Preparation method of simulation tree with infrared stealth camouflage characteristic

Abstract

The invention discloses a preparation method of a simulation tree with an infrared stealth camouflage characteristic, and belongs to the technical field of infrared camouflage. The preparation method is used for solving the technical problems that in the prior art, a camouflage tree for military camouflage is poor in water resistance and acid-resistant color fastness, and the infrared stealth camouflage characteristic of a simulation tree needs to be further improved, and the preparation method of the simulation tree with the infrared stealth camouflage characteristic is provided. Comprising the following steps: heating and melting infrared simulation resin imitating the color of bark, and then coating the infrared simulation resin on the outer part of a simulation tree skeleton to form a simulation coating layer with the thickness of 20-30mm on the outer part of the simulation tree skeleton. By preparing the simulation tree skeleton coated with the glass fiber and coating the simulation tree skeleton with the infrared simulation resin, the highly similar simulation tree is prepared, the water-resistant and acid-resistant color fastness of the simulation tree is improved, the moisture absorption performance of the simulation tree is also improved, the transpiration of green vegetation leaves is simulated, and the simulation tree skeleton can be used as a simulation tree. The target is fused into the natural environment, and the infrared stealth effect is improved.

Description

Technical Field

[0001] The invention relates to the technical field of infrared camouflage, and in particular to a method for preparing a simulated tree with infrared stealth camouflage characteristics. Background Art

[0002] Infrared stealth technology mainly reduces the detectability of a target by reducing or changing its infrared radiation characteristics. Specific measures include changing the infrared radiation characteristics of the target, reducing the intensity of infrared radiation, and adjusting the propagation path of infrared radiation. For example, by improving the thermal structure design, forcibly cooling the main heating components, coating the surface with infrared stealth materials, and using infrared camouflage and shielding, the infrared radiation of the target can be effectively reduced, thereby reducing the possibility of being discovered by the enemy's infrared detection system.

[0003] With the rapid development of military science and technology, modern infrared reconnaissance and aiming technology has reached an unprecedented level. Optoelectronic imaging satellites can obtain high-resolution visible light and infrared images and shoot ground targets in total darkness, which poses a serious threat to the safety of various military facilities and weapons and equipment. Therefore, the development of infrared stealth technology, especially camouflage equipment such as simulated trees with infrared stealth camouflage characteristics, has become an important direction of military scientific research in various countries.

[0004] Prior art, publication number CN103754054B discloses a simulated banyan tree and a method for making the same, which is used to solve the technical problem of poor weather resistance of existing simulated trees. Since the single branch, secondary branch, primary branch and trunk are made of injection molding mixture composed of LDPE, HDPE, EVA and compound stabilizer Ciba2020, the weather resistance of the simulated tree is improved.

[0005] However, in the field of military camouflage, artificial trees are used as an important camouflage method. Their purpose is to simulate green vegetation in the natural background, effectively eliminate the characteristic differences between military targets and the background, and integrate the targets into the natural environment. The transpiration and water absorption characteristics of existing green plants make their spectrum in the 380nm-2500nm infrared band have obvious reflection characteristics, especially the water absorption peaks near 1450nm and 1930nm are the most obvious. However, the existing artificial trees have poor hygroscopic properties. It is difficult for artificial trees to absorb moisture in the environment and it is impossible to simulate the transpiration of plants. Their performance in the infrared band is often significantly different from that of natural vegetation and is easily identified by infrared detection systems. In addition, the water and acid fastness of existing artificial trees are poor. When used for outdoor camouflage, it is difficult to maintain their color for a long time. There is an obvious color difference with the surrounding green plants. The stealth camouflage characteristics of artificial trees need to be further improved.

[0006] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing an artificial tree with infrared stealth camouflage characteristics, which is used to solve the technical problems that the camouflage trees used for military camouflage in the prior art have poor water and acid fastness, poor hygroscopicity of the artificial trees, are difficult to imitate the transpiration of plants, and have significant differences with surrounding plants in the infrared spectrum band, and the infrared stealth camouflage characteristics of the artificial trees need to be further improved.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The method for preparing a simulated tree with infrared stealth camouflage characteristics comprises the following steps:

[0010] S1, heating and melting the infrared simulation resin of the imitation bark color and coating it on the outside of the simulation tree frame to form a simulation coating layer with a thickness of 20-30 mm on the outside of the simulation tree frame;

[0011] S2, using a heated metal wire to carve bark patterns on the outside of the simulated coating to obtain a simulated tree precursor;

[0012] S3, adding infrared simulation resin with imitation leaf color into the model, raising the model temperature to 160-180°C, raising the pressure to 2-3MPa, hot pressing for 30-50s, and discharging the material to obtain simulated leaves;

[0013] S4, bonding the artificial leaves to the artificial tree precursor to obtain a crude artificial tree product;

[0014] S5, placing the crude artificial tree product in a curing room with a humidity of 70-80% and a temperature of 60-70° C. for 2-3 days to obtain an artificial tree;

[0015] The infrared simulation resin comprises 100-120 parts of composite polyolefin, 30-40 parts of polyvinyl alcohol, 20-30 parts of epoxy resin and 190-230 parts of a mixture by weight; the mixture is composed of modified wood powder, modified montmorillonite, modified nanoparticles and pigment in a species ratio of 7-8:2-3:1-2:3-4.

[0016] Furthermore, the preparation method of the simulated tree skeleton is as follows: a plurality of metal pipes are welded and fixed in the shape of a tree to obtain a rough simulated tree skeleton, and then a fiberglass fiber layer is coated on the outside of the rough simulated tree skeleton to form a skeleton similar to a leafless tree to obtain a simulated tree skeleton.

[0017] Furthermore, the fiberglass coating method is as follows: epoxy resin, glass fiber, and ABS resin are mixed in a weight ratio of 3:8:2 and heated until the system is melted to obtain a mixed glue solution, and the mixed glue solution is coated on the outside of the artificial tree skeleton rough product by a gluing process to form a glass fiber layer, which is cooled and solidified to obtain an artificial tree skeleton.

[0018] Furthermore, the processing method of the composite polyolefin is: adding hyperbranched propylene, 1,7-octadiene, allyl glycidyl ether, acryl alcohol and N,N-dimethylformamide into a reactor and stirring, raising the temperature of the reactor to 80-90° C., adding an initiator into the reactor, keeping the temperature for reaction for 6-8 hours, and post-processing to obtain the composite polyolefin;

[0019] Furthermore, the amount ratio of the hyperbranched propylene, 1,7-octadiene, allyl glycidyl ether, acryl alcohol, N,N-dimethylformamide and initiator is 6-8g:2-3g:5-6g:3-4g:40-50mL:0.5g, the initiator is azobisisobutyronitrile, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is increased to 90-100°C, and the solvent is evaporated under reduced pressure to obtain a composite polyolefin.

[0020] The synthetic reaction formula of composite polyolefin is:

[0021]

[0022] Where:

[0023] The synthetic reaction principle of composite polyolefin is:

[0024] Under the action of a free radical initiator, the olefin double bonds on hyperbranched propylene, 1,7-octadiene, allyl glycidyl ether, and allyl alcohol are broken to form free radicals, and free radical polymerization occurs to prepare an olefin copolymer with a long straight-chain structure modified with hydroxyl groups, epoxy groups, and ammonium chloride salts.

[0025] Further, the hyperbranched propylene is obtained by processing the following steps:

[0026] A1. Add 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and tetrahydrofuran into a nitrogen-protected reactor and stir. Raise the temperature of the reactor to 50-55° C., add 3-isocyanate propylene into the reactor, keep the temperature for 4-6 hours, and perform post-treatment to obtain intermediate I.

[0027] The synthetic reaction formula of intermediate I is:

[0028]

[0029] The synthetic reaction principle of intermediate I is:

[0030] During the reaction with the isocyanate group, the reactivity of the amino group is higher than that of the hydroxyl group. During the reaction, the amino group on 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol undergoes a condensation reaction with the isocyanate group on 3-isocyanatopropylene, replacing the amino group on 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol to form an olefin double bond modification, thereby preparing an intermediate I containing an olefin double bond modified triol. The mass spectrometry analysis data of the intermediate I are m / z: 288.2049 (100.0%), 289.2083 (15.1%), 290.2116 (1.1%), and the molecular weight is 288.38.

[0031] A2. Add intermediate I, trimethylammonium glycidyl chloride and tetrahydrofuran into a reactor and stir. Raise the temperature of the reactor to 50-60° C., add a catalyst into the reactor, keep the temperature for 20-22 hours, and perform post-treatment to obtain hyperbranched propylene.

[0032] The synthetic reaction formula of hyperbranched propylene is:

[0033]

[0034] The synthetic reaction principle of hyperbranched propylene is:

[0035] Under the action of the catalyst boron trifluoride etherate, the hydroxyl group of intermediate I and the epoxy group on trimethylammonium glycidyl chloride undergo ring-opening polymerization to form hyperbranched propylene modified with trimethylammonium chloride. The mass spectrometry data of hyperbranched propylene are m / z: 699.3871 (100.0%), 701.3842 (95.9%), 700.3905 (31.4%), 703.3812 (30.6%), 702.3875 (30.1%), 704.3840 (31.2%), 705.3826 (31.3%), 706.3806 (31.4%), 707.3810 (31.2%), 708.3830 (31.3%), 709.3840 (31.3%), 710.3833 (31.3%), 711.3820 (31.3%), 712.3831 (31.3%), 713.3833 (31.3%), 714.3834 (31.3%), 715.3835 (31.3%), 716.3836 (31.3%), 717.3837 (31.3%), 718.3838 (31.3%), 719.3840 (31.3%), 719.3841 (31.3%), 719.3833 (31.3%), 04.3846 (9.6%), 701.3938 (4.7%), 703.3909 (4.6%), 705.3783 (3.3%), 700.3842 (1.8%), 702.3812 (1.8%), 705.3879 (1.5%), 701.3914 (1.4%), 703.3884 (1.4%), 706.3816 (1.0%), the molecular weight of hyperbranched propylene is 701.21.

[0036] Furthermore, in step A1, the molar ratio of the 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and 3-isocyanate propylene is 1:1, the amount ratio of the 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and tetrahydrofuran is 1g:5mL, and the post-treatment comprises: after the reaction is completed, the reactor is kept at 50-55°C, and the solvent is evaporated under reduced pressure to obtain intermediate I; in step A2, the amount ratio of the intermediate I and glycidyl trimethylammonium chloride is 1mol:3mol, the amount ratio of glycidyl trimethylammonium chloride, tetrahydrofuran and catalyst is 1g:5mL:0.02g, and the catalyst is boron trifluoride etherate, and the post-treatment comprises: after the reaction is completed, the reactor is kept at 50-60°C, and the solvent is evaporated under reduced pressure to obtain hyperbranched propylene.

[0037] Furthermore, the modified wood powder is obtained by processing the following steps:

[0038] B1. Place the sawdust in a drying oven at 70-80°C, vacuum dry to constant weight, crush, and pass through a 60-mesh sieve to obtain wood powder;

[0039] B2, adding wood powder and 2-3wt% alum aqueous solution into a reactor and stirring, raising the temperature of the reactor to 60-70°C, keeping the temperature for 20-30min, and post-treating to obtain pretreated wood powder;

[0040] B3. Add the pretreated wood powder and decolorization solution into a nitrogen-protected reactor and stir. Raise the temperature of the reactor to reflux the system and stir for 40-60 minutes. Post-treat to obtain modified wood powder.

[0041] The synthetic reaction principle of modified wood powder is:

[0042] Through drying and crushing, sawdust is converted into wood powder with uniform particle size for subsequent processing. Aluminum potassium sulfate in alum is ionized in water to produce aluminum ions. These ions react with functional groups such as hydroxyl groups on the surface of wood powder to form a cross-linked or adsorbed layer, which helps the active ingredients in the decolorization solution to better contact with the surface of wood powder and improve the decolorization effect. Sodium hydroxide, sodium dithionite, anhydrous ethanol and purified water are mixed evenly in a certain proportion to obtain a decolorization solution. The sodium hydroxide in the decolorization solution plays a role in adjusting the pH value of the solution and promoting the bleaching effect of sodium dithionite; sodium dithionite, as a reducing agent, can decompose the pigment molecules in the wood powder to achieve decolorization; anhydrous ethanol may be used as a solvent to help the decolorizer better penetrate into the wood powder. Nitrogen protection prevents oxygen in the air from interfering with the reaction system, and obtains modified wood powder with lighter color and more stable properties.

[0043] Furthermore, in step B1, the sawdust is camphor, pine, poplar or fir sawdust; in step B2, the ratio of the wood powder to the 2-3wt% alum aqueous solution is 3g:10mL, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, suction filtration is performed, the filter cake is washed twice with purified water and then dried, the filter cake is transferred to a drying oven at a temperature of 70-80°C, and dried to constant weight to obtain pretreated wood powder; in step B3, the ratio of the pretreated wood powder to the decolorization solution is 1g:4mL, and the decolorization solution is composed of sodium hydroxide, sodium dithionite, anhydrous ethanol and purified water in a ratio of 4g:3g:6mL:15mL, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, suction filtration is performed, the filter cake is washed with purified water until neutral and then dried, and the filter cake is transferred to a drying oven at a temperature of 70-80°C, and dried to constant weight to obtain modified wood powder.

[0044] Furthermore, the preparation method of the modified montmorillonite is: adding tetrakis(2-hydroxyethyl)ammonium bromide and purified water into a reactor and stirring to dissolve, adding montmorillonite into the reactor, raising the temperature of the reactor to 70-80°C, keeping the temperature and stirring for 6-8h, and post-treating to obtain the modified montmorillonite.

[0045] The synthetic reaction principle of modified montmorillonite is:

[0046] Montmorillonite is a layered silicate mineral with exchangeable cations such as sodium ions and calcium ions between its layers. Tetrakis(2-hydroxyethyl)ammonium bromide is a quaternary ammonium salt with a long-chain alkyl group and a quaternary ammonium cation. When the tetrakis(2-hydroxyethyl)ammonium bromide solution is mixed with montmorillonite, the quaternary ammonium cations in the tetrakis(2-hydroxyethyl)ammonium bromide molecules begin to undergo an ion exchange reaction with the sodium ions between the montmorillonite layers. The tetrakis(2-hydroxyethyl)ammonium bromide quaternary ammonium cations gradually occupy the positions between the montmorillonite layers, displacing the original cations to form an intercalation modification, thereby preparing a modified montmorillonite.

[0047] Furthermore, the dosage ratio of tetrakis(2-hydroxyethyl)ammonium bromide, purified water and montmorillonite is 3g:30mL:7g, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, the filter cake is washed twice with purified water and then dried, and the filter cake is transferred to a drying oven at a temperature of 70-80°C and dried to constant weight to obtain modified montmorillonite.

[0048] Furthermore, the infrared simulation resin is obtained by processing the following steps:

[0049] C1. Evenly mixing the modified wood powder, the modified montmorillonite, the modified nanoparticles and the pigment to obtain mixed particles;

[0050] C2. Add the composite polyolefin, polyvinyl alcohol and epoxy resin into a torque rheometer protected by nitrogen, increase the temperature of the torque rheometer to 160-180°C, rotate at 50-60r / min, and stir for 20-30min. Add the mixed particles into the torque rheometer in batches, stir for 40-50min, cool and discharge, seal and maintain, and obtain infrared simulation resin.

[0051] Furthermore, in step C1, the usage ratio of the modified wood powder, modified montmorillonite, modified nanoparticles and pigment is 7-8g:2-3g:1-2g:1-1.5g; in step C2, the weight ratio of the composite polyolefin, polyvinyl alcohol, epoxy resin and mixed material is 10-12:3-4:2-3:19-23.

[0052] Furthermore, the preparation method of the modified nanoparticles is as follows: adding the nanoparticles and ethanol aqueous solution into a reactor and stirring, raising the temperature of the reactor to 50-60° C., adding KH-550 into the reactor, keeping the temperature for reaction for 3-5 hours, and post-treating to obtain the modified nanoparticles.

[0053] The synthetic reaction formula of modified nanoparticles is:

[0054]

[0055] Where: For nanoparticles.

[0056] The synthetic reaction principle of modified nanoparticles is:

[0057] The silyl group in the KH-550 molecule undergoes a hydrolysis reaction in an ethanol aqueous solution to generate silanol, which can further undergo a condensation reaction with the hydroxyl group on the surface of the nanoparticles to form a more stable silicon-oxygen bond connection, thereby strengthening the bond between the nanoparticles and KH-550 and possibly forming a new surface modification layer to prepare modified nanoparticles.

[0058] Furthermore, the dosage ratio of the nanoparticles, the ethanol aqueous solution and KH-550 is 7g:30mL:3g, the nanoparticles are composed of nano-calcium carbonate and nano-barium sulfate in a weight ratio of 3:1, the ethanol aqueous solution is composed of anhydrous ethanol, purified water, sodium dodecyl sulfate and sodium hydroxide in a dosage ratio of 70mL:40mL:2g:5g, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, suction filtration, the filter cake is washed with purified water until it is neutral and then dried, the filter cake is transferred to a drying oven with a temperature of 70-80°C, and vacuum dried to constant weight to obtain modified nanoparticles.

[0059] The present invention has the following beneficial effects:

[0060] 1. The artificial tree with infrared stealth camouflage characteristics of the present invention is prepared by coating a glass fiber layer on the outside of a metal pipe to obtain an artificial tree frame, and coating the artificial tree frame with a coating composed of an infrared simulation resin and camouflage leaves to obtain an artificial tree; by coating the artificial tree frame with a glass fiber layer, the artificial tree can resist the erosion of substances such as moisture, acid and alkali, prolong the service life of the artificial tree, and improve the overall structural strength of the artificial tree; when preparing the infrared simulation resin, the hyperbranched propylene modified with trimethylammonium chloride is condensed with the olefin material to prepare a composite polyolefin, and the modified nanoparticles are used to enhance the pigment so that the pigment can It can be evenly dispersed and remain stable in the composite polyolefin, and is reinforced with modified wood powder and modified montmorillonite as fillers to improve the hygroscopicity of the infrared simulation resin, so that the infrared simulation resin layer on the simulated tree has good water absorption performance, so as to simulate the plants under the conditions of ambient temperature, humidity and solar radiation, and independently realize the adsorption / desorption of water vapor molecules through the infrared simulation resin, simulate the transpiration of green vegetation leaves, so that the spectral reflectance characteristics of the simulated plants are similar to those of green plants, and the simulated trees are integrated with the surrounding green plants, effectively eliminating the characteristic differences between military targets and the background, so that the targets are integrated into the natural environment and achieve infrared stealth effect.

[0061] 2. The artificial tree with infrared stealth camouflage characteristics of the present invention is prepared by free radical reaction of hyperbranched propylene modified with poly(trimethylammonium chloride) with 1,7-octadiene, allyl glycidyl ether, and acryl alcohol under the action of an initiator to obtain a composite polyolefin having trimethylammonium chloride, epoxy and hydroxyl modified polyolefin segments. Trimethylammonium chloride is used as a cationic surfactant. The trimethylammonium chloride group carries a positive charge and can undergo ion exchange with negatively charged azo pigment molecules. Moreover, its modification on the polyolefin segment can reduce the surface tension of the polyolefin, making the pigment particles easier to be wetted and dispersed, reducing the agglomeration phenomenon between the pigment particles, and increasing the dispersion of the azo pigment in the composite polyolefin. The modified epoxy and hydroxyl groups in the composite polyolefin can interact with the functional groups on the surface of the azo pigment. , enhance the binding force between the pigment and the polyolefin chain segment, and improve the water resistance of the pigment in the composite polyolefin; nano calcium carbonate and barium sulfate, as dispersants or carriers, can adsorb and fix azo pigment particles to prevent them from agglomerating and settling in polyolefins. The nanoparticles are modified by KH-550 to improve the dispersibility of nano calcium carbonate and nano barium sulfate in composite polyolefins and improve their chemical stability, so that the azo pigment is evenly distributed and stably exists in the composite material. In addition, the nanoparticles and the polyolefin matrix undergo ring-opening condensation through epoxy groups and amino groups to improve the interfacial binding force between molecules, thereby firmly fixing the azo pigment in the composite polyolefin, reducing its shedding and fading in external media, and significantly enhancing the water and acid resistance of the azo pigment in the composite polyolefin.

[0062] 3. The artificial tree with infrared stealth camouflage characteristics of the present invention is prepared by modifying wood powder and montmorillonite. The wood powder itself contains more hydrophilic groups and pore structures, and is easy to absorb and retain moisture. By decolorizing and modifying it, its own color is reduced, and the infrared simulation resin is easier to be dyed evenly. Montmorillonite itself has good hygroscopic properties. The montmorillonite is modified by tetrakis(2-hydroxyethyl)ammonium bromide to increase the number of its hydrophilic groups, thereby improving its hygroscopicity, so that when the modified montmorillonite is added to the composite polyolefin as a filler, it can increase The moisture absorption channel in the composite material is strengthened, and the moisture absorption performance of the infrared simulation resin is improved. The uniform dispersion of modified wood powder and modified montmorillonite in the composite polyolefin can reduce the occurrence of interface reflection and scattering, thereby reducing light scattering and color changes caused by interface unevenness, improving the color uniformity and stability of the material, and improving the simulation effect of the simulated tree. Moreover, when modified montmorillonite and modified wood powder are used as fillers together, they can further reduce the direct irradiation of ultraviolet light to the composite polyolefin matrix, reduce the occurrence rate of photodegradation reaction, and thus improve the color stability of the simulated tree material. DETAILED DESCRIPTION

[0063] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] The epoxy resin in the present application is bisphenol A epoxy resin, model E-44, and epoxy value is 0.41-0.47eq / 100g; the molecular weight of polyvinyl alcohol is 25,000-35,000; the product model of ABS resin is MG37EP, the melt flow rate is 4.4g / 10min, and the Vicat softening point is 101°C.

[0065] Example 1

[0066] This embodiment provides a method for preparing an infrared simulation resin for a simulated tree having infrared stealth camouflage characteristics, comprising the following steps:

[0067] Preparation of composite polyolefins

[0068] Weigh: 205.4 g of 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and 1027 mL of tetrahydrofuran are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to 50° C., 83.1 g of 3-isocyanate propylene is added to the reactor, and the reaction is kept warm for 4 hours. After the reaction is completed, the reactor is kept warm at 50° C., and the solvent is evaporated under reduced pressure to obtain intermediate I;

[0069] Weigh: 288.4 g of intermediate I, 454.9 g of trimethylammonium glycidyl chloride and 1442 mL of tetrahydrofuran, add them into a reactor and stir, raise the temperature of the reactor to 50° C., add 9.1 g of boron trifluoride etherate into the reactor, and keep the temperature for 20 hours. After the reaction is completed, keep the reactor at 50° C., and evaporate the solvent under reduced pressure to obtain hyperbranched propylene;

[0070] Weigh: 180 g of hyperbranched propylene, 60 g of 1,7-octadiene, 150 g of allyl glycidyl ether, 90 g of acryl alcohol and 1200 mL of N,N-dimethylformamide, add into a reactor and stir, raise the temperature of the reactor to 80°C, add 1.5 g of azobisisobutyronitrile into the reactor, keep warm and react for 6 hours, after the reaction is completed, raise the temperature of the reactor to 90°C, evaporate the solvent under reduced pressure to obtain a composite polyolefin.

[0071] Preparation of modified wood flour

[0072] Place camphor wood sawdust and pine wood sawdust in a drying oven at 70°C, vacuum dry to constant weight, crush, and pass through a 60-mesh sieve to obtain wood powder;

[0073] Weigh: 90 g of wood powder and 300 mL of 2 wt% alum aqueous solution are added to a reactor and stirred, the temperature of the reactor is raised to 60° C., and the reactor is kept warm for 20 minutes. After the reaction is completed, the temperature of the reactor is lowered to room temperature, and the filter cake is filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 70° C. and dried to constant weight to obtain pretreated wood powder;

[0074] Mix sodium hydroxide, sodium dithionite, anhydrous ethanol and purified water in a ratio of 4g:3g:6mL:15mL to obtain a decolorizing solution for later use;

[0075] Weigh: 80 g of pretreated wood powder and 320 mL of decolorization solution are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to reflux and stirred for 40 minutes. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 70°C and dried to constant weight to obtain modified wood powder.

[0076] Preparation of modified montmorillonite

[0077] Weigh: 30 g of tetrakis (2-hydroxyethyl) ammonium bromide and 300 mL of purified water are added to a reactor and stirred to dissolve, 70 g of montmorillonite is added to the reactor, the temperature of the reactor is raised to 70°C, and the mixture is kept warm and stirred for 6 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 70°C and dried to constant weight to obtain modified montmorillonite.

[0078] Preparation of modified nanoparticles

[0079] The nano-calcium carbonate and the nano-barium sulfate are mixed uniformly in a weight ratio of 3:1 to obtain nano-particles;

[0080] Anhydrous ethanol, purified water, sodium dodecyl sulfate and sodium hydroxide were uniformly mixed in a dosage ratio of 70 mL:40 mL:2 g:5 g to obtain an ethanol aqueous solution;

[0081] Weigh: 70 g of nanoparticles and 300 mL of ethanol aqueous solution are added to the reactor and stirred. The temperature of the reactor is raised to 50°C, 30 g of KH-550 is added to the reactor, and the reaction is kept warm for 3 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 70°C and vacuum dried to constant weight to obtain modified nanoparticles.

[0082] Preparation of infrared simulation resin

[0083] Select red, green and blue azo pigments as base pigments, and blend the three primary colors according to the required colors to obtain pigments;

[0084] Weigh: 140 g of modified wood powder, 40 g of modified montmorillonite, 20 g of modified nanoparticles and 20 g of pigment, mix them evenly to obtain mixed particles;

[0085] Weigh: 1.0 kg of composite polyolefin, 300 g of polyvinyl alcohol, and 200 g of epoxy resin and add them into a torque rheometer protected by nitrogen. The temperature of the torque rheometer is raised to 160°C, the speed is 50 r / min, and the mixture is stirred for 20 minutes. 1.9 kg of mixed particles are added to the torque rheometer in batches, and the mixture is stirred for 40 minutes. The temperature is lowered and the material is discharged. The material is sealed and maintained to obtain an infrared simulation resin.

[0086] Example 2

[0087] This embodiment provides a method for preparing an infrared simulation resin for a simulated tree having infrared stealth camouflage characteristics, comprising the following steps:

[0088] Preparation of composite polyolefins

[0089] Weigh: 205.4 g of 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and 1027 mL of tetrahydrofuran are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to 53° C., 83.1 g of 3-isocyanate propylene is added to the reactor, and the reaction is kept warm for 5 hours. After the reaction is completed, the reactor is kept warm at 53° C., and the solvent is evaporated under reduced pressure to obtain intermediate I;

[0090] Weigh: 288.4 g of intermediate I, 454.9 g of trimethylammonium glycidyl chloride and 1442 mL of tetrahydrofuran, add them into a reactor and stir, raise the temperature of the reactor to 55° C., add 9.1 g of boron trifluoride etherate into the reactor, and keep the temperature for 21 hours. After the reaction is completed, keep the reactor at 55° C., and evaporate the solvent under reduced pressure to obtain hyperbranched propylene;

[0091] Weigh: 210 g of hyperbranched propylene, 75 g of 1,7-octadiene, 165 g of allyl glycidyl ether, 105 g of acryl alcohol and 1350 mL of N,N-dimethylformamide, add into a reactor and stir, raise the temperature of the reactor to 85°C, add 1.5 g of azobisisobutyronitrile into the reactor, keep warm and react for 7 hours, after the reaction is completed, raise the temperature of the reactor to 95°C, evaporate the solvent under reduced pressure to obtain a composite polyolefin.

[0092] Preparation of modified wood flour

[0093] Place pine wood chips and poplar wood chips in a drying oven at 75°C, vacuum dry to constant weight, crush, and pass through a 60-mesh sieve to obtain wood powder;

[0094] Weigh: 90 g of wood powder and 300 mL of 2.5 wt% alum aqueous solution are added to a reactor and stirred. The temperature of the reactor is raised to 65° C. and kept warm for 25 minutes. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 75° C. and dried to constant weight to obtain pretreated wood powder;

[0095] Mix sodium hydroxide, sodium dithionite, anhydrous ethanol and purified water in a ratio of 4g:3g:6mL:15mL to obtain a decolorizing solution for later use;

[0096] Weigh: 80 g of pretreated wood powder and 320 mL of decolorization solution are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to reflux and stirred for 50 minutes. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 75°C and dried to constant weight to obtain modified wood powder.

[0097] Preparation of modified montmorillonite

[0098] Weigh: 30 g of tetrakis (2-hydroxyethyl) ammonium bromide and 300 mL of purified water are added to a reactor and stirred to dissolve, 70 g of montmorillonite is added to the reactor, the temperature of the reactor is raised to 75°C, and the mixture is kept warm and stirred for 7 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 75°C and dried to constant weight to obtain modified montmorillonite.

[0099] Preparation of modified nanoparticles

[0100] The nano-calcium carbonate and the nano-barium sulfate are mixed uniformly in a weight ratio of 3:1 to obtain nano-particles;

[0101] Anhydrous ethanol, purified water, sodium dodecyl sulfate and sodium hydroxide were uniformly mixed in a dosage ratio of 70 mL:40 mL:2 g:5 g to obtain an ethanol aqueous solution;

[0102] Weigh: 70 g of nanoparticles and 300 mL of ethanol aqueous solution are added to the reactor and stirred. The temperature of the reactor is raised to 55°C, 30 g of KH-550 is added to the reactor, and the reaction is kept warm for 4 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 75°C and vacuum dried to constant weight to obtain modified nanoparticles.

[0103] Preparation of infrared simulation resin

[0104] Select red, green and blue azo pigments as base pigments, and blend the three primary colors according to the required colors to obtain pigments;

[0105] Weigh: 150 g of modified wood powder, 50 g of modified montmorillonite, 30 g of modified nanoparticles and 25 g of pigment, mix them evenly to obtain mixed particles;

[0106] Weigh: 1.1 kg of composite polyolefin, 350 g of polyvinyl alcohol, and 250 g of epoxy resin and add them into a torque rheometer protected by nitrogen. The temperature of the torque rheometer is raised to 170°C, the speed is 55 r / min, and the mixture is stirred for 25 minutes. 2.1 kg of mixed particles are added to the torque rheometer in batches, and the mixture is stirred for 45 minutes. The temperature is reduced and the material is discharged and sealed to obtain an infrared simulation resin.

[0107] Example 3

[0108] This embodiment provides a method for preparing an infrared simulation resin for a simulated tree having infrared stealth camouflage characteristics, comprising the following steps:

[0109] Preparation of composite polyolefins

[0110] Weigh: 205.4 g of 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and 1027 mL of tetrahydrofuran are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to 55° C., 83.1 g of 3-isocyanate propylene is added to the reactor, and the reaction is kept warm for 6 hours. After the reaction is completed, the reactor is kept warm at 55° C., and the solvent is evaporated under reduced pressure to obtain intermediate I;

[0111] Weigh: 288.4 g of intermediate I, 454.9 g of trimethylammonium glycidyl chloride and 1442 mL of tetrahydrofuran, add them into a reactor and stir, raise the temperature of the reactor to 60° C., add 9.1 g of boron trifluoride etherate into the reactor, and keep the temperature for 22 hours. After the reaction is completed, keep the reactor at 60° C., and evaporate the solvent under reduced pressure to obtain hyperbranched propylene;

[0112] Weigh: 240 g of hyperbranched propylene, 90 g of 1,7-octadiene, 180 g of allyl glycidyl ether, 120 g of acryl alcohol and 1500 mL of N,N-dimethylformamide, add into a reactor and stir, raise the temperature of the reactor to 90°C, add 1.5 g of azobisisobutyronitrile into the reactor, keep warm and react for 8 hours, after the reaction is completed, raise the temperature of the reactor to 100°C, evaporate the solvent under reduced pressure to obtain a composite polyolefin.

[0113] Preparation of modified wood flour

[0114] Place poplar wood chips and fir wood chips in a drying oven at 80°C, vacuum dry to constant weight, crush, and pass through a 60-mesh sieve to obtain wood powder;

[0115] Weigh: 90 g of wood powder and 300 mL of 3 wt% alum aqueous solution are added to a reactor and stirred. The temperature of the reactor is raised to 70° C. and the reactor is kept warm for 30 minutes. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a drying oven at a temperature of 80° C. and dried to constant weight to obtain pretreated wood powder;

[0116] Mix sodium hydroxide, sodium dithionite, anhydrous ethanol and purified water in a ratio of 4g:3g:6mL:15mL to obtain a decolorizing solution for later use;

[0117] Weigh: 80 g of pretreated wood powder and 320 mL of decolorization solution are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to reflux and stirred for 60 minutes. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 80°C and dried to constant weight to obtain modified wood powder.

[0118] Preparation of modified montmorillonite

[0119] Weigh: 30 g of tetrakis(2-hydroxyethyl)ammonium bromide and 300 mL of purified water are added to a reactor and stirred to dissolve, 70 g of montmorillonite is added to the reactor, the temperature of the reactor is raised to 80°C, and the mixture is kept warm and stirred for 8 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed twice with purified water and then dried. The filter cake is transferred to a drying oven at 80°C and dried to constant weight to obtain modified montmorillonite.

[0120] Preparation of modified nanoparticles

[0121] The nano-calcium carbonate and the nano-barium sulfate are mixed uniformly in a weight ratio of 3:1 to obtain nano-particles;

[0122] Anhydrous ethanol, purified water, sodium dodecyl sulfate and sodium hydroxide were uniformly mixed in a dosage ratio of 70 mL:40 mL:2 g:5 g to obtain an ethanol aqueous solution;

[0123] Weigh: 70 g of nanoparticles and 300 mL of ethanol aqueous solution are added to the reactor and stirred. The temperature of the reactor is raised to 60°C, 30 g of KH-550 is added to the reactor, and the reaction is kept warm for 5 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, filtered, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain modified nanoparticles.

[0124] Preparation of infrared simulation resin

[0125] Select red, green and blue azo pigments as base pigments, and blend the three primary colors according to the required colors to obtain pigments;

[0126] Weigh: 160 g of modified wood powder, 60 g of modified montmorillonite, 40 g of modified nanoparticles and 30 g of pigment, mix them evenly to obtain mixed particles;

[0127] Weigh: 1.2 kg of composite polyolefin, 400 g of polyvinyl alcohol, and 300 g of epoxy resin and add them into a torque rheometer protected by nitrogen. The temperature of the torque rheometer is raised to 180°C, the speed is 60 r / min, and the mixture is stirred for 30 minutes. 2.3 kg of mixed particles are added to the torque rheometer in batches, and the mixture is stirred for 50 minutes. The temperature is lowered and the material is discharged. The material is sealed and maintained to obtain an infrared simulation resin.

[0128] Example 4

[0129] This embodiment provides a method for preparing a simulated tree with infrared stealth camouflage characteristics, comprising the following steps:

[0130] Step 1: Weld and fix several metal pipes in the shape of a tree to obtain a rough product of a simulated tree skeleton. Mix epoxy resin, glass fiber, and ABS resin in a weight ratio of 3:8:2 and heat until the system is melted to obtain a mixed glue solution. Use a gluing process to coat the mixed glue solution on the outside of the rough product of the simulated tree skeleton to form a glass fiber layer. Cool and solidify to form a skeleton similar to a leafless tree to obtain a simulated tree skeleton.

[0131] Cement concrete is poured into the model, cured and solidified, and a simulated tree skeleton with branches is prepared.

[0132] Step 2: Heat and melt the infrared simulation resin with the imitation bark color prepared in Example 1 and then coat it on the outside of the simulated tree skeleton to form a simulation coating layer with a thickness of 20 mm on the outside of the simulated tree skeleton.

[0133] Step 3: Use a heated metal wire to carve bark patterns on the outside of the simulated coating to obtain a simulated tree precursor.

[0134] Step 4: Add the infrared simulation resin with the leaf-like color prepared in Example 1 into the model, increase the model temperature to 160° C., increase the pressure to 2 MPa, and hot-press for 30 seconds to obtain simulated leaves.

[0135] Step 5: Bond the simulated leaves to the simulated tree precursor to obtain a simulated tree crude product.

[0136] Step 6: Place the crude artificial tree in a curing room with a humidity of 70% and a temperature of 60° C. for 2 days to obtain an artificial tree.

[0137] Example 5

[0138] This embodiment provides a method for preparing a simulated tree with infrared stealth camouflage characteristics, comprising the following steps:

[0139] Step 1: Weld and fix several metal pipes in the shape of a tree to obtain a rough product of a simulated tree skeleton. Mix epoxy resin, glass fiber, and ABS resin in a weight ratio of 3:8:2 and heat until the system is melted to obtain a mixed glue solution. Use a gluing process to coat the mixed glue solution on the outside of the rough product of the simulated tree skeleton to form a glass fiber layer. Cool and solidify to form a skeleton similar to a leafless tree to obtain a simulated tree skeleton.

[0140] Step 2: Heat and melt the infrared simulation resin with the imitation bark color prepared in Example 2 and then coat it on the outside of the simulated tree skeleton to form a simulation coating layer with a thickness of 25 mm on the outside of the simulated tree skeleton.

[0141] Step 3: Use a heated metal wire to carve bark patterns on the outside of the simulated coating to obtain a simulated tree precursor.

[0142] Step 4: Add the infrared simulation resin with the leaf-like color prepared in Example 2 into the model, increase the model temperature to 170° C., increase the pressure to 2.5 MPa, and hot press for 40 seconds to obtain simulated leaves.

[0143] Step 5: Bond the simulated leaves to the simulated tree precursor to obtain a simulated tree crude product.

[0144] Step 6: Place the crude artificial tree in a curing room with a humidity of 75% and a temperature of 65° C. for 2.5 days to obtain the artificial tree.

[0145] Example 6

[0146] This embodiment provides a method for preparing a simulated tree with infrared stealth camouflage characteristics, comprising the following steps:

[0147] Step 1: Weld and fix several metal pipes in the shape of a tree to obtain a rough product of a simulated tree skeleton. Mix epoxy resin, glass fiber, and ABS resin in a weight ratio of 3:8:2 and heat until the system is melted to obtain a mixed glue solution. Use a gluing process to coat the mixed glue solution on the outside of the rough product of the simulated tree skeleton to form a glass fiber layer. Cool and solidify to form a skeleton similar to a leafless tree to obtain a simulated tree skeleton.

[0148] Step 2: Heat and melt the infrared simulation resin with the imitation bark color prepared in Example 3 and then coat it on the outside of the simulated tree skeleton to form a simulation coating layer with a thickness of 30 mm on the outside of the simulated tree skeleton.

[0149] Step 3: Use a heated metal wire to carve bark patterns on the outside of the simulated coating to obtain a simulated tree precursor.

[0150] Step 4: Add the infrared simulation resin with the leaf-like color prepared in Example 3 into the model, increase the model temperature to 180° C., increase the pressure to 3 MPa, and hot-press for 50 seconds to obtain simulated leaves.

[0151] Step 5: Bond the simulated leaves to the simulated tree precursor to obtain a simulated tree crude product.

[0152] Step 6: Place the crude artificial tree product in a curing room with a humidity of 80% and a temperature of 70° C. for 3 days to obtain the artificial tree.

[0153] Comparative Example 1

[0154] The difference between this comparative example and Example 6 is that, during the preparation of the infrared simulation resin used, the intermediate I in step S1 is used to replace the hyperbranched propylene to prepare the composite polyolefin.

[0155] Comparative Example 2

[0156] The difference between this comparative example and Example 6 is that, when preparing the infrared simulation resin used, step S3 is omitted, and modified montmorillonite is not added in step S5.

[0157] Comparative Example 3

[0158] The difference between this comparative example and Example 6 is that, when preparing the infrared simulation resin used, step S4 is omitted, and no modified nanoparticles are added in step S5.

[0159] Comparative Example 4

[0160] The difference between this comparative example and Example 6 is that, when preparing the infrared simulation resin used, step S4 is omitted, and the modified particles in step S5 are replaced by the nanoparticles in step S4.

[0161] Performance Test:

[0162] The color stability, hygroscopicity and infrared stealth performance of the simulated trees prepared in Examples 4-6 and Comparative Examples 1-4 were tested, wherein the color stability was determined according to the standard JC / T 2427-2017 "Test method for color fastness of wood-plastic composite materials to chlorine water" to determine the water resistance and chlorine water color fastness grades of the simulated trees, and the hygroscopic and moisturizing performance was determined according to the standard GB / T 41767-2022 "Test method for hygroscopicity and equilibrium state adjustment of polymer-based composite materials" to determine the moisture diffusion coefficient of the simulated tree along the thickness direction, and the infrared stealth performance was determined according to the standard HB20540-2018 "Test method for infrared emissivity of stealth materials" to determine the infrared emissivity of the simulated tree at 1450nm and 1930nm in an environment with a humidity of 70-80%. The specific test results are shown in Table 1.

[0163] Table 1. Performance test data of samples

[0164]

[0165]

[0166] Data Analysis:

[0167] Comparing and analyzing the data in Table 1 above, the wet diffusion coefficient of the artificial tree prepared by the present invention reaches 2.71×10 -4 mm 2 / s, the color fastness to water and chlorine water both reach level 5, the infrared emissivity at 1450nm reaches 0.82, and the infrared emissivity at 1930nm reaches 0.86. The performance test data are all better than the comparative example, indicating that the present invention uses trimethylammonium chloride to modify the hyperbranched propylene of olefin and olefin basic raw materials for condensation to prepare composite polyolefin, and then the nanoparticles are modified and enhanced so that the azo pigment can be uniformly dispersed and stable in the composite polyolefin, and then the modified wood powder and modified montmorillonite are used as fillers to prepare infrared simulation resin, which is coated on the simulated tree skeleton to prepare the simulated tree, which not only effectively improves the dispersion uniformity of the pigment, prepares a highly similar simulated tree, improves the water and acid color fastness of the simulated tree, but also improves the hygroscopicity of the simulated tree, simulates the transpiration of green vegetation leaves, integrates the simulated tree with the surrounding green plants, effectively eliminates the characteristic differences between the military target and the background, integrates the target into the natural environment, and improves the infrared stealth effect.

[0168] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0169] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0170] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a simulated tree with infrared stealth camouflage characteristics, characterized in that: The following steps are involved: S1, heating and melting the infrared simulation resin of the imitation bark color and coating it on the outside of the simulation tree frame to form a simulation coating layer with a thickness of 20-30 mm on the outside of the simulation tree frame; S2, using a heated metal wire to carve bark patterns on the outside of the simulated coating to obtain a simulated tree precursor; S3, adding infrared simulation resin with imitation leaf color into the model, raising the model temperature to 160-180°C, raising the pressure to 2-3MPa, hot pressing for 30-50s, and discharging the material to obtain simulated leaves; S4, bonding the artificial leaves to the artificial tree precursor to obtain a crude artificial tree product; S5, placing the crude artificial tree product in a curing room with a humidity of 70-80% and a temperature of 60-70°C for 2-3 days to obtain an artificial tree; The infrared simulation resin comprises 100-120 parts of composite polyolefin, 30-40 parts of polyvinyl alcohol, 20-30 parts of epoxy resin and 190-230 parts of a mixture by weight; the mixture is composed of modified wood powder, modified montmorillonite, modified nanoparticles and pigment in a species ratio of 7-8:2-3:1-2:3-4.

2. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 1, characterized in that: The processing method of the composite polyolefin is as follows: hyperbranched propylene, 1,7-octadiene, allyl glycidyl ether, acryl alcohol and N,N-dimethylformamide are added into a reaction kettle and stirred, the temperature of the reaction kettle is increased to 80-90° C., an initiator is added into the reaction kettle, the reaction is carried out by heat preservation for 6-8 hours, and the composite polyolefin is obtained by post-processing.

3. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 2, characterized in that: The usage ratio of the hyperbranched propylene, 1,7-octadiene, allyl glycidyl ether, acryl alcohol, N,N-dimethylformamide and initiator is 6-8g:2-3g:5-6g:3-4g:40-50mL:0.5g, and the initiator is azobisisobutyronitrile.

4. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 2, characterized in that: The hyperbranched propylene is obtained by processing the following steps: A1. Add 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and tetrahydrofuran into a nitrogen-protected reactor and stir. Raise the temperature of the reactor to 50-55° C., add 3-isocyanate propylene into the reactor, keep the temperature for 4-6 hours, and perform post-treatment to obtain intermediate I. A2. Add intermediate I, trimethylammonium glycidyl chloride and tetrahydrofuran into a reactor and stir. Raise the temperature of the reactor to 50-60° C., add a catalyst into the reactor, keep the temperature for 20-22 hours, and perform post-treatment to obtain hyperbranched propylene.

5. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 4, characterized in that: In step A1, the molar ratio of 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and 3-isocyanate propylene is 1:1, and the amount ratio of 4-amino-4-(3-hydroxypropyl)-1,7-heptanediol and tetrahydrofuran is 1g:5mL; in step A2, the amount ratio of intermediate I and glycidyl trimethylammonium chloride is 1mol:3mol, and the amount ratio of glycidyl trimethylammonium chloride, tetrahydrofuran and catalyst is 1g:5mL: 0.02g, the catalyst is boron trifluoride etherate.

6. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 1, characterized in that: The modified wood powder is obtained by processing the following steps: B1. Place the sawdust in a drying oven at 70-80°C, vacuum dry to constant weight, crush, and pass through a 60-mesh sieve to obtain wood powder; B2, adding wood powder and 2-3wt% alum aqueous solution into a reactor and stirring, raising the temperature of the reactor to 60-70°C, keeping the temperature for 20-30min, and post-treating to obtain pretreated wood powder; B3. Add the pretreated wood powder and decolorization solution into a nitrogen-protected reactor and stir. Raise the temperature of the reactor to reflux the system and stir for 40-60 minutes. Post-treat to obtain modified wood powder.

7. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 6, characterized in that: In step B1, the sawdust is camphor, pine, poplar or fir sawdust; in step B2, the ratio of the wood powder to the 2-3wt% alum aqueous solution is 3g:10mL; in step B3, the ratio of the pretreated wood powder to the decolorization solution is 1g:4mL, and the decolorization solution is composed of sodium hydroxide, sodium dithionite, anhydrous ethanol and purified water in a ratio of 4g:3g:6mL:15mL.

8. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 1, characterized in that: The preparation method of the modified montmorillonite comprises: adding tetrakis(2-hydroxyethyl)ammonium bromide and purified water into a reaction kettle, stirring and dissolving, adding montmorillonite into the reaction kettle, raising the temperature of the reaction kettle to 70-80° C., keeping the temperature and stirring for 6-8 hours, and post-treating to obtain the modified montmorillonite, wherein the usage ratio of the tetrakis(2-hydroxyethyl)ammonium bromide, purified water and montmorillonite is 3g:30mL:7g.

9. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 1, characterized in that: The infrared simulation resin is obtained by processing the following steps: C1. Evenly mixing the modified wood powder, the modified montmorillonite, the modified nanoparticles and the pigment to obtain mixed particles; C2. Add the composite polyolefin, polyvinyl alcohol and epoxy resin into a torque rheometer protected by nitrogen, increase the temperature of the torque rheometer to 160-180°C, rotate at 50-60r / min, and stir for 20-30min. Add the mixed particles into the torque rheometer in batches, stir for 40-50min, cool and discharge, seal and maintain, and obtain infrared simulation resin.

10. The method for preparing a simulated tree with infrared stealth camouflage characteristics according to claim 1, characterized in that: The preparation method of the modified nanoparticles is as follows: adding nanoparticles and ethanol aqueous solution into a reactor and stirring, raising the temperature of the reactor to 50-60° C., adding KH-550 into the reactor, keeping the temperature for reaction for 3-5 hours, and post-treating to obtain the modified nanoparticles.

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