METHOD FOR SEPARATING CELLULOSE

Abstract

In a method, a cellulose component is separated from plant materials consisting of cellulose, hemicellulose and lignin as principal components. The method includes the step of: rinsing the plant materials into a separating agent comprising ethylene glycols, heating the separating agent with the plant materials up to a high temperature less than the boiling point of the separating agent and reacting the separating agent with the plant materials, evaporating the hemicellulose from the separating agent reacted with the plant materials while dissolving the lignin of the plant materials into the separating agent, finally collecting the remaining cellulose component of the plant materials floating on the surface of the separating agent.

Claims

1. A method of separating cellulose component from plant materials consisting of cellulose, hemicellulose and lignin as principal components, the method comprising the step of: rinsing the plant materials into a separating agent comprising ethylene glycols, heating the separating agent with the plant materials up to a high temperature less than the boiling point of the separating agent and reacting the separating agent with the plant materials, evaporating the hemicellulose from the separating agent reacted with the plant materials while dissolving the lignin of the plant materials into the separating agent, finally collecting the remaining cellulose component of the plant materials floating on the surface of the separating agent.

2. The method of separating cellulose component from plant materials consisting of cellulose, hemicellulose and lignin as principal components, wherein the separating agent contains di-ethylene glycols or tri-ethylene glycols as a main component and the heating temperature of the separating agent is set at a temperature less than the boiling points of di-ethylene glycol (244° C.) or the boiling points of tri-ethylene glycol (287° C.)

3. The method of separating cellulose component from plant materials consisting of cellulose, hemicellulose and lignin as principal components, wherein the plant materials are selected from non woody pulp consisting of bamboo, bagasse and straw.

4. The method of separating cellulose component from plant materials consisting of cellulose, hemicellulose and lignin as principal components, wherein the plant materials is bamboo, the separating agent is tri-ethylene glycol and the heating temperature is in a range of 260° C. to 280° C.

5. The method of separating cellulose component from plant materials consisting of cellulose, hemicellulose and lignin as principal components, further comprising bleaching step by immersed in an aqueous solution of hypochlorous acid and caustic soda.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing (s) will be provided by the Office upon request and payment of the necessary fee.

[0032] FIG. 1 is a configuration view of a system illustrating a preferred embodiment of a method for separating cellulose of the present Invention.

[0033] FIG. 2 is a view illustrating an example of a system that washes and miniaturizes crude cellulose in the embodiment.

[0034] FIG. 3 is a view illustrating a second embodiment.

[0035] FIG. 4 is a view illustrating a third embodiment.

[0036] FIG. 5 is a flowchart illustrating a step A of separating cellulose.

[0037] FIG. 6 is a flowchart illustrating a step B of separating cellulose.

[0038] FIG. 7 is a flowchart illustrating a step C of separating cellulose.

[0039] FIG. 8 is a color picture drawing showing bamboo raw material.

[0040] FIG. 9 is a color picture drawing showing bamboo cellulose before bleaching.

[0041] FIG. 10 is a color picture drawing showing celluloses in respective bleaching conditions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Hereinafter, the present Invention will be described in detail on the basis of specific examples illustrated in drawings. FIG. 1 and FIG. 2 illustrate a preferred embodiment of a method for separating cellulose of the present invention. In the drawings, a dissolution reservoir 1 stores tri-ethylene glycol (TEG) as a separating agent therein.

[0043] In the dissolution reservoir 1, the separating agent is heated to a temperature in a range of 260° C. to 280° C. in a state in which one or more wood-based raw materials selected from the group consisting of bamboo, wood, wood cotton, and cotton are injected therein and held for 0.5 to 1.5 hours, hemicellulose evaporates as the temperature increases, lignin dissolves in the separating agent, the separating agent including lignin is extracted, and crude cellulose that floats on the separating agent remains on the reservoir bottom and is collected. Meanwhile, as the raw material, it is also possible to use vegetable, fruit, and cereal (food fibers) or pulp (recycled fibers).

[0044] A condenser 7 that condenses the hemicellulose component that evaporates from the separating agent is connected to the dissolution reservoir 1, the condensed hemicellulose is received in a condensation reservoir 8, and the pH thereof is monitored.

[0045] In addition, the separating agent extructed from the reservoir bottom of the dissolution reservoir 1 is received in a receiving reservoir 2 and heated using a heating furnace 3, the heated separating agent is sent out using a circulation pump 4, a part thereof is circulated to the dissolution reservoir 1, and the separating agent in the dissolution reservoir 1 is heated.

[0046] The remainder of the separating agent that is circulated using the circulation pump 4 is sent to a vacuum evaporation reservoir 6, the separating agent is evaporated in a vacuum, lignin is separated on the reservoir bottom of the vacuum evaporation reservoir 6, and lignin is transferred using a transfer pump 16, condensed using a condenser 19, and received in a receiving reservoir 18. A chimney 17 is a chimney of a heating furnace 3.

[0047] The vacuum-evaporated separating agent is condensed using a condenser 13, received in a receiving reservoir 14 in which a negative pressure is formed using a vacuum pump 15, and returned to the separating agent-receiving reservoir 2 using a pump 20.

[0048] Meanwhile, the crude cellulose that remains on the reservoir bottom of the dissolution reservoir 1 as a solid content is washed, cooled, and then extracted from the dissolution reservoir 1, a fiber is cut and washed in a rotary cutting water reservoir 9 and thus becomes fine cellulose, the fine cellulose is bleached in a bleaching reservoir 10, furthermore, dehydrated in a centrifugal separator 11, and then, pressurized mechanically, for example, using a high-pressure filter 21, and miniaturized, that is, turned into a cellulose nanofiber (CNF), the cellulose nanofiber is removed, and discharged water is treated using a treatment facility 12.

[0049] Here, the separation method will be descried. In the dissolution reservoir 1, when the liquid temperature of the separating agent reaches a temperature in a range of 200° C. to 260° C., for example, 200° C., the hemicellulose component begins to evaporate, and the pH of a condensate thereof indicates a strong acidity. The pH of the condensate increases until 260° C. and reaches 5 to 6 at 275° C., the amount of the hemicellulose component distilled away decreases, when fractional distillation stops, the heating is stopped, and the condensate is held to stand at the temperature for 0.5 to 1.5 hours.

[0050] Next, the separating agent in the dissolution reservoir 1 is extracted from the reservoir bottom, and then, the solid content (the crude cellulose) in the dissolution reservoir 1 is washed, cooled, and fed into the rotary cutting water reservoir 9, the crude cellulose is washed using a rotating stirring blade and cut to be fine cellulose, then, as illustrated in FIG. 2, the fine cellulose is extracted from the rotary cutting water reservoir 9 using a transfer pump 21, filtered using a filter 20, separated using a strainer 22, and received in a receiving reservoir 23. After that, the fine cellulose is immersed and bleached in an aqueous solution of hypochlorous acid and caustic soda in the bleaching reservoir 10, and it is possible to further miniaturize the fine cellulose.

[0051] Meanwhile, the liquid extracted from the dissolution reservoir 1 is colored to a dark brown color, when the liquid is evaporated and gasified in the vacuum evaporation reservoir 6, it is possible to collect pressure-sensitive adhesive-like lignin on the reservoir bottom, when the evaporated and gasified vapor is condensed, it is possible to collect and reuse the separating agent.

[0052] The yield was 24 wt % (the temperature of the dissolution reservoir: 275° C. or lower) for hemicellulose, 49 wt % (the temperature of the dissolution reservoir: 275° C. or lower) for cellulose, 14 wt % for lignin, and 13 wt % for others.

[0053] FIG. 3 illustrates a second embodiment. In the present example, a facility that separates cotton derived from an old cloth as a wood-based raw material is further provided. In the drawing, an old cloth-separating reservoir 20 stores ethylene glycol or tri-ethylene glycol therein a a separating agent, and when an old cloth 201 made of a fiber of polyester, cotton, nylon, acryl, and the like as a material is injected into the separating agent in the old cloth-separating reservoir 20, and the separating agent is heated to 200° C. to 280° C., cotton 204 floats on the separating agent, polyester, nylon, and acryl are dissolved in the separating agent, and buttons or clasps sink on the reservoir bottom and are separated.

[0054] In a dissolution reservoir 100, tri-ethylene glycol (TEG) is stored as a separating agent and heated using a heating furnace 101. A chimney 114 is the chimney of the heating furnace 101. In the dissolution reservoir 100, in addition to a wood-based raw material 120 such as bamboo, wood, marijuana, wood cotton, or cotton, the cotton 204 derived from an old cloth is also injected into the separating agent, the separating agent is heated up to a temperature in a range of 260° C. to 280° C., for example, 275° C. that is a temperature at which hemicellulose dissolves and held for 0.5 to 1.5 hours, crude cellulose is left as a solid content on the reservoir bottom, lignin dissolves in the separating agent, and the separating agent including lignin is withdrawn.

[0055] The dissolution reservoir 100 is configured that the separating agent in which lignin is dissolved can be extracted from the reservoir bottom, the extracted separating agent is transferred using a pump 102, a part thereof is received in a receiving reservoir 108, and the remainder is sent to a lignin-separating tower 103, the separating agent is evaporated in a vacuum, lignin is separated, the evaporated separating agent is condensed, returned to the receiving reservoir 108, and circulated to the dissolution reservoir 100 using a circulation pump 107.

[0056] In addition, from the separating agent extracted from the dissolution reservoir 100, moisture is evaporated and separated in a water-separating tower 104, the separating agent is returned to the receiving reservoir 108, and the separated moisture is condensed and retained in a tank 106.

[0057] The crude cellulose remaining as the solid content on the reservoir bottom of the dissolution reservoir 100 is washed and cooled using a washing water 121, and then extracted from the dissolution reservoir 100, a fiber is cut and washed in a rotary cutting water reservoir 109, bleached in a bleaching reservoir 102, furthermore, miniaturized, washed, and filtered using a high-pressure filter 113, thereby obtaining a gel-form cellulose nanofiber (CNF).

[0058] FIG. 4 illustrates a third embodiment and illustrates a continuous separation method. In a dissolution reservoir 300, tri-ethylene glycol (TEG) is stored as a separating agent.

[0059] An extraction portion of the separating agent is connected to a reservoir bottom of the dissolution reservoir 300, an on-off valve 301 is provided in the extraction portion, the dissolution reservoir is connected to a variable transfer device 304 such as a screw, the variable transfer device 304 is inclined, and a liquid-draining region 305 in which a roller or the like is used is provided on an upper end side of the variable transfer device. Liquid-drained crude cellulose is injected into a rotary cutting water reservoir 306, washed, cut, and thus becomes fine cellulose, the fine cellulose is sent to a bleaching reservoir 307, bleached using an aqueous solution of hypochlorous acid and caustic soda, and then turned into CNF using a CNF-producing device 308 configured of the same system as in the above-described embodiment.

[0060] Meanwhile, one or a plurality of wood-based raw materials selected from the group consisting of bamboo, wood, wood cotton, and cotton is intermittently injected into the dissolution reservoir 300, the vapor of a hemicellulose component is condensed using a condenser 302 and received in a receiving reservoir 303, and the pH of a condensate in the receiving reservoir 303 is monitored.

[0061] The separating agent is extracted from the lowest end side of the variable transfer device 304 and transferred to a vacuum evaporation tower 310, the separating agent is evaporated in a vacuum, lignin is separated and collected, the vacuum-evaporated separating agent is condensed using a condenser 311 and collected in a separating agent-collecting reservoir 312 in which a negative pressure is formed using a vacuum pump 313.

[0062] The separating agent in the separating agent-collecting reservoir 312 is extracted using a circulation pump 314, heated using a circulation heating portion 315, circulated to the dissolution reservoir 300, thereby heating the dissolution reservoir 300.

[0063] Next, the separation method will be descried. Into the dissolution reservoir 300, a wood-based raw material such as bamboo is injected, and the separating agent in the dissolution reservoir 300 is heated. When the liquid temperature of the separating agent reaches a temperature in a range of 200° C. to 260° C., for example, 200° C., the hemicellulose component begins to evaporate, and the pH of a condensate thereof indicates a strong acidity. The pH of the condensate increases until 260° C. and reaches 5 to 6 at 275° C., the amount of the hemicellulose component distilled away decreases, when fractional distillation stops, the heating is stopped, and the condensate is held to stand at the temperature for 0.5 to 1.5 hours.

[0064] Next, the on-off valve 301 of the extraction portion of the dissolution reservoir 300 is opened, the separating agent is separated from the crude cellulose and extracted from the lowest end side of the variable transfer device 304, the separating agent is evaporated in a vacuum in the vacuum evaporation tower 310, lignin is separated and collected, the vacuum-evaporated separating agent is condensed using the condenser 311 and collected in the separating agent-collecting reservoir 312 in which a negative pressure is formed using the vacuum pump 313.

[0065] In the variable transfer device 304, the separated crude cellulose is washed and cut in the rotary cutting water reservoir 306, then, bleached in the bleaching reservoir 307, miniaturized, and then, turned into CNF.

[0066] The separating agent collected in the separating agent-collecting reservoir 312 is heated to a predetermined temperature in the circulation heating portion 315 and circulated to the dissolution reservoir 300, then, a wood-based raw material such as bamboo is injected therein, and the same work as described above is carried out, whereby the cellulose can be continuously separated and collected.

Example: Bamboo Processing Flow

[0067] In a papermaking method of separating cellulose component from plant materials or pulp raw materials consisting of cellulose, hemicellulose and lignin, a kraft method has been used in which an alkaline agent (mainly caustic soda) has been used, and a resin content lignin other than pulp is water-dissolved using a large continuous digester. In the paper making field, a cellulose component is used as a pulp, and lignin is separated as a black liquor, but a continuous digester is large in size up to 60 m in height, and it is necessary to treat at a high temperature of 150 to 160 ° C. for a long time about 5 hours, and there was a disadvantage that lignin could not be effectively utilized.

[0068] Therefore, according to the present invention, in to only 1) cellulose can be separated from the plant materials or the pulp raw materials by using ethylene glycols as a separating agent, but also 2) hemicellulose and lignin can be recovered and utilized. As the pulp raw materials, there are a wood-based pulp and a non-wood-based pulp, and as the latter non-wood-based pulp raw material, there are included a bamboo, a bagasse, a straw, and the like, and therefrom a plenty of good quality cellulose component can be separated. Therefore, a method of separating cellulose from the bamboo material is a typical example of a non-wood-based pulp and the ethylene glycols as a separating agent was carried out as follows, and 25% of bamboo vinegar as hemicellulose, 25% of lignin, and the remaining 50% of cellulose were separated and recovered.

[0069] First, the bamboo material is cut to a size able to let the whole material being immersed in the separation liquid in the separation device (10) (as shown in FIG. 8). An atmospheric pressure cooker with a capacity of 50 liters is prepared here. Approximately three times as much separating agent as the bamboo stock is used. As a separating agent, ethylene glycols are added. Ethylene glycol, diethylene glycol, triethylene glycol, and poroethylene glycol can be used for the ethylene glycol agent. In terms of cost, especially ethylene glycol, di-ethylene glycol, and tri-ethylene glycol can be selected. High temperatures below the boiling point can be used for reacting the bamboo with the separating agent. The temperature above the boiling point of the separating agent cannot be used and is not good for evaporation recovery of hemicellulose from the separating agent. The boiling point of the separating agent can be determined by the composition of the separating agent and the reaction condition pressure. Since the boiling point of ethylene glycol at atmospheric pressure is 197° C., the boiling point of di-ethylene glycol is 244° C., and the boiling point of tri-ethylene glycol is 287° C., usually, the tri-ethylene glycol is used as a main component of the separating agent and ethylene glycol or diethylene glycol can be added to adjust the boiling point of the separating agent, so a reaction temperature can be selected in a temperature range of 200° C. to 287° C. at an atmosphere pressure, but in the case of a bamboo material, a high temperature of 270° C. or 280° C. is advantageous for the separating reaction.

[0070] Table 1 shows the weight of the raw material and the weight of the separating agent when the decomposing solution was heated to 270° C. for 1 hour, 2 hours, and 3 hours, 280° C. for 1 hour, 2 hours, and 3 hours in process A shown in FIG. 5 below using tri-ethylene glycol at or below the boiling point of the decomposing agent in the separating apparatus. In addition, (2) the distillate (wood vinegar) evaporates first, and then (3) the lignin reacts with the separating agent to be dissolved in the solution, and finally (4) the residual cellulose floats on the separating agent. They were measured respectively. This is illustrated in Table 2.

[0071] FIG. 9 is a photograph showing each of residual celluloses. Both are black, so they are subjected to a bleaching process. It was treated in the bleaching step of bamboo cellulose shown in process B below. In the bleaching step, 100 grams of bleaching agent consisting of hypochlorous acid and caustic soda were used for 100 grams of bamboo cellulose. Photograph of FIG. 10 shows the status of sample 1 to sample 7 subjected to each bleaching treatment.

[0072] As a result of the analytical test, it was found that lignin was removed in the dissolution test sample as compared with the bamboo raw material. There was no large change even if the dissolution condition was changed.

[0073] The overall bamboo processing flow is shown in process C of FIG. 7. If 35 tons of bamboo were treated, we would get 8.75 tons of bamboo vinegar as hemicellulose and Lignin of about 8.75 tons to be dissolved in the separating agent, so the lignin can be used in adhesives and fertilizer applications. The cellulose floating (4) on the separating agent would be 17.5 tons. Lignin is solidified and used as biomass fuel. Cellulose (5) is shredded by a coarse cutter and becomes a heat insulating material (6). Then, a part of them is processed by a bleaching apparatus to get bleaching cellulose 17.5 tons, 7.9 tons of which are dry pulverized (10 kg/hr) to become powders (7), which are used for the addition of cosmetic. On the other hand, 9.6 tons can be wet-milled (12k g/hr) to be 2% aqueous dispersion, which are used for cream or antimicrobial spray (9). On the other hand, In case of cellulose nanofibers (CNFs) made by a CNF device, it is used to increase the strength of paper tubes. If the cellulose fibers can be separated from the woody raw material in good state according to this invention with a separating agent, they can be used in many applications as described above.

[0074] Note that, although a bamboo material is used as the non-wood pulp, bagasse, straw, or the like, which is another non-wood pulp, can be used as a material for recovering cellulose fibers.

TABLE-US-00001 TABLE 1 Each separation condition Processing condition Raw material Separator Temperature Time weight weight Process (° C.) (h) (g) (g) Separation 270 1 100.67 315.12 270 2 100.19 314.21 270 3 100.41 311.22 280 1 100.51 285.96 280 2 100.28 317.55 280 3 99.70 294.36

TABLE-US-00002 TABLE 2 Bamboo separation processing yield Processing condition Distillatory Distillatory Temperature Time Cellulose Cellulose solution solution Solvents* Melt Process (° C.) (h) (g) (%) (%) (%) (g) (%) Separation 270 1 55.55 55.18 14.46 14.36 30.66 30.46 270 2 45.19 45.10 18.12 18.09 36.88 36.81 270 3 37.52 37.37 18.62 18.54 44.27 44.09 280 1 45.66 45.43 22.62 22.51 32.23 32.07 280 2 38.37 38.26 18.50 18.45 43.41 43.29 280 3 24.21 24.28 21.03 21.09 54.46 54.62