Highly flame-retardant and highly waterproof bamboo body self-gluing reconstituted wood and manufacturing method thereof

Abstract

The application discloses a kind of high flame-retardant high waterproof bamboo body self-gluing reconstituted wood and its manufacturing method, manufacturing method includes the following steps: S1, after drying, bamboo shaving is treated with benzene alcohol extraction, after washing, the extracted shaving unit is obtained;S2, the extracted shaving unit is pretreated with lye, and the pretreated shaving unit is obtained;S3, after the pretreated shaving unit is dry balanced treatment, it is immersed in sodium silicate aqueous solution and treated, and the immersed shaving unit is obtained;S4, after the immersed shaving unit is dry balanced treatment, it is molded, and the temperature is 150~200 ℃, and the pressure is 10~45MPa Condition is molded into shape treatment, and after cooling, the bamboo body self-gluing reconstituted wood is obtained by demolding.The bamboo body self-gluing reconstituted wood prepared by the application does not need to add adhesive in the manufacturing process, and can be formed by one-time molding, the product has the advantages of high strength, weather resistance, flame retardant and formaldehyde-free and phenol-free release, and the production and manufacturing can realize the full biomass utilization of bamboo resources.

Description

Technical Field

[0001] This invention relates to the field of reconstituted bamboo manufacturing technology, and in particular to a self-adhesive reconstituted bamboo material and its manufacturing method. Background Technology

[0002] Against the backdrop of global sustainable development, bamboo, as the world's "second largest forest" resource, has been listed as a major focus for wood, plastic, and steel substitution due to its outstanding advantages such as short growth cycle and high strength-to-weight ratio. With continuous breakthroughs in modern bamboo processing and reconstituted technologies, bamboo has been processed into various bamboo composite reconstituted materials, such as bamboo plywood, reconstituted bamboo, bamboo engineered wood, and bamboo laminated lumber. These technologies have completely overcome the structural defects of bamboo itself, such as thin walls, hollow structure, and large taper, enabling controllable design and manufacturing of structure and specifications.

[0003] However, existing industrialized bamboo composite reconstituted technologies mostly use aldehyde and phenolic resins as adhesives, which can cause indoor environmental pollution due to the release of aldehydes and phenols, thus limiting their applicability. To overcome these technical bottlenecks, a few scholars have focused on high-temperature molding and bulk adhesive forming technology for biomass materials in recent years. Although they have achieved high-strength, environmentally friendly, and glue-free molding of reconstituted bamboo, the products still suffer from poor weather resistance and insufficient functionality, especially in terms of fire resistance and liquid resistance, which have not been significantly improved.

[0004] For example, there is a current technology for preparing a non-adhesive bamboo powder dense material. Bamboo chips are hydrothermally treated and then pulverized into bamboo powder. The bamboo powder is preheated, laid out, and then molded to obtain the non-adhesive bamboo powder dense material. This technology reduces the physical and mechanical properties of the powder through hydrothermal treatment, thus reducing molding rebound and increasing the density of the material. To a certain extent, it achieves a green and environmentally friendly dense material without the use of adhesives. However, the applicant has found that in this technology, hydrothermal treatment only softens the powder and reduces product rebound deformation; it does not initiate the bonding free radicals required for the subsequent self-adhesion process. The final product's static bending strength is below 30 MPa, and its 24-hour water absorption thickness expansion rate is above 15%, which to some extent limits the product's application range.

[0005] On the other hand, existing industrially promoted bamboo composite reconstituted products suffer from poor bonding performance due to the influence of bamboo's green and yellow components. The preparation process requires removing these components, resulting in a bamboo raw material utilization rate of less than 60% (and sometimes even less than 30%). Therefore, ensuring the efficient utilization of bamboo resources while producing green, environmentally friendly, high-strength, and functional bamboo reconstituted materials to meet the high-strength load-bearing requirements of indoor and outdoor construction, transportation, and harsh environments is of practical significance for increasing the added value of bamboo products and promoting the high-quality development of my country's bamboo industry. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a high flame retardant and high waterproof bamboo self-adhesive reconstituted material that can be formed in one molding process without any adhesive additives, and has high strength, good water resistance and no formaldehyde or phenol release, as well as the manufacturing method thereof.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for manufacturing a highly flame-retardant and highly waterproof bamboo self-adhesive composite material includes the following steps:

[0009] S1, the dried bamboo shavings are subjected to benzene alcohol extraction treatment, washed, and the extracted shavings unit is obtained.

[0010] S2, the extracted wood shavings unit is pretreated with alkali solution to obtain pretreated wood shavings unit;

[0011] S3. After drying and balancing the pretreated wood shavings, place them in an aqueous sodium silicate solution for impregnation to obtain the impregnated wood shavings.

[0012] S4. After the impregnated wood shavings are dried and balanced, they are molded and molded under conditions of 150~200℃ and 10~45MPa. After cooling, they are demolded to obtain bamboo self-adhesive reconstituted material.

[0013] As a further improvement to the above technical solution:

[0014] In step S1, the dried bamboo shavings include the following preparation steps: bamboo raw materials are made into bamboo shavings and dried to an air-dry state to obtain dried bamboo shavings.

[0015] In step S1, the bamboo raw material is one or more of bamboo green, bamboo yellow, bamboo flesh, or bamboo processing residues.

[0016] Preferably, in step S1, the drying to an air-dry state is carried out using a single-channel rotary drum dryer, with superheated steam as the drying medium, a drying temperature of 100~110℃, a rotation speed of 30~50 r / min, and a drying time of 3~10 min.

[0017] Preferably, in step S1, the moisture content of the air-dried bamboo shavings is about 8% to 18%.

[0018] In step S1, the benzyl alcohol extraction treatment includes the following steps: mixing dried bamboo shavings with a benzyl alcohol mixture and then treating it under microwave radiation intensity of 80~100W for 30~60 minutes, followed by extraction treatment under water bath conditions for 1~2 hours. The purpose of the benzyl alcohol extraction treatment is to remove organic extracts from the bamboo to obtain purified shaving units, thereby reducing the impact of organic extracts on the subsequent self-adhesion effect of the bamboo. The purpose of microwave radiation is to shorten the benzyl alcohol extraction treatment time and improve the extraction efficiency.

[0019] In step S1, the material-to-liquid ratio of the dried bamboo shavings and benzene alcohol mixture is 1:20~50. Here, the material-to-liquid ratio refers to the ratio of the mass of the bamboo shavings to the volume of the benzene alcohol mixture.

[0020] Preferably, in step S1, the benzene-alcohol mixture is a mixture of benzene and alcohol, with a volume ratio of benzene to alcohol of 2:1.

[0021] Preferably, in step S1, the alcohol is ethanol.

[0022] Preferably, in step S1, after the extraction process, the bamboo shavings are rinsed and filtered with alcohol and deionized water in sequence.

[0023] In step S2, the alkaline pretreatment includes the following steps: placing the extracted wood shavings in a 5-20 wt% alkaline solution and performing chemical pretreatment at a temperature of 140-160℃ for 0.5-1 h to obtain the pretreated wood shavings.

[0024] Alkali pretreatment aims to selectively remove hemicellulose and some lignin from bamboo shavings, causing them to depolymerize into highly reactive free radical intermediates such as monosaccharides and aldehydes. Simultaneously, it effectively increases the micro-nano pore structure on the bamboo fiber cell walls, improving the permeability of the bamboo surface and providing more adsorption space for subsequent impregnation of the shavings. This also provides a structural basis for the later self-gluing and fusion of the micro-nano structures of the shavings. The alkali pretreatment time is controlled within the range of 0.5–1 hour, ensuring that only part of the lignin in the shavings degrades. This effectively promotes the degradation into smaller molecules, providing a material basis for subsequent repolymerization under the "wet-heat-force" action. Furthermore, the selective removal of substances from the bamboo cell walls ensures that some lignin does not completely degrade, maintaining its thermoplastic melting effect during the later molding process, thus effectively promoting the glue-free densification of the shavings.

[0025] In step S2, the material-to-liquid ratio of the wood shavings unit and the alkaline solution is 1:5~10. Here, the material-to-liquid ratio refers to the ratio of the mass of the wood shavings unit to the volume of the alkaline solution.

[0026] Preferably, in step S2, stirring is also performed during the chemical pretreatment process so that the wood shavings unit can fully contact the treatment liquid and obtain a better pretreatment effect.

[0027] In step S3, the impregnation process includes the following steps: placing the dried pretreated wood shavings unit in a 5-30 wt% sodium silicate aqueous solution, maintaining it at a temperature of 40-60℃ for 1-2 hours, and then removing it to obtain the impregnated wood shavings unit.

[0028] Impregnation is performed to load sufficient sodium silicate into the cell wall pores of the wood shavings. This allows the silicate anions to dehydrate and condense into larger colloidal particles during the subsequent high-temperature molding process, thus forming a larger and more stable three-dimensional network structure. This results in a uniform, stable, continuous, and dense protective film layer on the surface of the wood shavings, giving the bamboo reconstituted material excellent water resistance, fire resistance, and corrosion resistance.

[0029] Preferably, in step S3, the drying equilibrium treatment includes the following steps: drying the pretreated wood shavings unit at 80~100℃ using a vacuum drying method until the moisture content is less than 10%.

[0030] In step S4, the holding time for the molding process is 20-70 minutes; after demolding, curing and machining processes are also included.

[0031] Preferably, in step S4, the drying balancing process is carried out using a single-channel rotary drum dryer, with hot air as the drying medium, a drying temperature of 50~60℃, a rotation speed of 30~50 r / min, and a drying time of 20~60 min.

[0032] Preferably, in step S4, the target moisture content of the impregnated wood shavings unit after drying is in the range of 6% to 15%, so as to ensure the self-adhesion effect of the wood shavings body during the subsequent molding process.

[0033] Preferably, in step S4, the target moisture content is 6%~15%, which, under the synergistic effect of multiple couplings of "humidity-heat-mechanical" factors, better achieves chemical bonding and physical structural fusion of the bamboo material, effectively promoting the high-performance self-adhesive bonding and forming of the shavings unit. The shavings unit can also be formed and manufactured at any moisture content, but this will affect the performance of the final product.

[0034] Preferably, in step S4, the "molding" refers to feeding the wood shavings into the mold cavity in batches, ensuring that the wood shavings are evenly distributed within the cavity. Feeding in batches is necessary because the wood shavings are lightweight and have a high aspect ratio, making them prone to sticking and bridging, and resulting in poor flowability. Therefore, the feeding process should be careful and the force applied evenly to ensure that the wood shavings inserted into the mold cavity are uniform and flat.

[0035] Preferably, in step S4, the mold is a rigid metal mold made of alloy steel forging Cr12, and is used in combination with three components: a cavity, an upper die punch, and a lower die punch. The cavity has a quenching / tempering heat treatment hardness of HRC60~70 and an inner wall roughness of Ra0.4; the upper and lower die punches have a quenching / tempering heat treatment hardness of HRC55~60 and a surface roughness of Ra0.4; the preferred working surface clearance between the cavity and the upper and lower die punches is 0.05~0.08 μm to ensure that the volatiles generated during the molding process have an escape channel.

[0036] Preferably, in step S4, the mold should be lubricated before the shaving unit is filled with material, that is, a lubricating substance is coated on the inner wall of the cavity and the working surface of the die to facilitate the subsequent demolding process.

[0037] The lubricating substance is preferably liquid paraffin or zinc stearate.

[0038] Preferably, in step S4, the molding is a uniaxial, one-time bidirectional pressure closed molding plasticizing process, which can effectively realize the limited lateral flow of the wood shavings and promote the uniformity of the distribution of the wood shavings inside the slab.

[0039] Preferably, in step S4, the cooling is in-mold cooling, that is, the "cold removal" process is adopted. After the pressing process reaches the heat preservation and pressure holding time, the blank should be cooled to below 60°C by artificial or natural cooling before the pressure release and demolding processes can be carried out in sequence.

[0040] Preferably, in step S4, the demolding process should involve uniformly applying a vibration force of a certain frequency to the upper die pressing surface to ensure that the formed blank is completely ejected from the lower exit of the cavity.

[0041] As a general inventive concept, this invention also provides a highly flame-retardant and highly waterproof bamboo self-adhesive composite material, which is prepared by the aforementioned preparation method. The forming strength of the bamboo self-adhesive composite material exceeds 100 MPa, the thickness expansion rate of water absorption at room temperature in 24 hours is less than 1%, and the flame-retardant and smoke-suppressing performance reaches the flame-retardant level (B1 level).

[0042] Compared with the prior art, the advantages of the present invention are as follows:

[0043] (1) The method for manufacturing high flame retardant and high waterproof bamboo body glued reconstituted material of the present invention is based on the chemical and structural characteristics of the shaving unit body material. Under the condition of no addition, the shaving unit after being synergistically impregnated with alkaline solution and sodium silicate produces multiple coupling effects of chemical bonding, lignin thermoplastic fusion and physical structure inlay fusion under the synergistic coupling effect of temperature, pressure and moisture. At the same time, a uniform and dense three-dimensional network sodium silicate weather-resistant protective film can also be formed on the material surface, thereby realizing the high performance and functional self-gluing reconstituted molding of bamboo body unit.

[0044] (2) The method for manufacturing high flame retardant and high waterproof bamboo body glued reconstituted material of the present invention adopts the "alkali pretreatment + sodium silicate impregnation" synergistic treatment, which can significantly improve the water resistance, flame retardancy, smoke suppression and weather resistance of the material. On the one hand, the alkali treatment can selectively depolymerize bamboo hemicellulose and a small amount of lignin, and the generated highly active small molecules can undergo chemical condensation reaction based on the bamboo body material to achieve condensation crosslinking of the body material; on the other hand, the alkali selectively degrades hemicellulose and a portion of lignin in the wood shavings, promotes the formation of multi-level pore structure of cell wall, effectively increases the micro-nano porosity of bamboo cell wall, greatly increases the specific surface area and permeability of wood shavings, not only provides a smooth channel for subsequent impregnation treatment, but also optimizes the basic conditions required for multi-scale physical structure embedding and welding fusion in the subsequent body self-gluing synthesis process. On the other hand, alkaline pretreatment effectively increases the loading capacity of sodium silicate within the cell wall cavities of bamboo. Furthermore, the sodium silicate system utilizes the thermal effects of molding to form a robust and dense protective film with excellent sealing properties, effectively preventing liquid intrusion and significantly improving waterproofing and weather resistance, thereby extending product lifespan. When heated or exposed to fire, this protective layer promotes the formation of an inorganic silica slag thermal barrier on the product surface, effectively blocking some heat transfer. Moreover, the hydrolysis of sodium silicate forms polysilicic acid, and the resulting inorganic film also forms a barrier on the material surface, effectively preventing the convection of combustible gases and thus effectively inhibiting flame spread. Therefore, the product's flame retardant and smoke-suppressing effect can be improved by more than 80%. From the above, it can be seen that alkaline pretreatment and sodium silicate impregnation treatment have a significant enhancing and coupling effect on the self-adhesive functionalization of bamboo.

[0045] (3) Compared with existing high-performance bamboo reconstituted bamboo manufacturing technologies, this invention does not involve the addition of adhesives. While achieving functionalized self-adhesive forming of bamboo, it avoids the generation of volatile organic compounds such as aldehydes and free phenols from the source, thus solving the environmental safety risks associated with the release of toxic and harmful substances from bamboo reconstituted materials. This expands the application areas of bamboo reconstituted materials in indoor, vehicle, and harsh environments. Compared with traditional glue-free forming manufacturing technologies, the mechanical and weather resistance indicators of the products of this invention far surpass those of traditional glue-free bonded products, breaking through the technical bottleneck that traditional glue-free forming technologies cannot achieve high-performance manufacturing.

[0046] (4) The high flame-retardant and high waterproof bamboo composite material of the present invention has a forming strength exceeding 100MPa, a thickness expansion rate of less than 1% after 24 hours of room temperature water absorption, flame-retardant and smoke-suppressing performance reaching the flame-retardant level (B1 grade), and zero aldehyde and zero phenol release. It has the characteristics of high mechanical strength, water resistance, fire resistance and corrosion resistance, as well as the advantages of being green, environmentally friendly and pollution-free. It can meet the requirements of high-strength load-bearing applications in harsh environments, while effectively solving the problem of excessive release of toxic and harmful substances in bamboo-based engineered wood products. On the other hand, the present invention uses bamboo processing residues as raw materials, achieving the goal of high-strength and functional manufacturing of bamboo composite materials, while also realizing the full biomass utilization of bamboo resources (up to 100%), breaking through the technical bottleneck of difficulty in improving the utilization rate of bamboo resources. Attached Figure Description

[0047] Figure 1 The diagram shows the production process flow of bamboo self-adhesive reconstituted timber in Embodiments 1 and 2 of the present invention. Detailed Implementation

[0048] The present invention will be further described in detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.

[0049] Example 1:

[0050] A method for manufacturing a highly flame-retardant and highly waterproof bamboo self-adhesive composite material according to this embodiment includes the following steps:

[0051] (1) Bamboo raw material preparation: Take the processing residue generated during the loosening and crushing of fresh bamboo strips, remove the metal foreign objects, use a crusher to perform coarse grinding of the shavings, and then use a single-channel rotary drum dryer to dry for 10 minutes at a drying temperature of 105℃ and a rotation speed of 30 r / min to obtain dried shavings units.

[0052] (2) Microwave-assisted treatment: Weigh the target sample amount of the wood shaving unit, add benzene-ethanol mixture (benzene and ethanol volume ratio of 2:1) at a material-liquid ratio of 1:30, and treat the mixture for 60 min under microwave radiation intensity of 80W to obtain the microwave-treated wood shaving unit.

[0053] (3) Extraction of raw material benzene alcohol: The microwave-treated wood shavings and benzene alcohol mixture were extracted for 1.5 hours under water bath conditions, and the wood shavings were rinsed and filtered with alcohol and deionized water in turn to obtain the extracted wood shavings.

[0054] (4) Alkali pretreatment: The extracted wood shavings were placed in a 10wt% sodium hydroxide solution at a material-to-liquid ratio of 1:5 and treated at 160℃ for 0.5h before being taken out to obtain the wood shavings pretreated with alkali.

[0055] (5) Vacuum drying treatment: The wood shavings pretreated with alkali solution are placed in a vacuum dryer and dried at 100°C until the moisture content reaches 6%, and then taken out for use.

[0056] (6) Sodium silicate impregnation loading: The dried and pretreated wood shavings unit was placed in a 20wt% sodium silicate aqueous solution, and then completely immersed in the solution at a temperature of 60℃ for 2 hours before being removed to obtain the impregnated wood shavings unit.

[0057] (7) Drying and balancing treatment: Place the impregnated wood shavings unit in a single-channel rotary drum dryer until the target moisture content is adjusted to 6%, and then set aside for use.

[0058] (8) Raw material loading into the mold: Before loading, apply a thin layer of liquid paraffin to the inner wall of the cavity and the working surface of the die to form a very thin lubricating film. Otherwise, it will affect the surface quality and forming effect of the slab. Put the shavings into the mold cavity in batches and make the shavings evenly distributed in the cavity. During the powder loading process, be careful and apply even force to ensure that the loading effect is uniform and flat.

[0059] (9) One-time molding: The blank and mold together with the pad are sent into the hot press for uniaxial bidirectional molding. The molding process used is: molding temperature is 180℃, molding pressure is 20MPa, and holding time is 40min.

[0060] (10) Cooling and demolding of the blank: After the pressing process reaches the heat preservation and pressure preservation time, the blank should be cooled to below 60°C by natural cooling. Then, a certain frequency of vibration force is uniformly applied to the upper die pressing surface to ensure that the formed blank is completely removed from the lower outlet of the cavity to obtain the self-adhesive bamboo reconstituted material blank.

[0061] The actual density of the self-adhesive reconstituted bamboo material produced in this embodiment is 1.40 g / cm³. 3 It has a static bending strength of 105MPa, a bending elastic modulus of 9000MPa, a 24-hour water absorption thickness expansion rate of 0.92%, and flame retardant and smoke suppressant performance reaching the flame-retardant level (B1 grade). In addition, no adhesive substances are added during the manufacturing process, and the product achieves zero-formaldehyde and zero-phenol manufacturing of bamboo reconstituted materials, which can meet the high-strength load-bearing material requirements for indoor, vehicle and harsh conditions.

[0062] Example 2:

[0063] A method for manufacturing a highly flame-retardant and highly waterproof bamboo self-adhesive composite material according to this embodiment includes the following steps:

[0064] (1) Bamboo raw material preparation: Take the processing residue produced by the loosening and crushing of fresh bamboo strips, remove foreign objects with a metal detector, then coarsely grind it with a crusher, and then dry it for 8 minutes with a single-channel rotary drum dryer at a drying temperature of 100℃ and a rotation speed of 40 r / min to obtain dried wood shavings.

[0065] (2) Microwave-assisted treatment: Mix the wood shavings unit and benzene alcohol solution (benzene and ethanol volume ratio of 2:1) at a liquid-to-material ratio of 1:50, and treat the mixture for 30 minutes under microwave radiation intensity of 100W to obtain the wood shavings unit after microwave-assisted treatment.

[0066] (3) Extraction of raw material benzene alcohol: The microwave-treated wood shavings and benzene alcohol mixture were extracted for 1.5 hours under water bath conditions, and the wood shavings were rinsed and filtered with alcohol and deionized water in turn to obtain the extracted wood shavings.

[0067] (4) Alkali pretreatment: The extracted wood shavings were placed in a 20wt% sodium hydroxide solution at a material-to-liquid ratio of 1:8 and treated at 140℃ for 1 hour before being taken out to obtain the wood shavings pretreated with alkali.

[0068] (5) Vacuum drying treatment: After the alkali solution pretreatment, the wood shavings unit is placed in a vacuum dryer and dried at 80°C until the moisture content reaches 8%, and then taken out for use.

[0069] (6) Sodium silicate impregnation loading: The dried pretreated wood shavings were placed in a 30wt% sodium silicate aqueous solution, and then treated by the breathing impregnation method at a temperature of 50℃ for 1 hour before being taken out to obtain the impregnated wood shavings unit.

[0070] When the size of the wood shavings is large, the impregnation treatment adopts the breathing impregnation method, which uses negative pressure to compress the cell cavities and pores inside the bamboo. When the negative pressure is converted into positive pressure, the cell cavities and pores are fully opened, forming unobstructed channels to accelerate the penetration of the impregnating agent, which can significantly improve the drug loading and impregnation efficiency.

[0071] (7) Drying and balancing treatment: Place the impregnated wood shavings unit in a single-channel rotary drum dryer until the target moisture content is adjusted to about 12%, and then set aside for use.

[0072] (8) Raw material loading into the mold: Before loading, apply a thin layer of liquid paraffin to the inner wall of the cavity and the working surface of the die to form a very thin lubricating film. Otherwise, it will affect the surface quality and forming effect of the slab. Put the shavings into the mold cavity in batches and make the shavings evenly distributed in the cavity. During the powder loading process, be careful and apply even force to ensure that the loading effect is uniform and flat.

[0073] (9) One-time molding: The blank and mold together with the pad are sent into the hot press for uniaxial bidirectional molding. The molding process used is: molding temperature is 200℃, molding pressure is 40MPa, and holding time is 60min.

[0074] (10) Cooling and demolding of the blank: After the pressing process reaches the heat preservation and pressure preservation time, the blank should be cooled to below 60°C by natural cooling. Then, a certain frequency of vibration force is uniformly applied to the upper die pressing surface to ensure that the formed blank is completely removed from the lower outlet of the cavity to obtain the self-adhesive bamboo reconstituted material blank.

[0075] The actual density of the self-adhesive reconstituted bamboo material produced in this embodiment is 1.46 g / cm³. 3 It has a static bending strength of 120MPa, a bending elastic modulus of 10000MPa, a 24-hour water absorption thickness expansion rate of 0.66%, and flame retardant and smoke suppressant performance reaching the flame-retardant level (B1 grade). In addition, no adhesive substances are added during the manufacturing process, and the product achieves zero-formaldehyde and zero-phenol manufacturing of bamboo reconstituted materials, which can meet the high-strength load-bearing material requirements for indoor, vehicle and harsh conditions.

[0076] Comparative Example 1:

[0077] A method for manufacturing self-adhesive reconstituted bamboo in this comparative example is basically the same as the manufacturing method in Example 1, except that step (4) alkaline pretreatment is not performed. That is, after the shavings unit is subjected to benzene alcohol extraction treatment in step (3), it is subjected to drying treatment in step (5) and then subjected to sodium silicate impregnation and loading in step (6), and finally the thermoforming treatment is completed under high temperature and high pressure conditions.

[0078] Comparative Example 2:

[0079] A method for manufacturing self-adhesive reconstituted bamboo in this comparative example is basically the same as the manufacturing method in Example 1, except that step (6) sodium silicate impregnation treatment is not performed. That is, after the shavings unit is pretreated with alkali solution in step (4), vacuum dried in step (5), and dried and balanced in step (7), it is directly subjected to thermoforming treatment under high temperature and high pressure.

[0080] Comparative Example 3:

[0081] A method for manufacturing self-adhesive reconstituted bamboo in this comparative example is basically the same as the method in Example 2, except that the molding temperature is different; the molding temperature is 130°C. That is, after the shaving unit is prepared, thermoforming is completed at a molding temperature of 130°C.

[0082] Table 1. Performance test results of self-adhesive reconstituted bamboo prepared in each embodiment and comparative example.

[0083]

[0084] As shown in Table 1, in Comparative Example 1, without the alkaline pretreatment step, the wood shavings were directly dried and balanced before being filled and thermoformed. Consequently, the polysaccharides in the wood shavings could not be depolymerized into small molecules with adhesive properties, such as monosaccharides and furfural, under the action of the alkaline solution. This naturally hindered the self-adhesive effect of the wood shavings. Furthermore, without alkaline pretreatment, the wood shavings could not form the micro-nano pore structure on the bamboo fiber surface, thus reducing the specific surface area of ​​the wood shavings. This decreased the sodium silicate loading and the self-adhesive physical bonding effect, resulting in poor formation of the water-resistant protective film and a suboptimal self-adhesive effect.

[0085] As can be seen from Table 1, in Comparative Example 2, which did not undergo the sodium silicate impregnation step, the sodium silicate system forms a strong and dense protective film under the thermal effects of molding, which has extremely strong sealing and thermal stability, and can significantly improve waterproof, fireproof and weather resistance. Therefore, the water resistance and flame retardant and smoke-suppressing performance of Comparative Example 2 are far inferior to those of Example 1.

[0086] As shown in Table 1, Comparative Example 3 differs from Example 2 only in the molding temperature, which is 130°C and 200°C respectively. Because the sodium silicate system can only undergo continuous temperature-triggered condensation reaction under suitable high temperature conditions, the number of small silicate ions in the structure is reduced, while the number of two-dimensional and three-dimensional large silicate ions increases, resulting in less dehydration from the polymerization reaction. Therefore, an extremely dense protective film layer can be formed on the product surface. Conversely, if the temperature is too low, the system dehydration is incomplete, the degree of polymerization of silicate anions is small, and more water is generated during the curing process, resulting in a loose film with many pores, which directly affects the weather resistance of the product.

[0087] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a highly flame-retardant and highly waterproof self-adhesive reconstituted bamboo substrate, characterized in that: Includes the following steps: S1, the dried bamboo shavings are subjected to benzene alcohol extraction treatment, washed, and the extracted shavings unit is obtained; the benzene alcohol extraction treatment includes the following steps: the dried bamboo shavings are mixed with benzene alcohol mixture and then treated under microwave radiation intensity of 80~100W for 30~60min, and then extracted under water bath conditions for 1~2 hours. S2, the extracted wood shavings are pretreated with an alkaline solution to obtain pretreated wood shavings; the alkaline pretreatment includes the following steps: the extracted wood shavings are placed in a 5-20 wt% alkaline solution and chemically pretreated at a temperature of 140-160℃ for 0.5-1 h to obtain pretreated wood shavings; the alkaline pretreatment is used to selectively remove hemicellulose and some lignin from the wood shavings; the ratio of the wood shavings to the alkaline solution is 1:5-10. S3, after drying and equilibration, the pretreated wood shavings are immersed in a sodium silicate aqueous solution to obtain the immersed wood shavings; the immersion treatment includes the following steps: placing the dried pretreated wood shavings in a 5~30wt% sodium silicate aqueous solution, maintaining it at a temperature of 40~60℃ for 1~2 hours, and then taking it out to obtain the immersed wood shavings; the immersion treatment is used to load sufficient sodium silicate into the cell wall pore structure of the wood shavings. S4. After the impregnated wood shavings are dried and balanced, they are molded and molded under conditions of 150~200℃ and 10~45MPa. After cooling, they are demolded to obtain bamboo self-adhesive reconstituted material.

2. The manufacturing method according to claim 1, characterized by: In step S1, the dried bamboo shavings include the following preparation steps: bamboo raw materials are made into bamboo shavings and dried to an air-dry state to obtain dried bamboo shavings.

3. The manufacturing method of claim 1, wherein: In step S1, the material-to-liquid ratio of the dried bamboo shavings and benzene alcohol mixture is 1:20~50.

4. The manufacturing method according to any one of claims 1 to 3, characterized in that: In step S4, the holding time for the molding process is 20-70 minutes; after demolding, curing and machining processes are also included.

5. A highly flame-retardant and highly waterproof self-adhesive reconstituted bamboo material, characterized in that: The bamboo material self-adhesive reconstituted material Prepared by the manufacturing method according to any one of claims 1 to 4.

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