Pulp production method, paper production method and compressed material used in pulp production

Abstract

Provided is a pulp production method which is less likely to lead to a decrease in productivity even when a plant of the family Palmaceae is used. A pulp production method includes defibrating a wood material by a digesting treatment using an aqueous alkali solution. The wood material comprises a compressed material obtained by compressing a crushed material of a plant of the family Palmaceae. The compressed material has a specific gravity greater than or equal to 0.35 and less than or equal to 1.30 and a water content of less than or equal to 25% by mass. The compressed material preferably has a surface area of less than or equal to 15 cm2. The crushed material preferably contains a crushed material having a length of 0.6 mm or more and 40.0 mm or less and an outer diameter of 0.08 mm or more and 1.5 mm or less. The comminuted material having this size preferably has a content higher than or equal to 70% by mass based on the total mass of the comminuted material.

Description

Technical Field

[0001] The present disclosure relates to a method for producing pulp, a method for producing paper, and a compression material used in pulp production. More specifically, the present disclosure relates to a pulp production method for producing pulp from Plamae plants, a paper production method for producing paper from Plamae plants, and a compression material used in pulp production, the compression material being produced from Plamae plants. Background Art

[0002] Patent Document 1 describes producing pulp from petiolate parts of Plamae plants. Specifically, a pulp bleaching method is described, which includes: cooking oil palm petiolate parts by Kraft cooking to achieve a Kappa number in the range of greater than or equal to 18 and less than or equal to 40; then subjecting the oil palm petiolate parts to oxygen delignification; and further treating the oil palm petiolate parts in a multi-stage bleaching step including a hydrogen peroxide treatment step.

[0003] Patent Document 2 describes producing pulp from the trunks of Plamae plants. Specifically, a pulp production method including at least an oxidation step and a cooking step is described. The oxidation step includes allowing a chemical solution containing nitric acid to penetrate the raw material at atmospheric pressure to obtain a porous raw material. The cooking step includes: allowing a chemical solution containing caustic soda to penetrate the porous raw material at atmospheric pressure; and bringing the raw materials into contact with each other by eddy currents to separate the fibers from lignin in the porous raw material, thereby defibrating the fiber bundles.

[0004] List of Cited References

[0005] Patent Documents

[0006] Patent Document 1: JP H08-311789A

[0007] Patent Document 2: WO2010 / 147118A1 Summary of the Invention

[0008] Plamae plants have a high water content and are prone to decay, and thus have poor storage properties. In addition, Plamae plants have a low apparent specific gravity and low transport efficiency. Therefore, there is a problem that when producing papermaking pulp from Plamae plants using the methods described in Patent Document 1 and Patent Document 2, the productivity is more likely to decrease.

[0009] An object of the present disclosure is to provide a pulp production method that is less likely to cause a reduction in productivity even when using palm plants. In addition, an object of the present disclosure is to provide: a paper production method for producing paper from pulp produced by the pulp production method; and a compressed material used in pulp production, which is used in the pulp production method.

[0010] A pulp production method according to an aspect of the present disclosure is a pulp production method that includes defibrating woody materials by a cooking treatment using an aqueous alkali solution. The woody materials include a compressed material obtained by compressing crushed materials of palm plants. The compressed material has a specific gravity of greater than or equal to 0.35 and less than or equal to 1.30 and a water content of less than or equal to 25% by mass.

[0011] A paper production method according to an aspect of the present disclosure includes: a pulping step of producing pulp by the pulp production method; and a step of obtaining paper by skimming and drying the pulp.

[0012] A compressed material used in pulp production according to an aspect of the present disclosure is a compressed material obtained by compressing crushed materials of palm plants. The compressed material used in pulp production has a specific gravity of greater than or equal to 0.35 and less than or equal to 1.30 and a water content of less than or equal to 25% by mass. Detailed Description

[0013] (Example)

[0014] (1) Overview

[0015] The pulp production method according to the present embodiment is a method that includes defibrating woody materials by a cooking treatment using an aqueous alkali solution. The woody materials include a compressed material obtained by compressing crushed materials of palm plants. The compressed material has a specific gravity of greater than or equal to 0.35 and less than or equal to 1.30. In addition, the water content of the compressed material is less than or equal to 25% by mass.

[0016] In the present embodiment, the specific gravity of the compressed material obtained by compressing the crushed materials of palm plants is greater than or equal to 0.35 and less than or equal to 1.30. Therefore, the bulk density of palm plants can be increased, thereby improving the transportation efficiency of palm plants. In addition, in the present embodiment, the water content of the compressed material obtained by compressing the crushed materials of palm plants is less than or equal to 25% by mass. Therefore, decay is less likely to occur and the storage performance is good. Therefore, even when using palm plants, the pulp production method of the present embodiment is less likely to cause a reduction in productivity.

[0017] (2) Details

[0018] (Compressed Material Used in Pulp Production)

[0019] The compressed material used in the pulp production according to this embodiment is a compressed material of dried sheets of ground material of palm family plants. That is, palm cut pieces and / or crushed pieces as the ground material of palm family plants are used as raw materials, and these sheets are dried and then compressed together to obtain a compressed material (compressed biomass) for use in the production of pulp including renewable biological resources (palm family plants). Compared with the case where the ground material of palm family plants is not compressed, the transportability of the compressed material used in pulp production is improved and the productivity is improved. In addition, since dried ground material is used, the development of rot can be prevented, the yield of the material can be increased, and the productivity can be increased.

[0020] The type of palm family plant that causes social problems is the oil palm, but the type of palm family plant used in the compressed material for pulp production can be, for example, the doub palm, coconut palm, date palm, sago palm, palm and chusan palm, and is not limited to a specific type. In addition, the available parts are, for example, but not limited to, the trunk part, leaf part, fruit part, bunch portions, and seed part.

[0021] The palm family plant is ground, dried, and then compressed. Note that grinding and drying can be carried out in any order, or grinding and drying can be carried out simultaneously. In addition, the method for grinding the palm family plant can be, for example, but not particularly limited to, performed by using a chipper. In addition, it is preferable to dry the ground material to obtain a water content of 25% by mass or less to prevent the development of rot.

[0022] The ground material of palm family plants is an aggregate of fibrous substances (including powdery substances) obtained by grinding the available parts of palm family plants. The ground material of palm family plants preferably includes the vascular tissue of palm family plants. The vascular tissue of palm family plants is the tissue that transports water and nutrients required for the growth of palm family plants and includes the xylem and phloem. The xylem is the conduction path of water and nutrients absorbed by the roots and includes vessels and tracheids. The phloem is the conduction path of nutrients produced at the leaves and includes sieve tubes.

[0023] The comminuted material of the palm family plant preferably contains comminuted material having a predetermined size. The comminuted material is preferably comminuted material having a length greater than or equal to 0.6 mm and less than or equal to 40.0 mm and an outer diameter greater than or equal to 0.08 mm and less than or equal to 1.5 mm (hereinafter, the comminuted material within this range is referred to as "comminuted material of advantageous size"). When the length of the comminuted material is shorter than 0.6 mm or the outer diameter of the comminuted material is less than 0.08 mm, the vascular tissue of the palm family plant included in the comminuted material is too fine. Therefore, the average length of the pulp to be obtained is short, and the paper tends to have reduced strength. In addition, when the length of the comminuted material is greater than 40.0 mm or the outer diameter of the comminuted material is greater than 1.5 mm, the shape of the pulp contained in the paper is too rough. Therefore, the paper is more likely to have reduced surface smoothness. That is, when the length of the comminuted material is greater than or equal to 0.6 mm and less than or equal to 40.0 mm, and the outer diameter of the comminuted material is greater than or equal to 0.08 mm and less than or equal to 1.5 mm, high-quality pulp can be obtained.

[0024] The length of the comminuted material is more preferably in the range of greater than or equal to 5.0 mm and less than or equal to 40.0 mm, and the outer diameter of the comminuted material is more preferably in the range of greater than or equal to 0.3 mm and less than or equal to 1.5 mm. In this case, the strength of the paper is less likely to decrease, and the surface smoothness of the paper is less likely to decrease. Note that the length and outer diameter of the comminuted material can be determined by measuring the length and outer diameter by photographing or observing a predetermined amount of the comminuted material of the palm family plant using a magnifying viewer.

[0025] The content of the comminuted material of advantageous size is preferably higher than or equal to 70% by mass based on the total mass of the comminuted material of the palm family plant. When the mass ratio is lower than 70%, the pulp (fiber component) having a length that contributes to the expression of the strength of the paper decreases, and the paper tends to have reduced strength. In addition, the ratio of the parenchymous tissue of the palm family plant, which is the main component of the fine particles, to the comminuted material of the palm family plant increases, and the amount of the aqueous alkali solution used in the cooking treatment tends to increase, which may reduce the pulp productivity. The content of the comminuted material of advantageous size is more preferably higher than or equal to 80% by mass based on the total mass of the comminuted material of the palm family plant, and most preferably 100% by mass.

[0026] The pulverized material of the palm family plant is preferably a pulverized material in which the amount of the parenchyma tissue of the palm family plant is reduced by classification performed after pulverization of the palm family plant. That is, the pulverized material of the palm family plant includes small pulverized materials and large pulverized materials. The small pulverized materials include the parenchyma tissue of the palm family plant as the main component, and the large pulverized materials include the vascular tissue of the palm family plant as the main component, and the amount of the small pulverized materials has been preferably reduced. The parenchyma tissue of the palm family plant is a tissue including parenchyma cells of the palm family plant. The parenchyma tissue of the palm family plant includes assimilation tissue, secretory tissue, storage tissue, etc., and has physiological activities such as synthesis, decomposition, and storage.

[0027] When the pulverized material of the palm family plant includes a large amount of the parenchyma tissue of the palm family plant, an increased amount of an aqueous alkali solution tends to be used, and thus, stable production of pulp may become difficult. Therefore, in the present embodiment, the amount of the parenchyma tissue of the palm family plant is reduced to obtain a pulverized material of the palm family plant with a reduced content of the parenchyma tissue of the palm family plant. The method for reducing the amount of the parenchyma tissue of the palm family plant may employ a method of removing small-sized pulverized materials by classification. Examples of classification include, but are not limited to, screening methods, air classification methods, and bathing methods.

[0028] The pulverized material of the palm family plant is preferably a pulverized material in which the amount of sugar has been reduced by washing with water after pulverization of the palm family plant. In this case, unsatisfactory drying in the papermaking step can be reduced. As used herein, saccharides are monosaccharides, disaccharides and polysaccharides (including oligosaccharides). Examples of monosaccharides include fructose, ribose, arabinose, rhamnose, xylulose and deoxyribose. Examples of disaccharides include sucrose, maltose, trehalose, turanose, lactulose, maltulose, palatinose (also known as isomaltulose), gentiobiulose, melibiulose, galactosucrose, rutinulose and planteobiose. Examples of polysaccharides include starch, agarose, alginic acid, glucomannan, inulin, chitin, chitosan, hyaluronic acid, glycogen and cellulose. Examples of oligosaccharides include fructo-oligosaccharide, galacto-oligosaccharide, mannan-oligosaccharide and stachyose. In addition, the amount of sugar is preferably reduced by 50% or more compared to the amount of sugar before washing with water. Note that in the washing with water of the palm family plant, it is preferable that the amount of ash content is also reduced, which can reduce the occurrence of process problems due to the ash content in the cooking step described later.

[0029] The compressed material used in the pulp production of the present embodiment is obtained by compressing and coalescing the dried sheets of the comminuted material. That is, the compressed material used in the pulp production of the present embodiment is a compressed material including dried sheets of comminuted material of palm family plants (biomass), and the sheets of the comminuted material are agglomerated. The shape of the compressed material used in the pulp production is, for example, but not particularly limited to, a granular shape, a tablet shape, a briquette shape, a block shape, or a plate shape. The compressed material having a granular shape can be obtained by using a known granulator (such as a flat die granulator or a ring die granulator). The compressed material having a tablet shape can be obtained by using a known tablet molding machine with a die having a hollow portion corresponding to the shape of the compressed material. The compressed material having a briquette shape can be obtained by using a known briquetting machine (such as a molding machine), using a die having, for example, a front opening and a rear opening, where the comminuted material is put into the die in a state where the already formed compressed material is disposed at one of the front opening and the rear opening, and the comminuted material is compressed by pressing from the side of the other of the front opening and the rear opening, and the compressed material moves forward. The compressed material having a block shape can be obtained by using a known volume reducing machine, such as a single-axis volume reducing machine, where the comminuted material is put into a frame that is not airtight closed on one side, and the comminuted material is compressed by pressing from the non-airtight closed side, or a three-axis volume reducing machine configured to perform compression in three directions. The compressed material having a plate shape can be obtained by stacking the sheets of the comminuted material on each other to form a mat; and compressing the mat in the thickness direction. Note that when compressed, the sheets of the comminuted material coalesce by the compression force without using an adhesive, but an adhesive can be used to an extent that does not interfere with the fibrillation of the woody material.

[0030] The compressed material used in the pulp production of the present embodiment preferably has a surface area of less than or equal to 15 cm 2 . In this case, when the woody material including the compressed material used in the pulp production is defibrated by a cooking treatment, the chemical solution in the cooking treatment easily penetrates the compressed material used in the pulp production, and further promotes the defibration of the woody material. Note that the lower limit of the surface area of the compressed material used in the pulp production is not set to a specific value, but for ease of handling, it is preferably greater than 1 cm 2 .

[0031] The compression material used in the pulp production of this embodiment preferably has a specific gravity in the range of greater than or equal to 0.35 and less than or equal to 1.30. When the specific gravity of the compression material used in pulp production is less than 0.35, the compression material used in pulp production has reduced mechanical durability and is more likely to break or fracture during transportation. When the specific gravity of the compression material used in pulp production is greater than 1.30, the chemical solution (e.g., aqueous alkali solution) during cooking is less likely to penetrate the compression material, and defibration may not be satisfactory. In addition, even when defibration is completed, the fiber tissue contained in the crushed material of the palm family plants may be damaged by compression, thereby increasing the number of fines, and the resulting paper often has reduced strength properties. The specific gravity of the biomass compression material is more preferably in the range of greater than or equal to 0.40 and less than or equal to 1.30, and when the specific gravity is less than 0.40, the bulk density is high, and the volume thus results in reduced transportation efficiency, thereby increasing the number of round trips for transportation. Therefore, the specific gravity of the compressed biomass is more preferably in the range of greater than or equal to 0.40 and less than or equal to 1.30.

[0032] The water content of the compression material used in the pulp production of this embodiment is preferably less than or equal to 25% by mass, and more preferably less than or equal to 20% by mass. When the water content is higher than 25% by mass, the compression material used in pulp production is more likely to have deteriorated shape retention properties, and at the same time is more likely to be susceptible to fungal growth and more likely to rot, and thus is more likely to have deteriorated storage properties. Note that the lower limit of the water content of the compression material used in pulp production is not set to a specific value, but is at least greater than or equal to 0% by mass.

[0033] Therefore, when the specific gravity is in the range of greater than or equal to 0.35 and less than or equal to 1.30, the compression material used in the pulp production of this embodiment has improved storage performance and mechanical durability, and the fiber tissue of the palm family plants is less likely to be damaged by compression. In addition, when the water content is less than or equal to 25% by mass, the compression material used in the pulp production of this embodiment is less likely to be susceptible to fungal growth and less likely to rot, and thus has improved storage properties. Note that the "mechanical durability" used in this disclosure refers to shape retention and refers to the property of being less likely to break or fracture during storage.

[0034] <Pulp production method>

[0035] The pulp production method according to this embodiment is a pulp production method that includes defibrating woody materials including compressed materials used in pulp production by cooking treatment using an aqueous alkali solution. The pulp production method of this embodiment uses compressed materials for pulp production, and thus can easily produce pulp with a constant quality even when using palm family plants with a low bulk density. Note that as the woody materials, only the compressed materials used in pulp production can be used, or the crushed materials of Nanhai wood and / or coniferous trees that have been used for papermaking and the compressed materials used in pulp production can be used together.

[0036] The alkaline aqueous solution is an aqueous solution containing alkaline components such as sodium hydroxide, sodium sulfide, and mixtures thereof. The concentration of the alkaline component is not limited to a specific concentration, but is preferably higher than or equal to 0.5% by mass and lower than or equal to 10% by mass.

[0037] The cooking treatment is a treatment including the following steps: treating the woody materials with a high-temperature alkaline aqueous solution, and separating the lignin contained in the woody materials by dissolution to achieve defibration into wood fibers (mainly the vascular tissue of palm family plants). The conditions for cooking are but not particularly limited to: being able to cause a reaction by using an alkaline aqueous solution at a temperature of 90°C to 180°C in a digester or autoclave.

[0038] After defibration, drying is performed as needed. Drying is a process of reducing the water content of the wood fibers obtained by defibration. Drying can be performed by supplying hot air to the wood fibers obtained by defibration. The water content of the wood fibers after drying is, but not preferably limited to, for example, lower than or equal to 20% by mass based on the total mass of the wood fibers after absolute drying.

[0039] The wood fibers obtained thereby can be used as pulp.

[0040] <Papermaking method>

[0041] The paper production method according to this embodiment includes a pulping step and a step of obtaining paper. The pulping step is a step of producing pulp by a pulp production method. The step of obtaining paper is skimming and drying the pulp produced in the pulping step. Skimming can be performed by using, for example, a Fourdrinier paper machine, a cylinder paper machine, or a sheet former. Drying is drying the pulp using a dryer after skimming to obtain a predetermined water content.

[0042] (Summary)

[0043] The first aspect is a pulp production method that includes defibrating woody materials through a cooking treatment using an aqueous alkali solution. The woody materials include compressed materials obtained by compressing crushed materials of palm plants. The compressed materials have a specific gravity greater than or equal to 0.35 and less than or equal to 1.30 and a water content of less than or equal to 25% by mass.

[0044] In this regard, the storage performance of palm plants is good, and the transportation efficiency of palm plants is also high. Therefore, there is an advantage that the pulp production rate is unlikely to decrease even when using palm plants.

[0045] The second aspect is the pulp production method according to the first aspect, wherein the compressed material has a surface area of less than or equal to 15 cm 2 The surface area.

[0046] This aspect promotes the penetration of chemical solutions (e.g., aqueous alkali solutions) into the compressed material during the cooking treatment and promotes defibration.

[0047] The third aspect is the pulp production method according to the first aspect or the second aspect, wherein the crushed material includes crushed material having a length dimension longer than or equal to 0.6 mm and shorter than or equal to 40.0 mm and an outer diameter greater than or equal to 0.08 mm and less than or equal to 1.5 mm. The crushed material having this size has a content rate of higher than or equal to 70% by mass based on the total mass of the crushed material.

[0048] In this regard, the pulp in powder form is reduced, and the strength of the paper is unlikely to decrease.

[0049] The fourth aspect is the pulp production method according to any one of the first aspect to the third aspect, wherein the crushed material is a crushed material in which the amount of parenchyma has been reduced by classification after crushing the palm plants.

[0050] In this regard, the parenchyma is removed, which can reduce the amount of aqueous alkali solution used, thereby improving the pulp production rate.

[0051] The fifth aspect is the pulp production method according to any one of the first aspect to the fourth aspect, wherein the crushed material is a crushed material in which the amount of sugar has been reduced by washing after crushing the palm plants.

[0052] Through this aspect, pulp with reduced sugar is obtained. Therefore, unsatisfactory drying in the papermaking step can be reduced.

[0053] The sixth aspect is a paper production method that includes a pulping step of producing pulp through a pulp production method and a step of obtaining paper by skimming and drying the pulp.

[0054] This aspect has the advantage that it can effectively produce pulp and also improve the productivity of paper.

[0055] The seventh aspect is a compressed material used in pulp production, and the compressed material is obtained by compressing the crushed material of palm plants. The compressed material used in pulp production has a specific gravity greater than or equal to 0.35 and less than or equal to 1.30 and a water content less than or equal to 25% by mass.

[0056] In this regard, the storage performance of palm plants is good, and the transportation efficiency of palm plants is also high. Therefore, it has the advantage that the productivity of pulp is unlikely to decrease even when palm plants are used. Examples:

[0057] (Example 1)

[0058] As a raw material for pulp for biomass paper, oil palm trunk (OPT) is extracted from oil palm and put into a shredder to obtain crushed biomass with a size greater than or equal to 20 mm and less than or equal to 40 mm.

[0059] Then, foreign substances are removed by using a foreign substance remover, and the crushed biomass is washed with water, dehydrated, and then dried by passing it through a jet dryer to obtain a predetermined water content.

[0060] Thereafter, the crushed biomass is classified through a 10-mesh sieve and then through a 200-mesh sieve to reduce the ratio of parenchyma cells, thereby obtaining crushed biomass (crushed material of palm plants) with an average length of 25 mm, an average outer diameter of 1.0 mm, and a content rate of crushed materials with favorable dimensions of 80%. Note that the crushed material has a reduced sugar amount by water washing.

[0061] The crushed material is used as a raw material and compressed into cylindrical pellets with a diameter of 10 mm and a length of 50 mm each by using a granulator to obtain compressed biomass (compressed material used in pulp production) with a specific gravity of 0.95 and a water content of 12%.

[0062] The compressed material and a 5% sodium hydroxide aqueous solution are put into an autoclave so that the solution ratio is 1:4 (for 1 mass of the compressed material, the mass of the 5% sodium hydroxide aqueous solution is 4).

[0063] Next, increase the temperature of the autoclave by heating, and maintain the state of the autoclave at 170 °C and 0.8 MPa for 2 hours, then release the pressure in the autoclave to return the pressure to normal pressure. Thereafter, take out the contents of the autoclave by washing with water, filter through a polyester bag with a mesh size of about 100 μm, and dry the contents to obtain pulp.

[0064] (Example 2)

[0065] As the raw material for the pulp, OPT is used, and a crushed material with an average length of 30 mm, an average outer diameter of 1.2 mm, and a content rate of crushed material with favorable dimensions of 85% is prepared in steps similar to those in Example 1.

[0066] Thereafter, in order to compress the crushed material, a briquetter is used to compress the crushed material into a briquette shape with a diameter of 50 mm and a length of 40 mm, thereby obtaining a compressed biomass (compressed material used in pulp production) with a specific gravity of 1.00 and a water content of 11%. Except for using such compressed biomass, pulp is obtained in a manner similar to Example 1.

[0067] (Example 3)

[0068] As the raw material for the pulp, OPT is used, and a crushed material with an average length of 20 mm, an average outer diameter of 1.5 mm, and a content rate of crushed material with favorable dimensions of 90% is prepared in steps similar to those in Example 1.

[0069] Thereafter, in order to compress the crushed material, a three-axis volume reduction machine is used to produce a compressed material with a 40 mm square block shape, thereby obtaining a compressed biomass (compressed material used in pulp production) with a specific gravity of 0.90 and a water content of 13%. Except for using such compressed biomass, pulp is obtained in a manner similar to Example 1.

[0070] (Example 4)

[0071] As the raw material for the pulp, the trunk part of coconut palms is used, and a crushed material with an average length of 23 mm, an average outer diameter of 1.0 mm, and a content rate of crushed material with favorable dimensions of 80% is prepared in steps similar to those in Example 1.

[0072] Thereafter, in order to compress the crushed material, a granulator is used to produce a compressed material with a cylindrical pellet shape with a diameter of 10 mm and a length of 50 mm, thereby obtaining a compressed biomass (compressed material used in pulp production) with a specific gravity of 1.05 and a water content of 12%. Except for using such compressed biomass, pulp is obtained in a manner similar to Example 1.

[0073] (Example 5)

[0074] As the raw material of the pulp, OPT is used, and in steps similar to those in Example 1, a pulverized material with an average length of 20 mm, an average outer diameter of 1.0 mm, and a content rate of the pulverized material with favorable dimensions of 85% is prepared.

[0075] Thereafter, in order to compress the pulverized material, a granulator is used to produce a compressed material with a cylindrical pellet shape having a diameter of 8 mm and a length of 30 mm, thereby obtaining a compressed biomass (compressed material used in pulp production) with a specific gravity of 0.95 and a water content of 10%. Except for using such a compressed biomass, pulp is obtained in a manner similar to that in Example 1.

[0076] (Example 6)

[0077] As the raw material of the pulp, OPT is used, and in steps similar to those in Example 1, a pulverized material with an average length of 30 mm, an average outer diameter of 1.5 mm, and a content rate of the pulverized material with favorable dimensions of 60% is prepared.

[0078] Thereafter, in order to compress the pulverized material, a granulator is used to produce a compressed material with a cylindrical pellet shape having a diameter of 10 mm and a length of 50 mm, thereby obtaining a compressed biomass (compressed material used in pulp production) with a specific gravity of 1.15 and a water content of 10%. Except for using such a compressed biomass, pulp is obtained in a manner similar to that in Example 1.

[0079] (Comparative Example 1)

[0080] As the raw material of the pulp, OPT is used, and in steps similar to those in Example 1, a pulverized material with an average length of 35 mm, an average outer diameter of 1.5 mm, and a content rate of the pulverized material with favorable dimensions of 90% is prepared.

[0081] Thereafter, in order to compress the pulverized material, a triaxial volume reduction machine is used to produce a compressed material with a 40 mm square block shape, thereby obtaining a compressed biomass (compressed material used in pulp production) with a specific gravity of 0.28 and a water content of 15%. Except for using such a compressed biomass, pulp is obtained in a manner similar to that in Example 1.

[0082] (Comparative Example 2)

[0083] As the raw material of the pulp, OPT is used, and in steps similar to those in Example 1, a pulverized material with an average length of 15 mm, an average outer diameter of 0.8 mm, and a content rate of the pulverized material with favorable dimensions of 70% is prepared.

[0084] Thereafter, in order to compress the crushed material, a granulator was used to produce a compressed material having a cylindrical pellet shape with a diameter of 10 mm and a length of 50 mm, thereby obtaining a compressed biomass (compressed material used in pulp production) having a specific gravity of 1.40 and a water content of 9%. It was intended to obtain pulp in a similar manner to Example 1, except that this compressed biomass was used, but the defibration was insufficient, so pulp that could be used for paper production was not obtained.

[0085] (Comparative Example 3)

[0086] As a raw material for pulp, OPT was used, and a crushed material having an average length of 25 mm, an average outer diameter of 1.0 mm, and a content rate of crushed material with favorable dimensions of 80% was prepared in steps similar to those in Example 1.

[0087] Thereafter, in order to compress the crushed material, a briquetting machine was used to compress the crushed material into a briquette shape with a diameter of 50 mm and a length of 40 mm, thereby obtaining a compressed biomass (compressed material used in pulp production) having a specific gravity of 1.10 and a water content of 30%. Except for using such a compressed biomass, pulp was obtained in a similar manner to Example 1.

[0088] The pulp obtained from the above Examples and Comparative Examples 1 and 3 was used to produce paper through the following steps.

[0089] 1. (Based on JIS P8220-1) The pulp was disintegrated by rotating the pulper 10,000 times.

[0090] 2. By using a test flat screen with an 18-cut screen (slit width: 0.3 mm), rough fibers such as un-cooked fibers were removed from the slurry of the pulp thus disintegrated.

[0091] 3. (Based on JIS P8221-2) The pulp passing through the screen was beaten by rotating the PFI refiner 10,000 times.

[0092] 4. (Based on JIS P8222) By using a conventional sheet-former, paper with a basis weight of 60 g / m 2 was produced from the pulp thus beaten.

[0093] The evaluation results of the compressed materials, pulp, and paper in the above Examples and Comparative Examples are shown. The evaluation methods and determination criteria are as follows.

[0094] Evaluation of mechanical durability

[0095] The mechanical durability DU of the compressed biomass after forming is measured based on the wood pellet quality standard of the Japan Wood Pellet Association.

[0096] DU = (m1 / m0) × 100 (%)

[0097] m0: Mass before the test

[0098] m1: Mass after the test

[0099] (Determine)

[0100] A: Higher than or equal to 97.5%

[0101] B: Higher than or equal to 96.5% and less than 97.5%

[0102] C: Less than 96.5%

[0103] Evaluation of storage characteristics

[0104] The antifungal property of the compressed biomass is measured based on the "JIS Z 2911 Test Method for Antifungal Property".

[0105] (Determine)

[0106] A: More than or equal to 14 days

[0107] B: More than or equal to 10 days and less than 14 days

[0108] C: Less than 10 days

[0109] Evaluation of the sieve passing rate

[0110] When allowing the pulp slurry obtained by such decomposition to pass through a test flat sieve with a 18-mesh sieve (slit width: 0.3 mm), the sieve passing rate S is measured.

[0111] S = (m1 / m0) × 100 (%)

[0112] m0: Mass of the pulp before the slurry passes through the sieve

[0113] m1: Mass of the pulp after the slurry passes through the sieve

[0114] * The mass of the pulp is measured in a completely dry state (a state of obtaining a constant mass in a 105 °C dryer).

[0115] (Determine)

[0116] A: Higher than or equal to 95%

[0117] B: Higher than or equal to 90% and less than 95%

[0118] C: Less than 90%

[0119] Strength evaluation

[0120] Based on “JIS P8113 Paper and board - Determination of tensile properties - Part 2: Constant rate of elongation method”, the tensile test of the paper is carried out and the tensile index is measured.

[0121] (Determination)

[0122] A: Greater than or equal to 35 Nm / g

[0123] B: Greater than or equal to 25 Nm / g and less than 35 Nm / g

[0124] C: Less than 25 Nm / g

[0125] [Table 1]

[0126]

[0127]

[0128] [Table 2]

[0129]

[0130] In all the embodiments, the tensile test results of the paper are A or B, thus proving that there are no problems in actual use.

Claims

1. A pulp production method, which includes defibrating woody materials through a cooking treatment using an aqueous alkali solution, wherein the woody materials include compressed materials obtained by compressing crushed materials of palm plants, and the compressed materials have a specific gravity greater than or equal to 0.35 and less than or equal to 1.30 and a water content less than or equal to 25% by mass.

2. The pulp production method according to claim 1, wherein The compression material has a surface area of less than or equal to 15 cm 2 .

3. The pulp production method according to claim 1, wherein the crushed materials include crushed materials having dimensions with a length longer than or equal to 0.6 mm and shorter than or equal to 40.0 mm and an outer diameter greater than or equal to 0.08 mm and less than or equal to 1.5 mm, and the crushed materials having the above dimensions have a content rate higher than or equal to 70% by mass based on the total mass of the crushed materials.

4. The pulp production method according to claim 1, wherein the crushed materials are crushed materials in which the amount of parenchyma has been reduced through classification performed after crushing the palm plants.

5. The pulp production method according to claim 1, wherein the crushed materials are crushed materials in which the amount of sugars has been reduced through water washing performed after crushing the palm plants.

6. A paper production method, including: a pulping step of producing pulp through the pulp production method according to any one of claims 1 to 5; and a step of obtaining paper by skimming and drying the pulp.

7. A compressed material used in pulp production, wherein the compressed material is obtained by compressing crushed materials of palm plants, and the compressed material has a specific gravity greater than or equal to 0.35 and less than or equal to 1.30 and a water content less than or equal to 25% by mass.

Images