Method for producing pulp derived from banana pseudostem, and pulp derived from banana pseudostem

Abstract

This method for producing pulp derived from banana pseudostem comprises: a step for cooking the banana pseudostem by immersing the banana pseudostem in an aqueous alkaline solution and heating the immersed banana pseudostem; a step for treating, with oxygen, the banana pseudostem obtained in the preceding step; a step for treating, with sulfuric acid, the banana pseudostem obtained in the preceding step; a step for treating, with ozone, the banana pseudostem obtained in the preceding step; a step for performing a low-temperature alkali treatment (performing CCE) by immersing, in an aqueous alkaline solution, the banana pseudostem obtained in the preceding step; a step for treating, with oxygen and hydrogen peroxide, the banana pseudostem obtained in the preceding step; and a step for treating, with chlorine oxide, the banana pseudostem obtained in the preceding step.

Description

Method for producing pulp derived from banana pseudostem and pulp derived from banana pseudostem

[0001] This invention relates to a method for producing pulp derived from banana pseudostem and to pulp derived from banana pseudostem.

[0002] In recent years, the industrial use of biomass raw materials has attracted attention from a carbon neutrality perspective. In particular, research into the production of pulp from biomass raw materials is being actively pursued.

[0003] Bananas are mainly produced in tropical regions such as Asia, Africa, and Central and South America, with global production exceeding 100 million tons per year. Bananas grow, flower, and bear fruit in a few months to a year, but by then new pseudostem emerges from the base. Since the old pseudostem, which has already produced fruit, will not bear fruit again, the pseudostem is cut down at the base after harvesting and currently becomes a large amount of waste.

[0004] Various attempts have been made to make effective use of banana pseudostems, which ultimately become a large amount of waste, but none have led to commercialization, and currently, only handmade crafts using banana pseudostems as a material are sold.

[0005] As a way to utilize banana pseudostem, a method for producing cellulose fibers from banana pseudostem has been proposed. Patent Document 1 discloses a method for producing cellulose microfibers having an average fiber diameter equivalent to the specific surface area of ​​less than 1000 nm, which includes a step of obtaining refined pulp using banana pseudostem as a raw material, and a beating step of beating the obtained refined pulp to obtain a slurry.

[0006] Japanese Patent Publication No. 2019-194378

[0007] However, the method described in Patent Document 1 failed to produce pulp with a high level of cellulose purity that could be applied to a wide range of pulp products, and also had the drawback of producing pulp with low whiteness.

[0008] This invention has been made in view of the above circumstances, and one aspect of this invention aims to provide a manufacturing method that can obtain pulp with high α-cellulose purity from banana pseudostem.

[0009] Another aspect of the present invention aims to provide pulp with high α-cellulose purity derived from banana pseudostem.

[0010] Furthermore, the description of these problems does not preclude the existence of other problems. Moreover, one aspect of the present invention does not need to solve all of these problems. Furthermore, it is possible to extract other problems from this specification, the drawings, and the claims.

[0011] To achieve the above objective, a method for producing banana pseudostem pulp according to the first aspect of the present invention includes: a step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; a step of oxygenating the banana pseudostem that has undergone the above step; a step of sulfuric acid treating the banana pseudostem that has undergone the above step; a step of ozone treating the banana pseudostem that has undergone the above step; a step of performing low-temperature alkaline treatment (CCE) by immersing the banana pseudostem that has undergone the above step in an alkaline aqueous solution; a step of treating the banana pseudostem that has undergone the above step with oxygen and hydrogen peroxide; and a step of chlorine oxide treating the banana pseudostem that has undergone the above step.

[0012] A method for producing banana pseudostem pulp according to a second aspect of the present invention includes: a step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; a step of oxygenating the banana pseudostem that has undergone the above step; a step of sulfuric acid treating the banana pseudostem that has undergone the above step; a step of ozone treating the banana pseudostem that has undergone the above step; a step of performing low-temperature alkaline treatment (CCE) on the banana pseudostem that has undergone the above step by immersing it in an alkaline aqueous solution; a step of chlorine oxide treating the banana pseudostem that has undergone the above step; and a step of hydrogen peroxide treating the banana pseudostem that has undergone the above step.

[0013] A method for producing banana pseudostem pulp according to a third aspect of the present invention includes: a step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; a step of immersing the banana pseudostem that has undergone the above step in a sulfuric acid and chlorite aqueous solution or hypochlorite aqueous solution; a step of ozone treatment on the banana pseudostem that has undergone the above step; a step of performing cold alkaline treatment (CCE) on the banana pseudostem that has undergone the above step by immersing it in an alkaline aqueous solution; a step of chlorite treatment or hypochlorite treatment on the banana pseudostem that has undergone the above step; and a step of hydrochloric acid treatment on the banana pseudostem that has undergone the above step.

[0014] A method for producing banana pseudostem pulp according to a fourth aspect of the present invention includes: a step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; a step of treating the banana pseudostem that has undergone the above step with chlorite or hypochlorite; a step of performing cold alkaline treatment (CCE) on the banana pseudostem that has undergone the above step by immersing it in an alkaline aqueous solution; a step of immersing the banana pseudostem that has undergone the above step with sulfuric acid and an aqueous solution of chlorite or hypochlorite; a step of performing chlorite or hypochlorite treatment on the banana pseudostem that has undergone the above step; a step of performing hot sulfuric acid treatment on the banana pseudostem that has undergone the above step by immersing it in sulfuric acid and heating it; a step of performing hot hydrogen peroxide treatment on the banana pseudostem that has undergone the above step by immersing it in hydrogen peroxide and an alkaline aqueous solution and heating it; a step of performing chlorite or hypochlorite treatment on the banana pseudostem that has undergone the above step; and a step of performing hydrochloric acid treatment on the banana pseudostem that has undergone the above step.

[0015] A method for producing banana pseudostem pulp according to a fifth aspect of the present invention includes: a step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; a step of oxygenating the banana pseudostem that has undergone the above step; a step of immersing the banana pseudostem that has undergone the above step in an aqueous solution of sulfuric acid and chlorite or an aqueous solution of hypochlorite; a step of ozone treatment the banana pseudostem that has undergone the above step; a step of performing cold alkaline treatment (CCE) by immersing the banana pseudostem that has undergone the above step in an alkaline aqueous solution; and a step of treating the banana pseudostem that has undergone the above step with hydrochloric acid.

[0016] A method for producing banana pseudostem pulp according to a sixth aspect of the present invention includes: a step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; a step of oxygenating the banana pseudostem after the above step; a step of performing cold alkaline treatment (CCE) on the banana pseudostem after the above step by immersing it in an alkaline aqueous solution; a step of immersing the banana pseudostem after the above step in an aqueous solution of sulfuric acid and chlorite or an aqueous solution of hypochlorite; a step of ozone treatment on the banana pseudostem after the above step; and a step of hydrogen peroxide treatment on the banana pseudostem after the above step.

[0017] In a method for producing banana pseudostem pulp according to the first to sixth aspects of the present invention, for example, pulp with an α-cellulose purity of 94.0% or higher is obtained.

[0018] The banana pseudostem-derived pulp according to the seventh aspect of the present invention has an α-cellulose purity of 94.0% or more and an ash content of 1.5 or less.

[0019] For example, the copper value is between 0.1 and 3.6.

[0020] According to one aspect of the present invention, a manufacturing method is provided that makes it possible to obtain pulp with high α-cellulose purity from banana pseudostem.

[0021] According to another aspect of the present invention, it is possible to provide pulp with high α-cellulose purity derived from banana pseudostem.

[0022] (a) A diagram showing a sequence of a pulp manufacturing method according to one aspect of the present invention, and (b) A diagram showing a sequence of a pulp manufacturing method according to another aspect of the present invention. (a) A diagram showing a sequence of a pulp manufacturing method according to one aspect of the present invention, and (b) A diagram showing a sequence of a pulp manufacturing method according to another aspect of the present invention. (a) is an overall photograph of impurities found in the filtrate after washing banana pseudostem with running water, (b) is a magnified photograph of impurities (black points) found in the filtrate after washing banana pseudostem with running water, and (c) is a magnified photograph of impurities (black points) observed in pulp obtained by pulping banana pseudostem and bleaching by a conventional method. A photograph comparing paper made from the pulp of this example (left) and paper made from the pulp of a comparative example (right). A diagram showing a sequence of a pulp manufacturing method according to one aspect of the present invention. A diagram showing a sequence of a pulp manufacturing method according to one aspect of the present invention.

[0023] In this specification, banana (scientific name: Musa spp.) refers to the group of varieties of the Musaceae family, genus Musa, whose fruits are edible. The "banana pseudostem" used in this invention is the part that resembles a tree trunk, with multiple layers of leaf sheaths, and is also called a "false stem." Although banana fruits are used for food, bananas are cut down from the base after the fruit is harvested, so the pseudostem has traditionally been left unprocessed in farmland, or very rarely mixed with bananas that are about to rot and crushed for use as livestock feed. This invention utilizes this banana pseudostem.

[0024] For banana pseudostem, for example, dried and pulverized banana pseudostem may be used. This pulverized banana pseudostem may be passed through a filter (for example, a papermaking screen (manufactured by Aikawa Iron Works Co., Ltd.)) for a predetermined time to remove impurities.

[0025] In this specification, unless otherwise specified, "% (percent)" refers to "mass percent".

[0026] (1. Method for producing pulp derived from banana pseudostem) As illustrated in Figure 6, the method for producing pulp derived from banana pseudostem according to the first aspect of the present invention comprises: a step of digesting the banana pseudostem by immersing it in an aqueous alkaline solution and heating; a step of subjecting the banana pseudostem that has undergone the above step to oxygen treatment; a step of subjecting the banana pseudostem that has undergone the above step to sulfuric acid treatment; a step of subjecting the banana pseudostem that has undergone the above step to ozone treatment; a step of immersing the banana pseudostem that has undergone the above step in an aqueous alkaline solution to perform low-temperature alkali treatment (CCE); a step of subjecting the banana pseudostem that has undergone the above step to oxygen and hydrogen peroxide treatment; and a step of subjecting the banana pseudostem that has undergone the above step to chlorine oxide treatment.

[0027] As illustrated in Figure 5, the method for producing pulp derived from banana pseudostem according to the second aspect of the present invention comprises: a step of digesting the banana pseudostem by immersing it in an aqueous alkaline solution and heating; a step of subjecting the banana pseudostem that has undergone the above step to oxygen treatment; a step of subjecting the banana pseudostem that has undergone the above step to sulfuric acid treatment; a step of subjecting the banana pseudostem that has undergone the above step to ozone treatment; a step of immersing the banana pseudostem that has undergone the above step in an aqueous alkaline solution to perform low-temperature alkali treatment (CCE); a step of subjecting the banana pseudostem that has undergone the above step to chlorine oxide treatment; and a step of subjecting the banana pseudostem that has undergone the above step to hydrogen peroxide treatment.

[0028] As illustrated in Figure 1(a), the method for producing pulp derived from banana pseudostem according to the third aspect of the present invention comprises: a step of digesting the banana pseudostem by immersing it in an aqueous alkaline solution and heating; a step of immersing the banana pseudostem that has undergone the above step in an aqueous solution of sulfuric acid and chlorite or an aqueous hypochlorite solution; a step of subjecting the banana pseudostem that has undergone the above step to ozone treatment; a step of immersing the banana pseudostem that has undergone the above step in an aqueous alkaline solution to perform low-temperature alkali treatment (CCE); a step of subjecting the banana pseudostem that has undergone the above step to chlorite treatment or hypochlorite treatment; and a step of subjecting the banana pseudostem that has undergone the above step to hydrochloric acid treatment.

[0029] According to the fourth aspect of the present invention, the method for producing pulp derived from banana pseudostems, as illustrated in Figure 1(b), comprises a step of digesting the banana pseudostems by immersing them in an alkaline aqueous solution and heating, a step of subjecting the banana pseudostems that have undergone the above step to chlorite treatment or hypochlorite treatment, a step of subjecting the banana pseudostems that have undergone the above step to low-temperature alkaline treatment (CCE) by immersing them in an alkaline aqueous solution, a step of immersing the banana pseudostems that have undergone the above step in sulfuric acid and an aqueous chlorite solution or an aqueous hypochlorite solution, a step of subjecting the banana pseudostems that have undergone the above step to chlorite treatment or hypochlorite treatment, a step of subjecting the banana pseudostems that have undergone the above step to hot sulfuric acid treatment by immersing them in sulfuric acid and heating, a step of subjecting the banana pseudostems that have undergone the above step to hot hydrogen peroxide treatment by immersing them in a hydrogen peroxide solution and an alkaline aqueous solution and heating, a step of subjecting the banana pseudostems that have undergone the above step to chlorite treatment or hypochlorite treatment, and a step of subjecting the banana pseudostems that have undergone the above step to hydrochloric acid treatment.

[0030] According to the fifth aspect of the present invention, the method for producing pulp derived from banana pseudostems, as illustrated in Figure 2(a), comprises a step of digesting the banana pseudostems by immersing them in an alkaline aqueous solution and heating, a step of subjecting the banana pseudostems that have undergone the above step to oxygen treatment, a step of immersing the banana pseudostems that have undergone the above step in sulfuric acid and an aqueous chlorite solution or an aqueous hypochlorite solution, a step of subjecting the banana pseudostems that have undergone the above step to ozone treatment, a step of subjecting the banana pseudostems that have undergone the above step to low-temperature alkaline treatment (CCE) by immersing them in an alkaline aqueous solution, and a step of subjecting the banana pseudostems that have undergone the above step to hydrochloric acid treatment.

[0031] A sixth aspect of the present invention provides a method for producing pulp derived from banana pseudostem, as illustrated in Figure 2(b), comprising: a step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; a step of oxygenating the banana pseudostem after the above step; a step of performing cold alkaline treatment (CCE) on the banana pseudostem after the above step by immersing it in an alkaline aqueous solution; a step of immersing the banana pseudostem after the above step in an aqueous solution of sulfuric acid and chlorite or an aqueous solution of hypochlorite; a step of ozone treatment on the banana pseudostem after the above step; and a step of hydrogen peroxide treatment on the banana pseudostem after the above step.

[0032] The manufacturing method of the present invention can yield pulp from banana pseudostem with, for example, an α-cellulose purity of 94.0% or higher. The α-cellulose purity is preferably 94.1% or higher, more preferably 94.2% or higher, and even more preferably 94.3% or higher. The method for measuring α-cellulose purity will be described later.

[0033] The manufacturing method of the present invention can yield pulp from banana pseudostem with an ash content of, for example, 1.5 or less, preferably 1.4 or less, more preferably 1.35 or less, and even more preferably 1.3 or less. Ash content refers to the non-combustible mineral material that remains after a material has burned completely. In pulp, a lower ash content is preferable because it improves the whiteness. The method for measuring ash content will be described later.

[0034] The manufacturing method of the present invention can yield pulp from banana pseudostem having, for example, a copper value of 0.1 to 3.6, preferably 0.1 to 3.5, more preferably 0.1 to 3.4, and even more preferably 0.1 to 3.3. The copper value is an indicator of the lignin content or bleachability of the pulp. The method for measuring the copper value will be described later.

[0035] In each step of the manufacturing method of the present invention, the banana pseudostem to which various reagents have been added may be referred to as "moist material." "Moist material" refers to a semi-solid substance in which the banana pseudostem has been impregnated with various reagents in each step, and is the state before the various treatments performed in each step.

[0036] This section describes the process of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it. This process is carried out with the aim of dissolving and removing the lignin contained in the banana pseudostem and loosening the fibers. As the alkaline aqueous solution, for example, an aqueous solution of sodium hydroxide (NaOH) is used, and it is added so that, for example, NaOH is 20-40% relative to the banana pseudostem solid content. The heating temperature is, for example, 120-160°C. The heating time is, for example, 20 minutes to 4 hours. In this process, the banana pseudostem is added in an amount that is, for example, 10-35% of the total amount of wet material as banana pseudostem solid content.

[0037] The oxygen treatment process will now be described. This process is carried out with the aim of bleaching the pulp derived from banana pseudostem using oxygen. The oxygen treatment is carried out, for example, by adding a predetermined amount of water, filling with a predetermined amount of oxygen, and treating for, for example, 30 minutes to 6 hours. The oxygen is used at, for example, 2 to 7 atm. The treatment temperature is, for example, 70 to 120°C. In order to improve the bleaching effect, for example, NaOH may be added to adjust the pH, such as NaOH at a concentration of, for example, 0.5 to 5% relative to the banana pseudostem solid content. In addition, for the purpose of protecting the cellulose structure of the pulp (inhibiting decomposition) and improving viscosity and yield, for example, MgSO4 may be added. ４ For example, MgSO4 in relation to the banana pseudostem solids. ４　 It may be added in an amount of 0.1 to 3%. In this process, banana pseudostem is added, for example, in an amount of 5 to 30% of the total amount of wet material as banana pseudostem solids. The oxygen treatment process may be repeated multiple times (for example, two or three times).

[0038] The process of sulfuric acid treatment will now be described. This process is carried out with the aim of bleaching the pulp derived from banana pseudostem with sulfuric acid. The sulfuric acid may be added in an amount of 3 to 7% relative to the banana pseudostem solids, for example. The treatment temperature is, for example, 50 to 100°C. The treatment time is, for example, 1 to 5 hours. In this process, the banana pseudostem is added in an amount of 5 to 20% of the total amount of wet material as banana pseudostem solids.

[0039] The process of ozone treatment will now be described. This process is carried out with the aim of bleaching the pulp derived from banana pseudostem using ozone. Ozone treatment is carried out, for example, by adding a predetermined amount of water to the total amount of wet material so that the banana pseudostem solid content is, for example, 0.05% to 10%, and then filling with ozone so that the ozone content is, for example, 0.5% to 4% relative to the banana pseudostem solid content. Alternatively, a predetermined amount of water is added to the total amount of wet material so that the banana pseudostem solid content is, for example, 5% to 35%, and then filling with ozone so that the ozone content is, for example, 0.5% to 4% relative to the banana pseudostem solid content. The temperature is, for example, 20 to 70°C. The treatment time is, for example, 10 minutes to 6 hours. For the purpose of pH adjustment, sulfuric acid may be added, for example, so that the sulfuric acid content is, for example, 0.01% to 3% relative to the banana pseudostem solid content.

[0040] The following describes a process of performing cold alkaline treatment (CCE) by immersion in an alkaline aqueous solution. This process is carried out with the aim of removing lignin, hemicellulose, and other impurities from pulp derived from banana pseudostem. As the alkaline aqueous solution, for example, an aqueous sodium hydroxide (NaOH) solution is used, and it may be added in an amount of 5 to 150% of the banana pseudostem solid content. The temperature is, for example, 20 to 60°C. The treatment time is, for example, 30 minutes to 5 hours. In this process, banana pseudostem is added in an amount of 5 to 30% of the total amount of wet material as banana pseudostem solid content.

[0041] The process of treating with oxygen and hydrogen peroxide will now be described. This process is carried out with the aim of bleaching the pulp derived from banana pseudostem using oxygen and hydrogen peroxide. For example, hydrogen peroxide solution is added to the banana pseudostem solids in an amount of, for example, 0.05 to 1%, oxygen is added, and the process is carried out for, for example, 30 minutes to 6 hours. The oxygen is used at, for example, 2 to 7 atm. The processing temperature is, for example, 70 to 120°C. To improve the bleaching effect, NaOH may be added to adjust the pH, for example, in an amount of NaOH 0.5 to 5% relative to the banana pseudostem solids. In addition, MgSO4 may be added to protect the cellulose structure of the pulp (inhibit decomposition) and improve viscosity and yield.４ For example, relative to the solid content of banana pseudostem, MgSO ４ may be added in an amount of 0.01 to 3%. Further, for the purpose of suppressing the decomposition of H ２ O ２ and improving the bleaching effect, Na ２ SiO ３ may be added, for example, in an amount such that Na ２ SiO ３ is 0.01 to 3% relative to the solid content of banana pseudostem. In this step, the banana pseudostem is added, for example, in an amount of 5 to 30% as the solid content of banana pseudostem relative to the total amount of the wet material.

[0042] The step of performing chlorine oxide treatment will be described. This step is carried out for the purpose of bleaching the pulp derived from banana pseudostem with chlorine oxide. As the chlorine oxide, for example, ClO ２ is used. For example, a ClO ２ aqueous solution is added, for example, in an amount such that ClO ２ is 0.05 to 5% relative to the solid content of banana pseudostem, and the treatment is performed for, for example, 2 to 6 hours. The treatment temperature is, for example, 50 to 100°C. In this step, the banana pseudostem is added, for example, in an amount of 5 to 30% as the solid content of banana pseudostem relative to the total amount of the wet material.

[0043] The step of performing hydrogen peroxide treatment will be described. The purpose of this step is to bleach the pulp derived from banana pseudostem with hydrogen peroxide. The hydrogen peroxide treatment is performed, for example, by adding hydrogen peroxide water in an amount of, for example, 1 to 10% of hydrogen peroxide relative to the solid content of banana pseudostem, and performing the treatment at a temperature of, for example, 50 to 100°C for, for example, 30 minutes to 5 hours. For the purpose of improving the bleaching effect, for pH adjustment, for example, NaOH may be added in an amount of 0.5 to 3% of NaOH relative to the solid content of banana pseudostem. Further, for the purpose of protecting the cellulose structure of the pulp (suppressing decomposition) and improving the viscosity and yield, for example, MgSO ４ may be added in an amount such that MgSO ４ is 0.1 to 3% relative to the solid content of banana pseudostem. In this step, the banana pseudostem is added, for example, in an amount of 5 to 20% as the solid content of banana pseudostem relative to the total amount of the wet material.

[0044] The process of treating with sulfuric acid and a chlorite or hypochlorite aqueous solution will be described (exemplified as "sulfuric acid / NaClO treatment" in Figures 1 and 2). This process is carried out with the aim of bleaching the pulp derived from banana pseudostem and dissolving and removing fibrous materials other than α-cellulose (such as hemicellulose) in the banana pseudostem by the chlorine gas generated by the reaction of sulfuric acid and chlorite or hypochlorite. Sulfuric acid may be added, for example, in an amount of 2 to 5% relative to the solid content of the banana pseudostem. As for chlorite, for example, sodium chlorite (NaClO) ２ ) and the like are used, and as hypochlorite, for example, sodium hypochlorite (NaClO) is used. For example, an aqueous solution of chlorite or hypochlorite may be added to the banana pseudostem solid content in an amount of 0.5 to 2% of chlorite or hypochlorite. In this process, banana pseudostem is added in an amount of 5 to 30% of the total amount of wet material as banana pseudostem solid content. The temperature is, for example, 60 to 80°C, and the processing time is, for example, 1 to 3 hours.

[0045] The process of treating with chlorite or hypochlorite will be described below. This process is carried out with the aim of bleaching the pulp derived from banana pseudostem with chlorite or hypochlorite. For chlorite and hypochlorite treatment, for example, an aqueous solution of chlorite or hypochlorite may be added to the banana pseudostem solid content in an amount of 1 to 10% of chlorite or hypochlorite, and the treatment is carried out at 60 to 80°C for 0.5 to 2 hours. Examples of chlorites include sodium chlorite (NaClO). ２ ) and the like are used, and as hypochlorite, for example, sodium hypochlorite (NaClO) is used. In this process, banana pseudostem is added in an amount of 5 to 30% of the total amount of wet material as banana pseudostem solids.

[0046] The hydrochloric acid treatment process will now be described. This process is carried out with the aim of bleaching the pulp derived from banana pseudostem using hydrochloric acid. For example, hydrochloric acid is added in an amount of 0.1 to 4% relative to the banana pseudostem solid content, and the treatment is carried out at 60 to 90°C for 1 to 3 hours. In this process, banana pseudostem is added in an amount of 5 to 30% of the total amount of wet material as banana pseudostem solid content.

[0047] The process of performing hot sulfuric acid treatment by immersion in sulfuric acid and heating is described below. This process is carried out for the purpose of bleaching pulp derived from banana pseudostem. Sulfuric acid may be added in an amount of 3-5% relative to the banana pseudostem solid content, for example. The heating temperature is, for example, 90-110°C. The heating time is, for example, 2-4 hours. In this process, banana pseudostem is added in an amount of 5-30% of the total amount of wet material as banana pseudostem solid content.

[0048] The process of performing a hot hydrogen peroxide treatment by heating after adding hydrogen peroxide and an alkaline aqueous solution is described below. This process is performed for the purpose of bleaching pulp derived from banana pseudostem. Hydrogen peroxide solution may be added, for example, in an amount of 3-5% hydrogen peroxide relative to the banana pseudostem solid content, and as an alkaline aqueous solution, for example, an aqueous sodium hydroxide (NaOH) solution may be added in an amount of 2-4% NaOH relative to the banana pseudostem solid content. The heating temperature is, for example, 90-110°C. The heating time is, for example, 1-3 hours. In this process, banana pseudostem is added, for example, in an amount of 5-30% banana pseudostem solid content relative to the total amount of wet material.

[0049] In the manufacturing method of the present invention, the above steps can be carried out in any order, but for example, the hydrochloric acid treatment step may be the final step. By doing so, the ash content (described later) can be effectively reduced, and pulp with higher whiteness can be produced.

[0050] In the manufacturing method of the present invention, after each step, washing may be performed, for example, in running water. Each step may be repeated multiple times (for example, two or three times).

[0051] The manufacturing method of the present invention may further include a step of removing impurities in the pulp during manufacturing using a screen (filtration device) and removing "black points". The inventors have newly discovered that "black points" are included in the impurities removed by the screen. In this specification, "black points" consist of lignin-like substances and polyphenols that are specifically contained in banana pseudostem, and have the property of remaining in the pulp even after the banana pseudostem has been pulped and bleached by conventional methods. If "black points" remain in the pulp, they appear as black spots on the pulp product, and the quality of the pulp product is significantly reduced. Figure 3(b) shows impurities (black points) observed in the filtrate after washing banana pseudostem with running water, and Figure 3(c) shows impurities (black points) observed in the pulp obtained by pulping banana pseudostem and bleaching by conventional methods. As shown in Figure 3(a), many impurities are observed in the filtrate after washing banana pseudostem with running water, and Figure 3(b) is a magnified photograph of one of these impurities. Microscopic observation of the impurities in Figure 3(b) and Figure 3(c) revealed that their shapes were identical. This indicated that these black spot-like impurities are specifically present in banana pseudostems, cannot be removed by conventional bleaching methods, and are "black points" that cause a decline in the quality of pulp products. As for the screen (filtration device), for example, a known papermaking screen (e.g., a flat screen) (e.g., manufactured by Aikawa Iron Works Co., Ltd.) is used.

[0052] (2. Pulp derived from banana pseudostem) The pulp according to the present invention is pulp derived from banana pseudostem, having an α-cellulose purity of 94.0% or more and an ash content of 1.5 or less.

[0053] In the pulp according to the present invention, the α-cellulose purity is 94.0% or higher, preferably 94.1% or higher, more preferably 94.2% or higher, and even more preferably 94.3% or higher. For example, the method described in the Wood Science Experiment Manual (edited by the Japan Wood Research Society) can be used to measure the α-cellulose purity.

[0054] In the pulp according to the present invention, the ash content is 1.5 or less, preferably 1.4 or less, more preferably 1.35 or less, and even more preferably 1.3 or less. Ash content refers to the non-combustible mineral material that remains after a material has burned out, and in pulp, a lower ash content is preferable because it improves the whiteness. For example, the 525°C combustion method according to JIS can be used to measure the ash content.

[0055] In the pulp according to the present invention, for example, the copper number may be 0.1 or more and 3.6 or less, preferably 0.1 or more and 3.5 or less, more preferably 0.1 or more and 3.4 or less, and even more preferably 0.1 or more and 3.3 or less. The copper number is an indicator of the lignin content or bleachability of the pulp. For example, the method for measuring the copper number according to the TAPPI standard can be used.

[0056] The pulp of the present invention is produced from banana pseudostem, for example, by the pulp production method described above. In the pulp according to the present invention, for example, the xylose content may be 1.0% or less, preferably 0.8% or less, and more preferably 0.7% or less. The xylose content is measured by known methods, for example, constituent sugar analysis by ion chromatography. In addition, in the pulp according to the present invention, for example, the mannose content may be 1.0% or less, preferably 0.8% or less, and more preferably 0.6% or less. The mannose content is measured by known methods, for example, constituent sugar analysis by ion chromatography.

[0057] (3. Conclusion) As explained above, the present invention makes it possible to produce high-purity pulp using banana pseudostem, which has conventionally been mostly discarded as an agricultural by-product and whose effective uses have been limited. This makes it possible to produce high-purity pulp derived from biomass raw materials, which is highly desirable from the standpoint of carbon neutrality. The carbon dioxide emissions when producing pulp from banana pseudostem using the method of the present invention have been calculated as "-0.7 kg-CO2e" at the raw material procurement stage, "0.2 kg-CO2e" at the production stage, and a total value of "-0.5 kg-CO2e" (CO2e: CO2 equivalent, a value in carbon dioxide equivalent).

[0058] Conventional banana-derived pulp products, such as banana paper, have extremely low α-cellulose purity, are far from white, and are yellowish-brown in color. Furthermore, they were made by hand, making mass production impossible. However, the manufacturing method of the present invention makes it possible to produce high-quality pulp with high α-cellulose purity and high whiteness on an industrial scale.

[0059] Because the pulp of the present invention has high α-cellulose purity and high whiteness, it can be applied to a wide range of pulp products, such as various paper products, tissue paper, paper napkins, and tea bags.

[0060] By using the manufacturing method of the present invention, it is possible to obtain pulp with an extremely high purity, having an α-cellulose purity of 94.0% or higher. Such high-purity cellulose pulp is expected to be used in high-value-added applications that require high quality, such as dissolving pulp used in the production of cellulose derivatives such as rayon, cellophane, acetate fibers, and carboxymethylcellulose (CMC).

[0061] Furthermore, according to the present invention, impurities in the pulp can be effectively removed. For example, the copper number, which indicates the amount of lignin remaining, can be controlled to a low value of 0.1 to 3.6. In addition, the ash content, which affects the whiteness of the pulp, can be suppressed to 1.5% or less, thereby realizing the production of high-quality pulp.

[0062] Therefore, this invention can develop new uses for banana pseudostem, an underutilized biomass resource, and dramatically increase its added value. This will result in extremely beneficial industrial and social effects, such as reducing environmental impact through waste reduction, ensuring a sustainable raw material supply through the utilization of non-wood resources, and contributing to the agricultural economy of banana-producing regions.

[0063] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples.

[0064] The following pulps were produced from banana pseudostem.

[0065] (Pulp of Example A) Pulp of Example A was prepared as follows. The sequence of steps is shown in Figure 1(a). (1) Treatment of banana pseudostem After drying the banana pseudostem, it was crushed to obtain crushed banana pseudostem (hereinafter referred to as crushed banana). The crushed banana was passed through a papermaking screen (manufactured by Aikawa Iron Works Co., Ltd.) for 15 minutes to remove impurities. (2) Digestion NaOH aqueous solution was added to the crushed banana so that the NaOH content was 35% relative to the banana pseudostem solid content. The banana pseudostem was added in an amount of 17% of the total amount of wet material as banana pseudostem solid content. Digestion was carried out by treating at 140°C for 2 hours. After digestion, it was washed in running water until the pH became neutral. (3) Sulfuric acid / NaClO treatment Sulfuric acid and NaClO aqueous solution were added to the banana pseudostem that had gone through the above steps so that the sulfuric acid content was 3% and the NaClO content was 1% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. Sulfuric acid / NaClO treatment was performed by treating at 70°C for 2 hours. After the sulfuric acid / NaClO treatment, the material was washed in running water until the pH became neutral. (4) Ozone bleaching A predetermined amount of water was added to the banana pseudostem that had undergone the above process so that the banana pseudostem solid content was 1.5% of the total amount of wet material, and ozone was added so that the ozone content was 1.9% of the banana pseudostem solid content. Ozone bleaching was performed by treating for 6 hours. After ozone bleaching, impurities were removed by passing the material through a papermaking screen (manufactured by Aikawa Iron Works Co., Ltd.) while washing with running water. (5) Alkali low-temperature treatment (CCE) NaOH aqueous solution was added to the banana pseudostem that had undergone the above process so that the NaOH content was 9% of the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material, and the mass of the banana pseudostem solid content was 100 g. CCE was performed by treating at 50°C for 4 hours. After CCE, the samples were washed in running water until the pH became neutral. (6) NaClO treatment NaClO aqueous solution was added to the banana pseudostem that had undergone the above process so that the concentration of NaClO was 2% relative to the solid content of the banana pseudostem. The solid content of the banana pseudostem was 10% of the total amount of wet material. NaClO treatment was performed by treating at 70°C for 1 hour. After NaClO treatment, the samples were washed in running water until the pH became neutral.(7) Hydrochloric acid treatment Hydrochloric acid was added to the banana pseudostem that had undergone the above-described process, so that the hydrochloric acid content was 3% relative to the solid content of the banana pseudostem. The solid content of the banana pseudostem was 10% of the total amount of wet material. Hydrochloric acid treatment was carried out by treating at 70°C for 2 hours. After the hydrochloric acid treatment, the material was washed in running water until the pH became neutral to obtain the pulp of Example A.

[0066] (Pulp of Example B) The pulp of Example B was obtained using the same procedure as in Example A, except that the mass of banana pseudostem solids was scaled up to 500 g in (5) of Example A above.

[0067] (Pulp of Example C) Pulp of Example C was prepared as follows. The sequence of steps is shown in Figure 1(b). (1) Treatment of banana pseudostem A banana pulp was obtained in the same manner as in (1) of Example A. (2) Digestion NaOH aqueous solution was added to the banana pulp so that the NaOH content was 35% relative to the banana pseudostem solid content. The banana pseudostem was added in an amount of 17% of the total amount of wet material as banana pseudostem solid content. Digestion was performed by treating at 130°C for 3 hours. After digestion, the material was washed in running water until the pH became neutral. (3) NaClO treatment NaClO aqueous solution was added to the banana pseudostem that had undergone the above steps so that the NaClO content was 8% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. NaClO treatment was performed by treating at 70°C for 1 hour. After NaClO treatment, the material was washed in running water until the pH became neutral. Afterward, impurities were removed using a flat screen. (4) CCE NaOH aqueous solution was added to the banana pseudostem that had undergone the above process so that the NaOH content was 9% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. CCE was performed by treating at 50°C for 4 hours. After CCE, the material was washed in running water until the pH became neutral. (5) Sulfuric acid / NaClO treatment Sulfuric acid and NaClO aqueous solution were added to the banana pseudostem that had undergone the above process so that the sulfuric acid content was 4% and the NaClO content was 1% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. Sulfuric acid / NaClO treatment was performed by treating at 70°C for 2 hours. After sulfuric acid / NaClO treatment, the material was washed in running water until the pH became neutral. (6) NaClO treatment An aqueous NaClO solution was added to the banana pseudostem that had undergone the above-mentioned steps, so that the NaClO content was 2% relative to the solid content of the banana pseudostem. The solid content of the banana pseudostem was 10% of the total amount of wet material. The NaClO treatment was performed by treating at 70°C for 1 hour. After the NaClO treatment, the material was washed in running water until the pH became neutral. (7) Hot sulfuric acid treatment Sulfuric acid was added to the banana pseudostem that had undergone the above-mentioned steps, so that the sulfuric acid content was 4% relative to the solid content of the banana pseudostem. The solid content of the banana pseudostem was 10% of the total amount of wet material. The hot sulfuric acid treatment was performed by treating at 100°C for 3 hours.After the hot sulfuric acid treatment, the banana pseudostem was washed in running water until the pH became neutral. (8) Hot hydrogen peroxide treatment Hydrogen peroxide solution and NaOH aqueous solution were added to the banana pseudostem that had undergone the above-mentioned steps, so that the hydrogen peroxide was 4% and NaOH was 3% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. Hot hydrogen peroxide treatment was performed by treating at 100°C for 2 hours. After the hot hydrogen peroxide treatment, the banana pseudostem was washed in running water until the pH became neutral. (9) NaClO treatment NaClO aqueous solution was added to the banana pseudostem that had undergone the above-mentioned steps, so that the NaClO was 2% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. NaClO treatment was performed by treating at 70°C for 1 hour. After the NaClO treatment, the banana pseudostem was washed in running water until the pH became neutral. (10) Hydrochloric acid treatment Hydrochloric acid was added to the banana pseudostem that had undergone the above-described process, so that the hydrochloric acid content was 3% relative to the solid content of the banana pseudostem. The solid content of the banana pseudostem was 10% of the total amount of wet material. Hydrochloric acid treatment was carried out by treating at 70°C for 2 hours. After the hydrochloric acid treatment, the material was washed in running water until the pH became neutral to obtain the pulp of Example C.

[0068] (Pulp of Example D) Pulp of Example D was prepared as follows. The sequence of steps is shown in Figure 5. (1) Treatment of banana pseudostem A banana pulp was obtained in the same manner as in (1) of Example A. (2) Oxygen treatment (1st time) A predetermined amount of water was added to the banana pulp so that the banana pseudostem solid content was 12% of the total amount of wet material, and NaOH and MgSO were added as auxiliary agents. ４ This is based on the solid content of banana pseudostem, with 2.2% NaOH and MgSO4. ４0.4% was added. Oxygen treatment was performed by filling with 3.9 atm of oxygen and treating at 100°C for 1.5 hours. After oxygen treatment, the samples were washed in running water until the pH became neutral. (3) Oxygen treatment (second time) Oxygen treatment was performed in the same manner as in (2) above. (4) Sulfuric acid treatment Sulfuric acid was added to the banana pseudostem that had undergone the above process so that the sulfuric acid content was 5.3% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% relative to the total amount of wet material. Sulfuric acid treatment was performed by treating at 90°C for 3 hours. After sulfuric acid treatment, the samples were washed in running water until the pH became neutral. (5) Ozone treatment A predetermined amount of water was added to the banana pseudostem that had undergone the above process so that the banana pseudostem solid content was 25.5% relative to the total amount of wet material, and ozone was added so that the ozone content was 1.4% relative to the banana pseudostem solid content. Ozone treatment was performed by treating at 25°C for 24 minutes. Furthermore, sulfuric acid was added as an auxiliary agent, so that the sulfuric acid concentration was 0.83% relative to the banana pseudostem solid content. After ozone treatment, the material was washed with running water until the pH became neutral. (6) CCE NaOH aqueous solution was added to the banana pseudostem that had undergone the above process, so that the NaOH concentration was 133% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. CCE was performed by treating at 25°C for 1 hour. After CCE, the material was washed with running water until the pH became neutral. (7) ClO ２ Processing: The banana pseudostem that has undergone the above-mentioned steps is treated with ClO ２ The aqueous solution is prepared by comparing it to the solid content of the banana pseudostem with ClO ２ It was added to a concentration of 2%. The banana pseudostem solid content was 10% of the total wet material. By immersing at 77°C for 4 hours, ClO ２ Processing was performed. ClO ２ After treatment, the banana pseudostem was washed with running water until the pH became neutral. (8) Hydrogen peroxide treatment Hydrogen peroxide solution and NaOH aqueous solution were added to the banana pseudostem that had undergone the above steps, so that the hydrogen peroxide was 6% and the NaOH was 1.69% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. In addition, MgSO was added as an auxiliary agent. ４ MgSO4 is used in relation to the solid content of banana pseudostem. ４The solution was added to a concentration of 0.3%. Hydrogen peroxide treatment was performed by immersion at 75°C for 2 hours. After the hydrogen peroxide treatment, the pulp was washed twice in running water to obtain the pulp of Example D.

[0069] (Pulp of Example E) Pulp of Example E was prepared as follows. The sequence of steps is shown in Figure 6. (1) Treatment of banana pseudostem A banana pulp was obtained in the same manner as in (1) of Example A. (2) Oxygen treatment (1st time) A predetermined amount of water was added to the banana pulp so that the banana pseudostem solid content was 10% of the total amount of wet material, and NaOH and MgSO were added as auxiliary agents. ４ This is a mixture of 1.5% NaOH and MgSO4 relative to the solid content of banana pseudostem. ４0.5% was added. Oxygen treatment was performed by filling with 5.5 atm of oxygen and treating at 90°C for 1 hour. After oxygen treatment, the samples were washed in running water until the pH became neutral. (3) Oxygen treatment (2nd time) Oxygen treatment was performed in the same manner as in (2) above. (4) Sulfuric acid treatment Sulfuric acid was added to the banana pseudostem that had undergone the above process so that the sulfuric acid content was 4% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% relative to the total amount of wet material. Sulfuric acid treatment was performed by treating at 70°C for 3 hours. After sulfuric acid treatment, the samples were washed in running water until the pH became neutral. (5) Ozone treatment A predetermined amount of water was added to the banana pseudostem that had undergone the above process so that the banana pseudostem solid content was 25% relative to the total amount of wet material, and ozone was added so that the ozone content was 3.1% relative to the banana pseudostem solid content. Ozone treatment was performed by treating at 25°C for 24 minutes. Furthermore, sulfuric acid was added as an auxiliary agent so that the sulfuric acid content was 0.83% relative to the banana pseudostem solid content. After ozone treatment, the material was washed with running water until the pH became neutral. (6) CCE NaOH aqueous solution was added to the banana pseudostem that had undergone the above process so that the NaOH content was 99.8% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. CCE was performed by treating at 25°C for 1 hour. After CCE, the material was washed with running water until the pH became neutral. (7) Oxygen and hydrogen peroxide treatment Hydrogen peroxide solution was added to the banana pseudostem that had undergone the above process so that the hydrogen peroxide content was 0.3% relative to the banana pseudostem solid content. The banana pseudostem solid content was 10% of the total amount of wet material. Furthermore, NaOH and MgSO were added as auxiliary agents. ４ This is based on the solid content of banana pseudostem, with 2.2% NaOH and MgSO4. ４ It was added to a concentration of 0.15%. Oxygen-hydrogen peroxide treatment was performed by filling with 4 atm of oxygen and treating at 100°C for 1.5 hours. After the oxygen-hydrogen peroxide treatment, it was washed once in running water. (8) ClO ２ Processing: The banana pseudostem that has undergone the above-mentioned steps is treated with ClO ２ The aqueous solution is prepared by comparing it to the solid content of the banana pseudostem with ClO ２ It was added to a concentration of 2%. The banana pseudostem solid content was 10% of the total wet material. By immersing at 77°C for 4 hours, ClO２ Processing was performed. ClO ２ After processing, the pulp was washed with running water until the pH became neutral, and the pulp of Example E was obtained.

[0070] (Pulp of Comparative Example 1) (1) Banana pseudostem treatment A banana pulp was obtained in the same manner as in (1) of Example A. (2) Digestion and washing were performed in the same manner as in (2) of Example C. (3) NaClO treatment and washing were performed in the same manner as in (3) of Example C. (4) CCE CCE and washing were performed in the same manner as in (4) of Example C. (5) Sulfuric acid treatment and washing were performed in the same manner as in (5) of Example C. (6) NaClO treatment and washing were performed in the same manner as in (6) of Example C to obtain the pulp of Comparative Example 1.

[0071] (Pulp of Comparative Example 2) (1) Banana pseudostem treatment A banana pulp was obtained in the same manner as in (1) of Example A. (2) Digestion and washing were carried out in the same manner as in (2) of Example C. (3) NaClO treatment and washing were carried out in the same manner as in (3) of Example C. (4) CCE CCE and washing were carried out in the same manner as in (4) of Example C. (5) Sulfuric acid treatment and washing were carried out in the same manner as in (5) of Example C. (6) NaClO treatment and washing were carried out in the same manner as in (6) of Example C. (7) Hydrochloric acid treatment and washing were carried out in the same manner as in (10) of Example C to obtain the pulp of Comparative Example 2.

[0072] (Measurement of α-cellulose purity) The α-cellulose purity of the pulps from Examples A to E and Comparative Examples 1 to 2 was measured according to the method described in the Wood Science Experiment Manual (edited by the Japan Wood Research Society).

[0073] (Ash content measurement) The ash content of the pulp from Examples A to E and Comparative Examples 1 to 2 was measured by the 525°C combustion method according to JIS standards.

[0074] (Measurement of Copper Value) The copper values ​​of the pulps from Examples A to E and Comparative Examples 1 to 2 were measured according to the copper value measurement method specified in the TAPPI standard.

[0075] (Results) Table 1 shows the measured values ​​of the pulps from Examples A to E and Comparative Examples 1 to 2. Regarding α-cellulose purity, Comparative Examples 1 to 2 showed less than 94%, while Examples A to E showed a high α-cellulose purity of 94% or more. Regarding ash content, Comparative Example 1 showed a high value of 3.2 and Comparative Example 2 showed a high value of 1.54, while Example A showed a low value of 1.27, Example B showed a low value of 1.13, Example C showed a low value of 0.27, Example D showed a low value of 0.86. Regarding the copper number, Comparative Example 1 showed a high value of 3.9 and Comparative Example 2 showed a high value of 3.7, while Example A showed a low value of 3.2, Example B showed a low value of 3.3, Example C showed a low value of 2.1, and Example D showed a low value of less than 1. Furthermore, comparing the appearance of each pulp, the pulp of Comparative Example 1 was yellow, the pulp of Comparative Example 2 was beige, while the pulps of Examples A to E were white.

[0076]

[0077] The appearance of paper made from the pulp of Example A and paper made from Comparative Example 3 (pulp made only through pulping and NaClO treatment as in Example A) were compared. Photographs of both are shown in Figure 4. In Figure 4, the left side shows the paper made from the pulp of Example A, and the right side shows the paper made from Comparative Example 3. Visually, the paper made from the pulp of Example A (left side) was confirmed to have a higher degree of whiteness compared to the paper made from Comparative Example 3 (right side).

[0078] Based on the above, it has been demonstrated that the method of this embodiment can yield high-quality pulp with high α-cellulose purity and high whiteness from banana pseudostem.

[0079] Furthermore, the present invention can be implemented in various forms and modified without departing from the broad spirit and scope of the invention. The embodiments described above are for illustrative purposes only and do not limit the scope of the invention. In other words, the scope of the invention is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and equivalent meanings of the invention are considered to be within the scope of the present invention.

[0080] This invention is based on Japanese Patent Application No. 2025-068743, filed on 18 April 2025. The entire specification, claims, and drawings of Japanese Patent Application No. 2025-068743 are incorporated herein by reference.

Claims

1. A method for producing banana pseudostem pulp, comprising:

1. A step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; 2. A step of oxygenating the banana pseudostem that has undergone the above step; 3. A step of sulfuric acid treating the banana pseudostem that has undergone the above step; 4. An ozone treatment of the banana pseudostem that has undergone the above step; 5. A step of performing cold alkaline treatment (CCE) on the banana pseudostem that has undergone the above step by immersing it in an alkaline aqueous solution; 6. A step of oxygenating and hydrogen peroxide treating the banana pseudostem that has undergone the above step; and 7. A step of chlorine oxide treating the banana pseudostem that has undergone the above step.

2. A method for producing banana pseudostem pulp, comprising:

2. A step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; 3. A step of oxygenating the banana pseudostem that has undergone the above step; 4. A step of sulfuric acid treatment the banana pseudostem that has undergone the above step; 5. An ozone treatment the banana pseudostem that has undergone the above step; 6. A step of performing cold alkaline treatment (CCE) on the banana pseudostem that has undergone the above step by immersing it in an alkaline aqueous solution; 7. A step of chlorine oxide treatment the banana pseudostem that has undergone the above step; and 8. A step of hydrogen peroxide treatment the banana pseudostem that has undergone the above step.

3. A method for producing pulp derived from banana pseudostem, comprising:

3. A step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; 4. A step of immersing the banana pseudostem that has undergone the above step in an aqueous solution of sulfuric acid and chlorite or hypochlorite; 5. A step of ozone treatment on the banana pseudostem that has undergone the above step; 6. A step of performing cold alkaline treatment (CCE) on the banana pseudostem that has undergone the above step by immersing it in an alkaline aqueous solution; 7. A step of chlorite treatment or hypochlorite treatment on the banana pseudostem that has undergone the above step; and 8. A step of hydrochloric acid treatment on the banana pseudostem that has undergone the above step.

4. A method for producing banana pseudostem pulp, comprising:

4. A step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; 5. A step of treating the banana pseudostem that has undergone the above step with chlorite or hypochlorite; 6. A step of performing cold alkaline treatment (CCE) on the banana pseudostem that has undergone the above step by immersing it in an alkaline aqueous solution; 7. A step of immersing the banana pseudostem that has undergone the above step with sulfuric acid and an aqueous solution of chlorite or hypochlorite; 8. A step of performing hot sulfuric acid treatment on the banana pseudostem that has undergone the above step by immersing it in sulfuric acid and heating it; 9. A step of performing hot hydrogen peroxide treatment on the banana pseudostem that has undergone the above step by immersing it in hydrogen peroxide and an alkaline aqueous solution and heating it; 10. A step of performing chlorite or hypochlorite treatment on the banana pseudostem that has undergone the above step; and 11. A step of performing hydrochloric acid treatment on the banana pseudostem that has undergone the above step.

5. A method for producing pulp derived from banana pseudostem, comprising:

1. immersing the banana pseudostem in an alkaline aqueous solution and heating it to pulp it; 2. oxygenating the banana pseudostem that has undergone the above step; 3. immersing the banana pseudostem that has undergone the above step in a sulfuric acid and chlorite aqueous solution or a hypochlorite aqueous solution; 4. ozoneting the banana pseudostem that has undergone the above step; 5. immersing the banana pseudostem that has undergone the above step in an alkaline aqueous solution to perform cold alkaline treatment (CCE); and 6. hydrochloric acid treating the banana pseudostem that has undergone the above step.

6. A method for producing pulp derived from banana pseudostem, comprising:

6. A step of pulping banana pseudostem by immersing it in an alkaline aqueous solution and heating it; 7. A step of oxygenating the banana pseudostem that has undergone the above step; 8. A step of performing cold alkaline treatment (CCE) on the banana pseudostem that has undergone the above step by immersing it in an alkaline aqueous solution; 9. A step of immersing the banana pseudostem that has undergone the above step in an aqueous solution of sulfuric acid and chlorite or an aqueous solution of hypochlorite; 10. A step of ozone treatment on the banana pseudostem that has undergone the above step; and 11. A step of hydrogen peroxide treatment on the banana pseudostem that has undergone the above step.

7. The manufacturing method according to any one of claims 1 to 6, characterized in that it obtains pulp with an α-cellulose purity of 94.0% or higher.

8. Pulp derived from banana pseudostem, with an α-cellulose purity of 94.0% or higher and an ash content of 1.5% or less.

9. The pulp according to claim 8, wherein the copper number is 0.1 or more and 3.6 or less.

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