Explosion-proof membrane assembly and explosion-proof valve

Abstract

The invention provides an explosion-proof membrane assembly. The explosion-proof membrane assembly comprises an elastic membrane and a waterproof breathable membrane, the elastic film comprises a first surface, a second surface and a film body with the first surface and the second surface as boundaries, the thickness of the film body is 20-1000 microns, the pore area proportion of the first surface and / or the second surface is not larger than 5%, and the average pore diameter of the first surface and / or the second surface is not larger than 200 nm; the film forming material of the elastic film is selected from one of PDMS, latex, PU, EVA, POE, TPO, TPE or TPV; the unit pressure difference bulging height of the elastic film is not less than 3 * 10 <-7 > mm; the random vibration amplitude of the elastic film is not larger than 1 * 10 <-3 > mm. When the internal and external pressure difference reaches the bursting pressure, the bulging height of the elastic film is large, the elastic film has low strength, a large crevasse can be formed during bursting, so that pressure can be quickly released, and the random vibration amplitude of the elastic film is not larger than 1 * 10 <-3 > mm, so that the amplitude is small under the random vibration condition, and the elastic film can be quickly released. And the problem that the elastic film explodes in advance under normal working conditions is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of explosion-proof valves, and in particular to an explosion-proof membrane assembly and an explosion-proof valve. Background Art

[0002] The membrane assembly commonly used in explosion-proof valves usually has a waterproof and breathable membrane, which is generally a PTFE microporous membrane. The microporous structure in the PTFE microporous membrane meets the ventilation requirements during normal use, and when the air pressure reaches the preset limit value, the PTFE microporous membrane is punctured by a puncturing piece or other structure to achieve a pressure relief effect.

[0003] For example, in the Chinese utility model patent with the authorization announcement number CN218648096U, an explosion-proof valve is disclosed, wherein the explosion-proof valve includes a valve cover and a valve body that can be engaged with each other; a waterproof breathable membrane is arranged in the pressure relief channel of the valve body, and the waterproof breathable membrane is a PTFE microporous membrane; and a puncture piece with a sharp portion facing the waterproof breathable membrane is arranged on the valve cover. Due to the material characteristics of the PTFE microporous membrane, it has high hardness and poor toughness, and often has a relatively low elongation at break. Even if the internal and external pressure difference is large, only a small deformation can occur. Therefore, in order to ensure that the explosion-proof valve can burst and release pressure when the internal and external pressure difference of the explosion-proof valve reaches the designed bursting pressure, the distance between the waterproof breathable membrane and the puncture piece in the explosion-proof valve is only 0.8-1.2mm, so that the PTFE microporous membrane with a small deformation when the bursting pressure is reached can be punctured by the puncture piece to release pressure. If the distance between the two is too large, it is easy for the PTFE microporous membrane to fail to burst due to insufficient deformation under the bursting pressure, which leads to safety accidents.

[0004] In addition, the greater strength of the PTFE microporous membrane also makes it difficult to further expand the breach after it is punctured. Only a very small breach can be formed during the explosion. The explosion pressure relief capacity is relatively poor and cannot be quickly relieved. Therefore, if the explosion pressure relief capacity of the explosion-proof valve is to be improved, a PTFE microporous membrane with a smaller thickness and higher porosity can be tried to improve its deformation ability. This attempt can indeed make the PTFE microporous membrane form a larger deformation under the same pressure difference, so that it is easier to produce a large breach under the action of the puncture piece. However, since the explosion-proof valve is used in applications such as new energy vehicle battery packs, it has been in a vibrating working environment, and the spacing between the waterproof breathable membrane and the puncture piece is only 0.8-1.2mm, the PTFE microporous membrane with a smaller thickness and higher porosity is more deformed due to vibration, and it is easy to cause the PTFE microporous membrane to be punctured and damaged due to the deformation caused by vibration before the set burst pressure is reached, that is, the PTFE microporous membrane ruptures prematurely, resulting in a short service life of the explosion-proof valve.

[0005] Obviously, the single PTFE microporous membrane in the current explosion-proof valve is difficult to achieve rapid explosion and pressure relief under bursting pressure and avoid premature puncture of the puncture part due to excessive vibration amplitude under normal use conditions. Summary of the invention

[0006] In order to solve the problem that the PTFE microporous membrane cannot take into account the rapid explosion and pressure relief under the explosion pressure and avoid the premature puncture of the puncture member due to excessive vibration amplitude under normal use conditions when applied to the explosion-proof valve, the present invention provides an explosion-proof membrane assembly and an explosion-proof valve including the explosion-proof membrane assembly, and the specific scheme is as follows:

[0007] An explosion-proof membrane assembly, comprising an elastic membrane and a waterproof breathable membrane;

[0008] The elastic membrane comprises a first surface, a second surface and a membrane body bounded by the first surface and the second surface, the thickness of the membrane body is 20-1000 μm, the pore area of ​​the first surface and / or the second surface accounts for no more than 5%, and the average pore size of the first surface and / or the second surface is no more than 200 nm;

[0009] The film-forming material of the elastic film is selected from one of PDMS, latex, PU, ​​EVA, POE, TPO, TPE or TPV;

[0010] The unit pressure difference bulging height of the elastic membrane is not less than 3×10 -7 mm;

[0011] The random vibration amplitude of the elastic film is not greater than 1×10 -3 mm.

[0012] Optionally, the thickness of the membrane body is 20-500 μm, and the bulging height of the elastic membrane per unit pressure difference is not less than 1×10 -6 mm.

[0013] Optionally, the thickness of the membrane body is 20-200 μm, and the bulging height of the elastic membrane per unit pressure difference is not less than 1×10 -5 mm.

[0014] In applications such as new energy vehicle battery packs, explosion-proof valves (also explosion-proof membrane components, the same below) actually have multiple working states, one of which is that the battery pack does not have a thermal runaway problem. Therefore, although the temperature inside the battery pack rises due to charging and discharging, the heating rate is slow. At this time, the air permeability of the waterproof and breathable membrane is sufficient to balance the air pressure inside and outside the battery pack. Therefore, the pressure difference on both sides of the membrane component of the explosion-proof valve is small. In this working state, the main reason for the deformation of the elastic membrane is the vibration that is difficult to avoid during use. Another reason is that the battery pack has a thermal runaway problem, the temperature inside the battery pack rises rapidly, and the air permeability of the waterproof and breathable membrane is not enough to quickly balance the air pressure inside and outside the battery pack. Therefore, a large pressure difference is quickly generated on both sides of the membrane component of the explosion-proof valve. In this working state, the main reason for the deformation of the elastic membrane is the rapidly increasing pressure difference on both sides. Unlike the common application scenarios of general elastic membranes, which are often relatively constant working conditions, the special multi-working condition application scenarios in this application put forward special requirements on the elastic membrane. It requires that the elastic membrane can not only be able to deform rapidly and in large quantities under the action of the air pressure difference on both sides when thermal runaway occurs, but also ensure that it will not suffer undesirable premature damage due to the amplitude generated by vibration when thermal runaway does not occur.

[0015] Specifically, the explosion-proof membrane assembly provided by the present application includes an elastic membrane and a waterproof breathable membrane. The function of the waterproof breathable membrane is to prevent water from entering and balance the internal and external pressures under normal use conditions, so as to prevent excessive increase in the internal pressure of devices such as battery packs during normal operation; the elastic membrane in the explosion-proof membrane assembly is selected from one of PDMS, latex, PU, ​​EVA, POE, TPO, TPE or TPV, all of which have relatively good deformation ability and can produce relatively large deformation under pressure, and the bulging height per unit pressure difference is not less than 3×10 -7 mm, where the unit pressure difference bulge height refers to the bulge height of the elastic membrane per square millimeter area and per micron thickness under each kilopascal pressure difference. -7 mm, then after an elastic membrane with a thickness of 20-1000 μm is combined with a waterproof breathable membrane to form an explosion-proof membrane assembly, when the pressure difference rises rapidly, when the internal and external pressure difference reaches the bursting pressure, the bulging height of the elastic membrane is relatively large, and the bursting condition of the explosion-proof valve is quickly reached. In addition, the larger bulging height per unit pressure difference means that the elastic membrane used in the present application has a lower strength, and a large breach can be formed during the explosion, and the breach is also easier to further expand, thereby enabling rapid pressure relief to avoid safety accidents.

[0016] Moreover, since the random vibration amplitude of the elastic membrane is no more than 1×10 -3mm, then the amplitude of the elastic membrane with a thickness of 20-1000μm and a certain area under random vibration conditions is small, so the problem of premature explosion of the elastic membrane will not occur under normal working conditions. The above-mentioned random vibration amplitude refers to the amplitude of the elastic membrane per square millimeter area and per micron thickness under random vibration test conditions. Among them, the test method of random vibration amplitude is operated in accordance with the international standard ISO16750-3: the vibration frequency is 10~2000HZ, the frequency acceleration is 10(m / s 2 )2 / Hz, XYZ axis each test for 42 hours. Specifically, when testing the random vibration amplitude of the elastic membrane in the explosion-proof membrane assembly, the explosion-proof membrane assembly can be assembled in a test fixture or installed in an explosion-proof valve, and a sharp puncture piece is set at a certain distance. If the elastic membrane undergoes the random vibration test under the above conditions and does not show damage, it is considered that the amplitude of the elastic membrane has not reached the distance between it and the puncture piece.

[0017] In general, the explosion-proof membrane assembly provided by the present application and the elastic membrane in the membrane assembly solve the problem that the PTFE microporous membrane in the existing explosion-proof valve cannot take into account the rapid explosion and pressure relief under the explosion pressure and avoid premature puncture by the puncture member due to excessive vibration amplitude under normal use conditions. It solves the technical problem that the explosion-proof valve application field has always hoped to solve but has never succeeded.

[0018] It should be emphasized that the technical problem solved by applying the elastic membrane to explosion-proof applications of battery packs is unique. This technical problem does not exist in other existing technical fields, and there is no technical inspiration that can be applied in other existing technical fields. Therefore, this application itself is of pioneering significance. It not only solves the above technical problems, but also provides new solutions for the selection of explosion-proof membrane materials and performance optimization, that is, changing from a single membrane material to a combination of membrane materials of different materials. Membranes of different materials each play their role, thereby taking into account the different performance requirements under normal use conditions and under conditions of rapid pressure difference increase.

[0019] In addition, the hole area of ​​the first surface and / or the second surface of the elastic membrane accounts for no more than 5%, and the average pore size of the first surface and / or the second surface is no more than 200nm, that is, the surface of the elastic membrane is almost dense, isolating oxygen, and is more resistant to thermal oxygen aging. It has a long service life and stable performance, ensuring that the performance of the elastic membrane in all aspects is always stable within the service life of the explosion-proof valve, especially ensuring that its deformation under a certain pressure difference is relatively stable, and it can quickly explode and release pressure under the explosion pressure to ensure safety.

[0020] It is worth noting that the deformation of the elastic membrane caused by the pressure difference on both sides and the deformation of the elastic membrane caused by vibration have different deformation causes and deformation behaviors. For example, the deformation caused by the pressure difference on both sides is unilateral and continuously superimposed, while the deformation caused by vibration is continuously reciprocating and offsets each other or is superimposed. Therefore, based on the specific multi-working condition application scenarios of this application, when both performances are met, it can be ensured that the explosion-proof membrane assembly meets the use requirements under all working conditions.

[0021] In summary, the explosion-proof membrane assembly provided by the present application is composed of an elastic membrane and a waterproof breathable membrane. The waterproof breathable membrane meets the requirements of waterproof breathability and balancing the internal and external air pressure under normal use conditions. In this process, the elastic membrane with a small random vibration amplitude can ensure that there is no premature explosion due to vibration during use; and when the internal and external pressure difference rises rapidly, the elastic membrane forms a larger deformation under the pressure difference and quickly reaches the explosion condition, forming a large breach when it explodes, so that it can quickly release pressure. In addition, compared with the PTFE microporous membrane with higher strength, the elastic membrane with lower strength undergoes a larger deformation under the pressure difference on both sides, and with the increase of the deformation amount, the elastic membrane itself has the ability to burst and release pressure, so it is not necessary to use it with structures such as puncture pieces, and the PTFE microporous membrane that is difficult to burst itself relies more on structures such as puncture pieces to achieve the pressure relief effect. Therefore, the explosion-proof membrane assembly in the present application can be used alone and has the function of an explosion-proof valve, and of course it can also be combined into an explosion-proof valve and used in conjunction with puncture pieces.

[0022] It is understood that by comparing the scanning electron microscope images (SEM images) of the first outer surface and / or the second outer surface of the elastic membrane in the present application, for example, comparing the SEM images with a magnification of 10,000 times, and by manual measurement or automatic measurement by software (such as Image-J), the morphological parameters such as the pore size, pore area ratio, and pore distribution density of the two sides of the elastic membrane can be obtained; and the thickness of the elastic membrane can be measured by comparing its cross-sectional SEM images or directly using a thickness gauge. In addition, when comparing the SEM images of the elastic membrane, sometimes it is found that there are several disordered cracks on the first outer surface and the second outer surface. These disordered cracks may be caused by the electron beam bombarding the first outer surface and the second outer surface when the scanning electron microscope uses the electron beam to perform high-resolution image analysis on the sample. Of course, it may also be caused by the liquid nitrogen freezing brittle fracture sample preparation; therefore, the disordered cracks on the first outer surface and the second outer surface should not be considered as pore structures.

[0023] On the basis of the above, the thickness range of the elastic membrane can be selected as 20-500μm, and further selected as 20-200μm. The upper limit of the thickness of the elastic membrane is smaller, which means that when the pressure difference rises rapidly, the deformation under a certain pressure difference becomes larger, so it has a relatively larger bulging height per unit pressure difference, and can form a larger breach during explosion and release pressure faster; of course, at this time, it is still necessary to ensure that the elastic membrane is not damaged due to vibration.

[0024] Furthermore, the average pore size of the first surface and / or the second surface is not greater than 150 nm, and the pore density of the first surface and / or the second surface is not greater than 5 / μm. 2 .

[0025] In application scenarios such as battery packs, under working conditions such as outdoors in summer, the road surface temperature is high and the elastic membrane is at a relatively high temperature. At this time, it is preferred that the pore size on the surface of the elastic membrane is small, the pore density is low, the surface is almost dense, and it has better thermal oxygen aging performance, so that the performance of the elastic membrane remains stable within the service life of the explosion-proof membrane assembly.

[0026] Furthermore, the deformation coefficient of the elastic film is 4×10 2 ~3×10 4 um, and the deformation coefficient is the product of the A-type Shore hardness value of the elastic film and the thickness of the film body.

[0027] For the elastic membrane in the explosion-proof membrane assembly, its thickness value and its A-type Shore hardness value are not relatively independent parameters, and the two are often inseparable. This is because, as mentioned above, the elastic membrane needs to ensure its small amplitude under normal use conditions. Therefore, the smaller the thickness value of the elastic membrane and the smaller the A-type Shore hardness value, the higher its amplitude will be, making it difficult to ensure anti-vibration performance. If the thickness value of the elastic membrane is larger and the A-type Shore hardness value is larger, it will result in a smaller bulge height per unit pressure difference under the pressure difference on both sides, making it difficult to ensure the explosive pressure relief performance. For example, when the thickness of the elastic membrane is small and the A-type Shore hardness value is simultaneously small, its anti-vibration performance is weak, and vice versa, the explosive pressure relief capacity decreases. The inventors of the present application found that when the product of the two values ​​is 4×10 2 ~3×10 4 um, it means that even if the thickness of the elastic film is small, its slightly larger hardness makes it have good anti-vibration performance and avoids vibration failure; even if the thickness of the elastic film is large, its slightly smaller hardness makes it have sufficient explosion pressure relief performance. Therefore, the hardness and thickness of the elastic film are a set of control parameters that should not be divided, so that the explosion-proof membrane assembly has better performance both under normal use conditions and under abnormal conditions of thermal runaway.

[0028] Furthermore, the deformation response hysteresis of the elastic film is not greater than 20%.

[0029] As mentioned above, under the action of the waterproof breathable membrane, the air pressure difference on both sides of the elastic membrane changes slowly under normal use conditions, while under abnormal conditions of thermal runaway, the air pressure difference on both sides of the elastic membrane changes rapidly. Due to the different speeds of change of the air pressure difference, the deformation behavior of the elastic membrane is also different. For example, under normal use conditions, the air pressure difference is relatively small, and the elastic membrane has sufficient time to deform, so its deformation performance is not challenged. Under abnormal conditions, the rapidly changing air pressure difference requires the elastic membrane to deform accordingly in a shorter period of time, thereby ensuring that the elastic membrane can produce a bursting pressure relief effect in a shorter response time when the designed bursting pressure is reached. This can ensure that the explosion-proof membrane assembly responds quickly to explosion under thermal runaway conditions to ensure the safety of the equipment under abnormal conditions.

[0030] The deformation response hysteresis rate of the elastic membrane is |P2 / P1-100%|, where P1 is the bursting pressure at a pressurization speed of 2kPa / s, and P2 is the bursting pressure under rapid pressurization. Specifically, the test conditions of P1 are to make the explosion-proof membrane assembly into an explosion-proof valve for testing (explosion-proof valve bursting pressure test), or to fix the elastic membrane to a test fixture for testing (elastic membrane bursting pressure test), connect the explosion-proof valve or the test fixture to the air source, and increase the pressure at a rate of about 2kPa / s until the elastic membrane bursts, and the bursting pressure at this time is recorded as P1. The test conditions of P2 are: make the explosion-proof membrane assembly into an explosion-proof valve for testing (explosion-proof valve bursting pressure test), or fix the elastic membrane to the test fixture for testing (elastic membrane bursting pressure test), preset the gas source pressure, then connect the explosion-proof valve or the test fixture to the gas source, compare whether a burst occurs, increase the preset pressure of the gas source with a gradient of 0.1kpa, repeat the above operation until the explosion-proof valve bursts, and record the preset pressure of the gas source at this time, which is P2.

[0031] Since the test condition of P2 is instantaneous pressurization, the time for the elastic membrane to fully deform is short. The ratio of P2 to P1 can directly show the difference in burst pressure between the elastic membrane under a lower pressurization speed and under instantaneous pressurization conditions. The smaller the difference between the two, the shorter the time it takes for the elastic membrane to deform in response to changes in air pressure difference, and the lower the correlation with the pressurization speed. Then, even if the thermal runaway state is the most severe deflagration state, and the pressure difference on both sides reaches the burst condition in an instant, the elastic membrane can still burst in a shorter response time, and can therefore adapt to more severe working conditions.

[0032] It should be noted that it is meaningless to discuss the absolute value of P2 alone. The deformation response hysteresis must be controlled to be no more than 20% to ensure that the elastic membrane has not only a "short response time" but also a "sufficient response" under instantaneous pressure conditions. This is because the elastic membrane has a value of no less than 3×10 -7The unit pressure difference bulging height of mm can already indicate that the elastic membrane can fully respond and deform under a smaller pressurization speed. The deformation response hysteresis rate is characterized by the ratio of P2 to P1, which means that the deformation response time must be based on the elastic membrane having fully responded. Therefore, a deformation response hysteresis rate of no more than 20% can actually characterize that the elastic membrane has not only a short response time but also a relatively sufficient response and deformation under the condition of instantaneous pressurization.

[0033] Furthermore, the elastic film has a cross-linking density of no more than 6×10 -4 mol / ml of PDMS, and the degree of polymerization of the PDMS is not greater than 500.

[0034] In the present application, the elastic membrane is preferably made of PDMS material, and unlike the general perception that the PDMS elastic membrane is expected to have a higher cross-linking density / polymerization degree to resist thermal oxidative aging under high temperature conditions such as outdoors in summer, to ensure that the elastic membrane has less performance degradation over a longer service life, the PDMS elastic membrane is specifically controlled to have a slightly lower cross-linking density / polymerization degree, which in turn enables it to have better resistance to thermal oxidative aging, which is a very unexpected result.

[0035] Specifically, for common applications of explosion-proof valves such as battery packs, firstly, the battery pack's own charging and discharging process will generate heat. Although the heating process is generally slow, the absolute value of the temperature is relatively high. Secondly, the ambient temperature in summer may reach above 40°C, and the outdoor road temperature may even reach above 60°C. The heat generated during the working process of the battery pack and the high temperature conditions of the environment will cause the temperature of the battery pack to rise very high, even to above 70°C. Moreover, the design service life of explosion-proof valves used in automotive battery packs is generally relatively long, even up to more than 15 years. The harsh use environment and high service life requirements pose a high challenge to the elastic membrane's resistance to thermal oxidation aging.

[0036] It is particularly important to note that for the currently common single PTFE membrane explosion-proof valve, the material properties of PTFE make it extremely temperature resistant (above 200°C) and stable, so it does not have the above problems. For the common application scenarios of PDMS elastic membranes, such as microchips, biological models, 3D printing, packaging, microfluidics, etc., either it does not have the problem of high-temperature thermal oxidation aging, or it can be replaced more easily, and there is no demand for a service life of more than 10 years in harsh environments.

[0037] Therefore, in order to avoid the degradation of the mechanical properties of the elastic membrane caused by thermal oxidative aging, the general practice is to increase the initial cross-linking density and initial polymerization degree of the elastic membrane as much as possible, so that the elastic membrane has higher stability. For the conventional application scenarios of PDMS mentioned above (the application environment is relatively mild and the degree of thermal oxidative aging is relatively weak), this method is very effective and can effectively delay the occurrence of thermal oxidative aging, thereby making it have more stable mechanical properties.

[0038] However, the PDMS elastic membrane in this application is used in special high-temperature and long-life scenarios. Although increasing the initial crosslinking density and initial polymerization degree of the elastic membrane material can also delay the occurrence of thermal oxidative aging, the inventors of this application unexpectedly discovered that appropriately reducing the initial crosslinking density and initial polymerization degree of the elastic membrane can make the elastic membrane have more stable mechanical properties. This may be because, as a silicone rubber, the PDMS elastic membrane will add a crosslinking agent during its production process to promote monomer crosslinking and inevitably remain in the PDMS. The crosslinking behavior is very slow under mild conditions, but as the temperature increases, the crosslinking speed increases accordingly.

[0039] This means that for the high-temperature and harsh working conditions in this application, if the initial cross-linking density and initial degree of polymerization of the PDMS elastic membrane are both high, although the rate of thermal oxidative aging is reduced, the occurrence of thermal oxidative aging is inevitable; in addition, due to the high cross-linking density, even under high temperature conditions, it is difficult to further cross-link the PDMS elastic membrane. Therefore, the PDMS elastic membrane only undergoes a very small amount of cross-linking behavior and a relatively large amount of thermal oxidative aging behavior in a high-temperature environment, which manifests as a slow deterioration of the mechanical properties of the PDMS elastic membrane.

[0040] In contrast, in this application, the initial cross-linking density of the PDMS elastic membrane is controlled to be no greater than 6×10 -4 mol / ml and the initial degree of polymerization is not greater than 500, which indicates that the PDMS elastic film still has the possibility of further cross-linking reaction as the ambient temperature increases. Although the thermal oxidative aging rate in the present application is relatively high, the PDMS elastic film will further undergo cross-linking behavior under high temperature conditions. Therefore, the PDMS elastic film in the present application will undergo a slightly larger amount of cross-linking behavior and a slightly larger amount of thermal oxidative aging behavior in a high temperature environment, wherein the cross-linking behavior will lead to an increase in the cross-linking density, thereby making the PDMS elastic film have higher mechanical properties, while the thermal oxidative aging behavior often leads to the breakage of molecular chain segments, etc., thereby deteriorating the mechanical properties of the PDMS elastic film. Therefore, the effects of the cross-linking behavior and the thermal oxidative aging behavior on the mechanical properties offset and compensate each other, which can make the PDMS elastic film have higher mechanical property stability.

[0041] In summary, in the membrane assembly provided by the present application, the membrane material of the elastic membrane is preferably PDMS, and by reasonably controlling the cross-linking density and polymerization degree of PDMS, the PDMS has a relatively low initial cross-linking density and initial polymerization degree, the purpose of which is to ensure that the elastic membrane has a relatively good initial deformation ability, and the deformation produced under a certain pressure difference is large, and because PDMS can be compensated by cross-linking behavior under high temperature conditions even if thermal oxidative aging occurs during high temperature and long-term working, the elastic membrane always has a relatively good deformation ability. Selecting PDMS as the membrane material of the elastic membrane and controlling its cross-linking density at a relatively low level can ensure the good initial deformation ability of the elastic membrane, and will not cause excessive deterioration of the deformation ability due to thermal oxidative aging during use, but can maintain a relatively stable level, so that it can always form a large deformation under pressure, and can form a large breach when it explodes.

[0042] Based on this, the elastic membrane of the present application is preferably PDMS, and by reasonably controlling the initial cross-linking density and polymerization degree of PDMS constituting the elastic membrane, the value of the former is not greater than 6×10 -4 mol / ml, and the latter value is not greater than 500. On the one hand, the elastic film has a relatively good initial deformation ability, and on the other hand, the elastic film has a long-term stability of mechanical properties under the specific high temperature and harsh working conditions of this application.

[0043] The selection of this specific membrane material and the reasonable control of the cross-linking density and degree of polymerization have overcome technical prejudice to a certain extent, because it is generally believed that the cross-linking density and degree of polymerization of the membrane material should be increased as much as possible to reduce the increase in the two during use, so as to maintain a relatively stable deformation capacity and ensure stable blasting.

[0044] Furthermore, the cross-linking density of the PDMS is not less than 4×10 -4 mol / ml, and the degree of polymerization of the PDMS is not less than 50.

[0045] Control the cross-linking density and polymerization degree of PDMS, the former should be no less than 4×10 -4 mol / ml, and the latter is not less than 50. The purpose is to avoid too low initial cross-linking density of PDMS. If the initial polymerization degree is too low, on the one hand, the membrane material is too soft, and the vibration amplitude under normal use conditions may be too large, which is easy to be punctured in advance. Moreover, if the initial cross-linking density of PDMS is less than 4×10 -4mol / ml, and the initial degree of polymerization is lower than 50, then, under high temperature conditions, cross-linking behavior may dominate and thermal-oxidative aging behavior may account for a lower proportion, resulting in a larger extent of further cross-linking during the use of the explosion-proof valve, and the cross-linking density will be greatly increased, while the probability of main chain breakage will be relatively low. Correspondingly, the deformation capacity of the elastic film will also be greatly reduced, that is, the elastic film cannot maintain a relatively stable deformation capacity, the elastic film may become very hard, and no large breach can be formed during the explosion.

[0046] It should be noted that, as mentioned above, for the specific working conditions of this application, degradation of the mechanical properties of the elastic membrane is certainly undesirable, but improvement of the mechanical properties of the elastic membrane is also undesirable, and instead the stability of the mechanical properties of the elastic membrane needs to be maintained.

[0047] Furthermore, before and after the heat and moisture treatment, the change rate of the crosslinking density of the elastic film does not exceed 12%, wherein the heat and moisture treatment refers to storing the elastic film at a temperature of 85° C. and a humidity of 85% for 96 hours.

[0048] Furthermore, before and after the heat and moisture treatment, the change rate of the crosslinking density of the elastic film does not exceed 10%, wherein the heat and moisture treatment refers to storing the elastic film at a temperature of 85° C. and a humidity of 85% for 96 hours.

[0049] Furthermore, before and after the heat and moisture treatment, the change rate of the crosslinking density of the elastic film does not exceed 8%, wherein the heat and moisture treatment refers to storing the elastic film at a temperature of 85° C. and a humidity of 85% for 96 hours.

[0050] Furthermore, before and after the heat and moisture treatment, the change rate of the unit pressure difference bulging height of the elastic membrane does not exceed 15%, and after the heat and moisture treatment, the random vibration amplitude of the elastic membrane is not greater than 1×10 -3 mm; wherein the heat and humidity treatment refers to storing the elastic film at a temperature of 85°C and a humidity of 85% for 96 hours.

[0051] Furthermore, before and after the high-temperature treatment, the change rate of the unit pressure difference bulging height of the elastic membrane does not exceed 20%, wherein the high-temperature treatment refers to storing the elastic membrane at a temperature of 125° C. for 96 hours.

[0052] After extreme heat and humidity treatment (temperature of 85°C, humidity of 85%), the crosslinking density of the elastic film did not change by more than 12%, indicating that under more severe high temperature and high humidity conditions, the crosslinking density of the elastic film and the bulge height per unit pressure difference only changed slightly, so the stability of its mechanical properties was relatively high. After high temperature treatment at 125°C, the change rate of the bulge height per unit pressure difference did not exceed 20%, indicating that the elastic film made of PDMS can still maintain a basically stable deformation capacity after extreme heat and humidity treatment and high temperature treatment, so that during the use of the explosion-proof valve, the elastic film can stably burst under the bursting pressure.

[0053] Furthermore, the present application discloses an explosion-proof valve, comprising a valve body and a valve cover, wherein the valve body is provided with the explosion-proof membrane assembly as described above.

[0054] Furthermore, the inner surface of the valve cover has a puncturing member.

[0055] The present application provides an explosion-proof valve with the membrane assembly. Since the membrane assembly includes an elastic membrane and a waterproof and breathable membrane, the waterproof and breathable membrane can conventionally be selected from a PTFE microporous membrane. Under normal use conditions of the explosion-proof valve, the waterproof and breathable membrane plays a role in waterproofing and balancing the internal and external air pressures. Moreover, under normal use conditions, the random vibration amplitude of the elastic membrane will not reach the bursting height of the explosion-proof valve, and thus it will not be punctured or exploded prematurely, ensuring that under normal use conditions, the explosion-proof valve can work stably and exert its waterproof and breathable functions. When the internal and external pressure difference of the explosion-proof valve rises rapidly, the elastic membrane can form a greater deformation under the action of the pressure difference, and the bulging height reaches the bursting height, forming a large breach during the explosion, thereby enabling rapid pressure relief.

[0056] Among them, the valve cover can be connected to one end of the valve body by a snap connection or a thread, and the valve body can be installed at the vent of the equipment by thread; or, the valve body and the valve cover are formed as one piece by injection molding, and the valve body is installed at the vent of the equipment by thread; or, the valve body is installed at the vent of the equipment by thread, and the valve cover is arranged around and above the valve body and fixed to the equipment.

[0057] Of course, as mentioned above, the explosion-proof membrane assembly in the present application can be assembled into an explosion-proof valve and installed on a device (such as a battery pack) for use in conjunction with the piercing member in the explosion-proof valve, or the explosion-proof membrane assembly can be directly integrated (such as by bonding, welding, etc.) into the device for use.

[0058] Beneficial effects of the present application: The explosion-proof membrane assembly provided by the present application includes an elastic membrane and a waterproof breathable membrane. The waterproof breathable membrane is used to prevent water from entering the membrane under normal use conditions and balance the internal and external pressures to prevent excessive internal pressure increases in devices such as battery packs during normal operation. The elastic membrane in the explosion-proof membrane assembly is selected from one of PDMS, latex, PU, ​​EVA, POE, TPO, TPE or TPV, all of which have relatively good deformation ability and can produce relatively large deformation under pressure. The unit pressure difference bulging height is not less than 3×10 -7 mm, because the unit pressure difference bulge height is not less than 3×10 -7 mm, then after the elastic membrane with a thickness of 20-1000 μm is combined with the waterproof breathable membrane to form a membrane assembly, when the pressure difference rises rapidly, when the internal and external pressure difference reaches the bursting pressure, the bulging height of the elastic membrane is relatively large, and the bursting condition of the explosion-proof valve is quickly reached. Moreover, the larger unit pressure difference bulging height means that the elastic membrane used in this application has a lower strength, and a large rupture can be formed during the blasting, and the rupture is also easier to further expand, so that the pressure can be quickly released to avoid safety accidents. Moreover, since the random vibration amplitude of the elastic membrane is not greater than 1×10 -3 mm, then the elastic membrane with a thickness of 20-1000μm and a certain area has a small amplitude under random vibration conditions, so the problem of premature rupture of the elastic membrane will not occur under normal working conditions.

[0059] The present application transfers the elastic membrane to the battery pack, solving the problem that the PTFE microporous membrane in the existing explosion-proof valve cannot take into account rapid explosion and pressure relief under explosion pressure and avoid premature puncture by the puncture member due to excessive vibration amplitude under normal use conditions. The transfer itself is of pioneering significance. It not only solves the above technical problems, but also provides a new solution for the selection of explosion-proof membrane materials and performance optimization, that is, changing from a single membrane material to a combination of membrane materials of different materials. The membrane materials of different materials each play their role, thereby taking into account the different performance requirements under normal use conditions and under the condition of rapid increase in pressure difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 Schematic diagram of the structure of the explosion-proof membrane assembly provided in the embodiment of the present invention Figure 1 ;

[0061] Figure 2 Schematic diagram of the structure of the explosion-proof membrane assembly provided in the embodiment of the present invention Figure 2 ;

[0062] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure of the elastic membrane;

[0063] Figure 4This is a scanning electron microscope image of the first surface of the PDMS elastic membrane provided in Example 3 of the present invention, and the magnification in the image is 10K×;

[0064] Figure 5 This is a scanning electron microscope image of the second surface of the PDMS elastic membrane provided in Example 3 of the present invention, and the magnification in the image is 10K×;

[0065] Figure 6 A cross-sectional view of an explosion-proof valve (including an explosion-proof membrane assembly) provided in an embodiment of the present invention;

[0066] Among them, 10 is an explosion-proof membrane assembly, 11 is an elastic membrane, 12 is a waterproof and breathable membrane, 13 is a double-sided adhesive tape, 20 is a valve body, 21 is a valve cover, and 22 is a puncture piece. DETAILED DESCRIPTION

[0067] The explosion-proof membrane assembly and explosion-proof valve provided in this application are introduced in detail below.

[0068] like Figure 1-3 As shown, an explosion-proof membrane assembly 10 includes an elastic membrane 11 and a waterproof breathable membrane 12, wherein the waterproof breathable membrane 12 may be a PTFE microporous membrane; the elastic membrane 11 includes a first surface 111, a second surface 112, and a membrane body bounded by the first surface 111 and the second surface 112. The pore area of ​​the first surface 111 and / or the second surface 112 of the elastic membrane 11 accounts for no more than 5%, and the average pore size of the first surface 111 and / or the second surface 112 is no more than 200 nm, that is, the pore area of ​​at least one of the first surface 111 and the second surface 112 is no more than 5%, and the average pore size of at least one of the first surface 111 and the second surface 112 is no more than 200 nm.

[0069] The film-forming material of the elastic film 11 is selected from one of PDMS, latex, PU, ​​EVA, POE, TPO, TPE or TPV. Among them, PDMS refers to polydimethylsiloxane, PU refers to polyurethane, EVA refers to ethylene vinyl acetate copolymer, POE refers to polyethylene octene copolymer, TPO refers to polyolefin thermoplastic elastomer, TPE refers to thermoplastic elastomer material, and TPV refers to thermoplastic vulcanized rubber.

[0070] The explosion-proof membrane assembly 10 provided in the present application includes an elastic membrane 11 and a waterproof and breathable membrane 12. The elastic membrane 11 and the waterproof and breathable membrane 12 are provided in a split type and are respectively sealed, pasted or welded to two vents of the battery pack. Figure 1 Moreover, the distance between the elastic membrane 11 and the waterproof breathable membrane 12 provided in a split manner can be very close or very far.

[0071] Or, if Figure 2As shown, the effective area of ​​the waterproof breathable membrane 12 is located at the periphery of the elastic membrane 11, the elastic membrane 11 is circular, the waterproof breathable membrane 12 is annular, and the waterproof breathable membrane 12 is bonded to the outer side of the elastic membrane 11 through an annular double-sided adhesive 13, and the two are integrated. The explosion-proof membrane assembly 10 can be used alone, directly welded or bonded to the vent of the battery pack, or assembled in the explosion-proof valve housing, and the explosion-proof valve is installed at the vent of the battery pack.

[0072] For example, Figure 6 As shown, the present application also provides an explosion-proof valve, including a valve body 20 and a valve cover 21 connected to one end thereof, a piercing member 22 is arranged in the valve cover 21, and the aforementioned explosion-proof membrane assembly 10 is installed in the valve body 20. Specifically, the valve cover 21 is connected to one end of the valve body 20 by snap-fit ​​connection or threaded connection, and the explosion-proof membrane assembly 10 is fixed in the valve body 20 by welding or bonding.

[0073] Example 1

[0074] The explosion-proof membrane assembly 10 includes an elastic membrane 11 and a waterproof breathable membrane 12. The waterproof breathable membrane 12 is arranged around the outer periphery of the elastic membrane 11. The elastic membrane 11 is circular. To facilitate relevant tests, the size of the explosion-proof membrane assembly 10 is set to a diameter of 25 mm in the effective area of ​​the elastic membrane 11, and the waterproof breathable membrane 12 is annular, with an inner diameter of 30 mm and an outer diameter of 36 mm in the effective working area. The elastic membrane 11 is made of PDMS. In this embodiment, the cross-linking density of the PDMS elastic membrane 11 is controlled to be about 4.8×10 -4 mol / ml, the degree of polymerization is 129, the thickness is controlled to be about 20 μm, and the unit pressure difference bulging height is 846.5×10 -6 mm, and its random vibration amplitude is 0.87×10 -3 mm, its hardness is 29HA (Shore A), so its deformation coefficient is 5.8×10 2 μm.

[0075] In this embodiment, the explosion-proof membrane assembly 10 is installed in Figure 6 The valve body 20 of the explosion-proof valve shown forms an integrated explosion-proof valve, wherein a piercing member 22 is fixed to the inner surface of the valve cover 21, and the distance between the piercing member 22 and the elastic membrane 11 is 20 mm, and further performance testing is carried out.

[0076] Embodiment 2-7

[0077] The main difference between Example 2-7 and Example 1 is that, on the basis of keeping the PDMS material unchanged, the thickness of the PDMS elastic film 11, the bulging height per unit pressure difference and the random vibration amplitude are adjusted, as shown in Table 1 for details.

[0078] Example 8

[0079] The only difference between Example 8 and Example 1 is that there is no puncturing member on the inner surface of the valve cover 21. It should be noted that the height of the valve body 20 should be high enough to provide enough space for the elastic membrane 11 to fully swell. In addition, various performance tests were also performed.

[0080] Of course, in Example 8, the valve body 20 and the valve cover 21 can also be an integral injection-molded structure, and when in use, the valve body 20 is connected to the vent of the device by threads. Alternatively, the valve body 20 and the valve cover 21 are provided in a split type, the valve body 20 is connected to the vent of the device by threads, and the valve cover 21 is covered on the periphery and the top of the valve body 20 and fixed to the device.

[0081] Example 9

[0082] The only difference between Example 9 and Example 2 is that the explosion-proof membrane assembly 10 is not installed as an explosion-proof valve structure, but various performance tests are performed on the explosion-proof membrane assembly 10.

[0083] In actual use, the explosion-proof membrane assembly 10 in Example 9 is directly welded or bonded to the vent of the device. In addition, in order to prevent the explosion-proof membrane assembly 10 from being punctured by misoperation, an outer cover can be added outside the explosion-proof membrane assembly 10 to protect the explosion-proof membrane assembly 10.

[0084] It should be noted that, since the elastic membranes 11 used in Example 8 and Example 1 are completely the same, and the elastic membranes used in Example 9 and Example 2 are completely the same, the tests related to the elastic membrane 11 are not repeated.

[0085] Example 10

[0086] The main difference between Example 10 and Example 3 is that the elastic membrane 11 is not made of PDMS material, but a latex membrane of the same thickness is selected. The membrane selection parameters are detailed in Table 1.

[0087] Embodiment 11

[0088] The main difference between Example 11 and Example 3 is that the elastic membrane 11 is not made of PDMS material, but a PU membrane of the same thickness is selected. The membrane selection parameters are detailed in Table 1.

[0089] Example 12

[0090] The main difference between Example 12 and Example 6 is that, on the basis of maintaining the elastic membrane 11 as PDMS material and keeping the thickness unchanged, the cross-linking density and polymerization degree of the PDMS material are adjusted to be slightly higher, so that its characteristics such as the bulging height per unit pressure difference are changed. The membrane selection parameters are detailed in Table 1.

[0091] Embodiment 13

[0092] The main difference between Example 13 and Example 7 is that, on the basis of maintaining the elastic membrane 11 as PDMS material and keeping the thickness unchanged, the cross-linking density and polymerization degree of the PDMS material are adjusted to be slightly higher, so that its characteristics such as the bulging height per unit pressure difference are changed. The membrane selection parameters are detailed in Table 1.

[0093] Embodiment 14

[0094] The main difference between Example 14 and Example 1 is that, on the basis of maintaining the elastic membrane 11 as PDMS material and keeping the thickness unchanged, the cross-linking density and polymerization degree of the PDMS material are adjusted to be slightly lower, so that its characteristics such as the bulging height per unit pressure difference are changed. The membrane selection parameters are detailed in Table 1.

[0095] Embodiment 15

[0096] The main difference between Example 15 and Example 7 is that, on the basis of maintaining the elastic membrane 11 as PDMS material and keeping the thickness unchanged, the cross-linking density and polymerization degree of the PDMS material are adjusted to be slightly higher, so that its characteristics such as the bulging height per unit pressure difference are changed. The membrane selection parameters are detailed in Table 1.

[0097] Examples 16-19

[0098] The main difference between Examples 16-19 and Example 3 is that, on the basis of keeping the elastic membrane 11 as PDMS material and keeping the thickness unchanged, the cross-linking density and polymerization degree of the PDMS material are adjusted to be higher or lower, so that its characteristics such as the unit pressure difference bulge height are changed, and the various membrane selection parameters are detailed in Table 1. Specifically, the PDMS material in Example 16 has a relatively high cross-linking density, the PDMS material in Example 17 has a relatively high polymerization degree, the PDMS material in Example 18 has a relatively low cross-linking density, and the PDMS material in Example 19 has a relatively low polymerization degree.

[0099] Comparative Example

[0100] Comparative Example 1

[0101] The main difference between Comparative Example 1 and Example 1 is that, on the basis of maintaining the elastic membrane 11 as PDMS material, the elastic membrane 11 is adjusted to have an excessively low thickness of only 16 μm, and its cross-linking density and degree of polymerization are adjusted to be too low, so that it has a larger unit pressure difference bulging height and an excessively large random vibration amplitude. The various membrane selection parameters are detailed in Table 1.

[0102] Comparative Example 2

[0103] The main difference between Comparative Example 2 and Example 7 is that, on the basis of maintaining the elastic membrane 11 as PDMS material, the elastic membrane 11 is adjusted to have an excessively large thickness, reaching 1100 μm, and its cross-linking density and degree of polymerization are adjusted to be too high, so that it has an excessively small unit pressure difference bulging height. The various membrane selection parameters are detailed in Table 1.

[0104] Comparative Example 3

[0105] Comparative Example 3 is a single PTFE membrane solution. Specifically, on the basis of maintaining the overall radial dimensions unchanged, the explosion-proof membrane assembly 10 in Example 1 is replaced with a single PTFE membrane, and the diameter of the PTFE breathable membrane is the same as the outer diameter of the waterproof breathable membrane in Example 1, and the membrane selection is also the same. In order to ensure that the explosion-proof valve can be exploded smoothly, the knife-membrane spacing of the explosion-proof valve is set to 1 mm.

[0106] Comparative Example 4

[0107] On the basis of Comparative Example 3, in order to ensure good pressure relief capability of the explosion-proof valve after explosion, this comparative example replaces the PTFE membrane in Comparative Example 3 with a PTFE membrane with higher porosity. Specifically, the air permeability per unit area of ​​the PTFE membrane in this comparative example is 2.2 times that of the PTFE membrane in Comparative Example 3, and the knife-membrane spacing of the explosion-proof valve is set to 1.2 mm.

[0108] Table 1 Selection of elastic membranes in various embodiments and comparative examples

[0109]

[0110]

[0111] The elastic films in Examples 1-9, Examples 12-19 and Comparative Examples 1-2 are made of PDMS, and the elastic films in Examples 10 and 11 are made of latex and PU, respectively.

[0112] Performance Testing

[0113] 1. Vibration test

[0114] 1.1 Elastic membrane random vibration amplitude test

[0115] The random vibration amplitude of the elastic film 11 refers to the amplitude of the elastic film 11 per square millimeter area and per micron thickness under random vibration conditions, specifically in accordance with the international standard ISO16750-3 operation: the vibration frequency is 10 to 2000 Hz, the frequency acceleration is 10 (m / s 2)2 / Hz, and the XYZ axes are tested for 2 hours each. Specifically, when testing the random vibration amplitude of the elastic membrane in the explosion-proof membrane assembly, take the explosion-proof valve equipped with the explosion-proof membrane assembly in each embodiment, install it on the vibration fixture plate with a torque of 10±0.2N*m, and perform a random vibration test according to the above standards. During the test, first uniformly adjust the spacing between the elastic membrane 11 and the piercing member 22 to 5mm. If it can pass the random vibration test, it is considered that the actual vibration amplitude of the elastic membrane is less than 5mm, and there is no risk of vibration damage, and the spacing is no longer further reduced for testing; if it fails the random vibration test with a spacing of 5mm, the spacing is increased by 0.5mm each time for further random vibration testing until it can pass the random vibration test to determine its actual vibration amplitude (for example, if it fails at a spacing of 8.5mm, but passes at a spacing of 9mm, it is considered that its actual amplitude is 8.5mm).

[0116] It is particularly noted that since Examples 8-9 were not assembled into an explosion-proof valve structure, this test was not performed. The test conditions for Comparative Examples 1-2 were the same as above, and Comparative Examples 3-4 were also not performed this test.

[0117] 1.2 Explosion-proof valve vibration tolerance

[0118] The explosion-proof valves of each embodiment and comparative example (except embodiment 8-9) equipped with the above explosion-proof membrane assembly were installed on the vibration fixture plate with a torque of 10±0.2N*m, and then the fixture plate was fixed on the vibration test table, and the sinusoidal vibration parameters were set to 100-440Hz, 60m / s 2 , XYZ axis test 42h each, random vibration parameters 10~2000Hz, 10(m / s 2 )2 / Hz, XYZ axis each test 42h, start the equipment to test. Finally, the sample and the fixture plate after the vibration test were sealed with 3M glue and placed in a water tank with a depth of 1 meter and soaked for 30 minutes. After that, they were taken out and the 3M glue was torn off for observation. It was found that there was no water in the internal cavity and on the surface, indicating that the explosion-proof membrane assembly 10 provided in this embodiment would not be punctured by the puncture member under the normal vibration condition of the explosion-proof valve.

[0119] In particular, for the embodiment that passed the random vibration test with a spacing of 5 mm in the test 1.2, it is considered that there is no risk of vibration damage, so this test is no longer performed. According to the test results, both comparative examples 1 and 4 failed to pass this test, so it is considered that it is difficult to ensure good anti-vibration damage performance.

[0120] 2. Unit pressure difference bulge height

[0121] The bulging height per unit pressure difference of the elastic membrane 11 refers to the bulging height of the elastic membrane per square millimeter area and per micron thickness under each kilopascal pressure difference. When actually measuring the bulging height per unit pressure difference of the elastic membrane 11, for example, the elastic membrane 11 in each embodiment is installed on a test fixture connected to an air source, and the pressure is increased from 0 at a speed of about 0.5 kPa / s to ensure that the elastic membrane 11 has sufficient deformation time, and the corresponding bulging height data of the elastic membrane 11 when the pressure difference rises by 1 kPa is recorded in real time, and the corresponding bulging height of the elastic membrane 11 under the bursting pressure is recorded, and then the bulging height per unit pressure difference is further calculated.

[0122] 3. Explosion Pressure Relief Performance

[0123] The explosion-proof valves installed with the above-mentioned explosion-proof membrane assembly in each embodiment and comparative example are connected to the air source, and the air source pressure is increased at a rate of 1 kPa / s until an explosion occurs; then, the explosion-proof valve after the explosion is used as a test sample, and the air source pressure is preset to 0.5 kPa. Subsequently, the explosion-proof valve is connected to the air source, and the amount of gas passing through the explosion-proof valve within a certain period of time is measured, and the air permeability of the explosion-proof valve after the elastic membrane 11 bursts is calculated accordingly, and the unit is L / min@0.5 kPa.

[0124] 4. Type A Shore Hardness

[0125] The test of the A-type Shore hardness of the elastic film 11 is performed in accordance with GB / T531.1-2008. Since the thickness of a single elastic film 11 may not meet the minimum thickness requirement of the standard, multiple elastic films 11 may be stacked and tested.

[0126] 5. Cross-linking density and degree of polymerization of PDMS

[0127] 5.1 Crosslink density

[0128] (1) Experimental instruments

[0129] Newmai Analytical Instrument Co., Ltd., VTMR20-010V-I (test sample cross-linking density), resonance frequency 22.00MHz, magnet temperature controlled at 35.00±0.01℃, probe coil diameter 10mm.

[0130] (2) Experimental methods

[0131] The crosslink density of the rubber samples was tested at VTMR20-010V-I, 30°C.

[0132] (3) Test parameters

[0133] Cross-link density test parameters (CPMG_VD1 sequence): SF (MHz) = 22, O1 (Hz) = 100771.52, P1 (us) = 2.92, P2 = 5.68, SW (KHz) = 200, TW (ms) = 1500, RFD (ms) = 0.02, RG1 (db) = 10, DRG1 = 3, NS = 8, DR = 1, PRG = 3, Nech = 46; cross-link density fitting parameters: the inversion model is XLD-3.

[0134] 5.2 Degree of polymerization

[0135] The degree of polymerization is obtained by measuring the number average molecular weight of PDMS by gel permeation chromatography (GPC), and then dividing the number average molecular weight by the relative molecular weight of the monomer of PDMS. The method for measuring the number average molecular weight of PDMS is as follows: using a gel permeation chromatograph PL-GPC220, a model 2*PLgel 10um MIXED-B column, and a differential refractive index detector, first using an SP260 high-temperature sample dissolving device to heat and dissolve the sample and trichlorobenzene, and after dissolution, the injection volume is 200ul, and the test is carried out under the conditions of test temperature: 160°C, solvent flow rate: 1.0mL / min, solvent: TCB, trichlorobenzene, standard sample: PS, and then integrating and converting to calculate the number average molecular weight.

[0136] 6. Performance stability test

[0137] 6.1 Heat and humidity treatment

[0138] The elastic film 11 in each embodiment was stored at a temperature of 85° C. and a humidity of 85% for 96 hours, and the crosslinking density of the elastic film 11 before and after the heat and moisture treatment, the bulging height change before and after the heat and moisture treatment, and the random vibration amplitude were tested.

[0139] 6.2 High temperature treatment

[0140] The elastic membrane 11 in each embodiment was stored at a temperature of 125° C. for 96 hours, and the change rate of the bulging height per unit pressure difference of the elastic membrane 11 before and after the heat and moisture treatment was measured and calculated.

[0141] 7. Surface micromorphology

[0142] The first outer surface and / or the second outer surface of the elastic membrane is characterized by scanning electron microscopy (SEM), for example, by comparing SEM images at a magnification of 10,000 times, such as Figure 4 and 5 As shown, the morphological parameters such as pore size, pore area ratio, pore distribution density, etc. on the surfaces of both sides of the elastic membrane can be obtained by manual measurement or automatic measurement by software (such as Image-J).

[0143] 8. Deformation response hysteresis rate

[0144] The deformation response hysteresis rate of the elastic membrane is |P2 / P1-100%|, where P1 is the bursting pressure at a pressurization speed of 2kPa / s, and P2 is the bursting pressure under rapid pressurization. Specifically, the test conditions of P1 are to make the explosion-proof membrane assembly into an explosion-proof valve for testing (explosion-proof valve bursting pressure test), or to fix the elastic membrane to a test fixture for testing (elastic membrane bursting pressure test), connect the explosion-proof valve or the test fixture to the air source, and increase the pressure at a rate of about 2kPa / s until the elastic membrane bursts, and the bursting pressure at this time is recorded as P1. The test conditions of P2 are: make the explosion-proof membrane assembly into an explosion-proof valve for testing (explosion-proof valve bursting pressure test), or fix the elastic membrane to the test fixture for testing (elastic membrane bursting pressure test), preset the gas source pressure, then connect the explosion-proof valve or test fixture to the gas source, compare whether the explosion occurs, increase the preset pressure of the gas source with a gradient of 0.1kpa, repeat the above operation until the explosion-proof valve explodes, and record the preset pressure of the gas source at this time, which is P2. The test results are detailed in Table 2.

[0145] Table 2 Performance parameters

[0146]

[0147]

[0148] in conclusion

[0149] By comparing the technical solutions and test data of Examples 1-7, it is not difficult to find that when the elastic membrane and the waterproof breathable membrane are used together to form an explosion-proof membrane assembly, and its thickness, unit pressure difference bulging height and random vibration amplitude are controlled within a suitable range, the explosion-proof membrane assembly is installed as an explosion-proof valve and used in conjunction with the piercing member, so that the explosion-proof valve not only has good explosion pressure relief performance (can reach at least more than 60L / min@0.5kpa after explosion air permeability), but also has significantly good vibration tolerance performance. Specifically, when the thickness of the elastic membrane is not less than 100μm, its random vibration amplitude is already very small. Considering that a space must be set between the piercing member and the elastic membrane for the elastic membrane to deform, the possibility of vibration damage is already very low at this time. Therefore, the specific explosion-proof membrane assembly in this application has both good explosion pressure relief performance and anti-vibration damage performance. On this basis, as the thickness of the elastic membrane increases, the overall performance stability of the elastic membrane gradually improves, which may be due to the fact that thermal oxidation aging is more likely to occur on the surface, while the thermal cross-linking process is less related to the thickness of the elastic membrane.

[0150] On the basis of the foregoing, further comparing the technical solutions and various test data of Examples 1 and 8 and Examples 2 and 9, it is not difficult to find that the explosion-proof membrane assembly in the present application can not only be assembled into an explosion-proof valve for use with a puncture piece, but can also be used alone in the form of a membrane assembly. Of course, since Examples 8 and 9 are not used in conjunction with a puncture piece, it was found during the test that their bursting pressure is greater and the air permeability after the explosion is slightly lower. It can be selected as needed based on actual application conditions and cost considerations.

[0151] By comparing the technical solutions and various test data of Example 3 and Examples 10-11 as well as Comparative Examples 3-4, it is not difficult to find that elastic membranes of different materials, whether PDMS, latex, PU or other materials, can obtain significantly better comprehensive vibration resistance and explosion pressure relief performance than single PTFE components. However, at the same thickness, the performance stability of latex is worse than that of PDMS, and the explosion pressure relief performance of PU is worse than that of PDMS. Therefore, it is preferred to use an elastic membrane made of PDMS material with better comprehensive performance.

[0152] By comparing the technical solutions and test data of Examples 6 and 12 and Examples 5 and 13, if the thickness of the elastic membrane is large, it is not advisable to have too small a unit pressure difference bulging height, so as to avoid unnecessary loss of blasting pressure relief performance. Further comparing Example 1 and Example 14, when the thickness of the elastic membrane is small and the deformation coefficient is too small, although the explosion-proof membrane assembly has better blasting pressure relief performance, it is measured to have a large amplitude. In order to avoid damage caused by vibration, this solution is not a preferred solution; and comparing Example 7 and Example 15, when the thickness is large and the deformation coefficient is too large, its blasting pressure relief performance decreases, which is also not a preferred solution.

[0153] By comparing the technical solutions and test data of Example 3 and Examples 16-17, on the basis of the same thickness of the elastic film, whether the cross-linking density is too high or the degree of polymerization is too high, the stability of the elastic film performance will be significantly reduced, which is inconsistent with the general perception that increasing the cross-linking density and / or the degree of polymerization can improve the thermal oxidative aging resistance, and is a very unexpected result. Further comparing Example 3 and Examples 18-19, whether the cross-linking density is too low or the degree of polymerization is too low, the stability of the elastic film performance will also be significantly reduced, and although it can pass the vibration tolerance test, the necessary design redundancy must be considered. Therefore, both too high and too low cross-linking density and polymerization are not preferred in this application, which is different from the conventional method of improving the thermal oxidative aging resistance of the elastic film by increasing the cross-linking density and / or the degree of polymerization.

[0154] By comparing Example 1 with Comparative Example 1, if the thickness of the elastic membrane is too small, the unit pressure difference bulging height is too large, and the random vibration amplitude is too large, although the pressure relief performance after explosion is very excellent, the performance stability and anti-vibration damage performance of the elastic membrane are significantly reduced, which is inconsistent with the purpose of the present application. Further comparing Example 7 with Comparative Example 2, if the thickness of the elastic membrane is too large, the unit pressure difference bulging height is too small (when measuring the unit pressure difference bulging height of the elastic membrane in Comparative Example 2, because its bulging height under the corresponding pressure difference is too small, the calculated unit pressure difference bulging height value is much less than 3×10 -7 mm, no corresponding data was recorded. ) and the random vibration amplitude is too small. Although its anti-vibration performance is good, its explosion pressure relief performance is significantly reduced, which is also inconsistent with the purpose of this application. In fact, its response hysteresis rate has also increased significantly, which shows that it is difficult to ensure a short explosion response time under thermal runaway conditions where a rapid explosion is required.

[0155] Whether it is Comparative Example 3 or Comparative Example 4, when a single PTFE membrane is used as an explosion-proof membrane component, by adjusting the performance of the PTFE membrane, if the density of the PTFE membrane is high to ensure its anti-vibration damage performance, its explosion pressure relief performance will show a very significant decrease. If the density of the PTFE membrane is low, its anti-vibration damage performance is difficult to pass. Considering that it is very likely to have failed during thermal runaway conditions, it is difficult to achieve basic effects such as waterproofing and dustproofing in actual use, and therefore its explosion pressure relief performance is not further tested.

[0156] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An explosion-proof membrane assembly, comprising an elastic membrane and a waterproof breathable membrane; characterized in that: The elastic membrane comprises a first surface, a second surface and a membrane body bounded by the first surface and the second surface, the thickness of the membrane body is 20-1000 μm, the pore area of ​​the first surface and / or the second surface accounts for no more than 5%, and the average pore size of the first surface and / or the second surface is no more than 200 nm; The film-forming material of the elastic film is selected from one of PDMS, latex, PU, ​​EVA, POE, TPO, TPE or TPV; The unit pressure difference bulging height of the elastic membrane is not less than 3×10 -7 mm; The random vibration amplitude of the elastic film is not greater than 1×10 -3 mm.

2. The explosion-proof membrane assembly according to claim 1, characterized in that: The thickness of the membrane body is 20-500 μm, and the bulging height of the elastic membrane per unit pressure difference is not less than 1×10 -6 mm.

3. The explosion-proof membrane assembly according to claim 1, characterized in that: The thickness of the membrane body is 20-200 μm, and the bulging height of the elastic membrane per unit pressure difference is not less than 1×10 -5 mm.

4. The explosion-proof membrane assembly according to claim 1, characterized in that: The average pore size of the first surface and / or the second surface is not greater than 150 nm, and the pore density of the first surface and / or the second surface is not greater than 5 / μm 2 .

5. The explosion-proof membrane assembly according to claim 1, characterized in that: The deformation coefficient of the elastic film is 4×10 2 ~3×10 4 um, and the deformation coefficient is the product of the A-type Shore hardness value of the elastic film and the thickness of the film body.

6. The explosion-proof membrane assembly according to claim 1, characterized in that: The deformation response hysteresis rate of the elastic film is not greater than 20%.

7. The explosion-proof membrane assembly according to any one of claims 1 to 6, characterized in that: The elastic film has a cross-linking density of no more than 6×10 -4 mol / ml of PDMS, and the degree of polymerization of the PDMS is not greater than 500.

8. The explosion-proof membrane assembly according to claim 7, characterized in that: The cross-linking density of the PDMS is not less than 4×10 - 4 mol / ml, and the degree of polymerization of the PDMS is not less than 50.

9. The explosion-proof membrane assembly according to claim 7, characterized in that: Before and after the heat and moisture treatment, the crosslinking density change rate of the elastic film does not exceed 12%, wherein the heat and moisture treatment refers to storing the elastic film at a temperature of 85° C. and a humidity of 85% for 96 hours.

10. The explosion-proof membrane assembly according to claim 7, characterized in that: Before and after the heat and moisture treatment, the change rate of the unit pressure difference bulging height of the elastic membrane does not exceed 15%, and after the heat and moisture treatment, the random vibration amplitude of the elastic membrane is not greater than 1×10 -3 mm; wherein the heat and humidity treatment refers to storing the elastic film at a temperature of 85°C and a humidity of 85% for 96 hours.

11. The explosion-proof membrane assembly according to claim 7, characterized in that: Before and after the high-temperature treatment, the change rate of the unit pressure difference bulging height of the elastic membrane does not exceed 20%, wherein the high-temperature treatment refers to storing the elastic membrane at a temperature of 125° C. for 96 hours.

12. An explosion-proof valve, comprising a valve body and a valve cover, characterized in that: The valve body is provided with an explosion-proof membrane assembly as described in claims 1-11.

13. The explosion-proof valve according to claim 12, characterized in that: The inner surface of the valve cover is provided with a piercing member.

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