JPH0345149B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention uses a chlorine-free, sulfur-free cooking chemical solution using water as a solvent, and uses a single-stage cooking method under normal pressure to produce a chemical with high whiteness from a wide range of non-wood cellulose raw materials. The present invention relates to a method and apparatus for producing pulp quickly and with high yield. [Prior art and its problems] Non-wood cellulose raw materials generally have coarser and softer structures than wood, and have a lower lignin content. Therefore, cooking chemicals penetrate well and cooking is easy.
Similar to the production of wood pulp, if the AP method or KP method is applied, it is possible to digest at a temperature 10 to 20 degrees Celsius lower (140 to 160 degrees Celsius) than wood, but the yield of pulp is lower than the cellulose content of the raw material. It has the disadvantage of being extremely low, and much research has been carried out for a long time to improve this disadvantage. One of the methods for this purpose is to perform a light chemical treatment and perform mechanical defibration using a refiner or beater as a post-treatment, as in the case of increasing the yield of wood pulp, to obtain a high-yield pulp. SCP, CGP, and CTMP methods have been tried and used for pulping some raw materials with low lignin content, such as hemp, for a long time. Furthermore, in research reports on improvements, only the conditions for chemical treatment were studied, and for mechanical treatment, the use of refiners and beaters was common knowledge to the extent that there was no room for improvement. That is, it is common knowledge that hemp is digested with an alkali and then defibrated using a beater or the like to form pulp. In addition, in research aimed at increasing the yield of bast pulp from kozo, mitsumata, etc., Takaga, Takamura, Samejima et al. Using an aqueous solution of ammonium oxalate as the cooking chemical, the pulp was cooked under normal pressure and then treated in a lumpen mill for defibration, successfully producing high-yield pulp. Akamatsu, Ueshima, Fujii, Yoshiwara et al. Manila hemp (abaca)
After biochemical treatment using white-rot fungi, mechanical defibration treatment (bio-RMP method) using Disccliff Iner was used to successfully obtain pulp with low strength but high yield. [29th Lignin Symposium Abstracts, p. 79 (1984)]. Mr. Tachibana, Mr. Isoda, Mr. Nomura et al. (Special Publication No. 41-4801) mainly used hydrogen peroxide,
By using a mixture of sodium hydroxide and sodium silicate as an auxiliary agent as a cooking chemical, hemp is cooked at 60 to 120°C for 4 hours, and then bleached with hypochlorite. Hemp pulp has been successfully obtained in high yield. However, when we tried this method again, we found that when cooking under normal pressure, complete pulping that can be applied to the bleaching process is not possible without mechanical defibration as a post-treatment. It turns out that the use of a defibration step is essential. In addition, the mechanochemical method uses rice straw, wheat straw,
It is known as a method for obtaining pulp from agricultural waste containing cellulose such as bagasse and hemp husks. This method uses a high-concentration disintegrating machine such as a hydropulper, which can easily disintegrate pulp or waste paper by creating a strong vortex in water. By applying a concentrated aqueous sodium hydroxide solution and adding the above-mentioned cellulose raw material instead of pulp or waste paper, the unbleached pulp can be directly converted to 60-70% by treating it at a temperature of about 100°C under normal pressure for about 1 hour. This is a simple pulping method that provides high yields. However, with this method, the knots are not pulped, and the resulting pulp has a lot of dirt and low whiteness.Although bleaching is possible, it contains a lot of lignin and requires a large amount of bleaching agent. For this reason, the unbleached pulp was only used as a raw material for lower-grade wrapping paper and paperboard. As mentioned above, pulping with mechanical defibration can dramatically improve the pulp yield, but on the other hand, it requires a defibration device such as a beater, a lumpen mill, or a refiner, and the energy applied is half-digested. It is also used to break down cellulose when breaking down the structure of cellulosic raw materials in the state, resulting in the production of a significant amount of bound fibers and short fibers. Therefore, increasing the yield by such a pulping method requires a significant amount of power, and bleaching the fibers becomes difficult, which increases the basic unit of bleaching agent. This also causes inconveniences such as deterioration of the pulp. Recently, research has been published on adding solvents such as alcohol to cooking chemicals and cooking cellulose raw materials in organic solvents such as phenol in order to improve pulp yield and accelerate cooking. However, there has been no example of success in obtaining high-quality pulp in high yield through short-time cooking under normal pressure. Previously, the present inventors used a mixture of an alkaline solution of hydrogen peroxide and a chelating agent, anthraquinones, etc. as auxiliaries as a cooking chemical solution.
We succeeded in obtaining high-quality pulp from a wide variety of non-wood and wood cellulose raw materials at high yields by treating it at ℃ for just 1 hour without going through the mechanical defibration process (PA method, Japanese Patent Publication No. 59-9677). No. etc.). According to this PA method, pulp can be obtained at a higher yield than conventional chemical pulp manufacturing methods such as PA method and KP method.
Pulp has many advantages, including being white in color, strong, and easily bleached. However, the SCP method
Although it does not require a mechanical defibration process or equipment compared to the CGP method, the yield is still low, and the pressure resistance is lower than that of the chemical mechanical method or the method of Tachibana, Isoda, and Nomura because it cooks at a higher temperature. It also had drawbacks, such as the need for a digester. [Problems to be solved by the invention] The present invention significantly accelerates cooking in the pulping of non-wood cellulose raw materials using the above-mentioned alkaline solution of hydrogen peroxide as a cooking chemical. The object of the present invention is to provide a method and apparatus for obtaining high-quality pulp with high whiteness at a high yield without undergoing a mechanical defibration step. [Means for Solving the Problems] The present inventors have been conducting research for many years in order to rationalize a wide range of methods for producing non-wood pulp and wood pulp. First, the present inventors developed the new
The development of the PA method has made it possible to obtain unbleached pulp with relatively high whiteness. Furthermore, the present inventors have made use of the advantages of this PA method, which do not require a mechanical defibration process and equipment, and do not require a high-pressure, high-temperature cooking process or pressure-resistant cooking equipment. I have continued my research with the idea that if a new method were developed, the pulp industry could be greatly streamlined. We have now discovered that when non-wood cellulose raw materials such as abaca and bagasse are added to a PA cooking chemical solution heated under normal pressure, an extremely thin pulped layer forms on the surface of the raw materials in an extremely short period of time. By wiping off this pulped layer, new internal surfaces are revealed one after another and pulped, and almost all of the raw material is heated at a temperature below the boiling point under normal pressure without mechanically destroying the raw material structure. We discovered that it can be turned into pulp in an extremely short time. The present invention was completed based on this knowledge. That is, according to the present invention, a mixture consisting of water, hydrogen peroxide, a hydrogen peroxide generator, an alkali hydroxide, and a hydrogen peroxide stabilizer, or a mixture containing anthraquinones is used as a cooking chemical liquid, Wood cellulose raw material is used as pulp raw material, and both the cooking chemicals and pulp raw material are supplied to the digester at a liquid ratio of 2 to 15/Kg, and the mixture is forcibly stirred under normal pressure and at a temperature below the boiling point. By doing so, one stage of high-speed cooking is performed, and the resulting digested product is ground.
A method for producing unbleached pulp with high whiteness from non-wood cellulose raw materials (hereinafter referred to as rapid PA method), which is characterized by obtaining selected pulp only by removing impurities such as lees and dust without beating or disintegrating. ：FPA Act)
is provided. In addition, the FPA method implementation equipment has the function of forcibly stirring and mixing a mixture of pulp raw materials and cooking chemicals supplied at a low liquid ratio while heating and/or keeping the mixture at or near the boiling point under normal pressure. Consists of a combination of a cooking reaction device consisting of a corrosion-resistant container equipped with at least one of an agitator and a high concentration pump, and a device capable of separating and recovering impurities such as lees and dust from the cooked product and selected unbleached pulp. A device (hereinafter abbreviated as FPA device) is provided. This time, the inventors used abaca as a pulp raw material by cutting it into lengths of 30 to 40 mm and using it for cooking. In this case, as shown in (A) of Table 1 below, sodium hydroxide (as Na ₂ O) is added to the raw materials (hereinafter expressed as bone dry).
15%, hydrogen peroxide 7%, and a chelating agent (1-hydroxyethane-1,
A cooking chemical solution was prepared using 0.3% of 1-diphosphonic acid), 0.1% of quinones (t-butylanthraquinone), and water. This cooking chemical solution was placed in a 20-volume stainless steel container with a diameter of 30 cm and equipped with a stirrer that can be heated and kept warm. After heating to 90°C, 1 kg of abaca was added at a liquid ratio of 10/Kg. The mixture was kept at ℃ and the stirrer was rotated at 150 revolutions per minute to forcibly stir and mix the raw materials so that the raw materials rubbed against each other to facilitate wiping off the thin pulp layer on the surface. In the above operation, although the cooking temperature is extremely low compared to that of the conventional PA method, the cooking progresses rapidly, and the original shape of the raw material is quickly lost.
The presence of bound fibers was also no longer observed. After 60 minutes, the cooking was stopped, and the pale yellow, mushy, pulpy digestate was taken out, diluted with water, and treated with a 12/1000 cut flat screen. 60.2%
72.3, which is extremely high for unbleached abaca pulp (hereinafter referred to as rapid PA cooking pulp: FPAP).
% (3.2% lees rate, total yield
75.5%). As shown in Table 1-(B) below, the conventional PA method requires cooking at 150°C for 60 minutes, resulting in a total yield of 54.9% (picked yield 48.5, lees ratio 6.4).
%), although the cooking temperature is 60°C lower, the lees ratio is low, and both the selective yield and total yield are low.
It improved by 20%. The resulting unbleached pulp had a high kappa number, but the Hunter whiteness was PAP, which has been considered to have a high whiteness for abaca chemical pulp.
This shows that it is more than 20% higher than the previous year. Furthermore, as a result of our research, the present invention method can be applied not only to leaf fibers such as abaca and sisal, but also to fibers such as bagasse, rods such as rice straw, gampi, mitsumata, etc., as in the PA method. It can be applied to various non-wood cellulose raw materials such as bast containing pectocellulose such as bast containing pectocellulose, bast containing a significant amount of lignin such as kenaf and juute, seed wool such as cotton linters and kapoku. It has been found that unbleached pulp with high whiteness can be produced at an extremely high yield. It has also been found that the present invention can greatly contribute to saving cooking time and cooking chemicals in pulp production, and to simplifying the pulping process and equipment. The non-wood cellulose raw material used as a pulp raw material in the present invention is supplied to the digester in a length of about 5 to 150 mm. When the non-wood cellulose raw material is long, it is cut into pieces of about 5 to 150 mm in advance, and when it is short, it is used as is. The reason why long non-wood cellulose raw materials are cut prior to cooking is to prevent non-wood cellulose raw materials from being too long and tightly intertwined with each other during stirring and mixing during cooking. On the other hand, if the fibers are cut too short, the shape of the fibers constituting the pulp and the properties of the pulp will be significantly impaired, leading to a decrease in pulp strength such as tear strength, which is not preferable. Therefore 5
It is preferable to cut ~150 mm, but the optimal length of the raw material in the FPA method varies depending on the type of raw material plant. In general, seed hair is short, preferably cut into 5-20 mm pieces. Hemp and bast are longer, preferably cut into 25-80 mm pieces. It is also desirable to cut rods into longer lengths of 50 to 150 mm.
This process can also be carried out inside the pulp mill.
It is also possible to do this before transporting it to the factory.
As the device for cutting the raw material, a device capable of cutting flexible and long raw materials such as a cutting machine for rice straw, mulberry, etc. can be used. As the cooking chemical, it is possible to use the same PA cooking chemical as conventionally used for PA cooking at high pressure and high temperature, and since it has become possible to cook at low temperatures, hydrogen peroxide can be used in the PA method. It has become possible to replace part or all of the conventional chelating agent used as a stabilizer with a stabilizer made of water glass. The ratio of liquids that can be mixed and stirred to wipe away the thin pulp layer that forms on the surface of pulp raw materials is
Because it varies considerably depending on the length of the pulp raw material and the type of raw material plant, we believe that it is inappropriate to express the amount of chemicals used in terms of concentration.Hereafter, when expressed as a weight% of the absolute dry raw material, hydrogen peroxide is 1 to 1. 20%, preferably 3-10%, alkali hydroxide (sodium hydroxide, potassium hydroxide, etc.) is M ₂ O (M:Na
or K) 6 to 40%, preferably 10 to 25%,
The stabilizer for hydrogen peroxide is 0.5 to 15 if it is water glass.
%, preferably 2 to 8%, and in the case of a chelating agent, 0.1 to 2%, preferably 0.2 to 1%. Examples of chelating agents include EDTA, DTPA,
1-hydroxyethane-1,1-diphosphonic acid etc. can be used, but 1-hydroxyethane-1,1
-Diphosphonic acid is preferred for obtaining unbleached pulp with high whiteness. The amount of quinones is 0.02-1%, preferably 0.05-0.5%. Quinones include anthraquinone, tetrahydroanthraquinone,
Alkyl anthraquinones such as t-butylanthraquinone can be used, and t-butylanthraquinone and amyl anthraquinone are particularly preferred in order to improve the yield. In the FPA cooking method of the present invention, cooking is promoted by forced stirring and mixing at a high concentration and low liquid ratio. That is, non-cellulosic substances such as pectin and lignin on the surface of the raw material to be solubilized are diffused, and the cooking chemicals are constantly in contact with the surface of the raw material in a concentrated state, liberating the thin layer of pulp that is produced and moving it away.
By exposing the insufficiently reacted internal surfaces one after another to the surface, the temperature required for cooking is further accelerated and the PA
This makes it possible to lower the temperature by 50 to 70 degrees Celsius in one fell swoop. In pulping hemp (abaca), as shown in Table 1 below, Table 1 at 90°C under normal pressure using the PA method
It is possible to achieve almost complete pulping in a cooking time that is 1/4 of the cooking time of (C). Among the cooking conditions for FPA method, pressure, temperature and time are 50℃ ~ 50℃ under normal pressure.
Boiling point, 0.5 to 3 hours, preferably 90±10℃, 1
±0.5 hours. As a cooking reactor, a low liquid ratio (2 to 15
A corrosion-resistant stirrer or a high-concentration pump capable of forcibly mixing and stirring a mixture of Containers can be used. At this time, a device equipped with a high concentration pump is convenient for transporting the pulp after cooking to the screening process. The screening device has the function of separating impurities such as lees and dust from the selected pulp, and various sieves such as flat screens with long and narrow pores or round pores and separators such as various liquid cyclones can be used effectively. It is possible. [Effects of the Invention] The scope of application of the present invention is wide, and the effect of streamlining pulp production by use of the present invention is significant. In other words, pulp raw materials include leaf fibers such as abaca and sisal, which are mainly composed of cellulose fibers and contain hemicellulose and a small amount of lignin/or pectin, rods such as bagasse and rice straw, bast and husk such as juute and kenaf. It can be widely applied to various non-wood plant materials such as seed hair of Tonrintar, etc., and shavings. According to the present invention, PA cooking is promoted to such an extent that phase contrast cannot be easily formed using conventional pulping technology, so pulping is possible in about one hour at a temperature below the boiling point under normal pressure, and a white pulp is produced. Unbleached pulp (UFPAP) with extremely high strength can now be obtained at even higher yields than UPAP. As a result, it was found that the basic unit consumption of cooking chemicals could be significantly reduced, which would help conserve resources in the pulp industry. Next, the simplification of processes and equipment accompanying the implementation of the present invention will be described. First, in the present invention, in order to obtain unbleached pulp with high whiteness and extremely high yield, it is sufficient to cook the pulp under normal pressure, so that no high-pressure digester is required. Furthermore, since there is no defibration step after cooking, a refiner, beater, lumpen mill, etc. are not required during pulp production. UFPAP has a high degree of whiteness as an unbleached pulp and is easy to bleach.One-step bleaching with hydrogen peroxide can achieve a high whiteness of 80% or more, so equipment for unbleached or one-step bleached pulp is usually the only option. do not need. In addition, since pulping is performed by short-time cooking at normal pressure, the time required to raise the temperature is short, and there is no need to take time to lower the pressure before blowing, which greatly improves productivity. Additionally, since the cooking temperature is low and there is no need to use a disintegrator, energy savings can be expected. [Example] The present invention will be explained in more detail with reference to Examples below. Example 1 Abaca produced in the Philippines was cut into lengths of 30 to 40 mm, and 1 kg of absolute dry weight and cooking chemicals (NaOH:
150g as Na ₂ O, 70g H ₂ O ₂ , 3g t-butylanthraquinone, 10g chelating agent and water)
The mixture was placed in a 20-volume stainless steel reaction vessel equipped with a stirrer so that the liquid ratio was 9/Kg, and the reaction was carried out with forced mixing and stirring for 60 minutes while maintaining the temperature at 90°C. Immediately after the reaction, the juice was removed and washed with water, and a 12/1000 cut flat screen was used to obtain a total yield of 77.5% (all below are absolute dry harvested materials vs. absolute dry raw materials), of which the selected yield was 72.3.
%, pulp was obtained with a lees ratio of 3.2%. Selected pulp is unbleached, and unbleached pulp has Hunter whiteness.
It was 60.2%. Example 2 Take 1 kg of Okinawa bagasse (length 40 to 70 mm) on an absolute dry basis, and add cooking chemicals (NaOH: 180 g as Na ₂ O, H ₂ O ₂ : 20 g,
Anthraquinone: 3 g, chelating agent: 3 g, and water) were placed in a reaction vessel equipped with a stirrer in the same manner as in Example 1, and the reaction was carried out with forced mixing and stirring for 90 minutes while maintaining the temperature at 92°C. Immediately after the reaction, remove the juice and wash with water.
Using a 6/1000 cut flat screen, pulp was obtained with a total yield of 62.1%, of which a selective yield was 58.2% and a lees ratio was 3.9%. The Hunter whiteness of carefully selected pulp is
It was 58.1%. Example 3 Take 1 kg of absolute dry weight of cotton linters with a fiber length of 2 to 4 mm, and add cooking chemicals (NaOH: 120 g as Na ₂ O, H ₂ O ₃ : 30 g,
Tetrahydroanthraquinone (3 g, chelating agent: 3 g, and water) were placed in a reaction vessel equipped with a stirrer in the same manner as in Example 1, and the mixture was forcibly mixed and stirred for 40 minutes while being maintained at 90° C. to conduct a reaction. Immediately after the reaction, the pulp was dehydrated and washed with water to obtain Kotsuton linter pulp with a Hunter whiteness of 62.8% and a total yield of 84.1%. Example 4 Juute from Bangladesh was cut into lengths of 40 to 60 mm, 1 kg of absolute dry weight was taken, and cooking chemicals (170 g as NaOH:Na ₂ O,
_{H2O2 40g} , t-butylanthraquinone: 2g,
Chelating agent: 3 g and water) were placed in a reaction vessel equipped with a stirrer in the same manner as in Example 1, and the reaction was carried out by forcefully mixing and stirring for 60 minutes while maintaining the temperature at 91°C. Immediately after the reaction, the pulp was dehydrated and washed with water, and a 12/1000 mesh flat screen was used to obtain pulp with a total yield of 68.1%, including a selective yield of 65.9% and a lees ratio of 2.2%. The Hunter whiteness of the selected pulp was 58.2%. The above results are summarized in Table-1. 【table】

Claims (1)

[Claims] 1. A cooking chemical liquid consisting of water, hydrogen peroxide, a hydrogen peroxide generator, an alkali hydroxide, and a hydrogen peroxide stabilizer, or a mixture containing anthraquinones, Cellulose raw material is used as pulp raw material, and both the cooking chemical solution and pulp raw material are supplied to the digester so that the liquid ratio is 2 to 15/Kg, and the mixture is forcibly stirred under normal pressure and at a temperature below the boiling point. One-stage cooking is performed at high speed, and from the resulting digestate, without grinding, beating, or disintegration,
A method for producing unbleached pulp with a high degree of whiteness from a non-wood cellulose raw material, which is characterized in that selected pulp is obtained by simply removing impurities such as lees and dust. 2 At least an agitator and a high concentration pump that have the function of forcibly stirring and mixing a mixture of pulp raw materials and cooking chemicals supplied at a low liquid ratio and heating and/or keeping the mixture at or near the boiling point under normal pressure. Claim 1 comprising a combination of a cooking reaction apparatus comprising one or more corrosion-resistant containers and an apparatus capable of separating and recovering impurities such as lees and dust from the cooked product and selected unbleached pulp. Equipment for implementation.