Round bamboo material and its self-coloring and self-finishing drying method and equipment

Abstract

The present application relates to the technical field of bamboo processing products, and provides a round bamboo material and a drying method and equipment capable of self-coloring and self-finishing, the round bamboo material comprising a bamboo cylinder and a protective coating layer covering the outer surface of the bamboo cylinder, the protective coating layer being waxiness originally on the surface of the bamboo cylinder, the protective coating layer being present on the surface of the bamboo cylinder everywhere, the roughness value of the protective coating layer being 0.8-2.1 microns; the moisture content of the bamboo material being 6-16%. The round bamboo material uses the waxiness originally on the round bamboo as the protective coating layer, thereby having high surface hardness, and the protective coating layer is flat and even on the surface of the bamboo cylinder, and has relatively high adhesion to the surface of the bamboo cylinder.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bamboo processing products, in particular to a round bamboo material, and also relates to a drying method and equipment for obtaining the round bamboo material, wherein the drying method can simultaneously complete coloring and finishing of the round bamboo during the drying process of the round bamboo, and the coloring and finishing are spontaneously completed. BACKGROUND

[0002] Bamboo is a kind of abundant biomass material, which has a wide distribution range, a fast growth speed and is green and environmentally friendly. In China, the bamboo product industry is a green and rich people's industry with great vitality and potential, which plays an important role in promoting the development of circular economy and the realization of the double carbon strategy. Bamboo has a wide range of uses, such as processing bamboo into reconstituted bamboo for outdoor flooring, and processing some small-diameter bamboo into bamboo handicrafts, bamboo toothpicks, bamboo chopsticks, etc. Among them, round bamboo products also have a wide application space. Round bamboo is simple to process, can maximize the preservation of the characteristics of bamboo itself, and can be widely used in indoor and outdoor furniture, large-span buildings, bamboo structure buildings, etc.

[0003] Fresh round bamboo includes a bamboo tube and a bamboo joint, and the tube wall of the bamboo tube includes, from the outside to the inside, a bamboo green, a bamboo flesh and a bamboo yellow, and the surface of the bamboo green is attached with a layer of wax. The existing technology considers that the wax is easy to separate and fall off during processing, and the existence of the wax also affects the adhesion of the paint finish layer on the surface of the round bamboo, so the wax is usually removed, and the green and yellow are also removed in some cases.

[0004] For example, a round bamboo processing method disclosed in an invention patent application with the publication number CN111940264A and the title of "Decorative Round Bamboo and Manufacturing Method" overcomes the above problems through drying, surface treatment and other means to improve the decorative effect and durability of the round bamboo. Specifically, the inner joint of the round bamboo is punched and dried, the flexible sanding or sandblasting process is used to uniformly remove the wax layer on the surface of the round bamboo, the waterproof coating, the aging-resistant coating, the mildew-resistant coating, the decorative coating and the light-resistant layer are sprayed on the surface of the round bamboo from which the wax has been removed, and finally the paint layer is dried and solidified.

[0005] For another example, a bamboo processing method disclosed in an invention patent application with the publication number CN109227839A and the title of "Bamboo Drying and Heat Treatment Method" uses polyethylene wax modified paraffin as a medium to dry and heat treat the round bamboo. The low molecular weight modified paraffin penetrates into the vascular bundle of the bamboo, replaces the water and realizes fast drying; in addition, under the action of the high-temperature modified paraffin, the organic substances such as hemicellulose, sugar and starch in the cell wall of the bamboo are degraded to form a pore structure, and the modified paraffin can enter the cell wall structure and play a physical filling and reinforcing role after cooling and solidification. After the modification treatment, the equilibrium moisture content of the round bamboo is reduced to 2.5%, and the elastic modulus is increased by 12%.

[0006] In fact, the natural wax coating of round bamboo is a high-quality natural wax that serves to isolate the bamboo from external moisture exchange and prevent pests and diseases. Natural waxes have advantages that chemically synthesized waxes cannot match. Currently available commercially available natural waxes can only be obtained from a few plant species, and the natural wax coating of round bamboo is one of them. Therefore, the current process of first removing the natural wax coating of round bamboo and then re-coating paraffin wax onto the bamboo tube surface not only wastes the natural wax coating but also makes the processing of round bamboo complex and lengthy, increases production costs, and carries the risk of environmental pollution from the use of industrial paraffin wax. Summary of the Invention

[0007] The technical objective of this invention is to overcome at least one of the aforementioned technical problems and provide a round bamboo material that uses the original wax of the round bamboo as a protective coating, thereby achieving high surface hardness. Furthermore, the protective coating flows smoothly and evenly on the surface of the bamboo tube, adhering firmly to the surface. This invention also provides a round bamboo drying method that can complete the drying, recoating, and coloring of round bamboo in one step without using dyes, paints, or protective coatings. This results in a round bamboo material with a moisture content meeting usage requirements, decorative color, and a protective surface coating. This simplifies the processing technology of round bamboo, improves production efficiency, reduces production costs, and fully utilizes round bamboo resources, achieving comprehensive and all-round utilization of round bamboo. This invention further provides a round bamboo drying device.

[0008] To achieve the above-mentioned technical objectives, the first aspect of the present invention provides a round bamboo material, which includes a bamboo tube and a protective coating covering the outer surface of the bamboo tube. The protective coating is the original wax on the surface of the bamboo tube, and the protective coating is applied to all parts of the surface of the bamboo tube. The roughness value of the protective coating is 0.8~2.1μm. The moisture content of the round bamboo is 6~16%.

[0009] As a preferred embodiment, the protective coating has a pencil hardness test value higher than 4H and can withstand at least 120 tape peel tests.

[0010] In a preferred embodiment, the lightness value of the round bamboo is 26.9~31.2, the red-green index is 4.9~5.9, and the yellow-blue index is 9.6~12.9.

[0011] In one preferred embodiment, the round bamboo material is moso bamboo, green bamboo, hemp bamboo, or small-leaf bamboo.

[0012] In one preferred embodiment, the round bamboo material comprises a plurality of bamboo tubes, with adjacent bamboo tubes separated by bamboo nodes.

[0013] The second aspect of the present invention provides a method for drying round bamboo that is capable of self-coloring and self-coating, wherein the round bamboo includes a bamboo tube and the outer surface of the bamboo tube is covered with wax; during drying, the temperature of the drying medium is 60~100℃, the relative humidity is 30~80%RH, and the flow rate is 2~8m / s.

[0014] In a preferred embodiment, the temperature of the drying medium is 80~90℃, the relative humidity is 65~75%RH, and the flow rate is 3~5m / s.

[0015] In a preferred embodiment, after drying, a round bamboo material with a moisture content of 6-16% is obtained. The round bamboo material includes a bamboo tube and a protective coating covering the outer surface of the bamboo tube. The protective coating is the original wax on the surface of the bamboo tube. The protective coating is applied to all parts of the surface of the bamboo tube. The roughness value of the protective coating is 0.8-2.1 μm.

[0016] As a preferred implementation, the complete shape of the bamboo joints is preserved at least before drying.

[0017] A third aspect of the present invention provides a round bamboo drying device capable of self-coloring and self-coating, comprising a drying chamber, wherein a heat source, a moisture source, a fan, and a material stacking rack are provided in the drying chamber;

[0018] The material stacking rack includes a frame, wheels at the bottom of the frame, and multiple layers of partitions installed in a drawer-like manner on the frame;

[0019] The frame includes a vertical beam, a base frame connecting the vertical beam, and at least one pair of horizontal beams installed through the vertical beam, with guide wheels provided on the horizontal beams;

[0020] The partition includes a pair of horizontal plates, an end plate fixedly connected to the first end of the pair of horizontal plates, and a tail plate movably connected to the end of the pair of horizontal plates. Multiple first limiting rods are spaced apart on the inner side of the end plate, and multiple second limiting rods are spaced apart on the inner side of the tail plate. The first limiting rods and the second limiting rods correspond one-to-one.

[0021] In a preferred embodiment, the two ends of the tail plate are respectively hinged to the ends of a pair of horizontal plates. When the tail plate is flipped to a state corresponding to the end plates, it is fixedly connected to the horizontal plates by a locking structure.

[0022] In a preferred embodiment, the inner side of the crossbar is provided with a movable groove, which is arranged along the length direction of the crossbar. The partition also includes a support plate, the two ends of which are inserted into the movable groove and can move within the movable groove. The top surface of the support plate is at least lower than the bottom surface of the crossbar.

[0023] In a preferred embodiment, the drying equipment further includes a limiter, which includes a pair of positioning rods and an auxiliary limiting member connecting the pair of positioning rods. The positioning rods have positioning grooves along their length, and the positioning grooves are through grooves. The auxiliary limiting member includes arc grooves that correspond one-to-one with the first limiting rods. Multiple movable rollers are provided on the inner wall of the arc grooves, and the roller shafts of the movable rollers are arranged perpendicular to the axial direction of the arc grooves.

[0024] In summary, the round bamboo material disclosed in this invention application uses the original wax of round bamboo as a protective coating, thereby achieving high surface hardness and smoothness, and the protective coating is firmly adhered to the surface of the bamboo tube.

[0025] This invention discloses a self-coating and self-coloring method for drying round bamboo. This method completes the drying, recoating, and coloring of round bamboo in one step without using dyes, paints, or protective coatings. The result is round bamboo material with a moisture content meeting usage requirements, decorative color, and a protective surface coating. This simplifies the processing of round bamboo, improves production efficiency, reduces production costs, and fully utilizes round bamboo resources, achieving comprehensive utilization. Furthermore, when the temperature range is 80-90℃, the original wax on the bamboo surface has good fluidity during the drying process, resulting in a protective coating with high smoothness (low roughness) and good adhesion. Additionally, when the airflow velocity ranges from 2 to 8 m / s, the original wax on the bamboo surface has good fluidity during the drying process, preventing agglomeration and peeling, and ensuring a high surface smoothness (low roughness) of the protective coating.

[0026] This invention discloses a self-coating and self-coloring round bamboo drying device. First, by using the limiting rod of the partition, the round bamboo can only undergo minimal displacement while separating two layers of bamboo. Furthermore, the limiting rod inserts into the opening of the bamboo tube without contacting it, thus preventing any impact on the leveling and curing of the original wax on the bamboo tube surface. Second, the coordinated arrangement of the movable groove and the movable short rod allows the support rod to move to a certain extent along the length of the crossbar to adjust its position. This ensures the support rod is always supported at the bamboo node, preventing contact between the support rod and the bamboo tube surface and thus avoiding any impact on the leveling and curing of the original wax at the contact point. Finally, the hinged assembly of the tail plate and the crossbar allows the tail plate to be opened, enabling the round bamboo to be fed into the device from the tail end of the partition, improving feeding efficiency. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a self-coloring and self-coating round bamboo drying device according to an embodiment of this application.

[0029] Figure 2 This is a schematic diagram of a material stacking rack according to an embodiment of this application.

[0030] Figure 3 This is a schematic diagram of the structure of a frame according to an embodiment of this application.

[0031] Figure 4 This is a schematic diagram of a partition structure according to an embodiment of this application.

[0032] Figure 5 for Figure 4 A magnified view of a portion of point A in the middle.

[0033] Figure 6 This is a schematic diagram of a limiter according to an embodiment of this application.

[0034] Figure 7 This is a schematic diagram illustrating the cooperation between the limiter and the partition in an embodiment of this application.

[0035] Figure 8 This is a schematic diagram of another structure of the partition according to an embodiment of this application.

[0036] Figure 9 This is a schematic diagram of the structure of round bamboo prepared by the drying method of this application embodiment.

[0037] Figure 10 The images show the round bamboo materials used in Examples 2, 6, and 12 of this application, as well as the round bamboo materials used in Comparative Examples 1 to 5.

[0038] Figure 11 (a) are photographs of the round bamboo materials of Examples 2, 6, and 12 of this application before and after the surface pencil hardness test; (b) are photographs of the round bamboo materials of Examples 2, 6, and 12 of this application after the tape peeling test.

[0039] In the above diagram: 1. Drying chamber, 2. Heat source, 3. Humidity source, 4. Fan, 5. Material stacking rack, 6. Detection unit, 7. Round bamboo, 51. Frame, 52. Traveling wheel, 53. Partition, 511. Vertical frame beam, 512. Bottom frame, 513. Horizontal frame beam, 514. Guide wheel, 515. Limiting baffle, 531. Horizontal plate, 532. End plate, 533. Tail plate, 534. Screw system, 535. First limiting rod, 536. Second limiting rod, 537. Movable groove, 538. Support plate, 71. Bamboo green layer, 72. Bamboo flesh layer, 73. Bamboo yellow layer, 74. Protective coating, 81. Positioning rod, 82. Auxiliary limiting component, 811. Positioning groove, 821. Arc groove, 822. Movable roller. Detailed Implementation

[0040] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0041] Example: Refer to Figure 1 The above describes a round bamboo drying device capable of self-coloring and self-coating. It includes a drying chamber 1, and a heat source 2, a moisture source 3, a fan 4, a material stacking rack 5, and a detection unit 6 installed in the drying chamber 1.

[0042] The drying chamber 1 is any of the existing chambers that can provide a drying space, such as a kiln-type drying chamber or an aluminum alloy drying chamber.

[0043] The heat source 2 is an existing electric heat source, oil heat source, or other existing system capable of heating the drying medium. Preferably, it is located in the upper part of the drying chamber 1, and is separated into an upper heating space and a lower drying space by a baffle plate. The heating space and the drying space are connected by an air duct formed by the gap between the baffle plate and the inner wall of the drying chamber 1.

[0044] The moisture source 3 is a conventional steam spraying system, such as including a steam nozzle, a pipeline connected to the steam nozzle, and a steam source, which is suitable for controlling the relative humidity of the drying medium in the drying chamber 1.

[0045] The fan 4 is an existing axial flow fan, which is located at the top of the drying chamber 1 and on one side of the heat source 2. Driven by the fan 4, the drying medium circulates within the drying chamber 1 in a specific flow path. If the position of the fan 4 is set as the starting point of the flow path of the drying medium, preferably, the moisture source 3 is located near the end point of the flow path.

[0046] The detection unit 6 is of the prior art and includes, for example, a dry bulb thermometer and a wet bulb thermometer provided on one side of the drying chamber 1.

[0047] Refer to Figure 2 , Figure 3 As shown in

[0048] The rack body 5 is a metal frame structure of the prior art. The rack body 5 includes vertical rack beams 511, a rectangular bottom frame 512 welded to connect the vertical rack beams 511, and at least a pair of horizontal rack beams 513 installed through the vertical rack beams 511. The traveling wheels 52 are universal wheels of the prior art, and they are screwed and installed on the bottom surface of the bottom frame 512 so that the material stack rack 5 can be easily pushed. Guide wheels 514 are screwed and installed on the horizontal rack beams 513, and a plurality of guide wheels 514 are arranged at intervals along the length direction of the horizontal rack beam 513, and the setting direction of their installation shafts is perpendicular to the length direction of the horizontal rack beam 513. A limit baffle 515 is welded and provided at the end of the horizontal rack beam 513 in the length direction.

[0049] Refer to Figure 4 As shown in

[0050] The cross plates 531 are in a "冂" shape and can cooperate with the guide wheels 514 to guide and urge the partition plate 53 into the support space formed by the horizontal rack beams 513.

[0051] Refer to Figure 5 As shown in

[0052] Specifically, a plurality of first limiting rods 535 are welded and arranged at intervals on the inner side surface of the end plate 532, and a plurality of second limiting rods 536 are welded and arranged at intervals on the inner side surface of the tail plate 533, and the first limiting rods 535 and the second limiting rods 536 correspond to each other one by one. In other words, when the tail plate 533 is flipped to a state corresponding to the end plate 532, that is, when the tail plate 533 is vertically arranged, it is fixedly connected to the cross plate 531 through a locking structure. In this embodiment, the locking structure is the screw system 534, which is a combination of a screw and a nut of the prior art.

[0053] In use, flip the tail plate 533 to a horizontal position, and insert the head end of each round bamboo 7 into the first limiting rod 535 one by one. After all the first limiting rods 535 are fitted with round bamboo 7, flip the tail plate 533 to a vertical position so that the second limiting rod 536 is inserted into the end of the round bamboo 7, and tighten the screw system 534. Then, push the partition 53 that has been loaded into the support space formed by the horizontal frame beams 513 through the guide wheel 514 until the end face of the end plate 532 contacts the limiting baffle 515. Finally, repeat the above until each layer of horizontal frame beams 513 has a partition 53, thus completing the loading of the entire material stack rack 5. At this time, the two ends of the round bamboo 7 are suspended by the first limiting rod 535 and the second limiting rod 536. During the drying process, the round bamboo 7 is suspended and placed without contact with the outer surface of the round bamboo 7. Therefore, the drying process will not damage the original wax of the round bamboo 7, and will not affect the color change reaction of the surface of the round bamboo 7, as well as the leveling and curing of the wax.

[0054] As a preferred embodiment, refer to Figure 6 As shown, the drying equipment also includes a limiter, which includes a pair of positioning rods 81 and multiple auxiliary limiting components 82 connected to the pair of positioning rods 81 by welding. The positioning rods 81 are metal components with positioning grooves 811 along their length direction, and the positioning grooves 811 are through grooves. The auxiliary limiting components 82 include arc grooves 821 that correspond one-to-one with the first limiting rods 535. The axial direction of the arc grooves 821 is parallel to the length direction of the positioning grooves 811, and multiple (e.g., 3) movable rollers 822 are screwed onto the inner wall of the arc grooves 821. The roller shafts of the movable rollers 822 are arranged perpendicular to the axial direction of the arc grooves 821.

[0055] Reference Figure 7 As shown, the horizontal plate 531 of the partition 53 is placed in the positioning groove 811. The round bamboo 7 is aligned with the first limiting rod 535 via the rolling conveying surface formed by the three movable rollers 822, and one end of the bamboo 7 is inserted into the first limiting rod 535. After all the round bamboo 7 have been loaded, the partition 53 is removed from the limiting device and then sent into the frame 51. The limiting device enables the loading of the round bamboo 7 quickly and efficiently. And because the movable rollers 822 form a rolling conveying surface, the loading process will not damage the original wax on the surface of the round bamboo 7.

[0056] As a preferred implementation method, refer to Figure 8As shown, the partition 53 also includes a support plate 538 connecting a pair of horizontal plates 531 in the middle. Preferably, there is one support plate 538, and the top surface of the support plate 538 is at least lower than the bottom surface of the horizontal bar 531. Due to the support plate 538 being positioned relatively low, during the early to mid-drying stages—the main stages of melting, leveling, and color change of the original wax on the bamboo 7—the bamboo 7 does not come into contact with the support plate 538. This prevents any contact between the bamboo 7 and the support plate 538 from affecting the melting and leveling of the wax, or causing color differences on the contact surface. Later in the drying process, the bamboo 7 will deform to some extent, and under its own weight and the influence of time, the middle area of ​​the suspended bamboo 7 will bend and sag. At this point, the leveling of the wax is complete, and the color change is basically fixed. The support plate 538 can prevent the bamboo 7 from undergoing excessive bending deformation. Of course, those skilled in the art will know that by increasing the distance between the first limiting rod 535 and the second limiting rod 536 and the support plate 538, the round bamboo 7 will not contact the support plate 538 after being initially suspended by the first limiting rod 535 and the second limiting rod 536, and the bending deformation of the round bamboo 7 will be limited. When the round bamboo 7 bends to the limited extent, the lowest point of the bend of the round bamboo 7 will contact the support plate 538. Preferably, the round bamboo 7 is allowed to bend by 3 to 5% of its length.

[0057] More preferably, the inner side of the crossbar 531 is provided with a movable groove 537, the length direction of the movable groove 537 is set along the length direction of the crossbar, and both ends of the support plate 538 are inserted into the movable grooves 537 of the crossbar 531 on both sides and can move in the movable grooves 537. By means of the cooperation between the movable groove 537 and the support plate 538, the setting position of the support plate 538 along the length direction of the crossbar 531 (i.e. the length direction of the round bamboo 7) can be manually changed, so that the supporting position of the support plate 537 on the round bamboo 7 is located at the bamboo node as much as possible, so as to further avoid the setting of the support plate 538 affecting the film formation of wax on the surface of the round bamboo 7 and the fixation of the material color.

[0058] Of course, those skilled in the art will know that when using a partition 53 with a support plate 538, the corresponding limiter should include two spaced apart to avoid the support plate 538.

[0059] During drying, round bamboo 7, including bamboo tubes, is selected, preserving the original waxy coating on the surface of the bamboo tubes. If round bamboo 7 with multiple sections is selected, the complete shape of the bamboo sections between adjacent tubes is preserved. The round bamboo 7 is placed horizontally and layer by layer on the material stacking rack 5, and then sent into the drying chamber 1. Preferably, after being sent in, the axial direction (length direction) of the round bamboo 7 is perpendicular to the output shaft of the fan 4. The drying chamber 1 is closed, and the heat source 2 and the humidity source 3 are adjusted through the control system of the drying chamber 1 to maintain the temperature of the drying medium at 60~100℃ and the relative humidity at 30~80%RH. The fan 4 is adjusted to maintain the flow rate of the drying medium at 2~8m / s. The above temperature, humidity, and flow rate of the drying medium are maintained until the moisture content of the round bamboo 7 drops to the required range, for example, 6~16%, and the round bamboo material is obtained.

[0060] By means of the above drying method, during the drying process of round bamboo, the following simultaneously occur: (1) the moisture content of the round bamboo decreases, so that the round bamboo has a moisture content within the range required for use, thus achieving the drying of the round bamboo; (2) the original wax on the outer surface of the bamboo tube melts to a certain extent and re-levels, and after drying, the original wax cools and solidifies, forming a protective coating attached to the outer surface of the bamboo tube, thus achieving a self-coating effect; (3) affected by temperature and humidity, the original wax and the bamboo green of the bamboo tube darken, changing the color of the round bamboo surface, thus achieving a self-coloring effect. Therefore, the difference between the round bamboo material obtained after drying and the round bamboo before drying is not only the decrease in moisture content, but also the fact that the original wax on the surface of the bamboo tube, which did not form a continuous film, becomes a continuous and uniform protective coating after melting, re-leveling, and cooling and solidifying, as well as the color change of the bamboo green and the color change of the original wax.

[0061] Specifically, current technology generally believes that bamboo green requires temperatures above 120℃ to undergo a reddish color change. However, at this temperature, the bamboo dries too quickly, easily leading to cracking and shrinkage of the bamboo walls, affecting the drying quality and resulting in relatively high energy consumption. The conventional drying temperature for bamboo is generally 40-50℃. At this temperature, the original wax on the bamboo precipitates out, and in some areas, the wax falls off, making the dried bamboo surface rough and unsightly. The remaining wax can also affect the adhesion of protective coatings. Therefore, current technology generally involves removing the original wax before drying or heat treatment to change the color of the bamboo, and finally impregnating the bamboo with paraffin wax or applying a paraffin wax coating to the surface for protection.

[0062] In contrast, the inventors in this case creatively discovered that, under the same drying conditions, the presence of the original waxy substance allows for a deeper color change in the bamboo's green color. In other words, compared to existing technologies that remove the original waxy substance from round bamboo while retaining only the green color, the drying method in this case only requires a relatively low drying temperature to achieve the same material color as the higher drying (heat treatment) temperatures of existing technologies. This discovery allows the drying method in this case to utilize a relatively low drying temperature, ensuring that the melting degree of the original waxy substance during the drying process only allows for re-leveling, rather than downward flow or dripping, and that a protective coating is formed on the bamboo tube after cooling and solidification. In particular, the protective coating formed after re-solidification, compared to the initial form of the original waxy substance, retains the protective effect of the original waxy substance while being smoother and having better gloss, making it a coating that combines protection and aesthetics. Therefore, by simply limiting the drying temperature to a range above the temperature at which the original wax on the surface of the bamboo tube can completely melt, the drying of the bamboo, the red coloring of the bamboo, and the protective coating on the surface of the bamboo can be achieved simultaneously.

[0063] Please see Figure 10 , Figure 10 The image shows the different color changes of round bamboo after undergoing the same drying process, with and without the original wax coating. As can be observed, the round bamboo with the original wax removed remains relatively light in color after drying, showing no coloring effect. The round bamboo with the original wax retained, after drying, darkens in color and undergoes coloring, resulting in a reddish, antique-looking material.

[0064] In summary, this method, through the aforementioned drying process, creates a protective coating on the bamboo's surface using the bamboo's natural waxes without introducing protective coatings or paints. Simultaneously, it allows the bamboo to undergo a reddish color change at lower temperatures, giving the bamboo a decorative effect. This method directly processes the bamboo, completing drying, protective coating, and decorative coating in one step. It boasts advantages such as simple processing, low cost, high bamboo utilization, and safety and environmental friendliness.

[0065] Example 1: In this example, the dried round bamboo is moso bamboo. No sorting or selection is performed based on the moisture content of the bamboo to be dried. There are five bamboo tubes along the length direction. Specifically, the nodes between the bamboo tubes are not opened to maintain relative separation between adjacent tubes. The initial lightness value of the outer surface of the round bamboo is 35.1~43.7, the red-green index is -3.6~-1.5, and the yellow-blue index is 8.7~13.5.

[0066] Drying conditions: drying temperature is 60℃, relative humidity is 30%RH, airflow velocity is 4m / s, and the final moisture content of round bamboo is 10~12%.

[0067] After drying, the obtained round bamboo material is referenced. Figure 9 As shown, the bamboo tube comprises, from the outside in, a bamboo green layer 71, a bamboo flesh layer 72, and a bamboo yellow layer 73. A protective coating 74 is present on the outer surface of the bamboo green layer 71. This protective coating 74 is a film-like coating formed by melting, leveling, and then cooling and solidifying the original waxy substance of the round bamboo. For ease of understanding, Figure 9 The bamboo tube was split in half, but in reality, the round bamboo material retains the complete shape of the bamboo tube and bamboo nodes.

[0068] Example 2: The difference between Example 2 and Example 1 is that the relative humidity for drying is 50%RH and the airflow speed is 3m / s.

[0069] Example 3: The difference between Example 3 and Example 1 is that the relative humidity for drying is 70%RH and the airflow speed is 5m / s.

[0070] Example 4: The difference between Example 4 and Example 1 is that the drying temperature is 70°C, the relative humidity is 65%RH, and the airflow speed is 6m / s.

[0071] Example 5: The difference between Example 5 and Example 1 is that the drying temperature is 75°C, the relative humidity is 30%RH, and the airflow speed is 5m / s.

[0072] Example 6: The difference between Example 6 and Example 5 is that the relative humidity for drying is 50%RH and the airflow speed is 4m / s.

[0073] Example 7: The difference between Example 7 and Example 5 is that the relative humidity for drying is 70%RH and the airflow speed is 3m / s.

[0074] Example 8: The difference between Example 8 and Example 1 is that the drying temperature is 80°C, the relative humidity is 65%RH, and the airflow speed is 3m / s.

[0075] Example 9: The difference between Example 9 and Example 8 is that the relative humidity for drying is 75%RH and the airflow speed is 4m / s.

[0076] Example 10: The difference between Example 10 and Example 1 is that the drying temperature is 85°C, the relative humidity is 65%RH, and the airflow speed is 5m / s.

[0077] Example 11: The difference between Example 11 and Example 1 is that the drying temperature is 90°C, the relative humidity is 30%RH, and the airflow speed is 4m / s.

[0078] Example 12: The difference between Example 12 and Example 11 is that the relative humidity for drying is 50%RH and the airflow speed is 4m / s.

[0079] Example 13: The difference between Example 13 and Example 11 is that the relative humidity for drying is 65%RH and the airflow speed is 5m / s.

[0080] Example 14: The difference between Example 14 and Example 11 is that the relative humidity for drying is 70%RH and the airflow speed is 4m / s.

[0081] Example 15: The difference between Example 15 and Example 11 is that the relative humidity for drying is 75%RH and the airflow speed is 2m / s.

[0082] Example 16: The difference between Example 10 and Example 1 is that the drying temperature is 100℃, the relative humidity is 70%RH, and the airflow speed is 4m / s.

[0083] Compare with Example 1: Fresh moso bamboo and round bamboo.

[0084] Comparative Example 2: Fresh moso bamboo after the original wax on the surface has been removed using chemical reagents.

[0085] Comparative Example 3: The difference between Comparative Example 3 and Comparative Example 2 is that the round bamboo after wax removal was dried to a moisture content of 10-12% under drying conditions of 60°C, 50%RH relative humidity, and 2m / s airflow.

[0086] Comparative Example 4: The difference between Comparative Example 4 and Comparative Example 3 is that the drying temperature is 75℃.

[0087] Comparative Example 5: The difference between Comparative Example 5 and Comparative Example 3 is that the drying temperature is 90℃.

[0088] Comparative Example 6: The difference between Comparative Example 6 and Comparative Example 3 is that a paraffin coating is applied to the surface of round bamboo to form a protective coating.

[0089] Comparative Example 7: The drying method described in the invention patent application with publication number CN109227839A entitled "A Method for Drying and Heat Treatment of Round Bamboo" was adopted, with a drying temperature of 180℃ and a final moisture content of 6-8% for the round bamboo.

[0090] Table 1 shows the performance parameters of the round bamboo in Examples 1-16 and Comparative Examples 1-7. Among them, the color of the material was characterized using the dial indicator method according to the L*a*b* colorimetric system of the International Commission on Illumination (CLE) 1976. The color indices L*, a*, and b* of the outer surface of the sample before and after drying were measured using a colorimeter (CR-20, Konica Minolta). Roughness was observed using a white light interferometer (ER-230, Atometrics, China) to observe the three-dimensional morphology of the round bamboo surface, and the roughness characterization value Sa (Sa is the arithmetic mean height) of the sample surface was measured according to ISO-25178. Pencil hardness was characterized using a pencil hardness tester (HK-QHQ, Huaguo Precision Technology Co., Ltd.) according to ASTM D3363-2005. The dried round bamboo was processed into 20mm wide samples and placed on the stage of the pencil hardness tester. A fixed pencil was pressed on the surface of the round bamboo to draw lines, and the pencil hardness was gradually increased until various defects defined by the standard appeared on the surface of the round bamboo. Peel test: Transparent tape was firmly attached to the surface of the round bamboo and then peeled off at a uniform speed. The morphology of the round bamboo surface was observed. In Table 1, the symbol "-" indicates that it cannot be detected. See the before and after photos for reference. Figure 11 As shown.

[0091] Table 1. Comparison of performance parameters of bamboo materials in Examples 1-16 and Comparative Examples 1-7

[0092]

[0093] As shown in Table 1:

[0094] (1) Under the same relative humidity conditions, the brightness gradually decreases as the drying temperature increases. This indicates that within the temperature range of 60~100℃, the higher the temperature, the darker the color of the material. Under the same drying temperature conditions, the relative humidity has no significant effect on the brightness of bamboo; only when the drying temperature is higher, the relative humidity is higher and the color of the material appears slightly darker.

[0095] (2) The red-green index changes from negative to positive, which makes the dried bamboo appear red. Under the same relative humidity conditions, the red-green index gradually increases with the increase of drying temperature. This indicates that within the temperature range of 60~100℃, the higher the temperature, the more red the bamboo appears. Under the same drying temperature conditions, changes in relative humidity have almost no effect on the red-green index of bamboo.

[0096] (3) The yellow-blue index does not change significantly and there is no obvious pattern of change. The bamboo material still appears yellow.

[0097] (4) The protective coating formed by melting, leveling, and curing the virgin wax in this technical solution has higher smoothness, hardness, and adhesion. In particular, when the temperature range is 80~90℃, the surface is smooth after drying, and the color is beautiful, uniform, and glossy. When the drying temperature reaches 100℃, although the protective coating is smooth, has high hardness, and good adhesion, and the bamboo material shows a beautiful red color, it will produce more serious shrinkage and internal cracks, which is not conducive to the processing of round bamboo products.

[0098] The above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will become apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the appended claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject disclosed herein in the preceding claims is not an abandonment of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed application subject matter.

Claims

1. A round bamboo material, comprising a bamboo tube and a protective coating covering the outer surface of the bamboo tube, characterized in that, The round bamboo material comprises multiple bamboo tubes, with adjacent bamboo tubes separated by bamboo nodes. The protective coating is the original waxy substance on the surface of the bamboo tubes, and the protective coating is applied to all parts of the surface of the bamboo tubes. The roughness value of the protective coating is 0.8~2.1μm; the moisture content of the bamboo material is 6~16%. The protective coating has a pencil hardness test value higher than 4H and can withstand at least 120 tape peel tests. The lightness value of the round bamboo material is 26.9~31.2, the red-green index is 4.9~5.9, and the yellow-blue index is 9.6~12.9; The round bamboo material is prepared by the following round bamboo drying method that enables self-coloring and self-coating: during drying, the temperature of the drying medium is 80~90℃, the humidity is 65~75%RH, and the flow rate is 3~5m / s.

2. The round bamboo material according to claim 1, characterized in that, The round bamboo material is moso bamboo, green bamboo, hemp bamboo, or small-leaf bamboo.

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