A method for producing a packing tape using printed waste film

Abstract

This invention discloses a method for preparing packing straps using waste PET printing film, relating to the field of packing strap technology. In this method, waste PET printing film is processed to obtain basic raw materials with specific physical properties, which are then melt-extruded by a screw extruder with specific parameters, stretched, and shaped to obtain packing straps. The raw material formulation of the packing strap is as follows: based on 100 parts of the basic raw material, the packing strap also includes the following modified auxiliary materials: by weight percentage of the basic raw material, ABS 8-14%, maleic anhydride-grafted PET 4-6%, modifier 4-8%, modified silica 8-12%, antioxidant 0.2-0.4%, and lubricant 0.15-0.3%. In this invention, the physical properties of the basic raw material and the operating parameters of the screw extruder are highly compatible, thereby maximizing the obtain of the best-performing melt, and with the synergistic effect of the relevant modified auxiliary materials, packing straps with excellent comprehensive performance are prepared.

Description

Technical Field

[0001] This invention relates to the field of packing tape technology, specifically a method for preparing packing tape using waste printed film. Background Technology

[0002] PET (polyethylene terephthalate) is a linear thermoplastic resin and one of the most widely used engineering plastics. It is a high-value resin that combines a transparent and high-gloss appearance with excellent weather resistance and chemical stability. It also has excellent impact resistance, creep resistance, dimensional stability, and heat resistance.

[0003] As a core consumable in the logistics and packaging sectors, PET has become the mainstream choice for strapping due to its superior performance. However, its production largely relies on virgin PET resin, resulting in high raw material costs and the consumption of petrochemical resources. Meanwhile, the printing industry generates a large volume of waste PET printing film. Using this waste PET film as a raw material for strapping production can undoubtedly reduce costs significantly and generate substantial profits.

[0004] While the recycling of PET waste is widespread in current technologies, and there have been attempts to use it to produce strapping, suitable processes for PET printing waste film are not common. Furthermore, the mismatch between extrusion equipment parameters, temperature control processes, and the characteristics of recycled raw materials easily leads to problems such as feed bridging, melt foaming, and thermal degradation of molecular chains. At the same time, simple modification methods involving the addition of conventional additives cannot simultaneously guarantee the mechanical properties and weather resistance of the strapping, failing to meet the needs of practical industrial applications.

[0005] Therefore, the present invention provides a method for preparing packing tape using waste printed film, which is of great significance. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing packing tape using waste printed film, so as to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing packing straps using waste printed film includes the following steps: Step 1: Waste PET printing film is crushed, impurities removed, dried, and purified to obtain basic raw materials with specific physical characteristics; Step 2: The basic raw materials are fed into a screw extruder with specific parameters using a forced feeder, then melt-extruded, stretched and shaped, cooled, and wound to obtain the packing strap; Furthermore, the specific physical properties refer to: controlling the moisture content of the basic raw materials to ≤0.50% and the bulk density to ≥0.55g / cm³. 3 The bulk density is ≤3.50, and the intrinsic viscosity is ≥0.85dL / g; where bulk density = bulk volume / compacted volume.

[0008] The moisture content of the base raw materials must be ≤0.50% to avoid air bubbles during melting, ensuring the continuity of the melt and the strength of the finished product; the bulk density must be ≥0.55g / cm³. 3 Only with a high compression ratio screw can the feeding requirements of this invention be met; a bulkiness of ≤3.50 is necessary to adapt to the design of a large thread groove depth in the feeding section, avoiding bridging and material breakage during feeding; and the raw material has no risk of molecular chain degradation at an intrinsic viscosity of 0.85~0.95dL / g, which can ensure the mechanical properties and weather resistance of the subsequent finished product.

[0009] Furthermore, the specific parameters refer to: the screw extruder adopts a large screw diameter structure, with a screw diameter of 300~350mm; a large thread groove depth feeding section structure, with a feeding section groove depth of 70~80mm; a high compression ratio compression section structure, with a compression ratio of (55~65):1; a metering section structure combining constant depth variable pitch and constant depth equal pitch, with a metering section groove depth of 15~25mm, a feed section pitch of 40~50mm, and a discharge section pitch of 12~18mm; a screw length-to-diameter ratio of (30~40):1; an operating current of 275~285A; a screw speed of 8~35rpm; and an extrusion pressure of 3~5MPa.

[0010] Furthermore, the large screw diameter structure ensures high production output; the large thread groove deep feeding section structure is suitable for fluffy film sheets; the high compression ratio compression section structure can gradually compact the material and increase the bulk density; the constant depth variable pitch and constant depth equal pitch combined metering section structure can realize the homogenization and mixing of the melt.

[0011] The feeding section features a deep spiral groove design, which is more suitable for loose raw materials, enabling efficient feeding and avoiding problems such as bridging and shaft seizure. It is also better suited to the operating conditions of the screw extruder used in this invention under a stable current of 275~285A. The compression section employs a high compression ratio structure, which can gradually compress the raw material, increasing the internal bulk density and preparing for subsequent melting. The metering section uses a combination of constant depth variable pitch and constant depth equal pitch structures to maximize the uniform mixing of the melt and avoid localized thermal degradation.

[0012] Furthermore, the screw extruder adopts a three-stage temperature gradient temperature control process, specifically: the feeding section is gradually cooled from a high temperature zone of 295~305℃ to a medium temperature zone of 275~285℃, the compression section is gradually cooled from a medium temperature zone of 275~285℃ to a uniform temperature zone of 260±2℃, and the metering section is kept constant in a uniform temperature zone of 260±2℃.

[0013] To address the characteristic that the melting point of waste PET printing film is around 260℃, this invention employs a three-stage temperature gradient control process for its melting treatment. In the feeding stage, the base material is rapidly heated to soften it, achieving efficient feeding and initial plasticization, and avoiding blockage by cold material. Subsequently, the material is gradually cooled and compressed to ensure that excessive heat history is suppressed while melting progresses, preventing the breakage of the raw material molecular chains. Finally, isothermal homogenization is performed to stabilize the temperature and viscosity of the melt, avoiding local overheating and degradation.

[0014] Furthermore, the default feeding mode of the forced feeder is intermittent feeding mode, and its rotation speed is the same as that of the screw extruder.

[0015] Furthermore, during the production of strapping, the parameters of the forced feeder and screw extruder can be adaptively adjusted according to the actual physical properties of the basic raw materials. Specifically: If the bulkiness of the base material deviates, i.e., the bulkiness is >3.50, switch the feeding mode of the forced feeder to continuous, and increase the temperature of the feed inlet of the screw extruder compression section by 3~5℃. If the working current of the screw extruder is too high at this time, i.e. the working current is continuously >285A, then reduce the screw speed by 2~3%, and restore the screw speed after it stabilizes. If the moisture content of the base raw material deviates, i.e., the moisture content is >0.50%, reduce the feed inlet temperature of the screw extruder feeding section by 4~6℃ and the speed of the forced feeder by 3~5%. If the intrinsic viscosity of the base material deviates, i.e., intrinsic viscosity < 0.85 dL / g, reduce the screw speed of the screw extruder by 2-3% and the temperature of the entire working section by 2-3°C.

[0016] If the bulkiness of the base material is greater than 3.50, material accumulation or jamming may occur in the feeding section of the screw extruder. Accumulation and jamming can lead to excessive compression of the melt inside the screw extruder, thus increasing the extrusion pressure. Furthermore, accumulation and jamming can cause bridging in the screw extruder, which in turn causes significant fluctuations in the feed rate and speed, resulting in insufficient material or overload, and consequently, large fluctuations in the operating current. In short, the stability of the entire "feed-melt-extrusion" process is disrupted. Therefore, it is necessary to adjust the feeding mode of the forced feeder to a smoother continuous feeding mode, while simultaneously increasing the inlet temperature of the compression section to soften large pieces of material more thoroughly and avoid localized overload. Temporarily reducing the screw speed can slow down the screw feeding rate, ensuring sufficient time for material delivery while preventing material accumulation and jamming.

[0017] If the moisture content of the base raw material is greater than 0.50%, the moisture in the raw material will rapidly vaporize, causing bubbles to form in the melt. This will disrupt the homogeneity of the melt, increase the workload of the screw extruder, and lead to fluctuations in relevant parameters, such as increased current and pressure, and decreased intrinsic viscosity. Therefore, it is necessary to lower the inlet temperature of the screw extruder's feeding section to reduce melt bubbles caused by moisture vaporization; at the same time, reduce the speed of the forced feeder to prolong the residence time of the raw material in the feeding section, assisting in moisture escape and further reducing moisture content.

[0018] If the intrinsic viscosity of the melt is <0.85 dL / g, the melt viscosity is insufficient, leading to a decrease in the tensile strength of the prepared packing tape. The reasons for this include: excessively high temperatures in various operating sections of the screw extruder, excessive heating of the base material within the screw, and excessive shearing of the melt by the screw, causing mechanical damage to the molecular chains. These combined factors result in molecular weight fragmentation of the melt, leading to insufficient melt viscosity. Therefore, it is necessary to reduce the temperature of all operating sections of the screw extruder and the screw speed in this case.

[0019] Furthermore, the stretching and shaping parameters are as follows: first stretching 1.5 to 2 times at 70 to 90°C, then stretching 3 to 4 times at 100 to 120°C, and finally holding at 130 to 150°C for 30 to 90 seconds.

[0020] Furthermore, relevant modified auxiliary materials are added to the raw material components of the packing tape; Based on 100 parts of basic raw materials, the packing strap also includes the following modified auxiliary materials: by the mass percentage of basic raw materials, ABS 8~14%, maleic anhydride grafted PET 4~6%, modifier 4~8%, modified silica 8~12%, antioxidant 0.2~0.4%, and lubricant 0.15~0.3%.

[0021] Furthermore, the maleic anhydride-grafted PET is prepared according to the maleic anhydride-grafted PET preparation method disclosed in the prior art CN114921092A "A Nylon Composition and Its Preparation Method and Application".

[0022] To improve the mechanical properties of the packing straps, this invention introduces ABS to toughen and modify PET waste; however, the two have poor compatibility, so maleic anhydride-grafted PET is further introduced for improvement.

[0023] Furthermore, the method for preparing the modifier is as follows: (1) Under nitrogen protection, 1-thioglycerol, 2-hydroxy-4-propenoxybenzophenone and polymerization inhibitor were added to acetone, stirred and mixed, and then azobisisobutyronitrile was added. The mixture was stirred and reacted at 55~65℃ for 2~4h. The reaction was stopped and the UV modifier was obtained by vacuum distillation. (2) Under nitrogen protection, triphenylmethane triisocyanate, dibutyltin dilaurate and polymerization inhibitor are added to acetone and stirred until well mixed. Then, allyl hydroxyethyl ether is slowly added to it and the addition is completed within 30 to 60 minutes. At the same time, the mixture is stirred at 45 to 55°C for 30 to 60 minutes. Then, the temperature is raised to 75 to 85°C and stirred for 1 to 3 hours to obtain diisocyanate containing double bonds. (3) Add UV modifier to the reaction system in (2), continue stirring at 75~85℃ for 4~8h, end the reaction, and obtain the modifier by vacuum distillation.

[0024] Furthermore, the molar ratio of 1-thioglycerol and 2-hydroxy-4-propenoxybenzophenone is (1.05~1.1):1.

[0025] Further, in step (1), the amount of the polymerization inhibitor added is 0.05~0.1% of the mass of 2-hydroxy-4-propenoxybenzophenone added.

[0026] Furthermore, the amount of azobisisobutyronitrile added is 1.5 to 2.5% of the mass of 1-thioglycerol added.

[0027] Furthermore, the molar ratio of the triphenylmethane triisocyanate, allyl hydroxyethyl ether, and UV modifier is 2:2:1.

[0028] Furthermore, the amount of dibutyltin dilaurate added is 0.5-1% of the total mass of the reactants; wherein the reactants are triphenylmethane triisocyanate, allyl hydroxyethyl ether, and UV modifier.

[0029] Further, in step (2), the amount of the polymerization inhibitor added is 0.05~0.1% of the mass of allyl hydroxyethyl ether added.

[0030] This invention first prepares a UV modifier by reacting the mercapto group of 1-thioglycerol with the double bond of 2-hydroxy-4-propenoxybenzophenone. Then, by controlling the molar ratio of triphenylmethane triisocyanate and allyl hydroxyethyl ether to 1:1, one isocyanate group of triphenylmethane triisocyanate reacts with the hydroxyl group of allyl hydroxyethyl ether to prepare a diisocyanate containing a double bond. Finally, by again controlling the molar ratio, the UV modifier reacts with the diisocyanate containing a double bond to prepare the modifier. The modifier contains two double bonds, two isocyanate groups, and a benzophenone structure. The double bonds can undergo melt grafting with ABS, achieving a chemical bond between the modifier and ABS. The isocyanate groups can react with the hydroxyl and carboxyl groups at the ends of the PET molecular chain, acting as chain extenders. Overall, this results in longer PET molecular chains and tighter entanglement, significantly improving the mechanical properties of the packing tape. The benzophenone structure absorbs ultraviolet light, giving PET resistance to UV aging.

[0031] Furthermore, the method for preparing the modified silica is as follows: (1) Add vinyltriethoxysilane to an 80-90 wt% aqueous ethanol solution, and add acetic acid to adjust the pH to 4.8-5.2. Stir and mix at 45-55℃ for 30-60 min to obtain a vinylsilane hydrolysate; add 3-aminopropyltriethoxysilane to an 80-90 wt% aqueous ethanol solution, and add acetic acid to adjust the pH to 4.8-5.2. Stir and mix at 45-55℃ for 30-60 min to obtain an aminosilane hydrolysate; (2) Place the silica under vacuum drying at 110~120℃ for 1~2h, then add it to a high-speed mixer, and under nitrogen protection, add vinyl silane hydrolysate and amino silane hydrolysate in the form of spray, while stirring and mixing at 70~80℃ for 1~2h to obtain silane modified silica. (3) Under nitrogen protection, silane-modified silica and methylcyclohexane diisocyanate were added to acetone and stirred at 75-85°C for 1-2 hours. After separation and purification, modified silica was obtained.

[0032] Furthermore, the volume ratio of the vinyltriethoxysilane to the aqueous ethanol solution is (0.4~0.8):10.

[0033] Furthermore, the volume ratio of the 3-aminopropyltriethoxysilane to the aqueous ethanol solution is (0.4~0.8):10.

[0034] Furthermore, the ratio of the silicon dioxide, vinylsilane hydrolysate, and aminosilane hydrolysate is 1g:(0.2~0.3)mL:(0.2~0.3)mL.

[0035] Furthermore, the mass ratio of the silane-modified silica to the methylcyclohexane diisocyanate is (18~22):1.

[0036] In this invention, vinyltriethoxysilane and 3-aminopropyltriethoxysilane are used to modify silica to obtain silane-modified silica containing vinyl and amino groups. Further modification of the silane-modified silica with methylcyclohexane diisocyanate yields silica containing double bonds and isocyanate groups. Similarly, the double bonds can undergo melt grafting with ABS, achieving a chemical bond between the modified silica and ABS. The isocyanate groups can react with the hydroxyl and carboxyl groups at the ends of the PET molecular chain. With the introduction of modified silica, the modified silica significantly improves the mechanical properties of the packing strap through both physical reinforcement and chemical cross-linking. Furthermore, silica also exhibits a certain degree of UV aging resistance.

[0037] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) By using waste PET printing film to prepare packing tape, the resource utilization of waste has been realized.

[0038] (2) Through customized melt extrusion process, deep adaptation and synergistic effect of physical properties of basic raw materials, efficient and stable processing of PET printing waste film is achieved, which clears the obstacles at the melt level for the subsequent performance of modified auxiliary materials. This is the premise and foundation for the preparation of packing tape with excellent comprehensive performance in this invention.

[0039] (3) With the further synergistic effect of ABS, maleic anhydride grafted PET, modifier and modified silica, the mechanical properties of the packing strap are further improved, and it is also endowed with excellent anti-ultraviolet aging ability, which greatly improves the applicability and durability of the packing strap. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that the following quantities are by weight, and there are no special restrictions on the suppliers of all raw materials involved in this invention. Exemplary examples include: In the following embodiments, after PET printing waste film was crushed, impurities removed, dried, and purified, the basic raw materials were tested according to the relevant test methods and regulations in GB / T 17932-2013, GB / T 14190-2017, and GB / T 6283-2008 standards. The test results are shown in Table 1 below: Table 1. Test results of PET printing waste film as basic raw material

[0042] Maleic anhydride-grafted PET was prepared according to the method disclosed in CN114921092A "A Nylon Composition and Its Preparation Method and Application", with a maleic anhydride grafting rate of 1.2 wt%. ABS, model HF-681; antioxidant 1010; stearic acid; 1-thioglycerol, CAS number 96-27-5; 2-hydroxy-4-propenoxybenzophenone, CAS number 2549-87-3; polymerization inhibitor 701; triphenylmethane triisocyanate, CAS number 2422-91-5; dibutyltin dilaurate; silicon dioxide, particle size 20~40nm; vinyltriethoxysilane; 3-aminopropyltriethoxysilane; 1610 type packing strap dimensions: width 16.00±0.05mm, thickness 1.00±0.01mm; and other raw materials are commercially available; each part by weight is 100g.

[0043] Example 1: A method for preparing packing straps using waste printed film: S1: 100 qualified basic raw materials are added to the screw extruder using a forced feeder, and after melt extrusion, stretching and shaping, cooling and winding, 1610 type strapping is obtained; The forced feeder uses an intermittent feeding mode with a speed of 20 rpm; the screw extruder is 11 m long, 320 mm in diameter, and has a length-to-diameter ratio of 34.375:1; the feeding section has a groove depth of 75 mm; the compression section has a compression ratio of 60:1; the metering section has a groove depth of 20 mm; the feed section has a screw pitch of 45 mm; and the discharge section has a screw pitch of 15 mm; the extrusion pressure is 4 MPa; the operating current is 280 A; and the screw speed is 20 rpm; the temperatures of each working section are as follows: the feeding section gradually decreases from 300℃ to 280℃; the compression section gradually decreases from 280℃ to 260℃; and the metering section is kept constant at 260℃. The stretching and setting parameters are as follows: stretch twice at 80℃, then stretch four times at 110℃, and then heat set at 140℃ for 60 seconds.

[0044] Based on Example 1, a control experiment was conducted, setting up Comparative Example 1, as follows: Comparative Example 1: A method for preparing packing straps using waste printed film: Comparative Example 1 uses a conventional SKR-SJ90 single-screw extruder to melt and extrude the base material. The relevant parameters are as follows: motor power is 132kW, screw diameter is 90mm, length-to-diameter ratio is 33:1, compression ratio is 5:1, speed is 20rpm, and the temperature of each working section is as follows: the feeding section is gradually cooled from 300℃ to 280℃, the compression section is gradually cooled from 280℃ to 260℃, and the metering section is kept constant at 260℃; other processes remain unchanged.

[0045] Performance Test 1: The packing straps prepared in Example 1 and Comparative Example 1 were tested for appearance quality, dimensional error, mechanical properties, and UV aging resistance. The specific test results are shown in Table 2 below: Table 2 Comparison of test results of the packing tapes prepared in Example 1 and Comparative Example 1

[0046] Result Analysis 1: As can be seen from the test results in Table 2 above, Example 1 of the present invention uses a screw extruder with specific parameters and raw materials with specific physical properties to comprehensively prepare a packing strap with small dimensional error, excellent appearance quality and mechanical properties; however, the packing strap has poor resistance to ultraviolet aging, and its tensile strength drops sharply after ultraviolet aging.

[0047] To improve the overall performance of the packing straps, the following examples, based on Example 1, are further supplemented with Examples 2 to 4, as detailed below: Example 2: A method for preparing packing straps using waste printed film: Example 2 is based on Example 1, with the following adjustments: relevant modified excipients were added, while other processes remained unchanged. Specifically: S1: Prepare modified excipients: S11: Preparation of the modifier: (1) Under nitrogen protection, 1.07 mol (approximately 115.731 g) of 1-thioglycerol, 1 mol (254.28 g) of 2-hydroxy-4-propenoxybenzophenone, and 0.19 g of polymerization inhibitor 701 were added to 2 L of acetone, stirred and mixed, and then 2.32 g of azobisisobutyronitrile was added. The mixture was stirred and reacted at 60 °C for 3 h. The reaction was then stopped, and the UV modifier was obtained by vacuum distillation; (2) Under nitrogen protection, 2 mol (734.72 g) of triphenylmethane triisocyanate, 9.7 g of acetone, and 1 mol (approximately 115.731 g) of 1-thioglycerol, 1 mol (254.28 g) of 2-hydroxy-4-propenoxybenzophenone, and 0.19 g of polymerization inhibitor 701 were added to 2 L of acetone, stirred and mixed, and then 2.32 g of azobisisobutyronitrile was added. The mixture was stirred and reacted at 60 °C for 3 h. The reaction was then stopped, and the UV modifier was obtained by vacuum distillation; 6g of dibutyltin dilaurate and 0.153g of polymerization inhibitor 701 were added to 4L of acetone and stirred until mixed. Then, 2mol (204.26g) of allyl hydroxyethyl ether was slowly added to it and the addition was completed within 45min. At the same time, the mixture was stirred at 50℃ for 45min and then heated to 80℃ and stirred for 2h to obtain diisocyanate containing double bonds. (3) 1mol (362.44g) of UV modifier was added to the reaction system in (2) and the mixture was stirred at 80℃ for 6h to end the reaction. The modifier was obtained by vacuum distillation. S12: Preparation of modified silica: (1) Add vinyltriethoxysilane to 85wt% ethanol solution, and add acetic acid to adjust the pH to 5.0. Stir and mix at 50℃ for 45min to obtain vinylsilane hydrolysate; add 3-aminopropyltriethoxysilane to 85wt% ethanol solution, and add acetic acid to adjust the pH to 5.0. Stir and mix at 50℃ for 45min to obtain aminosilane hydrolysate. The volume ratio of vinyltriethoxysilane to ethanol solution is 0.6:10, and the volume ratio of 3-aminopropyltriethoxysilane to ethanol solution is 0.6:10; (2) Add 1400g silica Place it under vacuum drying at 115℃ for 1.5h, then add it to a high-speed mixer, and under nitrogen protection, add vinyl silane hydrolysate and amino silane hydrolysate in the form of spray, and stir and mix at 75℃ for 1.5h to obtain silane modified silica, wherein the ratio of silica, vinyl silane hydrolysate and amino silane hydrolysate is 1g:0.25mL:0.25mL; (3) Under nitrogen protection, add 1400g of silane modified silica and 70g of methylcyclohexane diisocyanate to 2.5L of acetone, stir and react at 80℃ for 1.5h, and after separation and purification, obtain modified silica; S2: Add 100 parts of qualified basic raw materials, 10 parts of ABS, 5 parts of maleic anhydride grafted PET, 6 parts of modifier, 10 parts of modified silica, 0.3 parts of antioxidant 1010, and 0.25 parts of stearic acid to a high-speed mixer. After stirring and mixing at 90°C for 15 minutes, add the mixture to a screw extruder using a forced feeder. After melt extrusion, stretching and shaping, cooling, and winding, obtain type 1610 strapping.

[0048] Example 3: A method for preparing packing straps using waste printed film: Example 3 is based on Example 2, with the following adjustment: the proportion of raw material components in the packing tape is changed, while other processes remain unchanged. Specifically: S2: Add 100 parts of qualified basic raw materials, 8 parts of ABS, 4 parts of maleic anhydride grafted PET, 4 parts of modifier, 8 parts of modified silica, 0.3 parts of antioxidant 1010, and 0.25 parts of stearic acid into a high-speed mixer. After stirring and mixing at 90°C for 15 minutes, add the mixture into a screw extruder using a forced feeder. After melt extrusion, stretching and shaping, cooling, and winding, obtain type 1610 strapping.

[0049] Example 4: A method for preparing packing straps using waste printed film: Example 4 is based on Example 2, with the following adjustment: the proportion of raw material components in the packing tape is changed, while other processes remain unchanged. Specifically: S2: Add 100 parts of qualified basic raw materials, 14 parts of ABS, 6 parts of maleic anhydride grafted PET, 8 parts of modifier, 12 parts of modified silica, 0.3 parts of antioxidant 1010, and 0.25 parts of stearic acid into a high-speed mixer. After stirring and mixing at 90°C for 15 minutes, add the mixture into a screw extruder using a forced feeder. After melt extrusion, stretching and shaping, cooling, and winding, 1610 type strapping tape is obtained.

[0050] Further, based on Example 2, control experiments were conducted, setting up comparative examples 2 to 6, as detailed below: Comparative Example 2: A method for preparing packing straps using waste printed film: Comparative Example 2 is based on Example 2, with the following adjustments: ABS and maleic anhydride-grafted PET are not added, while other processes remain unchanged. Specifically: S2: Add 100 parts of qualified basic raw materials, 6 parts of modifier, 10 parts of modified silica, 0.3 parts of antioxidant 1010, and 0.25 parts of stearic acid to a high-speed mixer. Stir and mix at 90°C for 15 minutes, then feed the mixture into a screw extruder using a forced feeder. After melt extrusion, stretching and shaping, cooling, and winding, 1610 type strapping tape is obtained.

[0051] Comparative Example 3: A method for preparing packing straps using waste printed film: Comparative Example 3 is based on Example 2, with the following adjustments: no modifier was added, while other processes remained unchanged. Specifically: S2: Add 100 parts of qualified basic raw materials, 10 parts of ABS, 5 parts of maleic anhydride grafted PET, 10 parts of modified silica, 0.3 parts of antioxidant 1010, and 0.25 parts of stearic acid to a high-speed mixer. After stirring and mixing at 90°C for 15 minutes, add the mixture to a screw extruder using a forced feeder. After melt extrusion, stretching and shaping, cooling, and winding, obtain type 1610 strapping.

[0052] Comparative Example 4: A method for preparing packing straps using waste printed film: Comparative Example 4 is based on Example 2, with the following adjustments: no modified silica is added, while other processes remain unchanged. Specifically: S2: Add 100 parts of qualified basic raw materials, 10 parts of ABS, 5 parts of maleic anhydride grafted PET, 6 parts of modifier, 0.3 parts of antioxidant 1010, and 0.25 parts of stearic acid to a high-speed mixer. Stir and mix at 90°C for 15 minutes, then feed the mixture into a screw extruder using a forced feeder. After melt extrusion, stretching and shaping, cooling, and winding, 1610 type strapping tape is obtained.

[0053] Comparative Example 5: A method for preparing packing straps using waste printed film: Comparative Example 5 is based on Example 2, with the following adjustment: a UV modifier is directly used to replace the modifier, while other processes remain unchanged. Specifically: S2: Add 100 parts of qualified basic raw materials, 10 parts of ABS, 5 parts of maleic anhydride grafted PET, 6 parts of UV modifier, 10 parts of modified silica, 0.3 parts of antioxidant 1010, and 0.25 parts of stearic acid into a high-speed mixer. After stirring and mixing at 90°C for 15 minutes, add the mixture into a screw extruder using a forced feeder. After melt extrusion, stretching and shaping, cooling, and winding, obtain type 1610 strapping.

[0054] Comparative Example 6: A method for preparing packing straps using waste printed film: Comparative Example 6 is based on Example 2, with the following adjustment: only vinyltriethoxysilane is used to modify silica, while other processes remain unchanged. Specifically: S12: Preparation of modified silica: (1) Add vinyltriethoxysilane to 85wt% ethanol solution, and add acetic acid to adjust the pH to 5.0. Stir and mix at 50℃ for 45min to obtain vinylsilane hydrolysate; (2) Place 1400g silica under vacuum drying at 115℃ for 1.5h, and then add it to a high-speed mixer. Under nitrogen protection, add vinylsilane hydrolysate in the form of spray, and stir and mix at 75℃ for 1.5h to obtain silane modified silica. The ratio of silica to vinylsilane hydrolysate is 1g:0.25mL; (3) Under nitrogen protection, add 1400g silane modified silica and 70g methylcyclohexane diisocyanate to 2.5L acetone, stir and react at 80℃ for 1.5h, and obtain modified silica after separation and purification.

[0055] Performance Test 2: The packing straps prepared in Examples 2-4 and Comparative Examples 2-6 were subjected to performance tests according to the test methods described in Performance Test 1 above. The specific test results are shown in Table 3 below: Table 3 Comparison of test results of packing tapes prepared in Examples 1-4 and Comparative Examples 2-6

[0056] Result Analysis 2: As can be seen from the test results in Table 3 above, Examples 2 to 4 of the present invention all exhibit excellent mechanical properties and UV aging resistance, indicating that the present invention, through the synergistic effect of ABS, maleic anhydride-grafted PET, modifier, and modified silica, enables the packing strap to have both excellent mechanical properties and UV aging resistance, and has better applicability. In Comparative Example 2, the absence of ABS and maleic anhydride-grafted PET affected the compatibility of the modifier, modified silica, and the PET matrix, leading to a significant decrease in the performance of the strapping. In Comparative Example 3, the lack of a modifier reduced the cross-linking degree of the strapping and resulted in poor improvement in its UV aging resistance. In Comparative Example 4, the absence of modified silica prevented effective improvement in mechanical properties, resulting in only a slight increase in tensile strength. In Comparative Example 5, the UV modifier lacked isocyanate groups and double bonds, preventing cross-linking with the PET matrix and ABS, thus reducing mechanical properties. However, due to the effect of the UV modifier, the strapping's UV aging resistance did not significantly decrease. In Comparative Example 6, the absence of amino groups on the silica prevented reaction with methylcyclohexane diisocyanate, thus introducing isocyanate groups onto the silica. This reduced the dispersibility of the modified silica, leading to a decrease in the mechanical properties of the strapping.

[0057] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing packing straps using waste printed film, characterized in that: Includes the following steps: Step 1: Waste printed film is crushed, impurities removed, dried, and purified to obtain basic raw materials with specific physical properties; The specific physical properties refer to: controlling the moisture content of the base raw materials to ≤0.50% and the bulk density to ≥0.55g / cm³. 3 Looseness ≤ 3.50, intrinsic viscosity ≥ 0.85 dL / g; Step 2: The basic raw materials are fed into a screw extruder with specific parameters using a forced feeder, then melt-extruded, stretched and shaped, cooled, and wound to obtain the packing strap; The specific parameters refer to: the screw extruder adopts a large screw diameter structure, with a screw diameter of 300~350mm; a large thread groove depth feeding section structure, with a feeding section groove depth of 70~80mm; a high compression ratio compression section structure, with a compression ratio of (55~65):1; a metering section structure combining constant depth variable pitch and constant depth equal pitch, with a metering section groove depth of 15~25mm, a feed section pitch of 40~50mm, and a discharge section pitch of 12~18mm; a screw length-to-diameter ratio of (30~40):1; an operating current of 275~285A; a screw speed of 8~35rpm; and an extrusion pressure of 3~5MPa.

2. The method for preparing packing straps using waste printing film according to claim 1, characterized in that: The deep feed section structure with large thread grooves is suitable for loose film and sheet materials; the high compression ratio compression section structure can gradually compact materials and increase bulk density; the constant depth variable pitch and constant depth equal pitch combined metering section structure can realize the homogenization and mixing of melts. The screw extruder adopts a three-stage temperature gradient temperature control process, specifically: the feeding section is gradually cooled from a high temperature zone of 295~305℃ to a medium temperature zone of 275~285℃, the compression section is gradually cooled from a medium temperature zone of 275~285℃ to a uniform temperature zone of 260±2℃, and the metering section is kept constant in a uniform temperature zone of 260±2℃.

3. The method for preparing packing straps using waste printing film according to claim 1, characterized in that: During the production of strapping, the parameters of the forced feeder and screw extruder can be adjusted adaptively according to the actual physical properties of the basic raw materials. Specifically: if the bulkiness of the base material deviates, switch the feeding mode of the forced feeder to increase the temperature of the feed inlet of the screw extruder compression section. If the operating current of the screw extruder is too high at this time, reduce the screw speed and restore the screw speed after it stabilizes. If the moisture content of the base material deviates, reduce the feed inlet temperature of the screw extruder feeding section and the speed of the forced feeder; If the intrinsic viscosity of the base material deviates, reduce the screw speed and the temperature of the entire operating section of the screw extruder.

4. The method for preparing packing straps using waste printing film according to claim 1, characterized in that: The raw material components of the packing strap also include relevant modified auxiliary materials; Based on 100 parts of basic raw materials, the packing strap also includes the following modified auxiliary materials: by the mass percentage of basic raw materials, ABS 8~14%, maleic anhydride grafted PET 4~6%, modifier 4~8%, modified silica 8~12%, antioxidant 0.2~0.4%, and lubricant 0.15~0.3%.

5. The method for preparing packing straps using waste printing film according to claim 4, characterized in that: The preparation method of the modifier is as follows: (1) Under nitrogen protection, 1-thioglycerol, 2-hydroxy-4-propenoxybenzophenone, polymerization inhibitor and azobisisobutyronitrile are added to acetone, stirred and reacted at 55~65℃, and distilled under reduced pressure to obtain the UV modifier; (2) Under nitrogen protection, triphenylmethane triisocyanate, allyl hydroxyethyl ether, dibutyltin dilaurate and polymerization inhibitor are added to acetone, stirred and reacted at 45~55℃, then heated to 75~85℃ and stirred and reacted, then the UV modifier is added to it, stirred and reacted at 75~85℃, and distilled under reduced pressure to obtain the modifier.

6. The method for preparing packing straps using waste printing film according to claim 5, characterized in that: The molar ratio of 1-thioglycerol and 2-hydroxy-4-propenoxybenzophenone is (1.05~1.1):1; in step (1), the amount of polymerization inhibitor added is 0.05~0.1% of the mass of 2-hydroxy-4-propenoxybenzophenone added; the amount of azobisisobutyronitrile added is 1.5~2.5% of the mass of 1-thioglycerol added; the molar ratio of triphenylmethane triisocyanate, allyl hydroxyethyl ether, and UV modifier is 2:2:1; the amount of dibutyltin dilaurate added is 0.5~1% of the total mass of reactants; wherein the reactants are triphenylmethane triisocyanate, allyl hydroxyethyl ether, and UV modifier; in step (2), the amount of polymerization inhibitor added is 0.05~0.1% of the mass of allyl hydroxyethyl ether added.

7. The method for preparing packing straps using waste printing film according to claim 4, characterized in that: The modified silica is prepared by: (1) adding vinyltriethoxysilane to an aqueous ethanol solution and adding acetic acid to adjust the pH to 4.8-5.2, stirring and mixing at 45-55°C to obtain a vinylsilane hydrolysate; adding 3-aminopropyltriethoxysilane to an aqueous ethanol solution and adding acetic acid to adjust the pH to 4.8-5.2, stirring and mixing at 45-55°C to obtain an aminosilane hydrolysate; (2) vacuum drying of silica, then adding it to a high-speed mixer, adding the vinylsilane hydrolysate and aminosilane hydrolysate in the form of a spray under nitrogen protection, stirring and mixing at 70-80°C to obtain silane-modified silica; (3) adding silane-modified silica and methylcyclohexane diisocyanate to acetone under nitrogen protection, stirring and reacting at 75-85°C, and obtaining modified silica after separation and purification.

8. The method for preparing packing straps using waste printing film according to claim 7, characterized in that: The volume ratio of vinyltriethoxysilane to aqueous ethanol solution is (0.4~0.8):10; the volume ratio of 3-aminopropyltriethoxysilane to aqueous ethanol solution is (0.4~0.8):10; the ratio of silica, vinylsilane hydrolysate, and aminosilane hydrolysate is 1g:(0.2~0.3)mL:(0.2~0.3)mL; the mass ratio of silane-modified silica to methylcyclohexane diisocyanate is (18~22):1.

Images