A cryo tube and a method for manufacturing the same

Abstract

The application discloses a cryopreservation tube and a preparation method thereof. The cryopreservation tube is made of plastic containing metal powder and comprises an integrated storage part and a sealed tube opening. The storage part has an inner cavity in communication with the sealed tube opening and used for storing a biological sample, and a plug used for plugging the sealed tube opening. The volume of the inner cavity can be changed by extrusion, and the plug and the sealed tube opening are made of the same material. The cryopreservation tube provided by the application adopts the plug and the sealed tube opening made of the same material, and forms an integrated structure through physical plugging and hot melt bonding, so that the absolute sealing property of the sealed tube opening is ensured, and the problem of leakage and pollution caused by different thermal expansion coefficients under a great temperature difference is avoided.

Description

Technical Field

[0001] This invention relates to the field of laboratory auxiliary equipment technology, and more particularly to the field of cryopreservation tube technology required for biological, cell culture, and single-cell extraction experiments, specifically to a cryopreservation tube and its preparation method. Background Technology

[0002] Cryopreservation tubes are containers used to hold items such as bacterial strains, cells, and biological specimens. They are used to preserve biological specimens in extremely cold environments and to revive them when needed. Cryopreservation tubes are also known as bacterial strain preservation tubes. They mainly consist of three parts: preservation solution, preservation tube, and small ceramic beads. They are containers used in laboratories to preserve or transfer bacterial strains. Generally, bacterial strain preservation tubes contain 25 small ceramic beads for bacterial adsorption and preservation.

[0003] Existing cryovials have a relatively simple structure, generally consisting of a tube body and a cap connected by threads. Current cryovials can be made in relatively large sizes, typically 0.5ml, 1.0ml, 1.5ml, 1.8ml, 2.0ml, 4ml, 5ml, 7ml, and 10ml. The most commonly used cryovial for biological samples is the 2ml size. When selecting a cryovial, the appropriate size should be chosen based on the volume of sample to be frozen, ensuring the sample size generally does not exceed two-thirds of the cryovial's volume. In addition to the conventional threaded seal, utility model patent CN212464678U also provides a fat cryovial, which also uses a threaded seal connection and adds a rotating lifting rod to prevent issues such as loosening of the threads.

[0004] Through research and practical experiments, the applicant discovered that existing cryovials are unsuitable for cryopreserving adipocytes or adipose-derived stem cells. There are two main reasons for this: First, existing cryovials have a relatively large storage space, which allows ice crystals to form during cryopreservation. Since adipocytes have a different morphology than other conventional cells, they are easily damaged. The formation of ice crystals directly leads to adipocyte rupture and death, preventing thawing and reuse. Therefore, conventional cryovials cannot meet the preservation conditions for surviving adipocytes. Second, existing cryovials use threaded seals. The applicant's experiments showed that in the extremely cold liquid nitrogen environment, the difference in thermal expansion coefficients between the cap and the tube can introduce bacteria and viruses, compromising the purity of the adipocytes. Based on these two points, to solve the problem of preventing damage and contamination from freezing ice crystals during the thawing and reuse of surviving adipocytes, a cryovial more suitable for adipocytes is needed. Summary of the Invention

[0005] To address the issue of surviving fat cell resuscitation and reuse being unaffected by freezing ice crystals and / or contamination, this application provides a cryopreservation tube and its preparation method, which solves at least one of the following problems:

[0006] 1. This product is used to address the problem of specimen contamination caused by microbial introduction due to loosening of threads or gaps caused by rapid temperature changes during cryopreservation.

[0007] 2. This invention addresses the problem that existing cryopreservation tubes suffer from fat cell rupture and death due to uncontrollable ice crystal formation during cryopreservation, making them unusable for thawing and reuse.

[0008] 3. Used to solve the problem of cell rupture caused by nonlinear gradient cooling due to poor thermal conductivity of cryopreservation tubes.

[0009] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0010] A cryopreservation tube, made of plastic containing metal powder, includes an integrally formed storage section and a sealed opening. The storage section has an inner cavity communicating with the sealed opening and used for storing biological samples, and a plug for sealing the sealed opening. The volume of the inner cavity can be changed by compression, and the plug and the sealed opening are made of the same material.

[0011] Preferably, the materials used to make cryopreservation tubes include 5%-8% graphite powder, 12%-15% aluminum powder by mass, wherein the particle size of the graphite powder is 15μm-40μm, the particle size of the aluminum powder is 15μm-45μm, 10%-18% acrylonitrile, 22%-30% butadiene, 7%-15% styrene, and the remainder is PE.

[0012] As a key technology for controlling ice crystal formation and protecting fat cells from ice crystal damage, preferably, the maximum distance h between any point in the inner cavity and the inner wall of the storage section is ≤2.2mm.

[0013] The present invention also provides a method for preparing cryovials, which includes the following steps:

[0014] Step S100, pretreatment, mixing acrylonitrile, butadiene, styrene and PE according to a preset ratio and mass parts and preheating, the preheating temperature is 175℃-180℃, and the temperature is held for more than 30 minutes to obtain primary plastic in molten state.

[0015] Step S200: Mixing and stirring. Graphite powder and aluminum powder of preset particle size and mass fraction are mixed and added in batches to the primary plastic in step S100 for stirring. The stirring time is 2-3 hours to obtain the finished plastic. The stirring conditions are: the stirring direction is compound stirring, the stirring speed is 1200 r / min-1500 r / min, and the vibration conditions are: the vibration frequency is greater than or equal to 80 Hz and the amplitude is 0.5 mm-1 mm.

[0016] Step S300, blank preparation, the finished plastic obtained in step S200 is placed into injection molding equipment or extruder to obtain a blank including the sealing tube opening;

[0017] Step S400, finished product production: the blank obtained in step S300 is placed into a blow molding equipment for blow molding and cooling to obtain a cryopreservation tube of the finished product.

[0018] In step S500, the finished plastic obtained in step S200 is extruded using an extruder according to the inner diameter of the sealing pipe to obtain a plug.

[0019] Beneficial effects:

[0020] 1. The cryopreservation tube provided by the present invention uses plugs and sealing tube openings of the same material. Through physical blocking and heat fusion bonding, an integral structure is formed, which ensures the absolute airtightness of the sealing tube opening and avoids the problem of leakage and contamination caused by different coefficients of thermal expansion under extremely large temperature conditions.

[0021] 2. The cryopreservation tube provided by the present invention can eliminate all gases and achieve zero-gas cryopreservation. At the same time, the volume change caused by solid-liquid state change can be overcome by the deformable material.

[0022] 3. This invention uses a unique metal-plastic composite material, which can retain good plasticity and elasticity, and solve the problem of poor thermal conductivity of plastic, which leads to uneven thermal conduction and ice crystals that damage cells. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a front view of a cryopreservation tube structure according to an embodiment of the present invention.

[0025] Figure 2 yes Figure 1 Axonometric drawing.

[0026] Figure 3 yes Figure 1 Longitudinal cross-sectional view.

[0027] Figure 4 This is an isometric view of the cryopreservation tube structure according to another embodiment of the present invention.

[0028] Figure 5 yes Figure 4 Longitudinal cross-sectional view.

[0029] Figure 6 These are the temperature freezing parameter curves of the cryopreservation tubes in groups A, B, and C of Example 3.

[0030] In the diagram: 1-plug; 2-sealing tube; 3-storage section; 4-inner cavity. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] Example 1:

[0035] A cryopreservation tube, see Figures 1-3 As shown, it is made of plastic containing metal powder and includes an integrally molded storage part 3 and a sealing port 2. The storage part 3 has an inner cavity 4 that communicates with the sealing port 2 and is used to store biological samples, and a plug 1 for sealing the sealing port 2. The storage part 3 can change the volume of the inner cavity 4 by compression, and the plug 1 and the sealing port 2 are made of the same material.

[0036] When using the cryovials provided in this embodiment to hold biological specimens, firstly, the entire operation should be carried out in a sterile environment. Biological specimens, such as single cells, single-cell suspensions, microbial strains, and bacterial communities, should first be injected into the inner cavity 4 of the cryovial storage section 3 using a low-flow filling device, such as an existing syringe, or a device that can directly inject the biological specimen through the sealed port 2. The injection should be stopped when the liquid level of the biological specimen is close to filling the inner cavity 4 to avoid overfilling. Secondly, after filling, the storage section 3 should be gently and slowly pressed to gradually deform it and reduce the internal space of the inner cavity 4. This causes the effective storage space of the inner cavity 4 to gradually decrease, allowing the liquid level of the biological specimen stored in the inner cavity 4 to gradually rise until all the air in the inner cavity 4 is expelled and the liquid level reaches the sealed port 2. A small amount of biological specimen overflow is permissible, provided the amount is sufficient or does not affect the actual use, to avoid the presence of air or oxygen within the cryovial. Finally, insert the sterile plug 1 into the sealing port 2. When inserting the plug 1, ensure that the end face of the plug 1 is in contact with the biological specimen, and that the entire insertion process does not allow air to re-enter the cryovial. The plug 1 and the sealing port 2 use a transition fit or interference fit, allowing the material's elasticity to create a seal through deformation, preventing air from entering. To ensure absolute sealing, after the plug 1 is installed, place it near a heat source at 150℃±10℃ to quickly melt the plug 1 and the mating sealing port 2, forming a single, integrated structure. This achieves absolute sealing. Because the same material has the same coefficient of thermal expansion, regardless of temperature differences, the integrated structure will not introduce new bacteria or other microorganisms due to differences in thermal expansion coefficients, thus preventing a decrease in the cleanliness of the biological specimen. It is worth noting that the length of the plug 1 should not be less than 5mm, with 10mm ± 2mm being optimal. Firstly, this effectively ensures the sealing strength between the plug 1 and the sealing tube 2; secondly, it prevents a small amount of heat transfer from affecting the viability of biological specimens near the plug 1 during the heat-fusion bonding of the outer end of the plug 1. Of course, from a safety perspective, a longer plug 1 generally provides higher safety. Based on the material's inherent properties and the limited surface heat-fusion time of approximately 1 second, a plug length greater than 3mm will generally not have a negative thermal impact on the biological specimen. A length of 10mm is preferred, as it is easy to install and provides high stability. It is also worth noting that the aforementioned air purging procedure before installing the plug 1 is necessary, and its main function is:

[0037] 1. After the air is expelled, when the plug 1 is installed, as the plug 1 goes deeper into the sealed tube opening 2, it will occupy the space inside the sealed tube opening 2. If the air is not expelled, firstly, the air will remain in the inner cavity 4 and oxidize the biological specimen. Secondly, as the plug 1 goes deeper, the air will be further compressed, which will increase the pressure inside the inner cavity 4.

[0038] 2. Due to the different densities of liquid and solid water, as freezing progresses, the liquid turns into a solid and the overall volume increases. If the air is not removed, the cryovial will be further subjected to pressure and deform. By appropriately squeezing the cryovial, even if the solid volume increases slightly, there will never be additional pressure inside the cryovial.

[0039] See Figures 1-3 As shown in the figure, this embodiment illustrates a device with a cylindrical sealing port 2 and a disc-shaped storage section 3. Since the two parallel sides of the disc-shaped storage section 3 can be easily compressed, its compression margin can be fully used to withstand the deformation caused by air expulsion or to offset the overall volume change caused by the conversion of biological specimens and reagents in the inner cavity 4 from liquid to solid during freezing. The storage section 3 can be single or multiple, the difference being only in the amount stored; if multiple are used, the overall length may increase. In this case, a spiral winding method can be used to reduce the volume, thus allowing for better placement within the cryopreservation box.

[0040] Example 2:

[0041] See Figures 4-5 As shown, this embodiment provides another cryopreservation tube structure. In the cryopreservation tube structure provided in this embodiment, the storage part 3 is set as a cuboid with a cuboid inner cavity 3, which can also meet the requirements of volume change caused by pressing to release air and solid-liquid state changes. A solid structure is formed by extending along the length direction at any end of the storage part 3. A sealing tube port 2 for installing the plug 1 is provided on the solid structure. This structure can store more biological samples under the same length conditions. Other working principles are the same as in embodiment 1, and will not be described in detail in this embodiment.

[0042] Example 3:

[0043] This embodiment describes the cryopreservation tube material in Embodiment 1 or Embodiment 2. This embodiment provides a material that can simultaneously achieve both thermal conductivity and structural toughness. Specifically, the material for making the cryopreservation tube includes 5%-8% graphite powder, 12%-15% aluminum powder by mass, wherein the particle size of the graphite powder is 15μm-40μm, the particle size of the aluminum powder is 15um-45um, 10%-18% acrylonitrile, 22%-30% butadiene, 7%-15% styrene, and the remainder is PE.

[0044] Thermal conductivity refers to the property of a material to conduct heat, expressed as thermal conductivity λ, according to the formula...

[0045] λ=Qδ / At(T2-T1)

[0046] λ—thermal conductivity (W / (mK)); Q—heat conducted (J);

[0047] A—thermal conduction area (m²); δ—material thickness (m²);

[0048] t—heat conduction time (s); (T2-T1)—temperature difference across the material (k)

[0049] According to the above formula, the only difference between this embodiment and existing plastic cryopreservation tubes in terms of heat conduction is the amount of heat conducted per unit time and per unit area with the same thickness under the same temperature difference. As one of the most demanding and fragile biological cells requiring cryopreservation conditions, fat cells require even higher standards for linear, successive cooling to minimize uneven heating and inconsistent heat conduction efficiency that could lead to ice crystal formation. Therefore, in the cryopreservation of other microorganisms or cells, the actual execution of the freezing program does not require very strict adherence; simply following the requirements of the programmed cooling box for gradient cooling is sufficient. Typically, the actual temperature experienced by the biological specimen is assumed to be the programmed temperature. However, during actual cryopreservation, the applicant found that existing cryopreservation boxes, after programmed cryopreservation, resulted in a large number of fat cells dying due to rupture after thawing. The rupture was caused by ice crystals. To verify the consistency between the actual temperature of the biological specimen and the programmed temperature of the cryopreservation box, the applicant conducted the following comparative test.

[0050] Experiment content:

[0051] Experimental equipment: One -80℃ freezer, specifically an AIPU I NS AP-86-30LA ultra-low temperature laboratory freezer with a volume of 30L. Three cryovials: 5ml plastic cryovials (Group A); metal tubes with stoppers as a control (Group B); and cylindrical 5ml test cryovials made of the material described in this embodiment (Group C). A sufficient amount of alcohol for temperature testing.

[0052] Experimental Method: 4 ml of 26°C alcohol was injected into cryovials in groups A, B, and C respectively. The tubes were first placed in a cryovial box, which was then placed in a freezer set to -80°C. The cryovial program lowered the temperature by 1°C per minute. After 20 minutes, the tubes were removed, and the alcohol temperature in each group was quickly measured. The tubes were then returned to the 26°C alcohol container to return to room temperature. Another 4 ml of room temperature alcohol was added, and the tubes were placed in the -80°C freezer again, waiting 30 minutes before being removed and the temperature measured again. This process was repeated for 40, 50, 60, 70, and 80 minutes. It is important to note that after each test, at least 10 minutes should be allowed for the freezer temperature to reach the predetermined temperature and remain stable before the next measurement to ensure accuracy. The data obtained using a THERMOMETER YET-710 recorder are shown in Table 1 below.

[0053]

[0054] Table 1. Alcohol temperatures of different cryovials under the same freezing conditions.

[0055] See Figure 6 As shown in Table 1 above, the actual temperature of the biological specimens inside the cryopreservation box depends on the cryopreservation tubes they contain. Group A uses existing plastic cryopreservation tubes, which exhibit the worst linearity and gradient in their surface freezing temperature curves. The cooling rate fluctuates across different temperature ranges, and the actual temperature within the cryopreservation tube deviates most significantly from the programmed temperature, resulting in unsatisfactory performance. Group B uses non-professional cryopreservation tubes. Because Group B is made of metal with high thermal conductivity, its actual temperature data is closest to the programmed temperature, although a slight deviation still exists. The applicant's analysis suggests that this deviation is due to the time required for heat exchange between the metal tube and the alcohol itself, which objectively cannot achieve real-time synchronization, resulting in a slight lag. However, because the metal tube has excellent thermal conductivity, this lag is linear and does not exhibit the non-linear temperature drop seen in Group A due to different temperature environments.

[0056] A comparison of groups A and B reveals that the better the thermal conductivity of the material, the better the correlation between its actual internal temperature and the programmed temperature, resulting in a more consistent temperature change curve. Conversely, the worse the thermal conductivity, the worse the correlation between its actual internal temperature and the programmed temperature, leading to greater fluctuations and a more dispersed temperature change curve. Group C falls between groups A and B, maintaining a curve trend largely consistent with the programmed group. This indicates that the cryovial material in group C can linearly express the programmed temperature under different temperature environments, avoiding gradual or sudden temperature drops at different stages. This minimizes the risk of ice crystal formation damaging biological specimens, especially fat cells. The reason for this success lies in the addition of graphite and aluminum powder to the cryovial material, improving its thermal conductivity while retaining its extreme cold resistance and toughness. This material achieves excellent results in cryovials, particularly in fat cell programs, significantly reducing the probability of fat cell death due to ice crystal formation.

[0057] Furthermore, relying solely on temperature control is insufficient. Since the ultimate goal of fat cell cryopreservation is reuse, the fat cells need to be reintroduced into the human body, requiring the absolute viability of the fat cells. Theoretically, the best way to avoid ice crystal damage to fat cells is to arrange the fat cells neatly as individual cells, denying them space for ice crystal growth. This would absolutely prevent ice crystal damage. However, manufacturing cryovials specifically for fat cell size is impractical. Even if they could be manufactured effectively, they wouldn't be able to store a sufficient quantity of applicable fat cells. Using conventionally structured cryovials, even the smallest size, doesn't solve this problem. Through analysis of ice crystal formation and the number of damaged fat cells, the applicant, using a unique thickness control method to collect surviving fat cell data, found that the area closest to the temperature source (specifically referring to low temperature) within the stored fat cell space is less prone to ice crystal damage. Conversely, the central area, further away from the cryovial wall, is more susceptible to cell damage. The applicant's thickness control method is as follows:

[0058] Using the same biological specimens, in this embodiment, the biological specimens were fat samples from the Department of Burns and Plastic Surgery, West China Hospital of Sichuan University, prepared from fat cells using an ultrasonic ablation device manufactured by Chengdu Daosheng Biotechnology Co., Ltd. (Japanese Patent No. JP7136495B2). The obtained fat cells were implanted into sealed plastic tubes with radii of 0.5 mm, 1 mm, 1.5 mm, 2.2 mm, 2.5 mm, 3 mm, and 5 mm, respectively, and placed in the same cryopreservation box for cryopreservation. After the temperature stabilized at -80°C for 24 hours, they were transferred to liquid nitrogen for 48 hours. After thawing / recovery, and following routine thawing / recovery, the tubes were centrifuged at 300g. After centrifugation, the thickness of the oil layer on the upper surface of the plastic tubes was directly observed after 30 minutes to obtain the proportion of damaged fat cells. It's worth noting that due to the unique characteristics of adipocytes, methods such as trypan blue staining or cell counting are unnecessary. Since damaged adipocytes float on the surface as an oil layer, the presence of this oil layer is sufficient to determine the presence of damaged or ruptured adipocytes. More damage results in a thicker oil layer on the surface; conversely, if the adipocytes are undamaged or minimally damaged, there will be little or no oil on the surface. Because all sealed plastic tubes of different diameters are cylindrical, the diameter does not affect the assessment of oil thickness when containing the same single-cell suspension. Therefore, the relationship between cryopreservation tube size and adipocyte survival can be determined solely by the thickness of the floating oil. Experimental results show that adipocytes in sealed plastic tubes with radii of 0.5mm-2.2mm have virtually no oil or only a few scattered oil particles floating in them; however, 2.5mm, 3mm, and 5mm sealed plastic tubes all show significant oil thicknesses of 1.4mm, 2.4mm, and 6mm, respectively. This demonstrates a positive correlation between oil thickness and the diameter of the sealed plastic tube. It is worth noting that the thickness of the grease is determined by visual observation of its adhesion to the inner wall of the sealed plastic tube. It is also worth noting that due to limitations in the applicant's experimental materials, the above experiments were able to qualitatively determine the relationship between the size of the cryopreservation space and the degree of damage to individual fat cells, but detailed quantitative studies were not conducted on the specific dimensions. However, the optimal dimensions are expected to be between 2.2mm and 2.5mm, but closer to 2.2mm. Therefore, as a necessary factor in controlling ice crystal formation and a key technology for protecting fat cells from ice crystal damage, in this embodiment, the maximum distance h between any point in the inner cavity 4 and the inner wall of the storage section 3 is ≤ 2.2mm.

[0059] Example 4:

[0060] The present invention also provides a method for preparing cryovials, which includes the following steps:

[0061] Step S100, pretreatment, mixing acrylonitrile, butadiene, styrene and PE according to a preset ratio and mass parts and preheating, the preheating temperature is 175℃-180℃, and the temperature is held for more than 30 minutes to obtain primary plastic in molten state.

[0062] Step S200: Mixing and stirring. Graphite powder and aluminum powder, according to a preset particle size and mass fraction, are mixed and added in batches to the primary plastic from step S100 for stirring. The stirring time is 2-3 hours to obtain the finished plastic. The stirring conditions are: compound stirring direction, stirring speed of 1200-1500 r / min, and vibration conditions of a vibration frequency greater than or equal to 80 Hz and an amplitude of 0.5 mm-1 mm. This step is crucial to the invention. Due to the special properties of the materials, the primary plastic in the molten state has significant adhesion resistance. The mixed graphite powder and aluminum powder, due to their extremely small particle size, cannot move independently under gravity. However, relying solely on stirring cannot achieve a good stirring effect. Therefore, combining vibration and compound stirring is key to achieving uniform mixing of the materials. The compound stirring mentioned in this step refers to having two or more stirring shafts, with the directions of the shafts not parallel, preferably perpendicular. Compound stirring also refers to single-shaft stirring, where multiple shafts work together to achieve varied, complex, and periodic changes in the force on the material, thereby achieving uniform mixing.

[0063] Step S300, blank preparation, the finished plastic obtained in step S200 is placed into injection molding equipment or extruder to obtain a blank including the sealing tube opening;

[0064] Step S400, finished product production: the blank obtained in step S300 is placed into a blow molding equipment for blow molding and cooling to obtain a cryopreservation tube of the finished product.

[0065] In step S500, the finished plastic obtained in step S200 is extruded using an extruder according to the inner diameter of the sealing pipe to obtain a plug.

[0066] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cryopreservation tube, characterized in that: Made of plastic containing metal powder, it includes an integrally molded storage part (3) and a sealing port (2). The storage part (3) has an inner cavity (4) that communicates with the sealing port (2) and is used to store biological samples, and a plug (1) for sealing the sealing port (2). The storage part (3) can change the volume of the inner cavity (4) by compression, and the plug (1) and the sealing port (2) are made of the same material. The materials used to make cryovials include 5%-8% graphite powder, 12%-15% aluminum powder (with a particle size of 15μm-40μm and a particle size of 15μm-45μm), 10%-18% acrylonitrile, 22%-30% butadiene, 7%-15% styrene, and the remainder is PE. The maximum distance h between any point in the inner cavity (4) and the inner wall of the storage section (3) is ≤2.2mm.

2. A method for preparing cryovials, used to prepare the cryovials of claim 1, characterized in that, Includes the following steps: Step S100, pretreatment, mixing acrylonitrile, butadiene, styrene and PE according to a preset ratio and mass parts and preheating, the preheating temperature is 175℃-180℃, and the temperature is held for more than 30 minutes to obtain primary plastic in molten state. Step S200: Mixing and stirring. Graphite powder and aluminum powder of preset particle size and mass fraction are mixed and added in batches to the primary plastic in step S100 for stirring. The stirring time is 2-3 hours to obtain the finished plastic. The stirring conditions are: the stirring direction is compound stirring, the stirring speed is 1200 r / min-1500 r / min, and the vibration conditions are: the vibration frequency is greater than or equal to 80 Hz and the amplitude is 0.5 mm-1 mm. Step S300, blank preparation, the finished plastic obtained in step S200 is placed into the injection molding equipment or extruder to obtain a blank including the sealed tube opening (2); Step S400, finished product production: the blank obtained in step S300 is placed into a blow molding equipment for blow molding and cooling to obtain a cryopreservation tube of the finished product. In step S500, the finished plastic obtained in step S200 is extruded using an extruder according to the inner diameter of the sealing pipe opening (2) to obtain a plug (1).

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