Wood materials made from paper mulberry core and wooden products made from them

Abstract

To provide a wooden material that can be reused as a raw material for wooden products such as wooden daily necessities, wooden stationery, wooden fittings, wooden furniture, wooden models, and wooden crafts by effectively utilizing mulberry core material that has only been used for firewood for camping or composting, instead of being incinerated or composted, and to provide wooden products using the same that have sufficient strength. [Solution] Wooden materials 101-104 made from mulberry core material are formed from mulberry core material 1 and are in the shape of a pillar, board, or block. Wooden products are made from this raw material for wooden products, and include wooden daily necessities, wooden stationery, wooden fittings, wooden furniture, wooden models, wooden crafts, and wooden toys.

Description

[Technical Field]

[0001] This invention relates to wooden materials that use the bark of paper mulberry, the raw material for Japanese paper, as a woody material, and various wooden products that use it. [Background technology]

[0002] Paper began to be used in Japan at the latest in the 6th century. Washi is paper made using traditional Japanese techniques and is made from different raw materials than Western paper. The raw materials for washi include kozo (paper mulberry), mitsumata (mitsumata), and gampi (gampi). Washi is made by peeling the bark from these trees, extracting the fibers, defibrating them, and then filtering them on a bamboo screen or mesh to make paper. In particular, paper mulberry is a deciduous shrub with the scientific name Broussonetia × kazinoki, which is a species of the genus Broussonetia in the family Moraceae, order Rosales. In recent years, cultivation has led to a stable supply of paper as a raw material for Japanese paper.

[0003] Washi products made from mulberry are used in a wide range of applications, including household items such as wet towels, kitchen paper, face masks, and packaging, building materials such as shoji paper, agricultural products, and industrial and commercial items such as food packaging and filter material. Furthermore, for example, Patent Document 1 discloses a papermaking strip-shaped tape made from papermaking raw material fibers (limited to plant fibers and excluding animal fibers) that are naturally derived fibers or recycled fibers, in which the papermaking raw material fibers are entangled together around a taut core yarn located toward the center, and the long side ends are uncut and untwisted yarns, the tape having a thickness of 10 to 100 μm, in which the papermaking raw material fibers are entangled while having an average gap of 200 μm or less around the core yarn, with the core yarn being located in the middle or center in the thickness direction, and a paper yarn twist made from the papermaking strip-shaped tape, and a fabric using the papermaking strip-shaped tape.

[0004] Kozo, the raw material for washi paper, grows to a height of 1-6m at maturity, usually 1.5-5m, is easy to cultivate, and can be harvested annually. The core wood, which remains after the bark has been stripped from the kozo logs, was once dried and used in households as firewood for hearths, but with the shift from hearths to gas as fuel, in recent years it has only been used in small quantities as firewood for camping, or cost-intensively chipped and mixed into compost, with the exception of incinerating it as industrial waste.

[0005] In the "Book of Paper Mulberry Purchases and Sales" published in 1887, kozo is listed as "kozo grass." Because kozo had long been treated as a type of grass used as a raw material for Japanese paper, it seems that no one had ever considered using the core material of kozo as lumber. The inventor discovered that dried kozo core not only has a unique lightness and smooth feel, but also has sufficient strength, and found that it can be used as a wooden material and can even be given added value by painting, which led to the completion of this invention. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7719451 Summary of the Invention [Problem to be solved by the invention]

[0007] The purpose of this invention is to effectively utilize mulberry core material, which has previously only been used for firewood and compost, as a wooden material, and to provide a wooden material that can be reused as a raw material for wooden products such as wooden daily necessities, wooden stationery, wooden fittings, wooden furniture, wooden models, and wooden crafts, instead of being incinerated or composted, and to provide wooden products using this material that have sufficient strength. [Means for solving the problem]

[0008] The wooden material made from mulberry core material of the present invention, which has been made to achieve the above-mentioned object, is characterized in that it is formed from mulberry core material and is in the shape of a pillar, board, or block.

[0009] This wooden material made from mulberry core wood may be such that a plurality of the columnar, planar, or block-shaped single pieces are arranged and joined in a single layer or multiple layers to form a columnar bundle with a larger diameter, or a planar bundle with a wider or thicker layer, or a larger block-shaped bundle.

[0010] This wooden material made from mulberry core wood may be in the form of a pillar or a plate including a cavity formed near the center of the mulberry core wood, or may be in the form of a pillar or a plate cut out to avoid the cavity.

[0011] The wooden material made of this paper mulberry core material may be in the form of a pillar or a board, including a cavity formed in the middle of the paper mulberry core material, and the cavity may be filled with a filler material.

[0012] In this wooden material made from paper mulberry core, for example, the filler is at least one selected from the group consisting of hardening resin, hardening rubber, hardening adhesive, resin rod, metal rod, and rod of the same or different nature as the paper mulberry core.

[0013] The raw material for wooden products of the present invention, which has been made to achieve the above-mentioned object, is made from the wood material made from the mulberry core material, and is a raw material for any wooden product selected from wooden daily necessities, wooden stationery, wooden building materials, wooden furniture, wooden models, wooden crafts, and wooden toys.

[0014] The raw material for the wood product is preferably painted.

[0015] The wooden products of the present invention, which have been made to achieve the above-mentioned object, are formed from the raw materials for wooden products and are any one selected from the wooden daily necessities, wooden stationery, wooden building materials, wooden furniture, wooden models, wooden crafts, and wooden toys. [Effects of the Invention]

[0016] The wood material made from mulberry core material of this invention is made into pillars or boards, which broadens the uses of mulberry core material that has only been used for firewood and compost, and can be used as a raw material for various wood products. This wood material made from mulberry core material can be reused, which has the effect of reducing industrial waste and making effective use of resources.

[0017] This wooden material made from mulberry core not only fixes atmospheric CO2 in the plant using solar energy from mulberry cultivation, but also contributes to preventing global warming by suppressing greenhouse gas emissions caused by CO2 production when the mulberry core is incinerated after the bark, which is the raw material for Japanese paper, is harvested, and contributes to the SDGs (Sustainable Development Goals) by making effective use of industrial waste.

[0018] This wood material made from mulberry core has bending strength and paint properties equivalent to those of paulownia wood, a traditional high-quality material, and functions satisfactorily as a raw material for wood products. Furthermore, by filling the cavities that can form near the center of the mulberry core with a filler, it is possible to achieve even greater bending strength and compressive strength, improving its physical properties.

[0019] This wooden material made from mulberry core material can be used as a raw material for wooden products such as wooden daily necessities, wooden stationery, wooden fittings, wooden furniture, wooden models, wooden crafts, etc., either in the form of a column without being cut, or cut and cut into a column or board, or in the form of a single column or board, or by lining up and joining multiple columns or boards.

[0020] The raw material for wood products made from this wood material made from mulberry core has excellent bending strength and compressive strength, and can be beautifully painted to add value and used as a raw material for various wood products in the same way as conventional wooden raw materials.

[0021] Various wooden products made from such raw materials for wooden products, such as wooden household items, wooden stationery, wooden fittings, wooden furniture, wooden models, and wooden crafts, have smooth surfaces, bending strength and compressive strength almost equivalent to those of conventional wooden raw materials, and can be beautifully painted, making them highly versatile. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a perspective view showing an embodiment of a wooden material made of paper mulberry core to which the present invention is applied. [Figure 2] 1 is a plan view showing a process of manufacturing a wooden material made of paper mulberry core to which the present invention is applied. [Figure 3] FIG. 1 is a perspective view showing another embodiment of a wooden material made of paper mulberry core material to which the present invention is applied. [Figure 4] FIG. 1 is a perspective view showing another embodiment of a wooden material made of paper mulberry core material to which the present invention is applied. [Figure 5] FIG. 1 is a perspective view showing another embodiment of a wooden material made of paper mulberry core material to which the present invention is applied. [Figure 6] FIG. 1 is a perspective view showing another embodiment of a wooden material made of paper mulberry core material to which the present invention is applied. [Figure 7] 1 is a perspective view showing an example of a wooden product using a wooden material made of paper mulberry core to which the present invention is applied. [Figure 8] 1 is a graph showing the correlation between the air-dry specific gravity and bending strength of wood materials made from paper mulberry core to which the present invention is applied. [Figure 9] 1 is a graph showing the correlation between the air-dry specific gravity and bending strength of a wood material made of paper mulberry core to which the present invention is applied and that of ordinary wood. DETAILED DESCRIPTION OF THE INVENTION

[0023] Although the embodiments for carrying out the present invention will be described in detail, the technical scope of the present invention is not limited to these embodiments.

[0024] The wooden material 10 made of paper mulberry core material 1 of the present invention will be explained with reference to FIG. 1, and is formed of paper mulberry core material 1 and has a pillar or board shape.

[0025] Kozo trees grown in fields or upland fields grow to a maximum of approximately 6 m in a year, typically 1.5 to 5 m. They are then harvested and cut into lengths of 1 to 3 m, preferably 1 to 2 m, for easy processing. The bark is then peeled off and used as raw material for Japanese paper. The resulting core material 1, after the bark is removed, has a diameter of approximately 4 to 60 mm, typically 5 to 50 mm. A cavity may be observed near the center of the core material 1, but this often fills during the growth process. When cultivated for two or more years, kozo trees grow to a maximum diameter of approximately 70 mm, and the cavity near the center fills or only slightly remains. However, the bark tends to become too hard and unsuitable for use as a raw material for Japanese paper. For this reason, most cultivated kozo trees are harvested as a one-year-old. The mulberry core material 1 is dried naturally or by heating to remove excess moisture. If there is too much moisture, mold will grow, causing rot and discoloration.

[0026] 1(I), wooden material 101 made from paper mulberry core 1 may have a cavity 111 near the center that is either open or filled and crushed, and may be cut longitudinally in 1-3 m lengths, preferably 1-2 m intervals, with a diameter L1 of about 4-60 mm, preferably about 5-50 mm, and more preferably about 10-30 mm. However, if wooden material 101 is left in its roughly cylindrical shape from paper mulberry core 1, it will have various irregularities, such as uneven thickness, slight distortion of the cylindrical shape, or a misalignment of cavity 111, making it difficult to industrially or commercially obtain large quantities of smooth wooden material 101 with uniform thickness and length.

[0027] Therefore, as shown in Figure 1 (II), a wooden material 102 made from mulberry core material 1 may have a cavity 112 near the center that may remain open or be filled and crushed. It may be cut longitudinally at intervals of 1 to 3 meters, preferably 1 to 2 meters, and then cut and planed from a roughly cylindrical mulberry core material 1 with a diameter of approximately 4 to 60 mm, preferably approximately 5 to 50 mm, and more preferably approximately 10 to 30 mm, into a rectangular prism with a side length L2 of approximately 2.8 to 42 mm, preferably approximately 3.5 to 35 mm, and more preferably approximately 7 to 21 mm. However, compared to general-purpose building materials such as cedar and cypress, the presence of a cavity 112 near the center may cause a decrease in strength. Although not shown, such rectangular prisms can be obtained by sawing the mulberry core material 1, or by cutting it with a plane or planer, or by sawing it and then cutting it with a plane or planer.

[0028] Therefore, as shown in FIG. 1(III), the wooden material 103 made of the paper mulberry core material 1 is cut into lengths of 1 to 3 m, preferably 1 to 2 m, in the longitudinal direction, while avoiding the hollow 112 near the center. The rectangular columnar material 10 is cut and cut from the approximately cylindrical paper mulberry core material 1 having a diameter of about 4 to 60 mm, preferably about 5 to 50 mm, and more preferably about 10 to 30 mm, with a side length L3 of about 1.3 to 30 mm, preferably about 1.6 to 25 mm, and more preferably about 3.3 to 15 mm. 3a ~10 3d It may also be a product of As shown in Figure 2, such rectangular prism material is obtained by cutting out a rectangular prism-shaped piece from the mulberry core material 1 in the direction of the arrow AA, avoiding the cavity 113 near the center (see Figure 2(i)), then cutting the cut surface with a plane or planer in the direction of the arrow BB, and then sawing the piece parallel to the cut surface in the direction of the arrow B'-B', or cutting it with a plane or planer, or cutting it with a saw and then cutting it with a plane or planer (see Figure 2(ii)), and then sawing it perpendicular to the cut surface in the direction of the arrow CC and then cutting it with a plane or planer in the direction of the arrow C'-C' (see Figure 2(iii)), thereby obtaining a rectangular prism material 103 with a side length of L3.

[0029] Instead of forming the wooden material 10 made of the paper mulberry core material 1 into rectangular pillars 102-103, as shown in FIG. 1(IV), the wooden material 10 is cut into lengths of 1-3 m, preferably 1-2 m, in the longitudinal direction, while avoiding the hollow 112 near the center, and flat boards 10 including a hollow 114 near the center are cut from the approximately cylindrical paper mulberry core material 1 having a diameter of about 4-60 mm, preferably about 5-50 mm, more preferably about 10-30 mm. 4b and a flat plate material 10 that does not include the cavity 114. 4a 10 4c These plates 104 have a width L4 of about 2.8 to 42 mm, preferably about 3.5 to 35 mm, and more preferably about 7 to 21 mm, and a thickness W4 of 3 to 30 mm, preferably about 5 to 25 mm, and more preferably about 10 to 15 mm.

[0030] The wooden material 10 made from mulberry core material 1 is shown as an example of a quadrangular prism with a square cross section, but if necessary, it may be a triangular prism with a triangular cross section, preferably an equilateral triangle, or a hexagonal prism with a hexagonal cross section, preferably a regular hexagon (not shown).

[0031] As shown in Figure 3(I), a wooden material 10 made of mulberry core material 1 may be formed by arranging a plurality of columnar wooden pieces 102 in a row, face-to-face in the longitudinal direction, and joining them with wood glue, such as vinyl acetate emulsion, to form a wider, single-layer plank bundle. Alternatively, as shown in Figure 3(II), a plurality of columnar wooden pieces 102 may be arranged in multiple rows, such as four rows of four, with face-to-face in the longitudinal direction, and joined with wood glue to form a multi-layered, thicker plank bundle. Alternatively, as shown in Figure 3(III), a plurality of columnar wooden pieces 102 may be arranged in multiple layers and joined with wood glue to form a multi-layered, wider, thicker plank bundle. Instead of joining with wood glue, metal fittings such as bolts and nuts may be used for fastening.

[0032] When a wooden material 102 made from paper mulberry core 1 has a cavity 112 near the center as shown in Figure 4(I), it is preferably filled with a filler such as hardening resin, hardening rubber, hardening adhesive, resin rod, metal rod, or rod of the same or different material as the paper mulberry core. Filling the cavity 112 with a filler can increase the bending strength, tensile strength, and compressive strength of the wooden material 102 made from paper mulberry core 1, and can also prevent corrosion and mold caused by the intrusion of moisture or water.

[0033] For example, as shown in FIG. 1(II), wood bond 12, which is a curable adhesive, may be poured into cavity 112. Wood bond 12 is viscous and does not penetrate deep into the cavity simply by pouring it. Therefore, the lower end of cavity 112 may be closed with a cap, a wood bond injection tube may be inserted from the upper end to the lower end, and the wood bond may be injected while being slowly withdrawn, thereby filling the entire cavity 112 with wood bond. Instead of a curable adhesive, a curable resin material or a curable rubber material may be poured and cured.

[0034] Alternatively, as shown in Figure 1(III), a filler 13 may be inserted into the cavity 112. A rod of the same material as the mulberry core material 1 may be pushed in as a companion piece to the filler 13, and may be joined with wood glue, a hardening adhesive, as needed. Instead of a rod of the same material as the mulberry core material 1, a rod of wood of a different material to the mulberry core material may be pushed in as the filler 13, or a resin rod or a metal rod such as metal wire may be pushed in. In either case, they may be joined with wood glue, a hardening adhesive, as needed. Alternatively, as shown in Figure 1(IV), a metal screw rod 14 may be screwed in and pushed in.

[0035] The wooden material 10 made of paper mulberry core material 1 is a wooden material 102 in which the cavities 112 obtained as shown in FIG. 4 are filled with a filler, or a wooden material 10 in which the cavities 113 are avoided as shown in FIG. 1(III). 3a ~10 3d A plurality of such columnar single materials may be arranged and joined in a single layer or multiple layers as shown in Figures 5(I) to (III) to form a columnar bundle with a larger diameter, or a plate-like bundle with a wider area or thicker layers.

[0036] The wooden material 10 made of paper mulberry core material 1 is a wooden material 10 as shown in FIG. 4a ~10 4c A plurality of such plate-like single materials may be arranged and joined in multiple layers as shown in Figure 6(I) to form a columnar bundle with a larger diameter, or may be arranged and joined alternately in multiple layers as shown in the same figure (II) to form a wider and thicker plate-like bundle.

[0037] The wooden material 10 made from mulberry core material 1 has been described as being in the form of a pillar or board, but the pillar or board shape may be further cut into blocks such as lottery blocks (see Figure 6 (III)), rectangular blocks (see Figure 6 (IV)), cubic blocks (see Figure 6 (V)), rhombic hexahedrons (see Figure 6 (VI)), rhombic dodecahedrons (not shown), and cylindrical blocks (see Figure 6 (VII)).

[0038] The wooden material 10 made from the mulberry core material 1 is a raw material for wooden products such as wooden tableware such as trays, spoons, forks, plates, and chopsticks, wooden daily necessities such as storage boxes and key chains; wooden stationery such as pen holders, bookends, and pencil cases; wooden fittings such as shoji lattices, doors, sliding doors, and transoms; wooden furniture such as chairs and tables; wooden models and parts thereof such as architectural models and building models; wooden crafts such as building blocks and marquetry; and wooden toys.

[0039] Wood products made from such raw materials for wood products are light and strong, have a smooth surface that feels good to the touch, and are highly versatile.

[0040] An example of such a wooden product is a round chair 20 as shown in Figure 7. The seat board 21 is made by cutting a plate-like bundle as shown in Figure 6(II) into a disk shape. A seat frame (not visible in Figure 7) formed from a plate-like bundle as shown in Figure 3(III) or Figure 6(III) is arranged in a cross shape on the back side of the seat board 21 and screwed in place. Four legs 23 formed from column-like bundles as shown in Figure 1(II), Figure 3(II), or Figure 5(II) are attached to the seat frame. Mortises are drilled into the seat frame and the tenons of the legs 23 are inserted into them. Opposite pairs of the four legs 23 are connected by tenons 24 formed from column-like bundles as shown in Figure 1(II), Figure 3(II), or Figure 5(II). Mortises are drilled into the legs 23 and the tenons of the tenons of the tenons 24 are pressed into them. The two tenons are joined by a half joint. The tenons and mortises may be reinforced by bonding with wood glue.

[0041] Although a round chair has been used as an example of the wooden product, other wooden products can be produced in the same manner. [Example]

[0042] Examples to which the present invention is applied and comparative examples to which the present invention is not applied will be described in detail below.

[0043] (Preparation Example 1: Preparation of raw wood material made from paper mulberry core) The raw material for the wood material made from mulberry core material of the present invention was purchased from mulberry trees cultivated as so-called one-year-old trees at Clean Agri Co., Ltd., where the bark had been peeled off and then the mulberry core material was naturally dried. This raw material had a cavity in the center.

[0044] (Moisture measurement test: measuring the moisture content of raw paper mulberry core material) Three specimens of mulberry core wood, approximately 1.8 m in length, were divided into three pieces approximately 60 cm long, and the moisture content of the base, middle, and tip of each piece was measured as follows. The moisture content is the proportion of water contained in a sample and is expressed by the following formula (1). W = (W1 - W0) / W0) × 100 (1) (In formula (1), W is the moisture content to be determined, W1 is the weight before measurement, and W0 is the absolute dry weight when the sample is dried at 105 ± 2°C and reaches a constant weight (the difference in mass between two consecutive measurements dried at 105 ± 2°C does not exceed 0.1% of the sample mass before drying. However, the drying time from the second time onwards must be at least half of the initial drying time).) The moisture content of the specimens after storage was measured in accordance with the JIS P8203:2010 bone dry method. The bone dry method is outlined below. The specimen is dried at a temperature of 105°C ± 2°C, and this process is repeated until a constant weight is reached. The mass is measured and compared with the mass of the specimen before and after drying to calculate the moisture content using formula (1). The moisture content is expressed as a percentage. The results are shown in Table 1.

[0045] [Table 1]

[0046] As is clear from Table 1, the average moisture content of the nine measured locations was 10.44%. According to the JAS standard (established on August 29, 2007; Ministry of Agriculture, Forestry and Fisheries Notification No. 1083), the moisture content standard for dried lumber for building structures and lumber for finishing purposes is 20% or less, and 15% or less for finishing materials. Additionally, there are additional considerations to be taken when applying a paint finish to furniture materials. Because wood shrinkage can cause the surface to crack, the moisture content required during processing varies depending on the application and location. For example, in Japan, the moisture content for general household furniture is 9-14%, while that for general building materials is 15-22% (Compiled by the Polytechnic University Infrastructure Development Center, 2017). The moisture content measurements of the raw mulberry heartwood in this study showed a minimum of 10.13%, a maximum of 10.73%, and an average of 10.44%, meeting the 9-14% level required when processing general household furniture materials. Therefore, mulberry heartwood is deemed suitable for use in general household furniture.

[0047] (Preparation Example 2: Preparation of wood material made from paper mulberry core (Part 1)) A section of the raw wood material made from mulberry core wood obtained in Preparation Example 1, measuring approximately 25 mm square or larger in length and width (x-axis, y-axis directions), was used. This was then shaved using an automatic planer to have a square cross section, finished to a 16.5 mm square, and cut to a length of 264 mm, resulting in 23 pieces that were used as columnar specimens (see Figure 1 (II)).

[0048] (Test Example 2: Measurement of air-dry specific gravity) The air-dry specific gravity of wood is the specific gravity of wood when it reaches its air-dry moisture content, or more formally, the specific gravity at the standard moisture content or normal moisture content, and is the standard specific gravity of wood for various material tests. The air-dry moisture content is the moisture content when wood is in a normal atmosphere and its moisture content has reached equilibrium (approximately 13-18%), but in Japan, the standard moisture content is conveniently set at 15%. The air-dry specific gravity is the weight of the specimen when it is naturally dried (water content: approximately 15%) divided by the volume measured from the dimensions of the three sides of the specimen. The results are shown in Table 2. The average air-dry specific gravity is 0.250 g / cm 3 It was.

[0049] (Test Example 3: Bending Strength Test) The bending strength was measured on 23 specimens in accordance with JIS Z2101:2009. The results are shown in Table 2. The average bending strength was 26.60 N / mm 2 The correlation between air-dry specific gravity and bending strength is shown in Figure 8.

[0050] [Table 2]

[0051] For reference, Table 3 shows a comparison of the air-dry specific gravity and bending strength of ordinary wood, which has a legend in "Japanese Domestic Wood (compiled by the Japan Wood Processing Technology Association Business Committee, 1984)," and the wooden material made from paper mulberry core material in Preparation Example 2. The distribution is also shown in Figure 9.

[0052] [Table 3]

[0053] As is clear from Figure 9, a positive correlation is observed between the air-dry specific gravity and bending strength of general wood, which follows an approximate straight line. Wooden materials made from mulberry core follow this approximate straight line, showing similar behavior to general wood. Wooden materials made from mulberry core have air-dry specific gravity and bending strength that are roughly equivalent to those of kiri (Paulownia), indicating that, like kiri, they can be used for a variety of wooden products, including furniture such as chests of drawers.

[0054] (Preparation Example 3: Preparation of wood material made from paper mulberry core (Part 2)) The raw wood material made from mulberry core wood obtained in Preparation Example 1 was cut to a length of approximately 200 mm, and then, as shown in Figure 2, was cut into a kamaboko shape using a saw in the direction of the arrow AA, avoiding the cavity 113 near the center (Figure 2(i)). Next, the cut surface was cut with a planer in the direction of the arrow BB, and the rectangular pillar material was cut parallel to the cut surface in the direction of the arrow B'-B' using a planer so that the length of one side of the rectangular pillar material (Figure 1(III)) was 10 mm (Figure 2(ii)). Next, the raw wood material was cut perpendicular to the cut surface in the direction of the arrow CC, and then cut with a circular plane in the direction of the arrow C'-C' and cut with a planer so that the cross section was a square with sides of 10 mm (see Figure 2(iii)). Five specimens of wooden material 103 were obtained as rectangular pillar material with sides of 10 mm. The initial weight, length, height, and width of the test specimen were measured, and the bone dry weight, air-dry specific gravity, and moisture content were measured in the same manner as in Preparation Example 2. The results are shown in Table 4. Furthermore, the bending strength of the test specimens was measured in the same manner as in Preparation Example 2. The results are shown in Table 5. The correlation between air-dry specific gravity and bending strength is also shown in Figure 8. Table 6 shows a comparison of the average air-dry specific gravity and the average bending strength for Preparation Examples 2 and 3.

[0055] [Table 4]

[0056] [Table 5]

[0057] [Table 6]

[0058] The air-dry specific gravity and bending strength of Preparation Examples 2 and 3 are compared in terms of bending strength per unit specific gravity. Bending strength (N / mm 2 )÷Air-dry specific gravity (g / cm 3 ) is calculated as follows: In Preparation Example 2, the ratio is 26.60 / 0.250=106.40, whereas In Preparation Example 3, 37.62 / 0.297=126.66, so The ratio was 126.66 / 106.40=1.19=119%, an increase of approximately 20%. As is clear from Tables 4, 5, and 6, as well as Figure 8, Preparation Example 3 has a higher bending strength per unit air-dry specific gravity than Preparation Example 2. The reason for this is not entirely clear, but it is presumed that in Preparation Example 2, the wooden material made from mulberry core has cavities and is therefore less able to resist bending, whereas in Preparation Example 3, the wooden material made from mulberry core has no cavities and is therefore able to resist bending sufficiently, and that the higher specific gravity results in a higher bending strength that follows the approximate curve shown in Figure 8.

[0059] (Preparation Example 4: Preparation of wood material made from paper mulberry core (Part 3)) The wooden material made of paper mulberry core prepared in the same manner as in Preparation Example 3 was painted to give a finish. The paints used are four types: bamboo ink, tung oil, water-based urethane, and new lacquer, with the physical properties shown below. (1) Bamboo Ink (Manufacturer: Taketora Co., Ltd.) The main ingredients are bamboo charcoal, water, tourmaline, seaweed-derived glue, and bamboo vinegar. The finish is matte black, but to achieve a jet black finish, it requires at least three coats with a brush. It has deodorizing, absorbing, humidity-regulating, and insulating properties. Drying time is 10 to 30 minutes at 20°C. (2) Tung oil (manufacturer: Yamakei Sangyo Co., Ltd.) This oil is extracted from the seeds of the tung tree. When applied to wood, it creates a hard coating and is weather-resistant, making it suitable for use on exterior materials. Among drying oils, it produces a particularly deep color and a hard coating. The drying time for multiple coats is approximately 12 hours at 20°C, and it takes approximately 2 to 3 weeks for complete hardening. (3) Water-based urethane / Aclex (manufacturer: Wasin Chemical Industry Co., Ltd.) This is a water-based paint made by dissolving synthetic resins in water. It does not contain any flammable compounds, so it has little odor. It creates a strong coating film with excellent chemical resistance and thickness. It takes 4 hours to harden at 20°C. (4) Shin Urushi (Manufacturer: Sakurai Fishing Tackle Co., Ltd.) This one-component resin is extracted from cashew nut shells and has a texture similar to that of real lacquer, making it a plant-based paint that does not cause irritation and does not require any special care. It is oil-resistant and has excellent resistance to alkalis, acids, water, and heat. It takes approximately 24 hours at 20°C to dry for one coat to fully harden.

[0060] Test specimens of a size conforming to the JIS Z2101:2009 test standard were painted in three coats: primer, intermediate coat, and finish. For comparison, unpainted specimens were used. As a result of the painting test on wooden materials made from paper mulberry core, no particular differences were observed in brush spread or drying compared to general wood. Furthermore, the finish on all test specimens was beautiful and there were no particular problems.

[0061] (Preparation Example 5: Preparation of wood material made from paper mulberry core (Part 4)) When a strip-shaped kozo-core wood strip like the one shown in Figure 6(III) was inserted into the cavity of the kozo-core wooden material obtained in Preparation Example 2 and fixed with a commercially available wood glue (vinyl acetate emulsion adhesive), a kozo-core wooden material was obtained in which the cavity defect was eliminated. The obtained kozo-core wooden material exhibited physical properties approximately equivalent to those of the kozo-core wooden material obtained in Preparation Example 3.

[0062] (Example 1: Preparation of a round chair) A round chair 20 shown in Figure 7 can be produced as a wooden product. The seat 21 is made by bundling rectangular mulberry-core wooden materials, as shown in Figures 1(II) and 4(II), with commercially available wood glue (vinyl acetate emulsion adhesive) into plates as shown in Figure 3(III), and then cutting them into a disk. A seat frame, formed from plate bundles as shown in Figures 3(III) and 6(III), is attached in a cross shape to the underside of the seat 21 and screwed into place. Four legs 23, formed from rectangular mulberry-core wooden materials as shown in Figures 1(II) and 5(II) with wood glue, are attached to the seat frame. Mortises are drilled into the seat frame, and the tenons of the legs 23 are inserted and fixed with wood glue. Opposing pairs of the four legs 23 are connected with beams formed from beams. Mortises are drilled into the legs 23, and the tenons of the beams are inserted into them. The two crosspieces are joined by a notched joint, thereby creating the round chair 20.

[0063] As explained in detail above, the air-dry specific gravity and bending strength values ​​obtained from bending strength tests of wood materials made from mulberry core to which the present invention is applied indicate that the mulberry core has the same strength as paulownia. During the manufacturing process of this wood material made from mulberry core, various manual cutting and mechanical processing were performed without any problems. Therefore, mulberry core, which has not been effectively utilized until now, can be used as a material with bending strength comparable to paulownia. In particular, due to its extremely light air-dry specific gravity compared to other common woods, it has the potential to be applied to end products such as wood products as a wood-based material with unprecedented performance.

[0064] Furthermore, while mulberry core wood may have a cavity near the center, in most cases this is not considered a major problem as the cavity fills up during the growth process. Even if a cavity remains, it can be filled with so-called filler wood (also known as companion wood, preferably wood of the same species) to eliminate the cross-sectional defect and / or cavity defect. It has been confirmed that wood glue (vinyl acetate emulsion adhesive) can be used to glue the filler wood.

[0065] Regarding painting wooden materials made from mulberry core, it was confirmed that it was possible to paint beautifully using the same process as for general wood with four different types of paints, each with different physical properties: water-based bamboo ink, oil-based tung oil, water-based urethane made from synthetic resin, and new lacquer made from natural resin, and there were no problems with the finish, so it was confirmed that they can be treated the same as general wood.

[0066] In the examples, the raw mulberry core material was naturally dried before use, but it can be stored in a well-ventilated environment to prevent mold growth. Specifically, the mulberry core material was stored in an indoor storehouse attached to the workshop, just like other wood, and observed for mold growth for one year, but no mold growth was observed. If storage in an environment prone to mold growth is anticipated, painting the wooden material made from mulberry core material to protect the surface as described above will prevent the cellulose and starch contained in the mulberry core material from being exposed, thereby preventing mold growth. [Industrial Applicability]

[0067] The wooden material made from the paper mulberry core of the present invention can be used as a raw material for wooden crafts such as wooden daily necessities, wooden stationery, wooden fixtures, wooden furniture, wooden models, etc. [Explanation of symbols]

[0068] 1 is mulberry core material, 10·101·102·103·10 3a 10 3b 10 3c 104 10 4a 10 4b 10 4c is a wooden material made from mulberry core, 111, 112, 113, and 114 are hollow, 12 is wood glue, 13 is wood filler, 14 is a metal screw rod, 20 is a wooden round chair, 21 is a seat, 23 is a leg, and 24 is a crosspiece.

Claims

1. A wooden material made of mulberry core material, characterized in that it is formed from mulberry core material and is in the shape of a pillar, board, or block.

2. The wooden material made from mulberry core material as described in claim 1, characterized in that a plurality of the columnar, plate-shaped, or block-shaped single materials are arranged and joined in a single layer or multiple layers to form a columnar bundle with a larger diameter, a wider or thicker plate-shaped bundle, or a larger block-shaped bundle.

3. A wooden material made from mulberry core wood as described in claim 1, characterized in that the pillar-shaped, plate-shaped, or block-shaped material includes a cavity formed in the middle of the mulberry core wood, or the pillar-shaped, plate-shaped, or block-shaped material is cut out to avoid the cavity.

4. The wooden material made from mulberry core material according to claim 1, characterized in that the pillar-shaped, plate-shaped, or block-shaped material includes a cavity formed near the center of the mulberry core material, and the cavity is filled with a filler material.

5. The wooden material made from mulberry core material according to claim 4, characterized in that the filler is at least one selected from the group consisting of hardening resin, hardening rubber, hardening adhesive, resin rod, metal rod, and rod of the same or different nature as the mulberry core material.

6. A raw material for any wooden product selected from wooden daily necessities, wooden stationery, wooden fittings, wooden furniture, wooden models, wooden crafts, and wooden toys, comprising a wooden material made from the mulberry core material according to any one of claims 1 to 5.

7. 7. The raw material for wood products according to claim 6, characterized in that it is painted.

8. A wooden product formed from the raw material for wooden products according to claim 6, characterized in that the wooden product is any one selected from the group consisting of wooden daily necessities, wooden stationery, wooden fittings, wooden furniture, wooden models, wooden crafts, and wooden toys.

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