Moisture-proof and moisture-absorbing material capable of being injection molded and preparation method thereof

Abstract

The application discloses a kind of injection-moldable moisture-proof moisture-absorbing materials and preparation method thereof, it is related to moisture-absorbing material technical field, the injection-moldable moisture-proof moisture-absorbing material is by the following raw materials according to mass percentage: molecular sieve 50-65% with particle size of 200-300 mesh, silane coupling agent 5-10%, polypropylene 24-44%, glycerol 1-2%;The molecular sieve of the application is moisture-absorbing base material, provides moisture-absorbing capacity for the whole material, polypropylene is flowability carrier, that is, it guarantees the flowability and injection-moldability of material whole, simultaneously as the carrier of molecular sieve, make molecular sieve evenly distribute in it, silane coupling agent is the communication bridge of molecular sieve and polypropylene, so that molecular sieve can be better dispersed in polypropylene carrier, simultaneously can promote molecular sieve and polypropylene better combination, make its structure stable and have enough strength, so that the material can be in the case of having moisture-absorbing function, adapt to the injection molding demand of complex structure spare part, satisfy the product design and production requirement of diversification.

Description

Technical Field

[0001] This invention belongs to the field of moisture-absorbing materials technology, specifically relating to an injection-molded moisture-proof and moisture-absorbing material and its preparation method. Background Technology

[0002] In many fields such as electronics, precision instruments, packaging and transportation, and building materials, the control of environmental humidity is directly related to the performance stability, service life and storage safety of products. Therefore, the application of moisture-proof and hygroscopic materials is of irreplaceable importance.

[0003] Currently, the most widely used moisture-absorbing materials on the market are calcium-based materials. Their core function is to absorb moisture through a chemical reaction between calcium ions and water molecules. To ensure a certain moisture absorption effect, these calcium-based materials require the addition of a large amount of calcium to the formula. However, since the moisture absorption process is essentially a chemical reaction, the combination of water molecules and calcium ions is accompanied by heat release, which may affect surrounding heat-sensitive products. At the same time, the structural stability of the material decreases significantly after moisture absorption, easily producing calcium precipitates and resulting in pulverization. These precipitates and pulverized particles are toxic, which not only pollutes the environment but may also endanger human health and the safety of related products. In addition, calcium-based materials have insufficient fluidity due to their high calcium content, requiring extremely high temperatures for injection molding, which increases production energy consumption and process difficulty. At the same time, even at high temperatures, these materials are difficult to adapt to the injection molding needs of complex parts and cannot meet the diverse product design and production requirements.

[0004] To address these issues, we propose an injection-moldable moisture-proof and hygroscopic material and its preparation method. This material, while possessing moisture-absorbing properties, can be adapted to the injection molding requirements of complex parts, thus meeting diverse product design and production needs. Summary of the Invention

[0005] The purpose of this invention is to provide an injection-molded moisture-proof and hygroscopic material and its preparation method, which can adapt to the injection molding needs of complex parts while having moisture-absorbing function, meet the diverse product design and production requirements, and solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A moldable moisture-proof and absorbent material, by mass percentage, is composed of the following raw materials: 50-65% molecular sieve with a particle size of 200-300 mesh, 5-10% silane coupling agent, 24-44% polypropylene, and 1-2% glycerol.

[0007] Preferably, by mass percentage, it is composed of the following raw materials: 57.5% molecular sieve with a particle size of 200-300 mesh, 7% silane coupling agent, 34% polypropylene, and 1.5% glycerol.

[0008] Preferably, the molecular sieve needs to be graded and dry purified before use in order to select molecular sieves with uniform microporous structure.

[0009] Preferably, the silane coupling agent is a vinyl silane coupling agent. The vinyl group of the vinyl silane coupling agent can chemically react or physically entangle with the olefin chain of polypropylene. After the other end of the vinyl silane coupling agent is digested, a silanol group is generated to form a covalent bond with the hydroxyl group on the surface of the molecular sieve.

[0010] Preferably, the polypropylene is a high-flow homopolymer polypropylene with a melt flow rate of 24±2 g / 10 min and a density of 0.9-0.91 g / cm³. 3 Tensile strength ≥28MPa.

[0011] Preferably, the glycerol is glycerol with a purity of 99.7%, which is used to assist the silane coupling agent in its function and improve the processability and shapeability of the molecular sieve.

[0012] Based on the above description of an injection-moldable moisture-proof and wicking material, this invention also provides a method for preparing the injection-moldable moisture-proof and wicking material, comprising the following steps: S1. Weigh the raw materials of molecular sieve, silane coupling agent, polypropylene and glycerol by mass percentage; S2. Place the weighed raw materials into a high-speed mixer for premixing to obtain a premix; S3. The premixed material is conveyed to the twin-screw extruder through a vacuum feeding device for continuous linear material extrusion. S4. After cooling the continuous linear material through a vacuum air-cooling system, it is granulated to obtain injection-molded moisture-proof and hygroscopic material granules.

[0013] Preferably, in step S2, the mixing speed of the high-speed mixer is 60-80 r / min, and the mixing time is greater than 15 minutes.

[0014] Preferably, in step S3, the twin-screw extruder includes a feeding section, a melting section, and a die head section. The temperature of the feeding section is 180-200℃, the temperature of the melting section is 210-230℃, and the temperature of the die head section is 220-230℃.

[0015] Preferably, in step S4, the wind speed of the vacuum air cooling system is 8-12 m / s, the cooling time of the continuous linear material is 3-5 min, and the material temperature drops to below 40°C after cooling before pelletizing. The resulting injection-molded moisture-proof and hygroscopic material granules can be made into injection molded parts through an injection molding mold.

[0016] The present invention provides an injection-molded moisture-proof and hygroscopic material and its preparation method, which have the following advantages compared with the prior art: 1. This invention utilizes the synergistic combination of molecular sieves, silane coupling agents, polypropylene, and glycerol. The molecular sieve serves as a hygroscopic base material, providing moisture absorption capacity for the entire material. Polypropylene acts as a flow carrier, ensuring the overall flowability and injection molding properties of the material. Simultaneously, it serves as a carrier for the molecular sieve, ensuring its uniform distribution. The silane coupling agent acts as a bridge between the molecular sieve and polypropylene, allowing the molecular sieve to be better dispersed within the polypropylene carrier. It also promotes better bonding between the molecular sieve and polypropylene, resulting in a stable structure and sufficient strength. This allows the material to adapt to the injection molding requirements of complex parts while maintaining its moisture absorption function, thus meeting diverse product design and production requirements. 2. This invention involves heating and melting molecular sieves, silane coupling agents, polypropylene, and glycerin using a twin-screw extruder before extrusion. The twin-screw ensures more uniform mixing of the components. After extrusion, the materials must be cooled by air cooling before pelletizing. The materials have strong injection molding properties and can meet the injection molding requirements of complex structural parts. The molded materials have high strength and good density, and the shape and structure can be flexibly designed according to customer needs, thus broadening the application scenarios of moisture-absorbing materials. Attached Figure Description

[0017] Figure 1 A flowchart illustrating the preparation process of an injection-moldeable moisture-proof and hygroscopic material according to an embodiment of the present invention is shown. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 This invention provides an injection-molded moisture-proof and hygroscopic material, which, by mass percentage, consists of 50% molecular sieve with a particle size of 200-300 mesh, 5% silane coupling agent, 44% polypropylene, and 1% glycerol; The molecular sieves need to be graded and dry purified before use in order to select molecular sieves with uniform microporous structures. Specifically, the original molecular sieve is placed in an oven at 120-150℃ and dried for 2-3 hours to remove surface adsorbed moisture, prevent particles from clumping and sticking together, and ensure smooth screening. If there are large agglomerates in the molecular sieve, they are first crushed by a high-speed pulverizer. After crushing, the particle size of the material is controlled below 100 mesh to avoid clogging the screen. Next, pour the pretreated molecular sieve into the upper layer of the vibrating screen. Select a 100-mesh screen, turn on the vibrating screen to remove coarse particles larger than 150μm, collect the material from the lower layer, and then replace it with a 200-mesh screen as the upper screen. Pour the material after coarse screening into the upper 200-mesh screen, keep the vibration parameters stable, and the screening time is 15-20 minutes. During this period, you can gently tap the screen frame to assist separation and avoid material clogging the screen holes. The particles trapped by the 200-mesh screen are returned to the pre-crushing process for reprocessing, and the particles trapped by the 300-mesh screen are the molecular sieves of the target particle size, which are collected for later use. Finally, the material collected by the 300-mesh sieve is passed into the air classifier, the wind speed is adjusted to 8-12m / s, fine powder with a particle size of less than 53μm is removed, and finally 200-300 mesh molecular sieve with a purity of ≥98% is obtained. The silane coupling agent is a vinyl silane coupling agent, such as ZQ172. The vinyl group of the vinyl silane coupling agent can chemically react or physically entangle with the olefin chain of polypropylene. After the other end of the vinyl silane coupling agent is decomposed, a silanol group is generated to form a covalent bond with the hydroxyl group on the surface of the molecular sieve, thereby improving the dispersibility and bonding strength of the filler in the matrix and meeting the needs of molecular sieve and polypropylene composite. ZQ172 is prepared from vinyltrichlorosilane and β-methoxyethanol as raw materials through esterification reaction, deacidification and purification process. Specifically, vinyltrichlorosilane is purified first, β-methoxyethanol is dried, and the raw materials are prepared in a molar ratio of 1:3.1-3.3. Excess β-methoxyethanol is used to inhibit multi-step hydrolysis. Then, β-methoxyethanol was added to a reaction vessel equipped with stirring, condensation, and tail gas absorption. The mixture was cooled to 10-15°C, and vinyltrichlorosilane was slowly added dropwise, with the temperature controlled to not exceed 30°C during the addition. The reaction produced the target product and HCl gas. After the reaction was complete, the temperature was raised to 60-80°C, and the vacuum degree was -0.08 to -0.09 MPa. Excess β-methoxyethanol was removed by distillation. Subsequently, the temperature was raised to 120-150°C, and vacuum distillation was performed to achieve a vacuum degree above -0.095 MPa. The fraction collected at 280-285°C yielded ZQ172 product with a purity ≥98%. The polypropylene is a high-flow homopolymer polypropylene, specifically Formosa Plastics PP1024 polypropylene, with a melt flow rate of 24±2 g / 10 min and a density of 0.9-0.91 g / cm³. 3With a tensile strength ≥28MPa, it has excellent fluidity, processing stability and mechanical strength. Its chemical nature is propylene monomer, which is a linear polymer formed by coordination polymerization. The molecular chain is mainly isotactic, which has both rigidity and toughness. It is the core material of fluid carrier. Formosa Plastics' PP1024 polypropylene uses a propylene gas-phase polymerization process, with propylene as the monomer and Ziegler-Natta as the catalyst. Specifically, the propylene monomer is desulfurized, dehydrated, and deoxidized to remove carbon monoxide and carbon dioxide to ensure a purity of ≥99.95%. The catalyst system consists of a main catalyst, a co-catalyst, and an external electron donor, such as dicyclopentyldimethoxysilane. The main catalyst is a TiCl4 / MgCl2 supported type, and the co-catalyst is triethylaluminum. Then, the refined propylene and the activated catalyst are introduced into the gas phase polymerization reactor. The reaction temperature is controlled at 70-85℃ and the pressure at 2.0-3.0MPa. Under the action of the catalyst, the propylene undergoes coordination polymerization, and the molecular chains grow in an isotactic manner to generate polypropylene powder. By controlling the amount of catalyst and the reaction time, the polymer molecular weight and melt flow rate are adjusted. The melt flow rate needs to be precisely controlled at about 24g / 10min. After polymerization, the powder is degassed to remove unreacted propylene. Antioxidants and slip agents are added, and the powder is melted and mixed in a twin-screw extruder at a temperature of 180-220℃. After water cooling and pelletizing or air cooling, large particles and fine powder are removed by sieving. The melt flow rate, mechanical properties and appearance are tested, and the qualified powder is packaged. The glycerol is 99.7% pure glycerol, used to assist the silane coupling agent in its function and improve the processability and shapeability of the molecular sieve; wherein, the 99.7% pure glycerol is prepared from propylene using the acrolein method. Specifically, propylene with a purity ≥99.5% is mixed with air at a volume ratio of 1:6-8, preheated to 300-350℃, and then introduced into a fixed-bed reactor filled with a molybdenum-bismuth composite catalyst (Mo-Bi-Fe-Co-O / SiO2) to undergo an oxidation reaction. The reaction temperature is controlled at 320-380℃ and the pressure is 0.1-0.2MPa. The propylene conversion rate is ≥95%, and the acrolein selectivity is ≥88%. The product is condensed and distilled to obtain acrolein with a purity ≥98%. Acrolein and deionized water are then mixed at a mass ratio of 1:5-8, and an acidic catalyst, such as cation exchange resin or phosphoric acid, is added. The mixture undergoes a hydration reaction in a reactor at 60-80℃ and 0.3-0.5MPa for 1-2 hours. The acrolein conversion rate is ≥90%, and the 3-hydroxypropanal selectivity is ≥92%. Excess water is removed by vacuum distillation to obtain a concentrated 3-hydroxypropanal solution. The concentrated 3-hydroxypropionaldehyde solution is then mixed with hydrogen at a molar ratio of 1:3-5, and Raney nickel catalyst or Cu-Zn-Al catalyst is added. The mixture is then hydrogenated in a high-pressure reactor at 100-140℃ and 3.0-5.0MPa to produce crude glycerol with a concentration of 80%-85%. Finally, the crude glycerol undergoes multi-step distillation. First, low-boiling-point impurities, such as methanol and acetaldehyde, are removed by atmospheric distillation. Then, the glycerol fraction is collected by vacuum distillation under vacuum conditions of -0.095 MPa and 180-200℃. Finally, the product is dehydrated by ion exchange resin and molecular sieve to remove metal ions, yielding a glycerol product with a purity ≥99.7%. After passing tests for moisture, ash, and transmittance, the product is considered to have a purity of 99.7%.

[0020] By using molecular sieves as the hygroscopic base material, the entire material is provided with hygroscopic capacity. Polypropylene serves as the flow carrier, ensuring the overall flowability and injection molding properties of the material. At the same time, it acts as a carrier for the molecular sieves, allowing them to be evenly distributed within the material. Silane coupling agents act as a bridge between the molecular sieves and polypropylene, enabling the molecular sieves to be better dispersed within the polypropylene carrier. This also promotes better bonding between the molecular sieves and polypropylene, resulting in a stable structure and sufficient strength. As a result, this material, while possessing hygroscopic properties, can be adapted to the injection molding requirements of complex parts, meeting diverse product design and production requirements.

[0021] Based on the above description of an injection-moldable moisture-absorbing material, this invention also provides a method for preparing such an injection-moldable moisture-absorbing material, such as... Figure 1 As shown, it includes the following steps: S1. Weigh the raw materials of molecular sieve, silane coupling agent, polypropylene and glycerol by mass percentage; S2. Place the weighed raw materials into a high-speed mixer for premixing to obtain a premix; The high-speed mixer has a mixing speed of 60-80 r / min and a mixing time of more than 15 minutes; S3. The premixed material is conveyed to the twin-screw extruder through a vacuum feeding device for continuous linear material extrusion. The twin-screw extruder includes a feeding section, a melting section, and a die head section. The temperature of the feeding section is 180-200℃, the temperature of the melting section is 210-230℃, and the temperature of the die head section is 220-230℃.

[0022] S4. After cooling the continuous linear material through a vacuum air-cooling system, it is granulated to obtain injection-molded moisture-proof and hygroscopic material granules. The air velocity of the vacuum air cooling system is 8-12 m / s, and the cooling time of the continuous linear material is 3-5 min. After cooling, the material temperature drops to below 40℃ before pelletizing. The resulting injection-molded moisture-proof and hygroscopic material granules can be made into injection molded parts through injection molding.

[0023] Molecular sieves, silane coupling agents, polypropylene, and glycerin are heated and melted through a twin-screw extruder before being extruded. The twin screw ensures more uniform mixing of the components. After extrusion, the material must be cooled by air cooling before pelletizing. It has strong injection molding properties and can meet the injection molding requirements of complex structural parts. The molded material has high strength and good density. The shape and structure can be flexibly designed according to customer needs, which broadens the application scenarios of moisture-absorbing materials. Example 2 The similarities will not be repeated here. The difference from Example 1 is that, by mass percentage, it consists of 57.5% molecular sieve with a particle size of 200-300 mesh, 7% silane coupling agent, 34% polypropylene, and 1.5% glycerol.

[0024] Example 3 The similarities will not be repeated here. The difference from Example 1 is that, by mass percentage, it consists of 65% molecular sieve with a particle size of 200-300 mesh, 10% silane coupling agent, 24% polypropylene, and 2% glycerol.

[0025] Comparative Example 1 (simulating traditional calcium-based moisture-absorbing materials) A moisture-absorbing material, by mass percentage, is composed of 60% calcium oxide, 5% zinc stearate, and 35% polyethylene.

[0026] Comparative Example 2 A moisture-absorbing material, by mass percentage, consists of 50% molecular sieve with a particle size of 200-300 mesh, 49% polypropylene, and 1% glycerol. Comparative Example 3 A moisture-absorbing material, by mass percentage, is composed of 50% molecular sieve with a particle size of 200-300 mesh, 5% silane coupling agent, and 45% polypropylene.

[0027] Comparative Example 4 A moisture-absorbing material, by mass percentage, is composed of 30% molecular sieve with a particle size of 200-300 mesh, 5% silane coupling agent, 63% polypropylene, and 2% glycerol.

[0028] Comparative Example 5 A moisture-absorbing material, by mass percentage, is composed of 50% molecular sieve with a particle size of 200-300 mesh, 5% silane coupling agent, 44% polypropylene, and 1% glycerol.

[0029] The moisture-absorbing materials provided in Examples 1 to 3 and Comparative Examples 1 to 5 were all prepared using the following preparation process, the only difference being the high-speed formulation: 1. Weigh the raw materials according to the proportion, place them in a high-speed mixer, mix at a mixing rate of 60-80 r / min, and premix for 18 min; 2. Vacuum feeding into a twin-screw extruder to extrude linear material, wherein the temperature of the feeding section is 190℃, the temperature of the melting section is 220℃, and the temperature of the die head section is 225℃; 3. Vacuum air cooling, with a wind speed of 10m / s, cooling for 4 minutes to below 35℃, cutting into pellets, and injection molding into standard samples. Tensile test specimens: GB / T1040-2006; Moisture absorption test specimens: 20mm×20mm×5mm; Complex structural parts: specimens with Φ2mm fine holes and grooves.

[0030] The standard samples prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were subjected to performance tests, as detailed below: I. The test content and test methods are shown in Table 1 below: Table 1

[0031] The test results are shown in Table 2 below: Table 2

[0032] III. Based on the data in Table 2, the following conclusions can be drawn: 1. Examples 1-3 have the following advantages compared to the comparative examples: In terms of safety, Examples 1-3 adopt the physical moisture absorption principle of molecular sieves, which achieves moisture absorption function by locking water through pore size. The whole process does not release heat, and the material structure is stable after moisture absorption without pulverization. This completely avoids the heat release caused by chemical reactions in traditional calcium-based materials, namely the moisture absorption and heat release temperature of 15°C, calcium precipitation and serious pulverization problems. It solves the safety hazards of toxicity and harm of traditional materials from the root, making it more environmentally friendly and safer to use. In terms of moisture absorption performance, the saturated moisture absorption rate of the embodiment reaches 12.72%-18.06%, which is much higher than the 8.5% of traditional calcium-based materials; at the same time, the moisture absorption rate is greatly improved, reaching a saturated moisture absorption rate of 50% in only 2.0-2.5 hours, while traditional calcium-based materials require 8 hours. The moisture absorption efficiency of the embodiment is 3-4 times that of traditional materials, and the moisture absorption capacity is increased by 50%-112% compared with traditional materials, resulting in a more efficient moisture-proof and moisture-absorbing effect. In terms of injection moldability, the example uses polypropylene as the flow carrier, and the injection molding qualification rate of complex structural parts is as high as 97%-99%, with a minimum injection temperature of only 210-215℃; while traditional calcium-based materials have insufficient flowability due to high calcium content, and the qualification rate of complex structural parts is only 30%, and injection molding can only be performed at a high temperature of 260℃. The example not only meets the molding requirements of complex parts, but also significantly reduces production energy consumption and process difficulty. In terms of structural stability, the example exhibits a moisture absorption expansion rate of only 0.03%-0.07%, a tensile strength maintained at 28-32 MPa, no significant deformation after moisture absorption, and a dense and robust structure. In contrast, traditional calcium-based materials exhibit a moisture absorption expansion rate of up to 5.2% and a tensile strength of only 15 MPa, which easily leads to volume expansion and loose structure. The example completely solves the defects of traditional materials in terms of deformation and insufficient strength after moisture absorption, resulting in superior stability in use. Therefore, the injection-molded moisture-proof and hygroscopic material of the embodiment surpasses traditional calcium-based materials in terms of safety, moisture absorption efficiency, injection moldability and structural stability, perfectly making up for the core defects of traditional materials, and better meeting the high standard requirements of moisture-proof and hygroscopic materials in the fields of electronics, electrical appliances and precision instruments.

[0033] 2. Compared with Comparative Example 2, Example 1: After the absence of silane coupling agent, the molding qualification rate dropped from 98% to 70%, the tensile strength dropped from 32MPa to 20MPa, and slight powdering (grade 1) occurred. This indicates that silane coupling agent is the bonding bridge between molecular sieve and polypropylene, which can improve the dispersibility of filler and the interfacial bonding force, and ensure the stability of material structure and injection molding. 3. Compared with Comparative Example 3, Example 1 showed that after the absence of glycerol, the saturated moisture absorption rate decreased from 12.72% to 11.5%, and the moisture absorption rate increased from 2.5h to 3.0h. This indicates that glycerol can assist the silane coupling agent in playing its role, while improving the flowability of molecular sieve processing and slightly increasing the moisture absorption efficiency. 4. Comparison of Examples 1-3 and Comparative Example 4: The saturated moisture absorption rate of Comparative Example 4 (30% molecular sieve) is only 7.8%, which is much lower than that of Examples 1-3 (12.72%-18.06%), but the tensile strength is slightly higher (35MPa). This indicates that the molecular sieve is the core of moisture absorption, and the proportion needs to be controlled in the range of 50%-65%. If it is lower than 50%, the moisture absorption capacity is insufficient. If it is higher than 65% (such as Example 3=65%), although the moisture absorption rate is the highest (18.06%), the tensile strength is slightly lower (28MPa). A balance needs to be struck between moisture absorption capacity and structural strength. 5. Compared with Comparative Example 5, the pass rate of complex structural parts in Example 1 decreased from 98% to 65%, and the minimum injection temperature increased from 210℃ to 225℃. This shows that the melt flow rate (24±2g / 10min) of high-flow homopolymer polypropylene (Formosa Plastics PP1024) is suitable for injection molding requirements. Its fluidity and processing stability are better than polyethylene, making it the optimal choice for carrier resin. 6. Comparison of Examples 1-3: Example 3 (65% molecular sieve) saturated moisture absorption rate 18.06% > Example 2 (57.5%) 14.83% > Example 1 (50%) 12.72%, indicating a positive correlation between the molecular sieve ratio and moisture absorption rate; Example 1 tensile strength 32MPa > Example 2 30MPa > Example 3 28MPa, indicating a negative correlation between the molecular sieve ratio and structural strength. Therefore, if high moisture absorption capacity is required for application in humid environments, the formulation of Example 3 (65% molecular sieve) should be preferred; if high structural strength and balanced performance are required for application in precision components, the formulation of Example 1 (50% molecular sieve) should be preferred; Example 2 (57.5% molecular sieve) balances moisture absorption rate (14.83%) and strength (30MPa).

[0034] In summary, the moisture-absorbing material of this invention is composed of molecular sieves, silane coupling agents, polypropylene, and glycerol. It fundamentally solves the four major defects of traditional calcium-based moisture-absorbing materials: unsafety, slow moisture absorption, poor injection molding properties, and easy expansion. Molecular sieves provide core moisture absorption capacity, polypropylene ensures flowability, silane coupling agents enhance structural stability, and glycerol helps optimize processing performance. The formulation ratio can be adjusted according to the application scenario: within the range of 50%-65% molecular sieve, 5%-10% silane coupling agent, 24%-44% polypropylene, and 1%-2% glycerol, a dynamic balance between moisture absorption performance and processing / mechanical properties can be achieved. The material of this embodiment far surpasses traditional materials in terms of safety, moisture absorption efficiency, and injection molding properties. In addition, the material of this embodiment can be made into parts, functional components, or desiccants, offering flexible usage and wide applicability in fields with high requirements for moisture protection and molding, such as electronics, precision instruments, and packaging and transportation.

[0035] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A moldable moisture-proof and hygroscopic material, characterized in that, By mass percentage, it consists of the following raw materials: 50-65% molecular sieve with a particle size of 200-300 mesh, 5-10% silane coupling agent, 24-44% polypropylene, and 1-2% glycerol.

2. The injection-molded moisture-proof and hygroscopic material according to claim 1, characterized in that: By mass percentage, it consists of the following raw materials: 57.5% molecular sieve with a particle size of 200-300 mesh, 7% silane coupling agent, 34% polypropylene, and 1.5% glycerol.

3. The injection-molded moisture-proof and hygroscopic material according to claim 1, characterized in that: Before use, the molecular sieve needs to be graded and dry purified to select molecular sieves with uniform microporous structure.

4. The injection-molded moisture-proof and hygroscopic material according to claim 1, characterized in that: The silane coupling agent is a vinyl-type silane coupling agent. The vinyl group of the vinyl silane coupling agent can chemically react or physically entangle with the olefin chain of polypropylene. After the other end of the vinyl silane coupling agent is digested, a silanol group is generated to form a covalent bond with the hydroxyl group on the surface of the molecular sieve.

5. The injection-molded moisture-proof and hygroscopic material according to claim 1, characterized in that: The polypropylene is a high-flow homopolymer polypropylene with a melt flow rate of 24±2 g / 10 min and a density of 0.9-0.91 g / cm³. 3 Tensile strength ≥28MPa.

6. The injection-molded moisture-proof and hygroscopic material according to claim 5, characterized in that: The glycerol is 99.7% pure glycerol, used to assist the silane coupling agent in its function and improve the processability and shapeability of the molecular sieve.

7. A method for preparing an injection-moldable moisture-proof and hygroscopic material, used to prepare the injection-moldable moisture-proof and hygroscopic material according to any one of claims 1-6, characterized in that: Includes the following steps: S1. Weigh the raw materials of molecular sieve, silane coupling agent, polypropylene and glycerol by mass percentage; S2. Place the weighed raw materials into a high-speed mixer for premixing to obtain a premix; S3. The premixed material is conveyed to the twin-screw extruder through a vacuum feeding device for continuous linear material extrusion. S4. After cooling the continuous linear material through a vacuum air-cooling system, it is granulated to obtain injection-molded moisture-proof and absorbent material granules.

8. The method for preparing an injection-molded moisture-proof and hygroscopic material according to claim 7, characterized in that: In step S2, the mixing speed of the high-speed mixer is 60-80 r / min, and the mixing time is greater than 15 minutes.

9. The method for preparing an injection-molded moisture-proof and hygroscopic material according to claim 8, characterized in that: In step S3, the twin-screw extruder includes a feeding section, a melting section, and a die head section. The temperature of the feeding section is 180-200℃, the temperature of the melting section is 210-230℃, and the temperature of the die head section is 220-230℃.

10. The method for preparing an injection-molded moisture-proof and hygroscopic material according to claim 9, characterized in that: In step S4, the air velocity of the vacuum air cooling system is 8-12 m / s, the cooling time of the continuous linear material is 3-5 min, and the material temperature drops to below 40℃ after cooling before pelletizing. The resulting injection-molded moisture-proof and hygroscopic material granules can be made into injection molded parts through injection molding.

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