Preparation process of air triggered HFO self-condensing refrigerant

Abstract

The application provides a preparation process of an air-triggered HFO self-curing refrigerant. The refrigerant comprises an HFO body and a composite additive; the composite additive comprises a first additive and a second additive; the first additive is a fluorine-containing acrylate oligomer; the second additive is composed of microencapsulated peroxide and an organic titanium chelate; the microencapsulated peroxide is prepared by using polyvinylidene fluoride as a wall material and t-butyl hydroperoxide as a core material through solvent evaporation, solidification and drying, and then the microencapsulated peroxide is compounded with the organic titanium chelate into the second additive under the protection of nitrogen; finally, the first additive and the second additive are added into the HFO body, and high-speed shearing mixing is performed to obtain the refrigerant. The refrigerant utilizes a pressure and oxygen double synergistic triggering mechanism to quickly form a gel sealing layer at the moment of leakage, and has excellent storage stability, rapid responsiveness and high sealing efficiency.

Description

Technical Field

[0001] This invention relates to the field of refrigerant technology, specifically to a preparation process for an air-triggered HFO self-condensing refrigerant. Background Technology

[0002] Hydrofluoroolefin (HFO) refrigerants, with their zero ozone depletion potential and low global warming potential, have become the mainstream alternative to traditional chlorofluorocarbon (CFC) refrigerants and are widely used in refrigeration equipment such as air conditioners, cold storage facilities, and cold chain logistics. However, leakage has always been a pain point in the industry. Leaks not only lead to decreased refrigeration efficiency and increased energy consumption, but also cause equipment downtime, increased maintenance costs, and even safety or environmental risks in certain chemical scenarios. Traditional solutions mostly rely on passive protection, such as pre-installing gaskets or applying sealant at equipment and pipe joints, or shutting down for maintenance after a leak occurs. However, pre-installed sealing layers will fail as the equipment ages and cannot proactively respond to leaks immediately; while post-leak repairs often delay the process, by which time the leak has already caused significant damage.

[0003] To address these issues, the industry has recently begun exploring the integration of self-healing or self-sealing functions into refrigerant systems, aiming to achieve intelligent protection by sealing leaks immediately. For example, Chinese patent application CN202510556638.1 discloses an ultra-low VOC waterborne coating that achieves rapid curing and resistance to media corrosion through modified acrylic-polyurethane hybrid emulsions and other components. This technological approach can indirectly inspire the introduction of functional resins into refrigerant systems. However, such coatings are independent external coatings that still need to be pre-applied to the equipment surface. Their curing trigger depends on the physical conditions during application and cannot be autonomously activated in the sudden and localized scenario of refrigerant leakage.

[0004] Another type of existing technology attempts to achieve controllable response by introducing materials sensitive to external stimuli. For example, Chinese patent application CN202510677438.1 discloses a composite flocculant containing a cationic etherifying agent, which adopts a photoresponsive azobenzene structure and can regulate its molecular configuration under ultraviolet light irradiation. Such photoresponsive materials have exploratory value in the field of smart materials, but they have obvious limitations when applied to refrigerant leakage scenarios: leakage often occurs outside the equipment and in unattended environments, making it impossible to guarantee the timely provision of external stimuli such as ultraviolet light; at the same time, the compatibility of such materials with refrigerant media and their stability in high-pressure closed environments require complex adaptation and modification, making it difficult to achieve immediate use.

[0005] It is evident that existing technologies struggle to simultaneously meet the dual requirements of storage stability and timely response. While excessively active additives can ensure rapid response in case of leakage, they are prone to premature degradation during preparation and storage. Conversely, sacrificing activity to ensure storage stability results in an excessively slow response time, failing to achieve second-level emergency sealing. Therefore, maintaining the original properties of the refrigerant while ensuring the additive remains chemically inert under storage and normal operating conditions, and enabling rapid and reliable activation upon leakage, has become a pressing technical challenge in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a preparation process for an air-triggered HFO self-condensing refrigerant, thereby solving the technical problem that "existing self-healing refrigerants cannot simultaneously ensure storage stability and timely response to leaks".

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides an air-triggered HFO self-condensing refrigerant, the refrigerant comprising an HFO matrix and a composite additive; the composite additive comprising a first additive and a second additive; the first additive being a fluorinated acrylate oligomer; and the second additive being composed of microencapsulated peroxide and an organotitanium chelate.

[0008] Furthermore, the fluorinated acrylate oligomer is a fluorinated acrylate oligomer with a molecular weight of 1000~3000. The fluorinated groups in the molecular chain ensure compatibility with HFO. The terminal unsaturated double bonds (C=C) and hydroxyl groups (-OH) provide active centers. At the leakage interface, the peroxide released by the microcapsule is catalyzed by the free radicals generated by the decomposition of the organotitanium chelate, which initiates a cross-linking polymerization reaction, causing the system to form a thixotropic gel within seconds, thereby achieving rapid sealing of the leakage point.

[0009] Furthermore, the microencapsulated peroxide is prepared using polyvinylidene fluoride as the wall material and peroxide as the core material, employing a raw material system comprising sorbitan monooleate and liquid paraffin.

[0010] Furthermore, the organotitanium chelate is tetrabutyl titanate, which is essentially a Lewis acid. Prior to leakage, it remains chemically inert in a dry HFO system. When leakage occurs, the water vapor at the interface rapidly undergoes a coordination hydrolysis reaction with the tetrabutyl titanate, releasing its titanium centers (Ti). 4+ It accepts the lone pair electrons from the oxygen atom in a water molecule to generate an active Ti-OH species. This process is the activation of a Lewis acid by a Lewis base. The activated titanium species has strong Lewis acidity and can efficiently catalyze subsequent peroxide decomposition and polymerization cross-linking reactions.

[0011] Secondly, the present invention provides a preparation process for an air-triggered HFO self-condensing refrigerant, comprising the following steps: (1) Polyvinylidene fluoride is dissolved in N,N-dimethylformamide to form an oil phase. Liquid paraffin and tert-butyl hydrogen peroxide aqueous solution are mixed to form a W / O type primary emulsion. The oil phase is added to the primary emulsion. After solvent evaporation and curing, and drying, microencapsulated peroxide is obtained. (2) Under nitrogen protection, the microencapsulated peroxide obtained in step (1) and the organotitanium chelate are mixed and compounded to prepare the second additive; (3) Add a composite additive consisting of the first additive and the second additive mentioned above to the HFO body, and mix them by high-speed shearing and stirring to obtain a refrigerant; Specifically, in step (1), the mass ratio of polyvinylidene fluoride to N,N-dimethylformamide is 1:(4.3~4.8).

[0012] Specifically, in step (1), the mass ratio of liquid paraffin to tert-butyl hydrogen peroxide aqueous solution is (5.73~6.8):1.

[0013] Specifically, the HFO body mentioned in step (3) is a mixture of R1234yf and R1234ze, with a mass ratio of R1234yf to R1234ze of (0.5~1):1.

[0014] Specifically, the mass fraction of the tert-butyl hydrogen peroxide aqueous solution in step (3) is 60-80%.

[0015] Specifically, the total mass of the composite additive accounts for 3 to 5.5% of the total mass of HFO, wherein the amount of the first additive accounts for 1.5 to 3% of the total mass of HFO, the amount of the microencapsulated peroxide in the second additive accounts for 1 to 1.5% of the total mass of HFO, and the amount of the organotitanium chelate accounts for 0.5 to 1% of the total mass of HFO.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) This invention uses microencapsulation technology to encapsulate peroxides in polyvinylidene fluoride wall materials, thus constructing a dual synergistic triggering mechanism of pressure and oxygen. Under storage and normal operating conditions, the system remains chemically inert and has excellent long-term stability; at the moment of leakage, the sudden drop in pressure and the increase in oxygen partial pressure synergistically induce the microcapsule to rupture, rapidly releasing the active components and achieving a self-sealing response within seconds, effectively solving the bottleneck problem of difficulty in balancing storage stability and leakage response speed in the prior art.

[0017] (2) The present invention uses fluorinated acrylate oligomers as crosslinking matrix. Its molecular chain fluorinated structure ensures good compatibility with HFO body. The terminal active groups crosslink rapidly after triggering to form a dense elastic sealing layer. The refrigeration efficiency recovery rate after leakage can reach more than 99%. The sealing layer maintains stable mechanical properties in a wide temperature range of -45~130℃ and salt spray environment, and has both excellent sealing effect and environmental tolerance.

[0018] (3) This invention introduces an organic titanium chelate as a catalyst, which remains inert in the dry HFO system. Upon encountering water vapor at the leakage interface, it undergoes a coordination hydrolysis reaction to generate active titanium species, significantly improving the peroxide decomposition efficiency and polymerization rate, shortening the response time to 4-6 seconds, and simultaneously enhancing the crosslinking density and structural stability of the sealing layer. This preparation process is simple and controllable, can be directly added to existing refrigeration equipment, and has good industrial applicability. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a preparation process for an air-triggered HFO self-condensing refrigerant. By adding a composite additive composed of fluoroacrylate oligomers (trifluoroethyl acrylate homopolymers), microencapsulated peroxides, and organic titanium chelates (tetrabutyl titanate) to the HFO refrigerant, a homogeneous and compatible system is formed. This system is directly added to the equipment as a refrigerant. During normal operation, the system remains stable under high pressure and low oxygen conditions inside the equipment, maintaining the original refrigeration and heat transfer performance of HFO. When HFO leaks, the pressure at the leak point instantly drops from high pressure to atmospheric pressure, and the oxygen partial pressure rises sharply from near zero to atmospheric levels. This dual abrupt change triggers rapid swelling and rupture of the microcapsule wall material, releasing the peroxide. This establishes a mechanism of instantaneous synergistic triggering by pressure and oxygen, achieving the effect of maintaining refrigerant stability under storage and normal operating conditions, and rapidly responding to self-sealing only in the event of a leak. Its core mechanism lies in the following: Polyvinylidene fluoride (PVDF) is used as the wall material of microcapsules to physically encapsulate the peroxides. Under the high-pressure, low-oxygen environment of preparation and storage, the PVDF wall material remains stable and intact, isolating the peroxides from the system and ensuring storage stability. When a refrigerant leak occurs, the pressure at the leak point instantly drops from the system's high pressure (≥0.5 MPa) to atmospheric pressure, while the oxygen partial pressure rapidly increases from a near-anaerobic environment to atmospheric levels (21 kPa). This synergistic abrupt change causes the PVDF microcapsules to swell and rupture within seconds, releasing the peroxides. Water vapor and organic matter at the leak interface... Titanium chelate (tetrabutyl titanate) undergoes a coordination hydrolysis reaction, activating its Lewis acid activity, catalyzing the decomposition of peroxides to generate free radicals, and initiating the cross-linking polymerization of fluorinated acrylate oligomers. This first forms a thixotropic gel within 3-8 seconds for emergency sealing, and then gradually solidifies into an elastic sealing layer within 15-30 minutes. This technical solution, through a design of first achieving steady-state isolation and then transient synergistic triggering, solves the technical problem that existing self-healing refrigerants cannot simultaneously ensure storage stability and timely leakage response. It achieves a smart self-sealing function that ensures stable storage under normal conditions and rapid response in case of leakage. The invention will be further described below with reference to specific embodiments.

[0021] This invention provides a preparation process for an air-triggered HFO self-condensing refrigerant, comprising the following steps: (1) Dissolve 100-130g of polyvinylidene fluoride in 500-600mL of N,N-dimethylformamide, heat and stir at 60-65℃ until completely dissolved, and use as the oil phase; add 15-16.4g of dehydrated sorbitan monooleate to 650-680mL of liquid paraffin and stir to mix, then slowly add 80-95g of 60-80% tert-butyl hydrogen peroxide aqueous solution, and emulsify at 8000rpm for 15-2 minutes. 0 min, forming a W / O type primary emulsion; slowly add the oil phase to the above primary emulsion, stir at 1000 r / min for 10~15 min to form a composite emulsion, heat to 70~80℃, remove N,N-dimethylformamide by vacuum distillation for 1~2 h, so that polyvinylidene fluoride precipitates and deposits on the surface of the core material to form the wall material, after cooling, pour off the upper oil phase, filter, wash with n-hexane 3 times, collect the filter cake, and vacuum dry at 40℃ for 12 h to obtain microencapsulated peroxide; (2) Under a nitrogen protective atmosphere, microencapsulated peroxide and tetrabutyl titanate are mixed at a mass ratio of (1~3):1 and mixed at a speed of 100~200 r / min for 15~20 min to obtain the second additive, which is sealed and stored in the dark for later use. (3) At -30℃ and normal pressure, add 0.075~0.15kg of trifluoroethyl acrylate homopolymer (molecular weight 1000~3000) and 0.075~0.125kg of second additive to 5kg of HFO bulk, start the high-speed shear machine to stir and mix, and obtain refrigerant.

[0022] Preferably, the HFO body is a mixture of R1234yf and R1234ze, with the mass ratio of R1234yf to R1234ze being (0.5~1):1.

[0023] Preferably, the molecular weight of the trifluoroethyl acrylate homopolymer is 1000~3000.

[0024] Preferably, the process parameters of the high-speed shearing machine are: working temperature of 25℃, rotation speed of 3000~5000r / min, and time of 20~30min, to ensure that the additives and HFO are completely miscible and do not agglomerate.

[0025] According to the present invention, the permeability of the microcapsules can be adjusted by changing the conditions for the polymerization wall and by changing the size characteristics of the microcapsules. The particle size of the microcapsules can be between 1 μm and 20 μm, preferably between 1 μm and 10 μm, the wall thickness is preferably between 0.2 μm and 0.5 μm, and the encapsulation efficiency is ≥85%.

[0026] Example 1; (1) Dissolve 100g of polyvinylidene fluoride in 500mL of N,N-dimethylformamide and heat and stir at 60℃ until completely dissolved to obtain the oil phase; add 15g of dehydrated sorbitan monooleate to 650mL of liquid paraffin and stir to mix, slowly add 80g of 60% tert-butyl hydrogen peroxide aqueous solution, and emulsify at 8000rpm for 15min to form a W / O type primary emulsion; slowly add the oil phase to the above primary emulsion and stir at 1000r / min for 10min to form a composite emulsion, heat to 70℃, and remove N,N-dimethylformamide by vacuum distillation for 1h, so that polyvinylidene fluoride precipitates and deposits on the surface of the core material to form the wall material. After cooling, pour off the upper oil phase, filter, wash with n-hexane 3 times, collect the filter cake, and vacuum dry at 40℃ for 12h to obtain microencapsulated peroxide; (2) Under a nitrogen protective atmosphere, microencapsulated peroxide and tetrabutyl titanate were mixed at a mass ratio of 1:1 and mixed at a speed of 100 r / min for 15 min to obtain the second additive, which was sealed and stored in the dark for later use. (3) Select R1234yf and R1234ze at a mass ratio of 0.5:1 as HFO body. Under normal pressure at -30℃, add 0.075kg of trifluoroethyl acrylate homopolymer (molecular weight 1000) and 0.1kg of second additive to 5kg of HFO body. Start the high-speed shear mixer to stir at 3000r / min for 20min to obtain refrigerant.

[0027] Example 2; (1) Dissolve 115g of polyvinylidene fluoride in 550mL of N,N-dimethylformamide and heat and stir at 62℃ until completely dissolved to obtain the oil phase; add 15.8g of dehydrated sorbitan monooleate to 660mL of liquid paraffin and stir to mix, slowly add 86g of 70% tert-butyl hydrogen peroxide aqueous solution, and emulsify at 8000rpm for 18min to form a W / O type primary emulsion; slowly add the oil phase to the above primary emulsion and stir at 1000r / min for 12min to form a composite emulsion, heat to 75℃, and remove N,N-dimethylformamide by vacuum distillation for 1.5h, so that polyvinylidene fluoride precipitates and deposits on the surface of the core material to form the wall material, cool and pour off the upper oil phase, filter, wash with n-hexane 3 times, collect the filter cake, and vacuum dry at 40℃ for 12h to obtain microencapsulated peroxide; (2) Under a nitrogen protective atmosphere, microencapsulated peroxide and tetrabutyl titanate were mixed at a mass ratio of 1.5:1 and mixed at a speed of 150 r / min for 18 min to obtain the second additive, which was sealed and stored in the dark for later use. (3) Select R1234yf and R1234ze at a mass ratio of 0.8:1 as HFO body. Under normal pressure at -30℃, add 0.1kg of trifluoroethyl acrylate homopolymer (molecular weight 2000) and 0.1kg of second additive to 5kg of HFO body, start the high-speed shear mixer to stir at 4000r / min for 25min to obtain refrigerant.

[0028] Example 3; (1) Dissolve 130g of polyvinylidene fluoride in 600mL of N,N-dimethylformamide and heat and stir at 65℃ until completely dissolved to obtain the oil phase; add 16.4g of dehydrated sorbitan monooleate to 680mL of liquid paraffin and stir to mix, slowly add 95g of 80% tert-butyl hydrogen peroxide aqueous solution, and emulsify at 8000rpm for 20min to form a W / O type primary emulsion; slowly add the oil phase to the above primary emulsion and stir at 1000r / min for 15min to form a composite emulsion, heat to 80℃, and remove N,N-dimethylformamide by vacuum distillation for 2h, so that polyvinylidene fluoride precipitates and deposits on the surface of the core material to form the wall material, cool and pour off the upper oil phase, filter, wash with n-hexane 3 times, collect the filter cake, and vacuum dry at 40℃ for 12h to obtain microencapsulated peroxide; (2) Under a nitrogen protective atmosphere, microencapsulated peroxide and tetrabutyl titanate were mixed at a mass ratio of 3:1 and mixed at a speed of 200 r / min for 20 min to obtain the second additive, which was sealed and stored in the dark for later use. (3) Select R1234yf and R1234ze in a mass ratio of 1:1 as HFO body. Under normal pressure at -30℃, add 0.15kg of trifluoroethyl acrylate homopolymer (molecular weight 3000) and 0.1kg of second additive to 5kg of HFO body. Start the high-speed shear mixer to stir at 5000r / min for 20~30min to obtain refrigerant.

[0029] Example 4; (1) Dissolve 115g of polyvinylidene fluoride in 550mL of N,N-dimethylformamide and heat and stir at 62℃ until completely dissolved to obtain the oil phase; add 15.8g of dehydrated sorbitan monooleate to 660mL of liquid paraffin and stir to mix, slowly add 86g of 70% tert-butyl hydrogen peroxide aqueous solution, and emulsify at 8000rpm for 18min to form a W / O type primary emulsion; slowly add the oil phase to the above primary emulsion and stir at 1000r / min for 12min to form a composite emulsion, heat to 75℃, and remove N,N-dimethylformamide by vacuum distillation for 1.5h, so that polyvinylidene fluoride precipitates and deposits on the surface of the core material to form the wall material, cool and pour off the upper oil phase, filter, wash with n-hexane 3 times, collect the filter cake, and vacuum dry at 40℃ for 12h to obtain microencapsulated peroxide; (2) Under a nitrogen protective atmosphere, microencapsulated peroxide and tetrabutyl titanate were mixed at a mass ratio of 2:1 and mixed at a speed of 150 r / min for 18 min to obtain the second additive, which was sealed and stored in the dark for later use. (3) Select R1234yf and R1234ze at a mass ratio of 0.8:1 as HFO body. Under normal pressure at -30℃, add 0.1kg of trifluoroethyl acrylate homopolymer (molecular weight 2000) and 0.075kg of second additive to 5kg of HFO body. Start the high-speed shear mixer to stir at 4000r / min for 25min to obtain refrigerant.

[0030] Example 5; (1) Dissolve 115g of polyvinylidene fluoride in 550mL of N,N-dimethylformamide and heat and stir at 62℃ until completely dissolved to obtain the oil phase; add 15.8g of dehydrated sorbitan monooleate to 660mL of liquid paraffin and stir to mix, slowly add 86g of 70% tert-butyl hydrogen peroxide aqueous solution, and emulsify at 8000rpm for 18min to form a W / O type primary emulsion; slowly add the oil phase to the above primary emulsion and stir at 1000r / min for 12min to form a composite emulsion, heat to 75℃, and remove N,N-dimethylformamide by vacuum distillation for 1.5h, so that polyvinylidene fluoride precipitates and deposits on the surface of the core material to form the wall material, cool and pour off the upper oil phase, filter, wash with n-hexane 3 times, collect the filter cake, and vacuum dry at 40℃ for 12h to obtain microencapsulated peroxide; (2) Under a nitrogen protective atmosphere, microencapsulated peroxide and tetrabutyl titanate were mixed at a mass ratio of 1.5:1 and mixed at a speed of 150 r / min for 18 min to obtain the second additive, which was sealed and stored in the dark for later use. (3) R1234yf and R1234ze were mixed at a mass ratio of 0.8:1 as HFO body. Under normal pressure at -30℃, 0.125kg of trifluoroethyl acrylate homopolymer (molecular weight 2000) and 0.1kg of second additive were added to 5kg of HFO body. The high-speed shear mixer was started and stirred at a speed of 4000r / min for 25min to obtain refrigerant.

[0031] Comparative Example 1; The only difference between Comparative Example 1 and Example 2 is that step (1) is omitted, and step (2) is modified as follows: under a nitrogen protective atmosphere, tert-butyl hydrogen peroxide and tetrabutyl titanate are mixed at a mass ratio of 1.5:1 and mixed at a speed of 150 r / min for 18 min to obtain a composite additive, which is sealed and stored in the dark for later use. The remaining steps are the same as in Example 2.

[0032] Comparative Example 2; The difference between Comparative Example 2 and Example 2 is that step (2) is omitted, and step (3) is modified as follows: R1234yf and R1234ze are mixed at a mass ratio of 0.8:1 as HFO body. Under normal pressure at -30℃, 0.1 kg of trifluoroethyl acrylate homopolymer (molecular weight 2000) and 0.1 kg of microencapsulated peroxide are added to 5 kg of HFO body. The high-speed shear mixer is started and stirred at a speed of 4000 r / min for 25 min to obtain the refrigerant. The remaining steps are the same as in Example 2.

[0033] Comparative Example 3; The only difference between Comparative Example 3 and Example 2 is the difference in step (3). Step (3) is modified as follows: R1234yf and R1234ze are mixed at a mass ratio of 0.8:1 as HFO body. Under normal pressure at -30℃, 0.2kg of the second additive is added to 5kg of HFO body. The high-speed shear machine is started to stir at a speed of 4000r / min for 25min to obtain the refrigerant. The remaining steps are the same as in Example 2.

[0034] Test method: The refrigerants prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to the following performance tests.

[0035] Leakage test: The refrigerant sample was filled into a sealed test tank pressurized to 2.0 MPa with an oxygen content of less than 100 ppm. The tank was run stably for 30 minutes under standard operating conditions. The average cooling capacity before leakage was recorded. The sample was then depressurized to atmospheric pressure within 0.5 seconds using a controllable valve and exposed to air (temperature 25℃, relative humidity 50%) to simulate leakage. The response process of the sample forming a thixotropic gel that can block the leakage was observed, and the response time was recorded. The curing time from the start of depressurization to the complete curing of the gel into an elastic sealing layer was recorded. The specific results are shown in Table 1.

[0036] Curing test: After curing, record the average cooling capacity after leak sealing and calculate the cooling efficiency recovery rate. Cooling efficiency recovery rate = average cooling capacity after leak sealing / average cooling capacity before leak × 100%. Use a Shore hardness tester (Type A) to measure the hardness of the sealing layer. Gradually apply air pressure to the cured sealing layer and record the pressure value when it ruptures. The specific results are shown in Table 1.

[0037] High and low temperature stability test of sealing layer ratio: The cured sealing layer sample was placed in a -45℃ low temperature test chamber for 72 hours, and then removed to recover at room temperature for 2 hours. The sample was observed for cracking, powdering, peeling and other phenomena, and the deviation of Shore hardness from the initial value was tested. The sample was placed in a 130℃ high temperature oven for 72 hours, and then removed to recover at room temperature for 2 hours. The sample was observed for softening, flowing, deformation, cracking and other phenomena, and the deviation of Shore hardness from the initial value was tested. The specific results are shown in Table 2.

[0038] Salt spray corrosion resistance test of the sealing layer: The test was conducted according to GB / T10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test" standard. Test conditions: Neutral salt spray test was used; the spray solution was a 5% (w / w) sodium chloride solution with a pH of 6.5-7.2; the test chamber temperature was 35±2℃; and the salt spray deposition rate was 1.5 mL / 80 cm. 2 • h; Test procedure: Place the cured sealing layer sample in a salt spray test chamber and spray continuously for 72 hours. After the test, take out the sample, rinse the surface gently with clean water, and dry at room temperature for 2 hours. Observe whether there are corrosion spots, blistering, peeling and other phenomena on the sample surface, and test the deviation of the pressure bearing capacity from the initial value. The specific results are shown in Table 2.

[0039] Storage stability test: The refrigerant sample was sealed and placed in a constant temperature environment of 25℃. Samples were taken and observed after 30 days and 180 days to check for stratification. The initial viscosity and the final viscosity after 30 days and 180 days were measured using a rotational viscometer. The viscosity change rate was calculated as (final viscosity - initial viscosity) / initial viscosity × 100%, as detailed in Table 2. Due to the inability to form an effective sealing layer in Comparative Examples 1 and 3, some tests were not performed.

[0040] Table 1

[0041] As shown in Table 1, the refrigerants in Examples 1-5 exhibited excellent response speed and curing performance after leakage was triggered, with a response time of 4-6 seconds and a curing time of 17-22 minutes. The cured sealing layer achieved a Shore hardness of 42-44A and a pressure bearing capacity of 0.39-0.42 MPa, meeting the pressure shock protection requirements below 0.4 MPa. The refrigeration efficiency recovery rate after leak sealing was as high as 98.2-99.2%, indicating that the formation of the sealing layer had minimal impact on the operation of the refrigeration system.

[0042] Comparative Example 1 (without microcapsule coating) did not respond in the leak test, could not form a gel sealing layer, had a cooling efficiency recovery rate of only 63.2%, and a pressure resistance close to zero. This indicates that the unencapsulated peroxide had failed or was incompatible with the system during storage and could not trigger a reaction in the event of a leak.

[0043] Although Comparative Example 2 (without titanium catalyst) could respond, the response time was as long as 58 seconds and the curing time was 105 minutes, which far exceeded the range defined by this invention. The Shore hardness of the cured sealing layer was only 15A, the pressure bearing capacity was 0.12MPa, and the cooling efficiency recovery rate was 88.7%, all of which were significantly worse than those of the example. This indicates that the titanium catalyst plays a key role in rapidly initiating the polymerization reaction and forming a dense sealing layer.

[0044] Comparative Example 3 (without fluorinated acrylate) did not respond in the leak test, the refrigeration efficiency recovery rate was only 62.0%, and the pressure resistance was close to zero. This is directly related to the fact that the system separates into layers after preparation and cannot form a homogeneous system, proving that fluorinated acrylate oligomers are a necessary component to ensure the compatibility of additives with HFO bulk.

[0045] Table 2

[0046] As can be seen from the data in Table 2, the sealing layers of Examples 1-5 showed no significant deterioration after being treated at -45℃ for 72 hours and at 130℃ for 72 hours, with small hardness deviations. After 72 hours of neutral salt spray corrosion, there were no corrosion spots or blistering on the surface, and the pressure bearing capacity showed small deviations. This indicates that the sealing layer prepared by the present invention has excellent stability in a wide temperature range of -45℃ to 130℃ and in a humid salt spray environment.

[0047] After being sealed and stored at 25°C for 30 and 180 days, the systems in Examples 1-5 remained homogeneous and without stratification. The viscosity change rates after 30 and 180 days were both far below the qualified standard of 15%, indicating that the refrigerant prepared by this invention has excellent long-term storage stability.

[0048] Although Comparative Example 2 (without titanium catalyst) can form a sealing layer, it has poor environmental stability. After low-temperature treatment, it becomes embrittled and its hardness decreases by 7; after high-temperature treatment, it becomes sticky and its hardness increases by 13; after salt spray corrosion, it shows slight corrosion and its pressure bearing capacity decreases by 0.04 MPa. This further proves that the cross-linked network structure formed by the participation of titanium catalyst is crucial to the environmental stability of the sealing layer.

[0049] Comparative Example 1 (without microcapsule coating) showed precipitation after 30 days, with a viscosity change rate of 28.5%, and completely delaminated and failed after 180 days. This proves that the microcapsule coating technology is the key to achieving long-term storage stability by isolating and protecting peroxides.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A preparation process for an air-triggered HFO self-condensing refrigerant, wherein the refrigerant comprises HFO bulk and composite additives, the composite additives comprising a first additive and a second additive, the first additive being a fluorinated acrylate oligomer, and the second additive being composed of microencapsulated peroxide and an organotitanium chelate; the preparation process includes the following steps: (1) Polyvinylidene fluoride is dissolved in N,N-dimethylformamide to form an oil phase. Liquid paraffin and tert-butyl hydrogen peroxide aqueous solution are mixed to form a W / O type primary emulsion. The oil phase is added to the primary emulsion. After solvent evaporation and curing, and drying, microencapsulated peroxide is obtained. (2) Under nitrogen protection, the microencapsulated peroxide obtained in step (1) and the organotitanium chelate are mixed and compounded to prepare the second additive; (3) Add a composite additive consisting of the first additive and the second additive mentioned above to the HFO body, and mix them by high-speed shearing and stirring to obtain a refrigerant; The total mass of the composite additives accounts for 3 to 5.5% of the total mass of the HFO body.

2. The preparation process according to claim 1, characterized in that, In step (1), the mass ratio of polyvinylidene fluoride to N,N-dimethylformamide is 1:(4.3~4.8).

3. The preparation process according to claim 1, characterized in that, In step (1), the mass ratio of liquid paraffin to tert-butyl hydrogen peroxide aqueous solution is (5.73~6.8):

1.

4. The preparation process according to claim 1, characterized in that, The mass fraction of the tert-butyl hydrogen peroxide aqueous solution in step (1) is 60-80%.

5. The preparation process according to claim 1, characterized in that, The microencapsulated peroxide is prepared using polyvinylidene fluoride as the wall material, tert-butyl hydroperoxide as the core material, and a raw material system including sorbitan monooleate and liquid paraffin.

6. The preparation process according to claim 1, characterized in that, The organic titanium chelate mentioned in step (2) is tetrabutyl titanate.

7. The preparation process according to claim 1, characterized in that, The fluorinated acrylate oligomer mentioned in step (3) is a trifluoroethyl acrylate homopolymer with a molecular weight of 1000~3000.

8. The preparation process according to claim 1, characterized in that, The HFO body mentioned in step (3) is a mixture of R1234yf and R1234ze, with a mass ratio of R1234yf to R1234ze of (0.5~1):

1.

9. The preparation process according to claim 1, characterized in that, The first additive is added at a rate of 1.5-3% of the total mass of HFO, and the second additive contains microencapsulated peroxide at a rate of 1-1.5% of the total mass of HFO and organotitanium chelate at a rate of 0.5-1% of the total mass of HFO.

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