cooking liquor supplied from the cooking liquor introduction pipe (12) is 100, the amount supplied to the top of the cooking kettle (6) is 40 to 90%, which is added during the cooking process. It is 10 to 60% to the branch pipe (13).

 In order to apply the present invention to a pulp cooking method that is generally used at present, it is a pre-process of the lignocellulosic material cooking process, and is active in the post-degassing / moisture treatment process of the lignocellulosic material. It is effective to provide a step of heat-treating the lignocellulose material in an alkaline solution (osmotic solution) containing an alkali and a quinone compound. The deaeration / moisture treatment process of lignocellulosic material referred to here corresponds to the steaming vessel (3) shown in FIG. Examples of places where such a process is provided include a line (chip chute line) and a metal trap (4) for sending to the digester after the steaming process. A high-temperature alkaline solution exists in these places, and for example, by adding a quinone compound using a high-pressure pump, heat treatment satisfying various conditions in the present invention can be performed as an osmotic solution.

 In order to apply the present invention to a pulp cooking method which is generally used at present, it is a pre-process of the lignocellulosic material cooking process, and is active in the pre-process of the lignocellulosic material degassing / moisture treatment process. It is also effective to provide a step of heat-treating the lignocellulose material in an alkaline solution (penetrating solution) containing an alkali and a quinone compound. An example of a place where such a process is provided is the chip bin (2). Here, the lignocellulosic material is provided from an outdoor storage place, and for example, the heat treatment satisfying various conditions in the present invention can be performed by spraying the permeate while heating the material.

 In order to apply the present invention to a pulp cooking method generally used at present, it is a preliminary step of the lignocellulosic material cooking step, wherein the lignocellulosic material degassing / moisture treatment step is performed by using an active alkali and a quinone. It is also effective to carry out in the presence of an alkaline solution (osmotic solution) containing the compound. An example of a place where such an operation is performed is the steaming vessel (3). Here, the deaeration / moisture treatment is performed by spraying the lignocellulosic material with steam. For example, the heat processing which satisfy | fills various conditions in this invention can be performed by spraying here the alkaline solution (penetrating liquid) containing a quinone compound with a vapor | steam.

 In the present invention, in order to promote the penetration of the quinone compound into the lignocellulose material, it is effective to add an auxiliary agent such as a surfactant to the alkaline solution (penetrating solution). Examples of the surfactant include a polyalkylene oxide polymer disclosed in JP-A-57-112485, a copolymer polymer of polyethylene oxide and polypropylene oxide disclosed in US Pat. No. 5,298,120 (1994), Examples thereof include a polymer obtained by adding an alkylene oxide to an aliphatic alcohol disclosed in JP-A-2001-64888. Of course, it is also effective to add a plurality of these in combination.

 In the present invention, the pressure for heat-treating the lignocellulosic material with an osmotic solution is not particularly defined. However, in order to promote the penetration, it is effective to carry out under pressurized or reduced pressure conditions.

 In the present invention, the lignocellulosic material is heat-treated with an alkaline solution (osmotic solution) containing a quinone compound, and then cooked in the cooking process. Conditions in the cooking process, such as temperature and liquid ratio, active alkali addition rate, etc. There is no particular limitation on the conditions, and normal cooking conditions can be employed. For example, conditions such as maximum cooking temperature: 160 ° C., active alkali addition rate: 16%, liquid ratio: 4.0 L / kg, cooking time: 100 minutes can be employed. Under any conditions, since the quinone compound has already penetrated into the lignocellulose material, the effect of a high quinone compound can be obtained. In addition, the present invention does not limit the place where the quinone compound is added in cooking, and there is no problem even if the quinone compound is added to a plurality of locations in each part of the digester, for example, in addition to the locations described above.

 EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, it cannot be overemphasized that this invention is not limited to these Examples.

"Example 1"
The heat treatment and cooking were performed using a device in which piping was connected to a 500 mL stainless steel autoclave so that an alkaline cooking solution and the like could be taken in and out. Chips used as lignocellulosic materials were prepared by cutting eucalyptus wood into a length of about 3 cm in the fiber direction, a width of about 1 cm, and a thickness of about 5 mm. The chip used was air-dried, and the dry weight was 83.6 g. Distilled water was added to the chip in advance so that the amount of water in the chip was 83.6 cc, and the humidity was adjusted while decompressing. The conditioned chip was heated to 100 ° C. in an autoclave. The white liquor used as the alkaline cooking solution used for cooking is prepared using a reagent, and the composition is Na ₂ S: NaOH: Na ₂ CO ₃ = 71.5: 28.5: 22.5 (Na ₂ O conversion) ). The degree of sulfidation was 28.5%. The sodium salt of 1,4-dihydro-9,10-dihydroxyanthracene (manufactured by Kawasaki Kasei Kogyo Co., Ltd., trade name: SAQ) was used as the quinone compound, and the addition rate was expressed as the weight converted to anthraquinone. (same as below.)

<Heat treatment process>
An alkaline solution (penetrating solution) containing a quinone compound that had been heated to 100 ° C. was added to the chip that had been heated in an autoclave. The alkaline solution was obtained by diluting the above white liquor with distilled water, and the active alkali addition rate was 5%. The addition rate of the quinone compound with respect to the lignocellulose material was 0.05% in terms of anthraquinone equivalent weight. The amount of the alkaline solution was 100 cc. Then, it hold | maintained for 3 minutes at 100 degreeC.
Heat treatment conditions Liquid ratio: (83.6 + 100) /83.6=2.2
Quinone compound concentration: 0.05 / 2.2 * 10 ⁴ = 227 ppm

<Cooking process>
Subsequently, a white liquor diluted with distilled water so as to become a 150 cc alkaline cooking solution containing an active alkali with an active alkali addition rate of 11% is added and cooked at a cooking temperature of 155 ° C. until an H factor of 500 is reached. Went.
Cooking conditions Liquid ratio: (150 + 83.6 + 100) /83.6=4.0
Quinone compound concentration: 0.05 / 4.0 * 10 ⁴ = 125 ppm
In addition, H factor is a standard showing the total amount of heat given to the reaction system in the cooking process defined by the following formula (2). From the time when the lignocellulosic material and the cooking liquid are mixed, the cooking is completed. It is a value obtained by integrating up to.

H factor = ∫exp (43.2-16113 / T) dt (2)
Here, T is an absolute temperature at a certain time point, and t is time.

  After cooking, the pulp taken out from the digester was defibrated with a disintegrator and washed thoroughly. Thereafter, it was dried at 105 ° C. for 8 hours, and the pulp yield was measured. The kappa number was measured by TAPPI method T236hm-85. The results of pulp yield and kappa number are shown in Table 1.

"Example 2"
The same as in Example 1 except that the active alkali addition rate of the alkaline solution (osmotic solution) containing the quinone compound used in the heat treatment step was 2% and the active alkali addition rate of the cooking solution used in the cooking step was 14%. The cooking was done. The results of pulp yield and kappa number are shown in Table 1.

“Comparative Example 1”
Cooking was carried out in the same manner as in Example 1 except that the quinone compound was not added to the alkaline solution (penetrating solution) used in the heat treatment step, and 0.05% of the quinone compound was added to the alkaline cooking solution used in the cooking step. The results of pulp yield and kappa number are shown in Table 1.

“Comparative Example 2”
After adding the alkaline solution (penetrating solution) containing the quinone compound to the chips heated in the autoclave in the heat treatment process, hold at 100 ° C for 30 seconds, and then continue to add the alkaline cooking solution. Cooking was performed as in Example 1. The results of pulp yield and kappa number are shown in Table 1.

“Comparative Example 3”
Implemented except that the active alkali addition rate of the alkaline solution (permeate) containing the quinone compound used in the heat treatment step is 0.5%, and the active alkali addition rate of the cooking solution used in the cooking step is 15.5%. Cooking was performed as in Example 1. The results of pulp yield and kappa number are shown in Table 1.

“Comparative Example 4”
Example 1 except that an alkaline solution containing a quinone compound was first added to the chip heated in an autoclave in the heat treatment step, then held at 80 ° C. for 3 minutes, and then an alkaline cooking solution was subsequently added. The cooking was done. The results of pulp yield and kappa number are shown in Table 1.

"Example 3"
<Heat treatment process>
The active alkali addition rate contained in the alkaline solution (penetration solution) initially added to the chip heated in the autoclave was 5%, the addition rate of the quinone compound was 0.072%, and the addition solution amount was 250 cc. Then, it hold | maintained for 3 minutes at 100 degreeC.
Heat treatment conditions Liquid ratio: (83.6 + 250) /83.6=4.0
Quinone compound concentration: 0.072 / 4.0 * 10 ⁴ = 180 ppm
<Cooking process>
Subsequently, 100 cc of an alkaline solution was extracted out of the system from the autoclave.
The liquid ratio at this time is (83.6 + 250-100) /83.6=2.8.
Further, add a white liquor diluted with distilled water so that it becomes a 150 cc alkaline cooking solution containing an active alkali with an active alkali addition rate of 11%, and cook until the H factor reaches 500 at a cooking temperature of 155 ° C. Digestion was performed in the same manner as in Example 1 except that this was performed. The results of pulp yield and kappa number are shown in Table 1.
Cooking conditions Liquid ratio: (83.6 + 250-100 + 100) /83.6=4.0,
Estimated quinone compound concentration: 180 * (2.8 / 4.0) = 126 ppm

Example 4
<Heat treatment process>
When conditioning an air-dried chip used for cooking, 20 cc of an alkaline solution (osmotic solution) containing an active alkali with an active alkali addition rate of 2% and a quinone compound with an addition rate of quinone compound of 0.05% Distilled water was added so that the water content was 83.6 cc, and the humidity was adjusted while reducing the pressure. Then, it hold | maintained at 100 degreeC for 3 minute (s) in the autoclave.
Heat treatment conditions Liquid ratio: 83.6 / 83.6 = 1.0
Quinone compound concentration: 0.05 / 1.0 * 10 ⁴ = 500 ppm
<Cooking process>
Subsequently, a white liquor diluted with distilled water so as to become a 250 cc alkaline cooking liquid containing an active alkali with an active alkali addition rate of 14% is added, and the cooking is performed at a cooking temperature of 155 ° C. until the H factor becomes 500. The cooking was carried out in the same manner as in Example 1 except that. The results of pulp yield and kappa number are shown in Table 1.
Cooking conditions Liquid ratio: (83.6 + 250) /83.6=4.0
The quinone compound concentration is 0.05 / 4.0 * 10 ⁴ = 125 ppm.

“Comparative Example 5”
<Heat treatment process>
When conditioning an air-dried chip used for cooking, 20 cc of an alkaline solution (osmotic solution) containing an active alkali with an active alkali addition rate of 2% and a quinone compound with an addition rate of quinone compound of 0.05% Distilled water was added to a total of 30 cc along with the water content, and the humidity was adjusted while reducing the pressure. Then, it hold | maintained at 100 degreeC for 3 minute (s) in the autoclave.
Heat treatment conditions Liquid ratio: 30 / 83.6 = 0.36,
Quinone compound concentration: 0.05 / 0.36 * 10 ⁴ = 1400 ppm
<Cooking process>
Subsequently, a white liquor diluted with distilled water to add 306.6 cc of an alkaline cooking solution containing an active alkali with an active alkali addition rate of 14% is added, and the H factor becomes 500 at a cooking temperature of 155 ° C. The cooking was performed in the same manner as in Example 1 except that the cooking was performed until the cooking. The results of pulp yield and kappa number are shown in Table 1.
Cooking conditions Liquid ratio: (30 + 303.6) /83.6=4.0
The quinone compound concentration is 0.05 / 4.0 * 10 ⁴ = 125 ppm.

なお、表１中「ＡＡ」の欄には活性アルカリ添加率を記載し、「キノン」の欄にはキノン化合物濃度を記載した。

In Table 1, the “AA” column describes the active alkali addition rate, and the “quinone” column lists the quinone compound concentration.

The figure which shows the example of the continuous 1 vessel digester which applies the cooking method of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wood chip 2 Chip bin 3 Steaming vessel 4 Metal trap 5 High pressure feeder 6 Cooking kettle top part 7 Cooking liquid pipe 8 Cooking liquid pipe 9 Cooking liquid (white liquor) level tank 10 In-line drainer 11 Sand separator 12 Cooking liquid (white liquor) Introduction pipe 13 Cooking liquid (white liquor) introduction pipe (branch pipe added during cooking process)

Claims (8)

In the method of cooking lignocellulosic material using alkaline cooking liquor, as a pre-step of the lignocellulosic material cooking step, an active alkali with an active alkali addition rate of 1 to 5% with respect to the absolute dry weight of lignocellulosic material and In an alkaline solution containing a quinone compound, a step of heat-treating the lignocellulosic material at 90 to 120 ° C. for 1 minute or more under the condition that the liquid ratio Y (L / kg) is 0.5 to 4.0 is provided. Cooking method of lignocellulosic material. In the method of digesting lignocellulosic material using an alkaline cooking liquor, the dry weight of lignocellulosic material is the pre-process of lignocellulosic material cooking process, and after the deaeration / moisture treatment process of lignocellulosic material. In an alkaline solution containing an active alkali and a quinone compound with an active alkali addition rate of 1 to 5% with respect to the lignocellulosic material, the lignocellulosic material is 90 to 90 with a liquid ratio Y (L / kg) of 0.5 to 4.0. A method for cooking a lignocellulosic material, comprising the step of heat-treating at 120 ° C. for 1 minute or longer . In the method of cooking lignocellulosic material using an alkaline cooking liquor, the lignocellulosic material is completely dried before the lignocellulosic material cooking step, before the lignocellulosic material degassing / moisture treatment step. In an alkaline solution containing an active alkali and a quinone compound with an active alkali addition rate of 1 to 5% with respect to the lignocellulosic material, the lignocellulosic material is 90 to 90 with a liquid ratio Y (L / kg) of 0.5 to 4.0. A method for cooking a lignocellulosic material, comprising the step of heat-treating at 120 ° C. for 1 minute or longer . In the method of cooking lignocellulosic material using an alkaline cooking liquor, the lignocellulosic material cooking step is a step preceding the lignocellulosic material degassing / moisture treatment process with respect to the dry weight of the lignocellulose material. In the presence of an alkaline solution containing an active alkali and a quinone compound with an active alkali addition rate of 1 to 5%, at a liquid ratio Y (L / kg) of 0.5 to 4.0, at 90 to 120 ° C. A method for cooking lignocellulosic material, which is carried out by heat treatment for 1 minute or longer . The lignocellulosic material is digested without extracting the alkaline solution used for the heat treatment after the step of heat treating the lignocellulose material at a temperature of 90 to 120 ° C for 1 minute or more. The cooking method of the lignocellulose material as described in any one of -3.   After the step of deaeration / moisture treatment of the lignocellulosic material performed in the presence of an alkaline solution, the lignocellulosic material cooking step is performed without extracting the alkaline solution used for the deaeration / water treatment. The cooking method of the lignocellulosic material according to claim 4. The concentration of the quinone compound in the alkaline solution is X (%) of the addition rate of the quinone compound relative to the absolute dry weight of the lignocellulose material, and the ratio (liquid ratio) of the alkaline solution to the absolute dry weight of the lignocellulose material is Y (L / Kg), the quinone compound concentration Z represented by the following formula (1) is 100 ppm or more in terms of anthraquinone equivalent weight, lignocellulose according to any one of claims 1 to 6, Cooking method of the material.
Z = X · Y ^-1 · 10 ⁴ (1)   Furthermore, X is 0.03% or less, The cooking method of the lignocellulose material of Claim 7 characterized by the above-mentioned.

Images