Film composition and its use, interlayer material for films and ffs heavy duty packaging film

Abstract

The application relates to the field of plastic film modification, in particular to a film composition and application thereof, a middle layer material for films and the field of FFS heavy packaging films, and discloses a film composition which comprises the following components in parts by weight: linear low-density polyethylene 40-60, ultra-low-density polyethylene 40-60, polytetrafluoroethylene 5-10 and polyethylene glycol 1-2.5. The film composition is used as the middle layer of the FFS heavy packaging film, the film thickness is reduced, and the comprehensive performance can be simultaneously improved; the thickness of the FFS heavy packaging film product with the middle layer is approximately 118 microns, the tear resistance is approximately 35 N, the drop mark impact strength is approximately 800 g, the heat sealing temperature of the film during use is approximately 120 DEG, the packaging capacity is approximately 950 bags / hour, the heat sealing strength is approximately 47 N / 15 mm when the heat sealing strength is 160 DEG, the recovery rate is approximately 87%, the processability is excellent, the film thickness is reduced, and the production cost of the user can be saved.

Description

Technical Field

[0001] This invention relates to the field of plastic film modification, specifically to a film composition and its application, interlayer materials for films, and FFS heavy packaging film. Background Technology

[0002] With development, environmental protection and energy conservation have placed higher demands on packaging materials, such as lightweighting, high processing efficiency, high output, and low consumption. In existing technologies, the performance of heavy-duty packaging films deteriorates due to changes in external environmental temperature. For example, in winter, low temperatures in northern regions cause the film to become brittle and less resilient, easily leading to packaging film breakage and leakage. In summer, when temperatures reach around 30°C in both northern and southern regions, the plastic's resilience deteriorates, film strength decreases, and adhesion between layers weakens. Early polyethylene heavy-duty packaging films were mainly made from blends of general-purpose linear polyethylene and low-density polyethylene (LDPE) resins, but they were relatively thick, around 150-200 μm, resulting in high production costs and demanding requirements for production equipment and processes, making processing difficult. A common method was to add LDPE to improve the overall processing capability of the raw materials; however, the addition of LDPE significantly reduced the strength of the heavy-duty packaging film.

[0003] CN106079768B discloses a heavy packaging film and provides a heavy packaging film composition. Although the film has good mechanical properties, its thickness is between 140-250μm, which cannot reduce production and usage costs.

[0004] CN103059402B A method for preparing an FFS single-layer heavy packaging film is provided. Due to the use of single-layer extrusion processing, it is impossible to obtain a film with reduced thickness and high mechanical properties. The prepared film has low tear resistance and drop impact strength.

[0005] CN103029388.B discloses a three-layer co-extruded heavy packaging film and its preparation method, but does not specify the thickness of the film and the film has low tear resistance.

[0006] CN102452204B discloses an FFS film for heavy packaging. This technology uses a large amount of LDPE, which affects the overall strength of the film. At the same time, HDPE has stringent equipment requirements, which increases the difficulty of the production process of heavy packaging film and makes it difficult to promote its use.

[0007] CN103029388B discloses a three-layer co-extruded heavy packaging film. This technology has superior mechanical properties, good stiffness, and a moderate coefficient of friction on the film surface, but the heat sealing temperature is high and the energy consumption is large.

[0008] CN103059402A discloses an FFS single-layer heavy-duty packaging film and its preparation method, which improves the mechanical properties of the FFS single-layer heavy-duty packaging film by using ethylene-vinyl acetate copolymer, metallocene linear low-density polyethylene, and ultra-low-density polyethylene. However, the use of a certain amount of EVA in this technology leads to a decrease in the film's high-temperature resistance and a tendency for adhesion during processing. Since heavy-duty packaging films are mainly used for packaging 25 kg plastic granules, they require not only strength but also the ability to adapt to the operation of automated high-speed packaging production lines. The above technologies do not address processing efficiency; therefore, good film processability is beneficial for improving production efficiency. Summary of the Invention

[0009] The purpose of this invention is to overcome the problems of low processing efficiency, poor mechanical strength, poor heat-sealing performance, and poor rigidity-toughness balance in existing FFS heavy packaging films. This invention provides a film composition and its application, an interlayer material for the film, and an FFS heavy packaging film. Using the film composition of this invention as an interlayer in an FFS heavy packaging film reduces film thickness while simultaneously improving overall performance. FFS heavy packaging film products with the interlayer of this invention have a thickness ≤118μm, tear strength ≥35N, drop weight impact strength ≥800g, and can reduce the film heat-sealing temperature by ≤120℃. Packaging capacity ≥950 bags / hour, heat-sealing strength at 160℃ ≥47N / 15mm, recovery rate ≥87%, excellent processability, and reduced film thickness, thus saving users production costs.

[0010] To achieve the above objectives, the present invention provides a membrane composition comprising: 40-60 parts by weight of linear low-density polyethylene, 40-60 parts by weight of ultra-low-density polyethylene, 5-10 parts by weight of polytetrafluoroethylene, and 1-2.5 parts by weight of polyethylene glycol.

[0011] A second aspect of the present invention provides the use of the composition described herein in the preparation of a membrane interlayer.

[0012] A third aspect of the present invention provides an interlayer material for films formed from the raw materials of the compositions of the present invention.

[0013] A fourth aspect of the present invention provides an FFS repackaging film, wherein the intermediate layer of the FFS repackaging film contains the intermediate layer material of the present invention.

[0014] Through the above technical solution, the present invention has the following beneficial effects:

[0015] This invention proposes for the first time a film composition comprising: 40-60 parts by weight of linear low-density polyethylene, 40-60 parts by weight of ultra-low-density polyethylene, 5-10 parts by weight of polytetrafluoroethylene, and 1-2.5 parts by weight of polyethylene glycol. The FFS heavy-duty packaging film product having the intermediate layer of this invention has a thickness ≤118μm, tear strength ≥35N, drop weight impact strength ≥800g, and can reduce the film heat-sealing temperature by ≤120℃ during use. It has a packaging capacity ≥950 bags / hour, and a heat-sealing strength ≥160℃. With a thickness of 47 N / 15 mm and a recovery rate of ≥87%, it exhibits excellent processability. Simultaneously, the reduced film thickness saves users production costs. It is speculated that the synergistic effect of ultra-low density polyethylene and polytetrafluoroethylene, along with the interaction with polyethylene glycol dispersant, enables linear molecules to interconnect, forming a network structure. This results in tighter entanglement between molecular chains, increasing the adhesion between film layers, improving the film's puncture resistance, tear resistance, and resilience, while also enhancing the film's toughness and imparting a suitable coefficient of friction.

[0016] The FFS heavy packaging film of the present invention has uniform thickness and good performance. It can produce thinner FFS heavy packaging films with a thickness of 110-115μm, which is much thinner than the commonly available FFS heavy packaging films on the market. It has the advantages of thinness, light weight and low cost.

[0017] In a preferred embodiment of the present invention, metallocene polyethylene with a specific molecular structure, ultra-low density polyethylene with a specific molecular structure, ultra-fine polytetrafluoroethylene powder, and polyethylene glycol are blended to obtain a polyethylene heavy-duty packaging film with reduced film thickness and improved overall performance. The thickness of this film product is ≤118μm, tear strength ≥35N, drop impact strength ≥800g, and the film heat sealing temperature can be reduced by ≤120℃ during use. The packaging capacity is ≥950 bags / hour, the heat sealing strength is ≥47N / 15mm at 160℃, the recovery rate is ≥87%, and the processability is excellent. At the same time, the reduced film thickness can save users production costs. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] This invention proposes for the first time a film composition comprising: 40-60 parts by weight of linear low-density polyethylene, 40-60 parts by weight of ultra-low-density polyethylene, 5-10 parts by weight of polytetrafluoroethylene, and 1-2.5 parts by weight of polyethylene glycol. Using this film composition as an interlayer in an FFS heavy-duty packaging film reduces film thickness while simultaneously improving overall performance. FFS heavy-duty packaging film products with this invention's interlayer have a thickness ≤118μm, tear strength ≥35N, and drop weight impact strength ≥800g. During use, the film heat-sealing temperature can be reduced by ≤120°C. Packaging capacity ≥950 bags / hour, heat sealing strength ≥47 N / 15 mm at 160℃ or higher, recovery rate ≥87%, excellent processability, and reduced film thickness, which can save users production costs; it is speculated that due to the synergistic effect of ultra-low density polyethylene and polytetrafluoroethylene, and the action of polyethylene glycol dispersant, linear molecules can be linked together to form a network structure. This makes the molecular chains more tightly intertwined, increases the adhesion between film layers, improves the film's puncture resistance, tear resistance and resilience, while also improving the film's toughness and giving it a suitable coefficient of friction.

[0020] In this invention, the density of the linear low-density polyethylene can be a conventional choice in the art. According to a preferred embodiment of the invention, the density of the linear low-density polyethylene is 0.92-0.93 g / cm³. 3 The preferred value is 0.923-0.926 g / cm³. 3 By adopting the aforementioned preferred embodiments, the puncture resistance, tear resistance, processability, and resilience of the film can be further improved, and the thickness can be further reduced, thereby improving the stability of the film bubble.

[0021] In this invention, the density of the ultra-low density polyethylene can be a conventional choice in the art. According to a preferred embodiment of the invention, the density of the ultra-low density polyethylene is 0.885-0.909 g / cm³. 3 The preferred value is 0.886-0.903 g / cm³. 3 By adopting the aforementioned preferred embodiments, the puncture resistance, tear resistance, processability, and resilience of the film can be further improved, and the thickness can be further reduced, thereby improving the stability of the film bubble.

[0022] In this invention, the melt flow rate of the linear low-density polyethylene at 190 ≤ / 2.16 kg can be a conventional choice in the art. According to a preferred embodiment of the invention, the melt flow rate of the linear low-density polyethylene at 190 ≤ / 2.16 kg is 3.1-4.0 g / 10 min, preferably 3.2-3.6 g / 10 min. By adopting the aforementioned preferred embodiment, the heat-sealing temperature of the film can be further reduced.

[0023] In this invention, the melt flow rate of the ultra-low density polyethylene at 190 ≤ / 2.16 kg can be a conventional choice in the art. According to a preferred embodiment of the invention, the melt flow rate of the ultra-low density polyethylene at 190 ≤ / 2.16 kg is 0.8-3.2 g / 10 min, preferably 1.5-2.1 g / 10 min. By adopting the aforementioned preferred embodiment, the heat-sealing temperature of the film can be further reduced.

[0024] In this invention, the molecular weight distribution of the ultra-low density polyethylene can be a conventional choice in the art. According to a preferred embodiment of the invention, the molecular weight distribution of the ultra-low density polyethylene is 3.8-5.0. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0025] In this invention, the ultra-low density polyethylene in the intermediate layer is a vinyl linear copolymer. During polymerization, 4-20% of a higher α-olefin comonomer is added using a metallocene catalyst. The ultra-low density polyethylene contains structural unit a provided by the ethylene monomer and structural unit b provided by the comonomer. According to a preferred embodiment of the invention, the molar content of the ultra-low density polyethylene structural unit b is 8-10 mol%, and the comonomer is selected from at least one of propylene, butene, hexene, and octene, preferably hexene. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0026] In this invention, the mass percentage of lamellar crystals with a thickness of less than 6.2 nm in the thermal grading analysis of ultra-low density polyethylene can be a conventional choice in the art. According to a preferred embodiment of the invention, the mass percentage of lamellar crystals with a thickness of less than 6.2 nm in the thermal grading analysis of ultra-low density polyethylene is 7.1-8.9%, preferably 7.5-8.5%. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0027] In this invention, the method for testing the thermal gradation of crystallization has no special requirements and can be carried out according to existing technology, which will not be elaborated here.

[0028] In this invention, the number of branches in the ultra-low density polyethylene can be a conventional choice in the art. According to a preferred embodiment of the invention, the number of branches in the ultra-low density polyethylene is 17.1-18.0 / 1000C. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0029] In this invention, the molecular weight of the polytetrafluoroethylene (PTFE) can be a conventional choice in the art. According to a preferred embodiment of the invention, the molecular weight of the PTFE is 6000-8000. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0030] In this invention, the polytetrafluoroethylene (PTFE) particle size can be a conventional choice in the art. According to a preferred embodiment of the invention, the PTFE particle size is 0.5-2 μm. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0031] In this invention, the molecular weight of the polyethylene glycol can be a conventional choice in the art. According to a preferred embodiment of the invention, the molecular weight of the polyethylene glycol is 2000-6000. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0032] This invention does not have special requirements for the physicochemical parameters of polytetrafluoroethylene. For this invention, it is preferred that the polytetrafluoroethylene is modified polytetrafluoroethylene treated with a modifier.

[0033] In this invention, the method for treating polytetrafluoroethylene (PTFE) with the modifier can be a conventional choice in the art. According to a preferred embodiment of the invention, the method for treating PTFE with the modifier includes: impregnation in the presence of the modifier, washing, solid-liquid separation, and drying. By adopting the aforementioned preferred embodiment, the compatibility between the components can be further improved, which is beneficial to further improving the film performance.

[0034] In this invention, the modifier can be a conventional choice in the art.

[0035] According to a preferred embodiment of the present invention, the modifier is selected from at least one of tribomethyl ethyl ether, tetrahydrofuran, dioxane, isopropanol and chloroform.

[0036] According to a preferred embodiment of the present invention, the modifier is selected from a mixture of tetrahydrofuran and isopropanol.

[0037] According to a preferred embodiment of the present invention, the ratio of tetrahydrofuran to isopropanol in the modifier is (7-9):(1-2.5).

[0038] By adopting the aforementioned preferred embodiments, the fusion between the components can be further improved, which is beneficial to further improving the performance of the film.

[0039] In this invention, the organic solvent used for washing can be a conventional choice in the art. According to a preferred embodiment of the invention, the organic solvent is selected from propanol and / or acetone, preferably acetone. By employing the aforementioned preferred embodiment, the compatibility between the components can be further improved, which is beneficial for further improving the film performance.

[0040] In this invention, there are no special requirements for the washing time with organic solvents; it can be carried out according to the actual operation.

[0041] In this invention, after washing with organic solvent and before solid-liquid separation, a step of dispersing with an ultrasonic cell disruptor (power 500W) for 20 minutes is required.

[0042] In this invention, the drying conditions can be conventionally selected in the art.

[0043] According to a preferred embodiment of the present invention, the drying temperature is 55-85°C.

[0044] According to a preferred embodiment of the present invention, the drying time is 20-30 hours.

[0045] By adopting the aforementioned preferred embodiments, the compatibility between the components can be further improved.

[0046] In this invention, after the drying step, a crushing and grinding step is also required.

[0047] In this invention, the conditions for the impregnation treatment can be conventional choices in the art.

[0048] According to a preferred embodiment of the present invention, the temperature of the impregnation treatment is -5 to 10°C.

[0049] According to a preferred embodiment of the present invention, the immersion time is 5-10 minutes.

[0050] By adopting the aforementioned preferred embodiments, it is possible to further improve the uniformity and fineness of the modified filler powder and ensure sufficient reaction with the base resin.

[0051] The present invention provides the use of the membrane composition described herein in the preparation of membrane interlayers, preferably in the use of FFS heavy packaging membrane interlayers.

[0052] This invention provides an interlayer material for membranes, formed from the raw materials of the composition described herein, exhibiting excellent processability and a good balance of rigidity and toughness. By employing the aforementioned preferred embodiments, tear resistance and nominal strain can be further improved.

[0053] This invention provides an FFS heavy-duty packaging film, wherein the intermediate layer of the FFS heavy-duty packaging film contains the intermediate layer material described in this invention. According to a preferred embodiment of this invention, the FFS heavy-duty packaging film comprises an outer layer, an inner layer, and the intermediate layer. This invention's FFS heavy-duty packaging film rationally distributes the outer mold, inner film, and intermediate layer film, leveraging the advantages of each film layer while achieving synergistic effects, improving the adhesion between film layers, and enhancing the overall performance of the film. Heavy-duty packaging bags not only require strength but also need to consider heat-sealing, stiffness, and palletizing properties. This invention achieves these properties through co-extrusion of the outer, intermediate, and inner layers. The resulting film possesses excellent processing performance and a good balance of rigidity and toughness, good tear resistance, and a low heat-sealing temperature. The outer, intermediate, and inner layer structure of this invention can replace the traditional four-layer material, significantly reducing production costs.

[0054] In this invention, the thickness ratio of the three composite structures—outer layer, middle layer, and inner layer—can be a conventional choice in the art. According to a preferred embodiment of this invention, the thickness ratio of the three composite structures is (1-2.0):(1-2.0):1. By adopting the aforementioned preferred embodiment, the overall performance of the film can be further improved, achieving excellent mechanical properties while reducing film thickness.

[0055] According to a preferred embodiment of the present invention, the thickness of the FFS repackaging film is ≤118μm.

[0056] According to a preferred embodiment of the present invention, the tear resistance of the FFS repackaging film is ≥35N.

[0057] According to a preferred embodiment of the present invention, the drop impact strength of the FFS heavy packaging film is ≥800g.

[0058] According to a preferred embodiment of the present invention, the FFS repackaging film can reduce the film heat sealing temperature by ≤120°C when used.

[0059] According to a preferred embodiment of the present invention, the FFS heavy packaging film has a packaging capacity of ≥950 bags / hour.

[0060] According to a preferred embodiment of the present invention, the heat-sealing strength of the FFS repackaging film is ≥47 N / 15 mm when the temperature is ≥160°C.

[0061] According to a preferred embodiment of the present invention, the recovery rate of the FFS repackaging film is ≥87%.

[0062] By employing the aforementioned preferred embodiments, the mechanical properties of the thin film can be further improved.

[0063] In this invention, the composition of the outer layer of the FFS heavy-duty packaging film by weight is not particularly required. According to a preferred embodiment of the invention, the outer layer of the FFS heavy-duty packaging film by weight comprises: 70-90 parts by weight of metallocene linear polyethylene, 10-30 parts by weight of ultra-low density polyethylene, and 0.2-1.0 parts by weight of polyethylene glycol. By adopting the aforementioned preferred embodiment, the tensile strength and drop impact strength can be further improved.

[0064] In this invention, the composition of the inner layer of the FFS heavy-duty packaging film by weight is not particularly required. According to a preferred embodiment of the invention, the composition of the inner layer of the FFS heavy-duty packaging film by weight includes: 70-90 parts by weight of metallocene linear polyethylene, 10-30 parts by weight of ultra-low density polyethylene, and 1-3 parts by weight of TiO2 masterbatch. By adopting the aforementioned preferred embodiment, the tensile strength and drop weight impact strength can be further improved.

[0065] In this invention, the properties of the metallocene linear polyethylene in the inner and outer layers are not particularly required. According to a preferred embodiment of the invention, the physicochemical properties of the metallocene linear polyethylene in the inner and outer layers include: a melt flow rate of 190 ≤ / 2.16 kg.

[0066] 2.02g / 10min-3.2g / 10min, preferably 2.02-2.23g / 10min.

[0067] According to a preferred embodiment of the present invention, the physicochemical properties of the metallocene linear polyethylene in the inner and outer layers respectively include: a density of 0.920-0.935 g / cm³. 3 The preferred value is 0.921-0.930 g / cm³. 3 .

[0068] According to a preferred embodiment of the present invention, the physicochemical properties of the metallocene linear polyethylene in the inner layer and the outer layer respectively include: molecular weight distribution of 3.3-3.8, weight-average molecular weight of 120,000-160,000, preferably 130,000-150,000.

[0069] According to a preferred embodiment of the present invention, the physicochemical properties of the metallocene linear polyethylene in the inner layer and the outer layer include: a relative content of lamellar crystals with a thickness of 9.6 nm or more, preferably 13-15%, as determined by thermal crystallization grading analysis.

[0070] According to a preferred embodiment of the present invention, the physicochemical properties of the metallocene linear polyethylene in the inner layer and the outer layer include: a branch number of 11.8-13.5 / 1000C.

[0071] By adopting the aforementioned preferred embodiments, the mechanical properties of the film can be further improved, and the strength of the film can be guaranteed.

[0072] In this invention, the properties of the outer ultra-low density polyethylene are not particularly required. According to a preferred embodiment of this invention, the physicochemical parameters of the ultra-low density polyethylene in the outer layer include:

[0073] The melt mass flow rate at 190≯ / 2.16kg is 0.5-2.5g / 10min, preferably 0.8-1.6g / 10min.

[0074] According to a preferred embodiment of the present invention, the physicochemical parameters of the ultra-low density polyethylene in the outer layer include: a density of 0.908-0.915 g / cm³. 3 The preferred value is 0.909-0.912 g / cm³. 3 .

[0075] According to a preferred embodiment of the present invention, the physicochemical parameters of the ultra-low density polyethylene in the outer layer include: a molecular weight distribution of 3.8-4.1, and a mass percentage of 9.4 nm thick lamellar crystals of 8.0-9.2%, preferably 8.5-8.9%, as determined by thermal grading analysis.

[0076] According to a preferred embodiment of the present invention, the physicochemical parameters of the ultra-low density polyethylene in the outer layer include: branch number 14.5-17.0 / 1000C.

[0077] By employing the aforementioned preferred embodiments, the combination of ultra-low density polyethylene and metallocene linear polyethylene with this specific structure can further improve the strength of the film.

[0078] In this invention, the outer ultra-low density polyethylene is a vinyl linear copolymer. During polymerization, 4-20% of a higher α-olefin comonomer is added using a metallocene catalyst. The ultra-low density polyethylene contains structural unit a provided by the ethylene monomer and structural unit b provided by the comonomer. According to a preferred embodiment of the invention, the molar content of the ultra-low density polyethylene structural unit b is 4.2-5.5 mol%, and the comonomer is selected from at least one of propylene, butene, hexene, and octene, preferably hexene. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0079] In this invention, the molecular weight of the outer layer polyethylene glycol is not particularly required. According to a preferred embodiment of the invention, the molecular weight of the outer layer polyethylene glycol is 2000-6000. By adopting the aforementioned preferred embodiment, the tear resistance of the film can be further improved.

[0080] In this invention, the properties of the ultra-low density polyethylene in the inner layer are not particularly required. According to a preferred embodiment of the invention, the physicochemical parameters of the ultra-low density polyethylene in the inner layer include: a melt flow rate of 0.8-3.2 g / 10 min at 190 ≤ / 2.16 kg, preferably 0.886-0.903 g / cm³. 3 .

[0081] According to a preferred embodiment of the present invention, the physicochemical parameters of the ultra-low density polyethylene in the inner layer include: a molecular weight distribution of 3.8-5.0.

[0082] According to a preferred embodiment of the present invention, the physicochemical parameters of the ultra-low density polyethylene in the inner layer include: the mass percentage of lamellar crystals with a thickness of less than 6.2 nm, as determined by thermal grading analysis, is 7.1-8.9%, preferably 7.5-8.5%.

[0083] According to a preferred embodiment of the present invention, the physicochemical parameters of the ultra-low density polyethylene in the inner layer include: branch number 17.1-18.0 / 1000C.

[0084] By employing the aforementioned preferred embodiments, the strength of the film can be further improved.

[0085] In this invention, the metallocene linear polyethylene in the inner and / or outer layers is a copolymer of ethylene and α-olefins (such as 1-butene, 1-hexene or 1-octene) under the action of a metallocene catalytic system. Preferably, the metallocene linear polyethylene is a copolymer of ethylene and 1-hexene.

[0086] In this invention, the preparation of each membrane layer typically includes the steps of raw material mixing, extrusion, and compounding. This invention does not have special requirements for the technology of raw material mixing, extrusion, and compounding, and existing technologies can be used for all of them.

[0087] According to a preferred embodiment of the present invention, the method for repackaging FFS film includes the following steps:

[0088] (1.1) Preparation of inner layer thin film raw materials:

[0089] Weigh the inner layer components according to weight, put them into a high-speed mixer for mixing at a mixing temperature of 15°C, a mixing speed of 860 rpm, and a mixing time of 16 min; then feed them into a first single-screw extruder (50 mm diameter, length-to-diameter ratio 32:1) for compounding. The screw temperature of the first single-screw extruder is 180°C, the die head temperature of the first single-screw extruder is 210°C, the screw speed is 110 rpm, and the extrusion processing pressure is 58 MPa to obtain the inner layer film raw material;

[0090] (1.2) Preparation of intermediate layer film raw materials:

[0091] Polytetrafluoroethylene was first impregnated in a frozen solution of tetrahydrofuran and isopropanol (weight ratio 4:1) for 10 minutes, then rinsed with acetone for 8 minutes, dispersed in an ultrasonic cell disruptor (power 500W) for 20 minutes, the solvent was removed by a rotary evaporator, filtered, and dried under vacuum at 70°C for 24 hours until constant weight was achieved. The resulting powder had a small amount of agglomeration. It was then ground in a small grinder for 1 hour before use.

[0092] Weigh out polytetrafluoroethylene powder, ultra-low density polyethylene, and polyethylene glycol powder according to weight, and put them into a high-speed mixer for mixing. The mixing temperature is 38°C, the mixing speed is 1100 rpm, and the mixing time is 15 minutes. Then, metallocene linear polyethylene is added and mixed for 8 minutes. Then, it is fed into a second single-screw extruder (55 mm in diameter, length-to-diameter ratio 35:1) for compounding. The screw temperature of the second single-screw extruder is 218°C, the die head temperature of the second single-screw extruder is 210°C, the screw speed is 109 rpm, and the extrusion processing pressure is 37 MPa to obtain the intermediate layer film raw material.

[0093] (1.3) Preparation of outer thin film raw materials:

[0094] Weigh the outer layer components according to weight, put them into a high-speed mixer for mixing at a mixing temperature of 16°C, a mixing speed of 800 rpm, and a mixing time of 17 min; then feed the mixture into a third single-screw extruder (diameter 65 mm, length-to-diameter ratio 36:1) for compounding at a screw temperature of 190°C, a die temperature of 210°C, a screw speed of 110 rpm, and an extrusion processing pressure of 40 MPa to obtain the outer layer film raw material;

[0095] (2) Extrusion molding: The fluidized inner layer film material, middle layer film material and outer layer film material are simultaneously fed into a three-layer co-extruder for fusion at a fusion temperature of 230°C and then flowed into the blown film die head at a temperature of 230°C. After extrusion through the die head, film bubbles are formed.

[0096] (3) Cooling and shaping:

[0097] The film bubble is cooled and shaped by 18°C ​​cooling air, and then rolled up to obtain the heavy packaging film.

[0098] The present invention will be described in detail below through embodiments.

[0099] The preparation steps and conditions for the inner, outer, and middle layer materials in this embodiment are as follows:

[0100] (1.1) Preparation of inner layer thin film raw materials:

[0101] Weigh the inner layer components according to weight, put them into a high-speed mixer for mixing at a mixing temperature of 15°C, a mixing speed of 860 rpm, and a mixing time of 16 min; then feed them into a first single-screw extruder (50 mm diameter, length-to-diameter ratio 32:1) for compounding. The screw temperature of the first single-screw extruder is 180°C, the die head temperature of the first single-screw extruder is 210°C, the screw speed is 110 rpm, and the extrusion processing pressure is 58 MPa to obtain the inner layer film raw material;

[0102] (1.2) Preparation of intermediate layer film raw materials:

[0103] Polytetrafluoroethylene modification:

[0104] Polytetrafluoroethylene was first impregnated in a frozen mixture of tetrahydrofuran and isopropanol (4:1 ratio) for 10 minutes, then rinsed with acetone for 8 minutes, dispersed in an ultrasonic cell disruptor (500W power) for 20 minutes, the solvent was removed by a rotary evaporator, filtered, and dried under vacuum at 70°C for 24 hours until constant weight was obtained. The resulting powder had a small amount of agglomeration. It was then ground in a small grinder for 1 hour before use.

[0105] Weigh out polytetrafluoroethylene, ultra-low density polyethylene, and polyethylene glycol powder according to weight, add them to a high-speed mixer and mix at a mixing temperature of 35°C, a mixing speed of 1100 rpm, and a mixing time of 15 minutes. Then add LLDPE and mix for 8 minutes. Then feed it into a second single-screw extruder (55 mm diameter, length-to-diameter ratio 35:1) for compounding. The screw temperature of the second single-screw extruder is 210°C, the die head temperature of the second single-screw extruder is 220°C, the screw speed is 110 rpm, and the extrusion processing pressure is 40 MPa to obtain the intermediate layer film raw material.

[0106] (1.3) Preparation of outer thin film raw materials:

[0107] Weigh the outer layer components according to weight, put them into a high-speed mixer for mixing at a mixing temperature of 16°C, a mixing speed of 800 rpm, and a mixing time of 15 min; then feed the mixture into a third single-screw extruder (diameter 65 mm, length-to-diameter ratio 36:1) for compounding. The screw temperature of the third single-screw extruder is 190°C, the die temperature of the third single-screw extruder is 210°C, the screw speed is 110 rpm, and the extrusion processing pressure is 40 MPa to obtain the outer layer film raw material;

[0108] (2) Extrusion molding: The fluidized inner layer film material, middle layer film material and outer layer film material are simultaneously fed into a three-layer co-extruder for fusion at a fusion temperature of 230°C and then flowed into the blown film die head at a temperature of 230°C. After extrusion through the die head, film bubbles are formed.

[0109] (3) Cooling and shaping:

[0110] The film bubble is cooled and shaped by 15°C cooling air, and then rolled up to obtain the heavy packaging film.

[0111] In this invention

[0112] Performance testing standards for heavy packaging films:

[0113] Tensile strength and nominal strain at break: in accordance with GB / T1040.3-2006.

[0114] Drop impact strength: according to GB / T9639-2008.

[0115] Tear resistance: Tested according to GB / T11999-1989, using rectangular specimens.

[0116] Heat sealing temperature: Follow YBB00122003.

[0117] Heat sealing strength: in accordance with YBB00122003-2015.

[0118] Coefficient of friction: in accordance with GB / T10006-1988.

[0119] Resilience: in accordance with GB / T10006-1988.

[0120] Density: The sample was prepared by compression molding according to Method A in GB / T 1033.1-2010.

[0121] Melt mass flow rate (MFR): Performed according to GB / T 3682.1-2008, the test temperature is 190°C, the nominal load is 2.16 kg, take 50 g of sample and dry it in a vacuum oven at 90°C for 4 h, and then test it immediately after taking it out.

[0122] The crystallization thermal grading test method in this experiment:

[0123] Approximately 6 mg of sample was weighed and sealed in a crucible, then placed in a differential scanning calorimeter (DSC). First, the sample was heated to 165°C at a rate of 50°C / min and held at that temperature for 5 min to eliminate thermal history. Then, the sample was cooled to 0°C at a rate of 25°C / min and held at that temperature for 3 min. Next, the sample was heated to the set nucleation temperature at a rate of 25°C / min and held at that temperature for 5 min, then cooled to 25°C at a rate of 25°C / min, and then heated to the next nucleation temperature at a rate of 25°C / min, and this cycle was repeated. The nucleation temperatures were (135, 125, 115, 115, 110, 105, 100°C). Finally, the sample was cooled from 80°C to 25°C at a rate of 25°C / min and held at that temperature for 3 min; then, the sample was heated to 160°C at a rate of 25°C / min. Record the final DSC temperature rise curve; Q20 differential scanning calorimeter, TA Instruments, USA.

[0124] The performance test results of FFS heavy packaging film are shown in Table 1.

[0125] Example 1

[0126] The FFS heavy packaging film provided in this embodiment comprises three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are as follows:

[0127] The outer layer consists of the following components in parts by weight:

[0128] The MFR (190 ≤, 2.16 kg) of metallocene linear polyethylene is 2.02 g / 10 min, and its density is 0.921 g / cm³. 3 The molecular weight distribution is 3.35, the weight average molecular weight is 140,000, and the relative content of lamellar crystals with a thickness of 9.6 nm or more is 13.2% according to the thermal fractionation of crystallization (SSA) analysis. The branch number is 11.9 / 1000C; 70 parts.

[0129] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 1.6 g / 10 min, and its density is 0.909 g / cm³. 3 The molecular weight distribution was 4.0, the hexene molar content was 4.6 mol%, the number of branches was 14.7 / 1000C, and the mass percentage of the 9.4 nm thick lamellar crystals was 8.6% by thermal fractionation of crystallization (SSA); 30 parts.

[0130] Polyethylene glycol molecular weight 2100; 0.3 parts.

[0131] The intermediate layer consists of the following components in parts by weight:

[0132] The linear low-density polyethylene (LLDPE) MFR (190 ≤ 2.16 kg) is 3.2 g / 10 min, and its density is 0.923 g / cm³. 3 40 copies.

[0133] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 1.5 g / 10 min, and its density is 0.902 g / cm³. 3 The molecular weight distribution is 4.0, the hexene molar content is 8.2 mol%, and the branching number is 17.4 / 1000C. The mass percentage of lamellar crystals with a thickness less than 6.2 nm, analyzed by thermal fractionation of crystallization (SSA), is 7.5%; 50 parts.

[0134] Polytetrafluoroethylene (PTFE) with a molecular weight of 6500 and a particle size of 0.8 μm; 10 parts.

[0135] Polyethylene glycol molecular weight 5100; 1.4 parts.

[0136] The inner layer consists of the following components in parts by weight:

[0137] Metallocene linear polyethylene (same as outer layer); 70 parts.

[0138] Ultra-low density polyethylene (same as intermediate layer); 30 parts.

[0139] TiO2 masterbatch; 1.5 parts.

[0140] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:2:1, and the performance test results are shown in Table 1.

[0141] Example 2

[0142] The FFS heavy packaging film provided in this embodiment comprises three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are as follows:

[0143] The outer layer consists of the following components in parts by weight:

[0144] The MFR (190 ≤, 2.16 kg) of metallocene linear polyethylene is 2.20 g / 10 min, and its density is 0.924 g / cm³. 3 The molecular weight distribution is 3.55, the weight-average molecular weight is 145,000, and the relative content of lamellar crystals with a thickness of 9.6 nm or more is 13.6% by thermal fractionation of crystallization (SSA). The branching number is 12.3 / 1000C; 85 parts.

[0145] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 0.8 g / 10 min, and its density is 0.910 g / cm³. 3 The molecular weight distribution is 3.84, the hexene molar content is 4.2 mol%, the number of branches is 15.6 / 1000C, and the mass percentage of the 9.4 nm thick lamellar crystals is 8.8% according to the thermal fractionation of crystallization (SSA); 15 parts.

[0146] Polyethylene glycol molecular weight 3000; 0.2 parts.

[0147] The intermediate layer consists of the following components in parts by weight:

[0148] The linear low-density polyethylene (LLDPE) MFR (190 ≤ 2.16 kg) is 3.6 g / 10 min, and its density is 0.926 g / cm³. 3 42 copies.

[0149] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 1.64 g / 10 min, and its density is 0.889 g / cm³. 3The molecular weight distribution is 4.5, the hexene molar content is 9.5 mol%, and the branching number is 17.8 / 1000C. The mass percentage of lamellar crystals with a thickness less than 6.2 nm, analyzed by thermal fractionation of crystallization (SSA), is 7.6%; 50 parts.

[0150] Polytetrafluoroethylene (PTFE) with a molecular weight of 7000 and a particle size of 1.0 μm; 8 parts.

[0151] Polyethylene glycol molecular weight 4000; 1.5 parts.

[0152] The inner layer consists of the following components in parts by weight:

[0153] Metallocene linear polyethylene (same as outer layer); 75 parts.

[0154] Ultra-low density polyethylene (same as intermediate layer); 25 parts.

[0155] TiO2 masterbatch; 1.3 parts.

[0156] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1.5:2:1, and the performance test results are shown in Table 1.

[0157] Example 3

[0158] The FFS heavy packaging film provided in this embodiment comprises three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are as follows:

[0159] The outer layer consists of the following components in parts by weight:

[0160] The MFR (190 ≤, 2.16 kg) of metallocene linear polyethylene is 2.1 g / 10 min, and its density is 0.930 g / cm³. 3 The molecular weight distribution is 3.7, the weight-average molecular weight is 138,000, and the relative content of lamellar crystals with a thickness of 9.6 nm or more is 13.9% by thermal fractionation of crystallization (SSA). The branching number is 12 / 1000C; 88 parts.

[0161] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 1.2 g / 10 min, and its density is 0.906 g / cm³. 3 The molecular weight distribution is 3.91, the hexene molar content is 5.2 mol%, the number of branches is 16.4 / 1000C, and the mass percentage of the 9.4 nm thick lamellar crystals is 8.7% according to the thermal fractionation of crystallization (SSA); 12 parts.

[0162] Polyethylene glycol molecular weight 2500; 0.4 parts.

[0163] The intermediate layer consists of the following components in parts by weight:

[0164] The linear low-density polyethylene (LLDPE) MFR (190 ≤ 2.16 kg) is 3.3 g / 10 min, and its density is 0.924 g / cm³. 3 50 copies.

[0165] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 2.0 g / 10 min, and its density is 0.887 g / cm³. 3 Molecular weight distribution 4.2, hexene molar content 9.0 mol%, branch number 18.0 / 1000C. Thermal fractionation (SSA) analysis showed that the mass percentage of lamellar crystals with a thickness less than 6.2 nm was 8.5%; 45 parts.

[0166] Polytetrafluoroethylene (PTFE) with a molecular weight of 7500 and a particle size of 1.5 μm; 5 parts.

[0167] Polyethylene glycol molecular weight 4500; 1.6 parts.

[0168] The inner layer consists of the following components in parts by weight:

[0169] Metallocene linear polyethylene (same as outer layer); 85 parts.

[0170] Ultra-low density polyethylene (same as intermediate layer); 15 parts.

[0171] TiO2 masterbatch; 1.8 parts.

[0172] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1.5:1.5:1, and the performance test results are shown in Table 1.

[0173] Example 4

[0174] The FFS heavy packaging film provided in this embodiment comprises three parts arranged sequentially from the outside to the inside: a middle layer, an inner layer, and the raw materials and their proportions for each layer are as follows:

[0175] The outer layer of metallocene linear polyethylene (MFR) and its density are not within the preferred range of this invention. The outer layer is composed of the following components in parts by weight:

[0176] The metallocene linear polyethylene MFR (190 ≤, 2.16 kg) is 3.0 g / 10 min, and its density is 0.920 g / cm³. 3 The molecular weight distribution is 3.62, the weight-average molecular weight is 135,000, and the relative content of lamellar crystals with a thickness of 9.6 nm or more is 14.4% by thermal fractionation of crystallization (SSA). The branching number is 13 / 1000C; 75 parts.

[0177] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 0.9 g / 10 min, and its density is 0.911 g / cm³. 3The molecular weight distribution was 4.1, the hexene molar content was 5.0 mol%, the number of branches was 14.5 / 1000C, and the mass percentage of the 9.4 nm thick lamellar crystals was 8.75% by thermal fractionation of crystallization (SSA); 25 parts.

[0178] Polyethylene glycol molecular weight 2700; 0.25 parts.

[0179] The intermediate layer consists of the following components in parts by weight:

[0180] The linear low-density polyethylene (LLDPE) MFR (190 ≤, 2.16 kg) is 3.4 g / 10 min, and its density is 0.925 g / cm³. 3 55 copies.

[0181] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 1.8 g / 10 min, and its density is 0.900 g / cm³. 3 Molecular weight distribution 4.7, hexene molar content 10 mol%, branch number 17.5 / 1000C. Thermal fractionation (SSA) analysis showed that the mass percentage of lamellar crystals with a thickness less than 6.2 nm was 8.2%; 40 parts.

[0182] Polytetrafluoroethylene (PTFE) with a molecular weight of 6800 and a particle size of 2.0 μm; 7 parts.

[0183] Polyethylene glycol molecular weight 4800; 2.0 parts.

[0184] The inner layer consists of the following components in parts by weight:

[0185] Metallocene linear polyethylene (same as outer layer); 80 parts.

[0186] Ultra-low density polyethylene (same as intermediate layer); 20 parts.

[0187] TiO2 masterbatch; 1.6 parts.

[0188] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:1:1, and the performance test results are shown in Table 1.

[0189] Example 5

[0190] The FFS heavy packaging film provided in this embodiment comprises three parts arranged sequentially from the outside to the inside: a middle layer, an inner layer, and the raw materials and their proportions for each layer are as follows:

[0191] The outer metallocene linear polyethylene (MFR) layer is not within the preferred scope of this invention, and the outer layer is composed of the following components in parts by weight:

[0192] The MFR (190 ≤, 2.16 kg) of metallocene linear polyethylene is 2.6 g / 10 min, and its density is 0.923 g / cm³.3 The molecular weight distribution was 3.46, the weight-average molecular weight was 150,000, and the relative content of lamellar crystals with a thickness of 9.6 nm or more was 14.9% by thermal fractionation of crystallization (SSA). The branching number was 13.0 / 1000C; 88 parts.

[0193] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 1.4 g / 10 min, and its density is 0.912 g / cm³. 3 The molecular weight distribution was 4.05, the hexene molar content was 4.8 mol%, the number of branches was 17.0 / 1000C, and the mass percentage of the 9.4 nm thick lamellar crystals was 8.5% by thermal fractionation of crystallization (SSA); 12 parts.

[0194] Polyethylene glycol molecular weight 2330; 0.35 parts.

[0195] The intermediate layer consists of the following components in parts by weight:

[0196] The linear low-density polyethylene (LLDPE) MFR (190 ≤ 2.16 kg) is 3.5 g / 10 min, and its density is 0.92386 g / cm³. 3 60 copies.

[0197] The MFR (190 ≤, 2.16 kg) of ultra-low density polyethylene is 1.7 g / 10 min, and its density is 0.901 g / cm³. 3 Molecular weight distribution 5.0, hexene molar content 8.5 mol%, branch number 17.7 / 1000C. Thermal fractionation (SSA) analysis showed that the mass percentage of lamellar crystals with a thickness less than 6.2 nm was 8.0%; 48 parts.

[0198] Polytetrafluoroethylene (PTFE) with a molecular weight of 8000 and a particle size of 1.3 μm; 9 parts.

[0199] Polyethylene glycol molecular weight 6000; 1.2 parts.

[0200] The inner layer consists of the following components in parts by weight:

[0201] Metallocene linear polyethylene (same as outer layer); 90 parts.

[0202] Ultra-low density polyethylene (same as intermediate layer); 10 parts.

[0203] TiO2 masterbatch; 1.4 parts

[0204] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1.25:1.5:1, and the performance test results are shown in Table 1.

[0205] Example 6

[0206] The FFS heavy packaging film provided in this embodiment comprises three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are the same as in Example 1, except that the density of the linear low-density polyethylene in the middle layer is 0.93 g / cm³. 3 This is not within the preferred scope of the present invention.

[0207] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:2:1, and the performance test results are shown in Table 1.

[0208] Example 7

[0209] The FFS heavy packaging film provided in this embodiment comprises three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are the same as in Example 1, except that the density of the ultra-low density polyethylene in the middle layer is 0.905 g / cm³. 3 This is not within the preferred scope of the present invention.

[0210] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:2:1, and the performance test results are shown in Table 1.

[0211] Example 8

[0212] The FFS heavy packaging film provided in this embodiment includes three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are the same as in Embodiment 1. The difference is that the thickness ratio of the outer layer, the middle layer, and the inner layer of the FFS heavy packaging film provided in this embodiment is 1:0.8:1, which is not within the preferred range of this invention. The performance test results are shown in Table 1.

[0213] Comparative Example 1

[0214] The FFS heavy packaging film provided in this embodiment includes three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are the same as in Example 1. The difference is that the middle layer is made of 65 parts of linear low-density polyethylene, which is not within the preferred range of this invention.

[0215] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:2:1, and the performance test results are shown in Table 1.

[0216] Comparative Example 2

[0217] The FFS heavy packaging film provided in this embodiment includes three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are the same as in Example 1. The difference is that the middle layer is made of 36 parts of ultra-low density polyethylene, which is not within the preferred range of this invention.

[0218] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:2:1, and the performance test results are shown in Table 1.

[0219] Comparative Example 3

[0220] The FFS heavy packaging film provided in this embodiment includes three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are the same as in Example 1. The difference is that the middle layer contains 12 parts of polytetrafluoroethylene, which is not within the preferred range of this invention.

[0221] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:2:1, and the performance test results are shown in Table 1.

[0222] Comparative Example 4

[0223] The FFS repackaging film provided in this embodiment includes three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are the same as in Example 1, except that the middle layer contains 2.7 parts of polyethylene glycol, which is not within the preferred range of this invention.

[0224] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:2:1, and the performance test results are shown in Table 1.

[0225] Comparative Example 5

[0226] The FFS heavy packaging film provided in this embodiment includes three parts arranged sequentially from the outside to the inside: an outer layer, a middle layer, and an inner layer. The raw materials and their proportions for each layer are the same as in Example 1, except that polytetrafluoroethylene is not added to the middle layer.

[0227] The thickness ratio of the outer, middle, and inner layers of the FFS heavy packaging film provided in this embodiment is 1:2:1, and the performance test results are shown in Table 1.

[0228] Table 1

[0229]

[0230]

[0231] A comparison of the test results of the examples and comparative examples shows that, as long as the polytetrafluoroethylene treated in the examples is within the proportion of the present invention, the tear resistance of the film is improved, the processing efficiency of the film is improved, and the overall performance of the film is excellent.

[0232] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A membrane composition, characterized in that, The composition comprises: 40-60 parts by weight of linear low-density polyethylene, 40-60 parts by weight of ultra-low-density polyethylene, 5-10 parts by weight of polytetrafluoroethylene, and 1-2.5 parts by weight of polyethylene glycol. The polytetrafluoroethylene is treated with a modifier. The method for treating polytetrafluoroethylene with a modifier includes: impregnation in the presence of the modifier, washing, solid-liquid separation, and drying. The modifier is selected from at least one of tribosamethyl ethyl ether, tetrahydrofuran, dioxane, isopropanol and chloroform; The drying conditions include: temperature 55-85℃; time 20-30h; The conditions for the impregnation treatment include: temperature -5℃ to -10℃; time 5-10 min.

2. The composition according to claim 1, wherein, In the composition, the linear low-density polyethylene has a density of 0.92-0.93 g / cm³. 3 ; and / or The density of ultra-low density polyethylene is 0.885-0.909 g / cm³. 3 .

3. The composition according to claim 2, wherein, In the composition, the linear low-density polyethylene has a density of 0.923-0.926 g / cm³. 3 ; and / or The density of ultra-low density polyethylene is 0.886-0.903 g / cm³. 3 .

4. The composition according to claim 1, wherein, The linear low-density polyethylene has a melt flow rate of 3.1-4.0 g / 10 min at 190℃ / 2.16 kg; and / or The ultra-low density polyethylene has a melt flow rate of 0.8-3.2 g / 10 min at 190℃ / 2.16 kg, a molecular weight distribution of 3.8-5.0, and, according to thermal grading analysis, a mass percentage of lamellar crystals with a thickness less than 6.2 nm is 7.1-8.9%, with a branching number of 17.1-18.0 / 1000℃; and / or The polytetrafluoroethylene has a molecular weight of 6000-8000 and a particle size of 0.5-2μm; and / or The polyethylene glycol has a molecular weight of 2000-6000; and / or The ultra-low density polyethylene contains structural unit a provided by ethylene monomer and structural unit b provided by comonomer; and / or The comonomer is selected from at least one of propylene, butene, hexene, and octene.

5. The composition according to claim 4, wherein, The linear low-density polyethylene has a melt mass flow rate of 3.2-3.6 g / 10 min at 190℃ / 2.16 kg; and / or The ultra-low density polyethylene has a melt flow rate of 1.5-2.1 g / 10 min at 190℃ / 2.16 kg, and the mass percentage of lamellar crystals with a thickness of less than 6.2 nm, as determined by thermal grading analysis, is 7.5-8.5%; and / or The molar content of the ultra-low density polyethylene structural unit b is 8-10 mol%; and / or The comonomer is hexene.

6. The membrane composition according to claim 1, wherein, The modifier is selected from a mixture of tetrahydrofuran and isopropanol; and / or The washing is performed using an organic solvent selected from propanol and / or acetone.

7. The membrane composition according to claim 6, wherein, The mass ratio of tetrahydrofuran to isopropanol in the modifier is (7-9):(1-2.5). and / or The organic solvent is acetone.

8. Use of any one of the membrane compositions of claims 1-7 in the preparation of a membrane interlayer.

9. The application according to claim 8, wherein, The intermediate layer of the film is the intermediate layer of FFS heavy packaging film.

10. An interlayer material for membranes, said interlayer material being formed from raw materials comprising the composition of any one of claims 1-7.

11. An FFS repackaging film, wherein the intermediate layer of the FFS repackaging film contains the intermediate layer material of claim 10.

12. The FFS repackaging film according to claim 11, wherein, The FFS repackaging film comprises an outer layer, an inner layer, and the intermediate layer; and / or The FFS heavy packaging film has a thickness of ≤118μm, tear resistance of ≥35N, drop impact strength of ≥800g, can reduce the film heat sealing temperature by ≤120℃ during use, has a packaging capacity of ≥950 bags / hour, a heat seal strength of ≥47N / 15mm at 160℃, and a recovery rate of ≥87%.

13. The FFS repackaging film according to claim 12, wherein, The thickness ratio of the three composite structures—outer layer, middle layer, and inner layer—is (1-2.0):(1-2.0):

1.

14. The FFS repackaging film according to claim 12, wherein, The outer layer contains: Metallocene linear polyethylene: 70-90 parts by weight; Ultra-low density polyethylene: 10-30 parts by weight; Polyethylene glycol (PEG): 0.2-1.0 parts by weight; and / or The inner layer contains: Metallocene linear polyethylene: 70-90 parts by weight; Ultra-low density polyethylene: 10-30 parts by weight; TiO2 masterbatch: 1-3 parts by weight.

15. The FFS repackaging film according to claim 14, wherein, The physicochemical properties of the metallocene linear polyethylene in the inner and outer layers include: The melt mass flow rate at 190℃ / 2.16kg is 2.02-3.2g / 10min; and / or Its density is 0.920-0.935 g / cm³. 3 ; and / or Molecular weight distribution 3.3-3.8, weight average molecular weight 120,000-160,000; and / or Crystallization thermal grading analysis showed that the relative content of lamellar crystals with a thickness of 9.6 nm or more was 12-16% or more; and / or The number of branches is 11.8-13.5 / 1000C.

16. The FFS repackaging film according to claim 15, wherein, The physicochemical properties of the metallocene linear polyethylene in the inner and outer layers include: The melt mass flow rate at 190℃ / 2.16kg is 2.02-2.23g / 10min; and / or Its density is 0.921-0.930 g / cm³. 3 ; and / or Weight-average molecular weight of 130,000-150,000; and / or Crystallization thermal grading analysis showed that the relative content of lamellar crystals with a thickness of 9.6 nm or more was 13-15%.

17. The FFS repackaging film according to claim 14, wherein, In the outer layer, the physicochemical parameters of the ultra-low density polyethylene include: The melt mass flow rate at 190℃ / 2.16kg is 0.5g / 10-2.5g / 10min; and / or Its density is 0.908-0.915 g / cm³. 3 ; and / or Molecular weight distribution 3.8–4.1; and / or Crystallization thermal grading analysis showed that the mass percentage of 9.4 nm thick lamellar crystals was 8.0-9.2%; and / or Branch count 14.5-17.0 / 1000C; and / or The ultra-low density polyethylene contains structural unit a provided by ethylene monomer and structural unit b provided by comonomer; and / or The comonomer is selected from at least one of propylene, butene, hexene, and octene; and / or The polyethylene glycol has a molecular weight of 2000-6000; and / or In the inner layer, the physicochemical parameters of the ultra-low density polyethylene include: The melt mass flow rate at 190℃ / 2.16kg is 0.8-3.2g / 10min; and / or Molecular weight distribution 3.8–5.0; and / or Crystallization thermal grading analysis showed that the mass percentage of lamellar crystals with a thickness of less than 6.2 nm was 7.1-8.9%; and / or Branch number 17.1-18.0 / 1000C.

18. The FFS repackaging film according to claim 17, wherein, In the outer layer, the physicochemical parameters of the ultra-low density polyethylene include: The melt mass flow rate at 190℃ / 2.16kg is 0.8-1.6g / 10min; and / or Its density is 0.909-0.912 g / cm³. 3 ; and / or Crystallization thermal grading analysis showed that the mass percentage of 9.4 nm thick lamellar crystals was 8.5-8.9%; and / or The molar content of the ultra-low density polyethylene structural unit b is 4.2-5.5%; and / or The comonomer is hexene; and / or In the inner layer, the physicochemical parameters of the ultra-low density polyethylene include: The melt mass flow rate at 190℃ / 2.16kg is 0.886-0.903 g / cm³. 3 ; and / or Crystallization thermal grading analysis showed that the mass percentage of lamellar crystals with a thickness of less than 6.2 nm was 7.5-8.5%.

Images