A method for improving the gluing performance of heat-treated bamboo

Abstract

The present invention discloses a method for improving the gluing performance of heat-treated bamboo, belonging to the technical field of bamboo processing, and comprising the following steps: S1, fumigation treatment; S2, ultrasonic-electric field alternating treatment; S3, heat treatment; S4, spraying-drying cycle treatment. The present application provides a method for improving the gluing performance of heat-treated bamboo. After being treated by the method of the present application, the equilibrium contact angle of the bamboo becomes smaller, and the surface wettability is significantly improved, which is beneficial to the penetration and spreading of adhesives such as phenolic resin adhesives on its surface, thereby promoting the improvement of the gluing strength. Moreover, the method for improving the gluing performance of heat-treated bamboo in the present application is a whole, and there is a synergistic effect between each step. After the bamboo is treated by the method of the present application, the gluing performance is significantly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of bamboo strip processing, and particularly relates to a method for improving the gluing performance of heat-treated bamboo. Background Art

[0002] With the development of the wood processing industry, the contradiction between the supply and demand of wood has become increasingly fierce. One of the important measures to alleviate this contradiction is to use bamboo instead of wood, and great progress has also been made in the industrial utilization of bamboo. In the early 1990s of the 20th century, the industrial utilization of bamboo in China just started. After nearly thirty years of research and development, the development of China's bamboo industry has gone through the following stages, including high-yielding of moso bamboo and the research and production of various bamboo products.

[0003] Bamboo has a small diameter, a thin bamboo wall, a hollow interior, and a large taper. Its structural composition and chemical composition are quite different from those of wood. Bamboo has the following characteristics: First, it has a short growth cycle and high yield, and is an excellent renewable resource. Second, bamboo has a soft color, clear texture, smooth feel, and elasticity, and has good decorative effects. Third, bamboo is light in weight, good in rigidity, and high in strength, so the strength of bamboo products is also higher than that of general wood products. It can be used as structural materials, improving the economic and environmental benefits of enterprises, and bamboo can be used to replace wood to manufacture products. Fourth, because bamboo has straight texture and simple color, it is easy to be bleached, dyed, carbonized, etc., and can be made into bamboo laminated lumber, bamboo flooring, etc., with broad application prospects. Fifth, bamboo has the characteristics of high toughness and good splitting property, and is easy to split and weave, so various bamboo products can be made through simple processing. Sixth, it has good processability and can be processed by turning, milling, carving and other processes. Seventh, due to the nutrients contained in bamboo, bamboo is prone to mildew, poor in corrosion resistance and insect resistance, and needs to be treated to improve the durability of bamboo; moreover, in the process of bamboo product processing, the labor productivity is low, the utilization rate is low, and the production cost is relatively high.

[0004] The high-temperature heat treatment technology of bamboo is a physical modification technology that places bamboo materials in an environment of high temperature, anaerobic or low oxygen content for short-term pyrolysis treatment, which can effectively improve the biological durability and dimensional stability of bamboo, and has become an effective means for the high-value utilization of bamboo. However, there are prominent problems such as poor permeability and gluing performance of the adhesive resin in bamboo units during the processing and use of heat-modified bamboo. Although there are currently special improvement methods for the gluing performance of heat-treated bamboo, the effects are generally average, seriously restricting the popularization and application of heat-treated bamboo. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for improving the gluing performance of heat-treated bamboo in view of the existing problems.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for improving the gluing performance of heat-treated bamboo, comprising the following steps:

[0008] S1. Fumigation treatment:

[0009] After making bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment, and take them out for standby after completion;

[0010] S2. Ultrasonic-electric field alternating treatment:

[0011] Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then carry out ultrasonic-electric field alternating treatment, and take them out for standby after completion;

[0012] S3. Heat treatment:

[0013] Carry out heat treatment on the bamboo strips treated in step S2 to obtain heat-treated bamboo strips for standby;

[0014] S4. Spray coating-drying cycle treatment:

[0015] Carry out cycle treatment of spray coating and drying treatment of treatment liquid B on the heat-treated bamboo strips. One spray coating of treatment liquid B and one drying treatment are one cycle.

[0016] Further, the fumigation treatment in step S1 is steam fumigation, and the fumigation treatment time is 8-10h.

[0017] Further, the components and corresponding weight percentages in the treatment liquid A in step S2 are: ammonium nitrate 3-5%, ferric sulfate 1-3%, sodium dodecylbenzenesulfonate 7-10%, fatty acid glyceride 5-9%, calcium silicate 2-4%, and the balance is water.

[0018] Further, the ultrasonic-electric field alternating treatment in step S2 is specifically: first carry out one ultrasonic treatment, then carry out electric field treatment, and finally carry out secondary ultrasonic treatment.

[0019] Further, when carrying out ultrasonic treatment, insert the ultrasonic probe 2-3 cm below the liquid level of the treatment liquid, the frequency of ultrasonic waves during treatment is controlled at 30-50 kHz, the time of one ultrasonic treatment is 1-2 h, and the time of secondary ultrasonic treatment is 30-40 min.

[0020] Further, when carrying out electric field treatment, turn on the power supply, control the voltage at 60-100 V, and the electric field treatment time is 8-12 min.

[0021] Further, the components and their corresponding weight percentages in the treatment liquid B described in step S4 are: fulvic acid 3-6%, lanthanum nitrate 5-9%, decanoyl acetaldehyde 0.7-0.9%, α-bisabolol 1-3%, nano zinc oxide 5-10%, absolute ethanol 20-30%, and the balance is pure water.

[0022] Further, the drying treatment described in step S4 is a low-temperature vacuum drying treatment, the temperature is 30-40 °C, and each time it is dried until the moisture content is 8-10%.

[0023] Further, the cycle treatment described in step S4 is carried out for a total of 4-6 cycles.

[0024] By adopting the above technical solutions, the bamboo strips are successively subjected to fumigation treatment, ultrasonic-electric field alternating treatment in treatment liquid A, heat treatment, and treatment liquid B spraying-low-temperature vacuum drying cycle treatment, which makes the gaps on the surface of the bamboo material larger, generates more free radicals, and can form unevenness and grooves on the surface of the bamboo material, thus facilitating the penetration and spreading of the adhesive, so the equilibrium contact angle becomes smaller and the surface wettability is numbered, thereby being able to form more glue nails and promoting the improvement of the bonding strength. In addition, the technical parameters of each treatment step in this application are obtained on the basis of a large number of experiments, and each technical parameter needs to be strictly controlled. Otherwise, it is extremely easy to cause damage to the surface fibers of the bamboo material, thereby reducing the shear strength of the bamboo material surface layer and thus affecting the improvement of its bonding performance.

[0025] The present invention has the following advantages compared with the prior art:

[0026] This application provides a method for improving the bonding performance of heat-treated bamboo. After being treated by the method of this application, the equilibrium contact angle of the bamboo material becomes smaller, and the surface wettability is significantly improved, which is beneficial to the penetration and spreading of adhesives such as phenolic resin adhesives on its surface, thus promoting the improvement of the bonding strength. And the method for improving the bonding performance of heat-treated bamboo in this application is a whole, and each step has a synergistic effect. After the bamboo material is treated by the method of this application, the bonding performance has been significantly improved. Description of the Drawings

[0027] Figure 1 It is a comparison chart of the equilibrium contact angle test results of each group of bamboo materials in the specific embodiment part of this application;

[0028] Figure 2 It is a comparison chart of the bonding strength test results of each group of bamboo materials in the specific embodiment part of this application. Specific Embodiments

[0029] In order to further explain the present invention, the following specific embodiments are described below. Example 1

[0030] A method for improving the gluing performance of heat-treated bamboo, comprising the following steps:

[0031] S1. Fumigation treatment:

[0032] After making the bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation. After 8 hours of fumigation treatment, take them out and set aside.

[0033] S2. Ultrasonic - electric field alternating treatment:

[0034] Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then carry out ultrasonic - electric field alternating treatment. Specifically, first carry out ultrasonic treatment once, then carry out electric field treatment, and finally carry out ultrasonic treatment twice. After completion, take them out and set aside.

[0035] The components and their corresponding weight percentages in treatment liquid A are: ammonium nitrate 3%, ferric sulfate 1%, sodium dodecylbenzenesulfonate 7%, fatty acid glyceride 5%, calcium silicate 2%, and the balance is water.

[0036] When carrying out ultrasonic treatment, insert the ultrasonic probe 2 cm below the liquid level of the treatment liquid. During the treatment, the frequency of the ultrasonic wave is controlled at 30 kHz. The time of the first ultrasonic treatment is 1 hour, and the time of the second ultrasonic treatment is 30 minutes.

[0037] When carrying out electric field treatment, turn on the power supply, control the voltage at 60 V, and the time of electric field treatment is 8 minutes.

[0038] S3. Heat treatment:

[0039] Carry out heat treatment on the bamboo strips treated in step S2 to obtain heat-treated bamboo strips for standby.

[0040] S4. Spraying - drying cycle treatment:

[0041] Carry out cycle treatment of spraying treatment liquid B and drying treatment on the heat-treated bamboo strips. One spraying of treatment liquid B and one drying treatment is one cycle, and a total of 4 cycles are treated.

[0042] The components and their corresponding weight percentages in treatment liquid B are: fulvic acid 3%, lanthanum nitrate 5%, decanoyl acetaldehyde 0.7%, α - bisabolol 1%, nano zinc oxide 5%, absolute ethanol 20%, and the balance is pure water.

[0043] The drying treatment is low-temperature vacuum drying treatment, the temperature is 30 °C, and each time it is dried to a moisture content of 8%. Example 2

[0044] A method for improving the gluing performance of heat-treated bamboo, comprising the following steps:

[0045] S1. Fumigation treatment:

[0046] After making bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation. After 9 hours of fumigation treatment, take them out and set aside for later use;

[0047] S2. Ultrasonic - electric field alternating treatment:

[0048] Immerse the fumigated bamboo strips in treatment liquid A, and then conduct ultrasonic - electric field alternating treatment. Specifically, first conduct ultrasonic treatment once, then conduct electric field treatment, and finally conduct ultrasonic treatment twice. After completion, take them out and set aside for later use;

[0049] The components and their corresponding weight percentages in treatment liquid A are: ammonium nitrate 4%, ferric sulfate 2%, sodium dodecylbenzenesulfonate 8.5%, fatty acid glyceride 7%, calcium silicate 3%, and the balance is water;

[0050] When conducting ultrasonic treatment, insert the ultrasonic probe 2.5 cm below the liquid level of the treatment liquid. During treatment, the frequency of ultrasonic waves is controlled at 40 kHz. The time for the first ultrasonic treatment is 1.5 hours, and the time for the second ultrasonic treatment is 35 minutes;

[0051] When conducting electric field treatment, turn on the power supply, control the voltage at 80 V, and the time for electric field treatment is 10 minutes;

[0052] S3. Heat treatment:

[0053] Conduct heat treatment on the bamboo strips treated in step S2 to obtain heat - treated bamboo strips for later use;

[0054] S4. Spray - drying cycle treatment:

[0055] Conduct cycle treatment of spraying treatment liquid B and drying on the heat - treated bamboo strips. Spraying treatment liquid B once and drying once is one cycle, and a total of 5 cycles are processed;

[0056] The components and their corresponding weight percentages in treatment liquid B are: fulvic acid 4.5%, lanthanum nitrate 7%, decanoyl acetaldehyde 0.8%, α - bisabolol 2%, nano - zinc oxide 7.5%, absolute ethanol 25%, and the balance is pure water;

[0057] The drying treatment is low - temperature vacuum drying treatment, with the temperature at 35°C, and each time it is dried until the moisture content is 9%. Example 3

[0058] A method for improving the gluing performance of heat - treated bamboo, comprising the following steps:

[0059] S1. Fumigation treatment:

[0060] After making bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation. After 10 hours of fumigation treatment, take them out and reserve for use.

[0061] S2. Ultrasonic - electric field alternating treatment:

[0062] Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then conduct ultrasonic - electric field alternating treatment. Specifically, first conduct ultrasonic treatment once, then conduct electric field treatment, and finally conduct ultrasonic treatment twice. After completion, take them out and reserve for use.

[0063] The components and corresponding weight percentages in treatment liquid A are: ammonium nitrate 5%, ferric sulfate 3%, sodium dodecylbenzenesulfonate 10%, fatty acid glyceride 9%, calcium silicate 4%, and the balance is water.

[0064] When conducting ultrasonic treatment, insert the ultrasonic probe 3 cm below the liquid level of the treatment liquid. During treatment, the frequency of ultrasonic waves is controlled at 50 kHz. The time of the first ultrasonic treatment is 2 hours, and the time of the second ultrasonic treatment is 40 minutes.

[0065] When conducting electric field treatment, turn on the power supply, control the voltage at 100 V, and the time of electric field treatment is 12 minutes.

[0066] S3. Heat treatment:

[0067] Conduct heat treatment on the bamboo strips treated in step S2 to obtain heat - treated bamboo strips for reserve.

[0068] S4. Spray - drying cycle treatment:

[0069] Conduct cycle treatment of spraying treatment liquid B and drying on the heat - treated bamboo strips. One spray of treatment liquid B and one drying is one cycle, and a total of 6 cycles are processed.

[0070] The components and corresponding weight percentages in treatment liquid B are: fulvic acid 6%, lanthanum nitrate 9%, decanoyl acetaldehyde 0.9%, α - bisabolol 3%, nano - zinc oxide 10%, absolute ethanol 30%, and the balance is pure water.

[0071] The drying treatment is low - temperature vacuum drying treatment, with a temperature of 40 °C, and each time it is dried until the moisture content is 10%.

[0072] Comparative example 1

[0073] A method for improving the gluing performance of heat - treated bamboo, including the following steps:

[0074] S1. Ultrasonic - electric field alternating treatment:

[0075] After making bamboo strips from bamboo lumber, immerse them in treatment liquid A, and then conduct ultrasonic-electric field alternating treatment. Specifically, first conduct ultrasonic treatment once, then conduct electric field treatment, and finally conduct ultrasonic treatment twice. After completion, take them out and set aside for later use;

[0076] The components and their corresponding weight percentages in treatment liquid A are: ammonium nitrate 4%, ferric sulfate 2%, sodium dodecylbenzenesulfonate 8.5%, fatty acid glyceride 7%, calcium silicate 3%, and the balance is water;

[0077] When conducting ultrasonic treatment, insert the ultrasonic probe 2.5 cm below the liquid level of the treatment liquid. During treatment, control the frequency of ultrasonic waves at 40 kHz. The time for the first ultrasonic treatment is 1.5 h, and the time for the second ultrasonic treatment is 35 min;

[0078] When conducting electric field treatment, turn on the power supply, control the voltage at 80 V, and the time for electric field treatment is 10 min;

[0079] S2. Heat treatment:

[0080] Conduct heat treatment on the bamboo strips treated in step S1 to obtain heat-treated bamboo strips for later use;

[0081] S3. Spray-coating - drying cycle treatment:

[0082] Conduct cycle treatment of spray-coating treatment liquid B and drying treatment on the heat-treated bamboo strips. One spray-coating of treatment liquid B and one drying treatment are one cycle, and a total of 5 cycles are processed;

[0083] The components and their corresponding weight percentages in treatment liquid B are: fulvic acid 4.5%, lanthanum nitrate 7%, decanoyl acetaldehyde 0.8%, α - bisabolol 2%, nano-zinc oxide 7.5%, absolute ethanol 25%, and the balance is pure water;

[0084] The drying treatment is low-temperature vacuum drying treatment, with the temperature at 35 °C, and each time it is dried until the moisture content is 9%.

[0085] Comparative Example 2

[0086] A method for improving the gluing performance of heat-treated bamboo, comprising the following steps:

[0087] S1. Fumigation treatment:

[0088] After making bamboo strips from bamboo lumber, place them in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation. After 9 h of fumigation treatment, take them out and set aside for later use;

[0089] S2. Ultrasonic - electric field treatment:

[0090] Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then perform ultrasonic-electric field treatment. Specifically, first perform ultrasonic treatment and then perform electric field treatment. After completion, take them out for standby;

[0091] The components and corresponding weight percentages in treatment liquid A are: ammonium nitrate 4%, ferric sulfate 2%, sodium dodecylbenzenesulfonate 8.5%, fatty acid glyceride 7%, calcium silicate 3%, and the balance is water;

[0092] When performing ultrasonic treatment, insert the ultrasonic probe 2.5 cm below the liquid level of the treatment liquid. During treatment, the frequency of the ultrasonic wave is controlled at 40 kHz, and the time of ultrasonic treatment is 1.5 h;

[0093] When performing electric field treatment, turn on the power supply, control the voltage at 80 V, and the time of electric field treatment is 10 min;

[0094] S3. Heat treatment:

[0095] Perform heat treatment on the bamboo strips treated in step S2 to obtain heat-treated bamboo strips for standby;

[0096] S4. Spray coating-drying cycle treatment:

[0097] Perform cycle treatment of spray coating and drying treatment of treatment liquid B on the heat-treated bamboo strips. One spray coating of treatment liquid B and one drying treatment is one cycle, and a total of 5 cycles are treated;

[0098] The components and corresponding weight percentages in treatment liquid B are: fulvic acid 4.5%, lanthanum nitrate 7%, decanoyl acetaldehyde 0.8%, α-bisabolol 2%, nano-zinc oxide 7.5%, absolute ethanol 25%, and the balance is pure water;

[0099] The drying treatment is low-temperature vacuum drying treatment, the temperature is 35 °C, and each time it is dried to a moisture content of 9%.

[0100] Comparative example 3

[0101] A method for improving the gluing performance of heat-treated bamboo, including the following steps:

[0102] S1. Fumigation treatment:

[0103] After making the bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation. After 9 h of fumigation treatment, take them out for standby;

[0104] S2. Electric field treatment:

[0105] Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then perform electric field treatment. After completion, take them out for standby;

[0106] The components and their corresponding weight percentages in treatment liquid A are as follows: ammonium nitrate 4%, ferric sulfate 2%, sodium dodecylbenzenesulfonate 8.5%, glycerol fatty acid ester 7%, calcium silicate 3%, and the balance is water;

[0107] When performing the electric field treatment, turn on the power supply, control the voltage to 80V, and the time of the electric field treatment is 10 minutes;

[0108] S3. Heat treatment:

[0109] Perform heat treatment on the bamboo strips treated in step S2 to obtain heat-treated bamboo strips for standby;

[0110] S4. Spraying - drying cycle treatment:

[0111] Perform a cycle treatment of spraying treatment liquid B and drying treatment on the heat-treated bamboo strips. One spraying of treatment liquid B and one drying treatment is one cycle, and a total of 5 cycles are processed;

[0112] The components and their corresponding weight percentages in treatment liquid B are as follows: fulvic acid 4.5%, lanthanum nitrate 7%, decanoyl acetaldehyde 0.8%, α - bisabolol 2%, nano zinc oxide 7.5%, absolute ethanol 25%, and the balance is pure water;

[0113] The drying treatment is a low-temperature vacuum drying treatment, the temperature is 35°C, and each time it is dried until the moisture content is 9%.

[0114] Comparative example 4

[0115] A method for improving the gluing performance of heat-treated bamboo, comprising the following steps:

[0116] S1. Fumigation treatment:

[0117] After making the bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation, and after 9 hours of fumigation treatment, take them out for standby;

[0118] S2. Ultrasonic treatment:

[0119] Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then perform ultrasonic treatment. After completion, take them out for standby;

[0120] The components and their corresponding weight percentages in treatment liquid A are as follows: ammonium nitrate 4%, ferric sulfate 2%, sodium dodecylbenzenesulfonate 8.5%, glycerol fatty acid ester 7%, calcium silicate 3%, and the balance is water;

[0121] When performing ultrasonic treatment, insert the ultrasonic probe 2.5 cm below the liquid level of the treatment liquid. During the treatment, control the frequency of the ultrasonic wave to 40 kHz, and the treatment time is 125 minutes;

[0122] When performing the electric field treatment, turn on the power supply, control the voltage to 80V, and the time for the electric field treatment is 10 minutes;

[0123] S3. Heat treatment:

[0124] Perform heat treatment on the bamboo strips processed in step S2 to obtain heat-treated bamboo strips for standby;

[0125] S4. Spray coating - drying cycle treatment:

[0126] Perform a cycle treatment of spray coating with treatment liquid B and drying on the heat-treated bamboo strips. One spray coating with treatment liquid B and one drying treatment is one cycle, and a total of 5 cycles are processed;

[0127] The components and corresponding weight percentages in treatment liquid B are: fulvic acid 4.5%, lanthanum nitrate 7%, decanoyl acetaldehyde 0.8%, α - bisabolol 2%, nano - zinc oxide 7.5%, anhydrous ethanol 25%, and the balance is pure water;

[0128] The drying treatment is a low - temperature vacuum drying treatment, with the temperature being 35°C, and each time it is dried until the moisture content is 9%.

[0129] Comparative Example 5

[0130] A method for improving the gluing performance of heat - treated bamboo, comprising the following steps:

[0131] S1. Fumigation treatment:

[0132] After making bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation, and after 9 hours of fumigation treatment, take them out for standby;

[0133] S2. Ultrasonic - electric field alternating treatment:

[0134] Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then perform ultrasonic - electric field alternating treatment. Specifically, first perform one ultrasonic treatment, then perform electric field treatment, and finally perform a second ultrasonic treatment. After completion, take them out for standby;

[0135] The components and corresponding weight percentages in treatment liquid A are: ammonium nitrate 4%, ferric sulfate 2%, sodium dodecylbenzenesulfonate 8.5%, fatty acid glyceride 7%, calcium silicate 3%, and the balance is water;

[0136] When performing ultrasonic treatment, insert the ultrasonic probe 2.5 cm below the liquid level of the treatment liquid. During the treatment, control the frequency of the ultrasonic wave to 40 kHz. The time for the first ultrasonic treatment is 1.5 hours, and the time for the second ultrasonic treatment is 35 minutes;

[0137] When performing the electric field treatment, turn on the power supply, control the voltage to 80V, and the time for the electric field treatment is 10 minutes;

[0138] S3. Heat treatment:

[0139] The bamboo strips processed in step S2 are subjected to heat treatment to obtain heat-treated bamboo strips for standby;

[0140] S4. Drying treatment:

[0141] The heat-treated bamboo strips are subjected to drying treatment, and the drying treatment is low-temperature vacuum drying treatment at a temperature of 35°C until the moisture content reaches 9% each time.

[0142] Comparative Example 6

[0143] A method for improving the gluing performance of heat-treated bamboo, comprising the following steps:

[0144] S1. Fumigation treatment:

[0145] After the bamboo is made into bamboo strips, it is placed in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation, and it is taken out for standby after 9 hours of fumigation treatment;

[0146] S2. Ultrasonic-electric field alternating treatment:

[0147] The bamboo strips after fumigation treatment are immersed in treatment liquid A, and then ultrasonic-electric field alternating treatment is carried out. Specifically, first, ultrasonic treatment is carried out once, then electric field treatment is carried out, and finally, ultrasonic treatment is carried out twice. After completion, it is taken out for standby;

[0148] The components and corresponding weight percentages in treatment liquid A are: ammonium nitrate 4%, ferric sulfate 2%, sodium dodecylbenzenesulfonate 8.5%, fatty acid glyceride 7%, calcium silicate 3%, and the balance is water;

[0149] When carrying out ultrasonic treatment, the ultrasonic probe is extended 2.5 cm below the liquid level of the treatment liquid. During the treatment, the frequency of the ultrasonic wave is controlled at 40 kHz. The time of the first ultrasonic treatment is 1.5 hours, and the time of the second ultrasonic treatment is 35 minutes;

[0150] When carrying out electric field treatment, the power supply is turned on, the voltage is controlled at 80 V, and the time of electric field treatment is 10 minutes;

[0151] S3. Heat treatment:

[0152] The bamboo strips processed in step S2 are subjected to heat treatment to obtain heat-treated bamboo strips for standby;

[0153] S4. Spray-drying cycle treatment:

[0154] The heat-treated bamboo strips are subjected to a cycle treatment of spraying treatment liquid B and drying treatment. Spraying treatment liquid B once and drying treatment once is one cycle, and a total of 1 cycle is processed;

[0155] The components and their corresponding weight percentages in treatment liquid B are as follows: fulvic acid 4.5%, lanthanum nitrate 7%, decanoyl acetaldehyde 0.8%, α-bisabolol 2%, nano-zinc oxide 7.5%, absolute ethanol 25%, and the balance is pure water;

[0156] The drying treatment is low-temperature vacuum drying treatment, the temperature is 35 °C, and each time it is dried until the moisture content is 9%.

[0157] Comparative Example 8

[0158] A method for improving the gluing performance of heat-treated bamboo, comprising the following steps:

[0159] S1. Fumigation treatment:

[0160] After making the bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment. The fumigation treatment is steam fumigation. After 9 hours of fumigation treatment, take them out and set aside;

[0161] S2. Ultrasonic-electric field alternating treatment:

[0162] Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then carry out ultrasonic-electric field alternating treatment. Specifically, first carry out ultrasonic treatment once, then carry out electric field treatment, and finally carry out ultrasonic treatment twice. After completion, take them out and set aside;

[0163] The components and their corresponding weight percentages in treatment liquid A are as follows: ammonium nitrate 4%, ferric sulfate 2%, sodium dodecylbenzenesulfonate 8.5%, fatty acid glyceride 7%, calcium silicate 3%, and the balance is water;

[0164] When carrying out ultrasonic treatment, insert the ultrasonic probe 2.5 cm below the liquid level of the treatment liquid. During the treatment, the frequency of the ultrasonic wave is controlled at 40 kHz. The time of the first ultrasonic treatment is 1.5 hours, and the time of the second ultrasonic treatment is 35 minutes;

[0165] When carrying out electric field treatment, turn on the power supply, control the voltage at 80 V, and the time of electric field treatment is 10 minutes;

[0166] S3. Heat treatment:

[0167] Carry out heat treatment on the bamboo strips treated in step S2 to obtain heat-treated bamboo strips for standby;

[0168] S4. Spray-coating-drying cycle treatment:

[0169] Carry out a cycle treatment of pure water spray-coating and drying treatment on the heat-treated bamboo strips. Spraying treatment liquid B once and drying treatment once is one cycle, and a total of 5 cycles are treated;

[0170] The drying treatment is low-temperature vacuum drying treatment, the temperature is 35 °C, and each time it is dried until the moisture content is 9%.

[0171] Control group

[0172] A method for improving the gluing performance of heat-treated bamboo, with the application number: 2022112521273, is disclosed.

[0173] To compare the technical effects of this application, bamboo materials of the same batch with the same texture and physical and chemical properties were selected for experiments. After processing the bamboo into bamboo strips, they were randomly divided into 9 groups of equal quality and quantity, namely Example 2, Comparative Examples 1-7, and the control group. Then, the bamboo strips of each group were processed according to the methods of each group, and performance tests were carried out after completion.

[0174] 1. Contact angle measurement

[0175] Using a static drop contact angle / interface tension measuring instrument, the change in the contact angle θ (°) of the phenolic resin adhesive on the tangential section of the bamboo strip was measured. Starting from the moment the test liquid was dropped onto the tangential section of the moso bamboo, the contact angle θ was measured every certain time interval (interval time: UF, 10 s; RF, 20 s). A set of θ-t curves was obtained for each specimen, and an exponential decay function was used for curve fitting to obtain the equilibrium contact angle θ0.

[0176] The test results are as Figure 1 shown.

[0177] 2. Gluing strength test

[0178] The following process was used for gluing: single-sided glue application amount (phenolic resin adhesive) 180 g / m 2 , hot pressing temperature 140 °C, hot pressing pressure 2.5 MPa, hot pressing time 70 s / mm. Then, the gluing strength of each group of plywood was tested according to the method of GB / T 17657-1999.

[0179] The test results are as Figure 2 shown.

[0180] It can be Figure 1 , Figure 2 concluded that compared with the control group, the equilibrium contact angle of the bamboo treated by the method of this application becomes smaller, the surface wettability is significantly improved, which is beneficial to the penetration and spreading of the phenolic resin adhesive on its surface, and promotes the improvement of the gluing strength. In addition, by comparing Comparative Examples 1-7 with Example 2, it can be seen that the method for improving the gluing performance of heat-treated bamboo in this application is a whole, and there is a synergistic effect between each step. After the bamboo is treated by the method of this application, the gluing performance has been significantly improved.

Claims

1. A method for improving the gluing performance of heat-treated bamboo, characterized in that, It includes the following steps: S1. Fumigation treatment: After making bamboo into bamboo strips, place them in a fumigation chamber for fumigation treatment, and take them out for standby after completion; S2. Ultrasonic - electric field alternating treatment: Immerse the bamboo strips after fumigation treatment in treatment liquid A, and then conduct ultrasonic - electric field alternating treatment, and take them out for standby after completion; The components and corresponding weight percentages in the treatment liquid A are as follows: ammonium nitrate 3 - 5%, ferric sulfate 1 - 3%, sodium dodecylbenzenesulfonate 7 - 10%, fatty acid glyceride 5 - 9%, calcium silicate 2 - 4%, and the balance is water; S3. Heat treatment: Conduct heat treatment on the bamboo strips treated in step S2 to obtain heat - treated bamboo strips for standby; S4. Spraying - drying cycle treatment: Conduct a cycle treatment of spraying treatment liquid B and drying treatment on the heat - treated bamboo strips. One spraying of treatment liquid B and one drying treatment are one cycle; The components and corresponding weight percentages in the treatment liquid B are as follows: fulvic acid 3 - 6%, lanthanum nitrate 5 - 9%, decanoyl acetaldehyde 0.7 - 0.9%, α - bisabolol 1 - 3%, nano - zinc oxide 5 - 10%, absolute ethanol 20 - 30%, and the balance is pure water; The total number of cycles for the cycle treatment is 4 - 6 cycles.

2. The method for improving the bonding performance of heat-treated bamboo according to claim 1, wherein, The fumigation treatment described in step S1 is steam fumigation, and the time of fumigation treatment is 8 - 10 h.

3. The method for improving the gluing performance of heat-treated bamboo according to claim 1, wherein, The ultrasonic - electric field alternating treatment described in step S2 is specifically: first conduct ultrasonic treatment once, then conduct electric field treatment, and finally conduct ultrasonic treatment twice.

4. The method for improving the gluing performance of heat-treated bamboo according to claim 3, characterized in that, When conducting ultrasonic treatment, insert the ultrasonic probe 2 - 3 cm below the liquid level of the treatment liquid. During treatment, the frequency of ultrasonic waves is controlled at 30 - 50 kHz, the time of the first ultrasonic treatment is 1 - 2 h, and the time of the second ultrasonic treatment is 30 - 40 min.

5. The method for improving the gluing performance of heat-treated bamboo according to claim 3, characterized in that, When conducting electric field treatment, turn on the power supply, control the voltage at 60 - 100 V, and the time of electric field treatment is 8 - 12 min.

6. The method for improving the gluing performance of heat-treated bamboo according to claim 1, characterized in that, The drying treatment described in step S4 is low - temperature vacuum drying treatment, the temperature is 30 - 40 °C, and each time it is dried until the moisture content is 8 - 10%.

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