A vacuum bag blow molding material and a method for manufacturing the same

Abstract

The present application 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, a dihydric alcohol, a carboxylic acid and a nano inorganic material according to a proportion, pre-plasticizing and preparing a base material; and (2) uniformly mixing the base material and an organic silicon compound according to a proportion, melt-extruding and granulating to prepare the vacuum bag blow molding material. The polyvinyl alcohol is modified by a blending melt technology, the modifier with high thermal stability and mechanical properties is selected to improve the heat resistance and strength, the processing and high-temperature resistance are improved by chemical and physical plastic modification, the organic silicon compound is introduced to optimize the microstructure, enhance the connection strength and sealing property, improve the weather resistance and anti-aging property, and enhance the performance and durability of the vacuum bag material. The reaction conditions are accurately controlled during the preparation, a catalyst and nano zinc oxide particles are added to further optimize the material performance and prolong the service life of the vacuum bag.

Description

Technical Field

[0001] This invention belongs to the field of packaging materials technology, specifically relating to a vacuum bag blow molding material and its preparation method. Background Technology

[0002] Vacuum packaging technology plays an irreplaceable role in the food, pharmaceutical, and electronics industries due to its excellent oxygen barrier, moisture protection, and freshness preservation properties. As the core carrier of vacuum packaging, the performance of the vacuum bag material directly determines the reliability and applicability of the packaging. Currently, commercially available vacuum bag materials are mostly based on polyethylene (PE), polypropylene (PP), or polyvinyl chloride (PVC) resins. Although these materials offer certain processing convenience and cost advantages, their inherent defects severely limit the expansion of high-end applications: Insufficient heat resistance: Traditional materials (such as PE) have a low softening point (usually <120℃), making them prone to deformation or thermal decomposition during high-temperature sterilization or heat sealing processes, leading to seal failure; Imbalance between mechanical strength and toughness: While materials such as PVC have high rigidity, they have poor toughness, making them susceptible to damage from external impacts during transportation or storage; and toughened modified materials often suffer from a significant decrease in mechanical properties due to excessive plasticization; Limited barrier properties: PE / PP has poor barrier properties against oxygen and water vapor, making it difficult to meet the long-term protection requirements of high-value-added products (such as precision electronic components and medical devices); Environmental and health risks: PVC processing requires the addition of large amounts of plasticizers (such as phthalates), posing a migration risk and failing to meet the safety requirements for food contact materials.

[0003] To address the aforementioned issues, existing technologies attempt to improve material performance through methods such as blending modification, nanofilling, or surface coating. For example: high-barrier materials: using polyvinylidene chloride (PVDC) or ethylene-vinyl alcohol copolymer (EVOH) to enhance barrier properties, but their high crystallinity leads to stringent processing temperatures and significantly increases costs; heat-resistant modification: introducing inorganic fillers (such as talc) or crosslinking agents to improve thermal stability, but excessive addition can degrade the material's flexibility and transparency; environmentally friendly alternative materials: exploring bio-based materials such as polylactic acid (PLA), but their heat resistance, moisture barrier properties, and mechanical strength still cannot meet the stringent requirements of vacuum bags.

[0004] Furthermore, polyvinyl alcohol (PVA) is considered a potential alternative material due to its high barrier properties, biodegradability, and chemical stability. However, its high crystallinity and strong hydrogen bonding make melt processing difficult. Conventional plasticizing techniques (such as glycerol plasticizing) can lower the processing temperature, but they significantly weaken the material's heat resistance and mechanical strength. In addition, existing technologies that improve the sealing performance of materials through organosilicon modification often suffer from interfacial delamination due to poor compatibility between organosilicon and the substrate, or require expensive chemical grafting processes, making large-scale application difficult.

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

[0006] The present invention addresses the technical problems of insufficient heat resistance, low mechanical strength, and poor sealing performance in traditional solutions by providing a vacuum bag blow molding material and its preparation method.

[0007] The main objective of this invention is:

[0008] I. Improve the heat resistance of materials used in the preparation of vacuum bags;

[0009] II. Enhance the mechanical strength of materials;

[0010] Third, the vacuum bags prepared from the material have excellent sealing performance.

[0011] To achieve the above objectives, the present invention adopts the following technical solution.

[0012] A method for preparing vacuum bag blow molding material,

[0013] The method includes:

[0014] (1) Mix the polymer compound, diol, carboxylic acid and nano-inorganic material in proportion and pre-plasticize to prepare the substrate;

[0015] (2) Mix the substrate and organosilicon compound evenly in proportion, melt extrude and granulate to prepare vacuum bag blow molding material.

[0016] As a preferred option

[0017] The polymer compound mentioned in step (1) is polyvinyl alcohol;

[0018] The diol mentioned in step (1) is ethylene glycol;

[0019] The carboxylic acid mentioned in step (1) is stearic acid;

[0020] The nano-inorganic material mentioned in step (1) is nano-zinc oxide.

[0021] Preferably, the polymer, diol, carboxylic acid and nano-inorganic material in step (1) are mixed evenly at a mass ratio of (15-17):(2-3):(3-5):1.5.

[0022] Preferably, the mixing in step (1) is carried out in an environment with a temperature of 130-140 ℃ and a rotation speed of 300-500 r / min for 1-2 h.

[0023] 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.

[0024] Preferably, the organosilicon compound in step (2) is prepared by the following method:

[0025] Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and ethyl silicate were mixed uniformly in a mass ratio of 3:(2-3):1. Concentrated sulfuric acid (1-2 wt% of total mass) was added under a nitrogen atmosphere at 40-50 °C, and the reaction was maintained at this temperature for 1-2 h. Anhydrous sodium carbonate was then added to neutralize the concentrated sulfuric acid, and the pH was adjusted to 3-4 using hydrochloric acid. The reaction was maintained at 50-70 °C for 1-2 h. Finally, distilled water (10-20 wt% of total mass) was added at a rate of 60 mL / min, and the reaction was continued for 6-8 h to obtain the organosilicon compound.

[0026] Preferably, the substrate and organosilicon compound in step (2) are mixed evenly at a mass ratio of 3:(1-2).

[0027] Preferably, the melt extrusion granulation in step (2) is performed by a twin-screw extruder with a temperature of 120–160 °C.

[0028] A vacuum bag blow molding material.

[0029] The core of this invention lies in modifying polyvinyl alcohol (PVA) using a blending and melting technique to improve its heat resistance and enhance its mechanical strength. During the blending and melting process, a modifier with high thermal stability and good mechanical properties is first selected and uniformly mixed with PVA. This modifier effectively interacts with the PVA molecular chains, maintaining the material's structural stability at high temperatures and preventing performance degradation due to thermal decomposition. Simultaneously, the addition of the modifier also enhances the intermolecular forces within the PVA molecular chains to a certain extent, improving its mechanical strength and resulting in vacuum bag materials exhibiting better toughness and durability under external forces.

[0030] Environmentally friendly materials such as polyvinyl alcohol (PVA) have attracted much attention due to their biodegradability. Although PVA possesses numerous advantages, such as excellent chemical stability, good film-forming properties, and environmental friendliness, its high crystallinity and strong intermolecular hydrogen bonding make processing challenging. To achieve efficient processing, plasticizing modification techniques are necessary to lower its melting temperature and weaken intermolecular forces, thereby improving its processing performance and application range. Currently, plasticizing modification of PVA is mainly achieved through chemical and physical methods. Chemical modification involves introducing new functional groups to improve the molecular structure, thereby enhancing its water resistance, solvent resistance, and corrosion resistance. However, this method suffers from high cost, high toxicity, and difficulty in achieving continuous production. In contrast, physical modification involves adding small molecules or oligomers to break intermolecular hydrogen bonds, altering the material's crystalline state without chemical reactions, offering advantages such as ease of operation, high efficiency, and suitability for industrialization. Among physical modifications, blending modification is the primary form of implementation. In this invention, polyvinyl alcohol (PVA) is plasticized and modified with ethylene glycol, significantly expanding the thermal processing window and facilitating continuous industrial production. This 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 PVA, effectively weakening intermolecular hydrogen bonding forces, lowering the melting temperature and viscosity of PVA, making it easier to flow and shape during processing. Simultaneously, the addition of ethylene glycol does not significantly affect the chemical stability of PVA, ensuring the long-term performance of the material. During the preparation process, the addition ratio of ethylene glycol and processing conditions were optimized to maximize the plasticizing effect. The modified PVA material, while maintaining its original excellent properties, significantly improves its 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.

[0031] Furthermore, another core element of the technical solution of this invention lies in providing a special organosilicon compound. This compound enhances the bonding strength and sealing performance between the components in the material by optimizing the microstructure of the substrate. This organosilicon compound exhibits good compatibility with polyvinyl alcohol and ethylene glycol. During the material preparation process, the organosilicon compound is uniformly dispersed in the polyvinyl alcohol matrix, and its active functional groups react with the hydroxyl groups of polyvinyl alcohol to form stable chemical bonds. This chemical bonding not only enhances the overall strength of the material but also significantly improves its sealing performance, ensuring that the vacuum bag will not leak during use. Simultaneously, the addition of the organosilicon compound also improves the material's weather resistance and anti-aging properties. When exposed to prolonged light, high temperature, or humid environments, the organosilicon compound effectively resists the erosion of material properties by external factors, extending the service life of the vacuum bag.

[0032] This invention relates to an organosilicon compound prepared by copolymerizing trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and ethyl silicate. By precisely controlling the copolymerization ratio of the above monomers, this organosilicon compound exhibits excellent stability, thereby improving the performance of vacuum bag blow molding materials. The use of octamethylcyclotetrasiloxane effectively avoids the formation of active organic groups by hydroxyl condensation under high-temperature conditions, thus preventing adverse effects on the substrate surface and significantly enhancing the material's sealing performance. In particular, the selective use of trifluoropropyltrimethylcyclotrisiloxane modifies the substrate. Utilizing the high electronegativity and low surface tension characteristics of fluorine, fluorine-containing segments aggregate on the outer layer of the substrate, significantly reducing the surface tension of the substrate, and the protective effect of the CF bonds significantly improves the durability of the substrate fabric. Furthermore, the polymerization reaction between nano-zinc oxide particles in the substrate and the organosilicon compound further improves the material's durability and stability, and the uniform distribution of particles also enhances the internal consistency of the material, thereby extending the service life of the vacuum bag.

[0033] In the preparation process, trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and ethyl silicate are first mixed in a certain proportion and copolymerized under inert gas protection. By adjusting the reaction temperature and reaction time, the copolymerization process can be precisely controlled, thereby obtaining organosilicon compounds with specific properties. Furthermore, adding an appropriate amount of catalyst to the reaction system can further improve the reaction rate and product purity. In the obtained organosilicon compounds, the fluorine element of trifluoropropyltrimethylcyclotrisiloxane forms stable chemical bonds with the hydrogen element in the matrix, which not only improves the heat resistance of the material but also endows it with excellent anti-aging properties. Simultaneously, the introduction of octamethylcyclotetrasiloxane allows the material to maintain a stable structure at high temperatures, avoiding performance degradation caused by hydroxyl condensation. To further optimize the material's performance, an appropriate amount of nano-zinc oxide particles can be added during the preparation process. These particles can undergo polymerization with the organosilicon compounds to form a denser network structure, thereby improving the material's strength and toughness. In addition, the uniform distribution of nano zinc oxide particles can effectively prevent cracks and damage during use, further extending the service life of vacuum bags.

[0034] The advantages of this invention are as follows: This invention modifies polyvinyl alcohol (PVA) using a blending and melting technique, selecting modifiers with high thermal stability and mechanical properties to improve heat resistance and strength. PVA is plasticized and modified through chemical and physical methods, primarily through blending, with ethylene glycol acting as a plasticizer to improve processing and high-temperature resistance. The introduction of organosilicon compounds optimizes the microstructure, enhances bonding strength and sealing performance, and improves weather resistance and anti-aging properties. Organosilicon is prepared through specific compounds, enhancing the performance and durability of the vacuum bag material. Precise control of reaction conditions during preparation, along with the addition of catalysts and nano-zinc oxide particles, further optimizes material properties and extends the service life of the vacuum bags. Detailed Implementation

[0035] The present invention will be further described clearly and in detail below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0036] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0037] Example 1: A method for preparing a vacuum bag blow molding material.

[0038] The method includes:

[0039] (1) Polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide were mixed evenly in a mass ratio of 15:2:3:1.5 and stirred for 2 h at a temperature of 130 ℃ and a speed of 300 r / min. Then, the mixture was kept at a temperature of 80 ℃ for 9 h for pre-plasticization to prepare the substrate.

[0040] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were mixed evenly in a mass ratio of 3:2:1. Concentrated sulfuric acid of 1 wt% of total mass was added in a nitrogen atmosphere at a temperature of 40 °C and the reaction was kept at the temperature for 2 h. Then anhydrous sodium carbonate was added to neutralize the concentrated sulfuric acid, and the pH value was adjusted to 3 with hydrochloric acid. The reaction was kept at the temperature of 50 °C for 2 h. Then distilled water of 10 wt% of total mass was added at an addition rate of 60 mL / min and the reaction was kept at the temperature for 8 h to obtain organosilicon compounds.

[0041] (3) Mix the substrate and organosilicon compound evenly at a mass ratio of 3:1, and extrude and granulate using a twin-screw extruder at a temperature of 120 ℃ to prepare vacuum bag blow molding material.

[0042] The blow-molded material prepared in this example was subjected to performance testing, and the specific characterization results are as follows.

[0043] Mechanical property testing: The material prepared in this example was cut into standard dumbbell-shaped small strips, and tensile strength and elongation at break were tested using an electronic universal testing machine according to the national standard GB / T1040.3-2006. The speed was set to 100 mm / min, and 5 strips were tested in each group. The final result was the average value.

[0044] Oxygen permeability testing: Using a thin film sampler with uniform thickness and no quality issues, test samples with a diameter of 97 mm were cut. The oxygen permeability of the film was tested using a differential pressure gas permeameter according to GB / T1038-2000. The performance test was carried out in an environment with a temperature of 23 ℃ and a humidity of 50 %RH. Each test sample was tested 5 times, and the final result was the average value.

[0045] Barrier test: The material prepared in this example was made 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 for 1 day in an environment with a temperature of 25 ℃. The excess edible oil on the surface was removed 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 the average value.

[0046]

[0047] In the formula:

[0048] —Material oil absorption rate, %

[0049] —Weight after oil immersion, mg;

[0050] —Initial mass of the sample, mg.

[0051] Thermogravimetric analysis: Under a nitrogen atmosphere, at a temperature of 25 °C and a heating rate of 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.

[0052] Table 1: Characterization results of Example 1:

[0053] Analysis of the above characterization results reveals that the vacuum bag blow molding material prepared in this invention exhibits excellent performance in terms of sealing, thermal stability, and mechanical properties. Specifically, the oxygen permeability of this material is 27.78 cm⁻¹. 3 / (m 2 The material exhibits excellent sealing properties (·d·0.1MPa). Furthermore, its mechanical properties are also outstanding, with tensile strength and elongation at break reaching 54.64 MPa and 831.7%, respectively, demonstrating high strength and toughness to meet the needs of various applications. In summary, the vacuum bag blow molding material of this invention possesses excellent comprehensive performance and is expected to be widely used in food packaging, medical devices, and other fields. Meanwhile, during in-depth analysis of the material's thermal stability, a significant phenomenon was observed: as the temperature gradually increases, the mass of the test sample shows a clear downward trend. This thermal decomposition process can be meticulously divided into three distinct stages. First, in the first stage, when the temperature range increases from 270 ℃ to 470 ℃, the breaking of carbon-silicon bonds was observed, directly leading to the decomposition of small molecule polymers. Then, in the second stage, when the temperature range increases from 470 ℃ to 600 ℃, the breaking of silicon-oxygen bonds becomes dominant, a process accompanied by a significant loss of mass. Finally, in the third stage, when the temperature range increased from 600 ℃ to 800 ℃, the decomposition rate slowed down. This stage mainly involved the decomposition of the residual carbonaceous portion. A comprehensive evaluation of the thermogravimetric analysis results leads to the conclusion that the prepared material exhibits quite good thermal stability.

[0054] Example 2: A method for preparing a vacuum bag blow molding material.

[0055] The method includes:

[0056] (1) Polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide were mixed evenly in a mass ratio of 16:2.5:4:1.5 and stirred for 1.5 h at a temperature of 135 ℃ and a speed of 400 r / min. Then, the mixture was kept at a temperature of 90 ℃ for 8 h for pre-plasticization to prepare the substrate.

[0057] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were mixed evenly in a mass ratio of 3:2.5:1. 1.5 wt% of concentrated sulfuric acid was added in a nitrogen atmosphere at a temperature of 45 ℃ and the reaction was kept at the temperature for 1.5 h. Then anhydrous sodium carbonate was added to neutralize the concentrated sulfuric acid and the pH value was adjusted to 3.5 with hydrochloric acid. The reaction was kept at the temperature of 60 ℃ for 1.5 h. Then 15 wt% of distilled water was added at a rate of 60 mL / min and the reaction was kept at the temperature for 7 h to obtain organosilicon compounds.

[0058] (3) Mix the substrate and organosilicon compound evenly at a mass ratio of 2:1, and extrude and granulate using a twin-screw extruder at a temperature of 140 ℃ to prepare vacuum bag blow molding material.

[0059] The blow-molded material prepared in this example was subjected to performance testing. The specific characterization results are shown in Table 2.

[0060] Table 2: Characterization results of Example 2:

[0061] Example 3: A method for preparing a vacuum bag blow molding material.

[0062] The method includes:

[0063] (1) Polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide are mixed evenly in a mass ratio of 17:3:5:1.5, stirred for 1 h at a temperature of 140 ℃ and a speed of 500 r / min, and then pre-plasticized by keeping warm at a temperature of 100 ℃ for 7 h to prepare the substrate.

[0064] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were mixed evenly in a mass ratio of 3:3:1. Concentrated sulfuric acid of 2 wt% of total mass was added in a nitrogen atmosphere at a temperature of 50 °C and the reaction was kept at the temperature for 1 h. Then anhydrous sodium carbonate was added to neutralize the concentrated sulfuric acid, and the pH value was adjusted to 4 with hydrochloric acid. The reaction was kept at the temperature of 70 °C for 1 h. Then distilled water of 20 wt% of total mass was added at an addition rate of 60 mL / min and the reaction was carried out for 6 h to obtain organosilicon compounds.

[0065] (3) Mix the substrate and organosilicon compound evenly at a mass ratio of 3:2, and extrude and granulate using a twin-screw extruder at a temperature of 160 ℃ to prepare vacuum bag blow molding material.

[0066] The blow-molded material prepared in this example was subjected to performance testing. The specific characterization results are shown in Table 3.

[0067] Table 3: Characterization results of Example 3:

[0068] Comparative Example 1: A method for preparing a vacuum bag blow molding material, the specific preparation method is the same as in Example 2. The comparative example only modifies the substrate components in this invention. The specific characterization results and operation process are as follows.

[0069] (1) Polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide were mixed evenly in a mass ratio of 16:5:4:1.5 and stirred for 1.5 h at a temperature of 135 ℃ and a speed of 400 r / min. Then, the mixture was kept at a temperature of 90 ℃ for 8 h for pre-plasticization to prepare the substrate.

[0070] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were mixed evenly in a mass ratio of 3:2.5:1. 1.5 wt% of concentrated sulfuric acid was added in a nitrogen atmosphere at a temperature of 45 ℃ and the reaction was kept at the temperature for 1.5 h. Then anhydrous sodium carbonate was added to neutralize the concentrated sulfuric acid and the pH value was adjusted to 3.5 with hydrochloric acid. The reaction was kept at the temperature of 60 ℃ for 1.5 h. Then 15 wt% of distilled water was added at a rate of 60 mL / min and the reaction was kept at the temperature for 7 h to obtain organosilicon compounds.

[0071] (3) Mix the substrate and organosilicon compound evenly at a mass ratio of 2:1, and extrude and granulate using a twin-screw extruder at a temperature of 140 ℃ to prepare vacuum bag blow molding material.

[0072] The blow-molded material prepared in this example was subjected to performance testing. The specific characterization results are shown in Table 4.

[0073] Table 4: Characterization results of Comparative Example 1:

[0074] Analysis of the characterization results revealed a significant difference in sealing performance between the vacuum bag blown material prepared in this example and that of Example 2. Further analysis showed that excessive ethylene glycol was present between the PVA matrix molecular chains. While this provided some lubrication, it also enhanced the mobility of the PVA molecular chains, widening the intermolecular gaps and significantly increasing oxygen permeability, thus reducing the sealing performance of the vacuum bag. Furthermore, the excessive introduction of ethylene glycol also affected the mechanical properties of the blown material. Due to the interaction between ethylene glycol molecules and the PVA matrix molecular chains, the tensile strength and elongation at break of the material decreased. This decline in mechanical properties further weakened the durability and reliability of the vacuum bag. Therefore, the amount of ethylene glycol added must be strictly controlled during the preparation of vacuum bag blown materials to avoid adverse effects on material properties.

[0075] Comparative Example 2: A method for preparing a vacuum bag blow molding material. The specific preparation method is the same as in Example 2. The comparative example only modifies the substrate components in this invention and does not use stearic acid in the substrate. The specific characterization results and operation process are as follows.

[0076] (1) Polyvinyl alcohol, ethylene glycol and nano zinc oxide were mixed evenly in a mass ratio of 16:2.5:1.5 and stirred for 1.5 h at a temperature of 135 ℃ and a speed of 400 r / min. Then, the mixture was kept at a temperature of 90 ℃ for 8 h for pre-plasticization to prepare the substrate.

[0077] (2) Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane and ethyl silicate were mixed evenly in a mass ratio of 3:2.5:1. 1.5 wt% of concentrated sulfuric acid was added in a nitrogen atmosphere at a temperature of 45 ℃ and the reaction was kept at the temperature for 1.5 h. Then anhydrous sodium carbonate was added to neutralize the concentrated sulfuric acid and the pH value was adjusted to 3.5 with hydrochloric acid. The reaction was kept at the temperature of 60 ℃ for 1.5 h. Then 15 wt% of distilled water was added at a rate of 60 mL / min and the reaction was kept at the temperature for 7 h to obtain organosilicon compounds.

[0078] (3) Mix the substrate and organosilicon compound evenly at a mass ratio of 2:1, and extrude and granulate using a twin-screw extruder at a temperature of 140 ℃ to prepare vacuum bag blow molding material.

[0079] The blow-molded material prepared in this example was subjected to performance testing. The specific characterization results are shown in Table 5.

[0080] Table 5: Characterization results of Comparative Example 2:

[0081] Analysis of the characterization results revealed significant performance differences between the vacuum bag blow molding material prepared in this example and that of Example 2. Specifically, in the comparative example without the addition of stearic acid, the organosilicon compound exhibited excessive modification of the substrate, leading to a decrease in key indicators such as the mechanical properties, heat resistance, and oil absorption rate of the blow molding material. In contrast, Example 2, by adding an appropriate amount of stearic acid, effectively controlled the degree of modification of the substrate by the organosilicon compound, thereby preparing a vacuum bag blow molding material with superior overall performance.

[0082] Comparative Example 3: A method for preparing a vacuum bag blow molding material. The specific preparation method is the same as in Example 2. The only difference in the comparative example is that the organosilicon compound unique to this invention is not prepared or used. The specific characterization results and operation process are as follows.

[0083] (1) Polyvinyl alcohol, ethylene glycol, stearic acid and nano zinc oxide were mixed evenly in a mass ratio of 16:2.5:4:1.5 and stirred for 1.5 h at a temperature of 135 ℃ and a speed of 400 r / min. Then, the mixture was kept at a temperature of 90 ℃ for 8 h for pre-plasticization to prepare the substrate.

[0084] (2) Use a twin-screw extruder at a temperature of 140 °C to extrude and granulate the substrate to prepare vacuum bag blow molding material.

[0085] Vacuum bag blow molding materials prepared in Examples 1-3 and Comparative Examples 1-3 were made into vacuum bags of the same specifications, and their weather resistance and anti-aging properties were tested. The specific steps and characterization results are as follows.

[0086] Weather resistance test: The prepared vacuum bags were placed outdoors and exposed to the natural environment. Changes in appearance, hardness, and the presence of cracks were observed and recorded periodically. After three months of exposure testing, the vacuum bag prepared in Example 2 showed the best weather resistance, with no significant changes in appearance, stable hardness, and no cracks. In contrast, the vacuum bags prepared in Comparative Examples 1-3 all showed obvious signs of aging to varying degrees, such as yellowing, decreased hardness, and crack formation.

[0087] Anti-aging performance testing: The prepared vacuum bags were placed in an accelerated aging test chamber, with the temperature set at 70 ℃ and the humidity at 50%, and ozone gas was continuously introduced for accelerated aging testing. After 168 hours of testing, it was found that the vacuum bags prepared in Example 2 also showed excellent anti-aging performance, with their tensile strength and elongation at break remaining at a high level. In contrast, the vacuum bags prepared in Comparative Examples 1-3 showed a decrease in tensile strength and a shortening of elongation at break, indicating that their anti-aging performance was poor.

[0088] A comprehensive analysis of the above test data shows that the vacuum bags prepared in Comparative Examples 1-3 did not perform well in terms of weather resistance and anti-aging properties. In the weather resistance test, after three months of outdoor exposure, the vacuum bags exhibited significant color changes, decreased hardness, and cracks. In the anti-aging property test, after 168 hours of accelerated aging, the tensile strength of the vacuum bags decreased significantly, and the elongation at break also shortened considerably, demonstrating poor anti-aging performance. These results indicate that the vacuum bags prepared in the comparative examples are susceptible to environmental factors during long-term use, leading to performance degradation and limiting their reliability in practical applications.

Claims

1. A method for preparing a vacuum bag blow molding material, characterized in that, The method includes: (1) Mix the polymer compound, diol, carboxylic acid and nano-inorganic material in proportion and pre-plasticize to prepare the substrate; (2) Mix the substrate and organosilicon compound evenly in proportion, melt extrude and granulate to prepare vacuum bag blow molding material; The polymer compound mentioned in step (1) is polyvinyl alcohol; The diol mentioned in step (1) is ethylene glycol; The carboxylic acid mentioned in step (1) is stearic acid; The nano-inorganic material mentioned in step (1) is nano-zinc oxide; The polymer, diol, carboxylic acid and nano-inorganic material in step (1) are mixed evenly at a mass ratio of (15-17):(2-3):(3-5):1.5; The organosilicon compound in step (2) is prepared by the following method: Trifluoropropyltrimethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and ethyl silicate were mixed uniformly in a mass ratio of 3:(2-3):

1. Concentrated sulfuric acid of 1-2 wt% of the total mass was added under a nitrogen atmosphere at a temperature of 40-50 °C, and the reaction was maintained at this temperature for 1-2 h. Subsequently, anhydrous sodium carbonate was added to neutralize the concentrated sulfuric acid, and the pH value was adjusted to 3-4 using hydrochloric acid. The reaction was maintained at a temperature of 50-70 °C for 1-2 h. Then, distilled water of 10-20 wt% of the total mass was added at a rate of 60 mL / min, and the reaction was carried out for 6-8 h to obtain organosilicon compounds. In step (2), the substrate and the organosilicon compound are mixed evenly at a mass ratio of 3:(1-2).

2. The method for preparing a vacuum bag blow molding material according to claim 1, characterized in that, In step (1), the mixture is stirred for 1 to 2 hours at a temperature of 130 to 140 ℃ and a rotation speed of 300 to 500 r / min.

3. A method for preparing a vacuum bag blow molding material according to claim 1 or 2, characterized in that, The pre-plasticization process in step (1) involves maintaining the temperature at 80–100 °C for 7–9 h.

4. 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 with a temperature of 120-160 ℃.

5. A vacuum bag blow molding material prepared by any one of claims 1 to 4.

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