Essential oil extraction methods

Abstract

This project aims to provide a novel and useful method for extracting essential oils, while also promoting the effective utilization of peeled cores. [Solution] The method for extracting essential oils comprises a grinding step of grinding wood raw material to obtain a pulverized product, a distillation step of distilling the pulverized product to obtain a distillate, a separation step of separating the distillate into essential oil and aromatic distilled water, and a water removal step of removing trace amounts of water contained in the essential oil obtained in the separation step. In the water removal step, it is preferable to remove frozen water by cooling the essential oil obtained in the separation step to a temperature below the freezing point of water and higher than the freezing point of the essential oil components. It is preferable to use the peeled core 4 remaining after obtaining veneers 3 continuously with a rotary lathe as the wood raw material. The high-purity essential oil obtained by the present invention can be used for the same purposes as in the conventional method, and the pulverized product after essential oil extraction can be reused alone or mixed with other materials in the manufacture of wood fiberboard such as MDF or wood board such as particleboard.

Description

Technical Field

[0001] The present invention relates to a method for extracting essential oil from wood.

Background Art

[0002] Wood, especially coniferous wood such as cypress, contains a lot of phytolaccadins which are fragrant components, and is known to have medical effects such as stress relief, vitality recovery, and improvement of depression. Furthermore, it has also been reported to have effects such as antibacterial, insect repellent, and deodorizing.

[0003] As a method for exerting such effects, extracting essential oil from trees such as cypress is disclosed in Patent Documents 1, 2, etc. below. Patent Document 1 discloses a method for extracting essential oil from a cypress material composed of cypress trunk, cypress leaves or cypress fruits. Patent Document 2 discloses a method for extracting essential oil from the rootstock of cypress.

[0004] By the way, a general manufacturing method of plywood is to peel the bark of the log, cut it into a predetermined length (for example, 2000 to 2150 mm), and after performing a steaming treatment if necessary (especially in the case of coniferous logs), cut it into thin veneers (raw veneers) with a thickness of about several millimeters in a state of being centered and in the manner of peeling the hat, dry this to a predetermined moisture content and cut it into a predetermined size, stack them with the fiber directions orthogonal to each other and perform hot pressing to manufacture plywood (see FIGS. 1 and 2). However, at the end of cutting into veneers with a rotary lathe, a long cylindrical bar (peeled core) with a diameter of about 50 mm inevitably remains. At present, the peeled core is used as a raw material for manufacturing wood-based boards such as MDF (medium density fiberboard) by pulverizing it into chips, as a raw material for cardboard, or for protecting seedlings with a dike, or as a biomass fuel, but the effective utilization of the large amount of peeled cores generated in the plywood manufacturing process has been insufficient.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] As described in Patent Documents 1 and 2, the extraction of essential oil from wood generally involves a grinding step to obtain a pulverized material by crushing the wood raw material, a distillation step to obtain a distillate by distilling the pulverized material, and a separation step to separate the distillate into essential oil and aromatic distilled water. However, the present inventors have found that even after performing the separation step, it is not possible to obtain essential oil with a purity close to 100%, and that the essential oil obtained after the separation step also contains a small amount of water (about 1% of the essential oil).

[0007] In other words, based on the above findings, the problem that this invention aims to solve is to remove trace amounts of water contained in the essential oil obtained in the separation process (hereinafter sometimes referred to as "post-separated essential oil") to obtain an essential oil of higher purity. Another problem that this invention aims to solve is to make effective use of the peeled core that is generated in large quantities during the plywood manufacturing process. [Means for solving the problem]

[0008] To solve these problems, the invention according to claim 1 of the present application is an essential oil extraction method characterized by comprising: a grinding step of grinding wood raw material to obtain a pulverized product; a distillation step of distilling the pulverized product to obtain a distillate; a separation step of separating the distillate into essential oil and aromatic distilled water; and a water removal step of removing water contained in the essential oil obtained in the separation step.

[0009] The invention according to claim 2 of this application is an essential oil extraction method according to claim 1, characterized in that the water removal step comprises a step of removing frozen water by cooling the essential oil obtained in the separation step to a temperature below the freezing point of water and higher than the freezing point of the essential oil components.

[0010] The invention according to claim 3 of this application is characterized in that, in the essential oil extraction method according to claim 1 or 2, the wood raw material is the peeled core remaining after cutting a log to obtain veneers in a continuous manner.

[0011] The invention according to claim 4 of this application is an essential oil extraction method according to claim 1 or 2, characterized in that the pulverized material obtained by the pulverization step is an elongated, thin plate-shaped pulverized material having dimensions of an average length of 10 to 30 mm, an average width of 3 to 10 mm, and an average thickness of 1 to 2 mm.

[0012] The invention according to claim 5 of this application is an essential oil extraction method characterized by recovering essential oils by freezing and removing water contained in a distillate obtained by distilling a raw material containing essential oil components, to a temperature below the freezing point of water and higher than the freezing point of the essential oil components. [Effects of the Invention]

[0013] According to the present invention as of claim 1, a highly pure essential oil can be extracted by performing a water removal step to remove trace amounts of water contained in the essential oil obtained in the separation step.

[0014] According to the present invention as described in claim 2, as a water removal step, the essential oil obtained in the separation step is cooled to a temperature below the freezing point of water and higher than the freezing point of the essential oil components, thereby removing the frozen water, which allows for efficient removal of water from the essential oil in a short time.

[0015] According to the invention of claim 3, new uses for peeled cores, which previously had limited applications, are provided, thereby expanding the effective utilization of peeled cores. Furthermore, since peeled cores contain more essential oils than other parts of the log, a high essential oil recovery rate can be obtained by extracting essential oils from peeled cores.

[0016] According to the present invention according to claim 4, by using an elongated thin plate-shaped pulverized material having dimensions of an average length of 10 to 30 mm, an average width of 3 to 10 mm, and an average thickness of 1 to 2 mm as the pulverized material obtained by the pulverization step, the essential oil recovery efficiency can be further increased.

[0017] According to the invention according to claim 5, water contained in trace amounts in the distillate obtained by distilling a raw material containing an essential oil component can be efficiently removed in a short time, and a highly pure essential oil can be extracted.

[0018] The essential oil obtained by the present invention can be used for the same applications as in the prior art, and since the purity is high, more effective usage examples can be expected. Further, the pulverized material after essential oil extraction can be reused as a single material or mixed with other materials in the production of wood-based fiberboards such as MDF and wood-based boards such as particle boards.

Brief Description of the Drawings

[0019] [Figure 1] It is a flowchart showing the essential oil extraction method according to the present invention in the order of steps together with the manufacturing process of plywood. [Figure 2] It is a side view schematically showing that the peeled core used in the present invention remains after continuously obtaining veneers with a rotary lathe.

Best Mode for Carrying Out the Invention

[0020] The essential oil extraction method according to the present invention will be described in detail below with reference to FIG. 2.

[0021] (Preparation Step) Prepare logs of coniferous trees such as cypress and cedar, or broad-leaved trees such as eucalyptus and camphor tree. The tree species of the log is not limited as long as it can extract essential oil. The log is, for example, a tree diameter of 160 to 500 mm and a length of 2000 to 2150 mm.

[0022] From the perspective of effectively utilizing the peeled cores that remain in large quantities after continuously obtaining veneers from logs using a rotary lathe, it is preferable to extract essential oils using the peeled cores as raw materials. Cutting by a rotary lathe is well-known. As shown in Fig. 1, while rotating the log 1 about its cross-sectional center as an axis, by pressing the cutting edge 2 against the log surface and cutting in the manner of shaving, a thin veneer 3 is continuously manufactured. The cross-sectional center that becomes the rotation axis of the log 1 is the center of the inscribed circle calculated based on the data obtained by measuring the cross-sectional shape of the log 1.

[0023] When continuously obtaining veneers in this way using a rotary lathe, finally, a long rod-shaped peeled core 4 remains. From the perspective of yield, it is preferable to make veneers until the diameter of the peeled core becomes as small as possible. On the other hand, as the diameter of the log decreases, the warp of the obtained veneer increases, and the utility value as a veneer is impaired. Therefore, generally, the diameter of the finally remaining peeled core is about 50 to 60 mm, and the length is the same as the log, 2000 to 2150 mm.

[0024] (Crushing process) The peeled cores prepared in the above preparation step are crushed using a crushing means to obtain crushed material. The crushing means is not limited to those that can crush peeled cores, and known cutting machines or crushers such as chippers, shredders, cutter mills (shear-type crushers), and flakers can be used. For example, by feeding a large number of peeled cores together into a chipper and crushing them into chips, roughly rectangular flat crushed material (average length 25-40 mm, average width 25-40 mm, average thickness 3-5 mm) can be obtained. By further crushing this chipped crushed material with a shredder, roughly rectangular flat crushed material with an average length of 20-35 mm, an average width of 3-20 mm, and an average thickness of 3-5 mm can be obtained. Alternatively, by feeding a large number of peeled cores together into a chipper and crushing them into chips, a roughly rectangular, flat material (average length 25-40 mm, average width 25-40 mm, average thickness 3-5 mm) can be obtained. This chipped material can then be further compressed and cut in a cutter mill (shear-type crusher) to grind and crush it, resulting in a long, thin, elongated, flat material with an average length of 10-30 mm, an average width of 3-10 mm, and an average thickness of 1-2 mm. Alternatively, by crushing a large number of peeled cores together in a flaker, a roughly rectangular, thin, flat material with an average length of 50-60 mm, an average width of 50-60 mm, and an average thickness of 1-1.5 mm can be obtained.

[0025] (Distillation process) The pulverized material obtained in the above grinding process is distilled to obtain a liquid distillate (a mixture of essential oil and water). The method of processing in the distillation process is not particularly limited and can be carried out using commonly used distillation equipment. For example, the pulverized material can be heated by steam distillation using heated steam or by hot water distillation by heating and boiling it in water, and the gas produced at that time can be cooled with a cooling device to obtain a distillate consisting of essential oil and water.

[0026] (separation process) The distillate obtained in the above distillation process is separated into essential oil and water. The processing method in the separation process is not particularly limited as long as it can separate the distillate into essential oil and water. For example, by letting the distillate stand for a certain period of time or by performing treatments such as redistillation, the essential oil layer and the water layer can be separated, and the essential oil layer can be recovered from that state. In addition, the water in the distillate is aromatic hydrosol (aroma water) containing trace amounts of essential oil components, so it can be recovered and used in fragrances, cosmetics, etc. If the essential oil and water are automatically separated and recovered during the above distillation process, the separation process can be omitted.

[0027] (Water removal process) The essential oil separated and recovered in the above separation process still contains a small amount of water (about 1% of the essential oil), so a water removal process is carried out to remove this water and further increase the purity of the essential oil. The water removal process is not particularly limited as long as it can remove the small amount of water dispersed in the separated essential oil. For example, by cooling the separated essential oil to a temperature below the freezing point of water (0 degrees Celsius) and higher than the freezing point of the essential oil components, only the small amount of water contained in the separated essential oil can be frozen, and the frozen water (ice) can be removed by filtering it in this state. The amount of water contained in the separated essential oil can also be reduced by repeating the distillation process multiple times in the above distillation process, or by letting the distillate stand for a long time in the above separation process, or by separating the essential oil from the small amount of water by centrifugal force, but the above freezing treatment allows for efficient removal of water in a short time. It should be noted that the freezing point of essential oils is difficult to determine definitively due to factors such as tree species, growing environment, and extraction method, as well as the complex mixture of various components with different freezing points, such as α-pinene and limonene. However, it is generally in the range of -20 to -70 degrees Celsius. Therefore, cooling from 0 to -20 degrees Celsius will bring almost all essential oils, even those with varying freezing points, above their freezing point, allowing for an appropriate water removal process.

[0028] The essential oils obtained as described above have a high purity of nearly 100%, and, like conventional technologies, can be used in various applications (fragrances, cosmetics, antibacterial agents, insect repellents, deodorizers, detergents, aromatherapy, etc.) to exert effects such as stress relief, vitality restoration, improvement of depression, antibacterial properties, insect repellents, and deodorizing properties, with the expectation of even greater effects.

[0029] (Reuse process) The pulverized material remaining after essential oil extraction can be reused either as a standalone material or mixed with other materials in the manufacture of wood fiberboards such as MDF and wood-based boards such as particleboard.

[0030] The present invention will be specifically described below with reference to examples.

[0031] (preparation process) In this example, a cypress log from Shizuoka Prefecture (240 mm in diameter, 2100 mm in length) was used. The log was rotated in a rotary lathe and a cutting blade was applied to the surface to cut it into veneers. After this, many long cylindrical cores (50 mm in diameter, 2100 mm in length) were prepared. The veneer cutting was performed under the following conditions. • Rotary race: Rotation speed 145 m / s • Cutting blade: Length 2200mm, tip thickness 0.5~16mm • Solid wood: 1.85mm thick

[0032] (Grinding process) After cutting the veneer, the remaining cores were put into a chipper in large quantities and crushed into chips, resulting in roughly square-shaped chips (average length 25-40 mm, average width 25-40 mm, average thickness 3-5 mm). These chips were then further compressed and cut in a cutter mill (shear-type crusher) to crush and grind them, yielding 36 kg of elongated, thin cypress wood chips with an average length of 20 mm, an average width of 5 mm, and an average thickness of 1.5 mm.

[0033] (Distillation process) The cypress pulverized material obtained in the above grinding process was distilled using a steam distillation apparatus, the discharged steam was collected, cooled in a cooling apparatus, and the distilled water containing cypress essential oil was recovered in a recovery apparatus.

[0034] (separation process) By allowing the cypress essential oil-containing distilled water, which was gradually recovered during the distillation process described above, to stand in the recovery apparatus, the difference in specific gravity between the cypress essential oil and water separated them into an upper layer of cypress essential oil and a lower layer of aromatic distilled water. By distilling and separating 36 kg of the elongated, thin, plate-shaped cypress pulverized material obtained in the pulverization process, 450 mL (402.30 g) of cypress essential oil and 60 L of aromatic distilled water were obtained.

[0035] (Water removal process) The cypress essential oil separated in the above separation process was cooled to a temperature below the freezing point of water but higher than the freezing point of the cypress essential oil (for example, -18 to -20 degrees Celsius). This froze the water scattered as small bubbles in the cypress essential oil, and the oil was then filtered through a filter (mesh size 126-3) to remove the frozen water (ice), thereby obtaining a high-purity cypress essential oil. Since the dimensions of the removed ice were 0.5 to 2 mm, it was confirmed that by using a filter with a mesh size that allows ice of this size to pass through, it is possible to remove the ice and extract an essential oil with reduced water content and higher purity.

[0036] To demonstrate the advantages of implementing a water removal process, a comparative test was conducted on the purity of cypress essential oil obtained in the above example where a water removal process was implemented, and the purity of cypress essential oil (essential oil after separation) obtained by performing the same preparation, grinding, distillation, and separation processes as in the above example, but omitting the water removal process. The results are shown in Table 1. By implementing the water removal process in the above example, 3.95g of the 4.41g of water contained in the cypress essential oil recovered after the separation process was removed, resulting in cypress essential oil with a purity of approximately 99.9%, demonstrating the effect of significantly improving the purity of the essential oil.

[0037] [Table 1]

[0038] The purity (%) of the essential oil is calculated as the weight of the essential oil / the total weight, where the total weight is the weight of the essential oil + the weight of the water. The pulverized material obtained in the grinding process contains various impurities, but these are substantially removed during the subsequent distillation and separation processes. Therefore, there are almost no impurities remaining in the separated essential oil, and any remaining impurities are in very small amounts and have little effect on the purity of the essential oil, so they can be ignored.

[0039] In the above embodiment, essential oil was extracted from the peeled heartwood remaining after cutting cypress logs into veneers using a rotary lathe. To demonstrate the advantages of using the peeled heartwood as the material for essential oil extraction, the essential oil recovery rate (amount of essential oil extracted per unit weight of raw material) was tested under different extraction conditions. Unless otherwise specified, each process was carried out under the same conditions as described in the embodiment.

[0040] First, in addition to the cypress used in the example, we also conducted a comparative test on the essential oil recovery rate when essential oil was extracted from the peeled heartwood of Japanese cedar (Cryptomeria japonica), and obtained the results shown in Table 2. From these results, it was confirmed that cypress yielded a better essential oil recovery rate than Japanese cedar as a raw wood species.

[0041] [Table 2]

[0042] Next, we conducted a comparative test of essential oil recovery rates when extracting essential oil from different parts of the cypress log, and obtained the results shown in Table 3. From these results, it was confirmed that using the peeled heartwood yielded the best essential oil recovery rate.

[0043] [Table 3]

[0044] Next, we conducted comparative tests on the essential oil recovery rate when extracting essential oil from crushed material obtained by crushing the core of cypress logs, varying the shape and dimensions of the material. The results are shown in Table 4. From these results, we found that the essential oil recovery rate was best when using elongated, thin plate-shaped crushed material obtained by crushing roughly square, flat chip-shaped crushed material with a chipper, and then further compressing, cutting, and grinding it with a cutter mill (shear-type crusher). The best results were obtained using elongated, thin plate-shaped crushed material with an average length of 20 mm, an average width of 5 mm, and an average thickness of 1.5 mm. Based on these results, we further extracted essential oil from crushed material of various dimensions. When essential oil was extracted from elongated, thin plate-shaped crushed material with an average length of 10-30 mm, an average width of 3-10 mm, and an average thickness of 1-2 mm, the essential oil recovery rate was approximately 1% or more, confirming that essential oil can be extracted efficiently.

[0045] [Table 4]

[0046] The reason why the essential oil recovery rate is good when using elongated, thin, plate-shaped pulverized material obtained by further compressing, cutting, and grinding chip-shaped pulverized material obtained by cutting with a chipper is that it has a shape and dimensions that make it easy to extract essential oils, and in the process of further compressing, cutting, and grinding the chip-shaped pulverized material with a cutter mill (shear-type pulverizer), the essential oil is extracted and moves to the surface of the elongated, thin, plate-shaped pulverized material, where it is in a state that is easy to extract, and further cutting the chip-shaped pulverized material obtained by cutting with a chipper (which has a relatively smooth surface) The elongated, thin, plate-like pulverized material obtained by compressing, cutting, and grinding in a termiller (shear-type pulverizer) forms numerous microscopic irregularities on its surface. This increases the surface area of ​​each elongated, thin, plate-like pulverized material that comes into contact with water vapor. Furthermore, water vapor can spread through the voids formed between the irregular surfaces of the elongated, thin, plate-like pulverized material. Additionally, the previously tightly packed wood fibers separate, creating voids that allow water vapor to penetrate not only the surface but also the interior of the woody material. This is presumed to improve the efficiency of recovering cypress essential oil-containing distilled water during the distillation process.

[0047] Although the present invention has been described in detail above with reference to examples and test examples, the present invention can be implemented in a wide variety of ways by modifying or changing it within the scope of the invention as defined by the claims. [Explanation of Symbols]

[0048] 1 Log 2 cutting blade 3. Single-ply 4 Peeled core

Claims

1. An essential oil extraction method characterized by comprising: a grinding step of grinding wood raw material to obtain a pulverized product; a distillation step of distilling the pulverized product to obtain a distillate; a separation step of separating the distillate into essential oil and aromatic distilled water; and a water removal step of removing water contained in the essential oil obtained in the separation step.

2. The essential oil extraction method according to claim 1, characterized in that the water removal step comprises a step of removing frozen water by cooling the essential oil obtained in the separation step to a temperature below the freezing point of water and higher than the freezing point of the essential oil components.

3. The method for extracting essential oils according to claim 1 or 2, characterized in that the wood raw material used is the peeled core remaining after cutting a log to obtain veneers in a continuous manner.

4. The essential oil extraction method according to claim 1 or 2, characterized in that the pulverized material obtained by the pulverization step is an elongated, thin, plate-shaped pulverized material having dimensions of an average length of 10 to 30 mm, an average width of 3 to 10 mm, and an average thickness of 1 to 2 mm.

5. A method for extracting essential oils, characterized by recovering essential oils by freezing and removing water contained in a distillate obtained by distilling a raw material containing essential oil components, to a temperature below the freezing point of water and higher than the freezing point of the essential oil components.

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