A bio-based foaming material and its preparation method

Abstract

The present invention discloses a bio-based foaming material and a preparation method thereof, relating to the technical field of foaming materials. When preparing the bio-based foaming material of the present invention, (1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde are reacted to prepare a spiropyran ultraviolet absorber; the spiropyran ultraviolet absorber and ethylene-vinyl acetate copolymer are reacted to prepare a modified ethylene-vinyl acetate copolymer; 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine are polymerized and grown on pre-modified nano-silica to prepare modified nano-silica; the modified ethylene-vinyl acetate copolymer, styrene-butadiene block copolymer, modified nano-silica, and phytic acid are mixed and granulated, and supercritical foaming is carried out to prepare the bio-based foaming material. The bio-based foaming material prepared by the present invention has excellent anti-aging, flame retardant, antibacterial, and wear-resistant properties.

Description

Technical Field

[0001] The present invention relates to the technical field of foaming materials, and particularly to a bio-based foaming material and a preparation method thereof. Background Art

[0002] In modern society, people's persistent pursuit of a better life has led to a great change in the concept of wearing shoes. From the protection and heat preservation in the last century to the pursuit of functions such as comfort, lightness, beauty, and shock absorption now. Traditional shoe materials are generally high-molecular materials such as animal leather, natural rubber, and polyvinyl chloride. The shoes made therefrom have problems such as being heavy, airtight, easy to wear, and poor comfort, and it is difficult to meet people's needs for functional shoe materials. Moreover, when doing a lot of exercise or working and living in a humid and stuffy environment, the sweat secreted by the human foot provides a favorable environment for the growth of microorganisms, affecting people's health. These series of problems have prompted shoe-making enterprises to actively seek innovation and develop new shoe materials that meet market demands.

[0003] Based on the existing technical problems, the present application proposes a bio-based foaming material and a preparation method thereof, and prepares a bio-based foaming material with excellent antibacterial and wear-resistant properties as a new shoe material to improve wearing comfort and meet the market's demand for functional shoe materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a bio-based foaming material and a preparation method thereof to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A bio-based foaming material, wherein the bio-based foaming material is prepared by reacting a spiropyran ultraviolet absorber and ethylene-vinyl acetate copolymer to obtain a modified ethylene-vinyl acetate copolymer; polymerizing and growing 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine on pre-modified nano-silica to obtain modified nano-silica; mixing and granulating the modified ethylene-vinyl acetate copolymer, styrene-butadiene block copolymer, modified nano-silica, and phytic acid, and performing supercritical foaming.

[0007] The spiropyran ultraviolet absorber is prepared by reacting (1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde.

[0008] The pre-modified nano-silica is prepared by reacting nano-silica and 3-aminopropyltriethoxysilane.

[0009] A preparation method of a bio-based foaming material, wherein the preparation method of the bio-based foaming material comprises the following preparation steps:

[0010] (1) Mix the spiropyran ultraviolet absorber, diisopropylbenzene peroxide, and acetone evenly at a mass ratio of 1:(0.1 - 0.12):(3 - 4), stir at 10 - 30 °C and 300 - 500 r / min for 3 - 5 min, add ethylene-vinyl acetate copolymer which is 45 - 55 times the mass of the spiropyran ultraviolet absorber, continue to stir for 10 - 12 min, let stand for 11 - 13 h, place it in a plastifying instrument for melt plastification, set the plastifying temperature at 170 - 180 °C, the screw speed at 40 - 50 r / min, and the plastifying time at 10 - 12 min, dry at 50 - 60 °C under vacuum conditions for 3 - 4 h to obtain the modified ethylene-vinyl acetate copolymer;

[0011] (2) Add the pre-modified nano-silica, 1,3-diaminoguanidine hydrochloride, and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine to the reaction kettle at a mass ratio of 1:(0.4 - 0.6):(0.3 - 0.5), stir and react at 160 - 180 °C and 400 - 600 r / min for 3 - 4 h, cool down to 70 - 80 °C, continue to stir and react for 1 - 2 h, wash with anhydrous ethanol and deionized water 3 - 5 times each, dry at 50 - 60 °C under vacuum conditions for 7 - 8 h to obtain the modified nano-silica;

[0012] (3) Weigh 30 - 40 parts of the modified ethylene-vinyl acetate copolymer, 10 - 20 parts of styrene-butadiene block copolymer, 1 - 2 parts of the modified nano-silica, and 1 - 1.5 parts of zinc stearate by mass, mix them evenly, place them in a twin-screw extruder for mixing and pelletizing to obtain the mixed masterbatch; Mix the mixed masterbatch, phytic acid, and di-tert-butyl peroxyisopropylbenzene at a mass ratio of 1:(0.06 - 0.08):(0.03 - 0.04), place them in a kneader, knead at 150 - 160 °C and 300 - 500 r / min for 10 - 20 min under stirring conditions, then place them on an open mill, thin pass 6 - 8 times at 150 - 160 °C, place them on a flat vulcanizing machine to press into a plate, then place them in a high-pressure foaming kettle, use nitrogen as the foaming agent for supercritical foaming, set the pressure of the high-pressure foaming kettle at 24 - 28 MPa, the temperature at 175 - 185 °C, release the pressure after 1 - 2 h, the pressure release time is 15 - 25 s, cool to room temperature to obtain the bio-based foamed material.

[0013] As an optimization, the preparation method of the spiropyran ultraviolet absorber in step (1) is as follows: (1,3,3-Trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde are added to methanol at 14 to 16 times the mass of 3-allylsalicylaldehyde at a molar ratio of 1:1. Under a nitrogen atmosphere, at 65 to 75 °C and 300 to 500 r / min, stir and reflux for 2 to 3 h. Under vacuum conditions, dry at 50 to 60 °C for 7 to 9 h to obtain the spiropyran ultraviolet absorber.

[0014] As an optimization, the model of the ethylene-vinyl acetate copolymer in step (1) is Y2045 18-3.

[0015] As an optimization, the preparation method of the pre-modified nano-silica in step (2) is as follows: Mix nano-silica and absolute ethanol evenly at a mass ratio of 1:(20 to 30), add a silane hydrolysis solution at 8 to 10 times the mass of nano-silica. At 50 to 60 °C and 300 to 500 r / min, stir and react for 2 to 3 h, filter, wash with absolute ethanol 3 to 5 times, and dry at 70 to 80 °C for 8 to 10 h under vacuum conditions to obtain the pre-modified nano-silica.

[0016] As an optimization, the preparation method of the silane hydrolysis solution is as follows: Mix 3-aminopropyltriethoxysilane and absolute ethanol evenly at a mass ratio of 1:(40 to 50), adjust the pH to 4 to 6 with a 1 mol / L oxalic acid aqueous solution, and stir at 10 to 30 °C and 300 to 500 r / min for 50 to 60 min to prepare the silane hydrolysis solution.

[0017] As an optimization, the model of the styrene-butadiene block copolymer in step (3) is: HJ15A.

[0018] As an optimization, the process parameters of the twin-screw extruder in step (3) are: Set the temperature of the twin-screw extruder to 170 to 180 °C and the screw speed to 90 to 100 r / min.

[0019] As an optimization, the process parameters of the flat vulcanizer in step (3) are: Set the temperature of the flat vulcanizer to 140 to 150 °C, the pressure to 14 to 16 MPa, and the time to 8 to 10 min.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] When preparing the bio-based foaming material of the present invention, (1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde are reacted to obtain a spiropyran ultraviolet absorber; the spiropyran ultraviolet absorber and ethylene-vinyl acetate copolymer are reacted to obtain a modified ethylene-vinyl acetate copolymer; nano-silica and 3-aminopropyltriethoxysilane are reacted to obtain pre-modified nano-silica; 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine are polymerized and grown on the pre-modified nano-silica to obtain modified nano-silica; the modified ethylene-vinyl acetate copolymer, styrene-butadiene block copolymer, modified nano-silica and phytic acid are mixed and granulated, and supercritical foaming is carried out to obtain the bio-based foaming material.

[0022] First, (1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde are reacted to obtain a spiropyran ultraviolet absorber, and carbon-carbon double bonds and hydroxymethyl groups are introduced onto the spiropyran ultraviolet absorber; the spiropyran ultraviolet absorber is composed of two aromatic rings connected by a sp3 hybridized spiro carbon atom, which are orthogonal to each other and do not produce molecular structural conjugation, forming a closed-loop body. After being excited by ultraviolet light, the spiro-oxygen bond in the molecule undergoes heterolytic cleavage and the electronic configuration undergoes isomerization or rearrangement, becoming an open-loop body with a coplanar structure of two ring systems. The whole molecule forms a large conjugated plane. The open-loop body can be re-closed to form a closed-loop body under visible light irradiation or heating, thereby endowing the bio-based foaming material with excellent anti-ultraviolet aging performance; the carbon-carbon double bonds in the spiropyran ultraviolet absorber are melt-grafted onto the side chains of the ethylene-vinyl acetate copolymer to obtain a modified ethylene-vinyl acetate copolymer, and hydroxymethyl groups are introduced onto the side chains of the modified ethylene-vinyl acetate copolymer. The hydroxymethyl groups can dehydrate with the phosphate groups on phytic acid under high temperature and high pressure to form a cross-linked network, inhibiting the relative slippage of molecular chains, making the finally formed cell structure stable, and at the same time improving the mechanical properties of the bio-based foaming material. The molecular chains are not easily torn by external shear forces, enhancing the wear resistance.

[0023] Secondly, nano-silica and 3-aminopropyltriethoxysilane are reacted to obtain pre-modified nano-silica, and amino groups are introduced onto the pre-modified nano-silica. 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine are polymerized and grown on the pre-modified nano-silica to obtain modified nano-silica. 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine undergo thermal polycondensation with the elimination of ammonia gas at high temperature, introducing guanidinium salt structure, triazine structure, fluorine atoms and amino groups onto the modified nano-silica. The introduction of the guanidinium salt structure can endow the bio-based foaming material with excellent antibacterial properties. The triazine structure can generate non-combustible nitrogen-containing gases, absorb heat and dilute the oxygen concentration, improving the flame retardancy of the bio-based foaming material. Fluorine atoms have low reactivity, are hydrophobic and oleophobic, and can enhance the anti-fouling and corrosion resistance of the bio-based foaming material. The amino groups on the modified nano-silica can also dehydrate with the phosphate groups on phytic acid under high temperature and high pressure to form a crosslinked network, inhibiting the relative slippage of molecular chains, making the finally formed cell structure stable, and at the same time improving the mechanical properties of the bio-based foaming material. The molecular chains are not easily torn by external shear forces, enhancing the wear resistance. Nano-silica has a high specific surface area and excellent mechanical properties, which can improve the strength and hardness of the matrix resin. Modifying the nano-silica can increase the compatibility between the nano-silica and the matrix resin, reduce the agglomeration phenomenon of the nano-silica, make the nano-silica uniformly dispersed in the matrix resin, and fully exert the reinforcing effect of the nano-silica, further improving the wear resistance of the bio-based foaming material.

[0024] Finally, the modified ethylene-vinyl acetate copolymer, styrene-butadiene block copolymer, modified nano-silica and phytic acid are mixed and granulated, and bio-based foaming material is prepared by supercritical foaming; phytic acid is an organic phosphorus compound extracted from plant seeds, containing a large amount of phosphorus elements and phosphate groups. The introduction of phytic acid can not only further improve the flame retardancy of the bio-based foaming material, but also the phosphate groups in phytic acid can dehydrate with the hydroxymethyl groups on the modified ethylene-vinyl acetate copolymer and the amino groups on the modified nano-silica under high temperature and high pressure to form a crosslinked network, inhibiting the relative slippage of molecular chains, making the finally formed cell structure stable, and at the same time improving the mechanical properties of the bio-based foaming material. The molecular chains are not easily torn by external shear forces, enhancing the wear resistance. Specific embodiments

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Example 1

[0027] A preparation method of a bio-based foaming material, the preparation method of the bio-based foaming material comprising the following preparation steps:

[0028] (1) (1,3,3-Trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde are added to methanol 14 times the mass of 3-allylsalicylaldehyde at a molar ratio of 1:1. Under a nitrogen atmosphere, it is stirred and refluxed at 65 °C and 300 r / min for 3 h, and dried at 50 °C for 9 h under vacuum conditions to obtain a spiropyran ultraviolet absorber; the spiropyran ultraviolet absorber, diisopropylbenzene peroxide, and acetone are mixed evenly at a mass ratio of 1:0.1:3, stirred at 10 °C and 300 r / min for 5 min, ethylene-vinyl acetate copolymer 45 times the mass of the spiropyran ultraviolet absorber is added, and stirring is continued for 12 min, left standing for 13 h, and placed in a plastifying instrument for melt plastification. The plastifying temperature is set at 170 °C, the screw speed is 40 r / min, and the plastifying time is 12 min. It is dried at 50 °C for 4 h under vacuum conditions to obtain a modified ethylene-vinyl acetate copolymer;

[0029] (2) 3-aminopropyltriethoxysilane and absolute ethanol are mixed evenly at a mass ratio of 1:40, and the pH is adjusted to 4 with a 1 mol / L oxalic acid aqueous solution. It is stirred at 10 °C and 300 r / min for 60 min to prepare a silane hydrolysis solution; nano-silica and absolute ethanol are mixed evenly at a mass ratio of 1:20, and the silane hydrolysis solution 8 times the mass of the nano-silica is added. It is stirred and reacted at 50 °C and 300 r / min for 3 h, filtered, washed 3 times with absolute ethanol, and dried at 70 °C for 10 h under vacuum conditions to obtain pre-modified nano-silica; the pre-modified nano-silica, 1,3-diaminoguanidine hydrochloride, and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine are added to the reaction kettle at a mass ratio of 1:0.4:0.3, stirred and reacted at 160 °C and 400 r / min for 4 h, cooled to 70 °C, and stirring reaction is continued for 2 h. It is washed 3 times each with absolute ethanol and deionized water, and dried at 50 °C for 8 h under vacuum conditions to obtain modified nano-silica;

[0030] (3) Weigh 30 parts of modified ethylene-vinyl acetate copolymer, 10 parts of styrene-butadiene block copolymer, 1 part of modified nano-silica, and 1 part of zinc stearate by mass fraction, mix them evenly, place them in a twin-screw extruder for mixing and granulation. Set the temperature of the twin-screw extruder to 170 °C and the screw speed to 90 r / min to obtain a mixed masterbatch. Mix the mixed masterbatch, phytic acid, and di-tert-butyl peroxyisopropylbenzene in a mass ratio of 1:0.06:0.03, place them in a Banbury mixer, and knead them for 20 min under stirring conditions of 150 °C and 300 r / min. Then place them in an open mill and thin pass them 8 times at 150 °C. Place them on a flat vulcanizing machine and press them into a plate. Set the temperature of the flat vulcanizing machine to 140 °C, the pressure to 14 MPa, and the time to 10 min. Then place them in a high-pressure foaming kettle and use nitrogen as a foaming agent for supercritical foaming. Set the pressure of the high-pressure foaming kettle to 24 MPa and the temperature to 175 °C. After 2 h, relieve the pressure, and the pressure relief time is 15 s. Cool to room temperature to obtain a bio-based foamed material.

[0031] Example 2

[0032] A preparation method of a bio-based foamed material, the preparation method of the bio-based foamed material includes the following preparation steps:

[0033] (1) Add (1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde in a molar ratio of 1:1 to methanol that is 15 times the mass of 3-allylsalicylaldehyde. Under a nitrogen atmosphere, stir and reflux at 70 °C and 400 r / min for 2.5 h. Under vacuum conditions, dry at 55 °C for 8 h to obtain a spiropyran ultraviolet absorber. Mix the spiropyran ultraviolet absorber, diisopropylbenzene peroxide, and acetone evenly in a mass ratio of 1:0.11:3.5, stir at 20 °C and 400 r / min for 4 min, add an ethylene-vinyl acetate copolymer that is 50 times the mass of the spiropyran ultraviolet absorber, continue to stir for 11 min, let it stand for 12 h, place it in a plastifying instrument for melting and plastifying. Set the plastifying temperature to 175 °C, the screw speed to 45 r / min, and the plastifying time to 11 min. Dry at 55 °C for 3.5 h under vacuum conditions to obtain a modified ethylene-vinyl acetate copolymer;

[0034] (2) Mix 3-aminopropyltriethoxysilane and absolute ethanol evenly according to a mass ratio of 1:45, adjust the pH to 5 with 1 mol / L oxalic acid aqueous solution, stir at 20 °C and 400 r / min for 55 min to prepare a silane hydrolysis solution; mix nano-silica and absolute ethanol evenly according to a mass ratio of 1:25, add a silane hydrolysis solution 9 times the mass of nano-silica, stir and react at 55 °C and 400 r / min for 2.5 h, filter, wash 4 times with absolute ethanol, and dry at 75 °C for 9 h under vacuum conditions to obtain pre-modified nano-silica; add pre-modified nano-silica, 1,3-diaminoguanidine hydrochloride, and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine into a reaction kettle according to a mass ratio of 1:0.5:0.4, stir and react at 170 °C and 500 r / min for 3.5 h, cool down to 75 °C, continue to stir and react for 1.5 h, wash 4 times with absolute ethanol and deionized water respectively, and dry at 55 °C for 7.5 h under vacuum conditions to obtain modified nano-silica;

[0035] (3) Weigh 35 parts of modified ethylene-vinyl acetate copolymer, 15 parts of styrene-butadiene block copolymer, 1.5 parts of modified nano-silica, and 1.25 parts of zinc stearate according to mass parts, mix them evenly, and place them in a twin-screw extruder for mixing and pelletizing. Set the temperature of the twin-screw extruder to 175 °C and the screw speed to 95 r / min to obtain a mixed masterbatch; mix the mixed masterbatch, phytic acid, and di-tert-butyl peroxyisopropylbenzene according to a mass ratio of 1:0.07:0.035, place them in a kneader, knead at 155 °C and 400 r / min for 15 min, then place them in an open mill, thin-pass 7 times at 155 °C, place them on a flat vulcanizer to press into a plate, set the temperature of the flat vulcanizer to 145 °C, the pressure to 15 MPa, and the time to 9 min, then place them in a high-pressure foaming kettle, use nitrogen as a foaming agent for supercritical foaming, set the pressure of the high-pressure foaming kettle to 26 MPa, the temperature to 180 °C, release the pressure after 1.5 h, the pressure release time is 20 s, and cool to room temperature to obtain a bio-based foamed material.

[0036] Example 3

[0037] A preparation method of a bio-based foamed material, the preparation method of the bio-based foamed material includes the following preparation steps:

[0038] (1) (1,3,3-Trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde were added to methanol in a mass ratio of 16 times that of 3-allylsalicylaldehyde at a molar ratio of 1:1. Under a nitrogen atmosphere, the mixture was stirred and refluxed at 75 °C and 500 r / min for 2 h, and then dried at 60 °C under vacuum for 7 h to obtain a spiropyran ultraviolet absorber. The spiropyran ultraviolet absorber, diisopropylbenzene peroxide, and acetone were mixed evenly at a mass ratio of 1:0.12:4, stirred at 30 °C and 500 r / min for 3 min, then ethylene-vinyl acetate copolymer 55 times the mass of the spiropyran ultraviolet absorber was added, and stirring was continued for 10 min. After standing for 11 h, it was placed in a plastifying instrument for melt plastification. The plastifying temperature was set at 180 °C, the screw speed was 50 r / min, and the plastifying time was 10 min. It was dried at 60 °C under vacuum for 3 h to obtain a modified ethylene-vinyl acetate copolymer;

[0039] (2) 3-Aminopropyltriethoxysilane and absolute ethanol were mixed evenly at a mass ratio of 1:50, and the pH was adjusted to 6 with 1 mol / L oxalic acid aqueous solution. The mixture was stirred at 30 °C and 500 r / min for 50 min to prepare a silane hydrolysis solution. Nanometer silicon dioxide and absolute ethanol were mixed evenly at a mass ratio of 1:30, and then the silane hydrolysis solution 10 times the mass of the nanometer silicon dioxide was added. The mixture was stirred and reacted at 60 °C and 500 r / min for 2 h, filtered, washed 5 times with absolute ethanol, and dried at 80 °C under vacuum for 8 h to obtain pre-modified nanometer silicon dioxide. The pre-modified nanometer silicon dioxide, 1,3-diaminoguanidine hydrochloride, and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine were added to a reaction kettle at a mass ratio of 1:0.6:0.5, stirred and reacted at 180 °C and 600 r / min for 3 h, cooled to 80 °C, and stirring was continued for 1 h. It was washed 5 times each with absolute ethanol and deionized water, and dried at 60 °C under vacuum for 7 h to obtain modified nanometer silicon dioxide;

[0040] (3) Weigh 40 parts by mass of modified ethylene-vinyl acetate copolymer, 20 parts of styrene-butadiene block copolymer, 2 parts of modified nano-silica, and 1.5 parts of zinc stearate, mix them evenly, place them in a twin-screw extruder for mixing and pelletizing. Set the temperature of the twin-screw extruder to 180 °C and the screw speed to 100 r / min to obtain a mixed masterbatch; mix the mixed masterbatch, phytic acid, and di-tert-butyl peroxyisopropylbenzene in a mass ratio of 1:0.08:0.04, place them in a kneader, knead for 10 min under stirring conditions of 160 °C and 500 r / min, then place them in an open mill and thin-pass 6 times at 160 °C, place them on a flat vulcanizing machine to press into a plate. Set the temperature of the flat vulcanizing machine to 150 °C, the pressure to 16 MPa, and the time to 8 min. Then place it in a high-pressure foaming kettle and use nitrogen as a foaming agent for supercritical foaming. Set the pressure of the high-pressure foaming kettle to 28 MPa, the temperature to 185 °C, release the pressure after 1 h, the pressure release time is 25 s, and cool to room temperature to obtain a bio-based foamed material.

[0041] Comparative Example 1

[0042] The preparation method of the bio-based foamed material in Comparative Example 1 is different from that in Example 2 in that step (1) is not carried out, and step (3) is modified as follows: Weigh 35 parts by mass of ethylene-vinyl acetate copolymer, 15 parts of styrene-butadiene block copolymer, 1.5 parts of modified nano-silica, and 1.25 parts of zinc stearate, mix them evenly, place them in a twin-screw extruder for mixing and pelletizing. Set the temperature of the twin-screw extruder to 175 °C and the screw speed to 95 r / min to obtain a mixed masterbatch; mix the mixed masterbatch, phytic acid, and di-tert-butyl peroxyisopropylbenzene in a mass ratio of 1:0.07:0.035, place them in a kneader, knead for 15 min under stirring conditions of 155 °C and 400 r / min, then place them in an open mill and thin-pass 7 times at 155 °C, place them on a flat vulcanizing machine to press into a plate. Set the temperature of the flat vulcanizing machine to 145 °C, the pressure to 15 MPa, and the time to 9 min. Then place it in a high-pressure foaming kettle and use nitrogen as a foaming agent for supercritical foaming. Set the pressure of the high-pressure foaming kettle to 26 MPa, the temperature to 180 °C, release the pressure after 1.5 h, the pressure release time is 20 s, and cool to room temperature to obtain a bio-based foamed material. The remaining steps are the same as those in Example 2.

[0043] Comparative Example 2

[0044] The preparation method of the bio-based foamed material of Comparative Example 2 is different from that of Example 2 in that step (2) is not carried out, and step (3) is modified as follows: by mass, 35 parts of modified ethylene-vinyl acetate copolymer, 15 parts of styrene-butadiene block copolymer, 1.5 parts of nano-silica, and 1.25 parts of zinc stearate are weighed and mixed evenly, placed in a twin-screw extruder for mixing and granulation, the temperature of the twin-screw extruder is set at 175 °C, and the screw speed is 95 r / min to obtain a mixed masterbatch; the mixed masterbatch, phytic acid, and di-tert-butyl peroxyisopropylbenzene are mixed in a mass ratio of 1:0.07:0.035, placed in a kneader, kneaded for 15 min under stirring conditions of 155 °C and 400 r / min, then placed in an open mill and passed through thinly 7 times at 155 °C, placed on a flat vulcanizing machine to be pressed into a plate, the temperature of the flat vulcanizing machine is set at 145 °C, the pressure is 15 MPa, and the time is 9 min, then placed in a high-pressure foaming kettle, and supercritical foaming is carried out using nitrogen as a foaming agent, the pressure of the high-pressure foaming kettle is set at 26 MPa, the temperature is 180 °C, the pressure is relieved after 1.5 h, the pressure relief time is 20 s, and it is cooled to room temperature to obtain the bio-based foamed material. The remaining steps are the same as those in Example 2.

[0045] Comparative Example 3

[0046] The preparation method of the bio-based foamed material of Comparative Example 3 is different from that of Example 2 only in step (3), and step (3) is modified as follows: by mass, 35 parts of modified ethylene-vinyl acetate copolymer, 15 parts of styrene-butadiene block copolymer, 1.5 parts of modified nano-silica, and 1.25 parts of zinc stearate are weighed and mixed evenly, placed in a twin-screw extruder for mixing and granulation, the temperature of the twin-screw extruder is set at 175 °C, and the screw speed is 95 r / min to obtain a mixed masterbatch; the mixed masterbatch and di-tert-butyl peroxyisopropylbenzene are mixed in a mass ratio of 1:0.035, placed in a kneader, kneaded for 15 min under stirring conditions of 155 °C and 400 r / min, then placed in an open mill and passed through thinly 7 times at 155 °C, placed on a flat vulcanizing machine to be pressed into a plate, the temperature of the flat vulcanizing machine is set at 145 °C, the pressure is 15 MPa, and the time is 9 min, then placed in a high-pressure foaming kettle, and supercritical foaming is carried out using nitrogen as a foaming agent, the pressure of the high-pressure foaming kettle is set at 26 MPa, the temperature is 180 °C, the pressure is relieved after 1.5 h, the pressure relief time is 20 s, and it is cooled to room temperature to obtain the bio-based foamed material. The remaining steps are the same as those in Example 2.

[0047] Test Example 1

[0048] Test of flame retardancy performance

[0049] Test method: The limiting oxygen index of the examples and comparative examples was tested according to GB / T 2406.1. The results are shown in Table 1.

[0050] Table 1

[0051] Limiting oxygen index (%) Limiting oxygen index (%) Example 1 30.79 Comparative Example 1 30.18 Example 2 31.25 Comparative Example 2 26.73 Example 3 30.61 Comparative Example 3 24.59

[0052] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the bio-based foaming material prepared by the present invention has good flame retardant properties.

[0053] By comparison, the limiting oxygen index of Examples 1 to 3 is greater than that of Comparative Example 2, indicating that pre-modified nano-silica is prepared by reacting nano-silica and 3-aminopropyltriethoxysilane, amino groups are introduced onto the pre-modified nano-silica, 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine are polymerized and grown on the pre-modified nano-silica to obtain modified nano-silica, 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine undergo thermal polycondensation with the elimination of ammonia gas at high temperature, and triazine structures are introduced onto the modified nano-silica. The triazine structures can generate non-combustible nitrogen-containing gases, absorb heat, dilute the oxygen concentration, and improve the flame retardant properties of the bio-based foaming material.

[0054] By comparison, the limiting oxygen index of Examples 1 to 3 is greater than that of Comparative Example 3, indicating that a bio-based foaming material is prepared by mixing and granulating modified ethylene-vinyl acetate copolymer, styrene-butadiene block copolymer, modified nano-silica, and phytic acid and then performing supercritical foaming; phytic acid is an organic phosphorus compound extracted from plant seeds and contains a large amount of phosphorus elements. The introduction of phytic acid can further improve the flame retardant properties of the bio-based foaming material.

[0055] Test Example 2

[0056] Test of antibacterial properties

[0057] Test method: Cut the samples of the examples and comparative examples into 1 cm x 1 cm pieces, wash them with ethanol and set aside; activate the Escherichia coli strain and prepare a bacterial suspension with a concentration of 2 x 104 cfu / ml. Then put the cut samples into the bacterial suspension, fix the Erlenmeyer flask containing the bacterial suspension and the samples on an oscillating shaker, and shake at a speed of 300 r / min at a temperature of 20 °C for 2 min. Dilute 1.0 ml of the bacterial suspension to 100 times, pipette 1.0 ml of the shaken sample solution, inoculate it on the agar medium, and culture it at 37 °C for 48 h under natural light. Perform colony counting according to the method in GB15979-2003. Calculate the antibacterial rate according to the following formula: antibacterial rate = (average colony count before sample oscillation - average colony count after sample oscillation) / average colony count before sample oscillation x 100%. The results are shown in Table 2.

[0058] Table 2

[0059] Bacteriostatic rate (%) Bacteriostatic rate (%) Example 1 99.73 Comparative Example 1 99.64 Example 2 99.83 Comparative Example 2 71.12 Example 3 99.68 Comparative Example 3 99.58

[0060] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 2, it can be found that the bio-based foaming material prepared by the present invention has good antibacterial properties.

[0061] By comparison, the antibacterial rates of Examples 1 to 3 are greater than that of Comparative Example 2, indicating that pre-modified nano-silica is prepared by reacting nano-silica with 3-aminopropyltriethoxysilane, amino groups are introduced onto the pre-modified nano-silica, 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine are polymerized and grown on the pre-modified nano-silica to obtain modified nano-silica, 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine undergo thermal condensation by removing ammonia gas at high temperature, and guanidine salt structures are introduced onto the modified nano-silica. The introduction of guanidine salt structures can endow the bio-based foaming material with excellent antibacterial properties.

[0062] Test Example 3

[0063] Test of anti-aging performance

[0064] Test method: According to GB / T 6344, the examples and comparative examples are prepared into standard specimens, and the tensile strength of the standard specimens is tested. The standard specimens are irradiated with a xenon arc lamp for 72 h, and then the tensile strength of the standard specimens after ultraviolet aging treatment is tested by the same method. The change rate of the tensile strength of the examples and comparative examples before and after ultraviolet aging treatment is calculated. The change rate of tensile strength = (tensile strength of the standard specimen - tensile strength of the standard specimen after ultraviolet aging treatment) / tensile strength of the standard specimen × 100%. The results are shown in Table 3.

[0065] Table 3

[0066]

[0067] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 3, it can be found that the bio-based foaming material prepared by the present invention has good anti-aging performance.

[0068] By comparison, the change rate of the tensile strength in Examples 1 to 3 is less than that in Comparative Example 1, indicating that the spiropyran ultraviolet absorber is prepared by reacting (1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol with 3-allylsalicylaldehyde, and a carbon-carbon double bond and a hydroxymethyl group are introduced onto the spiropyran ultraviolet absorber; the spiropyran ultraviolet absorber is formed by two aromatic rings connected by a sp3 hybridized spiro carbon atom that are orthogonal to each other, without generating molecular structural conjugation, forming a closed-loop body. After being excited by ultraviolet light, the spiro-oxygen bond in the molecule undergoes heterolytic cleavage and the electronic configuration undergoes isomerization or rearrangement, becoming an open-loop body with a coplanar structure of two ring systems. The whole molecule forms a large conjugated plane, and the open-loop body can be re-closed to form a closed-loop body under visible light irradiation or heating, thereby endowing the bio-based foaming material with excellent anti-aging properties.

[0069] Test Example 4

[0070] Test of wear resistance

[0071] Test method: Cut the examples and comparative examples into cylindrical specimens with a diameter of 16 mm and a height of 10 mm. According to the international standard ISO 4649-2010, use a DIN roller-type abrasion testing machine to measure the volume abrasion of the specimens. The roller diameter is 150 mm and the length is 500 mm, and it rotates clockwise at a speed of 40 r / mm. Each specimen is subjected to three parallel tests, and the average value is taken. The results are shown in Table 4.

[0072] Table 4

[0073]

[0074]

[0075] It can be found from the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 4 that the bio-based foaming material prepared by the present invention has good wear resistance.

[0076] By comparison, the volume wear of Examples 1 to 3 is less than that of Comparative Example 1, indicating that (1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde are reacted to prepare a spiropyran ultraviolet absorber, and a carbon-carbon double bond and a hydroxymethyl group are introduced onto the spiropyran ultraviolet absorber; the carbon-carbon double bond in the spiropyran ultraviolet absorber is melt grafted onto the side chain of ethylene-vinyl acetate copolymer to prepare a modified ethylene-vinyl acetate copolymer, and a hydroxymethyl group is introduced onto the side chain of the modified ethylene-vinyl acetate copolymer. The hydroxymethyl group can dehydrate with the phosphate group on phytic acid under high temperature and high pressure to form a crosslinked network, inhibit the relative slippage of molecular chains, make the finally formed cell structure stable, and at the same time improve the mechanical properties of the bio-based foaming material. The molecular chains are not easily torn by external shear forces, so the wear resistance is enhanced.

[0077] By comparison, the volume wear of Examples 1 to 3 is less than that of Comparative Example 2, indicating that pre-modified nano-silica is prepared by reacting nano-silica with 3-aminopropyltriethoxysilane, and an amino group is introduced onto the pre-modified nano-silica. 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine are polymerized and grown on the pre-modified nano-silica to prepare modified nano-silica. 1,3-diaminoguanidine hydrochloride and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine undergo thermal condensation by removing ammonia gas at high temperature, and an amino group is introduced onto the modified nano-silica. The amino group on the modified nano-silica can also dehydrate with the phosphate group on phytic acid under high temperature and high pressure to form a crosslinked network, inhibit the relative slippage of molecular chains, make the finally formed cell structure stable, and at the same time improve the mechanical properties of the bio-based foaming material. The molecular chains are not easily torn by external shear forces, so the wear resistance is enhanced; nano-silica has a high specific surface area and excellent mechanical properties, which can improve the strength and hardness of the matrix resin. Modifying the nano-silica can increase the compatibility between the nano-silica and the matrix resin, reduce the agglomeration phenomenon of the nano-silica, make the nano-silica uniformly dispersed in the matrix resin, and give full play to the reinforcing effect of the nano-silica, further improving the wear resistance of the bio-based foaming material.

[0078] By comparison, the volume wear of Examples 1 to 3 is less than that of Comparative Example 3, indicating that a bio-based foamed material is prepared by mixing and granulating modified ethylene-vinyl acetate copolymer, styrene-butadiene block copolymer, modified nano-silica, and phytic acid and performing supercritical foaming; phytic acid is an organic phosphorus compound extracted from plant seeds and contains a large number of phosphate groups. The phosphate groups in phytic acid can dehydrate with the hydroxymethyl groups on the modified ethylene-vinyl acetate copolymer and the amino groups on the modified nano-silica under high temperature and high pressure to form a cross-linked network, inhibiting the relative slippage of molecular chains, making the finally formed cell structure stable, and at the same time improving the mechanical properties of the bio-based foamed material. The molecular chains are not easily torn by external shear forces, so the wear resistance is enhanced.

[0079] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and does not limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a bio-based foaming material, characterized in that, The preparation method of the bio-based foaming material comprises the following preparation steps: (1) Mix a spiropyran ultraviolet absorber, diisopropylbenzene peroxide, and acetone evenly at a mass ratio of 1:(0.1~0.12):(3~4), stir at 10~30°C and 300~500 r / min for 3~5 min, add an ethylene-vinyl acetate copolymer that is 45~55 times the mass of the spiropyran ultraviolet absorber, continue stirring for 10~12 min, let stand for 11~13 h, place it in a plastifying instrument for melt plastification, set the plastifying temperature at 170~180°C, the screw speed at 40~50 r / min, and the plastifying time at 10~12 min, dry at 50~60°C for 3~4 h under vacuum conditions to obtain a modified ethylene-vinyl acetate copolymer; (2) React nano-silica and 3-aminopropyltriethoxysilane to obtain pre-modified nano-silica; add the pre-modified nano-silica, 1,3-diaminoguanidine hydrochloride, and 2,4-diamino-6-[3-(trifluoromethyl)phenyl]-1,3,5-triazine to a reaction kettle at a mass ratio of 1:(0.4~0.6):(0.3~0.5), stir and react at 160~180°C and 400~600 r / min for 3~4 h, cool to 70~80°C, continue stirring and reacting for 1~2 h, wash with anhydrous ethanol and deionized water 3~5 times each, and dry at 50~60°C for 7~8 h under vacuum conditions to obtain modified nano-silica; (3) By mass fraction, weigh 30~40 parts of the modified ethylene-vinyl acetate copolymer, 10~20 parts of styrene-butadiene block copolymer, 1~2 parts of modified nano-silica, and 1~1.5 parts of zinc stearate, mix them evenly, place them in a twin-screw extruder for mixing and pelletizing to obtain a mixed masterbatch; mix the mixed masterbatch, phytic acid, and di-tert-butyl peroxyisopropylbenzene at a mass ratio of 1:(0.06~0.08):(0.03~0.04), place them in a kneader, knead at 150~160°C and 300~500 r / min for 10~20 min under stirring conditions, then place them on an open mill, thin pass 6~8 times at 150~160°C, press them into a plate on a flat vulcanizer, then place them in a high-pressure foaming kettle, use nitrogen as a foaming agent for supercritical foaming, set the pressure of the high-pressure foaming kettle at 24~28 MPa, the temperature at 175~185°C, release the pressure after 1~2 h, the pressure release time is 15~25 s, and cool to room temperature to obtain the bio-based foaming material; The preparation method of the spiropyran ultraviolet absorber described in step (1) is as follows: Add (1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indol-6-yl)-methanol and 3-allylsalicylaldehyde at a molar ratio of 1:1 to methanol that is 14~16 times the mass of 3-allylsalicylaldehyde, stir and reflux at 65~75°C and 300~500 r / min for 2~3 h under a nitrogen atmosphere, and dry at 50~60°C for 7~9 h under vacuum conditions to obtain the spiropyran ultraviolet absorber.

2. The preparation method of a bio-based foaming material according to claim 1, characterized in that, The model of the ethylene-vinyl acetate copolymer described in step (1) is Y2045 18-3.

3. The preparation method of a bio-based foaming material according to claim 1, characterized in that, The preparation method of the pre-modified nano-silica described in step (2) is as follows: Mix nano-silica and absolute ethanol evenly according to a mass ratio of 1:(20~30), add a silane hydrolysis solution 8~10 times the mass of nano-silica, stir and react at 50~60°C and 300~500 r / min for 2~3 h, filter, wash with absolute ethanol 3~5 times, and dry at 70~80°C for 8~10 h under vacuum conditions to obtain the pre-modified nano-silica.

4. The preparation method of a bio-based foaming material according to claim 3, characterized in that, The preparation method of the silane hydrolysis solution is as follows: Mix 3-aminopropyltriethoxysilane and absolute ethanol evenly according to a mass ratio of 1:(40~50), adjust the pH to 4~6 with a 1 mol / L oxalic acid aqueous solution, and stir at 10~30°C and 300~500 r / min for 50~60 min to prepare the silane hydrolysis solution.

5. The preparation method of a bio-based foaming material according to claim 1, characterized in that, The model of the styrene-butadiene block copolymer described in step (3) is: HJ15A.

6. The preparation method of a bio-based foaming material according to claim 1, wherein, The process parameters of the twin-screw extruder described in step (3) are: Set the temperature of the twin-screw extruder to 170~180°C and the screw speed to 90~100 r / min.

7. The preparation method of a bio-based foaming material according to claim 1, characterized in that, The process parameters of the flat vulcanizing machine described in step (3) are: Set the temperature of the flat vulcanizing machine to 140~150°C, the pressure to 14~16 MPa, and the time to 8~10 min.

8. A bio-based foamed material prepared by the preparation method of the bio-based foamed material according to any one of claims 1~7.

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