Preparation method of high-barrier PE heat-sealing film

Abstract

The invention relates to the technical field of PE (polyethylene) heat-sealing films, in particular to a preparation method of a high-barrier PE heat-sealing film which comprises the following components in parts by mass: 100 parts of low-density polyethylene (LDPE); 5 to 15 parts of hydroxyl-terminated polybutadiene (HTPB); 40 to 60 parts of polyolefin elastomer (POE); and 0.002 parts of an anti-blocking agent oleamide. In the scheme, hydroxyl-terminated polybutadiene (HTPB) and polyolefin elastomer (POE) are compounded for use. Polar hydroxyl in a molecular chain of the HTPB can form hydrogen-bond interaction with oxygen and water molecules, the permeation path of the HTPB is remarkably prolonged, and by matching with uniform dispersion of the HTPB in an LDPE matrix, the oxygen permeability of the film is reduced to 100-150cm < 3 > / m < 2 >. 24h. 0.1 MPa, and the water vapor permeability is reduced to 1.5-2g / m < 2 >. 24h. Meanwhile, by introducing POE and utilizing the excellent elasticity of POE and the good compatibility with PE, the flexibility of the modified film is effectively improved, the tensile elongation at break reaches 350%-450%, and the contradiction that the brittleness is increased when the barrier property is improved in traditional barrier modification is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of PE heat-sealing films, and in particular to a preparation method of a high-barrier PE heat-sealing film. Background Art

[0002] Polyethylene (PE) film, with its excellent flexibility, heat-sealing properties, and low cost, has become a core packaging material for food, pharmaceuticals, electronics, and other fields. It is widely used in scenarios such as fresh food preservation and daily necessities sealing. Low-density polyethylene (LDPE) film, in particular, occupies a significant share of the packaging film market due to its good melt flowability and excellent processing properties. To meet the long-term storage needs of products that are easily oxidized and susceptible to moisture, improving the barrier properties of PE film, especially its oxygen and water vapor barrier properties, has become a hot topic in industry research. Existing technologies mainly improve this through multi-layer composites (such as PE / PA / PE structures), the addition of nano-barrier fillers (such as montmorillonite and graphene), or chemical modification (such as grafting polar monomers).

[0003] However, existing technologies have significant drawbacks: the multi-layer composite process is complex, requiring multiple sets of equipment for coordinated production, significantly increasing costs and prone to interlayer peeling. While adding nanofillers can improve barrier properties, uneven dispersion can lead to a decrease in the film's mechanical properties (such as increased brittleness and reduced elongation at break). Traditional chemical modifiers (such as maleic anhydride grafts) have poor compatibility with PE, making it difficult to improve barrier properties while maintaining good heat-sealing performance and flexibility, limiting the product's applicability. Therefore, developing a simple method for preparing PE heat-sealing films that balances high barrier properties with excellent mechanical properties has become a pressing technical challenge for the industry. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing a high-barrier PE heat-sealing film, thereby solving the technical problems mentioned in the background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A high-barrier PE heat-sealing film comprises the following components in parts by weight:

[0007] 100 parts of low-density polyethylene (LDPE);

[0008] 5-15 parts of hydroxyl-terminated polybutadiene HTPB;

[0009] Polyolefin elastomer POE 40-60 parts;

[0010] 0.002 parts of opening agent oleamide.

[0011] In a possible implementation, the low-density polyethylene has a melt flow rate of 2-4 g / 10 min and a density of 0.915-0.925 g / cm 3 .

[0012] In a possible implementation, the number average molecular weight of the hydroxyl-terminated polybutadiene is 2000-3000, and the hydroxyl value is 0.8-1.2 mmol / g.

[0013] In a possible implementation, the polyolefin elastomer is an ethylene-octene copolymer, has a melt flow rate of 1-3 g / 10 min, and a Shore A hardness of 60-80.

[0014] In a possible implementation, the purity of the opener oleamide is ≥98%, and the melting point is between 72° C. and 76° C.

[0015] In one possible implementation, a method for preparing a high-barrier PE heat-sealing film includes the following steps:

[0016] S1 preparation of hydroxyl-terminated polybutadiene modified low-density polyethylene masterbatch:

[0017] a) Weighing 5-15 parts by mass of hydroxy-terminated polybutadiene and 100 parts of low-density polyethylene;

[0018] b) adding the above raw materials into a high-speed mixer and mixing at a speed of 800-900 r / min and a temperature of 80° C.-90° C. for 15-25 minutes until the hydroxyl-terminated polybutadiene is evenly dispersed on the surface of the low-density polyethylene particles and a mixture without obvious agglomeration is formed;

[0019] c) The obtained mixture was fed into a twin-screw extruder with a length-to-diameter ratio of 40:1, and the temperature was controlled in sections according to the following temperature ranges: section 1 135-145°C, section 2 155-165°C, section 3 165-175°C, section 4 165-175°C, section 5 165-175°C, section 6 160-170°C, section 7 160-170°C, section 8 160-170°C, section 9 155-165°C, and the screw speed was maintained at The material is melted, sheared, and mixed at a speed of 280-350 r / min and extruded from a die. The material is then water-cooled at 20°C to 30°C and air-dried. The pelletizer cuts the material into cylindrical masterbatches with a particle size of 3-4 mm to obtain hydroxyl-terminated polybutadiene-modified low-density polyethylene masterbatches. The masterbatches are then dried in a blast drying oven at 55-65°C for 1.5-2.5 hours and sealed for storage.

[0020] S2 preparation of high barrier PE heat-sealing film:

[0021] a) Weighing 50-100 parts of hydroxyl-terminated polybutadiene-modified low-density polyethylene masterbatch, 40-60 parts of polyolefin elastomer, 100 parts of low-density polyethylene, and 0.002 parts of oleic acid amide as an opening agent, by mass;

[0022] b) adding the above raw materials to a high-speed mixer, setting the speed at 750-850r / min and the temperature at 70°C-80°C and mixing for 10-15 minutes to ensure that the opening agent oleamide can be completely dispersed and no local aggregation occurs;

[0023] c) The mixed material is fed into a single-screw film blowing machine and the temperature is controlled in sections according to the following temperature ranges: section 1 160-170°C, section 2 165-175°C, section 3 165-175°C, section 4 165-177°C, section 5 165-177°C, the screw speed is maintained at 250-300 r / min, the blow-up ratio is controlled between 1.8-2.5, the traction speed is set within the range of 7.5-10.5 m / min, and the air ring cooling temperature is maintained at 15-25°C. After the traction and winding processes, a high-barrier PE heat-sealable film with a thickness of 50 μm ± 2 μm is obtained.

[0024] In one possible implementation, all the raw materials are pretreated before being put into use, that is, the low-density polyethylene and polyolefin elastomer are placed in a vacuum drying oven at 55-65°C for 3.5-4.5 hours, and the terminal hydroxyl polybutadiene is dried in a vacuum drying oven at 35-45°C for 1.5-2.5 hours.

[0025] In one possible implementation, during step S1, the temperature of each section of the twin-screw extruder is adjusted according to the amount of hydroxy-terminated polybutadiene and polyolefin elastomer used. As the amount increases, the temperature of each section shows a gradient upward trend to meet the melting requirements of a high proportion of the modifier.

[0026] In one possible implementation, during step S2, the temperature of each section of the single-screw film blowing machine will also be adjusted according to the amount of terminal hydroxyl polybutadiene and polyolefin elastomer used. As the amount increases, the temperature of each section also shows a gradient increase, thereby ensuring that the material can be evenly plasticized.

[0027] In one possible implementation, the different ratios of HTPB and POE are suitable for different scenarios: low ratio is suitable for rigid packaging, medium ratio is suitable for food preservation, and high ratio is suitable for high-end scenarios such as cosmetics soft packaging and pharmaceutical intermediate packaging.

[0028] Beneficial effects compared with existing technologies:

[0029] 1. In this solution, hydroxyl-terminated polybutadiene (HTPB) is compounded with polyolefin elastomer (POE) to construct a synergistic system of barrier enhancement and flexibility adjustment. The polar hydroxyl groups in the HTPB molecular chain can form hydrogen bonds with oxygen and water molecules, significantly extending their permeation path. Combined with the uniform dispersion of HTPB in the LDPE matrix, the oxygen permeability of the film is reduced to 100-150cm 3 / m 2 24h 0.1MPa, water vapor transmission rate as low as 1.5-2g / m 2 24 hours. Furthermore, the introduction of POE, leveraging its excellent elasticity and good compatibility with PE, effectively improves the flexibility of the modified film, achieving a tensile elongation at break of 350%-450%, resolving the contradiction in traditional barrier modification where improved barrier properties result in increased brittleness. Comparative experiments show that the comprehensive performance of the product of this invention far exceeds that of modified films containing only HTPB or POE, validating the innovative value of synergy.

[0030] 2. This solution uses a two-step process of masterbatch modification and blending film blowing, using conventional twin-screw extruders and single-screw film blowing machines throughout the process, without the need for special equipment or complex procedures. By controlling the mixing temperature, extrusion segment temperature, and screw speed, the uniform dispersion of HTPB and POE in LDPE can be stably achieved, ensuring consistent product performance. Compared to multi-layer composite processes, this method eliminates steps such as interlayer bonding and hot pressing composites; compared to nanofiller modification, it avoids the problems of filler pretreatment and uneven dispersion, significantly improving process stability.

[0031] 3. In this solution, by adjusting the ratio of HTPB (5-15 parts) to POE (40-60 parts), the film's barrier and mechanical properties can be flexibly adjusted, resulting in a series of products tailored to meet the needs of different scenarios. Products with a low HTPB + low POE ratio are suitable for rigid packaging; medium-ratio products offer a balance of barrier and flexibility, suitable for food preservation; and high-ratio products offer optimal barrier properties and excellent flexibility, meeting the needs of high-end packaging such as cosmetics flexible packaging and pharmaceutical intermediates. This further broadens the application boundaries and provides the packaging industry with an innovative solution that offers balanced performance and adaptability to different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings.

[0033] Figure 1 Schematic diagram of the specific process of S1 in the preparation process of the high barrier PE heat-sealing film of the present invention;

[0034] Figure 2Schematic diagram of the specific process of S2 in the preparation process of the high barrier PE heat-sealing film of the present invention. DETAILED DESCRIPTION

[0035] Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention can be implemented in various forms, and therefore the present invention is not limited to the embodiments described below. In addition, in order to more clearly describe the present invention, components that are not related to the present invention will be omitted from the drawings.

[0036] The technical solutions in the embodiments of this application are intended to address the aforementioned background technology issues. The following describes in detail the method for preparing the high-barrier PE heat-sealing film of the present invention through a number of specific examples. The "parts" mentioned in the present invention are all by mass. The raw materials and equipment used are all conventional commercially available products. Unless otherwise specified, the process parameters are controlled according to conventional procedures. The general description is as follows:

[0037] Raw material pretreatment:

[0038] The raw materials used in the present invention must be pretreated before production to remove moisture and impurities in the raw materials to ensure stable product quality:

[0039] Hydroxyl-terminated polybutadiene (HTPB): number average molecular weight 2000-3000, hydroxyl value 0.8-1.2mmol / g;

[0040] Low-density polyethylene (LDPE): melt flow rate 2-4 g / 10 min (test conditions 190°C, 2.16 kg), density 0.915-0.925 g / cm3;

[0041] Polyolefin elastomer (POE): ethylene-octene copolymer, melt flow rate 1-3 g / 10 min (test conditions 190°C, 2.16 kg), Shore A hardness 60-80;

[0042] Opening agent oleamide: purity ≥98%, melting point 72-76℃.

[0043] All raw materials were pretreated before use: LDPE and POE were dried in a vacuum drying oven at 60 °C for 4 h, and HTPB was dried in a vacuum drying oven at 40 °C for 2 h to remove moisture from the raw materials and avoid bubbles during extrusion.

[0044] Example 1: 5 parts of HTPB + 40 parts of POE

[0045] 1. Preparation of HTPB modified LDPE masterbatch

[0046] Raw material weighing: Accurately weigh 5 parts of HTPB and 100 parts of LDPE by mass, and the weighing accuracy should be controlled within ±0.1%.

[0047] Mixing: Add the above raw materials into a high-speed mixer, set the speed to 800r / min, the mixing temperature to 80℃, and the mixing time to 15min, until the HTPB is evenly dispersed on the surface of the LDPE particles to form a mixture without obvious agglomeration.

[0048] Extrusion granulation: The mixture was fed into a twin-screw extruder with an aspect ratio of 40:1. The extrusion temperature was set as follows (unit: °C): 135°C for stage 1, 155°C for stage 2, 165°C for stage 3, 165°C for stage 4, 165°C for stage 5, 165°C for stage 6, 160°C for stage 7, 160°C for stage 8, and 155°C for stage 9. The screw speed was 300 r / min and the feed rate was 50 kg / h. After melting, shearing, and mixing, the material was extruded from the die. After water cooling (water temperature 25°C) and air drying, it was cut into cylindrical masterbatches with a diameter of 3-4 mm using a pelletizer. This is the HTPB-modified LDPE masterbatch. The masterbatch was dried in a forced air drying oven at 60°C for 2 hours and sealed for later use.

[0049] 2. Preparation of high barrier PE heat sealing film

[0050] Raw material weighing: Weigh 50 parts of HTPB modified LDPE masterbatch, 40 parts of POE, 100 parts of LDPE, and 0.002 parts of oleamide according to mass.

[0051] Mixing: Add the raw materials into a high-speed mixer, set the speed to 750r / min, the mixing temperature to 70℃, and the mixing time to 10min to ensure that the oleamide is completely dispersed without local aggregation.

[0052] Film Blowing: The mixed material was fed into a single-screw film blowing machine. The film blowing temperature was set in the following sections (unit: °C): Section 1: 160°C, Section 2: 165°C, Section 3: 165°C, Section 4: 165°C, Section 5: 165°C. The screw speed was 250 r / min, the blow-up ratio was 2.0, the pulling speed was 8 m / min, and the air ring cooling temperature was 20°C. After pulling and winding, a high-barrier PE heat-sealable film with a thickness of 50 μm ± 2 μm was obtained.

[0053] 3. Performance Testing

[0054] The performance of the film was tested according to national standards. The heat seal strength test conditions were: 120°C, 0.2MPa, 1s. The results are as follows:

[0055]

[0056] The heat-sealing film prepared in this embodiment using a low ratio of HTPB and POE has high heat-sealing strength and good rigidity, and is suitable for rigid packaging scenarios with strict sealing requirements, such as moisture-proof packaging of small electronic components.

[0057] Example 2: 10 parts of HTPB + 50 parts of POE

[0058] 1. Preparation of HTPB modified LDPE masterbatch

[0059] Raw material weighing: Weigh 10 parts of HTPB and 100 parts of LDPE.

[0060] Mixing: Add to high-speed mixer, set the speed to 850r / min, mixing temperature to 85℃, mixing time to 20min, and ensure that HTPB and LDPE are fully infiltrated.

[0061] Extrusion granulation: Twin-screw extruder temperature settings (unit: ° C): 140 ° C for section 1, 160 ° C for section 2, 170 ° C for section 3, 170 ° C for section 4, 170 ° C for section 5, 165 ° C for section 6, 165 ° C for section 7, 165 ° C for section 8, and 160 ° C for section 9. Screw speed 320 r / min, feed rate 55 kg / h. The obtained masterbatch was dried for later use.

[0062] 2. Preparation of high barrier PE heat sealing film

[0063] Raw material weighing: weigh 75 parts of HTPB modified LDPE masterbatch, 50 parts of POE, 100 parts of LDPE, and 0.002 parts of oleamide.

[0064] Mixing: High-speed mixer parameters: speed 800r / min, temperature 75℃, time 12min.

[0065] Film blowing: Film blowing temperature settings (unit: °C): 165°C for stage 1, 170°C for stage 2, 170°C for stage 3, 170°C for stage 4, and 170°C for stage 5. Screw speed 280 r / min, blow-up ratio 2.2, pulling speed 9 m / min, producing a heat-sealable film with a thickness of 50 μm ± 2 μm.

[0066] 3. Performance Testing

[0067] The performance of the film was tested according to national standards. The heat seal strength test conditions were: 120°C, 0.2MPa, 1s. The results are as follows:

[0068]

[0069] This embodiment uses a moderate ratio of HTPB and POE, and the barrier performance and flexibility of the film are balanced, which is suitable for most food packaging scenarios (such as baked goods and dairy products) and can effectively extend the shelf life of the product.

[0070] Example 3: 15 parts of HTPB + 60 parts of POE

[0071] 1. Preparation of HTPB modified LDPE masterbatch

[0072] Raw material weighing: weigh 15 parts of HTPB and 100 parts of LDPE.

[0073] Mixing: High-speed mixer parameters: speed 900r / min, temperature 90℃, time 25min, to ensure high proportion of HTPB is evenly dispersed.

[0074] Extrusion granulation: Twin-screw extruder temperature settings (unit: ° C): 145 ° C for section 1, 165 ° C for section 2, 175 ° C for section 3, 175 ° C for section 4, 175 ° C for section 5, 170 ° C for section 6, 170 ° C for section 7, 170 ° C for section 8, and 165 ° C for section 9. Screw speed 350 r / min, feed rate 60 kg / h. The obtained masterbatch was dried for later use.

[0075] 2. Preparation of high barrier PE heat sealing film

[0076] Raw material weighing: Weigh 100 parts of HTPB modified LDPE masterbatch, 60 parts of POE, 100 parts of LDPE, and 0.002 parts of oleamide.

[0077] Mixing: High-speed mixer parameters: speed 850r / min, temperature 80℃, time 15min.

[0078] Film blowing: Film blowing temperature settings (unit: °C): 170°C for stage 1, 175°C for stage 2, 175°C for stage 3, 177°C for stage 4, and 177°C for stage 5. Screw speed: 300 r / min, blow-up ratio: 2.5, pulling speed: 10 m / min, producing a heat-sealable film with a thickness of 50 μm ± 2 μm.

[0079] 3. Performance Testing

[0080] The performance of the film was tested according to national standards. The heat seal strength test conditions were: 120°C, 0.2MPa, 1s. The results are as follows:

[0081]

[0082] This embodiment uses the highest ratio of HTPB and POE, and the film has the best barrier performance and excellent flexibility. It is suitable for scenarios with extremely high requirements for barrier properties and flexural resistance, such as cosmetics flexible packaging and pharmaceutical intermediate packaging.

[0083] Example 4: HTPB 8 parts + POE 55 parts

[0084] 1. Preparation of HTPB modified LDPE masterbatch

[0085] Raw material weighing: weigh 8 parts of HTPB and 100 parts of LDPE.

[0086] Mixing: High-speed mixer parameters: speed 820r / min, temperature 82℃, time 18min.

[0087] Extrusion granulation: Twin-screw extruder temperature settings (unit: ° C): 138 ° C for section 1, 158 ° C for section 2, 168 ° C for section 3, 168 ° C for section 4, 168 ° C for section 5, 162 ° C for section 6, 162 ° C for section 7, 162 ° C for section 8, and 158 ° C for section 9. Screw speed 310 r / min, feed rate 52 kg / h. The obtained masterbatch was dried for later use.

[0088] 2. Preparation of high barrier PE heat sealing film

[0089] Raw material weighing: weigh 60 parts of HTPB modified LDPE masterbatch, 55 parts of POE, 100 parts of LDPE, and 0.002 parts of oleamide.

[0090] Mixing: High-speed mixer parameters: speed 780r / min, temperature 73℃, time 13min.

[0091] Film blowing: Film blowing temperature settings (unit: °C): 163°C for stage 1, 172°C for stage 2, 170°C for stage 3, 175°C for stage 4, and 175°C for stage 5. Screw speed: 270 r / min, blow-up ratio: 2.3, pulling speed: 9.5 m / min, producing a heat-sealable film with a thickness of 50 μm ± 2 μm.

[0092] 3. Performance Testing

[0093] The performance of the film was tested according to national standards. The heat seal strength test conditions were: 120°C, 0.2MPa, 1s. The results are as follows:

[0094]

[0095] This embodiment has a balanced raw material ratio and moderate cost, and is suitable for popular packaging scenarios (such as daily necessities and snack foods), taking into account both barrier properties and economy.

[0096] Example 5: 12 parts of HTPB + 45 parts of POE

[0097] 1. Preparation of HTPB modified LDPE masterbatch

[0098] Raw material weighing: weigh 12 parts of HTPB and 100 parts of LDPE.

[0099] Mixing: High-speed mixer parameters: speed 870 r / min, temperature 87°C, time 22 min.

[0100] Extrusion granulation: Twin-screw extruder temperature settings (unit: ° C): 142 ° C for section 1, 162 ° C for section 2, 172 ° C for section 3, 172 ° C for section 4, 172 ° C for section 5, 167 ° C for section 6, 167 ° C for section 7, 167 ° C for section 8, and 162 ° C for section 9. Screw speed 330 r / min, feed rate 57 kg / h. The obtained masterbatch was dried for later use.

[0101] 2. Preparation of high barrier PE heat sealing film

[0102] Raw material weighing: weigh 85 parts of HTPB modified LDPE masterbatch, 45 parts of POE, 100 parts of LDPE, and 0.002 parts of oleamide.

[0103] Mixing: High-speed mixer parameters: speed 830 r / min, temperature 77°C, time 14 min.

[0104] Film blowing: Film blowing temperature settings (unit: °C): 167°C for stage 1, 171°C for stage 2, 170°C for stage 3, 173°C for stage 4, and 173°C for stage 5. Screw speed: 290 r / min, blow-up ratio: 2.4, pulling speed: 9.5 m / min, producing a heat-sealable film with a thickness of 50 μm ± 2 μm.

[0105] 3. Performance Testing

[0106] The performance of the film was tested according to national standards. The heat seal strength test conditions were: 120°C, 0.2MPa, 1s. The results are as follows:

[0107]

[0108] In this embodiment, the HTPB dosage is relatively high and the POE dosage is moderate. The barrier performance of the film is close to the optimal level, and the heat sealing strength is good, which is suitable for scenarios such as meat vacuum packaging and tea packaging.

[0109] Summary of the embodiments:

[0110] 1. Influence of raw material ratio on performance

[0111] All five groups of examples cover the raw material ratio range specified in the document (HTPB 5-15 parts, POE 40-60 parts). The test results show:

[0112] Barrier performance: With the increase of HTPB content, the oxygen transmission rate increases from 150cm 3 / m 2 24h 0.1MPa down to 100cm 3 / m 2 ·24h·0.1MPa, water vapor transmission rate from 2.0g / m 2 Reduced to 1.5 g / m2 in 24 hours 224h, indicating that HTPB is the key component to improve barrier properties;

[0113] Mechanical properties: As the POE content increases, the tensile elongation at break increases from 350% to 450%, the flexibility gradually increases, and the heat seal strength decreases slightly from 26N / 15mm to 23N / 15mm, reflecting the role of POE in improving the flexibility of the film.

[0114] 2. Correlation of process parameters

[0115] The extrusion temperature of all embodiments ranged from 135-145°C to 155-165°C, and the film blowing temperature ranged from 160-170°C to 165-177°C. As the amount of HTPB and POE increased, the temperature of each section increased gradually to match the melting requirements of the high-proportion modifier and ensure uniform plasticization of the material.

[0116] In order to verify the technical advantages of the present invention, the comparative experiments are designed as follows:

[0117] Control group 1: commercially available ordinary LDPE film (thickness 50 μm, unmodified);

[0118] Control group 2: PE film without HTPB (formulation: 200 parts of LDPE, 50 parts of POE, 0.002 parts of oleamide, process is the same as Example 2);

[0119] Control group 3: PE film without POE (formulation: 75 parts of HTPB modified masterbatch, 200 parts of LDPE, 0.002 parts of oleamide, process is the same as Example 2).

[0120] The performance of the film was tested according to national standards. The heat seal strength test conditions were: 120°C, 0.2MPa, 1s. The results are as follows:

[0121]

[0122] The barrier performance and flexibility of the experimental group were significantly better than those of the control group, proving that the synergistic effect of HTPB and POE can effectively solve the problem of traditional PE film being difficult to strike a balance between barrier properties and flexibility.

[0123] The present invention strictly controls the ratio of HTPB and POE and the extrusion and film blowing process parameters to prepare a high barrier PE heat-sealing film with an oxygen permeability of 100-150cm 3 / m 2 24h 0.1MPa, water vapor transmission rate 1.5-2g / m 224 hours, while also maintaining excellent mechanical and heat-sealing properties. Multiple examples covering diverse application scenarios have verified the universality and stability of the technical solution. Comparative experiments further highlight the technical advantages of this invention, which is applicable to packaging needs in multiple fields, including food, medicine, and cosmetics.

[0124] Finally, it should be noted that the above embodiments are merely examples for the purpose of illustrating the present invention and are not intended to limit the embodiments. Those skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. It is not necessary and impossible to provide an exhaustive list of all embodiments. However, obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A high barrier PE heat sealing film, characterized in that: The composition comprises the following components in parts by weight: 100 parts of low-density polyethylene (LDPE); 5-15 parts of hydroxyl-terminated polybutadiene HTPB; Polyolefin elastomer POE 40-60 parts; 0.002 parts of opening agent oleamide.

2. A high barrier PE heat sealing film according to claim 1, characterized in that: The melt flow rate of the low-density polyethylene is 2-4 g / 10 min, and the density is 0.915-0.925 g / cm 3 .

3. A high barrier PE heat sealing film according to claim 1, characterized in that: The number average molecular weight of the hydroxyl-terminated polybutadiene is 2000-3000, and the hydroxyl value is 0.8-1.2 mmol / g.

4. The high barrier PE heat-sealing film according to claim 1, characterized in that: The polyolefin elastomer is an ethylene-octene copolymer with a melt flow rate of 1-3 g / 10 min and a Shore A hardness of 60-80.

5. The high barrier PE heat-sealing film according to claim 1, characterized in that: The purity of the opener oleamide is ≥98%, and the melting point is between 72° C. and 76° C.

6. A method for preparing a high barrier PE heat-sealing film according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1 preparation of hydroxyl-terminated polybutadiene modified low-density polyethylene masterbatch: a) Weighing 5-15 parts by mass of hydroxy-terminated polybutadiene and 100 parts of low-density polyethylene; b) adding the above raw materials into a high-speed mixer and mixing at a speed of 800-900 r / min and a temperature of 80° C.-90° C. for 15-25 minutes until the hydroxyl-terminated polybutadiene is evenly dispersed on the surface of the low-density polyethylene particles and a mixture without obvious agglomeration is formed; c) The obtained mixture was fed into a twin-screw extruder with a length-to-diameter ratio of 40:1, and the temperature was controlled in sections according to the following temperature ranges: section 1 135-145°C, section 2 155-165°C, section 3 165-175°C, section 4 165-175°C, section 5 165-175°C, section 6 160-170°C, section 7 160-170°C, section 8 160-170°C, section 9 155-165°C, and the screw speed was maintained at The material is melted, sheared, and mixed at a speed of 280-350 r / min and extruded from a die. The material is then water-cooled at 20°C to 30°C and air-dried. The pelletizer cuts the material into cylindrical masterbatches with a particle size of 3-4 mm to obtain hydroxyl-terminated polybutadiene-modified low-density polyethylene masterbatches. The masterbatches are then dried in a blast drying oven at 55-65°C for 1.5-2.5 hours and sealed for storage. S2 preparation of high barrier PE heat-sealing film: a) Weighing 50-100 parts of hydroxyl-terminated polybutadiene-modified low-density polyethylene masterbatch, 40-60 parts of polyolefin elastomer, 100 parts of low-density polyethylene, and 0.002 parts of oleic acid amide as an opening agent, by mass; b) adding the above raw materials to a high-speed mixer, setting the speed at 750-850r / min and the temperature at 70°C-80°C and mixing for 10-15 minutes to ensure that the opening agent oleamide can be completely dispersed and no local aggregation occurs; c) The mixed material is fed into a single-screw film blowing machine and the temperature is controlled in sections according to the following temperature ranges: section 1 160-170°C, section 2 165-175°C, section 3 165-175°C, section 4 165-177°C, section 5 165-177°C, the screw speed is maintained at 250-300 r / min, the blow-up ratio is controlled between 1.8-2.5, the traction speed is set within the range of 7.5-10.5 m / min, and the air ring cooling temperature is maintained at 15-25°C. After the traction and winding processes, a high-barrier PE heat-sealable film with a thickness of 50 μm ± 2 μm is obtained.

7. The method for preparing a high barrier PE heat-sealing film according to claim 6, wherein: All the raw materials are pretreated before use, that is, the low-density polyethylene and polyolefin elastomer are placed in a vacuum drying oven at 55-65°C for 3.5-4.5 hours, and the terminal hydroxyl polybutadiene is dried in a vacuum drying oven at 35-45°C for 1.5-2.5 hours.

8. The method for preparing a high barrier PE heat-sealing film according to claim 6, wherein: During step S1, the temperature of each section of the twin-screw extruder is adjusted according to the amount of hydroxy-terminated polybutadiene and polyolefin elastomer used. As the amount increases, the temperature of each section shows a gradient upward trend to meet the melting requirement of a high proportion of the modifier.

9. The method for preparing a high barrier PE heat-sealing film according to claim 6, wherein: During step S2, the temperature of each section of the single-screw film blowing machine will also be adjusted according to the amount of terminal hydroxyl polybutadiene and polyolefin elastomer. As the amount increases, the temperature of each section also shows a gradient increase trend, thereby ensuring that the material can be evenly plasticized.

10. The method for preparing a high barrier PE heat-sealing film according to claim 6, wherein: The different ratios of HTPB and POE are suitable for different scenarios: low ratio is suitable for rigid packaging, medium ratio is suitable for food preservation, and high ratio is suitable for high-end scenarios such as cosmetics flexible packaging and pharmaceutical intermediate packaging.

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