PET plastic steel packing belt and preparation method thereof

Abstract

The application relates to the technical field of packing belt materials, and discloses a PET plastic steel packing belt and a preparation method thereof, in particular to the following: a POSS composite type light stabilizer is synthesized; PET raw materials are prepared by processes of rubbing, polygranular molding, granulation, stirring and drying and melt purification and tackifying; the POSS composite type light stabilizer is used as a modified component of the PET raw materials, based on the pi-pi stacking effect between benzene rings, interface compatibility of the PET raw materials and the POSS composite type light stabilizer is realized, light aging resistant PET master batches are obtained by extruding and granulating through a double-screw extruder; and the PET plastic steel packing belt is prepared by processes of melt extrusion, multi-stage stretching and heat setting, the packing belt has excellent light aging resistance, can reach a high tensile breaking load level in the QB / T 4010-2010, and meets the green environmental protection trend.

Description

Technical Field

[0001] This invention relates to the field of strapping material technology, specifically to a PET plastic-steel strapping and its preparation method. Background Technology

[0002] PET strapping is a binding material made from polyethylene terephthalate (PET) through melt extrusion, multi-stage stretching, and heat setting. It combines the strength of steel strapping with the flexibility of plastic strapping and is widely used for packaging goods in logistics, building materials, timber, and chemical industries. With the advancement of green packaging and circular economy policies, using recycled PET raw materials to produce PET strapping has become the mainstream development direction in the industry. Among these, waste textiles rich in PET fibers, after resource recycling, are gradually becoming one of the high-quality sources of recycled PET raw materials.

[0003] However, conventional PET materials have poor resistance to light aging and cannot meet the requirements for outdoor use. The benzene ring structure contained in the PET molecular chain absorbs ultraviolet energy and triggers a photochemical reaction, which causes the chemically active ester groups to break (photo-oxidative degradation), thereby causing molecular chain breakage and resulting in aging phenomena such as yellowing and brittleness of the material.

[0004] Currently, commercially available outdoor PET packing straps are typically black packing straps modified with carbon black masterbatch for UV resistance. Carbon black has a strong absorption capacity for ultraviolet rays, effectively inhibiting their damage to the PET molecular chain. However, inorganic carbon black has poor compatibility with the organic PET matrix, easily introducing interface defects, which adversely affects the material's mechanical properties. Furthermore, carbon black has broad-spectrum light absorption characteristics, strongly absorbing visible and infrared light, which account for over 95% of the solar spectrum. Under direct sunlight, the surface temperature of black PET packing straps increases significantly (thermal accumulation effect), intensifying the thermal motion of PET molecular chain segments, resulting in a substantial decrease in the material's creep resistance. Therefore, black PET packing straps are prone to stress relaxation due to thermal expansion and high-temperature creep under outdoor exposure, ultimately leading to loosening and failure of the packing.

[0005] Studies have found that UV-absorbing light stabilizers (such as hydroxybenzophenones) primarily absorb ultraviolet light, and when used in combination with free radical-scavenging light stabilizers (such as hindered amines), they can significantly enhance the light aging resistance of materials. However, directly adding small-molecule light stabilizers to the polymer matrix has significant drawbacks: firstly, they are easily volatilized and lost during high-temperature processing, reducing the actual effective component content; secondly, during use, they are easily migrated from the matrix due to molecular diffusion or compatibility issues, and are lost with the medium under the influence of the external environment, resulting in poor light aging resistance of the material. Summary of the Invention

[0006] To address the common problems of easy volatility loss, strong molecular diffusion, and easy migration and loss of small molecule light stabilizers, this invention, based on molecular structure design, anchors benzotriazole UV light absorbing light stabilizers and hindered amine free radical capturing light stabilizers onto a POSS framework with nano-enhancing effect through chemical bonding, thus preparing a POSS composite light stabilizer.

[0007] By utilizing the π-π stacking effect between benzene rings, the independently developed POSS composite light stabilizer is added to PET raw materials made from waste textiles as a modifying component. The resulting PET plastic steel strapping not only has excellent resistance to light aging, but also meets the high tensile breaking load level in QB / T 4010-2010 "Polyester Strapping", and conforms to the trend of green environmental protection.

[0008] A method for preparing PET plastic strapping includes the following steps:

[0009] Step 1: Synthesize the POSS composite light stabilizer, including the following sub-steps:

[0010] (1) Disiloxane octaphenyl POSS and 3-bromopropene are mixed at a molar ratio of 1:(2.00-2.05) and subjected to hydrosilylation reaction at 60-80℃ under the action of platinum catalyst to obtain dibromooctaphenyl POSS;

[0011] (2) Dibromooctaphenyl POSS was mixed with 2,2,6,6-tetramethylpiperidineamine at a molar ratio of 1:(2.00-2.10) and subjected to a nucleophilic substitution reaction at 50-70°C in the presence of an acid-binding agent to obtain di(secondary amino hindered amino)octaphenyl POSS;

[0012] (3) Di(secondary amino hindered amino)octaphenyl POSS and 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole were mixed at a molar ratio of 1:(2.10-2.30) and carried out an addition reaction at 75-90℃ under the action of an organic base catalyst to obtain a POSS composite light stabilizer;

[0013] Step 2: Mix 3-8 parts by weight of the POSS composite light stabilizer with 100 parts by weight of PET raw material, and then extrude and granulate the mixture using a twin-screw extruder at 240-270°C to obtain a light-resistant PET masterbatch.

[0014] Step 3: The light-resistant PET masterbatch is melt-extruded into a strip preform at 240-270℃ using a twin-screw extruder. After water cooling and solidification, it is stretched 4-8 times at 100-140℃ and then heat-set at 80-120℃ to obtain PET plastic steel strapping.

[0015] Preferably, the platinum catalyst is a cassiterite catalyst containing 2-5% Pt.

[0016] Preferably, the acid-binding agent is triethylamine.

[0017] Preferably, the organic base catalyst is 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0018] Preferably, the process parameters of the twin-screw extruder in steps two and three are set as follows: the temperatures of zones 1-6 are 235-245℃, 245-255℃, 250-265℃, 260-275℃, 265-275℃, and 260-270℃, respectively.

[0019] Preferably, the PET raw material is obtained from waste textiles rich in PET fibers through a process of twisting, pelletizing, pelletizing, stirring and drying, and melt purification and thickening.

[0020] The PET plastic steel strapping prepared according to the above method has a width of 15.5-16.5 mm and a thickness of 0.75-0.85 mm.

[0021] Preferably, the tensile breaking load of the PET plastic steel strapping is ≥5.80kN.

[0022] Beneficial effects:

[0023] This invention uses disiloxane octaphenyl POSS as the molecular skeleton, first introducing a bromine functional group through a propenyl-hydrosilylation reaction with 3-bromopropene, then grafting 2,2,6,6-tetramethylpiperidineamine (hindered amine free radical scavenging light stabilizer) through a nucleophilic substitution reaction of primary amine-bromine, and finally grafting 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole (benzotriazole ultraviolet light absorbing light stabilizer) through a secondary amine-acryloyloxy addition reaction to obtain a POSS composite light stabilizer;

[0024] PET raw materials are produced by using waste textiles as the source of PET through processes such as kneading, granulation, pelletizing, stirring and drying, and melt purification and thickening.

[0025] Using POSS composite light stabilizer as a modifying component of PET raw material, the interfacial compatibility between PET raw material and POSS composite light stabilizer is achieved based on the π-π stacking effect between benzene rings. The raw material is then extruded and granulated using a twin-screw extruder to obtain a light-resistant PET masterbatch.

[0026] Using light-resistant PET masterbatch as raw material, PET plastic steel strapping is produced through melt extrusion, multi-stage stretching and heat setting processes. The strapping product has a tensile breaking load ≥5.80kN, and the tensile breaking load change rate after xenon lamp aging for 1500h is <10%, with no yellowing or brittleness, showing excellent mechanical strength and light aging resistance. Detailed Implementation

[0027] Example 1:

[0028] The preparation of a POSS composite light stabilizer includes the following steps:

[0029] Step 1: Based on the propenyl-hydrosilylation reaction mechanism, octaphenyldisiloxane (POSS) reacts with 3-bromopropene, and the molar ratio of octaphenyldisiloxane to 3-bromopropene is controlled at 1:2.01 to generate dibromooctaphenyldisiloxane (POSS), whose chemical structural formula is as follows:

[0030] ;

[0031] Step 2: Based on the nucleophilic substitution mechanism of primary amine-bromine, dibromooctaphenylPOSS reacts with 2,2,6,6-tetramethylpiperidineamine, and the molar ratio of dibromooctaphenylPOSS to 2,2,6,6-tetramethylpiperidineamine is controlled at 1:2.03 to generate di(secondary hindered amine)octaphenylPOSS, whose chemical structural formula is as follows:

[0032] ;

[0033] Step 3: Based on the addition reaction mechanism of secondary amino-acryloyloxy group, under the action of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) catalyst, a POSS composite light stabilizer is generated by reacting di(secondary amino hindered amino)octaphenyl POSS with 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, and controlling the molar ratio of di(secondary amino hindered amino)octaphenyl POSS to 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole to 1:2.2. The chemical structure of the stabilizer is as follows:

[0034] ;

[0035] The chemical structural formula of R is: ;

[0036] The specific experimental steps for preparing the POSS composite light stabilizer are as follows:

[0037] Under nitrogen protection, 5.8 g of disiloxane octaphenyl POSS and 50 mL of anhydrous tetrahydrofuran were added to a three-necked flask and stirred at room temperature until completely dissolved. Then, 0.9 mL of 3-bromopropene and 30 μL of caster catalyst (containing 3% Pt) were added to the three-necked flask in sequence. The mixture was heated to 70 °C and stirred under reflux for 5 h. After cooling to room temperature, 15 mg of triphenylphosphine was added and stirred for 30 min. The catalyst was removed by filtration, and the solvent was removed by rotary evaporation under reduced pressure. The filtrate was dried under vacuum at 50 °C for 2 h to obtain dibromooctaphenyl POSS.

[0038] Under nitrogen protection, 4.6 g of dibromooctaphenyl POSS and 50 mL of anhydrous tetrahydrofuran were added to a three-necked flask and stirred at room temperature until completely dissolved. Then, 10 mL of anhydrous tetrahydrofuran solution containing 1.1 g of 2,2,6,6-tetramethylpiperidinamine (CAS No. 36768-62-4) and 2 mL of triethylamine were added to the three-necked flask. The mixture was heated to 60 °C and stirred for 8 h. After cooling to room temperature, the solvent was removed by rotary evaporation under reduced pressure. The mixture was washed with deionized water and dried under vacuum at 50 °C for 2 h to obtain di(secondary amino hindered amino)octaphenyl POSS.

[0039] Under nitrogen protection, 3.9 g of di(secondary amine hindered amino)octaphenyl POSS, 20 mL of anhydrous toluene, and 20 mL of anhydrous acetonitrile were added to a three-necked flask and stirred at room temperature until completely dissolved. Then, 10 mL of anhydrous toluene solution containing 1.8 g of 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole (CAS No. 96478-09-0) and 0.08 g of DBU (approximately 10 mol%, based on the secondary amine reaction site) were added to the three-necked flask. The mixture was heated to 80 °C and stirred for 24 h. After cooling to room temperature, the solvent was removed by rotary evaporation under reduced pressure. The mixture was purified by silica gel column chromatography (ethyl acetate / petroleum ether = 1:3, v / v) and dried under vacuum at 50 °C for 2 h to obtain a POSS composite light stabilizer.

[0040] The 1H NMR spectrum characterization of the POSS composite light stabilizer is as follows: 1 H NMR (DMSO-d6, 400MHz) δ: 0.12 (s, 6H), 0.94-0.97 (t, 4H), 1.14-1.15 (d, 6H), 1.21 (s, 12H), 1.26 (s, 12H), 1.51-1.57 (m, 4H), 1.68-1.76 (m, 8H), 1 .87(s, 2H), 2.49-2.57(m, 6H), 2.71-2.77(m, 2H), 2.84-2.94(m, 8H), 4.18-4.20(t, 4H), 6.94-7.82(m, 54H), 9.17(s, 2H);

[0041] The molecular formula of POSS composite light stabilizer is C 110 H 130 O 20 N 10 Si 10 The elements were tested using a Vario EL III elemental analyzer. The experimental values ​​(theoretical values, %) were: C 60.31 (60.24), H 5.90 (5.97), N 6.35 (6.39).

[0042] Based on this, the error range between the actual and theoretical values ​​of C, H and N elements is within 0.3%. Combined with the proton spectrum results, it can be proven that the POSS composite light stabilizer was successfully synthesized.

[0043] The preparation method of disiloxane octaphenyl POSS is as follows: Under nitrogen protection, 21.3 g of phenyltrimethoxysilane, 2.9 g of sodium hydroxide, 100 mL of isopropanol, and 3 mL of deionized water are added to a three-necked flask. The mixture is stirred and mixed at room temperature for 30 min, then heated to 90 °C and refluxed for 5 h. After cooling to room temperature, the mixture is stirred and reacted for 15 h. The mixture is filtered, repeatedly washed with isopropanol, and dried under vacuum at 60 °C for 2 h to obtain the intermediate. Under nitrogen protection, 11.3 g of phenyltrimethoxysilane, 2.9 g of sodium hydroxide, 100 mL of isopropanol, and 3 mL of deionized water are added to a three-necked flask. The intermediate, 3.0 mL of triethylamine, and 100 mL of anhydrous tetrahydrofuran were added to a three-necked flask and stirred for 2 hours under ice bath conditions. Then, 10 mL of anhydrous tetrahydrofuran solution containing 3.4 g of methyldichlorosilane was slowly added dropwise to the flask. After the addition was complete, the ice bath was removed, and the mixture was stirred at room temperature for 24 hours. The filtrate was collected, and the solvent was removed by rotary evaporation under reduced pressure. The solution was repeatedly washed with methanol and dried under vacuum at 60 °C for 2 hours to obtain disiloxane octaphenyl POSS, whose chemical structure is as follows:

[0044] ;

[0045] The 1H NMR spectrum of disiloxane-octaphenyl POSS is characterized as follows: 1 H NMR (DMSO-d6, 400MHz) δ: 0.18-0.19 (d, 6H), 2.84-2.88 (m, 2H), 7.33-7.57 (m, 40H).

[0046] Example 2:

[0047] The preparation of PET plastic-steel strapping I includes the following steps:

[0048] Step one involves preparing PET chip raw materials from waste textiles. The preparation process is as follows:

[0049] (1) Kneading: The waste textile materials are sent to the shredder by forklift for primary kneading. After primary kneading, the materials are conveyed to the fine crusher by belt for secondary kneading. The kneaded materials are then conveyed to the screw feeder by blower.

[0050] (2) Granulation and pelletizing: The screw feeder transports the material to the granulation host. The material generates frictional heat and high pressure between the friction discs, causing the semi-finished product after cutting to clump together and form. The temperature is controlled at 195℃. The semi-finished product after cooling in the transfer chamber is blown into the cutting machine by the fan and cut into uniform particles.

[0051] (3) Stirring and drying: The material is conveyed to the vacuum drum by the feeder and the Roots blower. The temperature is controlled at 120°C by the heat transfer oil heating method, and the material moisture content is dried to less than 1000ppm.

[0052] (4) Melt purification and thickening: The dried material is blown by the Roots blower at the bottom of the drum to the hopper above the twin-screw extruder. The hopper is connected to the feed port of the twin-screw extruder. The screw speed is set to 200 r / min. The vacuum port is opened at the front end of the die head. The temperature of zones 1-6 is set to 240℃, 250℃, 260℃, 265℃, 270℃, and 265℃. The molten material formed by the twin-screw extruder is initially filtered through a coarse filter (filtration accuracy of 80 mesh) and continuously fed into the liquid phase thickening equipment. Under the action of high temperature (275℃) and vacuum (100Pa), it is mixed at a speed of 60 r / min for 30 min. Then it is pumped to the fine filter (filtration accuracy of 100 mesh) through the discharge pump. Finally, it is vacuum dried at 120℃ for 4 h through the slicing system to obtain PET slice raw material.

[0053] Step 2: Prepare photo-aging resistant PET masterbatch I. Its formula is: 100 parts by weight of PET chip raw material and 3 parts by weight of POSS composite light stabilizer. The preparation method is as follows: Based on the π-π stacking effect between benzene rings, interfacial compatibility between the PET chip raw material and the POSS composite light stabilizer is achieved. The mixture is then extruded and granulated using a twin-screw extruder to obtain photo-aging resistant PET masterbatch I. The preparation steps are as follows: 100 parts by weight of dried PET chip raw material and 3 parts by weight of POSS composite light stabilizer are added to a high-speed mixer and mixed at 1800 rpm for 5 minutes to obtain a premixed material. The premixed material is then added to a twin-screw extruder through the feed port. The screw speed is set to 200 rpm, and a vacuum port is opened at the front of the die head. The temperatures of zones 1-6 are set to 240℃, 250℃, 260℃, 265℃, 270℃, and 265℃, respectively. The extrudate is water-cooled, pelletized, and vacuum-dried at 120℃ for 4 hours to obtain photo-aging resistant PET masterbatch I.

[0054] Step 3: Prepare PET plastic-steel strap I. The preparation process is as follows:

[0055] (1) Melt extrusion: 100 parts by weight of light-resistant aging-resistant PET masterbatch I is blown by the Roots blower at the bottom of the drum to the hopper above the twin-screw extruder. The hopper is connected to the feed port of the twin-screw extruder. The screw speed is set to 200 r / min. The vacuum port is opened at the front end of the die head. The temperatures of zones 1-6 are set to 240℃, 250℃, 260℃, 265℃, 270℃, and 265℃. The molten material formed by the twin-screw extruder enters the gear pump of the plastic steel belt production line through the three-way valve outlet, and then passes through the die head (temperature is 260℃) to extrude a strip-shaped preform.

[0056] (2) Water cooling and solidification: The extruded strip-shaped preform enters the water cooling tank for solidification. The cooling water temperature is 65℃ and the distance between the die orifice and the water surface is 30mm.

[0057] (3) Multi-stage stretching: The cooled PET strip preform is pulled into the oven (temperature is 120℃) by the first traction machine, and then stretched by the second and third traction machines. The stretching temperature is 120℃ and the stretching ratio is 6 times. After stretching, embossing is performed.

[0058] (4) Heat setting: The PET strapping is set by a heat setting machine at a temperature of 100°C. It is then cooled down to 40°C by a cold setting water tank device and wound into shape to obtain PET plastic steel strapping I.

[0059] Example 3:

[0060] The only difference between PET plastic steel strapping II and PET plastic steel strapping I is that PET masterbatch II with light aging resistant properties is used instead of PET masterbatch I with light aging resistant properties.

[0061] The preparation steps of the light-resistant PET masterbatch II are the same as those of the light-resistant PET masterbatch I. The only difference is that the formula of the light-resistant PET masterbatch II is: 100 parts by weight of PET chip raw material and 5 parts by weight of POSS composite light stabilizer.

[0062] Example 4:

[0063] The only difference between PET plastic steel strapping III and PET plastic steel strapping I is that PET masterbatch III, which is resistant to light aging, is used instead of PET masterbatch I.

[0064] The preparation steps of the light-resistant PET masterbatch III are the same as those of the light-resistant PET masterbatch I. The only difference is that the formula of the light-resistant PET masterbatch III is: 100 parts by weight of PET chip raw material and 8 parts by weight of POSS composite light stabilizer.

[0065] Comparative Example 1:

[0066] The only difference between PET plastic steel strapping a and PET plastic steel strapping I is that PET chips are used instead of light-resistant PET masterbatch I.

[0067] Comparative Example 2:

[0068] The only difference between PET plastic steel strapping b and PET plastic steel strapping I is that physical blended PET masterbatch is used instead of light-resistant PET masterbatch I.

[0069] The formulation of the physically blended PET masterbatch is as follows: 100 parts by weight of PET chip raw material and 3 parts by weight of compound light stabilizer (composed of 1.5 parts by weight of 2,2,6,6-tetramethylpiperidinamine and 1.5 parts by weight of 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole). The preparation steps are as follows: 100 parts by weight of dried PET chip raw material and 3 parts by weight of compound light stabilizer are added to a high-speed mixer and mixed at 1800 rpm for 5 min to obtain a premixed material; the premixed material is added to a twin-screw extruder through the feed port, the screw speed is set to 200 r / min, the vacuum port is opened at the front of the die head, and the temperatures of zones 1-6 are set to 240℃, 250℃, 260℃, 265℃, 270℃, and 265℃, respectively. The extrudate is water-cooled, pelletized, and vacuum-dried at 120℃ for 4 h to obtain the physically blended PET masterbatch.

[0070] Performance testing:

[0071] (1) According to QB / T 4010-2010 "Polyester Strapping" standard, test the width, thickness and tensile breaking load of PET plastic steel strapping samples; when testing the tensile breaking load, the effective length of the sample is 100mm and the tensile speed is 100mm / min.

[0072] (2) Light aging resistance test: The test was conducted according to GB / T 16422.2-2022 "Laboratory Light Source Exposure Test Methods for Plastics - Part 2: Xenon Arc Lamp" standard, with the aging conditions being: irradiance of 0.51 W / (m²). 2 •nm) (340nm), black mark temperature 65℃, test chamber temperature 35℃, 102min light irradiation, 18min spraying, and after aging for 1500h, the appearance changes of the samples were recorded, and the tensile breaking load of the aged samples was tested according to QB / T 4010-2010 "Polyester Strapping" standard. The change rate of tensile breaking load of the samples after 1500h xenon lamp aging was calculated. The specific method is as follows:

[0073] Tensile breaking load change rate (%) = (initial tensile breaking load - tensile breaking load after xenon lamp aging for 1500h) / initial tensile breaking load × 100%;

[0074] The results of the above performance experiments are shown in Table 1.

[0075] Table 1. Performance test results of PET plastic steel strapping

[0076] Product Type Width (mm) Thickness (mm) Tensile breaking load (kN) Appearance changes Change rate (%) of tensile fracture load of the sample after xenon lamp aging for 1500 h PET plastic steel strapping I 16.0 0.80 5.80 No yellowing or cracking 9.3 PET Plastic Steel Straps II 16.1 0.80 6.05 No yellowing or cracking 7.1 PET Plastic Steel Straps III 15.9 0.81 6.18 No yellowing or cracking 5.6 Comparative Example 1 16.0 0.80 4.31 Yellowing and cracking occurred. / Comparative Example 2 16.1 0.81 4.27 Yellowing occurs, but no brittleness is observed. 38.5

[0077] A comprehensive analysis of the above experimental results leads to the following conclusions:

[0078] Conclusion 1: The PET plastic-steel strapping products prepared using the independently developed POSS composite light stabilizer of this invention have achieved significant improvements in mechanical strength and light aging resistance.

[0079] Among them, the tensile breaking load was increased by 34-43% compared with the unmodified PET plastic steel strapping a; the change rate of tensile breaking load of the sample after xenon lamp aging for 1500h was reduced by 75-85% compared with the PET plastic steel strapping b prepared using conventional compound light stabilizers).

[0080] Conclusion 2: The PET plastic steel strapping product prepared by the present invention has a tensile breaking load ≥ 5.80kN, which can reach the high tensile breaking load level in QB / T 4010-2010 "Polyester Strapping".

Claims

1. A method for preparing PET plastic-steel strapping, characterized in that, Includes the following steps: Step 1: Synthesize the POSS composite light stabilizer, including the following sub-steps: (1) Disiloxane octaphenyl POSS and 3-bromopropene are mixed at a molar ratio of 1:(2.00-2.05) and subjected to hydrosilylation reaction at 60-80℃ under the action of platinum catalyst to obtain dibromooctaphenyl POSS; (2) Dibromooctaphenyl POSS was mixed with 2,2,6,6-tetramethylpiperidineamine at a molar ratio of 1:(2.00-2.10) and subjected to a nucleophilic substitution reaction at 50-70°C in the presence of an acid-binding agent to obtain di(secondary amino hindered amino)octaphenyl POSS; (3) Di(secondary amino hindered amino)octaphenyl POSS and 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole were mixed at a molar ratio of 1:(2.10-2.30) and carried out an addition reaction at 75-90℃ under the action of an organic base catalyst to obtain a POSS composite light stabilizer; Step 2: Mix 3-8 parts by weight of the POSS composite light stabilizer with 100 parts by weight of PET raw material, and then extrude and granulate the mixture using a twin-screw extruder at 240-270°C to obtain a light-resistant PET masterbatch. Step 3: The light-resistant PET masterbatch is melt-extruded into a strip preform at 240-270℃ using a twin-screw extruder. After water cooling and solidification, it is stretched 4-8 times at 100-140℃ and then heat-set at 80-120℃ to obtain PET plastic steel strapping.

2. The method for preparing a PET plastic-steel strapping according to claim 1, characterized in that, The platinum catalyst is a cassiterite catalyst containing 2-5% Pt.

3. The method for preparing a PET plastic-steel strapping according to claim 1, characterized in that, The acid-binding agent is triethylamine.

4. The method for preparing a PET plastic-steel strap according to claim 1, characterized in that, The organic base catalyst is 1,8-diazabicyclo[5.4.0]undec-7-ene.

5. The method for preparing a PET plastic-steel strapping according to claim 1, characterized in that, The process parameters of the twin-screw extruder in steps two and three are set as follows: the temperatures of zones 1-6 are 235-245℃, 245-255℃, 250-265℃, 260-275℃, 265-275℃, and 260-270℃, respectively.

6. The method for preparing a PET plastic-steel strapping according to claim 1, characterized in that, The PET raw material is obtained from waste textiles rich in PET fibers through a process of kneading, granulation, pelletizing, stirring and drying, and melt purification and thickening.

7. A PET plastic-steel strapping prepared according to any one of claims 1-6, characterized in that, The PET plastic steel strapping has a width of 15.5-16.5mm and a thickness of 0.75-0.85mm.

8. A PET plastic-steel strapping according to claim 7, characterized in that, The tensile breaking load of the PET plastic steel strapping is ≥5.80kN.