Disclosure of Invention
In order to overcome the defects of the prior art, the invention takes the organic silazane polymer resin as the shell material of the phase-change energy-storage microcapsule, takes the n-alkane phase-change material as the core material of the phase-change energy-storage microcapsule, and adopts the interfacial polymerization method to prepare the phase-change energy-storage microcapsule taking the organic silazane polymer resin as the shell material. In order to achieve the purpose of the invention, the invention adopts the following technical scheme. The organic silazane polymer resin is used as a shell material and applied to the phase-change energy-storage microcapsule, and the phase-change energy-storage microcapsule prepared by the interfacial polymerization method can keep the excellent performances of compactness, mechanical strength, heat resistance and the like of the microcapsule on the premise of ultrathin shell material, makes up the defects of the phase-change energy-storage microcapsule prepared by the interfacial polymerization method disclosed by the prior patent technology, and has important application value.
One aspect of the invention provides a preparation method of a phase change energy storage microcapsule taking an organic silazane polymer resin as a shell material, which comprises the following steps:
1) preparing a water phase: preparing an aqueous solution of an emulsifier to obtain a water phase;
2) preparing an oil phase: uniformly mixing silazane polymer, organic solvent, phase change energy storage material and catalyst to obtain an oil phase;
3) preparing an emulsion: mixing the water phase and the oil phase, and obtaining an oil-in-water emulsion by mechanical dispersion;
4) and heating the emulsion to 55-75 ℃, adding a catalyst, heating to 80-95 ℃, and keeping the temperature constant to obtain the phase change energy storage microcapsule with the organic silazane polymer resin shell.
In the technical scheme of the invention, the emulsifier is selected from an oil-in-water emulsifier, preferably the emulsifier has an HLB value of 8-15, more preferably, the emulsifier is styrene maleic anhydride copolymer sodium salt, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, OP-10, Tween 80, cocamidopropyl dimethyl aminoethylenolactone, polyoxyethylene (16) sorbitan monolaurate, polyoxyethylene (10) sorbitan monolaurate, polyoxyethylene (20) sorbitan dioleate, sodium abietate, C14-18 sodium alkyl sulfate, dialkyl sulfosuccinate or a compound thereof.
In the technical scheme of the invention, the concentration of the emulsifier in the water phase in the step 1) is 1-10%, preferably 2.5-6.0%, and more preferably 4-5%.
In the technical scheme of the invention, the ratio of the silazane polymer to the phase change energy storage material in the step 2) is 1:2-1:5, preferably 1:2.8-1: 4.5.
In the technical scheme of the invention, the phase change energy storage material is selected from one or more of n-alkanes, preferably, the n-alkanes are tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heneicosane, docosane, tricosane, tetracosane, pentacosane and hexacosane.
In the technical scheme of the invention, the organic solvent in the step 2) is selected from organic solvents capable of dissolving silazane polymers, and preferably ethyl acetate, butyl acetate, acetone, cyclohexanone, toluene and xylene.
In the technical scheme of the invention, the catalyst in the steps 2) and 3) is selected from a platinum (0) -divinyl tetramethyl disiloxane compound and an organic tin catalyst, preferably, the organic tin catalyst is dibutyltin dilaurate, stannous octoate, dibutyltin didodecyl sulfide, dibutyltin diacetate, dibutyltin dichloride, methyltin trichloride, trimethyltin chloride, dibutyltin didecanate, zinc isooctanoate and bismuth neodecanoate.
In the technical scheme of the invention, the catalyst is added in the step 2) in an amount of silazane polymer: the catalyst is 1:0.001-0.005, preferably 1: 0.001-0.003.
In the technical scheme of the invention, the catalyst is added in the step 3) in an amount of silazane polymer: the catalyst is 1:0.002-0.01, preferably 1: 0.002-0.006.
In the technical scheme of the invention, the step 2) is carried out at the temperature of melting of the phase change energy storage material, preferably 20-50 ℃.
In the technical scheme of the invention, the step 3) is that the water phase is kept warm for 5-30 minutes at 55-75 ℃, the oil phase is added into the water phase, and the oil phase is dispersed at high speed to form stable oil-in-water type emulsion;
in another aspect, the invention provides a phase change energy storage microcapsule taking the organic silazane polymer resin prepared by the method as a shell material.
The invention also provides a phase change energy storage microcapsule taking an organic silazane polymer resin as a shell material, which comprises a shell of a silazane polymer and an inner core of a phase change energy storage material, wherein the phase change energy storage material is n-alkane; the mass ratio of the silazane polymer to the phase change energy storage material is 1:2-1: 5. Preferably, the n-alkane is tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heneicosane, docosane, tricosane, tetracosane, pentacosane or hexacosane.
In the technical scheme of the invention, the mass ratio of the silazane polymer to the phase change energy storage material is 1:2.8-1: 4.5.
In the technical scheme of the invention, the particle size of the phase change energy storage microcapsule is 300nm-100 μm.
The invention relates to a phase change energy storage microcapsule taking organic silazane polymer resin as a shell material, which comprises:
(1) preparing a water phase; uniformly mixing 4.0-65.0 g of emulsifier or emulsifier aqueous solution and 10.0-75.0 g of deionized water to obtain a water phase;
(2) mixing 5.0-15.0 g of organic silazane polymer and 10.0-40.0 g of ethyl acetate, stirring until the organic silazane polymer and the ethyl acetate are completely dissolved, adding 5.0-60.0 g of phase change energy storage material, completely dissolving at 20-50 ℃, adding 0.025-1.0 g of catalyst, stirring and uniformly mixing to prepare an oil phase;
(3) preserving the temperature of the water phase at 55-75 ℃ for 5-30 minutes, adding the oil phase into the water phase, and dispersing at a high speed of 1000-10000 rpm for 5-30 minutes to form a stable oil-in-water type emulsion;
(4) and (3) after the emulsion is subjected to heat preservation at the temperature of 55-75 ℃ for 15-30 minutes, dropwise adding 0.05-1.5 g of catalyst again, heating to the temperature of 80-95 ℃, and keeping the temperature for 2.0-6.0 hours to obtain the ultrathin phase change energy storage microcapsule with the organic silazane polymer resin shell.
The principle of the interfacial polymerization method applied by the invention is as follows:
the interfacial polymerization method is a method for preparing microcapsules by respectively dissolving two monomers or polymers with different hydrophilicity and hydrophobicity in an aqueous phase and an organic phase (oil phase) which are not mutually soluble, and after one phase of solution is dispersed into the other phase of solution (emulsification), the monomers in the two phases of solution are subjected to polymerization reaction at an oil-water interface. The interfacial polymerization has the advantages of high reaction speed, mild conditions, low requirements on monomer purity and proportion and the like. The invention takes water as a water-soluble reaction monomer, takes an organic silicon nitrogen alkane polymer as an oil-soluble reaction monomer, mainly takes hydrolysis and oxidation of Si-NH-Si bonds of the organic silicon nitrogen alkane polymer, adds a proper catalyst to promote the reaction of Si-H and Si-NH-Si, and forms the ultrathin superhard organic silicon nitrogen alkane polymer resin shell material with a three-dimensional cross-linked structure after curing.
The invention takes organic silazane polymer resin as a shell material and takes n-alkane phase change energy storage material as a core material, and utilizes an interfacial polymerization method to prepare the phase change energy storage microcapsule with the ultrathin organic silazane polymer resin shell. Wherein the water phase is emulsifier water solution and deionized water, and the oil phase is mixture of organic silazane polymer, ethyl acetate and phase-change energy storage material. And mixing the water phase and the oil phase, dispersing at a high speed to form emulsion, carrying out hydrolysis, oxidation and polycondensation addition reaction on the organic silazane polymer on a water-oil interface to form an organic silazane polymer resin shell, and coating the phase change energy storage material in the organic silazane polymer resin shell.
Advantageous effects
(1) The invention aims to solve the technical problem of providing a phase change energy storage microcapsule taking organic silazane polymer resin as a shell material and a preparation method thereof.
(2) The preparation method provided by the invention has the advantages of mild conditions and simple and easily-controlled process, and the prepared phase-change material microcapsule has the advantages of good sealing performance, high mechanical strength, high heat resistance and heat storage performance, good stability, and excellent performances of flexibility, organic solvent resistance, flame retardance (nonflammable), light transmittance (visible light transmittance: > 90%), ultraviolet resistance and the like.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, but the present invention is not to be construed as limiting the implementable range thereof.
In the invention, the organic silazane polymer is organic silicon polysilazane OPSZ-9150 produced by Anhui Eyota silicone oil Co.
Example 1 preparation of phase-change energy-storage microcapsules with organosilazane polymer resin as shell material
(1) Preparation of the aqueous phase
Weighing 60 g of 10% styrene maleic anhydride copolymer sodium salt (SMA-Na) aqueous solution in a beaker, adding deionized water to 100 g, stirring to completely dissolve an emulsifier, and adjusting the pH value with glacial acetic acid: 4.0-5.0, preparing a 5% emulsifier aqueous solution to obtain a water phase;
(2) preparation of oil phase
Adding 14 g of organic silazane polymer and 40 g of ethyl acetate into a beaker, mixing, stirring until complete mutual solubility, adding 60 g of n-docosane, completely dissolving at 20-30 ℃, adding 0.025 g of platinum (0) -divinyl tetramethyl disiloxane compound, and stirring and uniformly mixing to obtain an oil phase;
(3) formation of emulsions
Keeping the temperature of the water phase at 70 ℃ for 10 minutes, adding the oil phase into the water phase, and dispersing at a high speed of 2000rpm for 15 minutes to form a stable oil-in-water emulsion;
(4) formation of microcapsules
And after emulsification, reducing the rotating speed, adding 0.05 g of platinum (0) -divinyl tetramethyl disiloxane compound into the emulsion, preserving the temperature at 70 ℃ for 30 minutes, heating to 85 ℃, continuing to react for 4 hours to finish the reaction to obtain phase change energy storage microcapsule slurry with an ultrathin organic silazane polymer resin shell, diluting the slurry with a proper amount of deionized water, standing and aging for 48 hours, washing with the deionized water, filtering under reduced pressure to obtain a filter cake, and drying in a 70 ℃ drying oven for 5-8 hours to obtain the phase change energy storage microcapsule powder taking the organic silazane polymer resin with the particle size of 14-30 mu m (the average particle size is 26 mu m) as a shell material.
Example 2 preparation of phase-change energy-storage microcapsules with organosilazane polymer resin as shell material
(1) Preparation of the aqueous phase
Weighing 6 g of sodium dodecyl benzene sulfonate in a beaker, adding deionized water to 100 g, stirring to completely dissolve the emulsifier, and preparing into 6% emulsifier aqueous solution to obtain a water phase;
(2) preparation of oil phase
Adding 15 g of organic silazane polymer and 40 g of ethyl acetate into a beaker, mixing, stirring until the materials are completely mutually soluble, adding 60 g of n-octadecane, completely mutually dissolving at the temperature of 20-30 ℃, adding 0.03 g of stannous octoate, and stirring and uniformly mixing to prepare an oil phase;
(3) formation of emulsions
Keeping the temperature of the water phase at 70 ℃ for 10 minutes, adding the oil phase into the water phase, and dispersing at a high speed of 5000rpm for 15 minutes to form a stable oil-in-water emulsion;
(4) formation of microcapsules
And after emulsification, reducing the rotating speed, adding 0.05 g of stannous octoate into the emulsion, keeping the temperature at 70 ℃ for 30 minutes, heating to 85 ℃, continuing to react for 6 hours to finish the reaction to obtain the phase-change energy-storage microcapsule slurry with the ultrathin organic silazane polymer resin shell, diluting the slurry with a proper amount of deionized water, standing and aging for 48 hours, washing with the deionized water, filtering under reduced pressure to obtain a filter cake, and drying in a 70 ℃ drying oven for 5-8 hours to obtain the phase-change energy-storage microcapsule powder taking the organic silazane polymer resin with the particle size of 900 nm-2.4 mu m (the average particle size is 1.5 mu m) as a shell material.
Example 3 preparation of phase Change energy storage microcapsules with organosilazane Polymer resin as Shell Material
(1) Preparation of the aqueous phase
Weighing 60 g of 10% styrene maleic anhydride copolymer sodium salt (SMA-Na) aqueous solution in a beaker, adding deionized water to 100 g, stirring to completely dissolve an emulsifier, and adjusting the pH value with glacial acetic acid: 4.0-5.0, preparing a 5% emulsifier aqueous solution to obtain a water phase;
(2) preparation of oil phase
Adding 20 g of organic silazane polymer and 40 g of ethyl acetate into a beaker, mixing, stirring until complete mutual solubility, adding 60 g of n-hexadecane, completely mutual solubility at 20-30 ℃, adding 0.035 g of platinum (0) -divinyl tetramethyl disiloxane compound, and stirring and uniformly mixing to obtain an oil phase;
(3) formation of emulsions
Keeping the temperature of the water phase at 70 ℃ for 10 minutes, adding the oil phase into the water phase, and dispersing at a high speed of 1000rpm for 15 minutes to form a stable oil-in-water emulsion;
(4) formation of microcapsules
And after emulsification, reducing the rotating speed, adding 0.08 g of platinum (0) -divinyl tetramethyl disiloxane compound into the emulsion, keeping the temperature at 70 ℃ for 30 minutes, heating to 95 ℃, continuing to react for 6 hours to finish the reaction to obtain phase change energy storage microcapsule slurry with an ultrathin organic silazane polymer resin shell, diluting the slurry with a proper amount of deionized water, standing and aging for 48 hours, washing with the deionized water, carrying out reduced pressure filtration to obtain a filter cake, and drying in an oven at 70 ℃ for 5-8 hours to obtain the phase change energy storage microcapsule powder taking 240-560 nm (the average particle size is 510nm) organic silazane polymer resin as a shell material.
Example 4 preparation of phase Change energy storage microcapsules with Organosiloxazane Polymer resin as Shell Material
(1) Preparation of the aqueous phase
Weighing 4 g of sodium dodecyl sulfate in a beaker, adding deionized water to 100 g, stirring to completely dissolve an emulsifier, and preparing into a 4% emulsifier aqueous solution to obtain a water phase;
(2) preparation of oil phase
Adding 18 g of organic silazane polymer and 40 g of ethyl acetate into a beaker, mixing, stirring until complete mutual solubility, adding 60 g of n-eicosane, completely mutual solubility at 20-30 ℃, adding 0.035 g of dibutyltin dilaurate, and stirring and uniformly mixing to obtain an oil phase;
(3) formation of emulsions
Keeping the temperature of the water phase at 70 ℃ for 10 minutes, adding the oil phase into the water phase, and dispersing at 8000rpm for 15 minutes at a high speed to form a stable oil-in-water emulsion;
(4) formation of microcapsules
And after emulsification, reducing the rotating speed, adding 0.075 g of dibutyltin dilaurate into the emulsion, keeping the temperature at 70 ℃ for 30 minutes, heating to 90 ℃, continuing to react for 6 hours to finish the reaction to obtain the phase-change energy-storage microcapsule slurry with the ultrathin organic silazane polymer resin shell, diluting the slurry with a proper amount of deionized water, standing and aging for 48 hours, washing with the deionized water, filtering under reduced pressure to obtain a filter cake, and drying in a 70 ℃ drying oven for 5-8 hours to obtain the phase-change energy-storage microcapsule powder taking the organic silazane polymer resin with the particle size of 570-860 nm (the average particle size is 774nm) as a shell material.
Example 5 preparation of phase Change energy storage microcapsules with Organosiloxazane Polymer resin as Shell Material
(1) Preparation of the aqueous phase
Weighing 60 g of 10% styrene maleic anhydride copolymer sodium salt (SMA-Na) aqueous solution in a beaker, adding deionized water to 100 g, stirring to completely dissolve an emulsifier, and adjusting the pH value with glacial acetic acid: 4.0-5.0, preparing a 5% emulsifier aqueous solution to obtain a water phase;
(2) preparation of oil phase
Adding 14 g of organic silazane polymer and 40 g of ethyl acetate into a beaker, mixing, stirring until complete mutual solubility, adding 60 g of n-docosane, completely mutual solubility at 20-30 ℃, adding 0.03 g of platinum (0) -divinyl tetramethyl disiloxane compound, and stirring and uniformly mixing to obtain an oil phase;
(3) formation of emulsions
Keeping the temperature of the water phase at 70 ℃ for 10 minutes, adding the oil phase into the water phase, and dispersing at a high speed of 5500rpm for 15 minutes to form a stable oil-in-water emulsion;
(4) formation of microcapsules
And after emulsification, reducing the rotating speed, adding 0.06 g of platinum (0) -divinyl tetramethyl disiloxane compound into the emulsion, keeping the temperature at 70 ℃ for 30 minutes, heating to 85 ℃, continuing to react for 6 hours to finish the reaction to obtain the phase change energy storage microcapsule slurry with the ultrathin organic silazane polymer resin shell, diluting the slurry with a proper amount of deionized water, standing and aging for 48 hours, washing with the deionized water, filtering under reduced pressure to obtain a filter cake, and drying in a 70 ℃ drying oven for 5-8 hours to obtain the phase change energy storage microcapsule powder with the particle size of 480 nm-2.0 mu m (the average particle size is 1.1 mu m) and taking the organic silazane polymer resin as the shell material.
Effect example 1
Observing the appearance of the microcapsule as a spherical shape with smooth and compact surface by an optical microscope and a scanning electron microscope; the melting peak temperature of the microcapsule of the embodiment 1 of the invention is 44.56 ℃, the melting endothermic enthalpy is 200.0J/g, the crystallization exothermic enthalpy is 194.9J/g by differential scanning calorimetry, which shows that the microcapsule has higher heat storage capacity; the microcapsules of the invention example 1 have good stability at a temperature below 237.73 ℃ by thermogravimetric analysis.
Effect example 2 microcapsule mechanical Strength test
Ultrasonic wave is generated by an ultrasonic oscillator to generate high-frequency mechanical oscillation, ultrasonic waves are formed in a medium, and the ultrasonic waves are alternately radiated and transmitted forward in the medium at intervals by positive pressure and negative pressure high-frequency change, so that countless small bubbles are continuously generated in the medium and are continuously broken, namely, the cavitation effect is formed, so that a series of explosions are generated to release huge energy, huge impact is formed on the periphery, the surface of a microcapsule shell material is continuously impacted, and the microcapsule with weak mechanical strength is broken. Under the ultrasonic oscillation, samples are taken at intervals to carry out scanning electron microscope observation on the damage condition of the microcapsule sample, thereby achieving the purpose of testing the mechanical strength of the microcapsule.
Dispersing two kinds of microcapsule powder with the same mass into deionized water with the same mass, respectively filling into two conical flasks with the same specification, placing in an ultrasonic oscillator, ultrasonically oscillating, and sampling every 15 minutes to observe the damage condition of the microcapsule. And (3) testing results: (1) FIG. 8 is a scanning electron microscope image of a sample of phase change microcapsules with polyurea resin as shell material prepared by a commercially available interfacial polymerization method after 15 minutes of ultrasonic oscillation, wherein more than 50% of the microcapsules are broken. (2) Fig. 9 is a scanning electron microscope image of a phase change microcapsule sample (inventive example 5) prepared by interfacial polymerization method and using organic silazane polymer resin as a shell material, sampled after 30 minutes of ultrasonic oscillation, and almost no microcapsule rupture is observed.
Effect example 3 sealing Property test of microcapsules
By utilizing the characteristic that a polyurea resin shell material and an organic silazane polymer resin shell material of microcapsules are insoluble in absolute ethyl alcohol, and a core material of the microcapsules, namely n-docosane, is soluble in the ethyl alcohol and insoluble in the water, a certain amount of microcapsule samples can be soaked in the absolute ethyl alcohol, the mechanical stirring is carried out for 15 minutes, then water with twice of the ethyl alcohol is added, the stirring is continued for 15 minutes, the standing and the layering are carried out, upper layer microcapsule slurry is collected and is spread on oil absorption paper, the oil absorption paper is placed in an oven for drying at 70 ℃ for 2 hours, the samples are taken out, microcapsule powder of the oil absorption paper is blown off by an ear washing ball, and the oil stain condition of the oil. The method comprises the steps of dissolving out the core material n-docosane of the microcapsule with cracks and fine pore shells by absolute ethyl alcohol, floating the microcapsule with light specific gravity and the dissolved core material n-docosane on an upper layer of an alcohol-water solution after adding water, melting the dissolved core material n-docosane into oil at 70 ℃, and adhering the oil to oil absorption paper to form oil stains, thereby achieving the purpose of detecting the sealing performance of the microcapsule.
(1) A certain amount of a phase-change microcapsule sample taking polyurea resin prepared by a commercial interfacial polymerization method as a shell material and n-docosane as a core material is tested according to the method for testing the sealing performance of the microcapsule, and the phenomenon of oil stain on an oil absorption paper surface is observed. The microcapsule sample after ultrasonic oscillation for 15 minutes is tested according to the method for testing the sealing performance of the microcapsule, and the whole oil absorption paper surface is observed to be stained with oil stains in a star-shaped and dense manner. The samples of phase-change microcapsules in which a commercially available polyurea resin prepared by interfacial polymerization was used as a shell material and n-docosane was used as a core material were poor in sealing properties, and some of the microcapsule shell materials were damaged, such as cracks and pores.
(2) A certain amount of phase-change microcapsule sample (the embodiment 5 of the invention) taking organic silazane polymer resin prepared by the interfacial polymerization method as a shell material and n-docosane as a core material is tested according to the method for testing the sealing performance of the microcapsule, and no oil stain phenomenon on the oil absorption paper surface is observed. The microcapsule sample after being ultrasonically oscillated for 30 minutes was tested according to the method for testing the sealing property of the microcapsule, and it was observed that there was almost no oil stain on the oil-absorbing paper surface. The samples of the phase-change microcapsules in which the organic silazane polymer resin prepared by the interfacial polymerization method of the present patent is a shell material and n-docosane is a core material are excellent in sealing performance, and the shell material of the microcapsules hardly has damages such as cracks and pores.