Production method of environment-friendly flexible flattened bamboo veneer

Abstract

The invention discloses a production method of an environment-friendly flexible flattened bamboo veneer. The production method comprises the following steps: [1] sectioning raw bamboos in sections; (2) softening and shaping treatment; (3) slicing; [4] flattened bamboo veneer modification: dipping the flattened bamboo veneer prepared in the step [3] in a modification solution, and placing the flattened bamboo veneer in ultraviolet light with the wavelength of 365-395 nm and the power of 200 W / m < 2 > for treatment for 10-20 min, wherein the modification solution comprises 8-10 wt% of hydrogen peroxide, 2-3 wt% of sodium hydroxide and 0.15 wt% of aluminum chloride mixed aqueous solution; (5) the flattened bamboo veneers are rinsed and dried; and (6) carrying out flexible enhancement treatment, namely infiltrating polylactic acid / poly (butylene succinate) resin into fiber gaps of the modified flattened bamboo veneer at 105 DEG C by adopting a dipping or spraying mode, and then cooling and curing the modified flattened bamboo veneer dipped with the polylactic acid / poly (butylene succinate) resin under the pressure of 0.1-0.2 MPa, the mass ratio of the polylactic acid / poly (butylene succinate) resin to the modified flattened bamboo veneer is 5: 95. The flexibility of the bamboo veneer is greatly enhanced, and the application field of the bamboo veneer is widened.

Description

Technical Field

[0001] The invention relates to the technical field of bamboo material processing, in particular to a production method of an environmentally friendly flexible flattened bamboo veneer. Background Art

[0002] Flattened bamboo veneer is a sheet material made by cutting, splitting, removing the nodes from the bamboo tube, and then softening it at high temperature, flattening it without leaving any marks, and drying and shaping it. Its thickness is generally 1-10mm, and it is a way of processing and utilizing bamboo. "Replacing plastic with bamboo" is to process bamboo into products that can replace plastics in various ways in order to reduce plastic pollution and support sustainable development. In the process of practicing "replacing plastic with bamboo", flattened bamboo veneer is used to prepare thin plastic substitute products such as disposable dinner plates, saucers, fruit plates, water cups and packaging bags. Problems such as poor plasticity and insufficient water and mildew resistance of thin flattened bamboo veneer are faced. In addition, due to the strong rigidity, poor flexibility and lack of transverse cell organization of bamboo, the flattened bamboo veneer is prone to cracking and breakage, which hinders the flattened bamboo veneer from achieving the purpose of "replacing plastic with bamboo" in the above scenarios. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for producing an environmentally friendly flexible flattened bamboo veneer, thereby solving the problems of low thinness, poor lateral strength and overall toughness of the flattened bamboo veneer in the prior art.

[0004] The present invention adopts the following technical scheme: a method for producing an environmentally friendly flexible flattened bamboo veneer, which comprises the following steps:

[0005] [1] Cutting bamboo into sections: Cut 4-6 year old fresh bamboo with no obvious surface defects into bamboo tubes with a length of 1.0m-3.0m. After removing the inner and outer nodes, saw or cut the bamboo tube into 1-3 curved bamboo pieces along the radial direction;

[0006] [2] Softening and shaping treatment: The curved bamboo strips are softened by saturated steam or microwave heating at a temperature of 150°C-180°C for 5-10 minutes to destroy the lignin structure of the bamboo. After enhancing the plasticity, the softened curved bamboo strips are subjected to gradient roller pressing to gradually shape them into a concentric circle structure, and finally obtain a round curved bamboo strip with uniform curvature;

[0007] [3] Planing: According to the specifications of the flattened bamboo veneer, a precision planing tool is used to cut the shaped concentric arc bamboo slices to produce a flattened bamboo veneer with a thickness of 0.08mm-0.3mm;

[0008] [4] Modification of flattened bamboo veneer: immersing the flattened bamboo veneer obtained in step [3] in a modification solution and subjecting it to ultraviolet light treatment at a wavelength of 365nm-395nm and a power of 200W / rn2 for 10-20min, wherein the modification solution comprises a mixed aqueous solution of 8-10wt% hydrogen peroxide, 2-3wt% sodium hydroxide and 0.15wt% aluminum chloride;

[0009] [5] Rinse and dry the flattened bamboo veneer: rinse the modified flattened bamboo veneer after the treatment in step [4] in water until the pH is neutral, and then dry it in a suspended track transport mode or a mesh belt mode at a temperature of 60° C. to 110° C.;

[0010] [6] Flexibility enhancement treatment: The polylactic acid / polybutylene succinate resin is infiltrated into the fiber gaps of the modified flattened bamboo veneer at 105°C by dipping or spraying. The modified flattened bamboo veneer impregnated with the polylactic acid / polybutylene succinate resin is then cooled and solidified under a pressure of 0.1-0.2 MPa. The mass ratio of the polylactic acid / polybutylene succinate resin to the modified flattened bamboo veneer is 5:95.

[0011] As an improvement, the method further includes step [7] of flexible flattening bamboo veneer multilayer composite: the multilayer flexible bamboo veneer obtained in step [6] is subjected to one or more of fusion, splicing, lamination, winding, composite molding, and bending processing techniques under heating conditions to achieve diversified material morphology construction to meet the geometric structure requirements of different products.

[0012] As an improvement, in step [1], in the raw bamboo segmentation, a 5-year-old fresh raw bamboo with no obvious surface defects is cut into bamboo tubes with a length of 1.5 m. After removing the inner and outer nodes, the bamboo tube is radially sawed or split into three arc-shaped bamboo pieces.

[0013] As an improvement, in step [2], the softening and shaping treatment, the curved bamboo strips are placed at a constant temperature of 170° C. for 6 minutes for softening treatment.

[0014] As an improvement, in the planing step [3], the thickness of the flattened bamboo veneer obtained is 0.12 mm.

[0015] As an improvement, in step [4] of flattening the micro-bamboo veneer for modification, the flattened bamboo veneer is treated with ultraviolet light for 15 minutes, and the modified solution comprises a mixed aqueous solution of 8 wt % hydrogen peroxide, 2.5 wt % sodium hydroxide, and 0.15 wt % aluminum chloride.

[0016] As an improvement, in step [5], the flattened bamboo veneer is rinsed and dried at a drying temperature of 75°C.

[0017] As an improvement, in step [6], in the flexibility enhancement treatment, the modified flattened bamboo veneer impregnated with polylactic acid / polybutylene succinate resin is placed in a circulating oil-cooled flat plate press and cooled at a pressure of 0.1 MPa for 10 seconds.

[0018] The beneficial effects of the present invention are as follows: by modifying and flexibly enhancing the flattened bamboo veneer, the flexibility of the bamboo veneer is greatly enhanced, the application field of the bamboo veneer is broadened, and the demand of "replacing plastic with bamboo" in more scenarios is met. The ultraviolet light modification and polylactic acid / polybutylene succinate resin enhancement technology used in the process are both environmentally friendly treatment methods, which are in line with the sustainable development goal of "replacing plastic with bamboo". DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention are described in detail below.

[0020] Example 1

[0021] A method for producing an environmentally friendly flexible flattened bamboo veneer comprises the following steps:

[0022] [1] Cutting the original bamboo into sections:

[0023] Select 5-year-old fresh raw bamboo (such as moso bamboo) with no obvious surface defects and cut it into bamboo tubes with a length of 1.5m. Use mechanical sawing equipment to remove the inner and outer nodes of the bamboo tube, and then use a splitting machine to divide the bamboo tube into 3 arc-shaped bamboo pieces along the radial direction of the bamboo tube. The width of each arc-shaped bamboo piece is about one-third of the circumference of the bamboo tube, and the length is maintained at 1.5m. This process ensures that the basic shape of the bamboo is suitable for subsequent processing while maximizing material utilization.

[0024] [2] Softening and shaping treatment:

[0025] The arc-shaped bamboo slices obtained in step [1] are placed in a high-temperature and high-pressure cooking device and heated and softened by saturated steam or microwave. The device temperature is set to 170°C, the processing time is 6 minutes, and the steam or microwave pressure is controlled at 0.2MPa. Through the action of high-temperature steam or microwave, the lignin and hemicellulose structures in the bamboo material are partially destroyed, thereby enhancing the plasticity of the bamboo slices. Subsequently, the softened arc-shaped bamboo slices are sent to a variable-wheelbase spherical roller group device for gradient rolling. The roller group is composed of a plurality of spherical rollers with gradually decreasing diameters, and the roller spacing is gradually reduced from the initial 10mm to 2mm, and the rolling speed is 0.5m / min. Through gradient rolling, the arc-shaped bamboo slices are gradually unfolded and shaped into a concentric circle structure, and finally a round arc bamboo slice with uniform curvature is obtained.

[0026] [3] Slicing:

[0027] The round bamboo slices obtained in step [2] are placed on a precision planer and cut using a high-precision planer tool. The back angle of the tool is set to 20°, the cutting speed is 1.2 m / s, and the feed rate is 0.1 mm per time. By precisely controlling the cutting parameters, the round bamboo slices are processed into flattened bamboo veneers with a thickness of 0.12 mm. The resulting veneer is 300 mm wide and 1.5 m long, with a smooth surface and no obvious cracks. This step ensures that the veneer meets the thinning requirements while maintaining structural integrity.

[0028] [4] Modification of flattened bamboo veneer:

[0029] Prepare the modified solution, take 8wt% hydrogen peroxide (H 2 O 2 ), 2.5wt% sodium hydroxide (NaOH) and 0.15wt% aluminum chloride (AlCl 3 ) in deionized water and stirred thoroughly until uniform. The flattened bamboo veneer obtained in step [3] is completely immersed in the modified solution, the solution temperature is maintained at 40°C, and the immersion time is 30 minutes. Subsequently, the bamboo veneer after immersion is taken out and placed under an ultraviolet light treatment device, and irradiated with ultraviolet light with a wavelength of 365nm and a power of 200W / m 2 The treatment time is 15 minutes. The ultraviolet light combined with the modified solution opens up the tiny gaps between the fibers of the flattened bamboo veneer and enhances its reactivity with the subsequent polylactic acid / polybutylene succinate resin.

[0030] [5] Flatten the bamboo veneer, rinse and dry:

[0031] Place the flattened bamboo veneer modified in step [4] in a running water rinsing tank and rinse repeatedly with deionized water until the pH value of the veneer surface reaches neutral (pH 6.8-7.2). After rinsing, send the bamboo veneer to a mesh belt drying device, set the drying temperature to 75°C, the mesh belt running speed to 0.3m / min, and the hot air speed to 5m / s. Dry until the veneer moisture content is less than 10% (about 8%) to obtain a dry modified flattened bamboo veneer. This step ensures that the veneer surface is clean and has an appropriate moisture content, laying the foundation for subsequent flexibility enhancement treatment.

[0032] [6]Flexibility enhancement treatment

[0033] The melt impregnation method is used for flexibility enhancement treatment. The polylactic acid (PLA) / polybutylene succinate (PBS) resin (a mixture with a mass ratio of 1:1) is heated to 105°C to completely melt it into a liquid state. The modified flattened bamboo veneer obtained in step [5] is immersed in the molten resin for 5 minutes to ensure that the resin fully penetrates the fiber gaps of the bamboo veneer. The mass ratio of polylactic acid / polybutylene succinate resin to modified flattened bamboo veneer is controlled to be 5:95. After the impregnation is completed, the bamboo veneer is taken out and immediately placed in a circulating oil-cooled flat plate press, cooled and solidified at a pressure of 0.1MPa, and the cooling time is 10s. After cooling, the resin forms a uniform flexible reinforcement layer inside the bamboo veneer, which significantly improves the toughness and lateral strength of the veneer.

[0034] [7] Flexible flattened bamboo veneer multi-layer composite:

[0035] The flexible flattened bamboo veneer obtained in step [6] is subjected to multi-layer composite processing. Three pieces of flexible bamboo veneer are taken and stacked in an offset manner along the fiber direction (the offset angle is 30°), and hot pressed at 110°C and 0.15MPa for 5 minutes to allow the veneers to be tightly bonded through the melt bonding of the polylactic acid / polybutylene succinate resin. The thickness of the composite material is about 0.35mm, and it can be cut into different sizes (such as 500mm×500mm) according to needs, or made into a tubular structure (such as a bamboo straw with an inner diameter of 20mm) through a winding process. This step realizes the construction of a diversified form of veneer to meet the geometric requirements of different plastic products.

[0036] Implementation effect verification:

[0037] After testing, the flexible flattened bamboo veneer prepared in Example 1 has the following properties:

[0038] Longitudinal tensile strength: 45MPa, higher than traditional flattened bamboo veneer (about 30MPa).

[0039] Transverse tensile strength: 4.5MPa, about 50% higher than traditional single board.

[0040] Flexibility: The minimum bending diameter is 20mm without cracks.

[0041] Water resistance: After immersion in water for 24 hours, the water absorption rate is less than 15%, and there is no sign of mildew on the surface.

[0042] The above embodiment prepares a flexible flattened bamboo veneer with a thickness of only 0.12 mm through the steps of segmenting, softening and shaping, slicing, modification and flexibility enhancement of the original bamboo, overcoming the defects of low thinness, insufficient lateral strength and poor toughness of the traditional flattened bamboo veneer. The ultraviolet light modification and polylactic acid / polybutylene succinate resin enhancement technology used in the process are both environmentally friendly treatment methods, which are in line with the sustainable development goal of "replacing plastic with bamboo". According to the above description, those skilled in the art can directly reproduce the invention according to the parameters and process flow to prepare a flexible flattened bamboo veneer with excellent performance.

Claims

1. A method for producing an environmentally friendly flexible flattened bamboo veneer, characterized in that: It includes the following steps: [1] Cutting bamboo into sections: Cut 4-6 year old fresh bamboo with no obvious surface defects into bamboo tubes with a length of 1.0m-3.0m. After removing the inner and outer nodes, saw or cut the bamboo tube into 1-3 curved bamboo pieces along the radial direction; [2] Softening and shaping treatment: The curved bamboo strips are softened by saturated steam or microwave heating at a temperature of 150°C-180°C for 5-10 minutes to destroy the lignin structure of the bamboo. After enhancing the plasticity, the softened curved bamboo strips are subjected to gradient roller pressing to gradually shape them into a concentric circle structure, and finally obtain a round curved bamboo strip with uniform curvature; [3] Planing: According to the specifications of the flattened bamboo veneer, a precision planing tool is used to cut the shaped concentric arc bamboo slices to produce a flattened bamboo veneer with a thickness of 0.08mm-0.3mm; [4] Modification of flattened bamboo veneer: immersing the flattened bamboo veneer obtained in step [3] in a modification solution and subjecting it to ultraviolet light treatment at a wavelength of 365nm-395nm and a power of 200W / rn2 for 10-20min, wherein the modification solution comprises a mixed aqueous solution of 8-10wt% hydrogen peroxide, 2-3wt% sodium hydroxide and 0.15wt% aluminum chloride; [5] Rinse and dry the flattened bamboo veneer: rinse the modified flattened bamboo veneer after the treatment in step [4] in water until the pH is neutral, and then dry it in a suspended track transport mode or a mesh belt mode at a temperature of 60° C. to 110° C.; [6] Flexibility enhancement treatment: The polylactic acid / polybutylene succinate resin is infiltrated into the fiber gaps of the modified flattened bamboo veneer at 105°C by dipping or spraying. The modified flattened bamboo veneer impregnated with the polylactic acid / polybutylene succinate resin is then cooled and solidified under a pressure of 0.1-0.2 MPa. The mass ratio of the polylactic acid / polybutylene succinate resin to the modified flattened bamboo veneer is 5:

95.

2. The method for producing an environmentally friendly flexible flattened bamboo veneer according to claim 1, characterized in that: The method also includes step [7] of flexible flattening bamboo veneer multilayer composite: the multilayer flexible bamboo veneer obtained in step [6] is subjected to one or more of fusion, splicing, lamination, winding, composite molding, and bending processing techniques under heating conditions to achieve diversified material morphology construction to meet the geometric structure requirements of different products.

3. The method for producing an environmentally friendly flexible flattened bamboo veneer according to claim 1 or 2, characterized in that: In the step [1] of cutting the raw bamboo into sections, a 5-year-old fresh raw bamboo with no obvious surface defects is cut into bamboo tubes with a length of 1.5 m, and after removing the inner and outer nodes, the bamboo tubes are sawed or cut into three arc-shaped bamboo pieces along the radial direction.

4. The method for producing an environmentally friendly flexible flattened bamboo veneer according to claim 1 or 2, characterized in that: In the softening and shaping process of step [2], the curved bamboo strips are placed under a constant temperature of 170° C. and softened for 6 minutes.

5. The method for producing an environmentally friendly flexible flattened bamboo veneer according to claim 1 or 2, characterized in that: In the planing step [3], the flattened bamboo veneer obtained has a thickness of 0.12 mm.

6. The method for producing an environmentally friendly flexible flattened bamboo veneer according to claim 1 or 2, characterized in that: In the step [4] of flattening the micro-bamboo veneer for modification, the flattened bamboo veneer is treated with ultraviolet light for 15 minutes, and the modified solution comprises a mixed aqueous solution of 8 wt % hydrogen peroxide, 2.5 wt % sodium hydroxide, and 0.15 wt % aluminum chloride.

7. The method for producing an environmentally friendly flexible flattened bamboo veneer according to claim 1 or 2, characterized in that: In the step [5] of flattening the bamboo veneer, rinsing and drying, the drying temperature is 75°C.

8. The method for producing an environmentally friendly flexible flattened bamboo veneer according to claim 1 or 2, characterized in that: In the flexibility enhancement treatment of step [6], the modified flattened bamboo veneer impregnated with polylactic acid / polybutylene succinate resin is placed in a circulating oil-cooled flat plate press and cooled at a pressure of 0.1 MPa for 10 seconds.