KR20200018307A - Phase change energy storage microcapsule preparation and use thereof - Google Patents

Abstract

The present invention relates to a phase change energy storage microcapsule comprising: a wall material which is phenol/urea/aldehyde terpolymer; and a core material which is a phase change energy storage material, wherein the content of a nitrogen element in the wall material is less than or equal to 12 wt%, to a production method of a phase change microcapsule, and to application thereof.

Description

Manufacture and use of phase change energy storage microcapsules {PHASE CHANGE ENERGY STORAGE MICROCAPSULE PREPARATION AND USE THEREOF}

The present invention relates to a phase change energy storage microcapsule and a method and application thereof, and more particularly, to a microcapsule coated with a phase change energy storage material with a phenol / urea / aldehyde terpolymer and a method and application thereof. It is about.

Currently, the issue of using energy sources is becoming increasingly important. Phase change energy storage materials can be stored and released in large quantities through phase change at a constant temperature and reduce energy source waste, so they are widely used by scientists and widely applied. It is becoming. Phase change energy storage materials can be liquefied and flowed at high temperatures, and can be mixed in contact with other materials during use, thus affecting performance, thus packaging phase change energy storage materials using microcapsule techniques in practical applications. Should be.

Chinese patent application CN102191018A discloses the synthesis of low melting point paraffin microcapsules coated with resorcinol modified urea formaldehyde resin by one step method. In Chinese patent application CN104357019A, the thermal conductivity of urea-formaldehyde resin is added by adding a thermally conductive filler to the urea-formaldehyde resin wall material, coating paraffin by two-step method, and storing energy only through paraffin solid-solid phase change. Disclosed improvements. Chinese patent application CN104861935A discloses the preparation of microcapsules of solid-liquid phase change energy storage materials by two-step method. Chinese patent application CN105838334A discloses the preparation of resorcinol modified urea formaldehyde resin phase change energy storage microcapsules.

As can be seen from the published Chinese patent application, microcapsules coated with phase change energy storage materials with urea formaldehyde and its modified resins still have a number of problems. Mainly, 1. The latent heat retention rate is not ideal; 2. phase change energy storage materials are easily exuded; 3. Due to the large impact on the application system, severe thixotropy occurs in the system; 4. Since the surface of the wall material is rough, it appears that the system viscosity is significantly increased, resulting in a lower addition amount.

In view of the prior art, the inventors of the present invention have a wide range of fields in which the modified urea formaldehyde resin coats a phase change energy storage material to obtain a phase change energy storage microcapsule having a latent heat, a leak, and a low influence on an application system. The study was conducted. As a result, it was found that the above object can be achieved by copolymerizing with urea formaldehyde using phenol as the third monomer to reduce the content of the nitrogenous material of the wall material. The present invention has been completed based on the above findings.

It is an object of the present invention to provide microcapsules coated with a phase change energy storage material with a phenol / urea / aldehyde terpolymer.

Another object of the present invention is to provide a method of manufacturing the phase change energy storage microcapsules.

Yet another object of the present invention is to provide the phase change energy storage microcapsules for application in the field of adhesives.

According to an aspect of the present invention, in a phase change energy storage microcapsule comprising a wall material which is a phenol / urea / aldehyde terpolymer and a core material which is a phase change energy storage material, the content of nitrogen element in the wall material is 15% by weight. A phase change energy storage microcapsule is provided which is smaller or equal.

According to another aspect of the present invention, a step of emulsifying water, urea, phenol, an inorganic electrolyte salt, an emulsifier, and a phase change energy storage material under conditions of pH = 1.0 to 2.5; It further provides a method for producing a microcapsule coated with a phase change energy storage material with a phenol / urea / aldehyde terpolymer, comprising the step (2) of putting the aqueous solution of aldehyde at constant velocity into the emulsion of step (1).

According to another aspect of the invention, the phase change energy storage microcapsules of the invention provide applications in the field of adhesives.

The present invention manufactures a microcapsule coated with a phase change energy storage material with a phenol / urea / aldehyde terpolymer by carrying out acid control once using a one-step method and adding aldehydes at constant velocity. Raw materials are inexpensive and easy to obtain, the process is simple, insensitive to pH, the operating window is large, reproducible, and the production is easily extended.

The present invention has the following features.

1.The latent heat retention rate of microcapsules is about 85 ~ 95%, no excessively hot or too cold phenomenon.

2. The wall material is relatively thin, the content of wall material is small, and the heat shield effect is negligible.

3. The toughness of the wall material is good, not easily broken, and solve the problem of exudation of the core material of phenol-modified urea formaldehyde resin phase change energy storage microcapsules.

4. Compared to the conventional resorcinol modified urea formaldehyde resin phase change energy storage microcapsules, the method of the present invention disperses the microcapsules into single grains, has a smooth surface, the powder is smooth and does not clump, and is easy to apply in the application process. Dispersed, low amide bond content of the wall material (low nitrogen content), high steric hindrance, strong inertness, no interaction with other substances, small impact on the application system, no significant increase in viscosity.

5. Based on reaching higher performance, the cost is lower than other types of phase change energy storage microcapsules.

1 is a DSC cycle graph of 58 # semi-refined paraffin.
2 is a DSC cycle graph of 44 # paraffin.
3 is a DSC cycle graph of n-octadecane.
4 is a DSC cycle graph of a phase change energy storage microcapsules product according to Example 1. FIG.
5 is a DSC cycle graph of the phase change energy storage microcapsules product according to Example 2. FIG.
6 is a DSC cycle graph of a phase change energy storage microcapsules product according to Example 3. FIG.
7 is a DSC cycle graph of a phase change energy storage microcapsules product according to Example 10.
8 is a DSC cycle graph of the phase change energy storage microcapsules product according to Comparative Example 1. FIG.
9 is a DSC cycle graph of a phase change energy storage microcapsules product according to Comparative Example 2. FIG.
10 is a scanning electron micrograph of a phase change energy storage microcapsules product according to Comparative Example 1. FIG.
11 is a scanning electron micrograph of a phase change energy storage microcapsules product according to Comparative Example 2. FIG.
12 to 16 are optical micrographs at different time points in the cooling process of the phase change energy storage microcapsules product according to Example 10.
17 is a scanning electron micrograph of a phase change energy storage microcapsules product according to Example 10.

The phase change energy storage microcapsules of the present invention comprise a wall material and a core material, the wall material is a phenol / urea / aldehyde terpolymer, and the core material is a phase change energy storage material, wherein the nitrogen in the wall material The content of elements is less than or equal to 15% by weight. In the phase change energy storage microcapsules of the present invention, the surface of the wall material is smooth and free of prominent parts.

In the phase change energy storage microcapsules of the present invention, the wall material can be polymerized into urea, aldehyde and phenol, wherein the mass ratio of urea and phenol is less than or equal to 1:75 and preferably less than or equal to 1: 2. Wherein the mass ratio of phenol to aldehyde is from 3: 1 to 1: 3, preferably from 2: 1 to 1: 2, where the ratio range is any value between the endpoints, for example 2.5: 1,1 : 1.5. All of the phenols participate in the reaction of the entire urea / aldehyde, and the upper limit of its use should be such that the content of nitrogen in the wall material is less than or equal to 15%, preferably less than or equal to 8%, more preferably Should be ≤ 5%. The wall material may have a thickness of 200 to 500 nm, and preferably 350 to 400 nm. It should be explained that the thickness of the wall material can be any value between 200 and 500 nm, for example 260 nm, 320 nm, 330 nm, 345 nm, 380 nm, 420 nm, 480 nm and the like.

In the phase change energy storage microcapsules of the present invention, the mass ratio of the core material and the wall material may be 2 to 7.5: 1, preferably 4 to 7: 1. The core material is a phase change energy storage material, and the phase change energy storage material may be one or several of an inorganic phase change energy storage material or an organic phase change energy storage material. Phase change temperature <100 ° C, more preferably less than or equal to 85 ° C. The inorganic phase change energy storage material may be one or several of hydrous salts of calcium chloride, CaCl ₂ · 6H ₂ 0, BaS, CaHP0 ₄ , CaS0 ₄ , Ca (OH) ₂ , and alkaline earth metal acetates. The organic phase change energy storage material is n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eichoic acid, n-heneicoic acid, n Docoic acid, n-tricoic acid, n-tetracoic acid, capric acid, tetradecanoic acid, lauric acid, stearic acid, palmitic acid, hexadecanol, or one or several of 18 to 58 # paraffins. Where, the price of paraffin is inexpensive and stable in nature, is not too cold or precipitated, is not poisonous and does not corrode, is environmentally friendly, has about 18 to 30 carbon atoms, and the phase change temperature is in the range of 28 to 80 ℃ Phase change latent heat is in the range of 180-250 J / g and is extremely high in phase ratio energy storage material.

Compared with the conventional resorcinol modified urea formaldehyde resin, the microcapsules of the present invention are standard in shape, the surface of the wall material is smooth, there are no prominent protrusions, and the capsules are dispersed in single grains and accumulate significantly. It doesn't work. Since the ratio of phenol and urea was increased, the content of amide bonds (nitrogen element) in the wall material was reduced, and at the same time, the benzene ring was present in the wall material structure, so the hyperconjugation effect was that Since the benzene ring structure increases the space steric hindrance effect and does not generate a heat shielding effect, the phase change latent heat retention of the phase change energy storage capsule is greater than or equal to 85%, preferably 85 to 95%. .

The method of manufacturing the phase change energy storage microcapsules of the present invention realizes one acid control, reduces the process, the system reduces the sensitivity to pH, the operation window is large, the reproducibility is high, and the toughness of the wall material Improves glossiness. The manufacturing step of the phase change energy storage microcapsules is specifically as follows.

In step ①, emulsify water, urea, phenol, inorganic electrolyte salt, emulsifier and phase change energy storage material under the condition of pH = 1.0 to 2.5.

In step ②, an aqueous solution of aldehyde is placed at constant velocity into the emulsion of step ①.

The emulsification process of step ① may proceed by a method commonly used in the art, for example, a conventional emulsification method or a so-called reverse emulsification method may be used. In this step, the pH can be adjusted to 1.0 to 2.5 using a pH adjuster, can be adjusted before forming the emulsion in the system, it can also be adjusted after forming the emulsion.

In steps ① and ②, the mass ratio of urea and phenol may be less than or equal to 1: 1.75, preferably less than or equal to 1: 2; The mass ratio of phenol and aldehyde may be 3: 1 to 1: 3, preferably 2: 1 to 1: 2; The total amount of urea, phenol and aldehyde and the amount of phase change energy storage material should be such that the mass ratio of the core material and the wall material is 2 to 7.5: 1, preferably 4 to 7: 1; The amount of the inorganic electrolyte salt may be 1 to 5% of the total weight of urea, phenol and aldehyde, preferably 1.5 to 4%; The amount of emulsifier used may be 20 to 60% of the total weight of urea, phenol and aldehyde, preferably 25 to 50%, where each ratio range is any value between the two endpoints.

The inorganic electrolyte salt may be an inorganic material that is soluble in any water known to those skilled in the art and may be ionized to an anionic / positive ion, preferably one or several of ammonium salt, sodium salt and potassium salt; More preferably the ammonium salt is one or several of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium hypochlorite, ammonium sulfite, ammonium chlorate; More preferably the sodium salt is one or several of sodium sulfite, sodium chlorate, sodium chloride, sodium sulfate, sodium nitrate, sodium hypochlorite; More preferably, the potassium salt is one or several of potassium chloride, potassium sulfate, potassium nitrate, potassium hypochlorite, potassium sulfite and potassium chlorate.

The emulsifier may be one or several of polysaccharides, protein-based emulsifiers or water-soluble anionic emulsifiers, preferably using a mixture of a water-soluble anionic emulsifier and a polysaccharide or protein-based emulsifier; The polysaccharide or protein-based emulsifier is one or several of gum arabic, gelatin, guar gum, methyl cellulose; The water-soluble anionic emulsifier is preferably a carboxylate type anionic emulsifier or a sulfonate type anionic emulsifier, more preferably sodium oleate, sodium biate, sodium laurate, sodium naphthenate, sodium stearate, sodium dodecylbenzenesulfonate, sodium Sodium lauryl diphenyl ether disulfonate, sodium benzenesulfonate, sodium methylsulfonate, sodium dimethylbenzenesulfonate and sodium isopropylsulfonate.

The urea may be one or several of urea and a water-soluble substituted derivative thereof, preferably urea, methyl urea, ethyl urea, diethyl urea, hydroxyethyl urea, ethylene urea, dihydroxyethylene urea, n- Propylurea, isopropylurea, 1,3-dipropylurea, n-butylurea, isobutylurea, t-butylurea, phenylurea or mixtures thereof; The urea more preferably uses urea or hydroxyethyl urea. The aldehyde may be one or several of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, phenylacetaldehyde, phenylpropionaldehyde. The phenol may be a water soluble phenol, preferably resorcinol or phenol. The pH adjusting agent may be a strong proton donor or a mixture thereof, which is readily soluble in water, and more preferably one or several of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, hypochlorous acid. The amount of water used may comprise 30 to 80% of the total weight of the reaction system, preferably 40 to 70%.

In step ②, control is carried out within 1 to 4 hours, preferably within 2.5 to 3.5 hours, and an aqueous solution of aldehyde is placed at constant velocity in the emulsion of step ①. As the acid is introduced at constant velocity, the urea / aldehyde ratio in the reaction system decreases continuously over time. Linear element / aldehyde molecules dissolved in the continuous phase at the beginning of the reaction precipitate through semicrystallization under the influence of the reaction system, producing a dense and flexible inner wall material. In the middle and later stages of the reaction, the urea formaldehyde ratio changes continuously, so that the degree of crosslinking of the urea / aldehyde molecules is constantly increasing, the wall material gradually changes from semicrystalline precipitation to crosslinked polymerization precipitation, and the resulting wall material is internally The material is uniformly changed from the highly semi-crystalline dense flexible wall material to the high crosslinked rigid wall material, and has high flexibility in its entirety.The core material does not easily undergo stress concentration when the volume is changed, and is not easily fractured. The high density of the wall material prevents the core material from being easily exuded, thereby solving the problem of the core material of the single layer urea formaldehyde wall material phase change energy storage microcapsules being exuded. The concentration of the aqueous solution of the aldehyde is preferably 20 to 45% by weight, more preferably 25 to 45% by weight, preferably 30 to 40% by weight.

Steps ① and ② may be performed in a reactor having a heating function, for example, a three-necked flask having a heating cover, an electromagnetic heating stirring device, a reaction tank having a heating function, and the like, and the heating temperature is 30 to 30 °. The temperature is controlled at 95 ° C, preferably 45-85 ° C. In order to react the reaction more completely, after the completion of the dropwise addition of the aqueous solution of aldehyde, the reaction can be continued for 1 to 3 hours, the specific reaction time can be adjusted according to demand. The device for dropwise addition of an aqueous solution of aldehyde at constant speed may be a dropping funnel or a rectifying pump, preferably a rectifying pump.

More preferably, the method of the present invention is to reduce the reaction solution obtained in step ② to the environmental temperature and below, then take the slurry material of the upper layer, washed with water, dried and screened to obtain a phase change energy storage microcapsules ③ It may further include.

In step ③, in order to improve the yield, the reaction liquid is reduced to the environmental temperature and then left to stand for a predetermined time, and the settling time is determined according to the amount of the reactants used, and usually, it must be left for at least 2 hours; If the amount of reactants is large, the settling time should be extended appropriately; Longer settling times are better and can be adjusted according to actual production and yield requirements. In this step, the water washing should be performed at least twice, and then dried for at least 2 hours under the conditions of 50 to 60 ℃. Next, the number of water washes and the drying temperature and time can be adjusted according to the amount of reaction product. Screening is done using 60-100 mesh, preferably 70-80 mesh.

All raw materials used in the method of the present invention can be purchased commercially, and both industrial purity and analytical purity can be used.

In the present invention, "the surface of the wall material is smooth and there is no prominent part" means that there is not too much remarkable granular material on the outer surface of the wall material, and "the shape is standard" means It means that the shapes are basically similar. In the whole specification, unless otherwise stated, all percentages are by weight percentages, and the phase change process refers to the process of solid-liquid conversion of the phase change material in the phase change microcapsules.

The present invention is further described through the following specific examples, but the present invention is not limited thereto.

Example

Example 1

In a 250 ml flask, add 125 g deionized water, l.5 g urea, 3 g resorcinol, 1.8 g gum arabic, 0.3 g dodecylbenzenesulfonate, 0.3 g ammonium chloride, 38 Adjust pH = 1.2-1.3 with% hydrochloric acid and add 50 g of 58 # paraffin. It warms up to 65 degreeC, and emulsifies by stirring.

The temperature was maintained at 65 ° C., and 8.9 g of 37% aqueous formaldehyde solution was added at 0.1 ml / min using a rectifying pump, and the reaction was maintained for 2 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 2

In a 250 ml flask, add 100 g deionized water, 0.5 g urea, 2.5 g phenol, 1.8 g gum arabic, 0.3 g sodium dodecylbenzenesulfonate, 0.3 g ammonium chloride, and 38% hydrochloric acid. Adjust pH = 1.2-1.3 and add 40 g 44 # paraffin. It warms up to 55 degreeC, and emulsifies by stirring.

The temperature is maintained at 55 ° C., and 8.9 g of 37% aqueous formaldehyde solution is added at 0.1 ml / min using a rectifying pump, and the reaction is maintained for 2 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 3

In a 250 ml flask, add 125 g deionized water, 1.0 g urea, 2.5 g resorcinol, 2.3 g arabic rubber, 0.3 g dodecylbenzenesulfonate, 0.3 g ammonium chloride, Adjust pH = 1.2-1.4 with% sulfuric acid and add 50 g of n-octadecane. It warms up to 45 degreeC, and emulsifies by stirring.

The temperature was maintained at 45 ° C, 18.9 g of 37% aqueous formaldehyde solution was added at 0.1 ml / min using a rectifying pump, and the temperature was raised to 55 ° C to maintain the reaction for 2 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 4

In a 250 ml flask, add 125 g deionized water, l.5 g urea, 4.5 g resorcinol, 1.6 g gum arabic, 0.5 g sodium dodecylbenzenesulfonate, 0.4 g sodium chloride, 98% To pH = 1.4-1.5 and add 60 g of n-octadecane. It warms up to 45 degreeC, and emulsifies by stirring.

The temperature was maintained at 45 ° C, 7.5 g of 37% aqueous formaldehyde solution was added at 0.08 ml / min using a rectifying pump, and the temperature was raised to 55 ° C to maintain the reaction for 1.5 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 5

In a 250 ml flask, add 140 g deionized water, 0.5 g urea, 2 g resorcinol, 1.2 g gum arabic, 1.0 g sodium dodecylbenzenesulfonate, 0.35 g potassium chloride, 38% hydrochloric acid PH = 1.4-1.5 and add 45 g of n-octadecane. It warms up to 45 degreeC, and emulsifies by stirring.

The temperature was maintained at 45 ° C, 12.5 g of 37% aqueous formaldehyde solution was added at 0.12 ml / min using a rectifying pump, and the temperature was raised to 55 ° C to maintain the reaction for 2 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 6

In a 250 ml flask, add 120 g of deionized water, 1.0 g of urea, 3.0 g of resorcinol, 2.2 g of gum arabic, 0.5 g of sodium stearate, 0.35 g of potassium chloride, and 68% nitric acid. Adjust to 1.4-1.5, add 55 g of 58 # paraffin. It raises to 60 degreeC, and emulsifies by stirring.

The temperature is maintained at 60 ° C., and 12.5 g of 37% aqueous formaldehyde solution is added at 0.12 ml / min using a rectifying pump, and the reaction is maintained for 2 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 7

In a 250 ml flask, add 120 g deionized water, 1.0 g urea, 3.0 g resorcinol, 2.2 g gum arabic, 0.5 g sodium stearate, 0.35 g potassium chloride, pH 38 with hydrochloric acid = Adjust to 1.4-1.5, add 55 g of 58 # paraffin. It raises to 60 degreeC, and emulsifies by stirring.

The temperature is maintained at 60 ° C., and 12.5 g of 40% acetaldehyde aqueous solution is added at 0.12 ml / min using a rectifying pump, and the reaction is maintained for 2 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 8

In a 250 ml flask, add 120 g deionized water, 1.0 g hydroxyethyl urea, 3.0 g resorcinol, 2.2 g arabic rubber, 0.5 g sodium stearate, 0.35 g potassium chloride, 38% hydrochloric acid PH = 1.4-1.5 and add 55 g of 58 # paraffin. It raises to 60 degreeC, and emulsifies by stirring.

The temperature is maintained at 60 ° C., and 12.5 g of 40% acetaldehyde aqueous solution is added at 0.12 ml / min using a rectifying pump, and the reaction is maintained for 2 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 9

In a 250 ml flask, add 120 g of deionized water, 1.0 g of ethyl urea, 3.0 g of resorcinol, 2.2 g of gum arabic, 0.5 g of sodium stearate, 0.35 g of potassium chloride, and pH of 38% with hydrochloric acid. = 1.4-1.5 and add 55 g of 58 # paraffin. It raises to 60 degreeC, and emulsifies by stirring.

The temperature is maintained at 60 ° C., and 12.5 g of 40% acetaldehyde aqueous solution is added at 0.12 ml / min using a rectifying pump, and the reaction is maintained for 2 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Example 10: Extending the one-step method to prepare 58 # paraffin-coated microcapsules with resorcinol modified urea formaldehyde resin

100 K jacketed type reactor with high speed cutting homogenizer and bottom material outlet, 50 Kg deionized water, 0.6 Kg urea, 1.2 Kg resorcinol, 600 g Arabian rubber, 20 g dodecyl Add sodium benzenesulfonate, 120 g ammonium chloride, adjust pH = 1.2-1.3 with 38% hydrochloric acid, add 20 Kg of 58 # paraffin. The temperature is raised to 65 ° C., the paraffin is melted, and the high speed cutting homogenizer is operated to emulsify at l0000 rpm for 10 minutes.

The temperature was maintained at 60 ° C., and 3.56 Kg of 37% aqueous formaldehyde solution was added at 40 ml / min using a rectifying pump, and the reaction was maintained for 2 hours.

The reaction mother liquor was reduced to room temperature, allowed to stand for 6 hours, the lower suspension was discharged through the lower material outlet, the upper slurry phase was washed four times with deionized water, and dried at 50 ° C. for 5 hours. After screening with 80 mesh, a phase change energy storage microcapsule is obtained as a powder product.

Wet the microcapsules with water, prepare samples, and analyze and observe the phase change process of the product obtained with the optical microscope XSP-12CA (Shanghai First Optical Machinery Factory). The sample is first heated with an electric dryer, and after the phase change is complete (visually seeing no solid paraffin present), the heating is stopped and allowed to cool naturally, repeating this process three times, The process is recorded, a moving picture file is generated, and any one complete phase change process is captured and recorded at an interval of 30 seconds, and the results are shown in FIGS. 12 to 16.

Comparative Example 1: Prepare a microcapsule coated with 58 # paraffin with the resorcinol modified urea formaldehyde resin by conventional acid control one-step method

In a 250 ml flask, add 90 g deionized water, 4.4 g urea, 0.44 g resorcinol, 35 g 5% aqueous polyvinyl alcohol, 0.3 g sodium dodecylbenzenesulfonate, 0.5 g sodium chloride Adjust pH = 1.2-1.5 with 38% hydrochloric acid, add 50 g of 58 # paraffin. The temperature is raised to 65 ° C. and the paraffin is dissolved and emulsified for 10 minutes.

The temperature was maintained at 65 ° C., 8.9 g of 37% aqueous formaldehyde solution was added, adjusted to pH = 5.0 with 38% hydrochloric acid, maintained for 0.5 hour, adjusted to pH = 4.2 with 38% hydrochloric acid, Maintained for 0.5 hour, adjusted to pH = 3.8 with 38% hydrochloric acid, maintained for 0.5 hour, adjusted to pH = 3.5 with 38% hydrochloric acid, maintained for 0.5 hour, pH = 3.2 with 38% hydrochloric acid The temperature was decreased to 0.02 per minute, slowly decreased to 2.0, the reaction was maintained for 1 hour, and the temperature was raised to 72 ° C and maintained for 0.5 hours.

The reaction mother liquor was reduced to room temperature, left for 2 hours, the lower layer suspension was removed, the upper slurry phase material was washed twice with deionized water, dried at 50 ° C. for 2 hours and screened with 80 mesh. Thus, a phase change energy storage microcapsules that are powder products are obtained.

Comparative Example 2

The steps of Example 1 are duplicated, but the difference is to use 0.5 g of resorcinol.

Phase change of the microcapsules prepared in Examples and Comparative Examples was analyzed by differential scanning calorimetry, and specific test conditions were performed once using a DSC instrument (TA Instruments-Waters.LLT) of model TAQ200. The temperature rising process is the start temperature is 0 ℃, the end temperature is 100 ℃, 120 ℃, 150 ℃ and the speed is 20 ℃ / min, the temperature reduction process is the start temperature is 100 ℃, 120 ℃, 150 ℃ and the end temperature Is 0 ° C. and the speed is 20 ° C./min. The thickness of the wall material is measured by magnifying 200 times with a microscope XSP-12CA (Shanghai First Optical Machinery Factory). 10 g of the microcapsules prepared in Examples and Comparative Examples were placed in a silicone oil having a viscosity of 300 g of 300 g, uniformly mixed with a speedmixer, and the viscosity of the microcapsules was measured with a rotor viscometer, and the model was 10. The thixotropy is measured using a rotor having a fold difference. For example, the ratio of the viscosity measured by the 50 # rotor and the viscosity measured by the 5 # rotor is the thixotropy index. 50 g of sample is taken and placed in a 100 L inlet-opened vessel, stirred with a glass rod to lift some samples about 20 cm away from the inlet of the container, allowing the sample to flow automatically into the vessel from the glass rod, Observe whether the sample is leveling itself quickly, and determine whether the sample is oily. Take a small amount of sample, place it on the speculum plate, make a sample piece, and repeatedly heat the sample piece with a heat gun to circulate the microcapsule in phase change, and at the same time, break the microcapsule in the process under the optical microscope or Observe the exudation situation. The content of nitrogen element was measured with an SEM scanning electron microscope combined energy spectrometer (Tsinghua University Analysis Center, probe distance l5 mm, voltage 15 KV), and the surface roughness and the size of the capsule were observed. The results are shown in the table below.

Sample Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Latent heat J / g 149.7 196.4 202.5 212.4 207.1 205.4 202.3 201.1 202.9 201.1 201.7 197.4 % Retention 68 89.2 92 89.2 90.2 89.4 89.4 91.4 92.2 91.4 91.7 89.7 Viscosity Cps 33000 6700 4200 4000 4100 4200 4300 4200 4400 4200 4300 4200 Thixotropic index 8 5 2.8 1.5 2.3 2 2.5 2.9 2.5 2.5 2.7 3 Can flow impossible impossible possible possible possible possible possible possible possible possible possible possible Microcapsule shape Surface is rough, accumulated and coalesced Slightly rough, scattered into single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Smooth surface, dispersed in single grains Effusion stringency usually none none none none none none none none none none Wall thickness / nm - 450 350 370 360 350 400 390 367 480 450 400 Nitrogen content /% 30.2 20.5 10.1 3.4 5.5 4.9 6.7 7.2 6.8 6.7 7.7 10.7

Comparative Example 1 uses a conventional one-step method, controls the reaction rate by adjusting the pH value, high demand for acid adjustment process, narrow operating window, difficult to control in the expansion process. pH = 3.5 to 2.8 is a critical range, so overly fast adjustments can result in coarse, coalescing or agglomeration of the microcapsule surface, and too late for insufficient reaction rates. The formed wall material is highly fragile and easily broken under stress. Comparative Example 2 uses essentially the same conditions as in Example 1, but reduces the amount of resorcinol used, and consequently significantly increases the viscosity in the silicone oil.

Example 1 is a preferred condition to increase the phenol and urea ratio and improve the shape of the microcapsules. The fluidity was good as a result of detecting the sample with silicone oil.

Example 10 is an extended intermediate test of the preferred conditions of Example 1, and the method of the present invention is consistent with a test with a simple process, large operating window and small product mass in the expansion process.

The heat dissipation graph of the DSC shows that the phase change latent heat retention of the phase change energy storage microcapsules prepared by adding aldehyde at constant speed is more than 85% and the latent heat retention of the conventional method is 68%. .

The above is a preferred embodiment of the present invention, and not limiting the present invention, those skilled in the art can make various changes and modifications to the present invention. Any modifications, equivalent substitutions, improvements, etc., which are made under the premise without departing from the spirit and principles of the present invention, should all fall within the protection scope of the present invention.

Claims (18)

A phase change energy storage microcapsule comprising a wall material which is a phenol / urea / aldehyde terpolymer and a core material which is a phase change energy storage material,
Phase change energy storage microcapsule, characterized in that the content of the nitrogen element in the wall material is less than or equal to 15% by weight.
The method of claim 1,
The thickness of the wall material is 200 ~ 500 nm, phase change energy storage microcapsule, characterized in that 350 ~ 400 nm.
The method according to claim 1 or 2,
Phase change energy storage microcapsule, characterized in that the content of the nitrogen element in the wall material is less than or equal to 8% by weight, preferably less than or equal to 5% by weight.
The method according to any one of claims 1 to 3,
The mass ratio of the core material and the wall material is 2 to 7.5: 1, preferably 4 to 7: 1 phase change energy storage microcapsule.
The method according to any one of claims 1 to 4,
The phase change energy storage material may be one or several of an inorganic phase change energy storage material or an organic phase change energy storage material, and preferably, the phase change temperature of the phase change energy storage material is <100 ° C. Energy storage microcapsules.
The method of claim 5,
The inorganic phase change energy storage material may be one or several of hydrous salts of calcium chloride, CaCl ₂ · 6H ₂ 0, BaS, CaHP0 ₄ , CaS0 ₄ , Ca (OH) ₂ , alkaline earth metal acetates,
The organic phase change energy storage material is n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eichoic acid, n-heneicoic acid, n Docoic acid, n-tricoic acid, n-tetracoic acid, capric acid, tetradecanoic acid, lauric acid, stearic acid, palmitic acid, hexadecanol, or one or several of 18 to 58 # paraffins. Phase change energy storage microcapsules characterized in that there is.
The method according to any one of claims 1 to 6,
And said wall material has a smooth outer surface.
The method according to any one of claims 1 to 7,
And the wall material has a smooth outer surface and has a latent heat retention of the microcapsules ≥ 85%.
The method according to any one of claims 1 to 8,
The microcapsule is a phase change energy storage microcapsule, characterized in that to allow the application system to flow.
The method according to any one of claims 1 to 9,
The microcapsule is a phase change energy storage microcapsule, characterized in that does not leak in the process of repeating the phase change circulation.
A method for producing a phase change energy storage microcapsule according to any one of claims 1 to 10,
emulsifying the water, urea, phenol, inorganic electrolyte salt, emulsifier, and phase change energy storage material at a condition of pH = 1.0 to 2.5;
Method of producing a phase change energy storage microcapsule comprising the step (2) of putting the aqueous solution of aldehyde at a constant velocity into the emulsion of step (1).
The method of claim 11,
The step ① and step ② is a method of manufacturing a phase change energy storage microcapsule, characterized in that proceeds under the conditions of 45 ~ 85 ℃.
The method of claim 12,
The step ② is a method of producing a phase change energy storage microcapsule, characterized in that the reaction for 1 to 3 hours after the addition of an aqueous solution of aldehyde.
The method according to any one of claims 11 to 13,
Reducing the reaction solution obtained in step ② to the environmental temperature and below, and further comprising the step (3) of taking the slurry material of the upper layer, washing with water, drying and screening ③. .
The method according to any one of claims 11 to 14,
Method of producing a phase change energy storage microcapsule, characterized in that to control the pH of the step ① to 1.0 ~ 2.5 using a pH adjuster.
The method according to any one of claims 11 to 15,
The mass ratio of said urea and phenol is less than or equal to 1: 1.75, preferably less than or equal to 1: 2; The mass ratio of the phenol and the aldehyde is 3: 1 to 1: 3; The total amount of urea, phenol and aldehyde and the amount of phase change energy storage material used should be such that the mass ratio of the core material and the wall material is between 2 and 7.5: 1, preferably between 4 and 7: 1;
The amount of the inorganic electrolyte salt is 1 to 5% of the total weight of urea, phenol and aldehyde, preferably 1.5 to 4%;
The amount of the emulsifier used is 20 to 60%, preferably 25 to 50% of the total weight of urea, phenol and aldehyde;
The inorganic electrolyte salt may be one or several of ammonium salt, sodium salt and potassium salt;
The emulsifier may be one or several of polysaccharides, protein-based emulsifiers or water-soluble anionic emulsifiers;
The urea may be one or several of urea and a water soluble substituted derivative thereof;
The aldehyde may be one or several of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, phenylacetaldehyde, phenylpropionaldehyde;
The phenol is a water-soluble phenol, preferably resorcinol or phenol;
Wherein said pH regulator is a strong proton donor that is readily soluble in water.
The method of claim 16,
The ammonium salt may be one or several of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium hypochlorite, ammonium sulfite, ammonium chlorate;
The sodium salt may be one or several of sodium sulfite, sodium chlorate, sodium chloride, sodium sulfate, sodium nitrate, sodium hypochlorite;
The potassium salt may be one or several of potassium chloride, potassium sulfate, potassium nitrate, potassium hypochlorite, potassium sulfite, potassium chlorate;
The polysaccharide or protein-based emulsifier may be one or several of gum arabic, gelatin, guar gum, methyl cellulose;
The water-soluble anionic emulsifier may be a carboxylate type anionic emulsifier or a sulfonate type anionic emulsifier;
The strong proton donor easily soluble in water may be one or several of hydrochloric acid, sulfuric acid, nitric acid, acetic acid and hypochlorous acid.
Application of the phase change energy storage microcapsules according to claim 1 in the field of adhesives.

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