A bamboo anti-cracking and anti-mildew agent, a preparation method and application thereof

Abstract

The application discloses a kind of bamboo anti-cracking and anti-mildew agent and its preparation method and application.The anti-cracking and anti-mildew agent comprises the following reaction components: polyfurfuryl alcohol, epoxy resin and polyetheramine.The preparation method is as follows: first, furfuryl alcohol is synthesized into polyfurfuryl alcohol with maleic anhydride as catalyst;then the prepared polyfurfuryl alcohol and epoxy resin are mixed uniformly at 50 DEG C, and after cooling to room temperature, polyetheramine is added, and the bamboo anti-cracking and anti-mildew agent is prepared after stirring.The application uses epoxy resin and polyfurfuryl alcohol after compounding for bamboo anti-cracking and anti-mildew, and the bamboo treated by the application can be obviously improved in anti-cracking performance, and also has good anti-mildew performance.

Description

Technical Field

[0001] This invention belongs to the field of bamboo modification and protection, specifically relating to the preparation of a bamboo anti-cracking and anti-mildew agent and its application method in bamboo modification and protection. Background Technology

[0002] Bamboo is a widely distributed renewable biomass resource in China. As a raw material, it can be used in bamboo construction, bamboo handicrafts, bamboo decorations, bamboo-based panels, and composite materials, with a wide range of applications. Compared to other building materials such as steel and concrete, the application of bamboo materials makes construction more environmentally friendly and reduces damage to the natural environment. Bamboo has a carbon sequestration function throughout the entire building lifecycle, making it a sustainable building material. Bamboo has high compressive, tensile, and bending strength, as well as excellent toughness. It is lightweight and high-strength, offering significant advantages over wood. The development of the bamboo industry can effectively fill the domestic timber supply and demand gap. Although round bamboo has natural environmental protection characteristics, high mechanical properties, and aesthetic value, it is prone to deformation and cracking during use, affecting its mechanical properties and appearance. Furthermore, due to its relatively high sugar and starch content, untreated bamboo is susceptible to insect infestation, decay, and mold, resulting in generally poor durability. Mold and cracking in bamboo are closely related; micro-cracks and fissures on the bamboo surface provide conditions for mold invasion and growth. Therefore, simultaneously improving the crack resistance and mildew resistance of bamboo will help expand its application areas, enhance its value, and contribute to the "bamboo-for-wood" and "bamboo-for-plastic" initiatives.

[0003] Bamboo crack and mildew prevention refers to reducing or eliminating cracking or mildew in bamboo through chemical and physical treatments. Existing technologies mainly employ heat treatment, fumigation, surface treatment, and chemical soaking, such as carbonizing bamboo, spraying bamboo with special paints, or soaking bamboo in chemicals for a period of time. However, these methods have drawbacks such as strong odor, high toxicity, short-lasting protection, or unsightly appearance. Currently, there are a few patents for anti-corrosion and anti-cracking agents for bamboo and wood products. These are mainly prepared from metal compounds, isothiazolinone compounds, benzimidazole compounds, castor oil, organic solvents, and surfactants, used to protect wood and bamboo from decay fungi, mold, and termites. However, these components primarily function for corrosion and mildew prevention, and their effect on improving the crack resistance of bamboo is not significant. Impregnating bamboo with phenolic resin, urea-formaldehyde resin, furfuryl alcohol resin, etc., and filling the cell cavities and cell walls after curing, is an effective way to improve the dimensional stability of wood and enhance the crack resistance of bamboo, but it still has drawbacks such as formaldehyde release and brittleness. Epoxy resin is one of the most widely used thermosetting resins, possessing excellent adhesion and mechanical properties, good heat resistance and chemical corrosion resistance, as well as excellent shape memory behavior and unique optical properties. It has been widely used in adhesives, coatings, and fiber composites. Furfuryl alcohol, a catalytic reduction product of furfural, is mainly prepared from agricultural by-products such as sugarcane bagasse, corn cobs, and wheat straw. Polyfurfuryl alcohol, produced through polycondensation, exhibits good heat and chemical resistance and has been applied in metal casting, adhesives, and coatings. Polyfurfuryl alcohol contains active groups such as hydroxyl and carbonyl groups, which can be chemically incorporated into the crosslinking network of epoxy resins to regulate its properties. Polyfurfuryl alcohol-modified epoxy resins have significant advantages in the modification and protection of bamboo materials. Summary of the Invention

[0004] To address the problems of bamboo's susceptibility to cracking and mold growth in the prior art, this invention discloses a bamboo anti-cracking and anti-mold agent and its application method in bamboo modification and protection.

[0005] The technical solution adopted in this invention is as follows:

[0006] I. A bamboo anti-cracking and anti-mildew agent

[0007] The anti-crack and anti-mildew agent comprises the following components in parts by weight:

[0008] Polyfurfuryl alcohol 3.5–15.2

[0009] Epoxy resin 72.5~59.3

[0010] Polyetheramine 24.0–25.5

[0011] The polyfurfuryl alcohol is obtained by polycondensation of furfuryl alcohol using maleic anhydride as a catalyst, with a molecular weight of 918 g / mol and a polydispersity index of 2.05. The preferred weight percentage of the polyfurfuryl alcohol is 10%, as excessively high polyfurfuryl alcohol content will reduce the mechanical properties of the anti-cracking and anti-mildew agent.

[0012] The epoxy value of the epoxy resin is 0.41 to 0.54;

[0013] The polyetheramine is D230 or D400.

[0014] II. Preparation method of bamboo anti-cracking and anti-mildew agent

[0015] Includes the following steps:

[0016] 1) Using maleic anhydride as a catalyst, furfuryl alcohol is synthesized into polyfurfuryl alcohol;

[0017] 2) The prepared polyfurfuryl alcohol and epoxy resin were mixed at 50°C, cooled to room temperature, and then polyetheramine was added. After stirring, the bamboo anti-cracking and anti-mildew agent was obtained.

[0018] In step 2), the blending conditions are: blending in a 50°C water bath for 1 hour; and stirring for 15 minutes after adding polyetheramine at room temperature.

[0019] III. Application of anti-cracking and anti-mildew agents in bamboo modification

[0020] 1) Immerse the round bamboo to be treated in an anti-cracking and anti-mildew agent;

[0021] 2) Subsequently, the round bamboo was subjected to vacuum pressurization treatment, and kept under vacuum and pressurization conditions for a period of time respectively;

[0022] 3) After the pressure is applied, the round bamboo is taken out and heated to cure. After curing, the round bamboo is taken out, and the modified bamboo with anti-cracking and anti-mildew properties is obtained.

[0023] In step 2), the round bamboo is first kept under a vacuum of 0.06 MPa for 15 minutes, and then the pressure is increased to 0.8 MPa and kept for 30 minutes.

[0024] In step 3), the product is heated and cured in an oven at 80°C for 6 hours.

[0025] Electron microscopy revealed that the morphological structure of the round bamboo treated according to this invention was filled with a large amount of anti-crack and anti-mold agent inside the cell cavity, and the vascular bundles of the bamboo were completely filled with the anti-crack and anti-mold agent.

[0026] The anti-cracking and anti-mildew agent used in this invention differs from conventional treatment agents; it is environmentally friendly and harmless. Furthermore, by utilizing polyfurfuryl alcohol-modified epoxy resin, the shape memory response temperature of the anti-cracking and anti-mildew agent is lowered, and its shape memory function is used to enhance the crack resistance of bamboo.

[0027] This invention combines epoxy resin and polyfurfuryl alcohol for crack and mildew prevention in bamboo. The raw materials are environmentally friendly and abundant, and have anti-mildew and shape memory properties, thus achieving the dual functions of crack prevention and mildew prevention in bamboo.

[0028] The beneficial effects of this invention are:

[0029] The processing method of this invention is simple, non-toxic, and produces no irritating odor in the treated material. Furthermore, bamboo treated with this invention exhibits significantly improved crack resistance and good mold resistance. Attached Figure Description

[0030] Figure 1 This is a graph showing the experimental results comparing the shape memory performance of PFA / EP / PEA in Example 2 with that of EP / PEA in Example 1.

[0031] Figure 2 This is a diagram showing the infection status of bamboo treated in Example 2 during the anti-mold test (left: treated material; right: untreated material).

[0032] Figure 3 This is a diagram showing the infection status of the raw bamboo after comprehensive anti-mold testing following treatments in Examples 1 and 2. Detailed Implementation

[0033] The present invention will be further described below with reference to embodiments.

[0034] The present invention can be implemented using the following embodiments, but is not limited to the following embodiments.

[0035] I. Preparation and Treatment Process of Bamboo Anti-Crack and Anti-Mold Agent

[0036] Example 1

[0037] Preparation of bamboo anti-cracking and anti-mildew agent: Weigh 500g of epoxy resin (E51) and 175g of polyetheramine (D230), and stir quickly for 15 minutes to obtain the bamboo anti-cracking and anti-mildew agent.

[0038] Processing procedure: Immerse round bamboo in an anti-crack and anti-mildew agent, first maintain a vacuum of 0.06MPa for 15 minutes, then pressurize to 0.8MPa and maintain for 30 minutes; after pressurization, remove the round bamboo and place it in 80℃ for curing for 6 hours; after curing, bamboo with anti-crack and anti-mildew properties is obtained.

[0039] Example 2

[0040] Preparation of polyfurfuryl alcohol: Heat 36g of water to 92℃, then add 0.18g of maleic anhydride and stir for 5-10 minutes; then add 100g of furfuryl alcohol dropwise to the water containing the catalyst. Reflux at 92℃ for 1 hour, then cool to 50℃ and add an appropriate amount of NaOH solution (5wt%) to adjust the pH to approximately 7.0 to obtain the crude product. Dissolve the crude product in dichloromethane, wash three times or more with saturated brine and distilled water, and remove the dichloromethane by rotary evaporation to obtain polyfurfuryl alcohol.

[0041] Preparation of bamboo anti-cracking and anti-mildew agent: Weigh 100g of epoxy resin (E51) and 15g of polyfurfuryl alcohol, mix them at 50℃ for 1 hour, cool them, add 38g of polyetheramine (D230) and stir rapidly for 15 minutes to obtain the bamboo anti-cracking and anti-mildew agent.

[0042] Processing procedure: Immerse round bamboo in an anti-crack and anti-mildew agent, first maintain a vacuum of 0.06MPa for 15 minutes, then pressurize to 0.8MPa and maintain for 30 minutes; after pressurization, remove the round bamboo and place it in 80℃ for curing for 6 hours; after curing, bamboo with anti-crack and anti-mildew properties is obtained.

[0043] Example 3

[0044] Preparation of polyfurfuryl alcohol: Heat 72g of water to 92℃, then add 0.36g of maleic anhydride and stir for 5-10 minutes; then add 200g of furfuryl alcohol dropwise to the water containing the catalyst. Reflux at 92℃ for 1 hour, then cool to 50℃ and add an appropriate amount of NaOH solution (5wt%) to adjust the pH to approximately 7.0 to obtain the crude product. Dissolve the crude product in dichloromethane, wash three times or more with saturated brine and distilled water, and remove the dichloromethane by rotary evaporation to obtain polyfurfuryl alcohol.

[0045] Preparation of bamboo anti-cracking and anti-mildew agent: Weigh 1.25kg epoxy resin (E51) and 0.06kg polyfurfuryl alcohol, mix them at 50℃ for 1h, cool them and add 0.41kg polyetheramine (D230) and stir rapidly for 15min to obtain the bamboo anti-cracking and anti-mildew agent.

[0046] Processing procedure: Immerse round bamboo in an anti-crack and anti-mildew agent, first maintain a vacuum of 0.06MPa for 15 minutes, then pressurize to 0.8MPa and maintain for 30 minutes; after pressurization, remove the round bamboo and place it in 80℃ for curing for 6 hours; after curing, bamboo with anti-crack and anti-mildew properties is obtained.

[0047] Example 4

[0048] Preparation of polyfurfuryl alcohol: Heat 72g of water to 92℃, then add 0.36g of maleic anhydride and stir for 5 minutes; then add 200g of furfuryl alcohol dropwise to the water containing the catalyst. Reflux at 92℃ for 1 hour, then cool to 50℃ and add an appropriate amount of NaOH solution (5wt%) to adjust the pH to approximately 7.0, thus obtaining the crude product. Dissolve the crude product in dichloromethane, wash three times or more with saturated brine and distilled water, and remove the dichloromethane by rotary evaporation to obtain polyfurfuryl alcohol.

[0049] Preparation of bamboo anti-cracking and anti-mildew agent: Weigh 0.5 kg of epoxy resin (E51) and 0.1 kg of polyfurfuryl alcohol, mix them at 50℃ for 1 h, cool them, add 0.2 kg of polyetheramine (D230) and stir rapidly for 15 min to obtain the bamboo anti-cracking and anti-mildew agent.

[0050] Processing procedure: Immerse round bamboo in an anti-crack and anti-mildew agent, first maintain a vacuum of 0.06MPa for 15 minutes, then pressurize to 0.8MPa and maintain for 30 minutes; after pressurization, remove the round bamboo and place it in 80℃ for curing for 6 hours; after curing, bamboo with anti-crack and anti-mildew properties is obtained.

[0051] II. Crack-resistant effect of bamboo

[0052] To determine the crack-resistant effect of this invention, two experimental schemes were designed. The first experimental scheme was a hot-cold cycle experiment, in which the treated material was placed in an oven at 103±2℃ for 2 hours to dry, then removed and cooled to room temperature; this process was repeated three times, and the number of cracked bamboo shoots in each cycle was counted. The second experimental scheme involved continuously heating the treated material in an oven at 103±2℃ for 6 hours, and the number of cracked bamboo shoots was counted every hour. The experimental results are shown in Tables 1 and 2.

[0053] Table 1 shows the percentage of cracked bamboo shoots among the total number of bamboo shoots tested during the heat-cold cycle. In the first heat-cold cycle, 41.7% of the untreated bamboo shoots showed cracking; in the second cycle, this increased to 50%; and by the end of the third cycle, 75% of the untreated bamboo shoots had cracked. The treated bamboo shoots, however, showed no cracking after three heat-cold cycles.

[0054] Table 2 shows the percentage of round bamboo that cracked after a 6-hour heating experiment. Untreated round bamboo cracked during the first hour of heating, while treated bamboo showed no cracking at this time. After four hours of heating, 50% of the untreated bamboo cracked. By the fifth hour, 16.7% of the treated bamboo had cracked, compared to 83.3% of the untreated bamboo. By the sixth hour, all untreated bamboo had cracked, while only 33.3% of the treated bamboo had cracked.

[0055] Table 1. Percentage of round bamboo cracking during heat-cold cycling experiments

[0056] 1 41.7％ 0％ 0％ 2 50％ 8.3％ 0％ 3 75％ 16.7％ 0％

[0057] Table 2. Percentage of round bamboo cracking during six-hour continuous heating experiment

[0058]

[0059]

[0060] Figure 1 The combination of epoxy resin and polyfurfuryl alcohol demonstrates superior shape memory properties:

[0061] like Figure 1 As shown in a and b, the shape recovery time of PFA / EP / PEA in Example 2 is shorter than that of EP / PEA in Example 1, indicating that the shape memory response of PFA / EP / PEA in Example 2 is faster, which is more conducive to improving the crack resistance of round bamboo.

[0062] like Figure 1 As shown in c, in multiple cyclic tests, the shape recovery time of PFA / EP / PEA in Example 2 was shorter than that of EP / PEA in Example 1, indicating that PFA / EP / PEA in Example 2 has good shape memory function and stability.

[0063] III. Anti-mildew effect of bamboo

[0064] The anti-mold test was conducted according to the relevant provisions of GB / T 18261-2013 "Test Methods for the Preventive Efficacy of Anti-mold Agents against Wood Molds and Discoloration Fungi". The anti-mold effects of the treated material against *Trichoderma viride*, *Penicillium citrinum*, and *Aspergillus niger* were as follows: Figure 2 As shown in the diagram. In each petri dish, the left side represents the treated material, and the right side represents the untreated material. On day 5, *Trichoderma viride* and *Penicillium citrinum* had infected about half of the surface area of ​​the untreated material, while *Aspergillus niger* had infected the entire surface of the untreated material. No traces of mold infection were found on the treated material. By day 15, all three molds had completely infected the surface of the untreated material, while only traces of mold were found near the edges of the treated material, with only a small amount of infection at the edges. By day 30, the treated material showed varying degrees of resistance to the three molds. *Trichoderma viride* had the smallest infected area, with a damage value of 1, indicating that the treated material had a high control efficacy against *Trichoderma viride*. *Penicillium citrinum* had a damage value of 2 on the treated material, and *Aspergillus niger* had a damage value of 3, both showing a decrease compared to the untreated material.

[0065] In addition, the raw bamboo treated in Examples 1 and 2 underwent a comprehensive anti-mold test for 30 days according to the AWPA E24-06 standard. The infection status of the samples was as follows: Figure 3 As shown, by day 4 of the test, the cross-section of untreated bamboo was covered with mold, while the cross-sections of EP / PEA and PFA / EP / PEA treated bamboo showed almost no mold. By day 30, about one-third of the cross-section of EP / PEA treated bamboo was infected with mold, while the cross-sections of PFA / EP / PEA treated bamboo still showed almost no mold.

[0066] The above test results demonstrate that the bamboo treated by this invention has a good anti-mildew effect.

Claims

1. A bamboo anti-cracking and anti-mildew agent, characterized in that, The crack-resistant and mildew-resistant agent comprises the following components: Polyfurfural 3.5–15.2% Epoxy resin 72.5%–59.3% Polyetheramine 24.0–25.5% The polyfurfuryl alcohol is obtained by polycondensation of furfuryl alcohol using maleic anhydride as a catalyst, with a molar mass of 918 g / mol and a polydispersity index of 2.

05.

2. The bamboo anti-cracking and anti-mildew agent according to claim 1, characterized in that, The content of polyfurfuryl alcohol is 10%.

3. The bamboo anti-cracking and anti-mildew agent according to claim 1, characterized in that, The epoxy value of the epoxy resin is 0.41 to 0.54; The polyetheramine is D230 or D400.

4. The method for preparing the bamboo anti-cracking and anti-mildew agent according to any one of claims 1 to 3, characterized in that: Includes the following steps: 1) Using maleic anhydride as a catalyst, furfuryl alcohol is synthesized into polyfurfuryl alcohol; 2) The prepared polyfurfuryl alcohol and epoxy resin are mixed at 50°C, cooled to room temperature, and then polyetheramine is added. After stirring, the bamboo anti-cracking and anti-mildew agent is obtained.

5. The preparation method of the bamboo anti-cracking and anti-mildew agent according to claim 4, characterized in that, In step 2): The blending conditions were: blending in a 50°C water bath for 1 hour; stirring time after adding polyetheramine at room temperature was 15 minutes.

6. The application of the anti-cracking and anti-mildew agent according to any one of claims 1 to 3 in the modification of bamboo, characterized in that, 1) Immerse the round bamboo to be treated in an anti-cracking and anti-mildew agent; 2) Subsequently, the round bamboo was subjected to vacuum pressurization treatment, and kept under vacuum and pressurization conditions for a period of time respectively; 3) After the pressure is applied, the round bamboo is taken out and heated to cure. After curing, the round bamboo is taken out, and the modified bamboo with anti-cracking and anti-mildew properties is obtained. In step 2), the round bamboo is kept under a vacuum of 0.06 MPa for 15 minutes; In step 2), the round bamboo is pressurized to 0.8 MPa and maintained for 30 minutes; In step 3), the round bamboo is placed in an oven for heating and curing at a temperature of 80°C for 6 hours.

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