Multifunctional composite energy-saving material for building envelope and preparation method of multifunctional composite energy-saving material

Abstract

The invention relates to the technical field of building energy-saving materials, in particular to a building envelope structure multifunctional composite energy-saving material and a preparation method thereof.The building envelope structure multifunctional composite energy-saving material is prepared from, by weight, 90-110 parts of lightweight aggregate, 15-30 parts of cement-based binder and 15-30 parts of microcapsule phase change unit; the particle size of the microcapsule phase change unit is 50-200 [mu] m, the microcapsule phase change unit is composed of a core-shell structure, the core of the microcapsule phase change unit is an organic phase change substance with the phase change temperature of 20-30 DEG C, and the shell of the microcapsule phase change unit is a cross-linked polymer layer doped with modified nano ferroferric oxide. The system effectively stabilizes indoor temperature fluctuation, reduces air conditioner energy consumption, can be widely applied to outer walls, inner walls, roofs, floors and other parts of buildings, and provides an efficient and energy-saving solution for modern buildings.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of building materials and energy-saving technology, and particularly relates to a multifunctional composite energy-saving material for building envelope structure and a preparation method thereof. BACKGROUND

[0002] With the increasing demand for building energy saving, the application of multifunctional composite energy-saving materials in building envelope structure has gradually become a research hotspot. Such materials not only need to have excellent thermal insulation performance, but also need to consider phase change temperature regulation, sound insulation and noise reduction, environmental protection, construction convenience and long-term durability, etc., to meet the requirements of modern buildings for efficient energy saving and intelligent development. However, the existing building materials still have obvious deficiencies in realizing multifunctional composite performance. The patent with publication number CN104773985B proposes a light composite building energy-saving thermal insulation material composed of Portland cement 42.5R, fibrous water magnesium, magnesium silicate long fur, wood fiber, light magnesium oxide, polypropylene fiber and other raw materials, which has the characteristics of thermal insulation and energy saving, fireproof and non-combustible, environmental protection and waterproof, and is suitable for thermal insulation of building outer walls, inner walls, roofs and other parts. However, the technical solution mainly focuses on the improvement of thermal insulation performance, does not involve phase change temperature regulation function, and cannot utilize the characteristics of phase change materials to absorb or release a large amount of latent heat at the phase change temperature point to smooth the indoor temperature fluctuation, thereby improving the thermal comfort and reducing the air conditioning energy consumption. In addition, the material adopts mechanical spraying construction method, which is convenient for construction, but has high requirements for base treatment, and the durability and stability after long-term use need to be further verified. The patent with publication number CN107002404B proposes a building material installed between the floor partition layer and the bottom layer, which can effectively block or inhibit the noise transmission between the floors of the building through the design optimization of the supporting member and the multiple damping members. However, the technical solution mainly focuses on the optimization of sound insulation performance, lacks comprehensive consideration of energy-saving performance, and fails to integrate phase change temperature regulation or other multifunctional composite characteristics. At the same time, the structural design is relatively complex, the installation is difficult, and the influence on the overall load of the building needs to be further evaluated. In addition, the single function of the material limits its wide application in modern building envelope structure.

[0003] The above problems show that the existing building materials still have significant deficiencies in realizing multifunctional composite performance. SUMMARY

[0004] In order to solve the above problems, the application proposes a multifunctional composite energy-saving material for building envelope structure and a preparation method thereof, which effectively smooths the indoor temperature fluctuation, reduces the air conditioning energy consumption, and can be widely applied to building outer walls, inner walls, roofs and floors, etc., to provide an efficient energy-saving solution for modern buildings.

[0005] To achieve the above purpose, the technical solution of the application is:

[0006] A multifunctional composite energy-saving material for building envelope, comprising, by weight, 90-110 parts of lightweight aggregate, 15-30 parts of cement-based binder, and 15-30 parts of microcapsule phase change unit.

[0007] The microcapsule phase change unit has a particle size of 50-200 μm and is composed of a core-shell structure, wherein the core is an organic phase change substance with a phase change temperature of 20-30 ℃, and the shell is a cross-linked polymer layer doped with modified nano-Fe3O4.

[0008] The energy-saving mechanism of the multifunctional composite energy-saving material for building envelope of the present application is based on the synergistic effect of lightweight aggregate and microcapsule phase change unit. The lightweight aggregate forms a low thermal conductivity layer through its porous structure, passively hinders the conduction of external heat to the indoor (in summer) or the indoor heat to the outside (in winter), and provides basic thermal insulation. The core of the microcapsule phase change unit, an organic phase change substance with a phase change temperature of 20-30 ℃ (the comfortable temperature range for human body), actively undergoes phase change (absorbs heat during melting / releases heat during solidification) when the ambient temperature changes, dynamically absorbs or releases a large amount of heat using the latent heat of phase change, thereby effectively buffering the indoor temperature fluctuations (absorbing heat to suppress temperature rise during high temperature period, releasing heat to delay temperature drop during low temperature period), and significantly reducing the peak load and energy consumption of air conditioning and heating systems. The cross-linked polymer shell of the microcapsule ensures that the phase change substance does not leak during repeated phase change cycles, is compatible with the matrix, and maintains structural stability. The combination of the two provides the building envelope with excellent dynamic thermal inertia and temperature self-adaptive regulation capability, achieving intelligent regulation and control of the building thermal environment and year-round energy saving.

[0009] Preferably, the organic phase change substance is one or more of paraffin, fatty acid or alcohol compound.

[0010] Preferably, the cross-linked polymer layer is formed by in-situ polymerization reaction of silane-modified nano-Fe3O4 compounded pre-polymer monomer or styrene and divinylbenzene or triethyl citrate.

[0011] Preferably, the lightweight aggregate is one or more of expanded perlite, ceramsite or foamed glass.

[0012] Preferably, the cement-based binder is Portland cement or sulphoaluminate cement.

[0013] The present application also discloses a preparation method of the above multifunctional composite energy-saving material for building envelope, comprising the following steps:

[0014] by weight:

[0015] Step (1): Heat 100 parts of organic phase change substance to a molten state, add 2-4 parts of emulsifier for high-speed shearing emulsification treatment to obtain an emulsion with a particle size of 50-200 μm;

[0016] Step (2): adding 100-120 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 3-5 parts of a cross-linking agent to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit;

[0017] The preparation process of the prepolymer monomer compounded with silane-modified nano-ferroferric oxide is as follows:

[0018] Step (2.1): dispersing 100 parts of nano-ferroferric oxide in 180-220 parts of an ethanol-water mixture with a volume ratio of 2-3:1, adding 15-17 parts of a silane coupling agent KH550, and ultrasonically treating at 60° C. for 30 minutes to obtain a silanized nano-ferroferric oxide dispersion;

[0019] Step (2.2): reacting 100-140 parts of melamine with 300 parts of a 37% formaldehyde solution (molar ratio 1:2.8) at pH 8-9 (adjusted with aqueous ammonia) and 70-90° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0020] Step (2.3): adding the dispersion obtained in step (2.1) to the prepolymer in step (2.2), stirring at a constant temperature of 60-70° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide;

[0021] Step (3): 90-110 parts of lightweight aggregate, 15-30 parts of cement-based binder and 15-30 parts of microcapsule phase change unit are mixed evenly, and appropriate amount of water is added to stir to form a slurry;

[0022] Step (4): pouring the slurry obtained in step (3) into a mold, vibrating and compacting it, and then curing it, and demoulding it to obtain a composite energy-saving material.

[0023] By selecting an alkali-resistant, robust cross-linked polymer as the shell and optimizing its particle size and surface properties, the microencapsulated phase change units can be successfully compounded with cement-based binders to form a stable and durable structure. This excellent compatibility enables the phase change function to function stably and long-term within the cement matrix, providing the foundation for the composite material's high performance and energy conservation.

[0024] The molten organic phase change material is sheared at high speed under the action of an emulsifier, using mechanical energy to overcome the phase change material's inherent aggregation tendency and interfacial tension between the two phases. The emulsifier molecules are directionally adsorbed at the oil-water interface, forming a stable interfacial film, reducing interfacial energy and generating steric hindrance / electrostatic repulsion, thereby inhibiting droplet coalescence and achieving uniform dispersion of the phase change material in the aqueous phase at the target particle size, forming a kinetically stable emulsion. A water-soluble prepolymer monomer and a crosslinker are added to the emulsion, where the prepolymer accumulates on the surface of the phase change droplets and undergoes interfacial polymerization. During the reaction, the monomers gradually polymerize at the droplet interface to form linear polymer chains. The crosslinker then initiates interchain crosslinking reactions, forming a three-dimensional network structure. This network structure continues to grow and solidify on the droplet surface, ultimately forming a dense and mechanically strong crosslinked polymer shell that completely encapsulates the phase change core within the microcapsule, achieving both physical isolation and chemical protection for the solid-liquid phase change material. Lightweight aggregate forms the main skeleton, providing the foundation for the pore structure. Cement particles fill the interstices between the aggregates and encapsulate the microcapsules, initially wetting all particles through surface adsorption. The addition of water triggers surface wetting and initial hydration reactions of the cement particles, forming a viscous cement paste. Viscous and capillary forces create a continuous transition phase between the particles, adhering the components and temporarily stabilizing their dispersion, resulting in a plastic, homogeneous composite slurry system. After the slurry is vibrated and compacted in a mold, the water further optimizes particle arrangement (reducing porosity) and triggers a deep hydration reaction in the cement: cement minerals dissolve to form calcium ions and silicate ions, which react to form calcium silicate hydrate (CSH) gel and calcium hydroxide (CH) crystals. The CSH gel, a nanoscale cementitious material, tightly bonds to the aggregate and microcapsule surfaces, forming a three-dimensional network-like bonding phase. The pores of the lightweight aggregate and the microcapsule shell serve as a rigid support phase during the curing process, synergizing with the cement gel to form an integrated composite structure, imparting the material's ultimate mechanical strength and permanently anchoring the functional units (phase change capsules).

[0025] In this scheme, nano-ferroferric oxide is modified with the silane coupling agent KH550 and then bonded to melamine-formaldehyde resin to form Fe-O-Si covalent bonds, constructing a percolation heat-conducting network and significantly accelerating the heat storage / release response speed of the phase change material. At the same time, the mechanical strength and impermeability of the microcapsule shell are enhanced, and the magnetic heat absorption-uniform heat transfer characteristics are used to reduce the temperature fluctuation of the building envelope and comprehensively improve energy-saving efficiency.

[0026] Preferably, in step (1), the emulsifier is a nonionic surfactant, and the emulsification time is 10-30 minutes.

[0027] Preferably, in step (2), the cross-linking agent is triethyl citrate.

[0028] Preferably, in step (4), the curing conditions are a temperature of 20-30° C., a humidity of 80% to 95%, and a curing time of 7-14 days.

[0029] Preferably, in step (1), the organic phase change material is one or more of paraffin, fatty acid or alcohol compounds.

[0030] Preferably, the lightweight aggregate is one or more of expanded perlite, ceramsite or foam glass.

[0031] Preferably, the cement-based binder is silicate cement or sulphoaluminate cement.

[0032] Compared with existing technologies, the advantages of this solution are:

[0033] This solution replaces traditional directly doped phase change materials with core-shell structured microcapsule phase change units. The cross-linked polymer layer of the outer shell effectively isolates the organic phase change material from contact with the alkaline cement matrix, fundamentally addressing the leakage, migration, and chemical corrosion issues of the phase change components. Furthermore, the lightweight aggregate, cement matrix, and capsule phase change units are synergistically compounded at a gradient scale (aggregate macropores / cement microfilling / capsule functional regulation) to avoid inorganic-organic hybrid interface failure and achieve independent optimization and integrated integration of thermal insulation and heat storage functions.

[0034] 2. In-situ polymerization at the emulsion interface directly constructs a cross-linked polymer shell on the surface of the phase change droplet in one step, simplifying the complex process of traditional microcapsule separation and drying, and avoiding capsule damage; lightweight aggregate, cement dry powder and solid microcapsules are first mixed, and then water is added and stirred to minimize the risk of swelling / scouring of the capsule shell by the high water content slurry, ensuring the integrity and uniformity of the functional units, and strong process controllability. DETAILED DESCRIPTION

[0035] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0036] Example 1

[0037] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0038] By weight:

[0039] Step (1): 100 parts of an organic phase change material are heated to a molten state, 3 parts of an emulsifier (polyoxyethylene fatty acid ester) are added, and high-speed shear emulsification treatment is performed for 15 minutes to obtain an emulsion with a particle size of 80-100 μm;

[0040] Step (2): adding 100 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 4 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit;

[0041] Step (2.1): Disperse 100 parts of nano-ferroferric oxide (particle size 20 nm) in 200 parts of a 3:1 ethanol-water mixture by volume, add 15 parts of a silane coupling agent KH550, and ultrasonically treat at 60°C for 30 minutes at a power of 300 W to obtain a silanized nano-ferroferric oxide dispersion;

[0042] Step (2.2): reacting 120 parts of melamine with 300 parts of a 37% formaldehyde solution at pH 8.5 and 75° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0043] Step (2.3): adding the dispersion obtained in step (2.1) to the melamine-formaldehyde prepolymer obtained in step (2.2), and stirring at a constant temperature of 65° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide;

[0044] Step (3): 90 parts of expanded perlite, 25 parts of Portland cement and 25 parts of microcapsule phase change units are mixed evenly, and appropriate amount of water is added to stir to form a slurry;

[0045] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 25° C. and a humidity of 85% for 10 days. After demoulding, the composite energy-saving material is obtained.

[0046] Example 2

[0047] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0048] By weight:

[0049] Step (1): 100 parts of paraffin wax were heated to a molten state, 3 parts of emulsifier (polyoxyethylene fatty acid ester) were added, and high-speed shear emulsification treatment was performed for 20 minutes to obtain an emulsion with a particle size of 80-120 μm;

[0050] Step (2): adding 100 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 4 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit;

[0051] Step (2.1): 100 parts of nano-ferroferric oxide (particle size 20 nm) were dispersed in 180 parts of a 3:1 ethanol-water mixture, 15 parts of a silane coupling agent KH550 were added, and the mixture was ultrasonically treated at 60°C for 30 minutes at a power of 300 W to obtain a silanized nano-ferroferric oxide dispersion;

[0052] Step (2.2): reacting 130 parts of melamine with 300 parts of a 37% formaldehyde solution at pH 8.5 and 75° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0053] Step (2.3): adding the dispersion obtained in step (2.1) to the melamine-formaldehyde prepolymer obtained in step (2.2), and stirring at a constant temperature of 65° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide;

[0054] Step (3): 95 parts of expanded perlite, 20 parts of Portland cement and 25 parts of microcapsule phase change units are mixed evenly, and an appropriate amount of water is added to stir to form a slurry;

[0055] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 22° C. and a humidity of 90% for 12 days. After demoulding, a composite energy-saving material is obtained.

[0056] Example 3

[0057] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0058] By weight:

[0059] Step (1): 100 parts of paraffin wax were heated to a molten state, 4 parts of an emulsifier (polyoxyethylene fatty acid ester) were added, and high-speed shear emulsification treatment was performed for 25 minutes to obtain an emulsion with a particle size of 120-150 μm;

[0060] Step (2): adding 110 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 4 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit;

[0061] Step (2.1): Disperse 100 parts of nano-ferroferric oxide (particle size 20 nm) in 200 parts of a 3:1 ethanol-water mixture by volume, add 15 parts of a silane coupling agent KH550, and ultrasonically treat at 60°C for 30 minutes at a power of 300 W to obtain a silanized nano-ferroferric oxide dispersion;

[0062] Step (2.2): reacting 120 parts of melamine with 300 parts of a 37% formaldehyde solution at pH 8.5 and 75° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0063] Step (2.3): adding the dispersion obtained in step (2.1) to the melamine-formaldehyde prepolymer obtained in step (2.2), and stirring at a constant temperature of 65° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide;

[0064] Step (3): 100 parts of expanded perlite, 25 parts of Portland cement and 20 parts of microcapsule phase change units are mixed evenly, and an appropriate amount of water is added and stirred into a slurry;

[0065] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 28° C. and a humidity of 82% for 14 days. After demoulding, a composite energy-saving material is obtained.

[0066] Example 4

[0067] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0068] By weight:

[0069] Step (1): 100 parts of paraffin wax were heated to a molten state, 2 parts of emulsifier (polyoxyethylene fatty acid ester) were added, and high-speed shear emulsification treatment was performed for 10 minutes to obtain an emulsion with a particle size of 150-180 μm;

[0070] Step (2): adding 100 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 5 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit;

[0071] Step (2.1): Disperse 100 parts of nano-ferroferric oxide (particle size 20 nm) in 200 parts of a 3:1 ethanol-water mixture by volume, add 15 parts of a silane coupling agent KH550, and ultrasonically treat at 60°C for 30 minutes at a power of 300 W to obtain a silanized nano-ferroferric oxide dispersion;

[0072] Step (2.2): reacting 120 parts of melamine with 300 parts of a 37% formaldehyde solution at pH 8.5 and 75° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0073] Step (2.3): adding the dispersion obtained in step (2.1) to the melamine-formaldehyde prepolymer obtained in step (2.2), and stirring at a constant temperature of 65° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide;

[0074] Step (3): 105 parts of expanded perlite, 18 parts of Portland cement and 26 parts of microcapsule phase change units are mixed evenly, and an appropriate amount of water is added to stir to form a slurry;

[0075] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 30° C. and a humidity of 95% for 7 days. After demoulding, a composite energy-saving material is obtained.

[0076] Example 5

[0077] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0078] By weight:

[0079] Step (1): 100 parts of paraffin wax were heated to a molten state, 3 parts of emulsifier (polyoxyethylene fatty acid ester) were added and high-speed shear emulsification was performed for 30 minutes to obtain an emulsion with a particle size of 180-200 μm;

[0080] Step (2): adding 100 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 4 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit;

[0081] Step (2.1): Disperse 100 parts of nano-ferroferric oxide (particle size 20 nm) in 200 parts of a 3:1 ethanol-water mixture by volume, add 15 parts of a silane coupling agent KH550, and ultrasonically treat at 60°C for 30 minutes at a power of 300 W to obtain a silanized nano-ferroferric oxide dispersion;

[0082] Step (2.2): reacting 120 parts of melamine with 300 parts of a 37% formaldehyde solution at pH 8.5 and 75° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0083] Step (2.3): adding the dispersion obtained in step (2.1) to the melamine-formaldehyde prepolymer obtained in step (2.2), and stirring at a constant temperature of 65° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide;

[0084] Step (3): 110 parts of expanded perlite, 22 parts of Portland cement and 28 parts of microcapsule phase change units are mixed evenly, and an appropriate amount of water is added to stir to form a slurry;

[0085] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 20° C. and a humidity of 88% for 9 days. After demoulding, a composite energy-saving material is obtained.

[0086] Comparative Example 1

[0087] The difference from Example 1 is that no microcapsule phase change unit is added:

[0088] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0089] By weight:

[0090] 90 parts of expanded perlite and 25 parts of Portland cement were evenly mixed, and an appropriate amount of water was added to stir into a slurry; the slurry was poured into a mold, vibrated to compact it, and then cured at a temperature of 25° C. and a humidity of 85% for 10 days. After demolding, a composite energy-saving material was obtained.

[0091] Comparative Example 2

[0092] The difference from Example 1 is that silane-modified nano-ferroferric oxide is not added:

[0093] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0094] By weight:

[0095] Step (1): 100 parts of an organic phase change material are heated to a molten state, 3 parts of an emulsifier (polyoxyethylene fatty acid ester) are added, and high-speed shear emulsification treatment is performed for 15 minutes to obtain an emulsion with a particle size of 80-100 μm;

[0096] Step (2): adding 100 parts of prepolymer monomer and 4 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain microcapsule phase change units;

[0097] Step (3): 90 parts of expanded perlite, 25 parts of Portland cement and 25 parts of microcapsule phase change units are mixed evenly, and appropriate amount of water is added to stir to form a slurry;

[0098] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 25° C. and a humidity of 85% for 10 days. After demoulding, the composite energy-saving material is obtained.

[0099] Comparative Example 3

[0100] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0101] By weight:

[0102] The difference from Example 1 is that the modified nano-ferroferric oxide is added in excess:

[0103] Step (1): 100 parts of an organic phase change material are heated to a molten state, 3 parts of an emulsifier (polyoxyethylene fatty acid ester) are added, and high-speed shear emulsification treatment is performed for 15 minutes to obtain an emulsion with a particle size of 80-100 μm;

[0104] Step (2): adding 100 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 4 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit;

[0105] Step (2.1): 150 parts of nano-ferroferric oxide (particle size 20 nm) were dispersed in 200 parts of a 3:1 ethanol-water mixture, 15 parts of a silane coupling agent KH550 were added, and the mixture was ultrasonically treated at 60°C for 30 minutes at a power of 300 W to obtain a silanized nano-ferroferric oxide dispersion.

[0106] Step (2.2): reacting 120 parts of melamine with 300 parts of a 37% formaldehyde solution at pH 8.5 and 75° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0107] Step (2.3): adding the dispersion obtained in step (2.1) to the melamine-formaldehyde prepolymer obtained in step (2.2), and stirring at a constant temperature of 65° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide;

[0108] Step (3): 90 parts of expanded perlite, 25 parts of Portland cement and 25 parts of microcapsule phase change units are mixed evenly, and appropriate amount of water is added to stir to form a slurry;

[0109] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 25° C. and a humidity of 85% for 10 days. After demoulding, the composite energy-saving material is obtained.

[0110] Comparative Example 4

[0111] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0112] By weight:

[0113] Step (1): 100 parts of an organic phase change material are heated to a molten state, 3 parts of an emulsifier (polyoxyethylene fatty acid ester) are added, and high-speed shear emulsification treatment is performed for 15 minutes to obtain an emulsion with a particle size of 80-100 μm;

[0114] Step (2): adding 100 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 4 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit;

[0115] Step (2.1): 100 parts of nano-magnetic iron oxide (particle size 20 nm) was dispersed in 200 parts of a mixture of ethanol-water with a volume ratio of 3:1, 15 parts of silane coupling agent KH550 was added, and ultrasonic treatment was carried out at 60°C for 30 min, power 300W, to obtain a silanized modified nano-magnetic iron oxide dispersion;

[0116] Step (2.2): 120 parts of melamine was reacted with 300 parts of 37% formaldehyde solution at pH = 8.5, 75°C for 40 min to form melamine-formaldehyde prepolymer;

[0117] Step (2.3): The dispersion obtained in step (2.1) was added to the melamine-formaldehyde prepolymer obtained in step (2.2), and constant temperature stirring was carried out at 65°C for 90 min to form a silane-modified nano-magnetic iron oxide compounded prepolymer monomer;

[0118] Step (3): 90 parts of expanded perlite, 25 parts of silicate cement and 25 parts of microcapsule phase change unit were mixed uniformly, and an appropriate amount of water was added to form a slurry;

[0119] Step (4): Pour the slurry into the mold, compact it by vibrating, and then cure it at a temperature of 25°C and a humidity of 85% for 10 days. After demolding, the composite energy-saving material is obtained.

[0120] Comparative Example 5

[0121] The difference from Example 1 is that the microcapsule phase change unit is excessive:

[0122] A method for preparing a multifunctional composite energy-saving material for building envelope structure, comprising the following steps:

[0123] By weight parts:

[0124] Step (1): 100 parts of organic phase change material was heated to a molten state, 3 parts of emulsifier (fatty acid polyoxyethylene ester) was added, and high-speed shearing emulsification treatment was carried out for 15 min to obtain an emulsion with a particle size of 80-100 μm;

[0125] Step (2): 100 parts of silane-modified nano-magnetic iron oxide compounded prepolymer monomer and 4 parts of triethyl citrate were added to the emulsion obtained in step (1), and then stirred uniformly to carry out in-situ polymerization reaction. After cooling and solidification, the microcapsule phase change unit was obtained;

[0126] Step (2.1): 100 parts of nano-magnetic iron oxide (particle size 20 nm) was dispersed in 200 parts of a mixture of ethanol-water with a volume ratio of 3:1, 15 parts of silane coupling agent KH550 was added, and ultrasonic treatment was carried out at 60°C for 30 min, power 300W, to obtain a silanized modified nano-magnetic iron oxide dispersion;

[0127] Step (2.2): reacting 120 parts of melamine with 300 parts of a 37% formaldehyde solution at pH 8.5 and 75° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0128] Step (2.3): adding the dispersion obtained in step (2.1) to the melamine-formaldehyde prepolymer obtained in step (2.2), and stirring at a constant temperature of 65° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide;

[0129] Step (3): 90 parts of expanded perlite, 25 parts of Portland cement and 35 parts of microcapsule phase change units are mixed evenly, and an appropriate amount of water is added to stir to form a slurry;

[0130] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 25° C. and a humidity of 85% for 10 days. After demoulding, the composite energy-saving material is obtained.

[0131] Comparative Example 6

[0132] The difference from Example 1 is that the prepolymer monomer compounded with silane-modified nano-ferroferric oxide is not prepared in advance:

[0133] A method for preparing the multifunctional composite energy-saving material for building envelope structures comprises the following steps:

[0134] By weight:

[0135] Step (1): 100 parts of an organic phase change material are heated to a molten state, 3 parts of an emulsifier (polyoxyethylene fatty acid ester) are added, and high-speed shear emulsification treatment is performed for 15 minutes to obtain an emulsion with a particle size of 80-100 μm;

[0136] Step (2): adding 50 parts of silane-modified nano-ferroferric oxide dispersion, 85 parts of prepolymer monomer and 4 parts of triethyl citrate to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain microcapsule phase change units;

[0137] Step (2.1): Disperse 100 parts of nano-ferroferric oxide (particle size 20 nm) in 200 parts of a 3:1 ethanol-water mixture by volume, add 15 parts of a silane coupling agent KH550, and ultrasonically treat at 60°C for 30 minutes at a power of 300 W to obtain a silanized nano-ferroferric oxide dispersion;

[0138] Step (2.2): reacting 120 parts of melamine with 300 parts of a 37% formaldehyde solution at pH 8.5 and 75° C. for 40 minutes to produce a melamine-formaldehyde prepolymer;

[0139] Step (3): 90 parts of expanded perlite, 25 parts of Portland cement and 25 parts of microcapsule phase change units are mixed evenly, and appropriate amount of water is added to stir to form a slurry;

[0140] Step (4): pour the slurry into a mold, vibrate and compact it, and then maintain it at a temperature of 25° C. and a humidity of 85% for 10 days. After demoulding, the composite energy-saving material is obtained.

[0141] Material parameter detection method:

[0142] 1. Thermal conductivity: In accordance with GB / T 10294-2008 "Thermal insulation materials - Determination of steady-state thermal resistance and related properties - Guarded hot plate method" or GB / T 10295-2008 "Thermal insulation materials - Determination of steady-state thermal resistance and related properties - Heat flow meter method".

[0143] 2. Density: According to GB / T 5486-2008 "Test methods for inorganic rigid thermal insulation products", the mass and volume of the sample are measured after drying.

[0144] 3. Compression strength: Tested using a pressure testing machine in accordance with GB / T 5486-2008, Test methods for inorganic rigid thermal insulation products.

[0145] 4. GB / T 34477-2017 Acetone extraction weight loss method after hot and cold cycles.

[0146] Performance requirements: The thermal conductivity of the composite energy-saving material is 0.03-0.05W / (m·K), and the density is 300-500kg / m 3 , the compression strength is 0.5-1.2MPa.

[0147] The performance results are shown in Table 1.

[0148] Table 1

[0149] Group <![CDATA[密度(kg / m 3 )]]> Thermal conductivity (W / m·K) Compression strength (MPa) Leakage rate (%) Example 1 380±10 0.038 0.82 2.8 Example 2 360±15 0.04 0.75 3.1 Example 3 345±8 0.041 0.68 3.5 Example 4 400±12 0.036 0.93 2.5 Example 5 420±15 0.042 0.95 3.8 Comparative Example 1 290±10 0.068 1.2 - Comparative Example 2 365±8 0.061 0.73 19.3 Comparative Example 3 465±20 0.048 0.32 37.5 Comparative Example 4 380±10 0.038 0.82 2.8 Comparative Example 5 275±5 0.031 0.25 8.9 Comparative Example 6 370±12 0.059 0.57 31.7

[0150] In Examples 1-5, a pre-compounding process was used to form a chemically bonded thermally conductive network within the resin matrix using silanized nano-ferroferric oxide. The hydrolyzed groups of the silane coupling agent KH550 dehydrated and condensed with the hydroxyl groups on the surface of the ferroferric oxide, forming Fe-O-Si covalent bridges. Simultaneously, the alkane chains cross-linked with the hydroxyl groups of the melamine-formaldehyde resin, creating an integrated nanoparticle-resin framework. This structure produced a triple synergistic effect:

[0151] 1. Enhanced heat transfer: The ferroferric oxide core is directly coupled to the resin matrix through chemical bonds, eliminating interfacial phonon scattering and increasing the phonon mean free path to the lattice scale;

[0152] 2. Phase transition control and enhancement: Atomic-level roughness is formed on the surface of nanoparticles, acting as heterogeneous nucleation sites for paraffin wax, reducing the phase transition activation energy barrier;

[0153] 3. Structural stability guarantee: The chemically cross-linked network resists thermal stress deformation and inhibits the initiation of microcracks during phase change cycles.

[0154] In contrast, Comparative Example 1 suffers from a sluggish thermal response due to the lack of phase change units; Comparative Example 2, with its unmodified ferroferric oxide, creates a thermal barrier due to physical adsorption at the interface; Comparative Example 3, with its excessive ferroferric oxide, causes agglomeration and damages the cement matrix; Comparative Example 5, with its excessive phase change units, hinders cement hydration; and Comparative Example 6, with its step-by-step addition, leads to ferroferric oxide-resin debonding and high leakage. The essential difference lies in the fact that the chemically bonded network simultaneously achieves directional heat transfer and coordinated mechanical strain, whereas in the other comparative examples, due to interface defects or component imbalances, this synergistic mechanism is lost, resulting in reduced thermal conductivity, structural damage, or functional failure.

Claims

1. A multifunctional composite energy-saving material for building envelope structure, characterized in that: By weight, it comprises 90-110 parts of lightweight aggregate, 15-30 parts of cement-based binder and 15-30 parts of microcapsule phase change unit; The microcapsule phase change unit has a particle size of 50-200 μm and is composed of a core-shell structure, wherein the core is an organic phase change material with a phase change temperature of 20-30° C., and the shell is a cross-linked polymer layer doped with modified nano-ferrosoferric oxide.

2. The multifunctional composite energy-saving material for building envelope structure according to claim 1, characterized in that: The organic phase change material is one or more of paraffin, fatty acid or alcohol compounds; the cross-linked polymer layer is formed by an in-situ polymerization reaction of melamine-formaldehyde prepolymer compounded with silane-modified nano-ferroferric oxide and triethyl citrate; the lightweight aggregate is one or more of expanded perlite, ceramsite or foam glass; and the cement-based binder is silicate cement or sulphoaluminate cement.

3. A method for preparing a multifunctional composite energy-saving material for a building envelope structure according to any one of claims 1 to 2, characterized in that: The following steps are involved: By weight: Step (1): heating 100 parts of an organic phase change material to a molten state, adding 2-4 parts of an emulsifier and performing high-speed shear emulsification treatment to obtain an emulsion; Step (2): adding 100-120 parts of silane-modified nano-ferroferric oxide compounded prepolymer monomer and 3-5 parts of a cross-linking agent to the emulsion obtained in step (1), stirring evenly and then performing in-situ polymerization reaction, and cooling and solidifying to obtain a microcapsule phase change unit; Step (3): 90-110 parts of lightweight aggregate, 15-30 parts of cement-based binder and 15-30 parts of microcapsule phase change unit are mixed evenly, and water is added to stir to form a slurry; Step (4): pouring the slurry obtained in step (3) into a mold, vibrating and compacting it, and then curing it, and demoulding it to obtain a composite energy-saving material.

4. The method for preparing the multifunctional composite energy-saving material for building envelope structure according to claim 3, characterized in that: In the step (1), the emulsifier is a nonionic surfactant, and the emulsification time is 10-30 minutes.

5. The method for preparing the multifunctional composite energy-saving material for building envelope structure according to claim 3, characterized in that: In the step (4), the curing conditions are a temperature of 20-30° C., a humidity of 80% to 95%, and a curing time of 7-14 days.

6. The method for preparing the multifunctional composite energy-saving material for building envelope structure according to claim 3, characterized in that: The preparation process of the silane-modified nano-ferroferric oxide compounded prepolymer monomer is as follows: Step (2.1): dispersing 100 parts of nano-ferroferric oxide in 180-220 parts of an ethanol-water mixture with a volume ratio of 2-3:1, adding 15-17 parts of a silane coupling agent KH550, and ultrasonically treating at 60° C. for 30 minutes to obtain a silanized nano-ferroferric oxide dispersion; Step (2.2): reacting 100-140 parts of melamine with 300 parts of 37% formaldehyde solution at pH = 8-9 and 70-90° C. for 40 minutes to form a melamine-formaldehyde prepolymer; Step (2.3): Add the dispersion obtained in step (2.1) to the prepolymer in step (2.2), and stir at a constant temperature of 60-70° C. for 90 minutes to form a prepolymer monomer compounded with silane-modified nano-ferroferric oxide.

7. The method for preparing a multifunctional composite energy-saving material for a building envelope structure according to claim 3, wherein: The organic phase change material is one or more of paraffin, fatty acid or alcohol compounds; the lightweight aggregate is one or more of expanded perlite, ceramsite or foam glass; and the cement-based binder is silicate cement or sulphoaluminate cement.