Polylactic acid-based full-degradable environment-friendly furniture board and preparation method thereof

Abstract

The invention relates to a polylactic acid-based full-degradable environment-friendly furniture board and a preparation method thereof, and belongs to the technical field of composite environment-friendly furniture boards, steric composite polylactic acid fibers, composite basalt fiber aerogel and bamboo fibers are mixed, then banburying is performed, and compression molding is performed to obtain the polylactic acid-based full-degradable environment-friendly furniture board. The stereo-composite homogeneous crystals in the stereo-composite polylactic acid fiber are almost completely melted and converted into stereo-composite crystals, the crystal structure is more stable, the creep resistance at high temperature is improved, in addition, the structure formed by the composite basalt fiber aerogel can further fill pores of the stereo-composite polylactic acid fiber, and the creep resistance of the stereo-composite polylactic acid fiber is improved. The composite basalt fiber aerogel treated by trimethylchlorosilane has a large contact angle, water molecule permeation is blocked, and the heat resistance of the polylactic acid-based fully-degradable environment-friendly furniture board is improved through the synergistic effect of the composite basalt fiber aerogel and the trimethylchlorosilane, so that the heat resistance of the furniture board is improved. And the chitosan and the bamboo fiber can play a role in inhibiting the growth of microorganisms.

Description

Technical Field

[0001] The invention belongs to the technical field of composite environmentally friendly furniture boards and relates to a polylactic acid-based fully degradable environmentally friendly furniture board and a preparation method thereof. Background Art

[0002] Polylactic acid (PLA) is a biodegradable polyester made from starch from plants like corn and wheat. It's a polymer material produced through fermentation to produce lactic acid, which is then polymerized. The ester bonds in its molecular chain are easily hydrolyzed and can be completely degraded into carbon dioxide and water by microorganisms in the natural environment, without causing any environmental pollution. PLA synthesis methods include direct polycondensation and intermediate ring-opening polymerization. The direct polycondensation method synthesizes PLA through the condensation of lactic acid monomers, while the intermediate ring-opening polymerization method uses lactide as an intermediate, which is formed through the dehydration condensation of lactic acid monomers. The intermediate then undergoes ring-opening polymerization in the presence of a catalyst to produce PLA.

[0003] Chinese invention application publication number CN111057356B discloses a polylactic acid-based biomass composite board and its preparation method. The board is composed of polylactic acid, polybutylene succinate, modified straw powder, a talc / lignin composite, and the plasticizers DOP and acetyl tributyl citrate. The board is biodegradable, non-toxic, lightweight, high-strength, and heat-resistant. It is safe and environmentally friendly during use, reducing the cost of polylactic acid and expanding the application of agricultural waste. The molding process is relatively simple, quick, and convenient, with strong design flexibility. It can produce products of various shapes at a low cost. It can be used to make disposable products such as in-ground flower pots, gift boxes, and disposable lunch boxes.

[0004] However, if the polylactic acid-based biomass composite material board prepared in the above patent is used as furniture board, especially in a high humidity and heat place such as the kitchen, it is easy to cause the material to soften and deform, and the residual grease in the kitchen will provide a nutrient source for microorganisms, which will easily breed microorganisms, significantly accelerate the degradation rate of polylactic acid, and shorten the service life of the board. Summary of the Invention

[0005] The purpose of the present invention is to provide a polylactic acid-based fully degradable environmentally friendly furniture board and a preparation method thereof. The board is obtained by mixing and kneading stereocomposite polylactic acid fibers, composite basalt fiber aerogel and bamboo fibers, and then compression molding them, so as to improve the moisture and heat resistance and mechanical properties of the board.

[0006] The purpose of the present invention can be achieved through the following technical solutions: The preparation method of polylactic acid-based fully degradable environmentally friendly furniture board comprises the following steps: Step 1: etching the surface of the basalt fiber through plasma treatment to obtain surface-etched basalt fiber.

[0007] Step 2: Using tetraethyl orthosilicate as a silicon source to generate silicon dioxide and compounding it with chitosan to obtain a composite sol precursor solution, and mixing the composite precursor solution with surface-etched basalt fiber to obtain a composite basalt fiber aerogel.

[0008] Step 3: Combine poly (L-lactic acid) powder, poly (D-lactic acid) powder and poly (butylene adipate / terephthalate) powder together by melt blending to obtain stereocomposite poly (lactic acid) fiber.

[0009] Step 4: Add the stereocomposite polylactic acid fiber, composite basalt fiber aerogel, and bamboo fiber into the torque rheometer, perform internal mixing, and perform compression molding to obtain polylactic acid-based fully biodegradable and environmentally friendly furniture panels.

[0010] Furthermore, the preparation process of surface-etched basalt fiber is as follows: The basalt fiber and acetone solution are added to a reactor, ultrasonically cleaned, washed, and dried, and then placed in a quartz tube of a low-temperature plasma generator. Vacuuming is started in a sealed state, and oxygen is supplied under the conditions of 35-50 Pa and 15-20 r / min. After plasma treatment, the equipment is closed, cooled to room temperature, and the vacuum degree is restored to atmospheric pressure to obtain surface-etched basalt fiber.

[0011] Furthermore, the discharge power of the plasma treatment is 120-130 W, the discharge time is 200-320 s, and the oxygen flow rate is 20-30 mL / min.

[0012] Furthermore, the preparation process of the composite sol precursor solution is as follows: Add ethyl orthosilicate, anhydrous ethanol and deionized water into a reactor, adjust the pH value to 2-3 with hydrochloric acid, hydrolyze at 30-40°C and 500-600r / min for 12-14h, add 3wt% chitosan glacial acetic acid solution, and stir at 23-25°C for 5-7min to obtain a composite sol precursor solution.

[0013] Furthermore, the usage ratio of ethyl orthosilicate, anhydrous ethanol, deionized water and chitosan glacial acetic acid solution is 270-300 g: 630-700 mL: 100-120 mL: 200-300 mL.

[0014] Furthermore, the preparation process of composite basalt fiber aerogel is as follows: The composite precursor solution and surface-etched basalt fiber are added to a reactor, aged at 20-25° C. for 48-50 hours, filtered, and the precipitate, trimethylchlorosilane, and anhydrous ethanol are added to the reactor, soaked for 12-14 hours, washed, extracted with supercritical carbon dioxide at 50-60° C. and 12-13 MPa for 12-14 hours, cooled, and decompressed to obtain a composite basalt fiber aerogel.

[0015] Furthermore, the usage ratio of the composite precursor solution and the surface-etched basalt fiber is 500-600 mL: 50-60 g.

[0016] Furthermore, the usage ratio of the precipitate, trimethylchlorosilane and anhydrous ethanol is 50-60 g: 10-15 mL: 90-100 mL.

[0017] Furthermore, the preparation process of the stereocomposite polylactic acid fiber is as follows: Poly (L-lactic acid) powder, poly (D-lactic acid) powder and poly (butylene adipate) terephthalate powder are mixed evenly, and the mixed powder is fed into a single-screw extruder with a melting temperature of 185-195°C and a screw speed of 120-150 r / min. The melt is directed to a winding drum with a speed of 250-300 r / min to obtain spun fibers. The spun fibers are drawn at 120-140°C with a drawing ratio of 3. The drawn fibers are annealed at 160-200°C for 20-30 minutes with a tension of 10-12 MPa to obtain stereocomposite polylactic acid fibers.

[0018] Furthermore, the mass ratio of the poly (L-lactic acid) powder, the poly (D-lactic acid) powder and the poly (adipate / butylene terephthalate) powder is 50-70:50-70:5-6.

[0019] Furthermore, the preparation process of the polylactic acid-based fully biodegradable environmentally friendly furniture board is as follows: The stereocomposite polylactic acid fiber, composite basalt fiber aerogel and bamboo fiber with a length of 20-30 mm were added to the torque rheometer, mixed for 8-10 minutes, and then molded using a flat vulcanizing machine with a molding time of 300-320 seconds and a cooling time of 300-320 seconds to obtain polylactic acid-based fully biodegradable and environmentally friendly furniture panels.

[0020] Furthermore, the mass ratio of the stereocomposite polylactic acid fiber, the composite basalt fiber aerogel and the bamboo fiber is 80-100:20-30:20-30.

[0021] Furthermore, the temperature of the banburying treatment is 170-180° C., and the rotation speed is 30-60 r / min.

[0022] Furthermore, the molding temperature is 190-200° C., the molding pressure is 10-15 MPa, the exhaust stroke is 5-6 cm, and the exhaust times are 30-40 times.

[0023] Beneficial effects of the present invention: 1. The polylactic acid-based fully degradable and environmentally friendly furniture board in the present invention is obtained by mixing stereocomposite polylactic acid fibers, composite basalt fiber aerogels and bamboo fibers, performing internal kneading, and then compression molding. The stereocomposite homogeneous crystals in the stereocomposite polylactic acid fibers are almost completely melted and converted into stereocomposite crystals. The crystal structure is more stable, and the creep resistance at high temperatures is improved. In addition, the structure formed by the composite basalt fiber aerogel can further fill the pores of the stereocomposite polylactic acid fibers, thereby inhibiting the thermal motion of the molecular segments of the stereocomposite polylactic acid fibers. The two synergistically improve the heat resistance of the polylactic acid-based fully degradable and environmentally friendly furniture board. In addition, the composite basalt fiber aerogel treated with trimethylchlorosilane has a large contact angle, which blocks the penetration of water molecules. Chitosan and bamboo fiber can inhibit the growth of microorganisms, reduce the degradation of the board by microorganisms, and extend the service life of the board in a high humidity and heat environment.

[0024] 2. In the present invention, the surface of the basalt fiber is etched by plasma treatment to increase the roughness of the surface of the basalt fiber, and then an aerogel composite of silica and chitosan is formed on its surface. The increase in roughness provides more attachment sites for the aerogel sol, which enables chitosan to be evenly attached to the surface of the etched basalt fiber, thereby increasing the loading rate and allowing chitosan to be evenly distributed inside the polylactic acid-based fully degradable and environmentally friendly furniture board. In addition, hydrogen bonds can be formed between the amino groups of chitosan and the silanol groups of silica, thereby enhancing the interfacial bonding between the two. The plasma-treated surface-etched basalt fiber also enhances the interfacial bonding between it and the stereocomposite polylactic acid fiber.

[0025] 3. In the present invention, poly (L-lactic acid) powder, poly (D-lactic acid) powder and poly (butylene adipate) terephthalate powder are mixed and then melted. During this process, the activity of the enantiomeric macromolecules of the poly (L-lactic acid) powder and poly (D-lactic acid) powder is enhanced and rearranged to form regular stereocomposite crystals. In addition, a good cross-linking network is formed between the poly (L-lactic acid) powder, poly (D-lactic acid) powder and poly (butylene adipate) terephthalate powder, which can further improve the toughness of the board. The bamboo fiber can absorb impact energy, which synergistically improves the toughness and impact resistance of the poly (lactic acid)-based fully degradable and environmentally friendly furniture board. DETAILED DESCRIPTION

[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, features and effects of the present invention are described in detail below in combination with preferred embodiments.

[0027] Example 1: This example provides a polylactic acid-based fully degradable environmentally friendly furniture board, which is prepared by the following steps: S1: 275 g of basalt fiber and 2.5 L of acetone solution were added to the reactor, ultrasonically cleaned for 1.5 h, washed with deionized water 4 times, dried at 65 ° C for 13 h, and then placed in the quartz tube of the low-temperature plasma generator. The vacuum was turned on in a sealed state. Under the condition of a vacuum degree of 42 Pa, the quartz tube speed knob was turned on and the speed was set to 17 r / min. The air inlet valve was opened and oxygen was supplied at a rate of 25 mL / min. The discharge power was set to 125 W and the discharge time was set to 310 s. The surface of the basalt fiber was etched. After the plasma treatment was completed, the RF power was turned off and the vacuum was stopped and the gas was released after the equipment cooled down. When the vacuum degree returned to atmospheric pressure, the sample was taken out to obtain surface-etched basalt fiber.

[0028] S2: Add 285g of ethyl orthosilicate, 665mL of anhydrous ethanol and 110mL of deionized water into a reactor, adjust the pH value to 2 with hydrochloric acid, hydrolyze at 35°C and 550r / min for 13h, add 250mL of 3wt% chitosan glacial acetic acid solution, and stir at 24°C for 6min to obtain a composite sol precursor solution.

[0029] S3: Add 550 mL of the composite precursor solution and 55 g of surface-etched basalt fiber into the reactor, age at 22 ° C for 49 h, filter, remove the filtrate, add 55 g of the precipitate, 12 mL of trimethylchlorosilane and 95 mL of anhydrous ethanol into the reactor, soak for 13 h, rinse with anhydrous ethanol 4 times, extract with supercritical carbon dioxide at 55 ° C and 12 MPa for 13 h, remove the solvent, stop heating, and reduce the pressure to atmospheric pressure to obtain a composite basalt fiber aerogel.

[0030] S4: 60g of poly (L-lactic acid) powder, 60g of poly (D-lactic acid) powder and 5.5g of poly (butylene adipate / terephthalate) powder were mixed evenly, and the mixed powder was fed into a single-screw extruder with a melting temperature of 190°C and a screw speed of 135r / min. The melt was directed to a winding drum with a speed of 275r / min to obtain spun fibers. The spun fibers were stretched at 130°C with a stretching ratio of 3. The stretched fibers were annealed at 180°C for 25min with a tension of 11MPa. During the melt blending process, the activity of the enantiomeric macromolecules of poly (L-lactic acid) and poly (D-lactic acid) was enhanced and rearranged to form regular stereocomposite crystals to obtain stereocomposite polylactic acid fibers.

[0031] S5: Add 90g of stereocomposite polylactic acid fiber, 25g of composite basalt fiber aerogel and 25g of bamboo fiber with a length of 20-30mm into the torque rheometer, set the mixing temperature to 175℃, the rotor speed to 45r / min, the mixing time to 9min, and then use a flat vulcanizing press for compression molding. The molding temperature is 195℃, the molding pressure is 12MPa, the exhaust stroke is 5cm, the exhaust times are 35 times, the molding time is 310s, and the cooling time is 310s to obtain polylactic acid-based fully degradable and environmentally friendly furniture panels.

[0032] Example 2: This example provides a polylactic acid-based fully degradable environmentally friendly furniture board, which is prepared by the following steps: S1: Add 250g of basalt fiber and 2L of acetone solution into the reactor, ultrasonically clean for 1h, wash with deionized water 3 times, dry at 60℃ for 12h, and then place it in the quartz tube of the low-temperature plasma generator. Start vacuuming in a sealed state. Under the condition of vacuum degree of 35Pa, open the quartz tube speed knob and set the speed to 15r / min. Open the air inlet valve and supply oxygen at a rate of 20mL / min. Set the discharge power to 120W and the discharge time to 300s to etch the surface of the basalt fiber. After the plasma treatment is completed, turn off the RF power supply, stop vacuuming and releasing the gas after the equipment cools down, and take out the sample when the vacuum degree returns to atmospheric pressure to obtain surface-etched basalt fiber.

[0033] S2: Add 270 g of ethyl orthosilicate, 630 mL of anhydrous ethanol and 100 mL of deionized water into a reactor, adjust the pH value to 2 with hydrochloric acid, hydrolyze at 30 ° C and 500 r / min for 12 h, add 200 mL of 3 wt% chitosan glacial acetic acid solution, and stir at 23 ° C for 5 min to obtain a composite sol precursor solution.

[0034] S3: Add 500 mL of the composite precursor solution and 50 g of surface-etched basalt fiber into the reactor, age at 20°C for 48 h, filter, remove the filtrate, add 50 g of the precipitate, 10 mL of trimethylchlorosilane and 90 mL of anhydrous ethanol into the reactor, soak for 12 h, rinse with anhydrous ethanol three times, extract with supercritical carbon dioxide at 50°C and 12 MPa for 12 h, remove the solvent, stop heating, and reduce the pressure to atmospheric pressure to obtain a composite basalt fiber aerogel.

[0035] S4: 50g of poly (L-lactic acid) powder, 50g of poly (D-lactic acid) powder and 5g of poly (butylene adipate / terephthalate) powder were mixed evenly, and the mixed powder was fed into a single-screw extruder with a melting temperature of 185°C and a screw speed of 120r / min. The melt was directed to a winding drum with a speed of 250r / min to obtain spun fibers. The spun fibers were stretched at 120°C with a stretching ratio of 3. The stretched fibers were annealed at 160°C for 20min with a tension of 10MPa. During the melt blending process, the activity of the enantiomeric macromolecules of poly (L-lactic acid) and poly (D-lactic acid) was enhanced and rearranged to form regular stereocomposite crystals to obtain stereocomposite polylactic acid fibers.

[0036] S5: Add 80g of stereocomposite polylactic acid fiber, 20g of composite basalt fiber aerogel and 20g of bamboo fiber with a length of 20-30mm into the torque rheometer, set the mixing temperature to 170℃, the rotor speed to 30r / min, the mixing time to 8min, and then use a flat vulcanizing press for compression molding. The molding temperature is 190℃, the molding pressure is 10MPa, the exhaust stroke is 5cm, the exhaust times are 30 times, the molding time is 300s, and the cooling time is 300s to obtain polylactic acid-based fully degradable and environmentally friendly furniture panels.

[0037] Example 3: This example provides a polylactic acid-based fully degradable environmentally friendly furniture board, which is prepared by the following steps: S1: 300 g of basalt fiber and 3 L of acetone solution were added to the reactor, ultrasonically cleaned for 2 h, washed with deionized water 5 times, dried at 70 ° C for 14 h, and then placed in the quartz tube of the low-temperature plasma generator. The vacuum was turned on in a sealed state. Under the condition of a vacuum degree of 50 Pa, the quartz tube speed knob was turned on and the speed was set to 20 r / min. The air inlet valve was opened and oxygen was supplied at a rate of 30 mL / min. The discharge power was set to 130 W and the discharge time was set to 320 s. The surface of the basalt fiber was etched. After the plasma treatment was completed, the RF power was turned off and the vacuum was stopped after the equipment cooled down to release the gas. When the vacuum degree returned to atmospheric pressure, the sample was taken out to obtain surface-etched basalt fiber.

[0038] S2: 300 g of ethyl orthosilicate, 700 mL of anhydrous ethanol and 120 mL of deionized water were added to a reactor, the pH value was adjusted to 3 with hydrochloric acid, and hydrolysis was carried out at 40 ° C and 600 r / min for 14 h. 300 mL of 3 wt% chitosan glacial acetic acid solution was added and stirred at 25 ° C for 7 min to obtain a composite sol precursor solution.

[0039] S3: Add 600 mL of the composite precursor solution and 60 g of surface-etched basalt fiber into the reactor, age at 25 ° C for 50 h, filter, remove the filtrate, add 60 g of the precipitate, 15 mL of trimethylchlorosilane and 100 mL of anhydrous ethanol into the reactor, soak for 14 h, rinse with anhydrous ethanol 5 times, extract with supercritical carbon dioxide at 60 ° C and 13 MPa for 14 h, remove the solvent, stop heating, and reduce the pressure to atmospheric pressure to obtain a composite basalt fiber aerogel.

[0040] S4: 70g of poly (L-lactic acid) powder, 70g of poly (D-lactic acid) powder and 6g of poly (butylene adipate / terephthalate) powder were mixed evenly, and the mixed powder was fed into a single-screw extruder with a melting temperature of 195°C and a screw speed of 150r / min. The melt was directed to a winding drum with a speed of 300r / min to obtain spun fibers. The spun fibers were stretched at 140°C with a stretching ratio of 3 times. The stretched fibers were annealed at 200°C for 30min with a tension of 12MPa. During the melt blending process, the activity of the enantiomeric macromolecules of poly (L-lactic acid) and poly (D-lactic acid) was enhanced and rearranged to form regular stereocomposite crystals to obtain stereocomposite polylactic acid fibers.

[0041] S5: Add 100g of stereocomposite polylactic acid fiber, 30g of composite basalt fiber aerogel and 30g of bamboo fiber with a length of 20-30mm into the torque rheometer, set the mixing temperature to 180℃, the rotor speed to 60r / min, the mixing time to 10min, and then use a flat vulcanizing press for compression molding. The molding temperature is 200℃, the molding pressure is 15MPa, the exhaust stroke is 6cm, the number of exhaust times is 40 times, the molding time is 320s, and the cooling time is 320s to obtain polylactic acid-based fully degradable and environmentally friendly furniture panels.

[0042] Comparative Example 1: Based on Example 1, the composite basalt fiber aerogel is removed from step S5, and the remaining steps remain unchanged to prepare a polylactic acid-based fully degradable and environmentally friendly furniture board.

[0043] Comparative Example 2: Based on Example 1, the chitosan glacial acetic acid solution is removed in step S2 to prepare a single sol precursor solution, and the prepared single sol precursor solution is used to replace the composite precursor solution in step S3. The other steps remain unchanged to prepare polylactic acid-based fully degradable and environmentally friendly furniture panels.

[0044] Comparative Example 3: Based on Example 1, step S1 is omitted, basalt fiber is used instead of surface-etched basalt fiber in step S3, and the other steps remain unchanged to prepare a polylactic acid-based fully degradable and environmentally friendly furniture board.

[0045] Comparative Example 4: Based on Example 1, step S4 is omitted, and in step S5, polylactic acid pellets are used instead of stereocomposite polylactic acid fibers, and the remaining steps remain unchanged to prepare polylactic acid-based fully degradable and environmentally friendly furniture panels.

[0046] The performance of the polylactic acid-based fully degradable environmentally friendly furniture panels prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested: Tensile Properties Test: Referring to GB / T1040.2-2006, the composite material was pressed into 1mm thick sheets. Standard test specimens were then cut using a dumbbell-shaped punch cutter. Tensile properties were tested using a universal testing machine at a tensile rate of 2mm / min. Five specimens were tested for each material group, and the average value was used as the test result. Impact performance test: Referring to GB / T1843.2-2008 standard, the composite material was pressed into a 4mm thick plate. First, several rectangular test specimens were cut with an electric saw. Then, a triangular notch with a depth of 2mm was milled in the middle of the specimen using a chamfering machine. The impact performance was tested using a pendulum impact tester. Five specimens were tested for each group of samples, and the average value was taken as the test result. Heat resistance test: Use an electronic analytical balance to weigh 6-8mg of sample and place it in a quartz crucible. Then place the quartz crucible in a thermogravimetric analyzer. Set the temperature test range to 30-700°C, the heating rate to 10°C / min, and the nitrogen purge flow rate in the furnace to 20mL / min. The temperature index is related to the temperature at which the material loses 5% and 30% of its weight. It can represent the long-term operating temperature of the material, and its value can be used to measure the thermal stability of the material. The higher the temperature index (TS) value of the sample, the better the thermal stability of the material. The calculation formula is as follows: TS = 0.49 × (0.4T5% + 0.6T30%); Antibacterial performance: According to JC / T 2930-2010 standard, the number of samples is 18 pieces and the sample shape is sheet.

[0047] The performance test results are shown in the following table:

[0048] As can be seen from Table 1, the tensile strength, tensile modulus, impact strength, flexural strength and flexural modulus of Examples 1 to 3 are all greater than those of Comparative Example 1, Comparative Example 3 and Comparative Example 4. In step S5 of Comparative Example 1, the composite basalt fiber aerogel is removed. In step S1, Comparative Example 3 does not go through step S1, and basalt fiber is used instead of surface-etched basalt fiber in step S3. In step S5, Comparative Example 4 does not go through step S4, and polylactic acid pellets are used instead of stereocomposite polylactic acid fiber in step S5. This shows that surface-etched basalt fiber and stereocomposite polylactic acid fiber can improve the mechanical properties of polylactic acid-based fully degradable and environmentally friendly furniture panels. This may be because the increase in the roughness of the surface-etched basalt fiber improves the bonding force, and the stereocomposite homogeneous crystals of the stereocomposite polylactic acid fiber are more stable, so the mechanical properties are improved.

[0049] The TS in Examples 1 to 3 are all greater than those in Comparative Example 1 and Comparative Example 4. The composite basalt fiber aerogel is removed in step S5 of Comparative Example 1, and step S4 is not performed in Comparative Example 4. In step S5, polylactic acid pellets are used instead of stereocomposite polylactic acid fibers. This may be because the structure of the stereocomposite homogeneous crystals in the stereocomposite polylactic acid fibers is more stable at high temperatures, and the structure formed by the composite basalt fiber aerogel can further fill the pores of the stereocomposite polylactic acid fibers, thereby inhibiting the thermal motion of the molecular chain segments of the stereocomposite polylactic acid fibers, thereby improving the heat resistance of the polylactic acid-based fully degradable and environmentally friendly furniture panels.

[0050] The anti-Escherichia coli rate and the anti-Staphylococcus aureus rate in Examples 1 to 3 are greater than those in Comparative Example 1, Comparative Example 2, and Comparative Example 3. In step S5 of Comparative Example 1, the composite basalt fiber aerogel is removed, and in step S2 of Comparative Example 2, the chitosan glacial acetic acid solution is removed to prepare a single sol precursor solution, and the prepared single sol precursor solution is used to replace the composite precursor solution in step S3. Comparative Example 3 does not go through step S1, and in step S3, basalt fiber is used instead of surface-etched basalt fiber. This may be because the increase in the roughness of the surface-etched basalt fiber provides more attachment sites for the aerogel sol, which can make chitosan evenly adhere to the surface of the surface-etched basalt fiber, and chitosan itself has a certain antibacterial effect, which improves the antibacterial properties of the polylactic acid-based fully degradable and environmentally friendly furniture board.

[0051] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a polylactic acid-based fully degradable environmentally friendly furniture board, characterized in that: The steps include: Step 1: etching the surface of the basalt fiber by plasma treatment to obtain surface-etched basalt fiber; Step 2: Using tetraethyl orthosilicate as a silicon source to generate silicon dioxide and compounding it with chitosan to obtain a composite sol precursor solution, and mixing the composite precursor solution with surface-etched basalt fiber to obtain a composite basalt fiber aerogel; Step 3: combining poly (L-lactic acid) powder, poly (D-lactic acid) powder and poly (butylene adipate / terephthalate) powder by melt blending to obtain stereocomposite poly (lactic acid) fiber; Step 4: Add the stereocomposite polylactic acid fiber, composite basalt fiber aerogel, and bamboo fiber into the torque rheometer, perform internal mixing, and perform compression molding to obtain polylactic acid-based fully biodegradable and environmentally friendly furniture panels.

2. The method for preparing the polylactic acid-based fully degradable environmentally friendly furniture board according to claim 1, characterized in that: The preparation process of the surface-etched basalt fiber described in step 1 is as follows: The basalt fiber and acetone solution are added to a reactor, ultrasonically cleaned, washed, and dried, and then placed in a quartz tube of a low-temperature plasma generator. Vacuuming is started in a sealed state, and oxygen is supplied under the conditions of 35-50 Pa and 15-20 r / min. After plasma treatment, the equipment is closed, cooled to room temperature, and the vacuum degree is restored to atmospheric pressure to obtain surface-etched basalt fiber.

3. The method for preparing the polylactic acid-based fully degradable environmentally friendly furniture board according to claim 2, characterized in that: The plasma treatment has a discharge power of 120-130 W, a discharge time of 200-320 s, and an oxygen flow rate of 20-30 mL / min.

4. The method for preparing the polylactic acid-based fully degradable environmentally friendly furniture board according to claim 1, characterized in that: The preparation process of the composite sol precursor solution in step 2 is as follows: Adding tetraethyl orthosilicate, anhydrous ethanol and deionized water into a reactor, adjusting the pH value to 2-3 with hydrochloric acid, hydrolyzing at 30-40°C and 500-600 r / min for 12-14 hours, adding 3wt% chitosan glacial acetic acid solution, stirring at 23-25°C for 5-7 minutes, to obtain a composite sol precursor solution; The usage ratio of the tetraethyl orthosilicate, anhydrous ethanol, deionized water and chitosan glacial acetic acid solution is 270-300 g: 630-700 mL: 100-120 mL: 200-300 mL.

5. The method for preparing the polylactic acid-based fully degradable environmentally friendly furniture board according to claim 1, characterized in that: The preparation process of the composite basalt fiber aerogel in step 2 is as follows: The composite precursor solution and the surface-etched basalt fiber are added to a reactor, aged at 20-25° C. for 48-50 hours, filtered, and the precipitate, trimethylchlorosilane, and anhydrous ethanol are added to the reactor, soaked for 12-14 hours, washed, extracted with supercritical carbon dioxide at 50-60° C. and 12-13 MPa for 12-14 hours, cooled, and decompressed to obtain a composite basalt fiber aerogel. The ratio of the composite precursor solution to the surface-etched basalt fiber is 500-600 mL: 50-60 g; The usage ratio of the precipitate, trimethylchlorosilane and anhydrous ethanol is 50-60 g: 10-15 mL: 90-100 mL.

6. The method for preparing the polylactic acid-based fully degradable environmentally friendly furniture board according to claim 1, characterized in that: The preparation process of the stereocomposite polylactic acid fiber in step 3 is as follows: Poly (L-lactic acid) powder, poly (D-lactic acid) powder and poly (butylene adipate) terephthalate powder are mixed evenly, and the mixed powder is fed into a single-screw extruder with a melting temperature of 185-195°C and a screw speed of 120-150 r / min. The melt is directed to a winding drum with a speed of 250-300 r / min to obtain spun fibers. The spun fibers are drawn at 120-140°C with a drawing ratio of 3. The drawn fibers are annealed at 160-200°C for 20-30 minutes with a tension of 10-12 MPa to obtain stereocomposite polylactic acid fibers.

7. The method for preparing the polylactic acid-based fully degradable environmentally friendly furniture board according to claim 6, characterized in that: The mass ratio of the poly (L-lactic acid) powder, the poly (D-lactic acid) powder and the poly (adipate / butylene terephthalate) powder is 50-70:50-70:5-6.

8. The method for preparing the polylactic acid-based fully degradable and environmentally friendly furniture board according to claim 1, characterized in that: The preparation process of the polylactic acid-based fully degradable environmentally friendly furniture board described in step 4 is as follows: The stereocomposite polylactic acid fiber, the composite basalt fiber aerogel and the bamboo fiber with a length of 20-30 mm were added to the torque rheometer, mixed for 8-10 minutes, and then compression molded using a flat vulcanizer with a molding time of 300-320 seconds and a cooling time of 300-320 seconds to obtain a polylactic acid-based fully biodegradable environmentally friendly furniture board. The mass ratio of the stereocomposite polylactic acid fiber, the composite basalt fiber aerogel and the bamboo fiber is 80-100:20-30:20-30.

9. The method for preparing the polylactic acid-based fully degradable and environmentally friendly furniture board according to claim 8, characterized in that: The temperature of the banburying treatment is 170-180°C and the rotation speed is 30-60r / min; The molding temperature is 190-200° C., the molding pressure is 10-15 MPa, the exhaust stroke is 5-6 cm, and the exhaust times are 30-40 times.

10. A polylactic acid-based fully biodegradable environmentally friendly furniture board, characterized in that: The invention is prepared by the preparation method of the polylactic acid-based fully degradable environmentally friendly furniture board according to any one of claims 1 to 9.

Images