Method for bonding bamboo and wood materials without adhesive at room temperature and under micro-pressure and application thereof

Abstract

The application discloses a method for gluing-free bonding of wood under micro-pressure at room temperature and application thereof, and relates to the technical field of wood processing. The method comprises the following steps: (1) wood surface treatment: partially removing part of lignin and hemicellulose to form an exposed wood cellulose layer on the surface of the wood; (2) fiber swelling treatment: performing swelling treatment on the wood fiber layer of the surface to be glued to disperse the fibers into fine fibers or micro fibers and make them uniformly distributed; and (3) micro-pressure gluing: applying micro-pressure not greater than 800 Pa at room temperature to bond the wood surfaces treated through the above steps for at least 24 h. The method for gluing-free bonding of wood does not need to use adhesive, can reduce production cost, and can avoid the negative influence of the adhesive on the environment and human health, and the method can not only improve production efficiency, but also help to produce more environmentally-friendly products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial board production and raw wood processing, and particularly relates to a method for non-glue bonding of bamboo-wood materials under room temperature and micro-pressure and application thereof. BACKGROUND

[0002] With the increasing emphasis on environmental protection and sustainable development worldwide, the field of wood processing and utilization is facing unprecedented challenges and opportunities. Traditional wood bonding technology basically relies on chemical adhesives, such as urea-formaldehyde resin, phenol-formaldehyde resin, and polyvinyl acetate. Although these adhesives can provide good bonding performance, their use has the following major problems: (1) Environmental pollution: The production and use of chemical adhesives may release harmful substances, causing environmental pollution. (2) Health risks: Especially formaldehyde-containing adhesives, long-term exposure can pose a threat to human health. Among them, the formaldehyde-based resin widely used in the artificial board industry accounts for 80% of the amount of wood glue due to its excellent bonding performance and low cost. Wood products and formaldehyde release have basically been equated. (3) Resource consumption: The production of traditional adhesives often relies on non-renewable resources such as petroleum, which is contrary to the trend of sustainable development. (4) Recycling difficulties: Wood products using chemical adhesives are difficult to recycle, which is not conducive to resource recycling. In view of the above problems, biomass adhesives derived from traditional petrochemical sources have emerged. Soy protein-based adhesives based on plant proteins, tannin-based adhesives based on natural polyphenols, and adhesives based on lignin, cellulose, and other wood processing by-products. However, according to the current research results, the performance of biomass adhesives is not stable in an environment with large changes in humidity and temperature, and the water resistance is poor. Compared with some synthetic adhesives, the bonding strength of biomass adhesives is not high, especially in applications that bear heavy loads, which cannot be popularized. Although the raw materials are renewable, energy consumption and cost control during production are also challenges. Therefore, developing an environmentally friendly and efficient non-glue wood bonding technology has become another direction in the field of wood processing.

[0003] The inspiration for non-glue bonding has existed since ancient times. Using screws, nails, and mortise and tenon joints to fix and connect wood pieces is the earliest non-glue technology, but this technology cannot be applied to modern artificial board manufacturing. The current mainstream non-glue technology, such as wood welding technology, uses high temperature and high pressure to soften the lignin on the surface of the wood, rearrange and solidify it, and thus achieve bonding between the wood. This method has been used to manufacture composite boards such as fiberboard and particleboard. However, the production process is relatively complex, and the bonding strength is not high, which is its biggest shortcoming. This makes non-glue bonding represent the trend of the wood processing industry towards more environmentally friendly and more sustainable development, but it is still in the early stages of research and utilization.

[0004] The breakthrough of non-adhesive bonding lies in the full use of the composition and structural characteristics of wood itself for targeted development. Among them, wood cellulose, as the most abundant organic polymer compound in wood, has good chemical stability, biocompatibility and renewability, making it an ideal natural adhesive raw material. Many researchers have developed chemically modified carboxymethylated, sulfonated or esterified cellulose adhesives, which enhance their water solubility and bonding performance. There are also cellulose nanocrystals (CNC) extracted from wood used as adhesives, which have high specific surface area and strengthening effect to improve the mechanical properties and durability of the bonded materials. Among them, the most special is cellulose microfibril (CNF), which is extracted from wood by mechanical or chemical methods. Due to its origin from natural wood, it has a very high affinity with the wood matrix material. This affinity enables CNF to effectively produce physical adsorption and chemical bonding with the wood surface. Cellulose microfibrils can penetrate into the micropores and interstitial spaces of the wood surface during the bonding process, forming an effect similar to mechanical anchoring. Cellulose microfibrils have the ability to self-assemble in water and can form a network structure similar to a gel. This network structure can fill the micro-unevenness of the bonding interface, increase the contact area, and also form a uniform distribution at the bonding interface, greatly enhancing the mechanical properties and durability of the bonding interface.

[0005] Such a large number of advantages inspired the inventors to develop non-adhesive bonding technology. Since cellulose microfibrils are derived from wood, it is better to form a microfibril filament distribution directly on the bonding surface after being extracted from wood than to use it as an adhesive. Therefore, the present invention forms a microfibril filament layer similar to CNF on the bonding surface through pretreatment of the wood surface, and makes it uniformly distributed on the wood bonding surface. Moreover, the bonding layer is native to the wood tissue, ensuring the uniformity and mechanical stability of the bonding surface. The present invention successfully realizes non-adhesive bonding of wood, and the shear strength of the wood product bonding surface obtained is close to or exceeds the strength of many traditionally bonded wood with adhesives. The main advantages of this technology include: (1) environmental protection: completely avoids the use of chemical adhesives, greatly reducing the emission of harmful substances. (2) high performance: provides a wood bonding solution comparable to traditional adhesive bonding strength through the combination of wood fibrils. (3) low cost and high practicality: the reagents and equipment required for this bonding method are low-cost industrial products, there are no special requirements for the site, and the operation is simple and easy to implement, with low popularization difficulty. (4) wide application potential: this technology is not limited to specific types of wood and is expected to be widely used in plywood manufacturing, furniture manufacturing, building material assembly and other fields.

[0006] At present, there is a lack of a low-cost method for non-adhesive bonding of bamboo-wood materials at room temperature under micro-pressure and its application. SUMMARY

[0007] The present application aims to provide a method for producing a low-cost bamboo-wood material bonded without glue under room temperature and micro-pressure and an application thereof.

[0008] To solve the problems of the prior art, the present application adopts the technical scheme as follows: the first aspect of the present application provides a method for producing a bamboo-wood material bonded without glue under room temperature and micro-pressure.

[0009] The second aspect of the present application provides an application of the method for producing a bamboo-wood material bonded without glue under room temperature and micro-pressure in preparing artificial boards or glued raw wood.

[0010] The method for producing a bamboo-wood material bonded without glue under room temperature and micro-pressure of the present application comprises the following steps: bonding separated wood materials without using glue;

[0011] (1) wood surface treatment: removing part of lignin and hemicellulose by chemical or physical means to form an exposed wood cellulose layer on the surface of the wood to be bonded;

[0012] (2) fiber filament swelling treatment: performing swelling treatment on the wood cellulose layer of the surface to be bonded to disperse the fiber filaments into fine fiber filaments or micro-filaments and uniformly distribute them;

[0013] (3) micro-pressure bonding: applying micro-pressure not greater than 800 Pa at room temperature to bond the wood surfaces treated in the above steps for at least 24 h to complete the bonding between the wood.

[0014] Further, in step (1), hydrogen peroxide and 10% wt sodium hydroxide are alternately brushed at an interval of 30 min under ultraviolet lamp irradiation, the total treatment time is 12-16 h, and deionized water is used to remove the chemical reagents after the irradiation treatment is completed. The purpose of step (1) is to partially remove lignin and expose the fiber filaments. Any lignin removal method that can achieve the same effect is within the scope of the claims and is not limited to the above lignin removal reagents and reaction systems.

[0015] Further, in step (1), the ultraviolet lamp irradiation condition is that the bonding surface is within 100 cm from the lamp tube, and the irradiation intensity value should be greater than or equal to 70 μW / cm 2 .

[0016] Further, in step (2), the bonding surface treated in step (1) is soaked in a mixture of sodium hydroxide and urea for 10 min, the soaking depth is not more than 1 mm, then it is frozen at-18 ℃ to-25 ℃ for 3-6 h, taken out and placed at room temperature, and deionized water is used to remove the chemical reagents. The purpose of step (2) is to dissolve and expand the fiber filaments into micro-fiber filaments. Any fiber filament swelling method that can achieve the same effect is within the scope of the claims and is not limited to the above fiber filament swelling reagents and reaction systems.

[0017] Further, in step (2), sodium hydroxide is mixed with urea to consist of the following components by weight fraction:

[0018] Deionized water 72-80 parts,

[0019] Sodium hydroxide 12-16 parts,

[0020] Urea 8-12 parts.

[0021] Further, in step (3), micro-pressure bonding is carried out at a temperature of 0-50℃. After the wood surface to be bonded is treated by steps (1) and (2), the wood fiber filaments are split into micro-filaments, and the surface of the micro-filaments contains a large number of hydroxyl groups.

[0022] Further, in step (3), the bonded wood is raw wood or bamboo, and the bonding surface can be any cross-sectional shape, and the bonding surface is smooth and free of resin residues, regardless of the type of wood, and the bonding strength depends on the exposure of the wood fiber filament layer of the bonding surface and the uniformity of the swelling and dispersion.

[0023] The method of the present application for bonding bamboo and wood materials at room temperature under micro-pressure without glue has the following advantages:

[0024] Beneficial effects: The method of the present application for bonding wood without glue does not require the use of adhesives, and the bonding conditions are simple, with good bonding performance, wide application scenarios, and good applicability to different types of wood and different forms of wood products, which not only improves production efficiency but also helps to produce more environmentally friendly products.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] (1) No need to use adhesives: The present application uses a unique method to achieve glue-free bonding of wood without the use of adhesives. The chemical reagents, ultraviolet lamps and refrigerators used are inexpensive industrial products, the bonding process is carried out under room temperature and micro-pressure conditions, which is safe and has no special requirements for the implementation site, and is simple and easy to operate, which can be used widely at low cost, and also avoids the negative impact of adhesives on the environment and human health.

[0027] (2) Good bonding effect: The present application forms a native micro-filament layer on the surface of the modified wood, and achieves high bonding strength by relying on the physical effect of the interlocking anchoring of the micro-filaments and the bonding of the hydroxyl groups on the surface of the micro-filaments. The shear strength of the bonded surface of the wood product obtained is about 2MPa, which is comparable to the main chemical adhesives. The bonding effect of this method is better than that of existing glue-free bonding of wood, especially in environments with high humidity or large temperature changes, the bonded wood is less likely to crack or fall off, improving the stability and durability of the wood product.

[0028] (3) Wide application potential: The wood bonding method of the present application is simple to operate and does not require special equipment, making it suitable for large-scale industrial application. Compared with existing methods of glue-free bonding of wood, the method of the present application is easier to popularize and apply. The technology is not limited to a specific type of wood and does not depend on special site conditions, and is expected to be widely used in the fields of plywood manufacturing, furniture manufacturing, building material assembly, etc.

[0029] (4) Green and environmentally friendly: Since the present application does not require the use of adhesives, although hydrogen peroxide, sodium hydroxide and urea are used in the gluing process, there is no chemical residue after washing with deionized water, and the final glued product is a pure wood product, which can be completely recycled, greatly reducing the emission of harmful substances. Therefore, it will not have a negative impact on the environment and meet the current environmental protection requirements. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0031] Figure 1 The photos of the raw bamboo of Dendrocalamus latiflorus and the bamboo treated by the three steps of Example 4 of the present application.

[0032] Figure 2 The SEM photo of the surface of Dendrocalamus latiflorus of Example 4 of the present application magnified 200 times without treatment.

[0033] Figure 3 The SEM photo of the surface of Dendrocalamus latiflorus of Example 4 of the present application magnified 200 times after step (1) removing part of lignin for gluing surface.

[0034] Figure 4 The SEM photo of the surface of Dendrocalamus latiflorus of Example 4 of the present application magnified 200 times after step (2) fiber filament swelling for gluing surface.

[0035] Figure 5 The SEM photo of the surface of Dendrocalamus latiflorus of Example 4 of the present application magnified 50 times after step (2) fiber filament swelling for gluing surface. DETAILED DESCRIPTION

[0036] In order to make the technical problems, technical solutions and beneficial effects of the present application more clear, the following will further describe the present application with examples. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0037] In the present application, the term "and / or", describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0038] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of the items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.

[0039] It should be understood that in various embodiments of the present application, the size of the sequence number of the above processes does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0040] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0041] The weight of the related components mentioned in the specification of the embodiments of the present application can not only refer to the specific content of each component, but also represent the weight ratio relationship between each component, therefore, as long as the content of the related components in the specification of the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the specification of the embodiments of the present application. Specifically, the mass mentioned in the specification of the embodiments of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0042] The first aspect of the present application provides a method for bonding bamboo and wood materials without adhesive at room temperature and under micro-pressure, comprising the following steps:

[0043] In step (1), wood surface treatment: part of lignin and hemicellulose is removed by chemical or physical means to form an exposed lignocellulose layer on the surface of the wood to be bonded;

[0044] In step (2), fiber filament swelling treatment: swelling treatment is performed on the wood fiber filament layer of the surface to be glued, so that the fiber filaments are dispersed into fine fiber filaments or micro fiber filaments and uniformly distributed;

[0045] In step (3), micro-pressure gluing: micro-pressure not greater than 800 Pa is applied at room temperature, and the wood surfaces treated in the above steps are laminated for at least 24 h to complete the adhesion between the wood. The micro-pressure gluing is performed at a temperature of 0-50°C.

[0046] In some embodiments, in step (1), hydrogen peroxide and 10% wt sodium hydroxide are alternately brushed at an interval of 30 min under ultraviolet lamp irradiation. The ultraviolet lamp irradiation condition is that the surface to be glued is within 100 cm from the lamp tube, and the irradiation intensity value should be greater than or equal to 70 μW / cm 2 . The purpose of step (1) is to partially remove lignin and expose fiber filaments. Any lignin removal method that can achieve the same effect is within the scope of the claims and is not limited to the above lignin removal reagents and reaction systems.

[0047] In some embodiments, in step (1), hydrogen peroxide and 10% wt sodium hydroxide are alternately brushed at an interval of 30 min under ultraviolet lamp irradiation, and the total treatment time is 12 h. The ultraviolet lamp irradiation condition is that the surface to be glued is within 100 cm from the lamp tube, and the irradiation intensity value should be greater than or equal to 70 μW / cm 2 .

[0048] In some embodiments, in step (1), hydrogen peroxide and 10% wt sodium hydroxide are alternately brushed at an interval of 30 min under ultraviolet lamp irradiation, and the total treatment time is 14 h. The ultraviolet lamp irradiation condition is that the surface to be glued is within 100 cm from the lamp tube, and the irradiation intensity value should be greater than or equal to 70 μW / cm 2 .

[0049] In some embodiments, in step (2), the surface to be glued treated in step (1) is soaked in a sodium hydroxide and urea mixed solution for 10 min, the soaking depth is not more than 1 mm, then it is frozen at -25°C for 6 h, taken out and placed at room temperature, and the chemical reagents are removed using deionized water. The purpose of step (2) is to swell the fiber filaments into micro fiber filaments. Any fiber filament swelling method that can achieve the same effect is within the scope of the claims and is not limited to the above fiber filament swelling reagents and reaction systems.

[0050] The sodium hydroxide and urea mixed solution is composed of the following components by weight fraction:

[0051] Deionized water 78 parts,

[0052] Sodium hydroxide 12 parts,

[0053] Urea 9 parts.

[0054] In some embodiments, in step (2), the surface to be glued of the wood treated in step (1) is soaked in the sodium hydroxide and urea mixture for 10 minutes, with a soaking depth of no more than 1 mm, and then frozen at -20°C for 3 hours, taken out and placed at room temperature, and the chemical reagent is removed using deionized water.

[0055] The sodium hydroxide and urea mixture is composed of the following components in parts by weight:

[0056] Deionized water 72 parts,

[0057] Sodium hydroxide 16 parts,

[0058] Urea 12 parts.

[0059] In some embodiments, in step (2), the surface to be glued of the wood treated in step (1) is soaked in the sodium hydroxide and urea mixture for 10 minutes, with a soaking depth of no more than 1 mm, and then frozen at -20°C for 3 hours, taken out and placed at room temperature, and the chemical reagent is removed using deionized water.

[0060] The sodium hydroxide and urea mixture is composed of the following components in parts by weight:

[0061] Deionized water 80 parts,

[0062] Sodium hydroxide 14 parts,

[0063] Urea 8 parts.

[0064] In some embodiments, in step (3), after the surface to be glued of the wood is treated in steps (1) and (2), the wood fiber filaments are cracked into microfilaments, and the surface of the microfilaments contains a large number of hydroxyl groups.

[0065] In some embodiments, in step (3), the glued wood is a raw wood, and the surface to be glued can be any cut surface form, and the glued surface is smooth and free of resin residues, regardless of the type of wood, and the bonding strength depends on the exposure suitability of the wood fiber filament layer of the surface to be glued and the uniformity of swelling and dispersion.

[0066] In some embodiments, in step (3), the glued wood is a bamboo, and the surface to be glued can be any cut surface form, and the glued surface is smooth and free of resin residues, regardless of the type of bamboo, and the bonding strength depends on the exposure suitability of the wood fiber filament layer of the surface to be glued and the uniformity of swelling and dispersion.

[0067] The second aspect of the present application provides a method for gluing bamboo and wood materials at room temperature and under micro-pressure without using adhesives, and the method is used in the preparation of artificial boards or glued raw wood.

[0068] Example 1

[0069] Select the thickness of 2mm poplar veneer to make three-layer plywood, and process one side of the face plate as the bonding surface, and process two sides of the core plate as the bonding surface.

[0070] The method for gluing-free bonding of bamboo-wood materials at room temperature under micro-pressure of the application comprises the following steps:

[0071] In step (1), wood surface treatment: use hydrogen peroxide and 10%wt sodium hydroxide to alternately brush the wood bonding surface every 30 minutes, and use a UV lamp to irradiate within 100cm above the wood to accelerate the surface reaction rate, and react for 12 hours.

[0072] In step (2), fiber filament swelling treatment: immerse the bonding surface treated in the first step in a mixture of deionized water 73 parts, sodium hydroxide 15 parts, and urea 12 parts by mass for 10 minutes, and the immersion liquid level should not exceed 1mm. After immersion, the wood is frozen at-18℃ for 3 hours, then taken out and placed at room temperature, and then washed with deionized water to remove the chemical reagents.

[0073] In step (3), micro-pressure gluing: place the poplar veneer treated in step (2) into a vulcanizing machine according to the three-layer plate manufacturing process, apply 800Pa pressure at a temperature of 50℃ on the upper and lower plates, and adhere for 24 hours to obtain the plywood.

[0074] Example 2

[0075] The difference between Example 2 and Example 1 is that 2mm thick elm veneer is selected to make three-layer plywood, and one side of the face plate is treated as the bonding surface, and two sides of the core plate are treated as the bonding surface.

[0076] The method for gluing-free bonding of bamboo-wood materials at room temperature under micro-pressure of the application comprises the following steps:

[0077] In step (1), wood surface treatment: use hydrogen peroxide and 12%wt sodium hydroxide to alternately brush the wood bonding surface every 25 minutes, and use a UV lamp to irradiate within 80cm above the wood to accelerate the surface reaction rate, and react for 14 hours.

[0078] In step (2), fiber filament swelling treatment: immerse the bonding surface treated in the first step in a mixture of deionized water 74 parts, sodium hydroxide 14 parts, and urea 12 parts by mass for 10 minutes, and the immersion liquid level should not exceed 1mm. After immersion, the wood is frozen at-20℃ for 3 hours, then taken out and placed at room temperature, and then washed with deionized water to remove the chemical reagents.

[0079] In step (3), micro-pressure bonding: the yew single board treated in the second step is put into a vulcanizing machine according to a three-layer board manufacturing process, 800 Pa pressure is applied to the upper board and the lower board at a temperature of 50 DEG C, and bonding is performed for 26 h to obtain the plywood.

[0080] Example 3

[0081] Example 3 is different from example 1 in that: the size of the black hickory wood strip is 50*25*25mm, the bonding surface is 50*25mm, the bonded product is made, the wood product can be used as a basic unit of bonded wood, or as a demonstration example of furniture manufacturing.

[0082] The method for gluing bamboo-wood material without glue under room temperature and micro-pressure of the application comprises the following steps:

[0083] In step (1), wood surface treatment: the bonding surface is alternately brushed with hydrogen peroxide and 12%wt sodium hydroxide every 20 min, and the bonding surface is irradiated by a UV lamp within a range of 100 cm above the bonding surface to accelerate the surface reaction rate, and the reaction is performed for 15 h.

[0084] In step (2), fiber filament swelling treatment: the bonding surface treated in the first step is soaked in a mixed solution of deionized water 72 parts, sodium hydroxide 16 parts and urea 12 parts by mass for 10 min, and the soaking liquid level is not more than 1 mm. After soaking, the wood is frozen at-20 DEG C for 5 h, then taken out and placed at room temperature, and then washed with deionized water to remove the chemical reagents.

[0085] In step (3), micro-pressure bonding: two black hickory wood pieces treated in the second step are clamped and put into an oven, dried and bonded at a temperature of 60 DEG C for 36 h to obtain a black hickory wood product.

[0086] Example 4

[0087] Example 4 is different from example 1 in that:

[0088] As shown in Figures 1 to 4 , a single-lap bonding piece is made by selecting a size of 100*25*2mm bamboo single board, the lap area is 25*12.5mm, the lap surface is the bonding surface to be treated, and the bamboo can be seen Figure 1 , and the enlarged view of the surface of the original bamboo can be seen Figure 2 .

[0089] The method for gluing bamboo-wood material without glue under room temperature and micro-pressure of the application comprises the following steps:

[0090] In step (1), wood surface treatment: using hydrogen peroxide and 10% wt content of sodium hydroxide to brush the bamboo surface to be glued every 20 min, and using ultraviolet lamp to irradiate within 100 cm above the surface to accelerate the surface reaction rate, and the reaction time is 12 h. Figure 3 .

[0091] In step (2), fiber filament swelling treatment: the glued surface treated in the first step is soaked in a mixed solution of deionized water 72 parts, sodium hydroxide 16 parts, and urea 12 parts by mass for 12 min, and the soaking liquid height is not more than 1 mm. After soaking, the bamboo is taken out and placed at room temperature after freezing in a-18℃ environment for 4 h, and then washed with deionized water to remove the chemical reagents. Figure 4 、 5 .

[0092] In step (3), micro-pressure gluing: the bamboo lapping piece treated in step (2) is placed in a vulcanizing machine, and an 800 Pa pressure is applied at a temperature of 50℃ on the upper and lower plates, and the lapping plate is obtained after 30 h.

[0093] Regarding Example 4, the surface fiber filaments of Dendrocalamus latiflorus are exposed by step (1), and the fiber filaments are swelled into fine filaments by step (2), and the comparison with the untreated surface of Dendrocalamus latiflorus is illustrated by using the drawings.

[0094] Example 5

[0095] The difference between Example 5 and Example 1 is that a single lapping glued piece is made of a bamboo veneer with a size of 100×25×2 mm, and the lapping area is 25×12.5 mm, and the lapping surface is the glued surface to be treated.

[0096] The method for gluing bamboo and wood materials at room temperature and under micro-pressure without adhesive according to the present application comprises the following steps:

[0097] In step (1), wood surface treatment: using hydrogen peroxide and 10% wt content of sodium hydroxide to brush the bamboo surface to be glued every 30 min, and using ultraviolet lamp to irradiate within 100 cm above the surface to accelerate the surface reaction rate, and the reaction time is 16 h.

[0098] In step (2), fiber filament swelling treatment: the glued surface treated in the first step is soaked in a mixed solution of deionized water 76 parts, sodium hydroxide 14 parts, and urea 10 parts by mass for 12 min, and the soaking liquid height is not more than 1 mm. After soaking, the bamboo is taken out and placed at room temperature after freezing in a-18℃ environment for 5 h, and then washed with deionized water to remove the chemical reagents.

[0099] In step (1), micro-pressure bonding: the second step treated bamboo material lap joint is placed in a vulcanizing machine, 800 Pa pressure is applied under the condition of 50 ℃ temperature of the upper plate and the lower plate, and the lap joint plate is prepared by bonding for 30 h.

[0100] Test Example 1

[0101] The plywood prepared in Examples 1-2 was respectively taken, and the physical and mechanical properties of the board were tested according to the national standard GB / T 17657-2022 "Test methods for physical and mechanical properties of wood-based panels and veneered wood-based panels", and the mechanical strength test standard for type II plywood was used. The specific results are as follows:

[0102] The wet bonding strength of the test piece after soaking in 63 ℃ hot water for 3 hours is 1.0-1.3 MPa, which meets and exceeds the national standard (≥0.7 MPa).

[0103] Test Example 2

[0104] The wood bonding product prepared in Example 3 was taken, and the tensile shear strength of the bonding surface was tested using a mechanical testing machine. Since the bonding test of the test piece is of arbitrary shape, there is no relevant national standard, and the tensile shear strength test refers to the national standard GB / T 26899-2022 "Structural integrated wood", and the E44 epoxy resin is used as comparative test piece 1, and the urea-formaldehyde resin with a molar ratio of formaldehyde to urea F / U of 1.2 is used as comparative test piece 2. The specific results are as follows:

[0105] The dry shear strength of the test piece is 3.1-3.6 MPa, the dry shear strength of the urea-formaldehyde resin test piece is 1.2-1.5 MPa, and the dry shear strength of the epoxy resin test piece is 7.7-8.2 MPa. The wood bonding product of the present application is better than the urea-formaldehyde resin and weaker than the bonding strength of the epoxy resin.

[0106] Test Example 3

[0107] The bamboo single lap bonding joint prepared in Examples 4-5 was respectively taken, and the bonding tensile shear strength of the board was tested according to the national standard GB / T 7124-2008 "Determination of tensile shear strength of adhesives", and the urea-formaldehyde resin with a molar ratio of formaldehyde to urea F / U of 1.2 was used as a comparative test piece. The specific results are as follows:

[0108] The dry shear strength of the test piece is 1.6-1.9 MPa, and the dry shear strength of the urea-formaldehyde resin test piece is 1.3-1.5 MPa. The bonding strength of the adhesive-free bonded wood of the present application is stronger than that of the urea-formaldehyde resin.

[0109] Comparative Example 1

[0110] Patent number CN202011534574.9, entitled "A Method for Preparing Reconstituted Veneer Without Glue and its Preparation," describes a process where the veneer is first deligninized, then the delignin-treated samples are stacked and cold-pressed at a pressure of 3-6 MPa, followed by hot-pressing at 100°C and a pressure of 8-10 MPa to obtain the reconstituted veneer. As can be seen from the above description, this patent differs from our invention in both materials and final product. Our invention does not limit the type or form of wood; it can even use bamboo. Our invention applies for a glue-free bonding method, not the production of a specific product. Furthermore, regarding the bonding principle, the comparative patent converts wood into a cellulose polymer and then compresses it to obtain reconstituted wood, while our patent's bonding principle is the physical entanglement and chemical bonding of microfibers. Finally, the comparative patent requires more stringent process conditions and uses high pressure to prepare samples, while the feature of this patent is a glue-free bonding method under room temperature and micro-pressure conditions. Therefore, the comparative patent and this invention are completely different.

[0111] Comparative Example 2

[0112] The patent, with patent number CN202210165052.9, is titled "A Method for Glue-Free Bonding of Wood-based Panels." This patent primarily targets engineered wood products, mainly plywood, particleboard, and fiberboard. The bonding mechanism involves boiling with sodium hydroxide at 150°C, causing lignin to break down and soften. Subsequently, at 90°C, glyoxal undergoes addition condensation with lignin phenolic substances, reacting in situ on the wood surface to form hydroxyphenolic prepolymers. Finally, under hot pressure at 200°C and 4MPa, the prepolymer rapidly polymerizes to form a large-molecule three-dimensional network thermosetting resin, achieving bonding. While this patent can produce plywood, it is not applicable to fiberboard and particleboard. Furthermore, the core advantage of this patent lies in its room temperature and low-pressure conditions. The preparation process uses temperatures ranging from -20°C to 50°C and pressures below 800Pa, a stark contrast to the high-temperature and high-pressure conditions of the comparative patent. Finally, the bonding mechanism of this patent is the physical entanglement and chemical bonding of microfibers, which has no similarity to the prepolymer resin formation scheme of the comparative patent. Therefore, the comparative patent is completely different from this invention.

[0113] Comparative Example 3

[0114] Patent No. CN202310400603.X, the patent name is based on the preparation of no glue bamboo plywood integrated material by rotary welding technology. The finished product of this patent is limited to bamboo plywood, the main process is that the bamboo tenon is drilled into the pre-opened hole at high speed, and the glued interface is formed by using the movement friction of the bamboo tenon head to cool and solidify. The invention can also glue the bamboo board, but the glued surface needs to be pretreated, and the glued layer formed by the swelling and dispersion of microfilaments is used. A series of chemical and physical modifications are carried out during the pretreatment and pressing process of the glued surface. The obtained gluing strength is equivalent to that of the mainstream chemical adhesive. The comparative example and the patent have great differences in the preparation object, gluing process and gluing mechanism, and the comparative patent does not explain the specific value of the gluing strength, so the two kinds of glue-free bonding methods cannot be compared. Therefore, the comparative patent and the invention are completely different.

[0115] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and the scope of protection of the present application is defined by the appended claims, the specification and its equivalents.

Claims

1. A method for non-adhesive bonding of bamboo-wood materials under room temperature and micro-pressure, characterized in that The method comprises the following steps: bonding separated wood materials without using adhesive; (1) Surface treatment of bamboo-wood materials: removing part of lignin and hemicellulose by chemical or physical means to form an exposed wood cellulose layer on the surface of the bamboo-wood materials to be bonded; under ultraviolet light irradiation, hydrogen peroxide and 10 wt% sodium hydroxide are alternately brushed every 30 minutes, the total treatment time is 12-16 hours, and after the irradiation treatment is completed, the chemical reagents are removed using deionized water; (2) Fiber swelling treatment: the wood fiber layer of the surface to be bonded is subjected to swelling treatment to disperse the fibers into fine fibers or microfibers and uniformly distribute them; the surface to be bonded treated in step (1) is soaked in a mixture of sodium hydroxide and urea for 10 minutes, the soaking depth is not more than 1 mm, then it is frozen at-18 to-25°C for 3-6 hours, taken out and placed at room temperature, and the chemical reagents are removed using deionized water; (3) Micro-pressure bonding: applying a micro-pressure of not more than 800 Pa at room temperature to paste the surface of the bamboo-wood materials treated in the above steps for at least 24 hours to complete the bonding between the bamboo-wood materials.

2. The method for bamboo-wood material without adhesive bonding under room temperature and micro-pressure according to claim 1, characterized in that: In step (1), the ultraviolet lamp irradiation conditions are that the distance between the bonding surface and the lamp tube is within 100 cm, and the irradiation intensity value is greater than or equal to 70 μW / cm 2 .

3. The method for bamboo-wood material without adhesive bonding under room temperature and micro-pressure according to claim 1, characterized in that: In step (2), the mixture of sodium hydroxide and urea consists of the following components by weight fraction: Deionized water 72-80 parts, Sodium hydroxide 12-16 parts, Urea 8-12 parts.

4. The method for bamboo-wood material without adhesive bonding under room temperature and micro-pressure according to claim 1, characterized in that: In step (3), the micro-pressure bonding is carried out at a temperature of 0-50°C.

5. The method for bamboo-wood material without adhesive bonding under room temperature and micro-pressure according to claim 1, characterized in that: In step (3), the bamboo-wood materials to be bonded are original wood or bamboo, the surface to be bonded can be any cut surface form, the bonded surface is smooth and free of resin residues, the type of bamboo-wood materials is not limited, the bonding strength depends on the exposure suitability of the wood fiber layer of the surface to be bonded and the uniformity of the swelling dispersion.

6. Use of the method for bonding bamboo-wood materials without adhesive at room temperature and under micro-pressure according to any one of claims 1 to 5 in the preparation of artificial board or bonded original wood.

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