Method for preparing infrared stealth leather based on phase change microcapsules

Abstract

The application discloses a preparation method of infrared stealth leather based on phase change microcapsules, and specifically comprises the following steps: step 1, preparing phase change microcapsules of SiO2 coated phase change materials; step 2, preparing phase change microcapsules of phase change material@SiO2 / ZnO; step 3, preparing phase change microcapsule-polyurethane composite coating emulsion of phase change material@SiO2 / ZnO; and step 4, coating the phase change microcapsule-polyurethane composite coating emulsion of phase change material@SiO2 / ZnO obtained in step 3 on the surface of leather in batches to obtain infrared stealth leather. The phase change microcapsules with temperature control and low infrared emission are used, the synergistic effect of the phase change heat regulation capacity of the core phase change material of the microcapsules and the low infrared emissivity of the shell is achieved, high-efficiency infrared stealth is realized, the phase change microcapsules are combined with polyurethane, and the coating is coated on the surface of the leather in the form of brushing to construct the infrared stealth leather.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional materials, and relates to a preparation method of infrared stealth leather based on phase change microcapsules. BACKGROUND

[0002] Leather is a kind of porous network flexible substrate woven by natural fibers, has outstanding physical and mechanical strength and certain heat insulation, and its heat insulation effect cannot reach the infrared stealth effect, therefore, processing the leather with infrared stealth materials to enhance the temperature control and reduce the infrared emissivity is an effective means to obtain ideal wearable leather-based infrared stealth materials. However, the reported infrared stealth leather at present introduces a single low infrared radiation nanomaterial in the leather processing process, cannot control the temperature of the stealth target, and makes the infrared stealth performance improvement have certain limitations. Therefore, developing a material with temperature control and low infrared emission to process and modify the leather is an effective way to prepare high-efficiency infrared stealth leather materials.

[0003] The phase change microcapsule is a new type of energy storage material with core-shell structure formed by coating the phase change material with high molecular polymer or inorganic material. The encapsulation technology not only avoids the direct contact of the phase change material with the outside world, but also solves the problems of easy leakage and phase separation of the phase change material, expands the application field of the phase change energy storage technology, and has great market potential and broad application prospect in energy storage, heat management, infrared stealth and the like. According to the temperature control and low infrared emission principle of infrared stealth, the nanometer phase change capsule is synthesized by using the inorganic semiconductor or conductive polymer or organic-inorganic hybrid material with low infrared emission as the wall, and the temperature control performance and low infrared emission wall of the phase change material are used to synergistically enhance the infrared stealth effect.

[0004] The purpose of the present application is to provide a preparation method of infrared stealth leather based on phase change microcapsules, which solves the problem that the infrared stealth leather in the prior art cannot control the temperature.

[0005] The technical scheme adopted by the present application is a preparation method of infrared stealth leather based on phase change microcapsules, which specifically comprises the following steps:

[0006] Step 1, take the phase change material, deionized water and tetraethyl orthosilicate into a three-necked flask, dissolve cetyltrimethylammonium bromide in anhydrous ethanol, pour the cetyltrimethylammonium bromide solution into the three-necked flask, heat in a constant temperature water bath, and continuously stir to form a phase change emulsion; add ammonia water into the three-necked flask, keep constant temperature water bath heating, reduce the stirring speed and continuously stir, wash and filter with anhydrous ethanol, dry in an oven, and obtain phase change microcapsules of SiO2 coated phase change material;

[0007] Step 2, disperse the phase change microcapsules of phase change material coated with SiO2 in a PVP aqueous solution, ultrasonic dispersion and magnetic stirring, add nano-ZnO, continue magnetic stirring and centrifugal drying to obtain phase change microcapsules of phase change material@SiO2 / ZnO;

[0008] Step 3, ultrasonic dispersion of the phase change microcapsules of phase change material@SiO2 / ZnO in anhydrous ethanol to obtain a phase change microcapsule dispersion, add the phase change microcapsule dispersion to a polyurethane emulsion, continuously stir the polyurethane emulsion during the dropping process, and ultrasonic treatment after the dropping is completed to obtain a phase change microcapsule-polyurethane composite coating emulsion of phase change material@SiO2 / ZnO;

[0009] Step 4, coating the phase change microcapsule-polyurethane composite coating emulsion of phase change material@SiO2 / ZnO obtained in step 3 on the surface of the leather in batches to obtain infrared stealth leather.

[0010] The application also has the characteristics that:

[0011] In step 1, the phase change material includes at least one of paraffin, eicosane or docosane.

[0012] In step 1, the mass ratio of the phase change material to tetraethyl orthosilicate is 1:1~2:1, and the mass ratio of deionized water to anhydrous ethanol is 2:1~1:2, and the mass of cetyltrimethylammonium bromide is 0.3%~0.7% of the total mass of deionized water and anhydrous ethanol.

[0013] In step 1, the concentration of ammonia water is 25%, and the amount added is 1.5%~3% of the total mass of deionized water and anhydrous ethanol.

[0014] In step 2, the mass ratio of the phase change microcapsules of phase change material coated with SiO2 to nano-ZnO is 1:0.5~1:2.

[0015] In step 2, the concentration of the PVP aqueous solution is 1g / L, and the mass ratio of the PVP aqueous solution to the phase change microcapsules of phase change material coated with SiO2 is 200:1~500:1.

[0016] In step 1, the stirring is carried out by using an electric stirrer;

[0017] After the cetyltrimethylammonium bromide solution is poured into the three-necked flask, the speed of the electric stirrer is 1000rpm~3000rpm, and the continuous stirring time is 2~3h;

[0018] After the ammonia water is added to the three-necked flask, the speed of the electric stirrer is reduced to 300rpm~700rpm, and the continuous stirring time is 3~7h;

[0019] In step 1, the temperature of the constant temperature water bath heating is 60℃~80℃, and the oven temperature is 40℃.

[0020] In step 2, the ultrasonic dispersion and magnetic stirring time is 0.5h~1h; the nano-ZnO is added, and the magnetic stirring time is continued for 1h~2h.

[0021] In step 3, the ultrasonic treatment time is 10min;

[0022] In step 3, the mass ratio of the phase change material@SiO2 / ZnO phase change microcapsule to anhydrous ethanol is 0.1:10~0.1:25;

[0023] In step 3, the mass ratio of the phase change material@SiO2 / ZnO phase change microcapsule to the polyurethane emulsion is 1:10~1:50.

[0024] In step 4, the multiple coating is performed, and after each coating is completed, the coating is dried in a 100℃ oven for 5min before the next coating is performed.

[0025] The present application has the following beneficial effects:

[0026] 1. The present application adopts the temperature-controlled and low-infrared-emission phase change microcapsule, realizes high-efficiency infrared stealth through the synergistic effect of the phase change heat regulation ability of the microcapsule core phase change material and the low-infrared-emission rate of the shell layer, and constructs the infrared stealth leather by coating the polyurethane on the surface of the leather in a brushing manner.

[0027] 2. The infrared stealth leather prepared by the present application has the effect of infrared stealth, improves the functionality of the leather, and expands the application of the leather in the military field. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the scanning electron microscope image of the phase change microcapsule in the preparation method of the present application;

[0029] Figure 2 is the differential scanning calorimeter endothermic curve of the phase change microcapsule in the preparation method of the present application;

[0030] Figure 3 is the differential scanning calorimeter exothermic curve of the phase change microcapsule in the preparation method of the present application;

[0031] Figure 4 is the scanning electron microscope image of the surface of the leather in the prior art;

[0032] Figure 5 is the scanning electron microscope image of the surface of the infrared stealth leather in the preparation method of the present application;

[0033] Figure 6 is the thermal image of the leather in the prior art placed on the palm;

[0034] Figure 7The infrared stealth leather prepared by the method has a thermal image diagram of palm placement. DETAILED DESCRIPTION

[0035] The application will be described in detail below in combination with the drawings and specific embodiments.

[0036] The application provides a preparation method of infrared stealth leather based on phase change microcapsules, and specifically comprises the following steps:

[0037] Step 1: A phase change material, deionized water and tetraethyl orthosilicate are poured into a three-necked flask, cetyltrimethylammonium bromide is dissolved in anhydrous ethanol, the cetyltrimethylammonium bromide solution is poured into the three-necked flask, constant temperature water bath heating is performed, and continuous stirring is carried out to form a phase change emulsion; ammonia is added to the three-necked flask, constant temperature water bath heating is maintained, the stirring speed is reduced and continuous stirring is carried out, anhydrous ethanol is used for washing and filtering, and drying is performed in an oven to obtain phase change microcapsules of the SiO2 coated phase change material;

[0038] The phase change material is used to obtain the thermal regulation performance of the phase change microcapsules by phase transition through heat absorption or heat release, and the type or combination of the phase change material can be selected according to the required phase change temperature. In step 1 of the application, the phase change material includes at least one of paraffin, eicosane or docosane. The tetraethyl orthosilicate is used as a precursor of the SiO2 shell layer, and is polycondensed to generate the SiO2 shell under the action of ammonia to wrap the phase change material, which can prevent the leakage of the phase change material during solid-liquid phase transition and reduce the infrared emissivity of the phase change microcapsules. In step 1 of the application, the mass ratio of the phase change material to the tetraethyl orthosilicate is 1:1~2:1. The phase change microcapsules prepared by the mass ratio of 1:1~2:1 of the phase change material to the tetraethyl orthosilicate have a relatively large core-shell ratio, which ensures that more phase change materials are coated to have a relatively high phase change latent heat, so that the application of the phase change microcapsules in the leather coating still has the thermal regulation ability. The mass ratio of the deionized water to the anhydrous ethanol is 2:1~1:2, the mass of the cetyltrimethylammonium bromide is 0.3%~0.7% of the total mass of the deionized water and the anhydrous ethanol, the concentration of the ammonia is 25%, the addition amount of the ammonia is 1.5%~3% of the total mass of the deionized water and the anhydrous ethanol, the concentration of the PVP aqueous solution is 1g / L, the mass ratio of the PVP aqueous solution to the phase change microcapsules of the SiO2 coated phase change material is 200:1~500:1, the stirring is performed by using an electric stirrer, the stirring speed of the electric stirrer is 1000rpm~3000rpm after the cetyltrimethylammonium bromide solution is poured into the three-necked flask, the continuous stirring time is 2~3h, the stirring speed of the electric stirrer is reduced to 300rpm~700rpm after the ammonia is added to the three-necked flask, the continuous stirring time is 3~7h, the temperature of the constant temperature water bath heating is 60℃~80℃, and the oven temperature is 40℃.

[0039] The step 1 is to prepare the phase change microcapsule with phase change heat regulation and low infrared emission by using the interfacial polymerization method. The principle of the preparation of the phase change microcapsule with SiO2 coated phase change material by using the interfacial polymerization method is that: the oil phase mainly containing the phase change material, the water phase composed of ethanol and water, and tetraethyl orthosilicate are stirred at high speed to form the oil-in-water emulsion micelles under the action of the emulsifier cetyltrimethylammonium bromide, and then ammonia is added to hydrolyze and polymerize the tetraethyl orthosilicate to form SiO2, so as to obtain the phase change microcapsule with SiO2 coated phase change material. The phase change microcapsule with SiO2 coated phase change material prepared by using the interfacial polymerization method has the advantages that: the method for preparing the phase change microcapsule is simple, and the phase change microcapsule prepared has a small particle size, which is beneficial to the introduction of a large amount of the phase change microcapsule into the polyurethane coating matrix in the later stage, so as to obtain the infrared stealth leather.

[0040] In step 2, the phase change microcapsule with SiO2 coated phase change material is dispersed in the PVP aqueous solution containing the phase change material, ultrasonic dispersion and magnetic stirring are performed, nano-ZnO is added, and then centrifugal drying is performed after continuous magnetic stirring, so as to obtain the phase change material@SiO2 / ZnO phase change microcapsule; the ultrasonic dispersion and magnetic stirring time is 0.5 h to 1 h; the nano-ZnO is added, and the continuous magnetic stirring time is 1 h to 2 h. The nano-ZnO is a semiconductor with photocatalytic effect and has low infrared emissivity. The nano-ZnO acts as the shell material of the phase change microcapsule, can reduce the infrared emissivity of the phase change microcapsule, and improve the infrared stealth effect. In step 2, the mass ratio of the phase change microcapsule with SiO2 coated phase change material to the nano-ZnO is 1:0.5 to 1:2, and the ZnO is excessive. After a part of the ZnO is adsorbed on the surface of the SiO2 shell, the excessive ZnO exists in the form of free combination with the phase change microcapsule. The ZnO in different forms can reduce the infrared emissivity of the phase change microcapsule, so as to improve the infrared stealth performance of the phase change microcapsule.

[0041] The function of the step 2 of modifying the shell layer of the phase change microcapsule by using the nano-ZnO with low infrared emission is to further reduce the infrared emissivity of the phase change microcapsule and improve the infrared stealth performance. The principle of modifying the shell layer of the phase change microcapsule by using the nano-ZnO with low infrared emission is that: the phase change microcapsule with SiO2 coating is dispersed in the PVP solution, the purpose is to improve the affinity of the phase change microcapsule with the hydrophilic nano-ZnO particles, increase the adsorption amount of the nano-ZnO on the SiO2 shell, and on the other hand, the unadsorbed nano-ZnO is mixed with the phase change microcapsule. This method is simple in preparation, and a large amount of nano-ZnO can be introduced, so as to reduce the infrared emissivity. The advantage of modifying the shell layer of the phase change microcapsule by using the nano-ZnO with low infrared emission is that: the nano-ZnO is combined with the phase change microcapsule with SiO2 coating in a physical way.

[0042] Step 3, disperse the phase change material @ SiO2 / ZnO phase change microcapsule in anhydrous ethanol by ultrasonic to obtain a phase change microcapsule dispersion, add the phase change microcapsule dispersion into the polyurethane emulsion, continuously stir the polyurethane emulsion during the dropping process, and then ultrasonic treatment after the dropping is completed to obtain a phase change material @ SiO2 / ZnO phase change microcapsule-polyurethane composite coating emulsion; in step 3, the ultrasonic treatment time is 10 min; the mass ratio of the phase change material @ SiO2 / ZnO phase change microcapsule to anhydrous ethanol is 0.1:10-0.1:25; and the mass ratio of the phase change material @ SiO2 / ZnO phase change microcapsule to the polyurethane emulsion is 1:10-1:50, because the phase change microcapsule can be stably dispersed in the polyurethane emulsion, and the phase change microcapsule can play the phase change heat regulation performance and infrared stealth effect when coated on the surface of the leather.

[0043] The polyurethane emulsion is a kind of leather coating material, which acts as a matrix of the phase change capsule and is coated on the surface of the leather together with the phase change capsule to increase the amount of the phase change capsule introduced so as to better play the heat regulation performance of the phase change capsule and obtain the infrared stealth leather.

[0044] Step 4, coat the phase change material @ SiO2 / ZnO phase change microcapsule-polyurethane composite coating emulsion obtained in step 3 on the surface of the leather in batches to obtain the infrared stealth leather. The coating in batches means that after each coating is completed, the coated leather is dried in a 100℃ oven for 5 min and then the next coating is carried out. The function of step 4 is to coat the phase change microcapsule on the surface of the leather after the phase change microcapsule is combined with the polyurethane coating organic matrix to obtain the infrared stealth leather. The principle of coating the phase change microcapsule on the surface of the leather after the phase change microcapsule is combined with the polyurethane coating organic matrix is that the phase change microcapsule is first dispersed in anhydrous ethanol to wet the surface of the phase change microcapsule and increase the affinity with the polyurethane matrix, then the ethanol dispersion of the phase change microcapsule is slowly poured into the polyurethane emulsion, and the purpose of stirring while adding is to prevent the agglomeration of the phase change microcapsule, and continuous stirring further promotes the uniform dispersion of the phase change microcapsule particles in the polyurethane to obtain the phase change microcapsule-polyurethane composite coating emulsion; the phase change microcapsule-polyurethane composite coating emulsion is brushed and coated multiple times in order to uniformly coat a sufficient amount of phase change microcapsule on the surface of the leather to more efficiently play the infrared stealth performance. The advantages of coating the phase change microcapsule on the surface of the leather after the phase change microcapsule is combined with the polyurethane coating organic matrix are that this method does not change the conventional coating process of the leather, the operation is simple, and the phase change microcapsule is combined with the polyurethane coating organic matrix, which has the advantages of good combination of the phase change microcapsule and the polyurethane organic coating matrix, increased bonding strength of the phase change microcapsule, and the infrared stealth effect can be controlled according to the amount of the microcapsule introduced in the polyurethane and the number of brushing times.

[0045] The structure and performance of the phase change microcapsule and the infrared stealth leather prepared according to the present application are tested, and the results are as follows:

[0046] Figure 1 is a scanning electron micrograph of the phase change microcapsule prepared in the present application, as shown in Figure 1 It can be seen that the prepared phase change microcapsule is in the form of a complete sphere, with a particle size of about 1 mu m or so, and there are ZnO particles on the surface of the microcapsule, and the phase change microcapsule is successfully prepared, and the particle size is smaller than that of the conventional microcapsule, and the small particle size microcapsule will be beneficial to dispersion in the polyurethane coating layer;

[0047] Figure 2 The endothermic curve of the phase change microcapsule prepared in the present application is shown in Figure 2 It can be seen from the figure that the phase change temperature of the prepared phase change microcapsule in the endothermic process is basically the same as that of paraffin, and has very good latent heat of phase change, indicating that it has heat regulation performance;

[0048] Figure 3 The exothermic curve of the phase change microcapsule prepared in the present application is shown in Figure 3 It can be seen from the figure that the phase change temperature of the prepared phase change microcapsule in the exothermic process is basically the same as that of paraffin, and has very good latent heat of phase change, indicating that it has heat regulation performance;

[0049] Figure 4 The scanning electron micrograph of the surface of the original leather is shown in Figure 4 It can be seen that the collagen fiber texture on the surface of the original leather is obvious;

[0050] Figure 5 The scanning electron micrograph of the surface of the infrared stealth leather based on the phase change microcapsule prepared in the present application is shown in Figure 5 It can be seen that after the polyurethane composite coating of the phase change microcapsule is coated, obvious convex particles appear on the surface of the leather, which are the phase change microcapsule;

[0051] Figure 6 The thermal image of the original leather placed in the palm is shown in Figure 6 It can be seen from the figure that the temperature of the original leather is obviously increased after being placed in the palm for 120s;

[0052] Figure 7 The thermal image of the infrared stealth leather based on the phase change microcapsule prepared in the present application placed in the palm is shown in Figure 7 It can be seen from the figure that compared with the original leather, the temperature of the leather coated with the phase change microcapsule polyurethane composite coating is obviously lower when placed in the palm for the same time of 120s, indicating that it has good heat regulation capacity, i.e. infrared stealth performance.

[0053] Example 1

[0054] The preparation method of the infrared stealth leather based on the phase change microcapsule of the present application is specifically implemented according to the following steps:

[0055] Step 1, 2 g of phase change material, 15-35 g of deionized water and 2-3 g of tetraethyl orthosilicate were poured into a three-necked flask, 0.05-0.1 g of cetyltrimethylammonium bromide was dissolved in 15-35 g of anhydrous ethanol, the cetyltrimethylammonium bromide solution was poured into the three-necked flask, and the three-necked flask was placed in a constant temperature water bath at 60-80°C for heating, an electric stirrer was used to stir at a speed of 1000-3000 r / min for 2-3 h to form a phase change emulsion. 0.5-2 mL of ammonia water was slowly added to the three-necked flask, the temperature was kept unchanged, the stirring speed was reduced to 300-700 r / min, and the stirring was continued for 3-7 h, then the product was washed and filtered with anhydrous ethanol, and dried in a 40°C oven to obtain phase change microcapsules coated with SiO2 and phase change material;

[0056] Step 2, 0.1 g of phase change microcapsules coated with SiO2 and phase change material were dispersed in a solution containing 20-50 g of PVP water solution, the concentration of the PVP water solution was 1 g / L, ultrasonic dispersion and magnetic stirring were performed for 0.5-1 h, 0.05-0.2 g of nano-ZnO was added, and magnetic stirring was continued for 1-2 h, then centrifugal drying was performed to obtain phase change material@SiO2 / ZnO phase change microcapsules;

[0057] Step 3, 0.2 g of phase change material@SiO2 / ZnO phase change microcapsules were dispersed in 2-5 mL of anhydrous ethanol to obtain a phase change microcapsule dispersion, the dispersion was slowly added to 2-10 g of a polyurethane emulsion, the polyurethane emulsion was continuously stirred during the dropwise addition, ultrasonic treatment was performed for 10 min after the addition was completed, and a phase change material@SiO2 / ZnO phase change microcapsule-polyurethane composite coating emulsion was obtained;

[0058] Step 4, the composite coating emulsion was coated on the surface of the leather by brushing, and each coating was dried in a 100°C oven for 5 min before the next coating, and an infrared stealth leather was obtained.

[0059] The prepared phase change capsules had a particle size of about 1 μm, as shown in FIG. 1, the nano-ZnO particles were successfully adsorbed on the surface of the SiO2 of the microcapsules, and the paraffin@SiO2 / ZnO phase change capsules were successfully obtained; in the DSC heating and cooling process, the phase change microcapsules had obvious endothermic and exothermic peaks, as shown in FIGS. 2 and 3, and the phase change temperature was basically consistent with that of paraffin, indicating that the paraffin was successfully coated in the SiO2 / ZnO shell and showed temperature control performance. Figure 1 Figure 2 Figure 3 The surface of the original leather without coating had obvious collagen fibers and micro-pores, as shown in FIG. 4, the surface of the leather coated with polyurethane and phase change capsules was rough and had small phase change capsule particles, as shown in FIG. 5, and the infrared thermal image of the original leather was visible, as shown in FIG. 6.

[0060] Figure 4 Figure 5 Figure 6 ​​​​​As shown, the temperature of the leather increases faster after palm placement 120, while the leather coated with polyurethane and phase change capsules is still blue after palm placement 120, as shown Figure 7 As shown, it is shown that its temperature is low, indicating that the leather coated with phase change capsules has obvious temperature control performance, that is, has infrared stealth effect.

[0061] Example 2

[0062] The preparation method of the infrared stealth leather based on phase change microcapsules is implemented according to the following steps:

[0063] Step 1, take 25 mL of deionized water and 2 mL of ethyl silicate into a three-necked flask, take 2 g of paraffin and 0.08 g of hexadecyl trimethyl ammonium bromide into the three-necked flask and a beaker containing 25 mL of anhydrous ethanol, respectively, mix them, after melting, pour the liquid in the beaker into the three-necked flask, put it into a 60℃ constant temperature water bath for heating, use an electric stirrer to stir at high speed for 3h, 1500r / min, form a phase change emulsion. Add 0.6 mL of ammonia water to keep the heating temperature of the phase change emulsion unchanged, reduce the stirring speed to 700r / min, continue to stir for 3h, wash and filter with anhydrous ethanol, dry in a 40℃ oven, and obtain phase change microcapsules coated with SiO2 and phase change materials;

[0064] Step 2, disperse 0.1 g of the phase change microcapsules in 20 mL of PVP aqueous solution, the concentration of the PVP aqueous solution is 1g / L, ultrasonic dispersion for 20 min and magnetic stirring for 0.5h, add 0.05 g of nano ZnO, continue to stir for 2h, and obtain phase change material@SiO2 / ZnO phase change microcapsules;

[0065] Step 3, disperse 0.2 g of phase change material@SiO2 / ZnO phase change microcapsules in 2 mL of anhydrous ethanol to obtain a phase change microcapsule dispersion, slowly drop the dispersion into 5 g of polyurethane emulsion, continue to stir the polyurethane emulsion during the dropping process, ultrasonic for 10 min after dropping, and obtain a phase change microcapsule-polyurethane composite coating emulsion;

[0066] Step 4, use brushing method to coat it on the surface of the leather, coat 3 times, dry in a 100℃ oven for 5 min after each coating, and then coat the next time, and obtain infrared stealth leather.

[0067] Example 3

[0068] The preparation method of the infrared stealth leather based on phase change microcapsules is implemented according to the following steps:

[0069] Step 1, 25 mL of deionized water and 2 mL of tetraethyl orthosilicate are poured into a three-necked flask, 3 g of paraffin and 0.08 g of cetyltrimethylammonium bromide are added into the three-necked flask and a beaker containing 25 mL of anhydrous ethanol respectively, after the two are melted, the liquid in the beaker is poured into the three-necked flask, and heated in a 60℃ constant temperature water bath, high-speed stirring is carried out with an electric stirrer for 2 h, 1500 r / min, and a phase change emulsion is formed. 0.6 mL of ammonia water is added to keep the heating temperature of the phase change emulsion unchanged, and the stirring speed is reduced to 300 r / min, and the stirring is continued for 3 h, and then washed, filtered and dried in a 40℃ oven to obtain phase change microcapsules coated with SiO2 and phase change materials;

[0070] Step 2, the 0.1 g of phase change microcapsules are dispersed in 20 mL of PVP aqueous solution, the concentration of PVP aqueous solution is 1 g / L, ultrasonic dispersion is carried out for 20 min and magnetic stirring is carried out for 0.5 h, 0.05 g of nano-ZnO is added, and magnetic stirring is continued for 2 h to obtain phase change material@SiO2 / ZnO phase change microcapsules;

[0071] Step 3, 0.2 g of phase change material@SiO2 / ZnO phase change microcapsules are dispersed in 2 mL of anhydrous ethanol to obtain a phase change microcapsule dispersion liquid, the dispersion liquid is slowly added into 5 g of polyurethane emulsion, the polyurethane emulsion is continuously stirred during the dropwise addition process, and ultrasonic treatment is carried out for 10 min to obtain a phase change microcapsule-polyurethane composite coating emulsion;

[0072] Step 4, the phase change microcapsule-polyurethane composite coating emulsion is coated on the surface of the leather by brushing, and the coating is carried out for 3 times, and after each coating, the coated leather is dried in a 100℃ oven for 5 min and then the next coating is carried out, to obtain infrared stealth leather.

[0073] Example 4

[0074] The preparation method of the infrared stealth leather based on phase change microcapsules is carried out according to the following steps:

[0075] Step 1, 25 mL of deionized water and 2 mL of tetraethyl orthosilicate are poured into a three-necked flask, 3 g of paraffin and 0.08 g of cetyltrimethylammonium bromide are added into the three-necked flask and a beaker containing 25 mL of anhydrous ethanol respectively, after the two are melted, the liquid in the beaker is poured into the three-necked flask, and heated in a 60℃ constant temperature water bath, high-speed stirring is carried out with an electric stirrer for 2 h, 1500 r / min, and a phase change emulsion is formed. 0.6 mL of ammonia water is added to keep the heating temperature of the phase change emulsion unchanged, and the stirring speed is reduced to 300 r / min, and the stirring is continued for 3 h, and then washed, filtered and dried in a 40℃ oven to obtain phase change microcapsules coated with SiO2 and phase change materials;

[0076] Step 2, 0.1 g of the phase change microcapsules were dispersed in 20 mL of a PVP aqueous solution with a PVP concentration of 1 g / L, ultrasonic dispersion was performed for 20 min and magnetic stirring was performed for 0.5 h, 0.2 g of nano-ZnO was added, magnetic stirring was continuously performed for 2 h, and phase change material@SiO2 / ZnO phase change microcapsules were obtained;

[0077] Step 3: 0.2 g of the phase change material@SiO2 / ZnO phase change microcapsules were dispersed in 2 mL of anhydrous ethanol to obtain a phase change microcapsule dispersion liquid, the dispersion liquid was slowly added dropwise into 5 g of a polyurethane emulsion, stirring of the polyurethane emulsion was continuously performed during the dropwise addition process, ultrasonic dispersion was performed for 10 min after the addition was completed, and a phase change microcapsule-polyurethane composite coating emulsion was obtained;

[0078] Step 4: The phase change microcapsule-polyurethane composite coating emulsion was coated on the surface of the leather by brushing, 3 times of coating were performed, and the leather was dried in a 100℃ oven for 5 min after each coating and before the next coating, and infrared stealth leather was obtained.

[0079] Example 5

[0080] The present application discloses a preparation method of infrared stealth leather based on phase change microcapsules, and the method is implemented according to the following steps:

[0081] Step 1: 25 mL of deionized water and 2 mL of tetraethyl orthosilicate were poured into a three-necked flask, 3 g of docosane and 0.08 g of hexadecyltrimethylammonium bromide were added into the three-necked flask and a beaker containing 25 mL of anhydrous ethanol respectively, the liquid in the beaker was poured into the three-necked flask after the two were melted, and the three-necked flask was placed in a 60℃ constant-temperature water bath for heating, and an electric stirrer was used for high-speed stirring for 2 h at 1500 r / min, to form a phase change emulsion. 0.6 mL of ammonia water was added to keep the heating temperature of the phase change emulsion unchanged, and the stirring speed was reduced to 500 r / min, and the stirring was continuously performed for 3 h, and the phase change emulsion was washed and filtered with anhydrous ethanol, and was dried in a 40℃ oven, to obtain phase change microcapsules coated with SiO2 and phase change materials;

[0082] Step 2, 0.1 g of the phase change microcapsules were dispersed in 20 mL of a PVP aqueous solution with a PVP concentration of 1 g / L, ultrasonic dispersion was performed for 20 min and magnetic stirring was performed for 0.5 h, 0.2 g of nano-ZnO was added, magnetic stirring was continuously performed for 2 h, and phase change material@SiO2 / ZnO phase change microcapsules were obtained;

[0083] Step 3: 0.5 g of the phase change material@SiO2 / ZnO phase change microcapsules were dispersed in 5 mL of anhydrous ethanol to obtain a phase change microcapsule dispersion liquid, the dispersion liquid was slowly added dropwise into 5 g of a polyurethane emulsion, stirring of the polyurethane emulsion was continuously performed during the dropwise addition process, ultrasonic dispersion was performed for 10 min after the addition was completed, and a phase change microcapsule-polyurethane composite coating emulsion was obtained;

[0084] Step 4, the coating was applied to the surface of the leather by brush coating, 3 times, and after each coating, the coating was dried in an oven at 100°C for 5 min before the next coating, to obtain the infrared stealth leather.

Claims

1. A method for preparing infrared stealth leather based on phase change microcapsules, characterized in that, Specifically, the following steps are included: Step 1: Pour the phase change material, deionized water, and tetraethyl orthosilicate into a three-necked flask. Separately, dissolve hexadecyltrimethylammonium bromide in anhydrous ethanol. Pour the hexadecyltrimethylammonium bromide solution into the three-necked flask, heat in a constant temperature water bath, and stir continuously to form a phase change emulsion. Add ammonia water to the three-necked flask, maintain constant temperature water bath heating, reduce the stirring speed, and continue stirring. Wash and filter with anhydrous ethanol, and dry in an oven to obtain SiO2-coated phase change microcapsules of the phase change material. Step 2: Disperse the SiO2-coated phase change material microcapsules in an aqueous solution containing PVP, ultrasonically disperse and magnetically stir, add nano-ZnO, continue magnetic stirring and centrifuge to dry, and obtain phase change material @SiO2 / ZnO phase change microcapsules; Step 3: Disperse the phase change material @SiO2 / ZnO phase change microcapsules in anhydrous ethanol and sonicate to obtain a phase change microcapsule dispersion. Add the phase change microcapsule dispersion to a polyurethane emulsion and continuously stir the polyurethane emulsion during the dropwise addition process. After the dropwise addition is completed, perform ultrasonic treatment to obtain a phase change material @SiO2 / ZnO phase change microcapsule-polyurethane composite coating emulsion. Step 4: Apply the phase change material @SiO2 / ZnO phase change microcapsule-polyurethane composite coating emulsion obtained in Step 3 to the leather surface in multiple coats to obtain infrared stealth leather. In step 1, the mass ratio of phase change material to tetraethyl orthosilicate is 1:1 to 2:1, the mass ratio of deionized water to anhydrous ethanol is 2:1 to 1:2, and the mass of hexadecyltrimethylammonium bromide is 0.3% to 0.7% of the total mass of deionized water and anhydrous ethanol.

2. The method for preparing infrared stealth leather based on phase change microcapsules according to claim 1, characterized in that, In step 1, the phase change material includes at least one of paraffin, eicosane, or docosane.

3. The method for preparing infrared stealth leather based on phase change microcapsules according to claim 1, characterized in that, In step 1, the ammonia concentration is 25%, and the amount added is 1.5% to 3% of the total mass of deionized water and anhydrous ethanol.

4. The method for preparing infrared stealth leather based on phase change microcapsules according to claim 1, characterized in that, In step 2, the mass ratio of SiO2-coated phase change microcapsules to nano-ZnO is 1:0.5 to 1:

2.

5. The method for preparing infrared stealth leather based on phase change microcapsules according to claim 1, characterized in that, In step 2, the concentration of the PVP aqueous solution is 1 g / L, and the mass ratio of the PVP aqueous solution to the SiO2-coated phase change microcapsules is 200:1-500:

1.

6. The method for preparing infrared stealth leather based on phase change microcapsules according to claim 1, characterized in that, In step 1, the stirring is performed using an electric stirrer; After pouring the hexadecyltrimethylammonium bromide solution into a three-necked flask, the electric stirrer was set to 1000 rpm to 3000 rpm and stirred continuously for 2 to 3 hours. After adding ammonia water to the three-necked flask, the speed of the electric stirrer is reduced to 300 rpm to 700 rpm, and the stirring time is 3 to 7 hours. In step 1, the temperature of the constant temperature water bath is 60℃~80℃, and the temperature of the drying oven is 40℃.

7. The method for preparing infrared stealth leather based on phase change microcapsules according to claim 1, characterized in that, In step 2, the ultrasonic dispersion and magnetic stirring time is 0.5h~1h; after adding nano ZnO, the magnetic stirring time is continued for 1h~2h.

8. The method for preparing infrared stealth leather based on phase change microcapsules according to claim 1, characterized in that, In step 3, the ultrasonic treatment time is 10 minutes; In step 3, the mass ratio of the phase change material @SiO2 / ZnO phase change microcapsules to anhydrous ethanol is 0.1:10~0.1:25; In step 3, the mass ratio of the phase change material @SiO2 / ZnO phase change microcapsules to the polyurethane emulsion is 1:10 to 1:

50.

9. The method for preparing infrared stealth leather based on phase change microcapsules according to claim 1, characterized in that, In step 4, the coating is applied in multiple coats, which means that after each coat is applied, the product is dried in an oven at 100°C for 5 minutes before the next coat is applied.

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