A method for preparing a total heat exchange membrane

Abstract

This invention relates to the technical field of total heat exchange membranes and discloses a method for preparing a total heat exchange membrane, comprising the following steps: S1, vacuum aluminizing a porous base membrane to form an aluminum-coated layer on one side of the porous base membrane; S2, forming a porous structure on one side of the aluminum-coated layer by atomization with an acidic solution, wherein the porous area accounts for 50-90% of the total area of ​​the aluminum-coated layer; S3, coating a hydrophilic composite filler onto the opposite side of the aluminum-coated layer on the porous base membrane, filling the pores of the porous base membrane and forming a coating, and then drying to obtain a total heat exchange membrane. This invention improves the thermal conductivity and water vapor permeability of the total heat exchange membrane by setting an aluminum-coated layer and coating with a hydrophilic composite filler, thereby improving the total heat exchange efficiency, and the aluminum-coated layer also improves the mechanical properties.

Description

Technical Field

[0001] This invention relates to the technical field of total heat exchange membranes, and in particular to a method for preparing a total heat exchange membrane. Background Technology

[0002] As a core component of total heat exchangers, total heat exchange membranes play a crucial role in fresh air systems. Their core function is to exchange indoor and outdoor air temperature and humidity, achieving energy recovery between fresh outdoor air and polluted indoor air, thereby improving energy efficiency and achieving energy conservation and emission reduction goals. However, currently available total heat exchange membranes generally have some shortcomings. Specifically, their thermal conductivity is mostly in the range of 0.1-1.5 W / m·K, which is relatively low. Furthermore, their mechanical properties are not ideal, and their antibacterial, anti-mildew, and flame-retardant properties are also poor, which to some extent limits their practical application.

[0003] Chinese patent application CN 103877870 B discloses a total heat exchange membrane and a total heat exchanger with antibacterial and anti-mildew functions. The total heat exchange membrane includes a functional layer containing a polymer and antibacterial additives, and an optional support layer, with the functional layer composited on the support layer. This invention's total heat exchange membrane and total heat exchanger can effectively prevent the growth of bacteria, mold, and other organisms on the total heat exchange membrane during long-term use, providing fresh air, removing polluted and harmful air, and recovering HVAC energy. However, its thermal conductivity is still relatively low, failing to meet the requirements for efficient heat exchange, and it lacks good flame-retardant properties, thus limiting its long-term durability. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing a total heat exchange membrane. By aluminizing one side, its thermal conductivity is improved to meet the requirements of efficient heat exchange. At the same time, by filling the other side with a hydrophilic composite filler, it is ensured to have good moisture permeability, as well as antibacterial, anti-mildew, and flame-retardant properties. This improves the stability and durability of the total heat exchange membrane and expands its application range.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for preparing a total heat exchange membrane, comprising the following steps:

[0007] S1. Vacuum-deposit aluminum onto the porous base film to form an aluminum layer on one side of the porous base film;

[0008] S2. A porous structure is formed on one side of the aluminum plating layer by atomization with an acidic solution, and the obtained porous area accounts for 50-90% of the total area of ​​the aluminum plating layer.

[0009] S3. The hydrophilic composite filler is coated on the opposite side of the aluminum layer on the porous base membrane to fill the pores of the porous base membrane and form a coating. After drying, a total heat exchange membrane is obtained.

[0010] This invention significantly improves the thermal conductivity of a porous base membrane by forming a dense aluminum film through vacuum aluminizing. However, if aluminum is deposited on both sides of the porous base membrane, the flow rate during the exchange of indoor and outdoor air temperature and humidity will be greatly reduced. This also increases the resistance to water vapor permeation when subsequently coating with hydrophilic composite fillers and affects the adhesion of the fillers. Even if aluminum is deposited only on one side of the porous base membrane, the resistance to water vapor permeation still increases, thus affecting the total heat exchange efficiency. Therefore, it is necessary to control the area ratio of the porous structure after aluminizing to ensure that the total heat exchange membrane has both high thermal conductivity and high water vapor permeability. Furthermore, atomizing the aluminum film with an acidic solution makes the chemical reaction between metallic aluminum and the acid solution more active, making it easier to control the area ratio of the porous structure. After the porous base membrane with aluminizing is used to make a total heat exchange membrane, the aluminum will oxidize to form an alumina film. Alumina has good stability, which further improves the stability and durability of the total heat exchange membrane.

[0011] Preferably, the porous area accounts for 60-80% of the total area of ​​the aluminum-plated layer.

[0012] Preferably, the thickness of the porous base film is 10-100 μm, more preferably 10-30 μm.

[0013] Preferably, the basis weight of the porous base membrane is 10-100 g / m³. 2 More preferably 10-30 g / m 2 .

[0014] Preferably, the porous base membrane is made of one of the following materials: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyamide (PA), thermoplastic polyurethane (TPU), polyimide (PI), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF).

[0015] Preferably, the thickness of the aluminum film is 0.5-3 μm.

[0016] Preferably, the acidic solution is either hydrochloric acid or sulfuric acid, with a hydrogen ion concentration of 6-9 mol / L.

[0017] Preferably, the atomization jet angle is 10-15°, the distance between the nozzle and the surface of the porous base film is 40-80cm, the carrier gas is nitrogen, the nitrogen pressure is 2.5-4bar, the feed rate is 30-50L / min, and the acidic solution pressure is 1.5-3bar, the feed rate is 5-7L / h.

[0018] Preferably, the coating thickness of the hydrophilic composite filler is 1-200 μm, more preferably 10-40 μm.

[0019] Preferably, by mass percentage, the hydrophilic composite filler comprises 1-5% hygroscopic agent, 1-5% antibacterial and antifungal agent, 1-5% flame retardant and 1-5% hydrophilic polymer material, with the remainder being deionized water.

[0020] Preferably, the hydrophilic polymer material includes one or more of polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, and polydimethylacrylamide.

[0021] Preferably, the hygroscopic agent includes one or more of lithium chloride, calcium chloride, magnesium chloride, and glycerin.

[0022] Preferably, the antibacterial and antifungal agent includes one or more of quaternary ammonium salt antibacterial agents, chlorophenol antibacterial agents, guanidine antibacterial agents, catechins, ginkgo extract, and matrine.

[0023] Preferably, the flame retardant includes one or more phosphorus-nitrogen flame retardants.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The thermal conductivity of the total heat exchange membrane can be improved by the aluminum coating, thereby improving the sensible heat exchange efficiency, and the aluminum coating can also improve the mechanical properties.

[0026] (2) By filling the pores of the porous base membrane with a hydrophilic composite material, the water vapor permeation is increased and combined with the thermal conductivity of the aluminum coating, the total heat exchange efficiency can be further improved.

[0027] (3) By filling the pores of the porous base membrane with a hydrophilic composite filler, the added functional components can impart antibacterial, mildew-proof and flame-retardant properties to the total heat exchange membrane. Detailed Implementation

[0028] The technical solution of the present invention will be illustrated below with specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0029] The preparation of the total heat exchange membrane includes the following steps:

[0030] S1. Vacuum-deposit aluminum onto the porous base film to form an aluminum layer on one side of the porous base film;

[0031] S2. A porous structure is formed on one side of the aluminum plating layer by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution or a sulfuric acid solution with a hydrogen ion concentration of 6-9 mol / L. After drying, the porous area obtained accounts for 50-90% of the total area of ​​the aluminum plating layer.

[0032] S3. Coat the hydrophilic composite filler on the opposite side of the aluminum layer on the porous base membrane. The coating thickness of the hydrophilic composite filler is 1-200μm, so that the hydrophilic composite filler fills the pores of the porous base membrane. After drying, a total heat exchange membrane is obtained.

[0033] In a specific embodiment of the present invention, the thickness of the porous base film is 10-100 μm, and the basis weight is 10-100 g / m³. 2 The porous base membrane is made of one of the following materials: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyamide (PA), thermoplastic polyurethane (TPU), polyimide (PI), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF).

[0034] In a specific embodiment of the present invention, vacuum aluminum plating is a conventional aluminum plating process, which forms a dense aluminum film on the surface of a porous base film, with a thickness of 0.5-3 μm.

[0035] In a specific embodiment of the present invention, the atomizing jet angle is 10-15°, the distance between the nozzle and the porous base film surface is 40-80 cm, the carrier gas is nitrogen, the nitrogen pressure is 2.5-4 bar, and the feed rate is 30-50 L / min; the acidic solution pressure is 1.5-3 bar, and the feed rate is 5-7 L / h. The porous base film is placed vertically in front of the atomizing device, and the spray generated by the atomizing device is used for spraying. The aluminum plating layer on the surface of the porous base film is atomized by the acidic solution. The spraying amount per unit time is changed by adjusting the jet angle, nozzle distance, and feed rate, and the spraying position is changed by using a slide rail to make the atomizing device move linearly at a uniform speed, thereby forming a porous structure. The porous area percentage is calculated as follows: the weight of the porous base film is A (g), the weight of the porous base film after aluminum plating is X1 (g), the weight of the porous base film after atomization is X2 (g), and the porous area percentage (%) = (X2-X1) / (X1-A)*100%.

[0036] In a specific embodiment of the present invention, the hydrophilic composite filler, by mass percentage, comprises 1-5% of a hygroscopic agent, 1-5% of an antibacterial and antifungal agent, 1-5% of a flame retardant, and 1-5% of a hydrophilic polymer, with the remainder being deionized water. In a specific embodiment of the present invention, the hydrophilic polymer includes one or more of polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, and polydimethylacrylamide. The hygroscopic agent includes one or more of lithium chloride, calcium chloride, magnesium chloride, and glycerin. The antibacterial and antifungal agent includes one or more of quaternary ammonium salt antibacterial agents, chlorophenol antibacterial agents, guanidine antibacterial agents, catechins, ginkgo extract, and matrine. The flame retardant includes one or more of phosphorus-nitrogen flame retardants (cyclic phosphates, tripolyphosphates, and ammonium polyphosphates).

[0037] Example 1

[0038] The preparation of the total heat exchange membrane includes the following steps:

[0039] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0040] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 50.8% of the total area of ​​the aluminum-coated layer.

[0041] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0042] Example 2

[0043] The preparation of the total heat exchange membrane includes the following steps:

[0044] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0045] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 62.3% of the total area of ​​the aluminum-coated layer.

[0046] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0047] Example 3

[0048] The preparation of the total heat exchange membrane includes the following steps:

[0049] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0050] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 71.5% of the total area of ​​the aluminum-coated layer.

[0051] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0052] Example 4

[0053] The preparation of the total heat exchange membrane includes the following steps:

[0054] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film;

[0055] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 80.1% of the total area of ​​the aluminum-coated layer.

[0056] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0057] Example 5

[0058] The preparation of the total heat exchange membrane includes the following steps:

[0059] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0060] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 89.9% of the total area of ​​the aluminum-coated layer.

[0061] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0062] Example 6

[0063] The difference from Example 3 is that the thickness of the aluminum plating layer is 1.5 μm.

[0064] The preparation of the total heat exchange membrane includes the following steps:

[0065] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1.5μm on one side of the PE base film.

[0066] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 70.7% of the total area of ​​the aluminum-coated layer.

[0067] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0068] Example 7

[0069] The difference from Example 3 is that the thickness of the aluminum plating layer is 2 μm.

[0070] The preparation of the total heat exchange membrane includes the following steps:

[0071] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 2μm on one side of the PE base film.

[0072] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 69.8% of the total area of ​​the aluminum-coated layer.

[0073] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0074] Example 8

[0075] The difference from Example 3 is that the coating thickness of the hydrophilic composite filler is 10 μm.

[0076] The preparation of the total heat exchange membrane includes the following steps:

[0077] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0078] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 71.7% of the total area of ​​the aluminum-coated layer.

[0079] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 10 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0080] Example 9

[0081] The difference from Example 3 is that the coating thickness of the hydrophilic composite filler is 40 μm.

[0082] The preparation of the total heat exchange membrane includes the following steps:

[0083] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0084] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 71.4% of the total area of ​​the aluminum-coated layer.

[0085] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 40 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0086] Example 10

[0087] The difference from Example 3 is in the composition of the hydrophilic composite filler and the coating thickness.

[0088] The preparation of the total heat exchange membrane includes the following steps:

[0089] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0090] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 72.0% of the total area of ​​the aluminum-coated layer.

[0091] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 4% polyvinyl alcohol, 3% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 3% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 40 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0092] Example 11

[0093] The difference from Example 3 is that the porous base film has a thickness of 30 μm and a basis weight of 20 g / m³. 2 .

[0094] The preparation of the total heat exchange membrane includes the following steps:

[0095] S1, A material with a thickness of 30μm and a basis weight of 20g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0096] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 71.8% of the total area of ​​the aluminum-coated layer.

[0097] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0098] Comparative Example 1

[0099] The difference from Example 3 is that aluminum plating was not performed.

[0100] The preparation of the total heat exchange membrane includes the following steps:

[0101] The hydrophilic composite filler was coated on a substrate with a thickness of 25 μm and a basis weight of 25 g / m². 2 On one side of the porous PE-based membrane, the hydrophilic composite filler, by mass percentage, comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, filling the pores. After drying, a total heat exchange membrane is obtained.

[0102] Comparative Example 2

[0103] The difference from Example 3 is that the thickness of the aluminum plating is 5 μm.

[0104] The preparation of the total heat exchange membrane includes the following steps:

[0105] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 5μm on one side of the PE base film.

[0106] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 71.3% of the total area of ​​the aluminum-coated layer.

[0107] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 20 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0108] Comparative Example 3

[0109] The difference from Example 3 is that the thickness of the hydrophilic composite filler coating is 100 μm.

[0110] The preparation of the total heat exchange membrane includes the following steps:

[0111] S1, A 25μm thick material with a basis weight of 15g / m 2 The porous PE base film is placed in a vacuum aluminizing machine for vacuum aluminizing, forming an aluminum layer with a thickness of 1μm on one side of the PE base film.

[0112] S2. A porous structure is formed on one side of the aluminum-coated layer of the porous base film by atomization with an acidic solution. The acidic solution is a hydrochloric acid solution with a hydrogen ion concentration of 8 mol / L. Atomization is performed at the center of the aluminum-coated film with a spray angle of 13° and a nozzle distance of 60 cm from the surface of the porous base film. The carrier gas is nitrogen with a pressure of 3 bar and a feed rate of 48 L / min. The acidic solution has a pressure of 2 bar and a feed rate of 6.8 L / h. After drying, the obtained porous area accounts for 71.5% of the total area of ​​the aluminum-coated layer.

[0113] S3. A hydrophilic composite filler is coated onto the opposite side of the aluminum-plated layer on the porous base membrane. By mass percentage, the hydrophilic composite filler comprises 3% polyvinyl alcohol, 2% calcium chloride, 3% quaternary ammonium salt antibacterial agent (dodecyltrimethylammonium chloride), and 2% phosphorus-nitrogen flame retardant (tripolyphosphate), with the remainder being deionized water. The coating thickness of the hydrophilic composite filler is 100 μm, ensuring that the hydrophilic composite filler fills the pores. After drying, a total heat exchange membrane is obtained.

[0114] Testing standards:

[0115] Water vapor permeability: GB / T 1037-2021, 38℃, 90%RH;

[0116] Thermal conductivity: ISO 22007-2-2008;

[0117] Tensile strength: GB / T 1040.2-2022.

[0118] Table 1

[0119]

[0120]

[0121] As shown in Table 1, this invention improves the thermal conductivity of the total heat exchange membrane by using an aluminum plating layer. By filling the pores of the porous base membrane with a hydrophilic composite filler, the water vapor transmission rate is increased, thereby further improving the total heat exchange efficiency. The aluminum plating layer also enhances the mechanical properties. Examples 1-5 demonstrate that as the porous area gradually increases relative to the total area of ​​the aluminum plating layer, the water vapor transmission rate of the total heat exchange membrane increases, and the thermal conductivity decreases, but it is still significantly higher than the thermal conductivity of conventional total heat exchange membranes (without aluminum plating) in the prior art. Comparative Example 1 also shows that although aluminum plating of the porous base membrane in this invention reduces the water vapor transmission rate, subsequent acidic solution atomization and hydrophilic composite filler coating can balance the water vapor transmission rate and thermal conductivity, resulting in a high overall performance of the total heat exchange membrane. Examples 3 and 6-7 show that the greater the thickness of the aluminum-coated layer, the smaller the fluctuation in thermal conductivity due to the fixed porous area formed by controlled atomization, but it will affect the water vapor transmission rate to some extent. Comparative Example 2 also shows that excessively thick aluminum-coated layers will lead to excessively low water vapor transmission rate, with no significant improvement in thermal conductivity, and will result in excessively high costs. Examples 3 and 8-10 show that the coating thickness of the hydrophilic composite filler affects the water vapor transmission rate, and the excessive thickness in Comparative Example 3 will also have a significant impact on thermal conductivity. Examples 3 and 11 show that increasing the thickness of the porous base film will reduce the water vapor transmission rate, and increasing the thickness will also affect the thermal conductivity.

[0122] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a total heat exchange membrane, characterized in that, Includes the following steps: S1. Vacuum-deposit aluminum onto the porous base film to form an aluminum layer on one side of the porous base film; S2. A porous structure is formed on one side of the aluminum plating layer by atomization with an acidic solution, and the porous area accounts for 50-90% of the total area of ​​the aluminum plating layer. S3. The hydrophilic composite filler is coated on the opposite side of the aluminum layer on the porous base membrane to fill the pores of the porous base membrane and form a coating. After drying, a total heat exchange membrane is obtained.

2. The method for preparing the total heat exchange membrane according to claim 1, characterized in that, The thickness of the porous base film is 10-100 μm.

3. The method for preparing the total heat exchange membrane according to claim 1, characterized in that, The acidic solution is either hydrochloric acid or sulfuric acid.

4. The method for preparing the total heat exchange membrane according to any one of claims 1-3, characterized in that, The atomization jet angle is 10-15°, the distance between the nozzle and the surface of the porous base film is 40-80cm, the carrier gas is nitrogen, the nitrogen pressure is 2.5-4bar, and the acidic solution pressure is 1.5-3bar.

5. The method for preparing the total heat exchange membrane according to any one of claims 1-3, characterized in that, The coating thickness of the hydrophilic composite filler is 1-200 μm.

6. The method for preparing the total heat exchange membrane according to claim 1, characterized in that, By mass percentage, the hydrophilic composite filler comprises 1-5% hygroscopic agent, 1-5% antibacterial and antifungal agent, 1-5% flame retardant and 1-5% hydrophilic polymer material, with the remainder being deionized water.

7. The method for preparing the total heat exchange membrane according to claim 6, characterized in that, The hydrophilic polymer material includes one or more of polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, and polydimethylacrylamide.

8. The method for preparing the total heat exchange membrane according to claim 6, characterized in that, The hygroscopic agent includes one or more of lithium chloride, calcium chloride, magnesium chloride, and glycerin.

9. The method for preparing the total heat exchange membrane according to any one of claims 6-8, characterized in that, The antibacterial and antifungal agents include one or more of the following: quaternary ammonium salt antibacterial agents, chlorophenol antibacterial agents, guanidine antibacterial agents, catechins, ginkgo extract, and matrine.

10. The method for preparing the total heat exchange membrane according to any one of claims 6-8, characterized in that, The flame retardant includes one or more phosphorus-nitrogen flame retardants.

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