Bamboo nail and preparation method and application thereof

Abstract

The invention discloses a bamboo nail and a preparation method and application thereof.The preparation method comprises the following steps that S1, mature moso bamboos or small-diameter bamboo materials are selected and processed into bamboo strips through subdivision and joint removal treatment; s2, the bamboo canes are defibered and processed into bamboo fiber bundles or bamboo filaments; s3, drying the obtained bamboo fiber bundles or bamboo filaments; s4, the dried bamboo fiber bundles or bamboo filaments are soaked in mixed resin for a structure, and then drying or air-drying is conducted; s5, the dried or air-dried bamboo fiber bundles or bamboo filaments are directionally and evenly laid into a blank, and the blank is subjected to hot-pressing curing forming to form a bamboo composite board; s6, the bamboo composite board is divided into square bamboo strips through a wafer separator; s7, the square bamboo canes are made into round bamboo sticks through a forming machine; and S8, the round bamboo stick is subjected to length fixing, sharpening and other machining, and the bamboo nail is obtained. The bamboo nail product is low in raw material cost, wide in selection range and simple and reliable in preparation method, and can be widely applied to connection of wood structural members and wood components.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wood component or wood product part connecting, in particular to a bamboo nail and its preparation method and application. BACKGROUND

[0002] The environmental problems caused by global warming are becoming increasingly serious, and the development of green energy-saving and environmentally friendly wood structure buildings has become an important way to slow down carbon emissions. Wood nail is a new type of connecting piece developed by Austria BECK company in recent years, mainly made of beech veneer by laminated composite processing, used to replace steel nails, iron nails and self-tapping screws, etc. for connecting various wood components. The product is low-carbon and environmentally friendly. At the same time, it is convenient to use special nail gun, and the wood component is natural and beautiful. It is also convenient to process and recycle. However, due to the narrow selection range of raw materials, slow growth of beech, harvesting restrictions and high transportation costs, the price of this type of wood nail is high, so it is urgent to develop alternative wood nail materials. In recent years, more and more attention has been paid to the high-value utilization of bamboo resources at home and abroad, but there is no related technology report on the preparation of bamboo nails using bamboo or bamboo composite materials.

[0003] China's bamboo grows in short cycles and is abundant in resources. With the advantages of straight fibers, high strength, good impact resistance and toughness, and low price, it has the potential to produce bamboo nails to replace imported beech wood nails, steel nails, iron nails and self-tapping screws. If bamboo nail products can be developed and raw materials can be localized, the comprehensive utilization efficiency and added value of bamboo can be greatly improved, and the application range of bamboo can be broadened. SUMMARY

[0004] The technical problem to be solved by the present application is the narrow selection range of raw materials for the connecting piece wood nail of the existing wood component or wood product part, and the high manufacturing cost. In order to overcome the defects of the above prior art, the present application provides a bamboo nail and its preparation method and application.

[0005] The first object of the present application is to provide a preparation method of a bamboo nail, comprising the following steps: S1, selecting mature bamboo or small-diameter bamboo, and processing into bamboo strips through splitting and debarking; S2, processing the bamboo strips into bamboo fiber bundles or bamboo filaments through defibration; S3, drying the obtained bamboo fiber bundles or bamboo filaments; S4, dipping the dried bamboo fiber bundles or bamboo filaments into a mixed resin for structure, and then drying or airing; S5, uniformly laying the dried or aired bamboo fiber bundles or bamboo filaments in a direction to form a blank, and then hot-pressing and curing to form a bamboo composite board; S6, splitting the bamboo composite board into square bamboo strips by a splitting machine; S7. The square bamboo strips are formed into round bamboo sticks using a molding machine; S8. The circular bamboo stick is processed into a fixed length and sharpened to obtain a bamboo nail.

[0006] Compared with existing technologies, this application has the following advantages: it uses traditional bamboo as the raw material, which is low in cost and has a wide range of choices. The processing method is simple and reliable, and the production cost is low. The products can be widely used to replace wooden nails, steel nails, iron nails and self-tapping screws for the connection of various wooden structural components and wooden product parts. It is green and environmentally friendly, the products are recyclable, and it helps to reduce carbon emissions, with significant economic, social and ecological benefits.

[0007] In one possible implementation, the drying control in step S3 aims to achieve a moisture content of 6-12%.

[0008] In one possible implementation, the immersion time in step S4 is 5~300s, and the drying or baking is controlled to achieve a moisture content of 8~12%.

[0009] In one possible implementation, the structural resin used in step S4 comprises the following components in parts by weight: 70-90 parts of low molecular weight phenolic resin, 3-10 parts of 4114 alkaline antifungal and preservative agent, 3-10 parts of ethanol, 5-10 parts of 4-bromo-1,8-naphthalenedicarboxylic anhydride, and 5-10 parts of 2-amino-1,3-propanediol. All components are mixed evenly to obtain the structural resin.

[0010] In the above scheme, bamboo nails are made by impregnating them with a structural mixed resin. During rapid driving, the bamboo nails can interact with the lignin of the surrounding wood through frictional heat, causing it to flow and bond, thus achieving a strong connection. Simultaneously, the surface has a certain degree of roughness, which helps to improve the connection strength. The presence of an alkaline anti-mildew and anti-corrosion agent (4114) protects the bamboo nails from mold growth, thereby improving their durability.

[0011] In one possible implementation, the process parameters for hot-pressing curing in step S5 are: hot pressing at 120~155℃ and 2~5MPa pressure for 0.5~3.0 min / mm thickness. At this hot-pressing temperature, 4-bromo-1,8-naphthalenedicarboxylic anhydride and 2-amino-1,3-propanediol will first undergo alcoholysis acylation to generate 4-bromo-N (2-hydroxy-1-hydroxymethylethyl) 1,8-naphthalenedicarboxylic acid amide chain extender, which promotes the chain extension reaction (alkylation) between low molecular weight phenolic resin and lignin in bamboo fiber bundles or bamboo filaments to form an organic polymer structure with rigid naphthalene rings and low surface energy, achieving eutectic bonding and improving the strength, impact resistance, and toughness of the board.

[0012] In one possible implementation, step S8 specifically involves first placing the round bamboo stick on a length-setting machine and cutting it to a length twice the length of the bamboo nail. Then, the ends of the cut round bamboo stick are sharpened, and then the length-setting machine cuts the sharpened round bamboo stick a second time from the middle to obtain the bamboo nail. The first double-length cutting is done because the long strip is easier to fix and sharpen, and then cutting from the middle to obtain the bamboo nail is more convenient.

[0013] A second objective of this invention is to provide a bamboo nail prepared by the above-described preparation method.

[0014] In one possible implementation, the bamboo nail has a length of 50-120 mm, a diameter of 4.0-10.0 mm, and a tip angle of 30°-60°. Currently, there is no unified standard for bamboo nails domestically or internationally. However, the size of the beechwood nails used in the F60 pneumatic nail gun system of the LIGNOLOC wood nail system from the Austrian BECK connector company can be referenced, and the bamboo nails described in this invention are also designed with reference to this specification.

[0015] A third objective of the present invention is to provide the application of the aforementioned bamboo nails in the connection of wooden components or wooden product parts.

[0016] In one possible implementation, the bamboo nails are driven into the wooden components or wooden parts using an F60 pneumatic nail gun.

[0017] In the above scheme, at the moment of firing the F60 pneumatic nail gun, the local instantaneous temperature of the most concentrated energy parts, such as the impact point of the firing pin and the friction point between the nail and the wood, may exceed 150°C, or even briefly reach over 200°C. The lignin with aromatic ring structure extended by low molecular weight phenolic resin can further undergo alcoholysis to produce active groups, which then react with the wood components or wood products to form a cross-linked structure, improving the firm connection between the bamboo nail and the wood components or wood products.

[0018] The beneficial effects of this invention are as follows: 1. This invention can make full use of the abundant bamboo resources in China to prepare bamboo nails, which can replace wooden nails, steel nails, iron nails and self-tapping screws. It has a high raw material utilization rate, is easy to nail, and has low production cost. Its performance is comparable to imported beech wood nails. It is suitable for the connection and installation of various wood structure boards and components, wood products and furniture parts. The final product is green, low-carbon and environmentally friendly, and easy to recycle.

[0019] 2. The bamboo nail preparation method disclosed in this invention has not been reported domestically or internationally, and has not been commercially applied. Using bamboo nails with a length of 50-120mm allows for flexible connection of shelves of different thicknesses and types, improving product applicability.

[0020] 3. This invention can utilize and improve existing domestic bamboo board processing and bamboo skewer processing equipment, realize the localization of bamboo nails and production equipment, reduce dependence on foreign countries, and has significant economic and social benefits and industrial promotion value.

[0021] 4. High-strength bamboo nails are made from bamboo and have advantages such as corrosion resistance, easy disassembly, easy wood recycling, and light weight. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process of processing bamboo composite boards into bamboo nails according to the present invention.

[0023] Figure 2 This is a schematic diagram showing the basic dimensions of the bamboo nails of this invention. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0025] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0026] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.

[0027] See Figure 1 A method for preparing bamboo nails includes the following steps: 1) Select mature moso bamboo or small-diameter bamboo. Moso bamboo needs to be split and nodes removed to process it into bamboo strips. 2) Then, the bamboo strips or small-diameter bamboo are decomposed and processed into fiber bundles or bamboo filaments; 3) Dry the fiber bundles or bamboo strips by baking or sun-drying until the moisture content is 6-12%; 4) Impregnate the fiber bundles or bamboo filaments with the structural mixed resin for 5-300 seconds, then air-dry to control the moisture content to 8-12%. The structural mixed resin comprises the following components by weight: 70-90 parts low molecular weight phenolic resin, 3-10 parts 4114 alkaline antifungal and preservative agent, 3-10 parts ethanol, 5-10 parts 4-bromo-1,8-naphthalenedicarboxylic anhydride, and 5-10 parts 2-amino-1,3-propanediol. All components are mixed evenly to obtain the mixed resin. Thoroughly impregnate the fiber bundles or bamboo filaments with the structural mixed resin so that all cellulose or bamboo filaments are coated with the mixed resin, then dry or air-dry naturally.

[0028] 5) The fiber bundles or bamboo filaments are laid out evenly and oriented into a blank, and then hot-pressed at 120~155℃ and 2~5MPa for 0.5~3.0 min / mm thickness to solidify and form a bamboo composite board. 6) The bamboo composite board is cut into modular square bamboo strips using a wood slitting machine; 7) Square bamboo strips are formed into round bamboo sticks using a bamboo stick forming machine; 8) On the bamboo stick cutting machine, the round bamboo sticks are cut to a fixed length of twice the length of the bamboo nail; 9) Sharpen both ends of the bamboo stick, with the nail tip angle α being 30°~60°; 10) The bamboo sticks are cut twice from the middle by a length-cutting machine to obtain the final bamboo nail products. The length of the bamboo nails is 50~120mm and the diameter is 4.0~10.0mm.

[0029] The specific shape and size of the bamboo nails are as follows: Figure 2 As shown. The length L of the bamboo nail is 50~90mm and the diameter D is 4.7~5.3mm.

[0030] Preferably, the thickness of the bamboo composite board can be adjusted according to the target size of the bamboo nails.

[0031] Preferably, in step (9), the nail tip angle should be machined to 45°. This method can effectively drive the bamboo nail into the predetermined position and avoid deviation.

[0032] The present application will be further described in detail below with reference to specific embodiments.

[0033] Example 1: Preparation method and mechanical properties of bamboo nails a. First, prepare the structural mixed resin by weighing 84 parts of low molecular weight phenolic resin, 3 parts of 4114 alkaline antifungal and preservative agent, 3 parts of ethanol, 5 parts of 4-bromo-1,8-naphthalenedicarboxylic anhydride, and 5 parts of 2-amino-1,3-propanediol. Add all components to a mixing tank and stir until homogeneous to obtain the structural mixed resin.

[0034] b. After impregnating bamboo fiber bundles with mixed resin for 10 seconds and drying them, the bundles are laid out in an oriented manner and then hot-pressed at 130°C and 2MPa for 1.5 hours to obtain a 40mm thick bamboo composite board. c. The bamboo composite board is cut into square bamboo strips with a specified module of 6×6mm by a wood slitting machine; the cut bamboo strips are fed into a bamboo stick forming machine and turned into round bamboo sticks with a diameter of 5 mm. d. Place the round bamboo sticks on the length-cutting machine and cut them into 150mm long bamboo stick segments; e. Sharpen both ends of the bamboo stick segment to a 45° angle, then cut it in the middle using a length-cutting machine to obtain the finished bamboo nail. The bamboo nail is 75mm long and 5mm in diameter.

[0035] f. As a control, 10 imported beech wood nails were randomly selected and tested for mechanical properties along with 10 bamboo nails. The test results are shown in Table 1.

[0036] Table 1 Comparison of physical and mechanical properties of beech wood nails and bamboo nails from Example 1 Note: The numbers in parentheses are the standard deviations of the test samples. Table 1 shows the comparative test results of the mechanical properties of the bamboo and wooden nails prepared in Example 1. The results show that the average density of the wooden and bamboo nails is basically the same, but the density uniformity of the bamboo nails is better because the standard deviation is smaller; at the same time, the yield moment and tensile strength of the bamboo nails are higher than those of the wooden nails; the yield moment of the bamboo nails has slightly greater variability, while the tensile strength has smaller variability. This can be improved by further optimizing the resin impregnation, laying and hot pressing processes to enhance the mechanical properties of the bamboo nails.

[0037] Example 2 a. First, prepare the structural mixed resin by weighing 80 parts of low molecular weight phenolic resin, 5 parts of 4114 alkaline antifungal and preservative agent, 3 parts of ethanol, 6 parts of 4-bromo-1,8-naphthalenedicarboxylic anhydride, and 6 parts of 2-amino-1,3-propanediol. Add all components to a mixing tank and stir until homogeneous to obtain the mixed resin.

[0038] b. Bamboo fiber bundles are impregnated with mixed resin for 15 seconds and dried to 10% moisture content. After being laid in a directional manner, they are hot-pressed at 145°C and 5MPa for 1.0 hour to obtain a 40mm thick bamboo composite board. c. The bamboo composite board is cut into square bamboo strips with a specified module of 6×6mm by a wood slitting machine; the cut bamboo strips are fed into a bamboo stick forming machine and turned into round bamboo sticks with a diameter of 5.5 mm. d. Place the round bamboo sticks on the length-cutting machine and cut them into 180mm long bamboo stick segments; e. Sharpen both ends of the bamboo stick segment to a 60° angle, then cut it in half using a length-cutting machine to obtain the finished bamboo nail. The bamboo nail is 90mm long and 5.5mm in diameter.

[0039] f. As a control, 10 imported beech wood nails were randomly selected and tested for mechanical properties along with 10 bamboo nails. The test results are shown in Table 2.

[0040] Table 2 Comparison of physical and mechanical properties of beech wood nails and bamboo nails from Example 2 Note: The numbers in parentheses are the standard deviations of the test samples. Example 3 a. First, prepare the structural mixed resin by weighing 75 parts of low molecular weight phenolic resin, 6 parts of 4114 alkaline antifungal and preservative agent, 7 parts of ethanol, 6 parts of 4-bromo-1,8-naphthalenedicarboxylic anhydride, and 6 parts of 2-amino-1,3-propanediol. Add all components to a mixing tank and stir until homogeneous to obtain the mixed resin.

[0041] b. After impregnating bamboo fiber bundles with mixed resin for 10 seconds and drying them, the bundles are laid out in an oriented manner and then hot-pressed at 140°C and 4MPa for 1.2 hours to obtain a 40mm thick bamboo composite board. c. The bamboo composite board is cut into square bamboo strips with a specified module of 6×6mm by a wood slitting machine; the cut bamboo strips are fed into a bamboo stick forming machine and turned into round bamboo sticks with a diameter of 4.5 mm. d. Place the round bamboo sticks on the length-cutting machine and cut them into 150mm long bamboo stick segments; e. Sharpen both ends of the bamboo stick segment to a 45° angle, then cut it in the middle using a length-cutting machine to obtain the finished bamboo nail. The bamboo nail is 75mm long and 5mm in diameter.

[0042] f. As a control, 10 imported beech wood nails were randomly selected and tested for mechanical properties along with 10 bamboo nails. The test results are shown in Table 3.

[0043] Table 3 Comparison of physical and mechanical properties of beech wood nails and bamboo nails from Example 3 Note: The numbers in parentheses are the standard deviations of the test samples. Comparative Example 1 The difference between this comparative example and Example 1 is that in preparing the mixed resin for the structure, the composition consists of only 84 parts of low molecular weight phenolic resin and 3 parts of 4114 alkaline antifungal and preservative agent. All components are added to a mixing tank and stirred until homogeneous to obtain the mixed resin. Other steps are the same as in Example 1.

[0044] Comparative Example 2 The difference between this comparative example and Example 2 is that in preparing the mixed resin for the structure, the composition consists of only 80 parts of low molecular weight phenolic resin, 5 parts of 4114 alkaline antifungal and preservative agent, 3 parts of ethanol, and 6 parts of 4-bromo-1,8-naphthalenedicarboxylic anhydride. All components are added to a mixing tank and stirred until homogeneous to obtain the mixed resin. Other steps are the same as in Example 2.

[0045] The physical and mechanical properties of the bamboo nails obtained in Comparative Examples 1 and 2 are shown in Table 4 below. As can be seen from the table, the mechanical properties of the bamboo nails were significantly reduced because the structural adhesive formulation specific to this invention was not used. This is because only the adhesive effect of low molecular weight phenolic resin works on the bamboo fiber bundles; without a chain extender, the lignin in the bamboo is difficult to cross-link, and the bending and tensile strength of the bamboo cannot be fully utilized.

[0046] Table 4 Physical and mechanical properties of bamboo nails in Comparative Examples 1 and 2 The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of manufacturing a bamboo nail, characterized by, It comprises the following steps: S1, selecting mature bamboo or small-diameter bamboo, processing into bamboo strips through splitting and node removal; S2, processing the bamboo strips into bamboo fiber bundles or bamboo filaments through defibration; S3, drying the obtained bamboo fiber bundles or bamboo filaments; S4, dipping the dried bamboo fiber bundles or bamboo filaments into a mixed resin for structure, and then drying or airing; S5, uniformly laying the dried or aired bamboo fiber bundles or bamboo filaments into a blank, and then hot-pressing and curing to form a bamboo composite board; S6, cutting the bamboo composite board into square bamboo strips by a cutting machine; S7, forming the square bamboo strips into round bamboo rods by a forming machine; S8, processing the round bamboo rods to a fixed length and sharpening the ends to obtain bamboo nails.

2. The production method according to claim 1, characterized by, The drying in step S3 controls the water content to 6-12%.

3. The method of claim 1, wherein, The dipping time in step S4 is 5-300 s, and the drying or airing controls the water content to 8-12%.

4. The method of claim 1, wherein, The mixed resin for structure used in step S4 comprises the following components by weight: 70-90 parts of low molecular weight phenolic resin, 3-10 parts of 4114 alkaline antifungal preservative, 3-10 parts of ethanol, 5-10 parts of 4-bromo-1,8-naphthalene dicarboxylic anhydride, and 5-10 parts of 2-amino-1,3-propanediol. All the components are uniformly mixed to obtain the mixed resin for structure.

5. The preparation method according to claim 1, characterized in that, The process parameters of hot-pressing and curing in step S5 are: 120-155℃, 2-5 MPa pressure, hot-pressing for 0.5-3.0 min per mm of board thickness.

6. The method of claim 1, wherein, The step S8 specifically comprises the following steps: first, placing the round bamboo rod on a sizing machine to cut it to a length twice that of the bamboo nail, then sharpening the ends of the cut round bamboo rod, and then cutting the processed round bamboo rod in the middle by the sizing machine to obtain the bamboo nail.

7. A bamboo peg characterised in that, Prepared by the preparation method of any one of claims 1-6.

8. The bamboo nail according to claim 7, wherein, The length of the bamboo nail is 50-120 mm, the diameter is 4.0-10.0 mm, and the nail tip angle is 30°-60°.

9. The use of the bamboo nail of claim 7 or 8 in the connection of wood components or wood product parts.

10. Use according to claim 9, characterized in that, The bamboo nail is driven into the wood components or wood product parts by an F60 pneumatic nail gun.

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