Vacuum bag blow molding material and preparation method thereof

Abstract

The invention belongs to the technical field of packaging materials, and particularly relates to a vacuum bag blow molding material and a preparation method thereof. The method comprises the following steps: (1) uniformly mixing a high-molecular compound, dihydric alcohol, carboxylic acid and a nano inorganic material in proportion, and pre-plasticizing to prepare a base material; and (2) uniformly mixing the base material and the organosilicon compound in proportion, and performing melt extrusion granulation to prepare the vacuum bag blow molding material. Polyvinyl alcohol is modified through a blending melting technology, a modifier with high thermal stability and mechanical performance is selected, heat resistance and strength are improved, processing and high temperature resistance are improved through plasticizing modification by chemical and physical methods, an organosilicon compound is introduced to optimize a microstructure, connection strength and sealing performance are enhanced, and weather resistance and aging resistance are improved. And the performance and durability of the vacuum bag material are enhanced. In preparation, reaction conditions are accurately controlled, a catalyst and nano zinc oxide particles are added, the material performance is further optimized, and the service life of the vacuum bag is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of packaging materials, and in particular relates to a vacuum bag blow molding material and a preparation method thereof. Background Art

[0002] Vacuum packaging technology plays an irreplaceable role in the fields of food, medicine, electronics, etc. with its excellent oxygen barrier, moisture-proof and fresh-keeping properties. As the core carrier of vacuum packaging, the performance of vacuum bag materials directly determines the reliability and applicability of packaging. At present, most of the vacuum bag materials on the market are based on polyethylene (PE), polypropylene (PP) or polyvinyl chloride (PVC). Although these materials have certain processing convenience and cost advantages, their inherent defects seriously limit the expansion of high-end application scenarios: Insufficient heat resistance: Traditional materials (such as PE) have a low softening point (usually <120°C), and are prone to deformation or thermal decomposition during high-temperature sterilization or heat sealing processes, resulting in sealing failure; Imbalance between mechanical strength and toughness: Although materials such as PVC have high rigidity, they have poor toughness and are easily damaged by external impact during transportation or storage; and toughened modified materials often have a significant decrease in mechanical properties due to excessive plasticization; Barrier performance limitations: PE / PP has poor barrier properties to oxygen and water vapor, and it is difficult to meet the long-term protection needs of high value-added products (such as precision electronic components and medical devices); Environmental and health risks: A large amount of plasticizers (such as phthalates) need to be added during PVC processing, which poses a migration risk and does not meet the safety requirements for food contact materials.

[0003] In response to the above problems, existing technologies attempt to improve material performance through blending modification, nanofilling or surface coating. For example: high barrier materials: polyvinylidene chloride (PVDC) or ethylene-vinyl alcohol copolymer (EVOH) is used to improve barrier properties, but its high crystallinity leads to harsh processing temperatures and greatly increases costs; heat-resistant modification: the introduction of inorganic fillers (such as talcum powder) or cross-linking agents improves thermal stability, but excessive addition will deteriorate the flexibility and transparency of the material; environmentally friendly alternative materials: explore bio-based materials such as polylactic acid (PLA), but its heat resistance, moisture resistance and mechanical strength still cannot meet the stringent requirements of vacuum bags.

[0004] In addition, polyvinyl alcohol (PVA) is considered a potential alternative material due to its high barrier properties, biodegradability and chemical stability, but its high crystallinity and strong hydrogen bonding make melt processing difficult. Conventional plasticizing techniques (such as glycerol plasticizing) can reduce processing temperatures, but will significantly weaken the heat resistance and mechanical strength of the material. In addition, the existing solutions for improving the sealing of materials through silicone modification often lead to interface stratification due to the poor compatibility between silicone and the substrate, or rely on high-cost chemical grafting processes, making it difficult to achieve large-scale applications.

[0005] Therefore, there is an urgent need to develop a vacuum bag blow molding material that has excellent heat resistance, high barrier properties, strong mechanical properties and environmental protection characteristics. At the same time, it is necessary to break through the bottleneck of the difficulty in synergistic optimization of processability, cost and performance in existing modification technologies, so as to meet the urgent needs of diversified application scenarios for high-performance vacuum packaging. Summary of the invention

[0006] The technical solution of the present invention aims at solving the technical problems such as insufficient heat resistance, low mechanical strength and poor sealing performance in traditional solutions, and provides a vacuum bag blow molding material and a preparation method thereof.

[0007] The main purposes of the present invention are: 1. To improve the heat resistance of materials used in preparing vacuum bags.

[0008] 2. Strengthen the mechanical strength of materials.

[0009] 3. The vacuum bag made of the material has excellent sealing performance.

[0010] To achieve the above objectives, the present invention adopts the following technical solutions.

[0011] A method for preparing a vacuum bag blow molding material comprises: (1) uniformly mixing a polymer compound, a diol, a carboxylic acid and a nano inorganic material in proportion, and pre-plasticizing the mixture to prepare a substrate.

[0012] (2) The base material and the organosilicon compound are mixed evenly in proportion, melt-extruded and granulated to prepare a vacuum bag blow molding material.

[0013] Preferably, the polymer compound in step (1) is polyvinyl alcohol; the diol in step (1) is ethylene glycol; the carboxylic acid in step (1) is stearic acid; and the nano-inorganic material in step (1) is nano-zinc oxide.

[0014] Preferably, in step (1), the polymer compound, diol, carboxylic acid and nano-inorganic material are uniformly mixed in a mass ratio of (15-17): (2-3): (3-5): 1.5.

[0015] Preferably, the mixing in step (1) is carried out by stirring for 1 to 2 hours at a temperature of 130 to 140°C and a rotation speed of 300 to 500 r / min.

[0016] Preferably, the pre-plasticization in step (1) is carried out in an environment with a temperature of 80 to 100° C. for 7 to 9 hours.

[0017] Preferably, the organosilicon compound in step (2) is prepared by the following method: trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate are uniformly mixed in a mass ratio of 3:(2-3):1, and concentrated sulfuric acid in an amount of 1-2 wt% of the total mass is added in a nitrogen atmosphere at a temperature of 40-50°C, and the mixture is kept warm for reaction for 1-2 h, and then anhydrous sodium carbonate is added to neutralize the concentrated sulfuric acid, and the pH value is adjusted to 3-4 with hydrochloric acid, and the mixture is kept warm for reaction for 1-2 h in an environment of 50-70°C, and then distilled water in an amount of 10-20 wt% of the total mass is added at an addition rate of 60 mL / min, and the mixture is reacted for 6-8 h to obtain an organosilicon compound.

[0018] Preferably, in step (2), the substrate and the organosilicon compound are uniformly mixed in a mass ratio of 3:(1-2).

[0019] Preferably, the melt extrusion granulation in step (2) is performed by extrusion granulation using a twin-screw extruder at a temperature of 120 to 160°C.

[0020] A vacuum bag blow molding material.

[0021] In the technical solution of the present invention, the core is to modify polyvinyl alcohol by blending and melting technology, aiming to improve the heat resistance of the material and enhance its mechanical strength. In the blending and melting process, a modifier with high thermal stability and good mechanical properties is first selected and uniformly mixed with polyvinyl alcohol. The modifier can effectively interact with the polyvinyl alcohol molecular chain, thereby maintaining the structural stability of the material at high temperatures and preventing it from degrading its performance due to thermal decomposition. At the same time, the addition of the modifier can also enhance the interaction force between the polyvinyl alcohol molecular chains to a certain extent, improve its mechanical strength, and make the prepared vacuum bag material show better toughness and durability when subjected to external forces.

[0022] Environmentally friendly materials such as polyvinyl alcohol (PVA) have attracted much attention due to their biodegradable properties. Although polyvinyl alcohol has many advantages, such as its excellent chemical stability, good film-forming properties and environmental friendliness, its high crystallinity and strong hydrogen bonding between molecules make the processing process quite challenging. In order to achieve its effective processing, it is necessary to use plasticization modification technology to reduce its melting temperature and weaken the interaction between molecules, thereby improving its processing performance and application range. In the current technical field, the plasticization modification of polyvinyl alcohol (PVA) is mainly achieved by chemical and physical methods. Chemical modification involves the introduction of new functional groups to improve the molecular structure, thereby enhancing its water resistance, solvent resistance and corrosion resistance. However, this method has the problems of high cost, high toxicity and difficulty in achieving continuous production. In contrast, physical modification destroys the hydrogen bonds between molecules by adding small molecules or oligomers, changes the crystallization state of the material, does not require chemical reactions, and has the advantages of simple operation, high efficiency and easy industrialization. Among physical modifications, blending modification is its main form of realization. In the technical scheme of the present invention, polyvinyl alcohol (PVA) is plasticized and modified by ethylene glycol, which significantly expands the window of thermal processing, thereby facilitating the realization of industrial continuous production. The material exhibits excellent gas barrier properties, sealing properties and high temperature resistance. Specifically, ethylene glycol, as a plasticizer, can penetrate into the molecular chains of polyvinyl alcohol, effectively weaken the hydrogen bonding force between molecules, reduce the melting temperature and viscosity of polyvinyl alcohol, and make it easier to flow and shape during processing. At the same time, the addition of ethylene glycol does not significantly affect the chemical stability of polyvinyl alcohol, ensuring the long-term performance of the material. During the preparation process, the addition ratio of ethylene glycol and the processing conditions are optimized to ensure the maximization of the plasticization modification effect. The modified polyvinyl alcohol material, while maintaining the original excellent performance, significantly improves the heat resistance and processing performance, making it suitable for higher temperature blow molding processes, while ensuring the gas barrier and sealing properties of vacuum bag products.

[0023] In addition, in the technical solution of the present invention, another core element is to provide a special organosilicon compound. The compound enhances the connection strength and sealing between the components in the material by optimizing the microstructure of the substrate. This organosilicon compound can form good compatibility with polyvinyl alcohol and ethylene glycol. During the preparation of the material, the organosilicon compound is evenly dispersed in the polyvinyl alcohol matrix, and its active functional groups react with the hydroxyl groups of polyvinyl alcohol to form a stable chemical bond. This chemical bonding not only enhances the overall strength of the material, but also significantly improves the sealing performance of the material, ensuring that the vacuum bag will not leak during use. At the same time, the addition of the organosilicon compound also improves the weather resistance and anti-aging properties of the material. When exposed to light, high temperature or humidity for a long time, the organosilicon compound can effectively resist the erosion of the material properties by external factors and extend the service life of the vacuum bag.

[0024] The present invention relates to an organosilicon compound prepared by copolymerizing trifluoropropyl trimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate. By precisely controlling the copolymerization ratio of the above monomers, the organosilicon compound exhibits excellent stability, thereby improving the use performance of vacuum bag blow molding materials. The use of octamethylcyclotetrasiloxane effectively avoids the condensation of hydroxyl groups to form active organic groups under high temperature conditions, thereby preventing adverse effects on the surface of the substrate and significantly enhancing the sealing of the material. In particular, the selective use of trifluoropropyl trimethylcyclotrisiloxane is used to modify the substrate, and the high electronegativity and low surface tension characteristics of the fluorine element are utilized to make the fluorine-containing chain segments aggregate in the outer layer of the substrate, greatly reducing the surface tension of the substrate, and the protective effect of the CF bond significantly improves the durability of the substrate cloth. In addition, the polymerization reaction of nano zinc oxide particles in the substrate and the organosilicon compound further improves the durability and stability of the material, and the uniform distribution of the particles also enhances the consistency inside the material, thereby extending the service life of the vacuum bag.

[0025] In the preparation process, trifluoropropyl trimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate are first mixed in a certain proportion and copolymerized under the protection of inert gas. By adjusting the reaction temperature and reaction time, the progress of the copolymerization reaction can be accurately controlled to obtain an organosilicon compound with specific properties. In addition, adding an appropriate amount of catalyst to the reaction system can further improve the reaction rate and the purity of the product. In the obtained organosilicon compound, the fluorine element of trifluoropropyl trimethylcyclotrisiloxane forms a stable chemical bond with the hydrogen element in the substrate, which not only improves the heat resistance of the material, but also gives the material excellent anti-aging properties. At the same time, the introduction of octamethylcyclotetrasiloxane enables the material to maintain a stable structure at high temperatures, avoiding the performance degradation caused by hydroxyl condensation. In order to further optimize the performance of the material, an appropriate amount of nano zinc oxide particles can also be added during the preparation process. These particles can undergo polymerization reaction with the organosilicon compound to form a more compact network structure, thereby improving the strength and toughness of the material. In addition, the uniform distribution of nano zinc oxide particles can effectively prevent cracks and breakage in the material during use, further extending the service life of the vacuum bag.

[0026] The present invention is beneficial in that: the present invention modifies polyvinyl alcohol by blending and melting technology, and selects modifiers with high thermal stability and mechanical properties to improve heat resistance and strength. Polyvinyl alcohol is plasticized and modified by chemical and physical methods, mainly by blending physically, and ethylene glycol is used as a plasticizer to improve processing and high temperature resistance. The introduction of organic silicon compounds optimizes the microstructure, enhances the connection strength and sealing, and improves weather resistance and aging resistance. Organic silicon is prepared by specific compounds to enhance the performance and durability of vacuum bag materials. During the preparation, the reaction conditions are precisely controlled, and catalysts and nano zinc oxide particles are added to further optimize the material properties and extend the service life of the vacuum bag. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0028] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0029] Example 1: A method for preparing a vacuum bag blow molding material, the method comprising: (1) uniformly mixing polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide in a mass ratio of 15:2:3:1.5, stirring for 2 h in an environment at a temperature of 130 °C and a rotation speed of 300 r / min, and then pre-plasticizing in an environment at a temperature of 80 °C for 9 h to prepare a substrate.

[0030] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were uniformly mixed in a mass ratio of 3:2:1, and concentrated sulfuric acid (1 wt %) was added in a nitrogen atmosphere at 40 °C for 2 h. Anhydrous sodium carbonate was then added to neutralize the concentrated sulfuric acid, and the pH value was adjusted to 3 with hydrochloric acid. The mixture was reacted at 50 °C for 2 h. Distilled water (10 wt %) was then added at a rate of 60 mL / min for 8 h to obtain an organosilicon compound.

[0031] (3) The base material and the organosilicon compound are uniformly mixed in a mass ratio of 3:1, and the mixture is extruded and granulated using a twin-screw extruder at a temperature of 120°C to prepare a vacuum bag blow molding material.

[0032] The blow molding material prepared in this example was subjected to performance testing, and the specific characterization results are as follows.

[0033] Mechanical properties testing: The prepared material in this example was cut into standard dumbbell-shaped small specimens, and the tensile strength and elongation at break were tested using an electronic universal testing machine in accordance with the national standard GB / T1040.3-2006. The speed was set to 100 mm / min, and 5 specimens were tested in each group. The final results were averaged.

[0034] Oxygen permeation test: Use a special film sampler with uniform thickness and no quality problems to cut into test samples with a diameter of 97mm. Use a differential pressure gas permeameter to test the oxygen permeation of the film in accordance with GB / T1038-2000. Perform performance tests in an environment with a temperature of 23°C and a humidity of 50%RH. Each group of test samples is tested 5 times, and the final results are averaged.

[0035] Barrier property test: The material prepared in this example was prepared into a test sample with a size of 2×2×0.1 cm. The initial mass of the test sample was weighed. The test sample was immersed in edible oil at a temperature of 25°C for 1 day and then taken out. The excess edible oil on the surface was absorbed with oil-absorbing paper and the mass was weighed again. The oil absorption rate was calculated according to the following formula. Five samples were tested in each group of experiments and the final result was averaged.

[0036]

[0037] Where: ——Material oil absorption rate, %.

[0038] ——The initial mass of the test sample, mg.

[0039] ——Mass after oil immersion, mg.

[0040] Thermogravimetric analysis: In a nitrogen atmosphere, the temperature was 25 °C and the heating rate was 25 °C / min. The temperature was raised to 800 °C and the performance was tested using a thermogravimetric analyzer. The specific characterization results are shown in Table 1.

[0041] Table 1: Characterization results of Example 1:

[0042] By analyzing the above characterization results, it can be found that the vacuum bag blow molding material prepared by the present invention has excellent performance in terms of sealing, thermal stability, mechanical properties, etc. Specifically, the oxygen permeability of the material is 27.78 cm 3 / (m 2 ·d·0.1MPa), showing good sealing. In addition, the mechanical properties of the material are also excellent, with tensile strength and elongation at break reaching 54.64 MPa and 831.7% respectively, with high strength and toughness, and can meet the needs of various application scenarios. In summary, the vacuum bag blow molding material of the present invention has excellent comprehensive performance and is expected to be widely used in food packaging, medical devices and other fields. At the same time, in the process of in-depth analysis of the thermal stability of the material, a significant phenomenon was observed: as the temperature gradually increased, the quality of the test sample showed a significant downward trend. This thermal decomposition process can be divided into three different stages in detail. First, in the first stage, that is, when the temperature range increased from 270 ℃ to 470 ℃, the fracture of the carbon-silicon bond was noticed, and the fracture of this chemical bond directly led to the decomposition of small molecule polymers. Then, in the second stage, that is, in the range of temperature from 470 ℃ to 600 ℃, the fracture of the silicon-oxygen bond became dominant, and this process was accompanied by a significant loss of quality. Finally, in the third stage, when the temperature ranges from 600 °C to 800 °C, the decomposition rate slows down, and this stage mainly involves the decomposition of the residual carbonaceous part. Through a comprehensive evaluation of the thermogravimetric analysis results, it can be concluded that the prepared materials show quite good thermal stability.

[0043] Example 2: A method for preparing a vacuum bag blow molding material, the method comprising: (1) uniformly mixing polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide in a mass ratio of 16:2.5:4:1.5, stirring for 1.5 h in an environment at a temperature of 135 °C and a rotation speed of 400 r / min, and then pre-plasticizing in an environment at a temperature of 90 °C for 8 h to prepare a substrate.

[0044] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were uniformly mixed in a mass ratio of 3:2.5:1, and concentrated sulfuric acid (1.5 wt%) was added in a nitrogen atmosphere at a temperature of 45 °C. The mixture was kept warm for 1.5 h. Anhydrous sodium carbonate was then added to neutralize the concentrated sulfuric acid, and the pH value was adjusted to 3.5 with hydrochloric acid. The mixture was kept warm for 1.5 h at a temperature of 60 °C. Distilled water (15 wt%) was then added at a rate of 60 mL / min. The mixture was reacted for 7 h to obtain an organosilicon compound.

[0045] (3) The base material and the organosilicon compound are uniformly mixed in a mass ratio of 2:1, and the mixture is extruded and granulated using a twin-screw extruder at a temperature of 140°C to prepare a vacuum bag blow molding material.

[0046] The blow molding material prepared in this example was subjected to performance testing, and the specific characterization results are as follows, and the specific characterization results are shown in Table 2.

[0047] Table 2: Characterization results of Example 2:

[0048] Example 3: A method for preparing a vacuum bag blow molding material, the method comprising: (1) uniformly mixing polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide in a mass ratio of 17:3:5:1.5, stirring for 1 h in an environment at a temperature of 140°C and a rotation speed of 500 r / min, and then pre-plasticizing at a temperature of 100°C for 7 h to prepare a substrate.

[0049] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were uniformly mixed in a mass ratio of 3:3:1, and concentrated sulfuric acid (2 wt% of the total mass) was added in a nitrogen atmosphere at a temperature of 50 °C. The mixture was kept warm for 1 h. Anhydrous sodium carbonate was then added to neutralize the concentrated sulfuric acid, and the pH value was adjusted to 4 with hydrochloric acid. The mixture was kept warm for 1 h at a temperature of 70 °C. Distilled water (20 wt% of the total mass) was then added at a rate of 60 mL / min. The mixture was reacted for 6 h to obtain an organosilicon compound.

[0050] (3) The base material and the organosilicon compound are uniformly mixed in a mass ratio of 3:2, and the mixture is extruded and granulated using a twin-screw extruder at a temperature of 160°C to prepare a vacuum bag blow molding material.

[0051] The blow molding material prepared in this example was subjected to performance testing, and the specific characterization results are as follows, and the specific characterization results are shown in Table 3.

[0052] Table 3: Characterization results of Example 3:

[0053] Comparative Example 1: A method for preparing a vacuum bag blow molding material. The specific preparation method is the same as that of Example 2. Only the substrate component in the present invention is changed in the comparative example. The specific characterization results and operation process are as follows.

[0054] (1) Polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide were mixed in a mass ratio of 16:5:4:1.5, stirred at a temperature of 135 °C and a rotation speed of 400 r / min for 1.5 h, and then kept at a temperature of 90 °C for 8 h for pre-plasticization to prepare a substrate.

[0055] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were uniformly mixed in a mass ratio of 3:2.5:1, and concentrated sulfuric acid (1.5 wt%) was added in a nitrogen atmosphere at a temperature of 45 °C. The mixture was kept warm for 1.5 h. Anhydrous sodium carbonate was then added to neutralize the concentrated sulfuric acid, and the pH value was adjusted to 3.5 with hydrochloric acid. The mixture was kept warm for 1.5 h at a temperature of 60 °C. Distilled water (15 wt%) was then added at a rate of 60 mL / min. The mixture was reacted for 7 h to obtain an organosilicon compound.

[0056] (3) The base material and the organosilicon compound are uniformly mixed in a mass ratio of 2:1, and the mixture is extruded and granulated using a twin-screw extruder at a temperature of 140°C to prepare a vacuum bag blow molding material.

[0057] The blow molding material prepared in this example was subjected to performance testing, and the specific characterization results are as follows, and the specific characterization results are shown in Table 4.

[0058] Table 4: Characterization results of Comparative Example 1:

[0059] Analyzing the above characterization results, it is found that the vacuum bag blow molding material prepared in this example has a large data difference in sealing compared with Example 2. After further analysis, ethylene glycol is excessively present between the molecular chains of the PVA matrix. Although it plays a certain lubricating role, it also enhances the mobility of the PVA molecular chains and expands the molecular gap, resulting in a significant increase in oxygen permeability, thereby reducing the sealing performance of the vacuum bag. In addition, the introduction of too much ethylene glycol also affects the mechanical properties of the blow molding material. Due to the interaction between the ethylene glycol molecules and the PVA matrix molecular chains, the tensile strength of the material is reduced, and the elongation at break also shows a decreasing trend. This decline in mechanical properties further weakens the durability and reliability of the vacuum bag. Therefore, when preparing vacuum bag blow molding materials, it is necessary to strictly control the amount of ethylene glycol added to avoid its adverse effects on material properties.

[0060] Comparative Example 2: A method for preparing a vacuum bag blow molding material. The specific preparation method is the same as that of Example 2. In the comparative example, only the substrate component in the present invention is changed, and stearic acid in the substrate is not used. The specific characterization results and operation process are as follows.

[0061] (1) Polyvinyl alcohol, ethylene glycol and nano zinc oxide were mixed in a mass ratio of 16:2.5:1.5, stirred at a temperature of 135 °C and a rotation speed of 400 r / min for 1.5 h, and then kept at a temperature of 90 °C for 8 h for pre-plasticization to prepare a substrate.

[0062] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were uniformly mixed in a mass ratio of 3:2.5:1, and concentrated sulfuric acid (1.5 wt%) was added in a nitrogen atmosphere at a temperature of 45 °C. The mixture was kept warm for 1.5 h. Anhydrous sodium carbonate was then added to neutralize the concentrated sulfuric acid, and the pH value was adjusted to 3.5 with hydrochloric acid. The mixture was kept warm for 1.5 h at a temperature of 60 °C. Distilled water (15 wt%) was then added at a rate of 60 mL / min. The mixture was reacted for 7 h to obtain an organosilicon compound.

[0063] (3) The base material and the organosilicon compound are uniformly mixed in a mass ratio of 2:1, and the mixture is extruded and granulated using a twin-screw extruder at a temperature of 140°C to prepare a vacuum bag blow molding material.

[0064] The blow molding material prepared in this example was subjected to performance testing, and the specific characterization results are as follows, and the specific characterization results are shown in Table 5.

[0065] Table 5: Characterization results of Comparative Example 2:

[0066] By analyzing the above characterization results, it is found that the vacuum bag blow molding material prepared in this example has a large performance difference compared with Example 2. Specifically, in the case where stearic acid is not added in the comparative example, the modification effect of the organosilicon compound on the substrate is too strong, resulting in a decrease in key indicators such as the mechanical properties, heat resistance and oil absorption rate of the blow molding material. In Example 2, by adding an appropriate amount of stearic acid, the degree of modification of the substrate by the organosilicon compound is effectively controlled, thereby preparing a vacuum bag blow molding material with better comprehensive performance.

[0067] Comparative Example 3: A method for preparing a vacuum bag blow molding material. The specific preparation method is the same as that of Example 2, except that the specific organosilicon compound in the present invention is not prepared and used. The specific characterization results and operation process are as follows.

[0068] (1) Polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide were mixed in a mass ratio of 16:2.5:4:1.5, stirred at a temperature of 135 °C and a rotation speed of 400 r / min for 1.5 h, and then kept at a temperature of 90 °C for 8 h for pre-plasticization to prepare a substrate.

[0069] (2) The substrate was extruded and granulated using a twin-screw extruder at a temperature of 140°C to prepare a vacuum bag blow molding material.

[0070] The vacuum bag blow molding materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were made into vacuum bags of the same specification, and the weather resistance and anti-aging performance were tested. The specific steps and characterization results are as follows.

[0071] Weather resistance test: The prepared vacuum bags were placed outdoors and exposed to the natural environment, and their appearance changes, hardness changes, and whether cracks were generated were observed and recorded regularly. After three months of exposure testing, it was found that the vacuum bag prepared in Example 2 performed best in terms of weather resistance, with no significant changes in appearance, stable hardness, and no cracks, while the vacuum bags prepared in Comparative Examples 1 to 3 all showed obvious signs of aging to varying degrees, such as yellowing, decreased hardness, and cracks.

[0072] Anti-aging performance test: The prepared vacuum bag was placed in an accelerated aging test chamber, the temperature was set to 70 ° C, the humidity was 50%, and ozone gas was continuously introduced for accelerated aging test. After 168 h of testing, it was found that the vacuum bag prepared in Example 2 also performed well in anti-aging performance, and its tensile strength and elongation at break were maintained at a high level, while the vacuum bags prepared in Comparative Examples 1 to 3 showed a decrease in tensile strength and a shortened elongation at break, indicating that their anti-aging performance was poor.

[0073] Comprehensive analysis of the above test data shows that the vacuum bags prepared in Comparative Examples 1 to 3 are not ideal in terms of weather resistance and anti-aging performance. In the weather resistance test, after three months of outdoor exposure test, the vacuum bag showed obvious color changes in appearance, the hardness decreased, and cracks appeared. In the anti-aging performance test, after 168 hours of accelerated aging test, the tensile strength of the vacuum bag was significantly reduced, and the elongation at break was also significantly shortened, showing poor anti-aging performance. These results show that the vacuum bags prepared in the comparative examples are easily affected by environmental factors during long-term use, resulting in performance degradation, thereby limiting their reliability in practical applications.

Claims

1. A method for preparing a vacuum bag blow molding material, characterized in that: The method comprises: (1) uniformly mixing a polymer compound, a diol, a carboxylic acid and a nano inorganic material in proportion, pre-plasticizing and preparing a substrate; and (2) uniformly mixing a substrate and an organosilicon compound in proportion, melt-extruding and granulating to prepare a vacuum bag blow molding material.

2. The method for preparing a vacuum bag blow molding material according to claim 1, characterized in that: The polymer compound in step (1) is polyvinyl alcohol; the diol in step (1) is ethylene glycol; the carboxylic acid in step (1) is stearic acid; and the nano inorganic material in step (1) is nano zinc oxide.

3. A method for preparing a vacuum bag blow molding material according to claim 1 or 2, characterized in that: In step (1), the polymer compound, diol, carboxylic acid and nano-inorganic material are uniformly mixed in a mass ratio of (15-17): (2-3): (3-5): 1.

5.

4. The method for preparing a vacuum bag blow molding material according to claim 1, characterized in that: The mixing in step (1) is carried out by stirring for 1 to 2 hours at a temperature of 130 to 140°C and a rotation speed of 300 to 500 r / min.

5. The method for preparing a vacuum bag blow molding material according to claim 1 or 4, characterized in that: The pre-plasticization in step (1) is carried out in an environment with a temperature of 80 to 100° C. for 7 to 9 hours.

6. The method for preparing a vacuum bag blow molding material according to claim 1, characterized in that: The organosilicon compound in step (2) is prepared by the following method: trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate are uniformly mixed in a mass ratio of 3:(2-3):1, and concentrated sulfuric acid of 1-2 wt% of the total mass is added in a nitrogen atmosphere at a temperature of 40-50°C, and the reaction is kept warm for 1-2 h, and then anhydrous sodium carbonate is added to neutralize the concentrated sulfuric acid, and hydrochloric acid is used to adjust the pH value to 3-4, and the reaction is kept warm for 1-2 h in an environment of a temperature of 50-70°C, and then 10-20 wt% of the total mass of distilled water is added at an addition rate of 60 mL / min, and the reaction is carried out for 6-8 h to obtain an organosilicon compound.

7. A method for preparing a vacuum bag blow molding material according to claim 1 or 6, characterized in that: In step (2), the substrate and the organosilicon compound are uniformly mixed in a mass ratio of 3:(1-2).

8. The method for preparing a vacuum bag blow molding material according to claim 1, characterized in that: The melt extrusion granulation in step (2) is performed by using a twin-screw extruder at a temperature of 120 to 160°C.

9. A vacuum bag blow molding material obtained by the method according to any one of claims 1 to 8.

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