Preparation method of bamboo shaving multi-layer composite outdoor floor

Abstract

This invention relates to the field of engineered wood processing technology and discloses a method for preparing multi-layer composite outdoor flooring made of bamboo shavings. The method involves first treating bamboo shavings and poplar wood raw materials with an alkaline solution to produce bamboo shavings and poplar veneers; then treating the bamboo shavings and poplar veneers with cold plasma; finally, immersing the cold plasma-treated bamboo shavings and poplar veneers in phenolic resin containing nano-silica; after impregnation, assembling the veneers into a blank; and finally, hot-pressing the blank into multi-layer composite outdoor flooring made of bamboo shavings. This method uses bamboo shavings, poplar wood, nano-silica, and phenolic resin to prepare the outdoor flooring. The preparation method employs cold plasma technology with two atmospheres: oxygen / carbon dioxide and chlorine / argon, to treat the bamboo shavings and poplar wood. The treated bamboo shavings and poplar wood can form chemical bonds with nano-silica and phenolic resin, significantly improving the structural strength, water resistance, and corrosion resistance of the outdoor flooring.

Description

Technical Field

[0001] This invention relates to the field of engineered wood processing technology, and in particular to a method for preparing multi-layer composite outdoor flooring made of bamboo shavings. Background Technology

[0002] The raw materials for outdoor flooring include stone, wood, wood-plastic composites, and bamboo. Among these, bamboo has attracted much attention from those skilled in the art due to its wide availability, low cost, aesthetic appeal, and environmental friendliness. However, bamboo also suffers from poor durability, easy deformation, poor water resistance, and poor corrosion resistance. Therefore, existing technologies typically require modification treatments for bamboo raw materials.

[0003] There are various methods for modifying bamboo, among which plasma modification is a commonly used method. For example, CN116690742B discloses a method for modifying bamboo by producing aragonite-type nano-calcium carbonate. This technical solution uses air-atmosphere plasma to pretreat the bamboo, causing the bamboo surface to form more active functional groups such as hydroxyl and phenolic hydroxyl groups, thereby improving surface hydrophilicity, wettability, and adhesion. Another example is the paper "The Influence of Oxygen-Cold Plasma Treatment on the Surface Wetting of Bamboo," which discloses that treating moso bamboo with oxygen, nitrogen, and argon plasma improves the contact angle of phenolic resin on its surface. Yet another example is CN118107029B, which discloses a method for preparing glue-free bamboo-based fiberboard using a three-stage low-temperature plasma treatment: a carbon dioxide / oxygen stage, a argon / helium stage, and ammonia / nitrogen stage. The use of a mixed gas atmosphere increases the content of specific functional groups. The results of the above-mentioned existing technologies show that different atmospheres of plasma treatment can produce different technical effects on bamboo. However, the atmospheres used in the current technologies are mainly gases such as oxygen, nitrogen, carbon dioxide, argon and ammonia, and other atmospheres have not been studied. Therefore, developing other modified atmospheres is of great significance for expanding bamboo modification technology solutions. Summary of the Invention

[0004] This invention provides a method for preparing multi-layer composite outdoor flooring made of bamboo shavings. The method uses bamboo shavings, poplar wood, nano-silica, and phenolic resin as raw materials to prepare the board. The method employs a two-stage cold plasma treatment of bamboo shavings and poplar wood. The first stage uses an atmosphere of oxygen and carbon dioxide, while the second stage uses an atmosphere of chlorine and argon. Through the two-stage cold plasma treatment, the bamboo shavings and poplar wood form bonds with nano-silica and phenolic resin, significantly improving the strength, water resistance, and corrosion resistance of the outdoor flooring.

[0005] The specific technical solution of this invention is as follows: A method for preparing multi-layer composite outdoor flooring made of bamboo shavings includes the following steps: (1) Bamboo shavings and poplar wood raw materials are treated with alkali solution to produce bamboo shavings and poplar veneer; (2) Cold plasma treatment of bamboo shavings and poplar veneer. The cold plasma treatment includes a first-stage treatment and a second-stage treatment. The conditions for the first-stage treatment include: an atmosphere of oxygen and carbon dioxide. The conditions for the second-stage treatment include: an atmosphere of argon and chlorine. (3) The cold plasma treated bamboo shavings and poplar veneer are immersed in phenolic resin containing nano-silica to make core layer, sub-surface layer, surface layer and filling layer respectively. After impregnation, they are assembled into blanks and then hot-pressed into bamboo shaving multi-layer composite outdoor flooring.

[0006] Preferably, the alkaline solution is one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, and calcium carbonate.

[0007] As a preferred option, the conditions for the first-stage treatment also include: power of 300~500 W, time of 3~10 min, and carbon dioxide content of 20~50%.

[0008] As a preferred option, the conditions for the two-stage treatment also include: power of 200~300 W, time of 2~4 min, and chlorine content of 20~30%.

[0009] Preferably, the solid content of hydrophobic nano-silica in the phenolic resin is 30-50%.

[0010] Preferably, the molecular weight of the phenolic resin is 800-1000.

[0011] Preferably, the hot pressing pressure is 3~3.5 MPa.

[0012] Preferably, the hot pressing temperature is 150~160℃.

[0013] Preferably, the hot pressing time is 0.9~1 mm / min.

[0014] As a preferred option, embossed steel sheet is used for embossing.

[0015] Preferably, the embryo assembly sequence is: surface layer, filling layer, subsurface layer, filling layer, core layer, filling layer, subsurface layer, filling layer, and surface layer.

[0016] This invention provides a method for preparing multi-layer composite outdoor flooring made from bamboo shavings. The raw materials used in this method are bamboo shavings, poplar wood, nano-silica, and phenolic resin. Before use, the bamboo shavings and poplar wood are treated with an alkaline solution. The treated bamboo shavings and poplar wood are then treated with cold plasma. After cold plasma treatment, they are immersed in phenolic resin containing nano-silica, and finally, the flooring is cured by hot pressing to produce the outdoor flooring. This flooring exhibits significantly enhanced corrosion resistance, water resistance, and structural strength.

[0017] This invention uses phenolic resin with nano-silica as an adhesive for bamboo shavings and poplar wood. During research, it was found that when nano-silica and phenolic resin are combined with unmodified bamboo shavings and poplar wood, hydrogen bonding is the dominant process. This results in low interlayer bonding strength in the composite material, and the bamboo shavings and poplar wood are prone to mold and deformation. Therefore, this invention employs alkaline treatment and cold plasma treatment to modify the bamboo shavings and poplar wood. Alkaline treatment disrupts the lignin structure, providing a carbon source for subsequent plasma modification and dissolving sugars, thus improving the material's anti-corrosion properties. Cold plasma can form functional groups such as hydroxyl and phenolic groups on the material surface, improving adhesion. Further research on cold plasma treatment of wood revealed that existing technologies using atmospheres such as air, oxygen, carbon dioxide, ammonia, nitrogen, argon, carbon dioxide / oxygen, and ammonia / nitrogen to treat bamboo produce different effects due to the different functional groups acquired on the material surface. Therefore, this invention optimizes the cold plasma atmosphere based on this principle.

[0018] This invention addresses the use of phenolic resin and nano-silica as adhesives for bamboo shavings and poplar wood. The final approach involves cold plasma treatment of both materials in two atmospheres: oxygen and carbon dioxide, and chlorine and argon. First, the oxygen and carbon dioxide atmosphere generates more carboxyl groups on the material surface. These carboxyl groups can form silicon-oxygen-carbon bonds with silica, chemically bonding the silica to the material and significantly enhancing the bonding ability. Silica also strengthens the mechanical properties of the bamboo shavings and poplar wood. Second, the chlorine and argon atmospheres, with their strong etching properties, roughen the material surface, creating a mechanical interlocking effect after lamination, further improving the bonding strength. Furthermore, chlorine can occupy some of the carboxyl groups, forming more reactive carbon-chlorine bonds. These carbon-chlorine bonds can chemically bond with the hydroxyl groups of the phenolic resin. Through these two cold plasma treatments in different atmospheres, both bamboo shavings and poplar wood can form chemical bonds with nano-silica and phenolic resin, significantly enhancing the structural strength and corrosion resistance of the composite board. In addition, nano-silica can improve the hydrophobicity and wear resistance of the board, significantly increasing the hydrophobicity and anti-slip properties of the composite board.

[0019] Compared with the prior art, this application has the following technical effects: (1) This invention uses bamboo shavings, poplar wood, nano silica and phenolic resin to prepare outdoor flooring. In the preparation method, cold plasma technology with two atmospheres of oxygen / carbon dioxide and chlorine / argon is used to treat bamboo shavings and poplar wood respectively. The treated bamboo shavings and poplar wood can form chemical bonds with nano silica and phenolic resin, which significantly improves the structural strength of outdoor flooring and significantly improves the water resistance and corrosion resistance of outdoor flooring. (2) The composite board adopts a multi-layer symmetrical structure during the assembly process, which can improve the stability and mechanical properties of the board. (3) Bamboo shavings and poplar wood can have their lignin structure destroyed after being treated with alkaline solution, providing a carbon source for subsequent oxygen / carbon dioxide cold plasma treatment, generating more carboxyl groups, and also dissolving initial sugars, thus improving their anti-mildew and anti-corrosion properties. Detailed Implementation

[0020] The present invention will be further described below with reference to embodiments.

[0021] To better understand the content of this invention, further explanation is provided below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of this invention.

[0022] Example 1: A method for preparing multi-layer composite outdoor flooring made of bamboo shavings includes the following steps: (1) Raw material preparation: Select bamboo materials without bamboo nodes, bamboo green and bamboo yellow, flatten them and then assemble them. Then, use disc shaving process to prepare bamboo shavings. The specifications of bamboo shavings are: length 200 mm to 300 mm, thickness 0.8 mm to 1.2 mm, width 13 mm to 25 mm. Select poplar veneer with a thickness of 1 mm. (2) Soak bamboo shavings and poplar veneer in an alkaline solution (calcium hydroxide with a concentration of 1 mol / L) for 3 h, then soak them in water for 24 h. After soaking, remove and dry them until the moisture content is below 5% for later use. (3) Bamboo shavings and poplar wood were placed in the cold plasma reaction chamber for the first stage of treatment. The vacuum was evacuated to 2 Pa to 4 Pa, the air was discharged, and a mixture of carbon dioxide and oxygen was introduced. The carbon dioxide content was 35%. The vacuum degree of the reaction chamber was adjusted to 45 Pa. The power of the radio frequency power supply was set to 250 W. The treatment lasted for 4 min. After the first stage of treatment, the mixed gas valve was closed, the residual gas was discharged, and the chamber was kept in a vacuum state. Then, a mixture of chlorine and argon was introduced for the second stage of treatment. The chlorine content was 25%. The vacuum degree of the chamber was adjusted to 50 Pa, the power supply was set to 250 W, and the treatment lasted for 3 min. After the treatment was completed, the mixed gas valve was closed, the vacuum was evacuated, and the residual gas was discharged for later use. (4) The treated bamboo shavings and poplar wood are immersed in phenolic resin containing nano-silica (molecular weight of 800 to 1000). The bamboo shavings are vacuum impregnated in phenolic resin with a nano-silica solid content of 50% for 10 min to form the core layer. The bamboo shavings are vacuum impregnated in phenolic resin with a nano-silica solid content of 30% for 10 min to form the sub-surface layer. The bamboo shavings are vacuum impregnated in phenolic resin with a hydrophobic nano-silica solid content of 35% for 10 min to form the surface layer. The poplar wood is vacuum impregnated in phenolic resin with a nano-silica solid content of 30% for 10 min to form the filling layer. (5) The blanks are assembled in the order of surface layer, filling layer, sub-surface layer, filling layer, core layer, filling layer, sub-surface layer, filling layer and surface layer to form a blank. The blank is sent into a hot press for hot pressing and curing. The hot pressing temperature is 150 ℃, the hot pressing pressure is 3MPa, and the hot pressing time is 1 min / mm according to the plate thickness. During the hot pressing process, an embossed steel plate is placed on the upper surface layer. After hot pressing and curing, bamboo shavings multi-layer composite outdoor flooring is made.

[0023] Example 2: (1) Raw material preparation: Select bamboo materials without bamboo nodes, bamboo green and bamboo yellow, flatten them and then assemble them. Then, use disc shaving process to prepare bamboo shavings. The specifications of bamboo shavings are: length 200 mm to 300 mm, thickness 0.8 mm to 1.2 mm, width 13 mm to 25 mm. Select poplar veneer with a thickness of 1 mm. (2) Soak bamboo shavings and poplar veneer in an alkaline solution (calcium hydroxide with a concentration of 1 mol / L) for 3 h, then soak them in water for 24 h. After soaking, remove and dry them until the moisture content is below 5% for later use. (3) Bamboo shavings and poplar wood were placed in the cold plasma reaction chamber for the first stage of treatment. The vacuum was evacuated to 2 Pa to 4 Pa, the air was discharged, and a mixture of carbon dioxide and oxygen was introduced. The carbon dioxide content was 20%. The vacuum degree of the reaction chamber was adjusted to 45 Pa. The power of the radio frequency power supply was set to 200 W. The treatment lasted for 5 min. After the first stage of treatment, the mixed gas valve was closed, the residual gas was discharged, and the chamber was kept in a vacuum state. Then, a mixture of chlorine and argon was introduced for the second stage of treatment. The chlorine content was 20%. The vacuum degree of the chamber was adjusted to 50 Pa, the power supply was set to 200 W, and the treatment lasted for 4 min. After the treatment was completed, the mixed gas valve was closed, the vacuum was evacuated, and the residual gas was discharged for later use. (4) The treated bamboo shavings and poplar wood are immersed in phenolic resin (molecular weight of 800 to 1000) containing hydrophobic nano silica. The bamboo shavings are vacuum impregnated in phenolic resin with a nano silica solid content of 50% for 10 min to form the core layer. The bamboo shavings are vacuum impregnated in phenolic resin with a nano silica solid content of 30% for 10 min to form the sub-surface layer. The bamboo shavings are vacuum impregnated in phenolic resin with a hydrophobic nano silica solid content of 35% for 10 min to form the surface layer. The poplar wood is vacuum impregnated in phenolic resin with a nano silica solid content of 30% for 10 min to form the filling layer. (5) The blanks are assembled in the order of surface layer, filling layer, sub-surface layer, filling layer, core layer, filling layer, sub-surface layer, filling layer and surface layer to form a blank. The blank is sent into a hot press for hot pressing and curing. The hot pressing temperature is 150 ℃, the hot pressing pressure is 3MPa, and the hot pressing time is 1 min / mm according to the plate thickness. During the hot pressing process, an embossed steel plate is placed on the upper surface layer. After hot pressing and curing, bamboo shavings multi-layer composite outdoor flooring is made.

[0024] Example 3: (1) Raw material preparation: Select bamboo materials without bamboo nodes, bamboo green and bamboo yellow, flatten them and then assemble them. Then, use disc shaving process to prepare bamboo shavings. The specifications of bamboo shavings are: length 200 mm to 300 mm, thickness 0.8 mm to 1.2 mm, width 13 mm to 25 mm. Select poplar veneer with a thickness of 1 mm. (2) Soak bamboo shavings and poplar veneer in an alkaline solution (calcium hydroxide with a concentration of 1 mol / L) for 3 h, then soak them in water for 24 h. After soaking, remove and dry them until the moisture content is below 5% for later use. (3) Bamboo shavings and poplar wood were placed in the cold plasma reaction chamber for the first stage of treatment. The vacuum was evacuated to 2 Pa to 4 Pa, the air was discharged, and a mixture of carbon dioxide and oxygen was introduced. The carbon dioxide content was 50%. The vacuum degree of the reaction chamber was adjusted to 45 Pa. The power of the radio frequency power supply was set to 300 W. The treatment lasted for 3 min. After the first stage of treatment, the mixed gas valve was closed, the residual gas was discharged, and the chamber was kept in a vacuum state. Then, a mixture of chlorine and argon was introduced for the second stage of treatment. The chlorine content was 30%. The vacuum degree of the chamber was adjusted to 50 Pa, the power supply was set to 300 W, and the treatment lasted for 2 min. After the treatment was completed, the mixed gas valve was closed, the vacuum was evacuated, and the residual gas was discharged for later use. (4) The treated bamboo shavings and poplar wood are immersed in phenolic resin containing nano-silica (molecular weight of 800 to 1000). The bamboo shavings are vacuum impregnated in phenolic resin with a nano-silica solid content of 50% for 10 min to form the core layer. The bamboo shavings are vacuum impregnated in phenolic resin with a nano-silica solid content of 30% for 10 min to form the sub-surface layer. The bamboo shavings are vacuum impregnated in phenolic resin with a hydrophobic nano-silica solid content of 35% for 10 min to form the surface layer. The poplar wood is vacuum impregnated in phenolic resin with a nano-silica solid content of 30% for 10 min to form the filling layer. (5) The blanks are assembled in the order of surface layer, filling layer, sub-surface layer, filling layer, core layer, filling layer, sub-surface layer, filling layer and surface layer to form a blank. The blank is sent into a hot press for hot pressing and curing. The hot pressing temperature is 150 ℃, the hot pressing pressure is 3MPa, and the hot pressing time is 1 min / mm according to the plate thickness. During the hot pressing process, an embossed steel plate is placed on the upper surface layer. After hot pressing and curing, bamboo shavings multi-layer composite outdoor flooring is made.

[0025] Example 4: A method for preparing multi-layer composite outdoor flooring made of bamboo shavings includes the following steps: (1) Raw material preparation: Select bamboo materials without bamboo nodes, bamboo green and bamboo yellow, flatten them and then assemble them. Then, use disc shaving process to prepare bamboo shavings. The specifications of bamboo shavings are: length 200 mm to 300 mm, thickness 0.8 mm to 1.2 mm, width 13 mm to 25 mm. Select poplar veneer with a thickness of 1 mm. (2) Soak bamboo shavings and poplar veneer in an alkaline solution (calcium hydroxide with a concentration of 1 mol / L) for 3 h, then soak them in water for 24 h. After soaking, remove and dry them until the moisture content is below 5% for later use. (3) Bamboo shavings and poplar wood were placed in the cold plasma reaction chamber for the first stage of treatment. The vacuum was evacuated to 2 Pa to 4 Pa, the air was discharged, and a mixture of carbon dioxide and oxygen was introduced. The carbon dioxide content was 35%. The vacuum degree of the reaction chamber was adjusted to 45 Pa. The power of the radio frequency power supply was set to 250 W. The treatment lasted for 4 min. After the first stage of treatment, the mixed gas valve was closed, the residual gas was discharged, and the chamber was kept in a vacuum state. Then, a mixture of chlorine and argon was introduced for the second stage of treatment. The chlorine content was 25%. The vacuum degree of the chamber was adjusted to 50 Pa, the power supply was set to 250 W, and the treatment lasted for 3 min. After the treatment was completed, the mixed gas valve was closed, the vacuum was evacuated, and the residual gas was discharged for later use. (4) The treated bamboo shavings and poplar wood are immersed in phenolic resin containing nano-silica (molecular weight of 800 to 1000). The bamboo shavings are vacuum impregnated in phenolic resin with a nano-silica solid content of 50% for 10 min to form the core layer. The bamboo shavings are vacuum impregnated in phenolic resin with a nano-silica solid content of 30% for 10 min to form the sub-surface layer. The bamboo shavings are vacuum impregnated in phenolic resin with a hydrophobic nano-silica solid content of 30% for 10 min to form the surface layer. The poplar wood is vacuum impregnated in phenolic resin with a nano-silica solid content of 30% for 10 min to form the filling layer. (5) The blanks are assembled in the order of surface layer, filling layer, sub-surface layer, filling layer, core layer, filling layer, sub-surface layer, filling layer and surface layer to form a blank. The blank is sent into a hot press for hot pressing and curing. The hot pressing temperature is 150 ℃, the hot pressing pressure is 3MPa, and the hot pressing time is 1 min / mm according to the plate thickness. During the hot pressing process, an embossed steel plate is placed on the upper surface layer. After hot pressing and curing, bamboo shavings multi-layer composite outdoor flooring is made.

[0026] Example 5: A method for preparing multi-layer composite outdoor flooring made of bamboo shavings includes the following steps: (1) Raw material preparation: Select bamboo materials without bamboo nodes, bamboo green and bamboo yellow, flatten them and then assemble them. Then, use disc shaving process to prepare bamboo shavings. The specifications of bamboo shavings are: length 200 mm to 300 mm, thickness 0.8 mm to 1.2 mm, width 13 mm to 25 mm. Select poplar veneer with a thickness of 1 mm. (2) Soak bamboo shavings and poplar veneer in an alkaline solution (calcium hydroxide with a concentration of 1 mol / L) for 3 h, then soak them in water for 24 h. After soaking, remove and dry them until the moisture content is below 5% for later use. (3) Bamboo shavings and poplar wood were placed in the cold plasma reaction chamber for the first stage of treatment. The vacuum was evacuated to 2 Pa to 4 Pa, the air was discharged, and a mixture of carbon dioxide and oxygen was introduced. The carbon dioxide content was 35%. The vacuum degree of the reaction chamber was adjusted to 45 Pa. The power of the radio frequency power supply was set to 250 W. The treatment lasted for 4 min. After the first stage of treatment, the mixed gas valve was closed, the residual gas was discharged, and the chamber was kept in a vacuum state. Then, a mixture of chlorine and argon was introduced for the second stage of treatment. The chlorine content was 25%. The vacuum degree of the chamber was adjusted to 50 Pa, the power supply was set to 250 W, and the treatment lasted for 3 min. After the treatment was completed, the mixed gas valve was closed, the vacuum was evacuated, and the residual gas was discharged for later use. (4) The treated bamboo shavings and poplar wood are immersed in phenolic resin containing nano-silica (molecular weight of 800 to 1000). The bamboo shavings are vacuum impregnated in phenolic resin with a nano-silica solid content of 50% for 10 min to form the core layer. The bamboo shavings are vacuum impregnated in phenolic resin with a nano-silica solid content of 30% for 10 min to form the sub-surface layer. The bamboo shavings are vacuum impregnated in phenolic resin with a hydrophobic nano-silica solid content of 35% for 10 min to form the surface layer. The poplar wood is vacuum impregnated in phenolic resin with a nano-silica solid content of 30% for 10 min to form the filling layer. (5) The blanks are assembled in the order of surface layer, filling layer, sub-surface layer, filling layer, core layer, filling layer, sub-surface layer, filling layer and surface layer to form a blank. The blank is sent into a hot press for hot pressing and curing. The hot pressing temperature is 150 ℃, the hot pressing pressure is 3.5MPa, and the hot pressing time is 0.9 min / mm according to the plate thickness. During the hot pressing process, an embossed steel plate is placed on the upper surface layer. After hot pressing and curing, bamboo shavings multi-layer composite outdoor flooring is made.

[0027] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the plasma atmosphere is air, while all other conditions are the same as in Example 1.

[0028] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the plasma atmosphere consists only of oxygen and carbon dioxide, while all other conditions are the same as in Example 1.

[0029] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the plasma atmosphere is only chlorine and argon, while all other conditions are the same as in Example 1.

[0030] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the plasma atmosphere is only carbon dioxide, while all other conditions are the same as in Example 1.

[0031] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that the plasma atmosphere is only oxygen, while all other conditions are the same as in Example 1.

[0032] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that the plasma atmosphere is only chlorine gas, while all other conditions are the same as in Example 1.

[0033] Comparative Example 7: The difference between Comparative Example 7 and Example 1 is that the carbon dioxide content is too low, with a carbon dioxide content of 15%, while the other conditions are the same as in Example 1.

[0034] Comparative Example 8: The difference between Comparative Example 8 and Example 1 is that the chlorine content is too high and the carbon dioxide content is 40%, while the other conditions are the same as in Example 1.

[0035] Comparative Example 9: The difference between Comparative Example 9 and Example 1 is that the plasma treatment time was too long, while the other conditions were the same as in Example 1.

[0036] Comparative Example 10: The difference between Comparative Example 10 and Example 1 is that no alkali treatment was performed, while all other conditions were the same as in Example 1.

[0037] Comparative Example 11: Comparative Example 11 is a traditional homogeneous single-layer veneer structure. All bamboo shavings were impregnated in nano-silica phenolic resin with a solid content of 35% and then randomly laid into a board blank. All other conditions were the same as in Example 1.

[0038] Detection Example 1: The performance of the bamboo shavings multilayer composite outdoor flooring prepared in Examples 1 to 5 and Comparative Examples 1 to 11 was tested. The test items included: static bending strength, modulus of elasticity, internal bond strength, 24-hour water absorption thickness swelling rate, surface abrasion resistance, surface bond strength, and warpage. The test methods for static bending strength, modulus of elasticity, internal bond strength, 24-hour water absorption thickness swelling rate, surface bond strength, and warpage were in accordance with "GB / T 17657 Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". The test method for surface abrasion resistance was in accordance with "GB / T 18102 Impregnated Paper Laminate Wood Flooring". The test results are shown in Table 1. Table 1 Test results of Examples 1 to 5 and Comparative Examples 1 to 11 As shown in Table 1, the static bending strength of the bamboo shavings multi-layer composite outdoor flooring prepared by this invention is 68.2~69.8 MPa, the elastic modulus is 7810~7950 MPa, the internal bonding force is 1.78~1.82 MPa, the thickness expansion rate after 24 hours of water absorption is 3.8~3.9, the surface abrasion resistance is 1180~12500 revolutions, the surface bonding force is 2.12~2.20 MPa, and the warpage is 1.1~1.2 mm / m. From the above results, it can be seen that the bamboo shavings multi-layer composite outdoor flooring prepared by this invention is not easily deformed and has excellent structural strength, water resistance and abrasion resistance.

[0039] The effects of different plasma atmospheres were investigated in Comparative Examples 1, 2, 3, 4, 5, and 6. The results showed that flooring made using only air, oxygen, chlorine, oxygen / carbon dioxide, and chlorine / argon atmospheres was significantly inferior to the present invention in terms of structural strength, water resistance, and abrasion resistance. Further analysis compared the oxygen / carbon dioxide atmosphere and the chlorine / argon atmosphere alone. The oxygen / carbon dioxide atmosphere showed significantly higher abrasion resistance than the chlorine and argon atmospheres alone. This indicates that oxygen and carbon dioxide can improve the bonding ability between silica and the material, thereby improving the abrasion resistance of the flooring. Furthermore, the static bending strength, elastic modulus, internal bonding force, and 24-hour water absorption thickness expansion rate of the chlorine / argon atmosphere were significantly lower than those of the air and oxygen / carbon dioxide atmospheres alone. This indicates that treating the material with chlorine / argon atmosphere alone cannot effectively improve the bonding strength between the material and the adhesive. Analysis revealed that using chlorine / argon atmosphere alone only causes surface etching and does not introduce reactive functional groups into the material.

[0040] Comparative Examples 5 and 6 showed problems of over-oxidation and over-etching when only oxygen and chlorine were used, respectively, resulting in excessive damage to the wood fibers and a decrease in the overall performance of the flooring. Comparative Examples 7, 8, and 9 investigated the oxygen content, chlorine content, and treatment time. The results showed that excessive oxygen content caused over-oxidation, excessive chlorine content caused over-etching, and excessive treatment time caused over-oxidation and over-etching. All of these problems led to a decrease in the overall performance of the flooring.

[0041] In Comparative Example 10, no alkaline treatment was used. The results showed that the bonding strength of the flooring made using the untreated solution was reduced. This result indicates that alkaline treatment can enhance the bonding strength of the flooring. Further analysis revealed that the lignin structure in the material was destroyed after alkaline treatment, exposing the internal cellulose lignin, which provides more carbon source during subsequent plasma treatment, thereby forming more effective functional groups on the material surface.

[0042] Comparative Example 11 is a traditional light-spotted homogeneous structure. The board made with this structure has significantly lower overall performance compared with Example 1. This result indicates that the multi-layer composite floor made by the present invention has superior structural strength.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing multi-layer composite outdoor flooring made of bamboo shavings, characterized in that, Includes the following steps: (1) Bamboo shavings and poplar wood raw materials are treated with alkali solution to produce bamboo shavings and poplar wood veneer; (2) Cold plasma treatment of bamboo shavings and poplar veneer, including a first-stage treatment and a second-stage treatment; The conditions for the first-stage treatment include an atmosphere of oxygen and carbon dioxide; the conditions for the second-stage treatment include an atmosphere of argon and chlorine. (3) The cold plasma treated bamboo shavings and poplar veneer are immersed in phenolic resin containing nano-silica to make core layer, sub-surface layer, surface layer and filling layer respectively. After impregnation, they are assembled into blanks and then hot-pressed into bamboo shaving multi-layer composite outdoor flooring.

2. The preparation method according to claim 1, characterized in that, The alkaline solution is one or more of sodium hydroxide, calcium hydroxide, potassium hydroxide, and calcium carbonate.

3. The preparation method according to claim 1, characterized in that, The conditions for cold plasma treatment also include: an electrode-to-plate spacing of 0.5-1.5 mm, a power of 1000-2000 W, and a plate movement speed of 10-20 m / min.

4. The preparation method according to claim 1, characterized in that, The solid content of hydrophobic nano-silica in phenolic resin is 30-50%.

5. The preparation method according to claim 1 or 4, characterized in that, The molecular weight of phenolic resin is 800~1000.

6. The preparation method according to claim 1, characterized in that, The hot pressing pressure is 3~3.5 MPa, the hot pressing temperature is 150~200℃, and the hot pressing time is 0.9~1 mm / min.

7. The preparation method according to claim 1, characterized in that, The conditions for the first stage of processing also include: power of 300~500w and time of 3~10 min; the conditions for the second stage of processing also include: power of 200~300w and time of 2~4 min.

8. The preparation method according to claim 1, characterized in that, Chlorine accounts for 20-30%.

9. The preparation method according to claim 1, characterized in that, Carbon dioxide accounts for 20-50%.

10. The preparation method according to claim 1, characterized in that, The embryo assembly sequence is: surface layer, filling layer, subsurface layer, filling layer, core layer, filling layer, subsurface layer, filling layer, and surface layer.

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